Access the full text.
Sign up today, get DeepDyve free for 14 days.
(2015)
Koval’chuk, PIK Reactor Complex, Vol. 4: Concept of the Investment Project “Development of the Instrumental Base of the PIK Reactor Complex
E. Iashina, E. Velichko, M. Filatov, W. Bouwman, C. Duif, A. Brûlet, S. Grigoriev (2017)
Additive scaling law for structural organization of chromatin in chicken erythrocyte nuclei.Physical review. E, 96 1-1
C. Hardacre, J. Holbrey, C. Mullan, T. Youngs, D. Bowron (2010)
Small angle neutron scattering from 1-alkyl-3-methylimidazolium hexafluorophosphate ionic liquids ([C(n)mim][PF(6)], n=4, 6, and 8).The Journal of chemical physics, 133 7
B. Dorner (1981)
Coherent Inelastic Neutron Scattering in Lattice Dynamics
Leonardo Chiappisi, S. Prévost, I. Grillo, M. Gradzielski (2014)
Chitosan/alkylethoxy carboxylates: a surprising variety of structures.Langmuir : the ACS journal of surfaces and colloids, 30 7
A. Okorokov (2011)
Investigation of triple spin correlations and spin dynamics in ferromagnetsCrystallography Reports, 56
R. Hempelmann (2000)
Quasielastic Neutron Scattering and Solid State Diffusion
F. Mezei, C. Pappas, T. Gutberlet (1985)
Neutron Spin Echo SpectroscopyEurophysics News, 16
G. Cheng, P. Varanasi, Chenlin Li, Hanbin Liu, Y. Melnichenko, B. Simmons, M. Kent, Seema Singh (2011)
Transition of cellulose crystalline structure and surface morphology of biomass as a function of ionic liquid pretreatment and its relation to enzymatic hydrolysis.Biomacromolecules, 12 4
F. Mezei (1980)
Neutron Spin Echo, 128
D. Lebedev, M. Filatov, A. Kuklin, A. Islamov, E. Kentzinger, R. Pantina, B. Toperverg, V. Isaev-Ivanov (2005)
Fractal nature of chromatin organization in interphase chicken erythrocyte nuclei: DNA structure exhibits biphasic fractal propertiesFEBS Letters, 579
W. Xie, Jian He, H. Kang, Xinfeng Tang, Song Zhu, M. Laver, Shanyu Wang, J. Copley, C. Brown, Qingjie Zhang, T. Tritt (2010)
Identifying the specific nanostructures responsible for the high thermoelectric performance of (Bi,Sb)2Te3 nanocomposites.Nano letters, 10 9
A. Bianchi, M. Kenzelmann, L. Debeer-Schmitt, Jon White, E. Forgan, J. Mésot, M. Zolliker, J. Kohlbrecher, R. Movshovich, E. Bauer, J. Sarrao, Z. Fisk, C. Petrovic, M. Eskildsen (2008)
Superconducting Vortices in CeCoIn5: Toward the Pauli-Limiting FieldScience, 319
F. Mezei (1972)
Neutron spin echo: A new concept in polarized thermal neutron techniquesZeitschrift für Physik A Hadrons and nuclei, 255
Mitra Yoonessi, J. Gaier (2010)
Highly conductive multifunctional graphene polycarbonate nanocomposites.ACS nano, 4 12
F. Hippert, E. Geissler, J. Hodeau, E. Lelièvre-Berna, J. Regnard (2006)
Neutron and X-ray spectroscopy
A . I . Okorokov , Crystallogr
K. Kakurai (1998)
Neutron Spin Echo Spectroscopy, 53
P. Anderson (1997)
Concepts In Solids: Lectures On The Theory Of Solids
Poverkhn . : Rentgenovskie , Sinkhrotronnye Neitr . Issled . , No . 11 , 3 ( 2008 ) . 42 . N . K . Pleshanov , Nucl . Instrum
Christiane Franz, T. Schröder (2015)
RESEDA: Resonance spin echo spectrometerJournal of large-scale research facilities JLSRF, 1
D. Pines (1963)
Elementary excitations in solids : lectures on phonons, electrons and plasmons
S. Grigoriev, S. Maleyev, A. Okorokov, Y. Chetverikov, R. Georgii, P. Böni, D. Lamago, H. Eckerlebe, K. Pranzas (2005)
Critical fluctuations in MnSi nearTC: A polarized neutron scattering studyPhysical Review B, 72
D. Pushcharovsky (2021)
Mineralogical Crystallography: Look in the Past, New Trends, and HighlightsCrystallography Reports, 66
(2015)
Diffractometers on the PIK Reactor for Solving Fundamental and Applied Problems (Izd-vo PIYaF, Gatchina, 2015) [in Russian
Y. Henry, S. Mangin, T. Hauet, F. Montaigne (2006)
Positive exchange-bias induced by interface domain wall quenching in GdFe/TbFe filmsPhysical Review B, 73
F. Mezei, C. Pappas, T. Gutberlet (2002)
Neutron Spin Echo Spectroscopy: Basics, Trends and Applications, 601
V. Raghuwanshi, R. Harizanova, S. Haas, D. Tatchev, I. Gugov, C. Dewhurst, C. Rüssel, A. Hoell (2014)
Magnetic nanocrystals embedded in silicate glasses studied by polarized SANSJournal of Non-crystalline Solids, 385
Dian Chen, A. Nakahara, Dongguang Wei, D. Nordlund, T. Russell (2011)
P3HT/PCBM bulk heterojunction organic photovoltaics: correlating efficiency and morphology.Nano letters, 11 2
A. Well (1992)
Double-disk chopper for neutron time-of-flight experimentsPhysica B-condensed Matter
R. Rinaldi, L. Liang, H. Schober (2009)
Neutron Applications in Earth, Energy, and Environmental Sciences
G. Gröger, W. Meyer-Zaika, C. Böttcher, F. Gröhn, Christian Ruthard, C. Schmuck (2011)
Switchable supramolecular polymers from the self-assembly of a small monomer with two orthogonal binding interactions.Journal of the American Chemical Society, 133 23
(2015)
Development of the Instrumental Base of the PIK Reactor Complex" (Izd-vo FGBU PIYaF NITs "Kurchatovskii Institut
S. Mühlbauer, B. Binz, F. Jonietz, C. Pfleiderer, A. Rosch, A. Neubauer, R. Georgii, P. Böni (2009)
Skyrmion Lattice in a Chiral MagnetScience, 323
C. Sanson, O. Diou, Julie Thévenot, E. Ibarboure, A. Soum, A. Brûlet, S. Miraux, E. Thiaudière, Sisareuth Tan, A. Brisson, V. Dupuis, Olivier Sandre, S. Lecommandoux (2011)
Doxorubicin loaded magnetic polymersomes: theranostic nanocarriers for MR imaging and magneto-chemotherapy.ACS nano, 5 2
N. Pleshanov (2017)
Neutron bandpass limiting chopperNuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 872
A. Furrer, J. Mésot, T. Strässle (2009)
Neutron Scattering in Condensed Matter Physics
(2008)
Rentgenovskie, Sinkhrotronnye Neitr
ISSN 1063-7745, Crystallography Reports, 2021, Vol. 66, No. 2, pp. 195–215. © The Author(s), 2021. This article is an open access publication, corrected publication, 2021. Russian Text © The Author(s), 2021, published in Kristallografiya, 2021, Vol. 66, No. 2, pp. 191–213. REVIEWS a b, b b M. V. Kovalchuk , V. V. Voronin *, S. V. Grigoriev , and A. P. Serebrov National Research Centre “Kurchatov Institute,” Moscow, 123182 Russia Konstantinov Petersburg Nuclear Physics Institute of National Research Centre “Kurchatov Institute,” Gatchina, Leningradskaya oblast, 188300 Russia *e-mail: Voronin_VV@pnpi.nrcki.ru Received June 5, 2020; revised June 5, 2020; accepted June 13, 2020 Abstract—The program of developing the instrument base of reactor complex PIK is reviewed. This program is carried out in correspondence with the Decree of the President of the Russian Federation No. 356 on July 25, 2019 and the Federal Scientific and Technical Program for the Development of Synchrotron and Neutron Research and Research Infrastructure on the 2019–2027s. The general concept and plans of forma- tion of the instrument base are reported in the four-volume manuscript PIK Reactor Complex (editors V.L. Aksenov and M.V. Kovalchuk), published in 2015. DOI: 10.1134/S1063774521020061 CONTENTS The potential of neutron methods for analyzing differ- ent objects is demonstrated in Fig. 1. Introduction In the second half of the XX century, a particular 1. Instrumental Program in Condensed-Matter attention was paid to the creation of neutron research Physics and Biophysics centers in the Soviet Union. A number of remarkable 1.1. Neutron Diffraction Complex scientists were involved in the development of neutron scattering technique. The experience of using neutron 1.2. Spectrometry Complex scattering technique was consolidated and inherited by 1.3. Complex of Small-Angle Diffractometers scientific schools of the Russian Federation. In the 1.4. Ref lectometry Complex XXI century, the fields where neutrons are used cover, as well as previously, most of up-to-date problems of 2. Program of Studies in Physics of Elementary fundamental physics and the questions concerning Particles and Nuclear Physics technical applications of neutrons; however, the 2.1. High-Intensity Superfluid-Helium UCN mainstream of neutron studies is gradually transferred Source Based on the PIK Reactor to biological sciences, physics and chemistry of nano- 2.2. Promising Experiments in Physics of Parti- structured and so-called soft materials (polymers, col- cles on the PIK Reactor loids, etc.) and the analysis of materials and methods of target drug delivery. 2.3. Promising Experiments in Nuclear Physics on the PIK Reactor The National Research Centre “Kurchatov Insti- tute” (NRC KI) in Moscow is the most advanced research centre in Russia, where modern large physi- INTRODUCTION cal research systems (primarily, synchrotron radiation and neutron sources) are used in life sciences. An Neutrons as a tool for studying matter and laws of interdisciplinary world-level center (Center of Con- nature are known to have a number of significant verging Nano-, Bio-, Information, and Cognitive Sci- advantages over other analytical tools. These advan- ences (NBICS Center)) has been organized at the tages are as follows: f irst, a wide range of distances and NRC KI in the last years. The Department of Molec- times; second, ideal functioning as a probe for study- ular and Radiation Biology at the Konstantinov ing magnetism; third, high sensitivity and selectivity Petersburg Nuclear Physics Institute of the NRC KI with respect to chemical elements and isotopes; and (Gatchina) has been successfully functioning since fourth, deep penetration into material studied. In the 1960s. addition, the neutron is a very convenient object for studying fundamental interactions, because it is A neutron source can be used most eff iciently when involved in all interaction types that are known to date high-efficiency neutron beams extracted from a high- (strong, weak, electromagnetic, and gravitational). f lux reactor are supplied without loss to ultramodern 195 196 KOVALCHUK et al. 1. INSTRUMENTAL PROGRAM 10 Engine X-ray radiography, tomography IN CONDENSED-MATTER PHYSICS AND BIOPHYSICS 2 X-ray diffraction analysis 10 Texture 1.1. Neutron Diffraction Complex of texture Reflectometry Exact knowledge of the atomic structure of materi- 4 Cell and small-angle als, being a basis for correct understanding of their scattering properties, allows one to change deliberately these 6 Domains properties. Traditionally, the fields of study of con- densed matter in which the use of neutron diffraction Polymers 8 is most eff icient are considered to be as follows: struc- Magnetic X-ray diffraction tural analysis of compounds consisting of light and structures analysis heavy atoms (hydrides, oxides), compounds with ele- 10 10 Nuclear physics ments having close numbers (alloys, intermetallic Charge density and physics compounds), and biological compounds with applica- of particles tion of isotopic contrasting (basically replacement of 14 Nucleus hydrogen with deuterium) of their individual frag- ments, as well as analysis of the magnetic structure of 15 Nucleon crystals (i.e., determination of the magnitude and Length, m direction of atomic magnetic moments (MMs)). In all aforementioned cases, X-rays fail to distinguish details that are necessary for solving structure. An important Fig. 1. Comparison of objects studied by different neutron scattering methods and their scales. factor is the low (in comparison with X-rays) neutron absorption in a medium. As a consequence, the neu- tron penetration depth in a material may be fairly large experimental setups, which make it possible to per- (up to several centimeters), due to which one can form most advanced studies in all the aforementioned obtain more adequate structural information and fields. Therefore, both components (the high neutron study the microstructure of bulk