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The performance of a multipurpose synchrotron spectrometer is diversified by installing additional equipment for the studies of diffraction in the Debye–Scherrer geometry. The design of X-ray optics and technical characteristics of the spectrometer are described. Diffraction patterns for polycrystals detected in both the forward and backward hemispheres are illustrated.

The performance of the Kurchatov Institute’s multiporpose synchrotron spectrometer is diversified by adding the equipment for the X-ray fluorescent element analysis. The X-ray optical focusing system of the spectrometer is described. The analysis results for the copper, lead, and gold-nanofilm samples are reported.

The improved X-ray optical scheme, the system of registration, and the measurement procedure of the multifunctional synchrotron radiation spectrometer in the dispersive EXAFS mode are described. The results of the spectrometer energy resolution measurements are given. The advantages and disadvantages of traditional and dispersive EXAFS spectrometers are analyzed. Examples of EXAFS spectra measured in the dispersive mode are given.

Equipment is constructed, a technique is developed, and experimental results on Debye-Scherrer diffraction in the backscattering geometry are obtained. A special program for diffraction ring processing is developed. The prospects for use of this technique for materials science purposes are discussed.

A technique for Debye-Scherrer diffraction in the backscattering geometry is developed at the Kurchatov Synchrotron Radiation source. It is shown that the sensitivity of the method to a relative change in the lattice constant is higher by two orders of magnitude than that in the forward-scattering geometry. The requirements for experimental apparatus are discussed.

The energy dispersive EXAFS spectrometer was created by a joint effort of the Joint Institute for Nuclear Research, Belarus State University, the Kurchatov Institute Russian Research Center, and the Institute of Crystallography of the Russian Academy of Sciences. A brief description of the spectrometer is given. The first results of a complex adjustment of the spectrometer units on the synchrotron radiation beam are presented.

Equipment and technology for producing X-ray refractive lenses from polymethyl methacrylate are described. Each single lens has a spherical profile with a radius of 2.38 mm. A compound lens is composed of 235 single lenses. The focal length of the compound lens for 14-keV X-ray photons is 4.8 m. The lenses developed thereby have been tested on the synchrotron radiation source of the Scientific and Engineering Complex at the Kurchatov Centre of Synchrotron Radiation and Nanotechnologies. The advantages and the drawbacks of the parabolic and spherical lenses are discussed.

The REFRA station developed, fabricated, and put into operation at the Kurchatov Synchrotron Radiation Center is described. The station is placed on beamline 5.6 of the big storage ring. The station consists of a vertical beam position monitor, an operating shutter, vertical and horizontal slits for the white beam, a monochromator, an alignment stage, an intensity monitor, an EXAFS spectrometer unit, a diffractometer unit, detectors, and a data control and acquisition system. The station operating energy range is 5–30 keV. The station is fully-automated and has been operating with the SR beam since spring 2005. The station units can be reproducibly mounted on the SR beam to provide various research configurations.

The paper presents fluorescence EXAFS spectrometer developed at Kurchatov Synchrotron Radiation Center. The spectrometer allows one to study elements from Cr ( Z = 24 ) up to Bi ( Z = 83 ) . The important peculiarity of the spectrometer is the possibility to study thick undisturbed samples, retaining their history—annealing, seasoning, hardening and so on. The spectrometer consists of beam position monitor, channel cut monochromator, intensity monitor, sample holder and detector. The detectors consist of photomultipliers with scintillators. The EXAFS spectra of Ni–Cr alloys are measured and processed as the examples.

A method for automatically controlling commercial computer codes is described. The coupling of the automation system of the EXAFS spectrometer controlled by a DOS-operated computer that we developed and the commercial program of a semiconductor-detector control installed on a Windows-operated computer is given as the example. The described complex system is used for the automation of the intermediate processing of amplitude spectra while measuring EXAFS spectra at the Kurchatov Synchrotron Radiation Source.

A method using intermediate processing of amplitude (energy) spectra is described. The method is an alternative to the known differential discrimination method, which is widely applied in measurements of EXAFS spectra and in Mossbauer and diffraction measurements. The method is efficient in cases in which the radiation spectrum contains lines poorly resolved in the used detector. For example, if weak fluorescence of a low-concentration impurity is detected in a sample against the background of intense fluorescence of the matrix, the described method allows one to noticeably improve the quality of the obtained information.

The electron beam size of the 2.5-GeV storage ring of the Kurchatov Synchrotron Radiation Source was measured using a fixed edge screen. The obtained vertical beam size of 190 μm and the corresponding calculated value of 198 μm (for 2% betatron coupling) almost coincide within the experimental error.

The station is situated on big Kurchatov storage ring. The station has stabilizer of vertical SR beam position, SR shatter, slits, SR monochromator, adjustment table, intensity monitor, EXAFS-spectrometer block, diffractometer block, 2d micro detector. The station is fully automated. Energy band of the station is 5–30 keV. All blocks of the station can be reproducible located on SR beam, giving one the possibility to realize different experimental modes. The station is in full use since spring 2005.

Electron beam size of the storage ring at 2.5 GeV was measured by means of fixed edge screen. Obtained vertical electronic beam size of 190 μm practically agree with corresponding calculated value of 198 μm (for 2% relation of betatron coupling) within error of measurement.

NQR andμSR investigations of the local magnetic field inα-Bi2O3 were performed. In theNQR experiments onα-Bi2O3 which is usually considered as diamagnetic, the splitting of the spectral lines revealed a local field on the bismuth nuclei. The internal magnetic field obtained byμSR significantly exceeds the dipole field from Bi nuclear magnetic moments. A possible source of the local magnetic fields is partial covalent bonds inα-Bi2O3.

TF and ZFμSR-investigations were performed on high purity CuO powder. By TF measurements a phase transition to the ordered state was observed at 227K. A commensurate-incommensurate phase transition was detected at 213K by ZF measurements. In the commensurate phase we observed the Larmor precession. Four signals were detected below 55K, but by increasing temperature above 190K, precession became having only one component. This fact may be explained by muons tunneling between equivalent sites. In the incommensurate phase the Larmor precession was not detected because of too large damping.

Zero field muon spin rotation and magnetic susceptibility experiments on investigation of magnetic properties of cuprateY2Cu2O5 have been performed in the temperature range 4.2–30 K. Transverse fieldμSR-experiments have been also carried out in order to obtain accurate information about transition temperature and to study the influence of the external magnetic field. Our data show that two magnetic phase transitions occur inY2Cu2O5 with lowering temperature. Upper Neel temperatureTN=13 K is consistent with previous experimental data. We obtained the temperature dependence of the local magnetic field on the muonBμ(T) in the antiferromagnetic phase.Bμ(T) reveals a peculiarity (some change of the slope) near the temperatureTN=7.5 K, which can be interpreted as an additional magnetic phase transition caused by a change in magnetic ordering of the copper subsystem. Applying a small external magnetic field 50 Oe leads to smearing of the peculiarity inBμ(T) dependence.

ZF, LF and TF μSR experiments with antiferromagnetic (AF) ceramical samples La2−xSrxCuO4−y have been performed in the temperature range 10–300 K. Zero field muon spin polarization functions obtained below the Neel temperature clearly show a nonzero initial precession phaseϕ∼-−0.35 rad. We propose an explanation based on existence of the dynamical magnetic fields on the muon.

The dependence of the residual polarization of negative muons in p-type Si on temperature in the 4.2–270 K range has been investigated. Measurements were carried out in external magnetic field of 0.08 T transverse to the muon spin. The impurity concentration in the sample was 2 · 1013 cm−3. Muon spin relaxation was observed at temperatures below 30 K. The relaxation rate atT=30 K is equal to 0.18±0.08μs−1. The relaxation rate grows with the decrease of temperature and at 4.2 K exceeds 30μs−1. The value of the residual polarization at zero timeP(t=0) is constant within the investigated temperature range.