materials and engi- source efficiency and modern level of instrument neering products. base) are of equal importance for successful imple- The range of application of neutron diffraction, as mentation of scientific programs of the International well as the experimental possibilities of this method, Center of Neutron Research based on the PIK (Rus- have dramatically expanded for the last time. The con- sian abbreviation for the “vessel beam research”) reac- ventional lines of research (physics, chemistry, mate- tor. Thus, one of the main principles of the general rials science) were supplemented with molecular biol- concept of the design of experimental stations— ogy, pharmacology, geology, and engineering sci- upgrade of the instrument base—should be performed ences. The general technical progress and new hand-in-hand with the improvement of the source. concepts in the diffractometer design, formation of The work on equipping the PIK reactor complex neutron beams, and development of detector systems with modern systems and devices is performed within have provided possibilities in neutron-diffraction two projects: “Reconstruction of the Laboratory studies that seemed to be impossible only 15–20 years Complex for the PIK Research Reactor Complex” ago. Currently, one can determine ab initio the crystal (completion period 2017–2020) and “Formation of structure, refine the complex structure of both con- the Instrument Base for the PIK Reactor Complex” ventional materials and nanomaterials, analyze local (completion period 2019–2024). These projects structural distortions with an error of ∼0.1 Å, investi- should result in a research complex equipped with gate transient process with characteristic times at a 25 neutron stations, two cold-neutron sources, a hot- level of 10 s, and operate with samples having a volume neutron source, and an ultracold-neutron (UCN) of ∼1 mm . source (Figs. 2, 3), due to which the requests for neu- tron studies both from the side of the scientific and A unique range of application of neutron diffrac- technological complex of Russia and from the side of tion is the study of the magnetic structure of crystals at many European partners will be satisfied for a long the atomic level, i.e., the spatial distribution of MM time. Ten neutron-guide systems (Fig. 2) make it pos- density (in the simplest case, determination of the sible to transport neutrons to 17 experimental setups, magnitude and direction of atomic MMs). The mag- which are located in the neutron-guide hall under netic scattering of neutrons is determined by the mag- low-background conditions. In total, it is planned to nitude of effective MM (the sum of orbital and spin provide up to 50 positions on beams in three experi- moments of shell electrons), i.e., depends on the scat- mental halls of the complex, on which different tering angle. Using polarized neutrons, one can mea- research groups can perform experiments simultane- sure very small (several hundredths of Bohr magne- ously. ton) atomic MMs. CRYSTALLOGRAPHY REPORTS Vol. 66 No. 2 2021 Neutrino SESANS Membrana-2 INSTRUMENT BASE OF THE REACTOR PIK 197 D1 IN1 IN-2 IN-3 IRINA Test spectrometer Hot neutron source Test reflectometer SEM ТНР D3 DEDM Tenzor DC1 UCN source Polarized-neutron UCN splitter diffractometer ТЕХ-3 Cryostat Helium vacuum pump system UCN magnetic trap NERO-2 IN-4 Neutron Sonata Harmony β-decay IN1 Fig. 2. Schematic arrangement of experimental setups in the hall of horizontal channels and neutron-guide hall. Among the most important achievements obtained Diffractometer D1 is located on the thermal neu- tron beam emerging from the horizontal experimental using neutron diffraction, we should note the direct proof of the existence of different types of magnetic channel GEK-6' (Fig. 4). The principle of operation of D1 implies the use of the widest range of neutron ordering; the proof of the fundamental importance of radiation spectrum, implementation of variable wave- hydrogen bonds in polymers and organic macromole- length, maximal focusing and concentration of neu- cules; the determination of fine details of high-tem- tron beam on samples of different sizes, provision of perature superconductor structure; the detection of maximally possible resolution at a sufficiently high different types of magnetic, charge, and orbital order- aperture ratio, and high data collection rate due to the ing in complex oxides of transition metals; and many use of a complex wide-aperture and high-efficiency others. Examples of studies performed with the use of detector system. powder and single-crystal neutron diffraction can be found in [1, 2]. The parameters of diffractometer D1 are as follows: monochromator exit angle (2θ ) not smaller than High-resolution powder neutron diffractometer D1 is 125°; neutron wavelength after monochromator λ = intended for structural studies using elastic neutron 1.2–2.5 Å; working scan step 2θ is 0.05°; diffracto- scattering at a constant wavelength with subsequent full-profile analysis of measured neutron diffraction patterns. On the one hand, diffractometer D1, being most conventional with regard to solved problems, is intended for studying (using soft monochromatic neu- tron radiation) crystalline (organic, inorganic, and complex) compounds, magnetic structures, and the INAA temperature evolution of crystal and magnetic struc- tures of objects with a unit-cell parameter of several or PROGRAS several tens of angstrom, i.e., the overwhelming FISCO majority of inorganic materials (including nano- and multilayer materials). At the same time, due to the high resolution and high intensity of neutron f lux, one can use diffractometer D1 to solve such fundamental problems of crystallography as аb initio structure solu- tion using powders [3, 4]. D1 is convenient for Rietveld analysis of relatively large structures, such as zeolites with adsorbed mole- cules, fullerenes, and fullerene-like compounds, as well as for solving structures of some new “quasicrys- talline” materials. Fig. 3. Hall of inclined channels. CRYSTALLOGRAPHY REPORTS Vol. 66 No. 2 2021 5.0 m 198 KOVALCHUK et al. Beam cross-section on the sample 2 135 is 15 60 mm 112.5 3 m 1.5 m 4.5 m Beam cross-section Beam cross-section at the output of channel 6' on the monochromator 2 2 60 200 mm is 15 200 mm Fig. 4. Schematics of high-resolution powder diffractometer D1 on the channel GEK-6': (1) neutron guide, (2) monochromator, (3) optical collimator, (4) sample table, (5) detector collimation system, and (6) detector. –3 ple, Reuter-Stokes 975 × 8.4 mm) are proposed as meter resolution Δd/d < 3 × 10 (can be improved detectors. several times during exploitation); angular scan range 2θ= 4°–168°; maximum momentum transfer Q = Four-circle thermal-neutron diffractometer DC1 is max –1 12.5 Å ; available interplanar spacing range d = 0.5– intended for studying the atomic and magnetic struc- 15 Å; and neutron beam cross section in the sample ture [3, 4]. Diffraction from a single crystal makes it possible to observe finer structural reactions that are plane is (10 × 10)–(10 × 50) mm . inaccessible for the diffraction from a powder or poly- High-intensity powder diffractometer of D3. Ther- crystal. For example, very weak Bragg ref lections or mal-neutron powder diffractometer D3, which is weak diffuse scattering can be measured. Diffractom- characterized by a high f lux at the sample position, is eter DC1 is located on the thermal neutron beam out- intended for studying the atomic and magnetic struc- going from the horizontal experimental channel ture of various compounds [3, 4]. The experiments GEK-9 (Fig. 5). that call for high intensity can be separated into two The parameters of diffractometer DC1 are as fol- groups. The first includes experiments requiring a lows: working wavelengths 0.9, 1.2, and 2.4 Å (Cu, Si, high measurement rate: investigations with a high and PG focusing monochromators); monochromati- temporal resolution, i.e., with a short measurement zation Δλ/λ ≤ 3%; angular range of detection around time. In particular, these are studies in situ and in the vertical axis 2θ from –20° to 120°; angular range of operando, in which the data collection rate is an detection around the vertical horizontal axis 2θ from important factor for detecting rapidly disappearing –12.5° to 25° (or vice versa, from –25° to 12.5°, precursors or reaction mediators. Fast data collection depending on the design of detector lift device); pro- is necessary for studying phase transitions (PTs) or posed sample size no more than 10 × 10 mm; ranges of observing the structure evolution with a change in sample rotation angles: ω from –34° to 48°, χ from temperature, pressure, and magnetic and/or electric –80° to 200°, and Φ from –179° to 179°, the operating fields. The second group includes experiments where range depends on the sizes of χ ring, sample table, and the sample amount is very small (sometimes no more cryorefrigerator; the error in setting the system to a than 10 mg). Other examples of experiments for which specified angle no worse than 0.001°. high intensity is important are structural studies of Four-circle thermal-neutron diffractometer for tex- hydrogen-containing samples, weak effects in the fun- ture analysis TeX-3. TeX-3 is a four-circle thermal- damental physics of magnets and functional materials, neutron diffractometer, optimized for studying the and many others. texture (orientational distribution of crystallites) in The main parameters of diffractometer D3 are as polycrystalline materials. The anisotropy of polycrys- follows: monochromator crystal angles are 44.22° and talline materials affects significantly their behavior 90°; neutron wavelengths (for neutrons incident on a under different thermomechanical treatments, which sample) λ = 2.52, 1.54, 1.36, and 1.28 Å; working scan is highly important for optimizing such processes. step is 0.05°; interplanar spacing resolution Δd/d ∼ 2 × Note that crystallites have a preferred orientation in –3 10 ; angular scan range 2θ = 4°–132°; and neutron more than 90% of all crystalline materials. Thus, an beam cross section in the sample plane is 8 × 30 mm . analysis of crystal texture gives very rich information Linear position-sensitive helium counters (for exam- for many various investigations: from establishing the CRYSTALLOGRAPHY REPORTS Vol. 66 No. 2 2021 INSTRUMENT BASE OF THE REACTOR PIK 199 Neutron beam from GEK Monitor Sample Gate and 2 axes and axes PG Trap Cu Collimator 2D detector (256 256 mm ) Monochromator Filter (Cu or PG) or another Sample monochromator (Si) instead of this assembly Monochromatic neutron beam 2D detector Fig. 5. Schematic arrangement of diffractometer DC1 on GEK 9. relationship between the structure and properties of applying neutron diffraction. Note also that the angu- latest functional materials to understanding the occur- lar resolution of texture neutron diffractometers gen- rence of geological processes in rocks. The materials erally exceeds that of X-ray diffractometers with pole- under study vary from pure metals and their alloys, figure goniometers, due to which deconvolution of intermetallic compounds, and composites to minerals. complex diffraction spectra with closely spaced peaks (as, for example, in multiphase systems or low-sym- Different approaches are used to determine tex- metry materials) can be performed. The diffractome- ture. Currently, diffraction techniques are applied ter TeX-3 is placed on the thermal neutron beam most widely to measure the parameters of preferred emerging from the horizontal experimental