A zero magnetic field muon spin rotation study of α-O2 (antiferromagnetic phase of solid oxygen) in the temperature range 10–24 K is presented. Static magnetic order has been observed below the α-β transition temperature. The temperature dependence of the muon precession frequency exhibits a behavior characteristics of the two-dimensional Heisenberg spin-1 system with anisotropy parameter α ∼ 10−2.

Results on the systematics of the magnetic penetration depth ${\ensuremath{\lambda}}_{\mathit{a}\mathit{b}}$ in the high-temperature superconductors ${\mathrm{Bi}}_{2}$${\mathrm{Sr}}_{2}$${\mathrm{Ca}}_{1\mathrm{\ensuremath{-}}\mathit{z}}$${\mathrm{Y}}_{\mathit{z}}$${\mathrm{Cu}}_{2}$${\mathrm{O}}_{8+\mathrm{\ensuremath{\delta}}}$ (z=0,0.1,0.2,0.3,0.4,0.45) and ${\mathrm{Bi}}_{2\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Pb}}_{\mathit{x}}$${\mathrm{Sr}}_{2}$${\mathrm{CaCu}}_{2}$${\mathrm{O}}_{8+\mathrm{\ensuremath{\delta}}}$ (x=0.15,0.30,0.70) are reported from muon-spin-rotation measurements on polycrystalline samples with known oxygen excess \ensuremath{\delta}. In determining ${\ensuremath{\lambda}}_{\mathit{a}\mathit{b}}$ various additional sources for inhomogeneous internal field distributions, besides the one arising from the flux-line lattice, have been critically taken into account. The most important one arises from a type of powder broadening due to the anisotropy of the field-cooled magnetization. It is found that ${\ensuremath{\lambda}}_{\mathit{a}\mathit{b}}$ in the Y-doped compounds correlates in the expected manner with the nominal hole-carrier concentration p (${\ensuremath{\lambda}}_{\mathit{a}\mathit{b}}^{\mathrm{\ensuremath{-}}2}$\ensuremath{\propto}p) while the Pb-doped compounds ${\ensuremath{\lambda}}_{\mathit{a}\mathit{b}}$ is practically independent of p. It is concluded that Pb doping (valence state is +2) does not increase the density of free charge carriers in agreement with results from Hall-effect measurements. No correlation between ${\ensuremath{\lambda}}_{\mathit{a}\mathit{b}}^{\mathrm{\ensuremath{-}}2}$ and ${\mathit{T}}_{\mathit{c}}$ in the manner seen in the 1:2:3 family is found in the present case.

Muon precession parameters in liquid oxygen as well as α-, β- and γ-phases of crystalline oxygen have been measured in the temperature range 10–90 K. It was found that the muon polarization P =1 in liquid O 2 , γ-O 2 and β-O 2 . The local field at the muon site has been measured in the antiferromagnetic α-phase of oxygen ( B 0 =1.2 kG). The analysis of the data obtained shows that about 40% of the muons in oxygen form a paramagnetic complex (presumably MuO 2 or O 2 Mu + ) and about 60% of them form a diamagnetic compound.

After conversion of the LNP JINR phasotron new opportunities have been opened for μSR-research. A new round of investigations has begun since 1987. In this paper we present the summary of the results achieved and give some prospects for future investigations.

The zero field μSR-method has been used to study the magnetism in the disordered magnetic alloy Fe82−xNixCr18 near the three-critical, pointx=25. The dynamic and static local field distributions are analyzed. The difference between spin-glass states obtained either from the paramagnetic or after the double transition is discussed.

High temperature superconductors HoBa2Cu3O7−δ (T c ≅93 K), Ho0.5Y0.5Ba2Cu3O7−δ (T c ≅93 K) and ErBa2Cu3O7−δ (T c ≅95 K) were investigated by the zero-field μSR-technique. The muon spin depolarisation rate connected with the fluctuation frequency of rare-earth ion magnetic moments was measured. It was found that the samples with holmium show a fast increase of the muon spin depolarisation rate at temperatures below 20 K, while in ErBa2Cu3O7−δ the depolarisation rate remains low in the whole temperature region studied (4.2 K-270 K). The sharp difference between the behaviours of the muon spin depolarisation rate may be explained by the difference between the ground state of Ho3+ and Er3+ ions in the crystalline field of the lattice.

We present the results of investigations of superconducting niobium and high temperature ceramical superconductor La1.9Sr0.1CuO4 by the μSR technique. The experiments with the niobium sample confirm high reliability of the μSR-technique in determining such characteristics of type II superconductors asTc,Hc1,Hc2, the magnetic field penetration depth λ, and the critical current densityJc. The analysis of the field dependencies of the distribution width and mean value of the magnetic fields on the muon when the samples are magnetized is carried out. A qualitative difference in the behaviour of the magnetic field distribution width in Nb and LaSrCuO is revealed. Whilst the niobium data are well described in the frame of the critical state model, application of a similar approach to the high-Tc superconductor does not give a satisfactory description of our experimental results.

The temperature dependences of parameters of the muon spin relaxation in liquid and crystalline nitrogen have been studied. It has been established that in condensed nitrogen there takes place a fast depolarization of muons. An anomalous behaviour of the amplitude and phase of muon precession is found in the vicinity of the orientation phase transition in solid nitrogen. It has been shown that muon spin relaxation parameters in nitrogen do not change at reduction of the oxygen impurity content from 0.7·10−4 to 10−6. The fast depolarization of muons in condensed nitrogen is apparently due to the formation of muonium atoms. To explain the phenomena observed, a model of the muonium chemical reaction is proposed. The initial phase of the muon precession has been measured as a function of the perpendicular magnetic field to determine the state of short-lived muonium in nitrogen. It has been determined that muonium in nitrogen is in an excited state. Consideration of the nuclear hyperfine interaction of muonium in condensed nitrogen makes it possible to give a qualitative explanation for the temperature dependence of the initial amplitude of the muon precession.

We report the results of μSR investigations of the ceramic samples La2-xSrxCuO4-σ (x=0.1, 0.15, 0.25) and ReBa2Cu3O7-σ (Re=Er, Ho, Y0.5Ho0.5) in the external magnetic field 0–800 Oe. The measurements were performed by the ZFC and FC methods. The irreversibility effects were studied at several temperatures by measuring the mean value and the width of the magnetic field distribution on the muon in the step by step procedure of increasing and subsequent decreasing of the external field. The temperature dependences of the magnetic penetration depth perpendicular to the basal plane λ⊥ were obtained. For the lanthanum sample with 0.15 of Sr its value at the zero temperature is λ⊥ (0)=2400 A, for Er-Ba-Cu-O λ⊥ (0)=1600 A.

The muon spin relaxation was measured in the high-Tc superconductors Bi2(Sr1.3Ca0.7)CuO6.2, Bi2Sr2CaCu2O8.16, (Bi1.85Pb0.15)Sr2CaCu2O8.18 and (Bi1.83Pb0.25)Sr1.97Ca1.97 Cu3.07Ox. The data were analysed in order to determine the London penetration depth lambda ab parallel to the basal plane. In all investigated samples lambda ab revealed a temperature dependence which can be explained with the framework of conventional BCS theory in the weak coupling limit.

Zero field muon spin relaxation measurements of the ceramic high-Tc superconductors HoBa2Cu3O7-σ, Oc≃93 K) and ErBa2Cu3O7-σ (Tc≃95 K) reveal the sharp difference between the behaviours of the muon spin relaxation rate at temperatures below 20K. This fact may be explained by assumption that the frequency of fluctuations of Er magnetic moments exceeds by far the fluctuation frequency of Ho in 1-2-3 compounds.