channel crystallographic orientation. X-ray diffraction with a GEK-6. pole-figure goniometer is a generally accepted stan- The parameters of diffractometer ТeХ-3 are as fol- dard for such measurements. Nevertheless, neutron lows: diffractometer working wavelength is 1.24 Å; diffraction has some significant advantages, especially monochromatization Δλ/λ ≤ 3%; ranges of sample in the case of bulk samples. For most of materials, the rotation angles: ϕ from –360° to 360°; χ from –360° to attenuation of incident neutron beam due to absorp- 360°; ω from –46° to 46°; suggested samples: cube tion and scattering is an order of magnitude lower than with an edge up to 10 mm, sphere with a diameter up in the case of X-rays. Therefore, the neutron penetra- to 20 mm, cylinder with a diameter up to 15 mm and a tion depth is on the order of centimeters instead of sev- height up to 15 mm; position-sensitive detector with eral millimeters for X-rays. A necessary condition for area of 200 × 200 mm. unambiguous interpretation of intensity variations in X-ray techniques (in both Bragg and Laue geometries) Polarized-neutron diffractometer DIPOL is pro- is to retain the narrow incident beam within the region posed for a wide range of magnetic studies, such as under study during sample rotation. In contrast, when determination of magnetic structures and specif ic fea- using neutrons, it is preferred to place a bulk (1–10 cm tures of magnetic ordering in crystalline objects, anal- in diameter) sample in a wide beam, due to which the ysis of magnetic phase diagrams, detailed study of same volume can be investigated at any stage. Since complex magnetic structures and magnetic domains, the diffracted signal is averaged over volume rather investigation of magnetization density distribution, than over surface in this case, the grain statistics is sig- specific features of magnetic form factor, and local nificantly improved in comparison with conventional susceptibility. To implement these possibilities, the X-ray studies. Thus, neutron diffraction has diffractometer scheme provides operation in two dif- undoubted advantages for determining complete pole ferent modes: classical polarized-neutron diffraction figures in coarse-grained aggregates. and XYZ-polarization analysis. The X-ray scattering intensity depends strongly on In a classical experiment, a polarized-neutron f lux the Bragg angle, whereas in the case of neutrons this falls on a sample, and the polarization of scattered dependence is practically absent. Therefore, the peaks neutrons is not analyzed. The sample is magnetized by obtained at large angles can be estimated more exactly a magnetic field applied along the vertical axis Z, the CRYSTALLOGRAPHY REPORTS Vol. 66 No. 2 2021 200 KOVALCHUK et al. 1.2. Spectrometry Complex 10 8 Inelastic neutron scattering (INS), a technique also referred to as neutron spectroscopy, is one of the cornerstones for any neutron research center based on a high-f lux neutron source. Dynamic properties play a very important role in condensed-matter physics, chemistry, biophysics, biology, and materials science; hence, the development of the INS method should to GEK-8 be one of the priority works carried out on the PIK 9 7 6 5 4 reactor. Proceeding from the critical situation with neutron spectroscopy in the Russian Federation, all researchers interested in the revival of this technique in our country may lay their hopes specifically on PIK [3]. Fig. 6. Schematic arrangement of the main units and func- INS is used to study the dynamic properties of tional components of diffractometer DIPOL: (1) mono- materials [5–8]. The importance of neutron spectros- chromator unit, (2) monochromator protection, (3) mon- copy for condensed-matter physics can be compared itor counter, (4) polarizer, (5) flipper, (6) diaphragm, (7) sample unit. Half-polarization mode: (8) position- with such a highly informative method as neutron dif- sensitive detector. Polarization-analysis mode: (9)guide- fraction. Neutron spectroscopy and diffraction are field coil on sample, (10) polarization analyzer, complementary techniques, they cannot be counter- (11)detector unit. posed. Diffraction (both nuclear and magnetic neu- tron scattering) makes it possible to determine the crystal and magnetic structures of materials, i.e., to intensities of scattered neutrons are measured for two answer the question where atoms are located (or how possible polarization states, and then their ratio R (the their MMs are oriented). Using diffraction, one can so-called flip ratio) is calculated. This mode is also also reveal PTs in materials. However, diffraction referred to as “half-polarized experiment.” It demon- methods generally do not make it possible to under- strates a giant increase in sensitivity to weak magnetic stand the mechanisms of the phenomena occurring in signals and is used mainly to study the spin density dis- condensed matter, the nature of PTs, and the factors tribution and specific features of the form factor of causing formation of a particular ground state of the magnetic ions in the unit cell. system. INS may help to answer these deeper ques- tions, because this method yields spectra of elemen- In the XYZ-polarization method, the polarization tary excitations, both lattice excitations (phonons), is oriented along the X, Y, and Z axes, and the spin i.e., answers the question how atoms move, and elec- state of scattered neutrons is analyzed along the same tron and magnetic excitations (magnons, excitons, etc.). directions. This method is extremely efficient for sep- The concept of quasiparticles [9–13]—elementary arating the nuclear and magnetic contributions to excitations of different nature—is the most fruitful neutron scattering and highly demanded when study- concept in the condensed matter physics of the ing systems with interacting order parameters. Polar- XX century and one of the main tools of scientif ic cog- ization analysis also makes it possible to investigate the nition in this field of fundamental science. It is not a spin chirality in complex magnetic systems. mere chance that, when awarding the Nobel prize for the development of the technique of neutron studies of The diffractometer equipment for the sample unit condensed matter, one half of the prize was awarded is as follows: cryorefrigerator operating in the tem- for the development of neutron diffraction and the perature range Т = 10–340 K with a vacuum post; second for the development of INS. Indeed, exact cryostat (Т = 1.5–340 K); temperature controller knowledge of the total energy and symmetry of a sys- LakeShore 340; superconducting magnet with a verti- tem of bound atoms (crystal) and the difference cal field (up to 7 T); a system for 3D analysis of dif- between the energies of different crystalline phases fracted neutron beam; and a 2D position-sensitive does not make it possible to say anything about the detector. The diffractometer DIPOL is located on the physical properties of crystal: specific heat, magneti- hot-neutron beam emerging from the horizontal zation, susceptibility, thermal expansion, thermal experimental channel GEK-8 (Fig. 6). conductivity, and resistance. At the same time, ele- mentary-excitation spectra (dispersion relations and The parameters of polarized-neutron diffractome- density of excitation states) allow one to calculate cor- ter are as follows: operating wavelengths 0.7 and 1.0 Å; rectly all main physical properties and determine the polarized-neutron f lux on the sample (λ = 0.7 Å) ∼ PT mechanism [8, 14]. In other words, the diffraction 7 2 1× 10 n/(cm s); polarization 95% or more; mea- in condensed matter physics is to a great extent a surement temperature range 1.5–300 K; and resolu- method of diagnostics and searching for effects, while –1 tion in momentum transfer is 0.01 Å . spectroscopy is a method for determining the essence CRYSTALLOGRAPHY REPORTS Vol. 66 No. 2 2021 INSTRUMENT BASE OF THE REACTOR PIK 201 of phenomena and their driving forces and explaining play a decisive role in determining the mechanism of the physical properties of materials. These two tech- HTSC. Currently, the magnetic and lattice excitations niques, being reasonably combined, supplement each in new-generation superconductors based on iron are other quite well. A signif icant deviation in favor of one being studied. of them reduces the scientific efficiency of a neutron The role played by INS in the study of systems with source. strong electron correlations can hardly be overesti- mated. Measurements of magnetic excitation spectra The excitations available to INS reflect many made it possible to reveal the nature of unusual ground degrees of freedom of systems studied. Examples of states and reveal excitations characteristic of Kondo quasiparticles are phonons, magnons (spin waves in systems, heavy fermion modes, and intermediate terms of the classical theory of magnetism), spin den- valence. Numerous anomalies of lattice dynamics sity waves, paramagnons, spinons, excitons, rotons, were found. Low-dimensional systems, including phasons, etc. [15]. Neutron spectroscopy is a tool for those with quasi-one-dimensional spin chains and studying excitations (vibrational and rotational) in quasi-two-dimensional planes of quantum spins, have molecules. There are many types of one-site (single- been investigated by the INS method. Some funda- ion) excitations: local oscillation modes of impurity mental results were obtained, and magnetic exci- atoms in crystals, transitions between levels of ground tations of new nature were found. multiplets split in the crystal electric field, intermulti- plet transitions. INS is applied to study the critical Backscattering spectrometers and spin-echo dynamics and physics of PTs. Neutron spectroscopy devices turned out to be irreplaceable for studying the plays an important role in studies of diffusion and dynamic processes at low energy transfers, which –3 relaxation phenomena in both solids and soft materials called for extremely high energy resolution (10 and (polymers, biological objects, organic and inorganic –5 10 meV, respectively) [17, 18]. Low-energy dynamics compounds). Fluids (including quantum ones), emul- is characteristic of relaxation processes and physical sions, suspensions, amorphous materials and other phenomena characterized by long characteristic times disordered media, quasicrystals—all these objects are and low frequencies. The class of objects requiring for characterized by peculiar forms of excitations, which studies of low-energy dynamics is very wide. Both manifest themselves in neutron spectra. structural phenomena and phenomena occurring in INS is very important for studying the lattice magnetic and electronic subsystems are investigated. dynamics [16]. Direct measurements of the dispersion Triple-axis thermal-neutron spectrometer IN1. Tri- relations and density of phonon states (including par- ple-axis spectroscopy makes it possible to tune a spec- tial ones) made it possible to study the ion–ion inter- trometer to measurements at any point of the energy– action potentials, understand the nature of formation momentum or reciprocal space. Due to this feature, of many materials, and explain the anomalies of their triple-axis spectrometers are considered to be one of physical properties. In particular, an excellent quanti- the main tools for comprehensive studies of the inelas- tative description for superconductors with the pho- tic processes in solids and enter the set of experimental non mechanism of superconductivity was obtained