μSR investigation of magnetic properties of Y 2 Cu 2 O 5 has been performed in the temperature range 4.2–30 K. Besides the known magnetic phase transition at T N1 = 13 K the peculiarity in the temperature dependence of the local magnetic field on muon was observed near T N2 = 7.5 K. The applying of a small external magnetic field of 50 Oe leads to smearing of this peculiarity.

We have performed the muon spin rotation (SR) measurements of the magnetic penetration depth λ in the superconducting ceramical samples BaPb1−xBixO3 with the bismuth content x=0.22, 0.24, 0.26. The magnetic penetration depth has the low temperature value λ(4.3K) = 7900A for x=0.24. The temperature dependence λ(T)−2 have linear behaviour without any saturation down to the temperature 4.3 K.

Muon spin relaxation and neutron diffraction measurements were performed in Y and Pb substituted Bi-2212 superconductors in order to study the correlation between T c and hole density. We observe first an increase of both T c and the superconducting carrier density via hole transfer, but subsequently (at higher “doping”) more and more holes are prevented from forming superconducting pairs.

The superconducting carrier density n , was measured by means of μ + SR spectroscopy in the mixed phase of a series of polycrystalline Bi-based 2212 superconductors with different substitution of Bi 3+ by Pb 2+ . In exactly the same samples the effective valence per Cu-atom V ( Cu ) was determined by neutron powder diffraction. We observed that n , and V ( Cu ) are not proportional to each other in the heavily doped region. This behavior is interpreted as evidence that the carriers become more and more localized with increasing lead content.

The muon depolarization rate σ was measured by Transverse Field μSR and field cooling procedure in an applied magnetic field of 200 mT. By assumption that the muon depolarization rate σ in the 80 K- phase in normal state is small, data from the temperature interval 85–100 K were used to estimate the magnetic field penetration depth in the 110 K- phase of the lead-free ceramic Bi-Sr-Ca-Cu-O superconductor.

A method for measuring the time scale for positive muon diffusion in helicoidally ordered antiferromagnets is proposed. The experiment shows that the muon diffusion in dusprosium over the temperature interval 100–175 K is a tunneling process.

By means of the uSR method, the critical temperature Tk=(17.41 0.05) K and the inhomogenety of the internal magnetic field in Nb3Al in the mixed state for two values of external magnetic fields H=62 Oe and H=285 Oe over the temperature range 9–17 K were measured.

Muon and muonium spin rotation and relaxation parameters were studied in liquid and solid xenon. The small diamagnetic fraction (∼10%) observed in condensed xenon is believed to be Xeμ + . The muonium hyperfine frequency was measured for the first time in liquid Xe and was found to be in agreement with the vacuum value. A nonmonotonic temperature dependence of the muonium relaxation rate probably indicates that muonium diffusion in solid Xe is of quantum nature.

The ceramical system La2-xSrx CuO4 was investigated in the temperature range 4.4–270 K. At the concentrations of Sr x=0.0 and 0.01 the formation of the antiferromagnetic state was observed. The results of the investigations of the magnetic ordering in the fluctuating formation region are given. Investigation of the sample with x=0.07 at the temperature T < 13K confirmed the existence of the spin glass state. The values of the magnetic penetration depth at different temperatures for the superconducting samples are given. The influence of the pinning on the magnetic field distribution in the mixed state of the superconductor is discussed.

It was shown that at T=12 k the dipole relaxation of a positive muon in Nb3Al in the zero external magnetic field is well described by the Kubo-Toyabe function for the static distrubution of the dipole magnetic fields in the absence of muon diffusion. The superconducting state of Nb3Al was used for eliminating the background from muons stopped in the cryostat walls.