setups necessary for a high-f lux neutron source. Spec- based on INS spectra. trometric measurements involve the following pro- Neutron spectrometers turned out to be irreplace- cesses: diffraction of the primary neutron beam from a monochromator (formation of a monochromatic neu- able for studying PTs (both structural and magnetic) tron beam, rotation axis 1), scattering of the mono- and revealing the modes to which the structural or chromatic neutron beam from the sample (rotation magnetic instability of system is related [16]. The crit- axis 2), and diffraction of the neutron beam from the ical dynamics in the PT physics is another important niche for INS. Neutron spectroscopy plays a key role analyzer (rotation axis 3). To increase the eff iciency of neutron scattering in the spectrometer, the Rowland in the study of magnets of different classes: ferro- and focusing geometry is applied, in which the source, ferrimagnets, antiferromagnets, zone magnets and monochromator, and sample are located on one cir- systems with spin density waves, spin glasses, molecu- cumference. The proposed scheme is in correspon- lar magnets, and metalorganic magnets. Neutron spectra contain information about effective exchange dence with the modern concepts of designing triple- axis spectrometers. Neutron studies on the spectrom- constants and other important parameters of magnetic eter IN1 will be performed with a variable wavelength systems [17]. at neutron scattering in the horizontal plane. The INS is considered to be one of the most promising spectrometer is proposed to be installed in the main and highly informative methods for solving the prob- hall of the PIK reactor (channel GEK-10, see Fig. 7). lem of high-temperature superconductivity (HTSC) The parameters of spectrometer IN1 are as follows: and studying superconductors of different types (in neutron energy range E = 15–100 meV, wavelength particular, cuprates). Although the HTSC problem i range λ = 0.9–2.36 Å; monochromatization Δλ/λ ≤ has not yet been solved, a very large amount of infor- mation on both the lattice subsystem and magnetic 3%; energy resolution ΔE ≤ 3 meV (FWHM); sug- excitations has been accumulated to date, which may gested sample size no more than 30 × 30 mm. CRYSTALLOGRAPHY REPORTS Vol. 66 No. 2 2021 202 KOVALCHUK et al. 16 11 10 9 6 7 4 3 2 1 tron-guide hall of the PIK reactor (neutron-guide sys- tem of channel GEK-2, neutron guide NG-1; see GEK-10 Fig. 9). The parameters of spectrometer IN3 are as follows: range of neutron energies 15–100 meV, wavelength range 0.9–2.36 Å; monochromatization Δλ/λ ≤ 3%; energy resolution ΔE ≤ 3 meV (FWHM); suggested sample size no more than 30 × 30 mm; neutron polar- ization P ≥ 95%. 15 8 5 Time-of-flight neutron spectrometer IN4 is intended for measuring spectra of inelastic neutron scattering in Fig. 7. Schematic arrangement of the main units and func- different materials, both in solids (crystals and disor- tional components of spectrometer IN1: (1) input slit dered media) and in liquids, polymers, and other sys- (VS), (2) shutter, (3) filter, (4) monitor 1, (5) monochro- tems of soft-material type in the interests of physics, mator unit, (6, 13) collimator, (7) monitor 2, (8) mask, chemistry, biology, and materials science [3]. A mod- (9, 12) diaphragm, (10) sample unit, (11) trap, (14)monitor 3, (15) analyzer unit, (16) detector unit. Pro- ern time-of-f light (TOF) spectrometer is an efficient tection elements are colored gray. scanner of excitations, due to which collective and local excitation modes can be studied in a wide range of energy and momentum transfers. The energy reso- Triple-axis cold-neutron spectrometer IN2 is lution and resolution in the momentum space can be intended for high-resolution studies of low-energy varied by choosing the energy of neutrons incident on collective excitations in solids [3]. This spectrometer is the sample and the spectrometer operation mode. The expected to provide high resolution in momentum most f lexible scheme, which allows one to study both and/or energy transfers and be eff icient in solving elas- magnetic and structural (lattice) excitations is the tic scattering problems, where an important factor is a direct-geometry spectrometer. The volume of the large signal/noise ratio. Neutron studies on the spec- region available for scanning in the Q–E space for a trometer IN2 will be performed with a variable wave- TOF spectrometer with direct geometry exceeds that length at neutron scattering in the horizontal plane. To for the inverse-geometry spectrometer (Fig. 10). In use efficiently neutron scattering in the spectrometer, particular, the range of momentum transfers for the Rowland focusing geometry is also applied. The spec- first-type spectrometers is much wider. trometer is proposed to be mounted in the neutron- To solve various problems of condensed-matter guide hall of the PIK reactor (neutron-guide system of physics, chemistry, biology, and materials science, channel GEK-2, see Fig. 8). one must use different measurement modes: both the mode with a high energy resolution (∼2%) and the The parameters of spectrometer IN2 are as follows: mode with a moderate resolution (∼4%) but high energy range 2.3–36 meV; wavelengths 1.5–6.0 Å; intensity. The spectrometer IN4 is a f lexible system, monochromatization: Δλ/λ ≤ 3%; energy resolution which provides a particular operation mode necessary ΔE ≤ 25, 80, 120 μeV (FWHM) for incident neutron for user. energies of 2.3, 4, and 5 meV, respectively; and pro- posed sample sizes (10 × 10)–(30 × 30) mm. The parameters of IN4 spectrometer are as follows: the range of neutron energy transfers is 0.5–20 meV; Polarized-thermal-neutron triple-axis spectrometer the relative energy resolution in the position of elastic IN3. Along with the energy analysis in the main oper- peak not worse than 5%; and the sample size no more ating mode of spectrometer, the spin states of the neu- than 30 × 30 mm. trons scattered from the sample are also analyzed. The Neutron spin-echo (NSE) setup SEM. The spin- operation of the spectrometer in this mode should echo spectroscopy setup SEM is intended for studying provide efficient solution of problems for complex sit- the dynamics of supra-atomic, molecular, and supra- uations with magnetic and lattice excitations having molecular structures: synthetic and biological poly- close energies or momenta. Neutron studies on the mers, macromolecules, and fullerenes. Methods of spectrometer IN3 will be performed with a variable spin-echo spectrometry are applied to investigate slow wavelength at neutron scattering in the horizontal relaxation processes. These processes are observed plane [3]. Rowland focusing geometry is also applied when studying “soft matter” and glass formation: for in the spectrometer in order to use efficiently neutron example, thermal vibrations of membrane surface in a scattering. To implement the possibility of polariza- microemulsion; dynamics of polymer chains in a melt; tion analysis, the spectrometer is equipped with a and the motion of thermally activated domains in pro- polarizer (installed before the monochromator), two teins, which is an important key for understanding f lippers (installed before sample and after it), a system protein functions. of guiding fields on the sample, and an analyzer of the polarization of neutrons scattered by the sample. The NSE spectrometry has the highest energy resolu- spectrometer is proposed to be mounted in the neu- tion that can be attained for neutron spectrometers. CRYSTALLOGRAPHY REPORTS Vol. 66 No. 2 2021 INSTRUMENT BASE OF THE REACTOR PIK 203 GEK-2 12 3 12 13 15 45 6 14 16 17 Fig. 8. Schematic arrangement of the main units and functional components of spectrometer IN2: (1) neutron-guide insert/polarizer, (2) elliptical neutron guide, (3) velocity selector, (4) input slit (VS), (5) shutter, (6) monitor 1, (7) monochroma- tor unit, (8, 15, 18) collimator, (9) monitor 2, (10) mask, (11, 14) diaphragm, (12) sample unit, (13) trap, (16) monitor 3, (17) analyzer unit, (19) detector unit. Protection elements are colored gray. GEK-2 NG-1 78 9 11 13 14 12 15 16 Fig. 9. Schematic arrangement of the main units and functional components of spectrometer IN3: (1) insert, (2) elliptical neutron guide, (3) input slit (VS), (4) shutter, (5) monitor 1, (6) monochromator unit, (7) collimator, (8) monitor 2, (9) mask, (10) guide- field coil on monochromator, (11, 17) diaphragm, (12) f lipper 1, (13) sample unit, (14) trap, (15) guide-field coil on sample, (16)f lipper 2, (18) monitor 3, (19) analyzer unit, (20) detector unit. Protection elements are colored gray. This method is applied mainly in experiments on covers the dynamic scale from microscopic times of quasi-elastic scattering to study the relaxation pro- atomic collisions and spin exchange to macroscopic cesses located on the energy scale near zero energy times of slow relaxation processes involving large mol- transfer. In contrast to other methods based on inelas- ecules and atomic conglomerates. Unlike other exper- tic neutron scattering, the NSE technique implies imental methods providing dynamic information, measurement of the intermediate scattering function such as muon spin spectroscopy, NMR, Mossbauer S(Q, t) at the reciprocal space point Q in dependence spectroscopy, or measurements of magnetometric sus- of the relaxation time t of the process under study. The ceptibility, NSE yields simultaneously access to micro- –12 –7 range of measured relaxation times, from 10 to 10 s, scopic information through the value of momentum CRYSTALLOGRAPHY REPORTS Vol. 66 No. 2 2021 204 KOVALCHUK et al. L L ferent portions of neutron-guide channels with subse- PM MS quent interpolation of experimental data in order to determine the neutron f lux at the designed power. Sample The spectrometer parameters are as follows: mea- surement range 0.5–20 Å; instrumental resolution 5%; characteristic statistics collection time 1 h (depends on PC FOM SD the beam intensity and reactor power); mobile system, which can be installed in any beam. Chopper cascade Detector 1.3. Complex of Small-Angle Diffractometers Fig. 10. Block diagram of direct-geometry spectrometer Small-angle neutron scattering (SANS) is one of IN4. L , L , and L are, respectively, the distances PM MS SD the most informative methods for studying the struc- between the choppers P and M, chopper М and sample S, and sample S and detector D. The C and FO choppers are ture of material on the supra-atomic scale: from sev- auxiliary; they absorb neutrons with energy unfit for the eral nanometers to several tens of micrometers. There- experiment (multiply transmitted by the main choppers). fore, SANS investigations cover an extremely wide class of objects: from the structure of proteins and viruses in biology, medicine, and pharmacology to transfer Q in reciprocal space. Thus, NSE can be con- polymer nanocomposite materials, emulsions, and sidered as a link between the aforementioned integral microemulsions in chemistry, from incommensurate methods and microscopic methods (i.e., conventional magnetic structures and critical f luctuations at phase techniques of triaxial and TOF neutron spectrometry). transformations in the condensed matter physics to The operation of spin-echo spectroscopy setup the fractal structures of granular materials in materials SEM is based on the principle of modulation of neu- science and metallurgy and minerals in geology [21–34]. tron spectrum over phase wavelengths of Larmor pre- Small-angle neutron scattering set-up Membrana-2. cession of neutron spin in a magnetic field [19]. Two The small-angle diffractometer Membrana-2 is different principles of spin echo are implemented in intended for studying supra-atomic, molecular, and this instrument: the resonance spin-echo and the supramolecular structures of different objects: syn- Mieze principle (or principle of sinusoidal modulation thetic and biological polymers, macromolecules, and of neutron flux intensity incident on the sample). fullerenes [3]. A peculiar class of objects of study Using the neutron spin precession in a magnetic field includes nanoparticles: nanotubes; catalysts; and to measure the dynamic scattering function of objects nanophase inclusions in metals, alloys, and compos- studied, S(Q, t) ∼ S(Q, ω)cos(ωt)dω, the spectrome- ites. Agglomerates of nanoparticles are formed in peri- ter makes it possible to separate the processes of odic structures, fractals, and systems with short-range changes in the momentum and spin state of neutron in order; they all require studies in a wide spatial range. the scattering processes in objects with participation of Therefore, the small-angle diffractometer Membrana-2 nuclear and magnetic subsystems. The Mieze option is designed as an SANS system with a maximally wide [20] allows one not to restrict oneself to the study of range of momentum transfers in one-shot measure- objects with a spin dependence of scattering cross sec- ment. Neutron studies on the small-angle diffractom- tion (magnets, superconductors, hydrogen-contain- eter Membrana-2 will be performed in the monochro- ing media) but analyze additionally quasi-elastic pro- matic mode with a possibility of changing wavelength cesses occurring in practically any systems and under and in the polychromatic mode with application of the any conditions, including the processes in an external TOF technique (Fig. 11). magnetic field. The parameters of the system are as follows: range The spectrometer parameters are as follows: neu- of neutron wavelengths in use is 4.5–20 Å; monochro- tron wavelength range 4.0–12 Å; monochromatization matization Δλ/λ ≤ 10% (a possibility of monochroma- Δλ/λ ≤ 20%; range of momentum transfers q is 0.01– tization Δλ/λ ≤ 2–26% with a pair of choppers in –1 1.5 Å ; beam polarization on the sample P = 0.95; 0 dependence of the chopper type and sample–detector suggested sample size no more than 20 × 20 mm; distance is considered additionally); range of momen- –1 range of measured times 0.01–10 ns (at λ = 12 Å) and tum transfers q = 0.001–0.5 Å ; beam divergence is 0.001–2 ns (at λ = 4.0 Å). i varied in dependence of the number of collimating sections and the diaphragm size (from 10 × 10 to 30 × Test neutron spectrometer TNR is intended for mea- 30 mm); the sample size is 15 × 15 mm. surements of real neutron spectrum on the channel GEK-3. Despite the auxiliary character of the spec- Small-angle polarized-neutron scattering set-up Ten- trometer, it is demanded for tracking the construction zor. Small-angle polarized-neutron diffractometer of the neutron-guide system and the entire instrument Tenzor is designed for studying nuclear and magnetic base in the nearest years. The TNR spectrometer is inhomogeneities on the scale of 1–100 nm when car- used to measure the spectra of neutron beams in dif- rying out investigations in the fields of materials sci- CRYSTALLOGRAPHY REPORTS Vol. 66 No. 2 2021 INSTRUMENT BASE OF THE REACTOR PIK 205 Filter Diaphragm Choppers Selector Monitor Neutron guides Monitor Attenuator Neutron guide Polarizer Flipper Sample Diaphragms Neutron guides Fig. 11. Block diagram of small-angle neutron diffractometer Membrana-2. ence (defects, porosity), physics of metals (released tion Δλ/λ ≤ 10%; range of momentum transfers is –1 phases, clusters), technology of nanostructures and 0.001–0.5 Å ; beam divergence is varied in depen- nanomaterials (mesoporous systems, membranes, dence of the number of collimating sections in use and photonic crystals), physics of complex magnetic diaphragm size; sample size is 15 × 15 mm; and polar- structures, spin correlations at critical phenomena in izer polarizing efficiency P ≥ 0.95. ferromagnets, physics and chemistry of colloidal par- Small-angle polarized-neutron scattering set-up ticles (microemulsions, colloidal solutions, liquid SANS2. Functionally, the small-angle polarized-neu- crystals), and physics of superconductors [3]. The use tron diffractometer SANS2 is a highly specialized ana- of polarized neutrons expands the range of studies and log of the Tenzor system. This instrument is focused makes it possible, along with conventional selection of on studying the physics of complex magnetic struc- magnetic scattering, to study in SANS experiments the tures, spin correlations at critical phenomena in ferro- dynamics of spin correlations at small momentum magnets, spin waves, and physics of superconductors. transfers, many-body spin correlations, chiral proper- ties of materials, and magneto-nuclear interference. The parameters of the system are as follows: neu- Examples of SANS studies performed with polarized tron wavelength range is 5.0–12 Å; monochromatiza- and unpolarized neutrons can be found in [35, 36]. tion Δλ/λ ≤ 10%; range of momentum transfers is –1 0.001–0.1 Å ; beam divergence is varied in depen- The small-angle diffractometer Tenzor can be used dence of the number of collimating sections and the to carry out measurements using both unpolarized and diaphragm size (from 10 × 10 to 30 × 30 mm); sample polarized neutrons and analyze the polarization of the size is 15 × 15 mm; and polarizer efficiency P ≥ 0.95. beam transmitted through the sample. Neutron stud- P ies on the small-angle polarized-neutron diffractome- Spin-echo small-angle neutron scattering set-up ter Tenzor will be performed both in the standard SESANS. The SESANS system (Fig. 12) is intended monochromatic mode (Δλ/λ = 10%) with a variable for studying large-scale objects of biology, colloidal neutron wavelength and in the highly monochromatic and supramolecular chemistry, porous and membrane mode with the parameters Δλ/λ on the order of few systems, and domain structure of magnetic materials percent. [19, 37]. The spatial scale of the structures available for The diffractometer parameters are as follows: neu- study on this device covers three orders of magnitude: tron wavelength range is 4.5–20 Å; monochromatiza- from 100 nm to 40 μm. The technique of spin-echo CRYSTALLOGRAPHY REPORTS Vol. 66 No. 2 2021 206 KOVALCHUK et al. Detector Analyzer Guide-field coils Disk chopper Polarizer Table with sample Field stepper Electromagnets Slit with flippers Polarization rotators Fig. 12. Schematics of the SESANS system. small-angle neutron scattering (SESANS) is used to layer magnetometry based on deep profiles of scatter- investigate large-scale structural organization of chro- ing length densities. Currently, the range of applica- matin in the living cell nucleus [38]. To extract the tion of the neutron ref lectometry potential related to SESANS signal from samples of biological nature, nonspecular scattering and grazing-incidence SANS which are characterized by weak scattering power, one is constantly widening. must use a wide neutron wavelength range: from 0.1 to High-intensity polarized-neutron reflectometer 1 nm [39]. SONATA is intended for studying thin and atomically The principle of operation of this device is based on thin films; layered and laterally ordered structures; one of the versions of spin-echo method. SESANS magnetism in these structures; and fast-kinetics pro- differs from classical spin-echo systems by the fact that cesses occurring on boundaries, including the bound- precession regions have a form of a parallelogram. aries between solid and liquid phases. A schematic dia- Due to this, after a change in the motion direction as a gram of this device is shown in Fig. 13. The use of result of neutron scattering from the sample, the path polarized neutrons increases signif icantly its potential, length in the second arm of the system changes signif i- because this feature makes possible to study the mag- cantly, and the scattering angle turned out to be related netism of surfaces, as well as layered and laterally to the measured change in polarization. ordered structures. Along with the classical scheme of polarized-neutron reflectometry, it is planned to The parameters of the system are as follows: wave- implement the scheme with vector analysis of polar- length range is 3.5–12 Å; degree of monochromaticity ization [40]. Thus, there will be a possibility to obtain (in the monochromatic mode) Δλ/λ = 2%; range of more detailed and reliable information about the mag- measured scales is 0.1–40 μm; polarizing eff iciency of netic state of nanolayers, as well as to develop elements polarizer and analyzer P ≥ 0.95; neutron beam cross of innovation neutron spin (spin-manipulation) optics section on the sample is 10 × 10 mm ; horizontal scat- [41]. tering plane; and vertical divergence of neutron beam The interaction of incident neutrons with the sam- is 3′ or less. ple surface leads to their scattering in three main chan- nels (Fig. 14): specular ref lection (the angle of inci- 1.4. Reflectometry Complex dence is equal to the reflection angle), nonspecular scattering (in the mirror-ref lection plane), and graz- In the last decade neutron reflectometry has ing-incidence SANS (GISANS). become an eff icient method for studying surfaces, thin Specular ref lectometry is used to reconstruct the films, and multilayer structures. The increase in the deep profile of scattering length density, which gives f lux of neutron ref lectometers due to their installment information about the chemical (and isotopic) com- on more intense neutron sources and application of position of ref lecting layers on scales on the order of modern neutron optics made it possible to reduce sig- 1–100 nm. Polarized-neutron reflectometry can be nificantly the measurement time and increase spatial used in layer-by-layer vector magnetometry. Struc- resolution. The comparative simplicity of the analysis tural and magnetic inhomogeneities on the scales of of data on specular neutron reflection facilitates its 2 4 wide use for structure reconstruction and layer-by- 10 –10 nm (variations in scattering length density) in CRYSTALLOGRAPHY REPORTS Vol. 66 No. 2 2021 INSTRUMENT BASE OF THE REACTOR PIK 207 12 3 4 5 6 7 8 10 11 12 13 14 Fig. 13. Block diagram of neutron ref lectometer SONATA: (1) output window of transport neutron guide, (2, 6, 10) 2D dia- phragm, (3) first pair of chopper disks, (4) transmission flipper, (5) second pair of chopper disks, (7) beam combiner, (8, 12)f lipper, (9) monitor, (11) sample unit, (13) fan-shaped analyzer, (14) 2D PSD. The elements located after the output window of transport neutron guide are as follows: three collimation slits, elements of triple-disk chopper of original design [9], transmis- sion filter, beam combiner, two f lippers, monitor, sample unit, fan-shaped analyzer, and 2D position-sensitive detector (PSD). the mirror-ref lection plane can be resolved using slit The ref lectometer scheme will include innovation collimation in measurements with small grazing elements developed at the PNPI: a beam chopper [42, angles. Having collimated the incident beam in the 43] and a compact transmission supermirror polarizer horizontal and vertical planes, one can perform [44, 45]. The use of the proposed chopper will make it GISANS measurements on lateral inhomogeneities possible to reduce several times the sample measure- (variations in scattering length density) in the plane ment time in standard reflectometry experiments in oriented perpendicular to the mirror-ref lection plane. comparison with the double-disk chopper that is Thus, structural and magnetic inhomogeneities on the widely applied in neutron centers [46]. scales of 1–100 nm can be resolved. Polarized-neutron reflectometer NERO is a highly The parameters of ref lectometer SONATA are as specialized analog of the reflectometer SONATA, follows. Time-of-f light measurements: working spec- which operates in the specular ref lection mode. It is trum is 2–25 Å, variable range of λ and resolution intended mainly to study thin magnetic f ilms and mul- Δλ/λ; measurements at a constant wavelength: working tilayer structures. wavelengths are 2–25 Å, optimal wavelength is 5.2 Å, resolution Δλ/λ ∼ 3–10%, maximum momentum –1 transfers are no less than 1 Å (specular scattering), –1 –1 Grazing-incidence 0.05 Å (nonspecular scattering), and 0.2 Å PSD small-angle scattering (GISANS); degree of beam polarization exceeds 98%. Nonspecular scattering Vertical scattering plane reflectometer HARMONY. Neutron reflectometer HARMONY is a time-of- f light device with a vertical scattering plane. The main lines of research for this ref lectometer are as follows: air–liquid, liquid–solid, and solid–air interfaces; dynamic systems; diffuse (nonspecular) scattering; and thin magnetic films. The following device opera- tion modes are implemented to solve the aforemen- tioned problems: unpolarized-neutron reflectometry Sample in the specular and nonspecular scattering modes and polarized-neutron ref lectometry in the specular mir- ror and nonspecular scattering modes with polariza- tion analysis. Investigations can be performed on the ref lectometer in both measurement modes at ref lec- tion from the sample surface both from above and from below. The characteristic resolved sizes over the sample depth are 10–1000 Å. The ref lectometer parameters are as follows: work- ing wavelength range 2–20 Å; range of momentum Fig. 14. Channels of neutron scattering neutrons from the transfers to the sample surface (the perpendicular sample surface under conditions of point geometry: spec- –1 ular reflection, nonspecular scattering in the specular- component) is Q ∼ 0.005–0.5 Å ; degree of neutron reflection plane xz; grazing-incidence small-angle neu- beam polarization in the polarization mode up to P ∼ tron scattering (GISANS). For simplicity, GISANS is 96%; neutron beam cross section in the sample plane shown in only one plane; actually, it f ills in the entire PSD is (0.1 × 10)–(4.0 × 100) mm . window. CRYSTALLOGRAPHY REPORTS Vol. 66 No. 2 2021 Specular reflection 208 KOVALCHUK et al. increased in order to increase the accuracy; in addi- Vacuum module tion, new concepts, techniques, and nonstandard UCN guide equipment are also called for. Superfluid helium chamber Deuterium premoderator 2.1. High-Intensity Superfluid-Helium UCN Source Graphite Based on the PIK Reactor moderator Under development is a source of ultracold neu- Lead screen trons (UCNs) with a density 10–100 times higher than the UCN density on existing world sources (Figs. 15, 16; Table 1). This increase in the UCN intensity will be achieved due to the application of new technology with superf luid helium. A program of studying funda- mental interactions on the UCN source, including the Support carriage search for neutron electric dipole moment and precise measurement of its lifetime, is planned. Both prob- lems are of key importance for the physics of elemen- Fig. 15. Design of the UCN source on the PIK RC. tary particles and cosmology. Researchers from the NRC KI and JINR and their foreign colleagues will work on UCN beams. Currently, these studies are car- The reflectometer has the following parameters: ried out on the reactor at the Institute Laue–Langevin neutron wavelength 4.5 Å; wavelength resolution (ILL) (Grenoble, France). However, the first studies Δλ/λ = 0.02 and 0.05 in the high- and medium-reso- in the f ield of UCN physics were performed in Russia, lution modes, respectively; range of scattered-neutron and it is important to restore Russian priorities in this detection angles 2θ = 0°–10°; degree of neutron beam field. polarization P > 96%; and minimum size 10 × 10 mm. Test neutron reflectometer TNR is intended for test- 2.2. Promising Experiments in Physics of Particles ing polarizing and unpolarizing neutron mirrors when on the PIK Reactor designing neutron guides and other neutron optical devices for the PIK reactor complex (RC). The auxil- Magnetic resonance UCN spectrometer for measuring iary character of the spectrometer is compensated by the neutron EDM. The experiment on searching for the the fact that it is called for tracking the construction of neutron electric dipole moment (EDM) is related to the neutron-guide system, in particular, for estimating the general problem of the theory of elementary parti- cles: adequate description of the processes occurring the quality of internal neutron-ref lecting coating. The ref lectometer provides four measurement modes; the with violation of spontaneous CP- and T-symmetry. choice of a particular mode is determined by the phys- The EDM arises in modern theoretical models in the ical problem to solve: mode I for a “white” unpolar- first order of weak interaction and turns out to be at –26 –28 ized beam, mode II for a “white” polarized beam, the level of 10 –10 e cm. mode III for a monochromatic unpolarized beam, and The most precise (to date) limitation on the neu- mode IV for a monochromatic polarized beam. –26 tron EDM value (less than 2 × 10 e cm) was The ref lectometer parameters are as follows: oper- obtained at the ILL, where one chamber for storing ating wavelengths (time-of-flight measurements) UCNs and a mercury comagnitometer for monitoring range from 0.9 to 5 Å; monochromatization is Δλ/λ ∼ magnetic conditions were used. Systematic errors may 1%; beam polarization P > 99%; and available range of occur in this scheme in the presence of magnetic field –1 momentum transfers Q ∼ 0.003–0.3 Å . gradient. A differential magnetic resonance spectrom- eter with two UCN storage chambers, system for dou- ble analysis of polarization, and four detectors with a 2. PROGRAM OF STUDIES IN PHYSICS common constant magnetic field (Fig. 17) provide a OF ELEMENTARY PARTICLES radically different possibility for monitoring system- AND NUCLEAR PHYSICS atic effects. A test experiment was performed on the –26 ILL reactor, where a limit less than 5 × 10 e cm was Modern physics of elementary particles is a close obtained. The development of a new UCN source on interweaving of cosmology and properties of Universe the PIK reactor with a density two orders of magni- in the early stage of its formation, structure of elemen- tude higher than that at the ILL will provide an EDM tary particles and their interactions, nuclear physics, –27 and physics of phase transformations. One of the ways measurement accuracy at a level better than 10 e cm. to obtain new data in this field is to increase the mea- The discovery of neutron EDM or new limitation on surement accuracy in low-energy physics, in particu- its magnitude at this level may become a decisive fac- lar, in neutron physics. To this end, one needs high- tor in the choice of a theory adequately describing the intensity neutron sources, because statistics must be phenomenon of violation of CP symmetry. CRYSTALLOGRAPHY REPORTS Vol. 66 No. 2 2021 INSTRUMENT BASE OF THE REACTOR PIK 209 EDM n-n' GRAVITRAP NEUTRINO Neutron decay UCN source Magnetic trap Compressor room Operator room Fig. 16. Planned arrangement of the UCN source with superf luid helium and experimental setup on the GEK-4 channel of PIK RC. “Neutron EDM determination by crystal-diffraction the experiments on measuring the neutron lifetime by method” (DEDM) system. When designing an experi- storing UCNs in a magnetic trap fabricated with the mental platform with a large aperture and intensity on aid of permanent magnets is presented in Fig. 19. a cold-neutron beam in the neutron-guide hall, the Magnetic holding of neutrons makes it possible to top priority problem is to organize a crystal-diffraction exclude collisions of neutrons with walls. In a mag- experiment aimed at searching for the neutron EDM netic trap, UCNs of certain polarization are ref lected on the DEDM system. This tool will be a universal by magnetic barrier and do not collide with walls. The platform for studying the characteristics of neutron goal of this experiment is to reach statistical sensitivity and fundamental interactions (Fig. 18). The main in measurements of the neutron lifetime at a level of concept is the use of giant electric fields of noncen- 0.3 s. trosymmetric crystal. The magnitudes of fields on the “Neutron β-decay” system. The main goal of this entire neutron path through a crystal are in the range experiment is to measure the electron asymmetry of 8 9 4 of 10 –10 V/cm, which is 10 times higher than the neutron β-decay with a relative precision of (1–2) × fields attainable in laboratory by conventional meth- –3 10 . The experimental setup (Fig. 20) is based on a ods. When searching for the neutron EDM, an accu- superconducting solenoid with a magnetic field –27 racy of (2–3) × 10 e cm can be achieved using new- strength of 0.35 T in the region of uniform field and class crystals (BSO, BGO). 0.80 T in the region of magnetic plug at a current of 1000 A. The correlation coefficient in the neutron β- Large gravitational trap (GT) for measuring the neu- decay is measured due to the magnetic collimation of tron lifetime. The increase in the accuracy of neutron the electron escape angle and averaging over neutrino lifetime measurements will make it possible to verify the theoretical models of nucleosynthesis in the early Universe and the validity of the Standard Model of Table 1. Parameters of UCN source elementary particles. The system (Fig. 19) is based on Parameter Value the principle of gravitational gate for holding UCNs in a material trap. The UCN density in the new trap is –1 6 Total output, s 7.8 × 10 higher than that in the previous one by a factor of Energy release in helium chamber, W 2 about 30. The neutron-lifetime measurement accu- 3 3 racy in this system is expected to be 0.2 s. UCN f lux density, n/cm 1.3 × 10 Volume of UCN source chamber, L 40 System for measuring the neutron lifetime using mag- Working temperature of UCN converter, K 1.2 netic trapping (MT) of UCNs. A schematic diagram of CRYSTALLOGRAPHY REPORTS Vol. 66 No. 2 2021 210 KOVALCHUK et al. (а) (b) Upper Direct Four magnetometers Magnetic UCN trap UCN (top) Lateral field coils detectors Valves UCN detectors Magnetic screens Analyzers UCN Flipper Polarizer Grounded RF coils Lower ± High-voltage Four magnetometers electrodes UCN trap electrodes (bottom) Fig. 17. (a) Schematic diagram of the EDM system and (b) PNPI EDM spectrometer on the ILL reactor (test experiment). 3 7 10 11 12 13 15 2 45 6 8 9 14 Fig. 18. Schematic diagram of the DEDM system: (1) neutron beam, (2) double-crystal monochromator, (3, 15) beam trap, (4) neutron guide, (5) polarizer, (6) spin f lipper, (7) 3D polarization analysis system, (8) working crystal unit, (9) nonmagnetic system of sample positioning, (10) single-crystal monochromator, (11) nonabsorbing supermirror analyzer, (12) spin-orienting coil, (13) crystal ref lector, and (14) 2D PSD. escape angles. Magnetic collimation is performed by a formed for many years. Numerous experiments on magnetic plug, and averaging over neutrino escape accelerators, reactors, and artificial neutrino sources angles is performed by collecting all protons from the were aimed at solving this problem. Sterile neutrino is neutron β-decay using a distributed electric potential. a candidate for dark-matter particles. The hypothesis The formation of polarization neutron beam and its of oscillations into sterile state can be verif ied by direct analysis are proposed to perform using a supermirror measurement of the dependence of neutrino f lux and multislit polarizer. The TOF technique with a beam neutrino energy spectrum at different distances in the chopper and rate selector is used. This approach will range of 6–12 m. The PIK reactor opens unique pos- make it possible to fix the neutron decay point. The sibilities for these studies due to the compact core and application of crossed electric and magnetic fields high power of the reactor. The detection of reactor makes it possible to separate protons and electrons. antineutrinos is based on the reaction of inverse β-decay Knowing the neutron decay point and using the TOF and use of a liquid scintillator with gadolinium. Pho- technique for protons, one can measure the longitudi- tomultipliers record two successive events: instanta- nal proton momentum. Due to this, one can pass to neous f lare from a positron and annihilation of 511-keV neutrino-asymmetry measurements. A neutron beam γ quanta, after which the delayed signal from γ quanta arrives at the decay region, limited by a cylindrical of the (nGd, γ) reaction with generated neutron is electrode. All protons are extracted from the neutron recorded. The energy spectrum of antineutrino is decay region by electric field and arrive at the proton reconstructed from the energy spectrum of positrons. detector. Electrons move to the electron detector. Detector will be located in the main hall under the “Neutrino” setup. Experimental search for possible transport corridor, where the best protection from neutrino oscillations into sterile state has been per- cosmic rays is provided (Fig. 21). The minimum and CRYSTALLOGRAPHY REPORTS Vol. 66 No. 2 2021 INSTRUMENT BASE OF THE REACTOR PIK 211 (а) (b) Helium outlet (trap) Helium inlet Helium outlet Helium inlet (insert) (insert) (trap) Trap counterweight Insert counterweight Helium tank (100 L) Membrane Nitrogen Absorber screen (titanium) Fig. 19. (a) General view of the gravitational trap for measuring the neutron lifetime. (b) Schematics of the experimental setup for measuring the neutron lifetime using magnetic storage: (1) vacuum chamber, (2) switch of UCN motion direction, (3) rotating shutters, (4) magnetic trap, (5) neutron gate, (6) electromagnetic UCN gate, (7) UCN detector, and (8) neutron lid ref lector. (а) (b) 4 5 СN Fig. 20. (a) Schematic of the “neutron β decay” experiment: (1) superconducting solenoid, (2) cylindrical electrode, (3) iron yoke; (4) electron detector, and (5) proton detector. (b) Neutron instrumental complex: (1) supermirror polarizer, (2) monochro- mator, (3) chopper, (4) spin f lipper, (5) magnetic screen, (6) superconducting solenoid, (7) device for measuring beam polariza- tion, and (8) beam trap. maximum distances from the detector to the core will successfully the principles of weak interaction but does be 6 and 15 m, respectively. not answer the question why specifically the left- handed (V–A) version of the theory was chosen. In The preparation of experiment was started on the principle, if there is a left-handed asymmetry, why WWR-M reactor and continued on the SM-3 reactor. should not a right-handed one (i.e., its mirror ref lec- After launching the PIK reactor, it is planned to per- tion) exist? form main measurements on it. The expected count rate of antineutrino events for a detector with a volume The concept of the experiment is as follows. If a of 2 m at a distance of 8 m from the PIK reactor core neutron and its mirror partner are strictly degenerate may amount to ∼800 a day. in mass and there are no external fields, with which they interact differently, their energy states are identi- Search for mirror dark matter in a laboratory experi- ment with UCNs. Because of the violation of the spatial cal and then transitions or neutron–mirror neutron invariance of weak interaction, our world turned out to oscillations may occur. An UCN is stored in the trap be left-handed. The reason for this inequality of left due to the ref lection from its walls; however, if a neu- and right is unknown. The Standard Model explains tron passes to the specular state for the time of f light CRYSTALLOGRAPHY REPORTS Vol. 66 No. 2 2021 212 KOVALCHUK et al. (а) (b) Cladding of technological +14 000 room floor +12 400 Transport corridor Hall of horizontal experimental channels Fig. 21. (a) Schematic arrangement of antineutrino detector on the PIK reactor: (1) PIK reactor core (height 50 cm, diameter 40 cm) and (2) antineutrino detector displacement range: from 6 to 15 m from the PIK reactor core. (b) System for searching neu- tron transitions to the mirror (sterile) state. from one wall to another, the mirror neutron will pass method are widely used in solid-state physics, nuclear through the trap wall without interaction and leave the medicine (for diagnostics and treatment of different trap. A number of experiments were performed to ver- diseases), and molecular-biological applications. ify this hypothesis. The PNPI experiment was carried Currently the leading ISOL complexes—ISOLDE out with a magnetic screen and main elements of the (CERN), TRIUMF (Vancouver, Canada), and new spectrometer for searching the neutron EDM. IGISOL at University of Jyväskylä (Finland)—are Measurements were performed at the ILL on a UCN intensively upgrading their scientific tools. An intense beam prepared at the PNPI for the EDM experiment. work aimed at designing and constructing relatively The oscillation effect was not found, and the limit on moderate ISOL systems for local programs of develop- the oscillation time turned out to be 448 s; the corre- ment in physics of radioactive isotopes is being carried –18 sponding limit on the mixing energy is 1.4 × 10 eV. out in a number of research centers: INFN (Legnaro, This limit can significantly be improved on the PIK Italy), ITEMBA Labs (Stellenbosch, RSA), and reactor due to the use of high-intensity UCN source RAON (Daejeon, Republic of Korea). Note that the (Fig. 21). best functioning ISOL systems have already practically exhausted their potential for studying nuclei more 2.3. Promising Experiments in Nuclear Physics spaced from the β-stability line. The development of the leading ISOL complex SPIRAL2 (GANIL, France) on the PIK Reactor was stopped, and the complex was repurposed. In this Mass-separator laser-nuclear complex IRINA. It is situation the ISOL complex IRINA, which is planned planned to develop a unique complex for producing to be designed on the beam of PIK reactor, is expected and studying exotic short-lived isotopes on the PIK to be unique in the world. reactor within the project IRINA (Russian abbrevia- A schematic arrangement of the IRINA system on tion for the “Study of Radioactive Isotopes on Neu- the channel GEK-5-5' in the experimental hall of the trons”). This complex is expected to have record exit reactor is presented in Fig. 22. The target-ion unit is parameters of neutron-excess nuclei due to the high located in one of the PIK channels with a f lux of 3 × f lux of thermal neutrons on a sample and optimal sys- 13 2 10 n/(cm s) on the target. The heat-resistant ura- tem for nuclei extraction. Study of neutron-deficient nium carbide target contains 4 g U (in the initial and neutron-excess nuclei near the proton and neu- operation stage the mass is reduced to 2 g). Up to tron drip line using the isotope separator on-line (ISOL) method is one of the most important develop- 10 neutron-induced fission events per second occur ment directions in physics of radioactive isotopes. In in the target, as a result of which it is heated to a tem- addition, the radioactive isotopes obtained by this perature above 2000°С. The high temperature pro- CRYSTALLOGRAPHY REPORTS Vol. 66 No. 2 2021 INSTRUMENT BASE OF THE REACTOR PIK 213 System of electrostatic focusing lenses Target (ion source) Mass-separator magnet GEK-6 channel axis Dispersion and collector chambers Pass to PITRAP Reactor water tank Ion-beam distribution chamber Ion channels with electrostatic focusing lenses Neutron detector Tape-moving device Fig. 22. General view of the planned arrangement of IRINA complex in the reactor hall of PIK RC: the reactor is arbitrarily shown in the center. The hot chamber and system of automatic target unit motion are on the left; the mass-separator with three ion channels and receiving stations is on the right; (1) system of matching the mass-separator IRINA with the PITRAP trap and (2) mass-spectrometry complex PITRAP in the PIK RC circular gallery. vides efficient diffusion of fission fragments in the ple, the yield of the “marker” isotope Sn (doubly vacuum bulk of the target-ion unit, where atoms of magic nucleus, remote from the valley of β-stability) desired element are subjected to high-selectivity laser on the ISOL system on the neutron beam of PIK reac- 13 2 235 ionization. The extraction-focusing electrostatic sys- tor with an intensity of 3 × 10 n/(cm s) from a 4-g U tem directs the thus formed ion beam to the probe 11 target will be about 10 isotope particles per second. magnet of mass-separator, where mass-separation The corresponding yields on the functioning IRIS and occurs with subsequent selection and extraction of the 7 8 ISOLDE systems are, respectively, 10 and 10 parti- isotope chosen for study. cles per second. The maximum calculated yield of this To study efficiently the nuclei lying close to the isotope on the next-generation ISOL system SPIRAL-2 neutron stability drip line, it is of key importance to 9 (GANIL, France) would not exceed 10 isotope parti- provide isobaric purity of beams, i.e., selective ioniza- cles per second. tion of isotopes of one chosen element. Selective ion- The use of an ion trap of the ISOLTRAP type on ization of isotopes of a large number of elements can one of the ion channels of the IRINA system will allow be provided only using laser resonance ionization, to measure with high accuracy (few keV) the masses of which was developed and successfully applied on the many nuclei spaced from the β-stability valley to the IRIS system (NRC KI–PNPI); currently, it is also neutron-excess region. The highly sensitive method of used in other ISOL laboratories. This method makes it resonance laser-ionization spectroscopy will be possible to ionize selectively atoms of ISOL-produced applied to measure charge radii and electromagnetic radioactive isotopes of many elements and measure moments of nuclei in the regions that are most inter- with a rather high accuracy the isotope shifts and esting for nuclear physics: region of doubly magic hyperfine splitting of atomic levels of obtained remote nucleus Sn and regions of nuclei with the magic radionuclides. The laser ionization efficiency for number of neutrons N = 50 (neutron-excess isotopes many elements amounts to 10–15%. There is a possi- of Ge, Ga, Zn, Cu, and Ni). In addition, ultrapure bility to obtain isobarically pure isotopic beams of Cu, radionuclides for medical applications will be pro- Ni, Ag, Sn, Mg, Ga, Mn, Fr, Tl, and many other ele- duced on the radioisotope complex IRINA. ments and measure simultaneously their isotope shifts and hyperfine splitting. System for testing fission fragment multiplicity The planned fission rate of 10 fissions per second (FISCO). The system developed is to be located in the on the IRINA system makes it possible to obtain yields hall of inclined channels on the NEC-2 neutron beam of neutron-excess nuclei that multiply exceed the of the PIK reactor (Fig. 23). It is intended for correla- yields of the same nuclei on other systems. For exam- tion studies of nuclear fusion using different methods: CRYSTALLOGRAPHY REPORTS Vol. 66 No. 2 2021 214 KOVALCHUK et al. (а) (b) 12 3 4 5 6 7 8 9 10 56 Fig. 23. (a) General view of the FISCO system on NEC-2 beam: (1) PIK reactor vessel, (2) standard gate (with a pos- sibility of additional arrangement of polarizer), (3) protec- tion of multiplicity detector, (4) assembly of scintillation detectors, (5) beam trap, (6) detector of charged fission Fig. 24. General view of the pneumatic transport system products, (7) photomultipliers, (8) overpass, (9) tool rack, and control rack (prototype). and (10) platform. (b) General schematic arrangement of semiconductor γ spectrometers on an inclined channel of reactor PIK and experimental equipment: (1) neutron and neutron-radiative analysis of the elemental and polarizer, (2) f lipper, (3) collimator, (4) trap, and (5, 6) radi- isotopic composition samples, as well as to measure ation detectors. the interaction cross sections of neutrons with matter. Instrumental neutron-activation analysis (INAA) analysis of the distributions of neutron fission multi- system. This system will make it possible to determine plicity in dependence of the characteristics of fission the contents of Li, B, N, O, F, Ne, Al, V, and Pb in fragments and systems undergoing fusion, as well as samples from their short-lived isotopes, which cannot study of angular and energy correlations for neutrons, be done using conventional methods of neutron-acti- γ quanta, and third particles in fusion. vation analysis. This feature opens up a unique possi- Despite the significant progress in fusion theory, bility of detecting these elements in superhard and one cannot predict the observed values with an accu- heat-resistant alloys (whose properties are determined racy necessary for practical applications. In particular, to a great extent by the content of the aforementioned when calculating reactors and other crucial systems, elements) and investigating geological samples and the error in determining the neutron yield must not biological objects. exceed 0.1%. Attempts are made to develop systems for The measurement complex is designed for INAA detecting masked nuclear materials, based on the prin- based on a γ-radiation spectrometer and a pneumatic ciple of observing different correlations between fis- transport system (Fig. 24). INAA is automated due to sion products. These correlations can be obtained the use of a pneumatic system for transporting samples using the Monte Carlo method within the statistical from the laboratory to the PIK reactor channel for theory. Experimental data on the angular and energy irradiation and backward to the laboratory for further distributions of “instantaneous” fission neutrons and spectrometric studies. The sample delivery time to the γ quanta are tools for debugging and verifying calcula- irradiation zone and backward is shortened, and any tions. This information is important for further study contact between the personnel and radioactive sam- of the nuclear fusion mechanism, because it allows ples under study is excluded. one to determine the main characteristics of f issioning system, such as the parameters of level density for neu- ACKNOWLEDGMENTS tron-excess nuclei, deformations of both fragments We are grateful to the colleagues who took part in the near the “break point,” and the properties of “break” preparation of this review: L.A. Azarova, L.A. Aksel’rod, neutrons. E.V. Altynbaev, A.S. Vorob’ev, A.M. Gagarskii, I.V. Golo- Nuclear radiation spectrometer PROGR AS. The sys- sovskii, V.G. Zinov’ev, I.A. Zobkalo, E.S. Klement’ev, tem consists of a logarithmic neutron guide and two A.I. Kurbakov, I.A. Mitropol’skii, V.N. Panteleev, N.K. Ple- high-purity germanium detectors mounted at its out- shanov, V.V. Runov, S.Yu. Semenikhin, A.E. Sokolov, put (in the hall of inclined channels) (Fig. 23). The S.O. Sumbaev, V.G. Syromyatnikov, V.V. Tarnavich, and intrachannel neutron guide is used to extract the ther- Yu.P. Chernenkov. mal neutron beam, providing a low background level from fast neutrons and γ quanta due to the eff icient use OPEN ACCESS of biological shielding of the reactor. The nuclear radi- This article is licensed under a Creative Commons ation spectrometer PROGRAS is proposed to study Attribution 4.0 International License, which permits use, the structure of atomic nucleus in (n,γ) reactions on sharing, adaptation, distribution and reproduction in any thermal neutrons based on coincidence spectra (γ–γ) medium or format, as long as you give appropriate credit CRYSTALLOGRAPHY REPORTS Vol. 66 No. 2 2021 INSTRUMENT BASE OF THE REACTOR PIK 215 to the original author(s) and the source, provide a link to 21. D. V. Lebedev, M. V. Filatov, A. I. Kuklin, et al., FEBS the Creative Commons license, and indicate if changes Lett. 579, 1465 (2005). were made. The images or other third party material in this 22. C. Sanson, O. Diou, J. Thévenot, et al., ACS Nano 5 article are included in the article’s Creative Commons (2), 1122 (2011). license, unless indicated otherwise in a credit line to the https://doi.org/10.1021/nn102762f material. If material is not included in the article’s Cre- 23. D. Chen, A. Nakahara, D. G. Wei, et al., Nano Lett. 11 ative Commons license and your intended use is not per- (2), 561 (2011). mitted by statutory regulation or exceeds the permitted https://doi.org/10.1021/nl103482n use, you will need to obtain permission directly from the 24. W. Xie, J. He, H. J. Kang, et al., Nano Lett. 10 (9), copyright holder. To view a copy of this license, visit 3283 (2010). http://creativecommons.org/licenses/by/4.0/. https://doi.org/10.1021/nl100804a 25. C. Hardacre, J. D. Holbrey, C. L. Mullan, et al., ADDITIONAL INFORMATION J. Chem. Phys. 133, 074510 (2010). https://doi.org/10.1063/1.3473825 The publication of this Open Access article was funded 26. G. Cheng, P. Varanasi, C. Li, et al., Biomacromole- by Pleiades Publishing. cules 12 (4), 933 (2011). https://doi.org/10.1021/bm101240z REFERENCES 27. G. Gröger, W. Meyer-Zaika, C. Bottcher, et al., J. Am. Chem. Soc. 13 (23), 8961 (2011). 1. A. I. Kurbakov, A. N. Korshunov, A. N. Pirogov, et al., https://doi.org/10.1021/ja200941a Crystallogr. Rep. 66 (2), 267 (2021). 28. M. Yoonessi and J. R. Gaier, ACS Nano. 4 (12), 7211 2. I. A. Zobkalo, Crystallogr. Rep. 66 (2), 216 (2021). (2010). 3. V. L. Aksenov and M. V. Koval’chuk, PIK Reactor Com- https://doi.org/10.1021/nn1019626 plex, Vol. 4: Concept of the Investment Project “Develop- 29. L. Chiappisi, S. Prévost, I. Grillo, and M. Gradzielski, ment of the Instrumental Base of the PIK Reactor Com- Langmuir 30 (7), 1778 (2014). plex” (Izd-vo FGBU PIYaF NITs “Kurchatovskii Insti- https://doi.org/10.1021/la40 4718e tut,” Gatchina, 2015) [in Russian]. 30. V. Raghuwanshi, R. Harizanova, S. Haas, et al., 4. A. M. Balagurov, I. V. Golosovskii, A. I. Kurbakov, et al., J. Non-Cryst. Solids 385, 24 (2014). Diffractometers on the PIK Reactor for Solving Funda- https://doi.org/10.1016/j.jnoncrysol.2013.10.007 mental and Applied Problems (Izd-vo PIYaF, Gatchina, 31. S. V. Grigoriev, S. V. Maleyev, A. I. Okorokov, et al., 2015) [in Russian]. Phys. Rev. B 73, 134420 (2005). 5. F. Hippert, E. Geissler, J. L. Hodeau, et al., Neutron 32. S. Muhlbauer, B. Binz, F. Jonietz, et al., Science 323, and X-Ray Spectroscopy (Springer, 2006). 915 (2009). 6. H. Schober, Neutron Applications in Earth, Energy and 33. A. I. Okorokov, Crystallogr. Rep. 56 (7), 1131 (2011). Environmental Sciences (Springer, New York, 2009), p. 37. 34. A. D. Bianchi, M. Kenzelmann, L. DeBeer-Schmitt, 7. B. T. M. Willis and C. J. Carlile, Neutron Scattering: et al., Science 319 (5860), 177 (2008). Fundamentals (Elsevier, 2013). https://doi.org/10.1126/science.1150600 8. A. Furrer, J. Mesot, and Th. Strassle, Neutron Scattering 35. S. V. Grigor’ev, E. V. Altynbaev, and N. M. Chubova, in Condensed Matter Physics (World Scientific, 2009). Crystallogr. Rep. 66 (2021) (in press). 9. P. W. Anderson, Concepts in Solids: Lectures on the Theory of 36. S. V. Grigor’ev, E. V. Altynbaev, and K. A. Pshe- Solids (Lecture Notes in Physics) (Worlds Scientific, 1963). nichnyi, Crystallogr. Rep. 66 (2020) (in press). 10. N. B. Brandt and V. A. Kul’bachinskii, Quasiparticles in 37. M. T. Rekveldt, W. G. Bouwman, W. H. Kraan, et al., Physics of Condensed State (Fizmatlit, Moscow, 2007) Neutron Spin Echo Spectroscopy. Basics, Trends, and Appli- [in Russian]. cations, Ed. by F. Mezei (Springer, Berlin, 2003), p. 100. 11. D. Pines, Elementary Excitations in Solids (W.A. Benja- 38. M. T. Rekveldt, W. G. Bouwman, W. H. Kraan, et al., min, 1963). Neutron Spin Echo Spectroscopy. Basics, Trends, and Appli- 12. M. I. Kaganov and I. M. Lifshits, Quasiparticles (Nau- cations, Ed. by F. Mezei (Springer, Berlin, 2003), p. 87. ka, Moscow, 1989) [in Russian]. 39. E. G. Iashina, E. V. Velichko, M. V. Filatov, et al., Phys. 13. B. Dorner, Coherent and Inelastic Neutron Scattering Rev. E 96, 012411 (2017). and Lattice Dynamics, Springer Tracts in Modern Phys- 40. E. G. Iashina, W. G. Bouwman, C. P. Duif, et al., ics, Vol. 93 (Springer, Berlin, 1982). J. Phys.: Conf. Ser. 862, 012010 (2017). 14. P. W. Anderson, Basic Notions in Condensed Matter 41. N. K. Pleshanov, L. A. Aksel’rod, V. N. Zabenkin, Physics (Addison-Wesley, 1984). etal., Poverkhn.: Rentgenovskie, Sinkhrotronnye 15. D. Pines, Elementary Excitations in Solids (W.A. Benja- Neitr. Issled., No. 11, 3 (2008). min, 1963). 42. N. K. Pleshanov, Nucl. Instrum. Methods Phys. Res. A 16. Yu. A. Izyumov and N. A. Chernoplekov, Neutron Spec- 872, 139 (2017). troscopy (Energoatomizdat, Moscow, 1983) [in Russian]. 43. V. G. Syromyatnikov, J. Phys. Soc. Jpn: Conf. Ser. 22, 17. F. Mezei, C. Pappas, and T. Gutberlet, Neutron Spin 011005 (2018). Echo. Lecture Notes in Physics, Vol. 601 (Springer, Hei- 44. V. G. Syromyatnikov, RF Patent No. 2680713 (March 30, delberg, 2003). 2018). 18. R. Hempelmann, Quasielastic Neutron Scattering and 45. V. G. Syromyatnikov, RF Patent No. 2624633 (June 21, Solid State Diffusion (Oxford University Press, 2000). 2016). 19. F. Mezei, Z. Physik 255, 146 (1972). 46. A. A. Van Well, Physica B 180–181, 959 (1992). 20. Ch. Franz and Th. Schröder, J. Large-Scale Res. Facil- ities 1, A14 (2015). https://doi.org/10.17815/jlsrf-1-37 Translated by Yu. Sin’kov CRYSTALLOGRAPHY REPORTS Vol. 66 No. 2 2021
Crystallography Reports – Springer Journals
Published: Mar 1, 2021
You can share this free article with as many people as you like with the url below! We hope you enjoy this feature!
Read and print from thousands of top scholarly journals.
Already have an account? Log in
Bookmark this article. You can see your Bookmarks on your DeepDyve Library.
To save an article, log in first, or sign up for a DeepDyve account if you don’t already have one.
Copy and paste the desired citation format or use the link below to download a file formatted for EndNote
Access the full text.
Sign up today, get DeepDyve free for 14 days.
All DeepDyve websites use cookies to improve your online experience. They were placed on your computer when you launched this website. You can change your cookie settings through your browser.