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We studied cytotoxicity and accumulation of boron and lithium by cultured human fibroblasts and human and mouse skin melanoma cell cultures. The cytotoxicity of boron and lithium drugs was assessed by MTT tests in the boron and lithium concentration range of 10-640 μg/ml. Cell viability was significantly reduced after incubation with boron and lithium at concentrations >160 μg/ml. To assess accumulation of boron and lithium, the concentration of elements was measured using inductively coupled plasma atomic emission spectrometry. Melanoma cells more intensively accumulated lithium in comparison with boron. The results indicate the possibility of safe application of lithium salts in concentrations minimally required for successful neutron capture therapy. [ABSTRACT FROM AUTHOR]

Cold neutrons (with energy 10–7–10–4 eV) have found broad application in many areas of modern physics. A new and prospective field of application of low-energy neutrons is the boron neutron capture therapy of oncological illness. This method is based on neutron capture by boron-10, previously accumulated in a tumor, and reaction 10B(n,α)7Li with following escape of energetic α particle and lithium atomic nucleus. The delivery of cold neutrons directly to the area of a malignant tumor can make it possible to increase the localization of the therapeutic dose in the tumor, exclude any impact on healthy cells, and increase the effectiveness of boron neutron capture therapy (BNСT), both in the case of deep-lying malignant tumors and those on the surface. The research described in the article is devoted to the generation of cold neutrons on the VITA accelerator-based epithermal neutron source. This paper describes the cold neutron beam shaping assembly (BSA) that has been designed. The simulation of neutron passage through the BSA performed using Geant4 software is described. The possibility of generating cold neutrons on the VITA accelerator-based epithermal neutron source was demonstrated. [ABSTRACT FROM AUTHOR]

An accelerator-based epithermal neutron source (VITA) has been created and is now operating at the Budker Institute of Nuclear Physics. VITA includes an original tandem electrostatic accelerator (vacuum-insulated tandem accelerator), which produces a monoenergetic beam of protons or deuterons with energies from 0.3 to 2.3 MeV and currents up to 10 mA, and a thin lithium target that generates a powerful neutron flux in 7Li(p, n)7Be and Li(d, n) reactions. The facility is used to develop boron neutron capture therapy and many other applications. Heavy impurities contained in a lithium target are known to significantly decrease the neutron yield and make the target unusable. The purpose of this study was to examine the accumulation of impurities in a thin lithium target. The elemental composition of the sample was determined by ion scattering spectroscopy. The composition of the lithium layer immediately after sputtering on a copper substrate was determined in the experiments. The interaction of lithium with air and the effect of the impurities on the neutron yield were studied. The accumulation of impurities during proton beam irradiation of the target at a beam power density of 1 kW/cm2 and up to 3.4 kW/cm2 was investigated. [ABSTRACT FROM AUTHOR]

The reliable value of the 11B(p,α)αα reaction cross-section is of importance for the proton therapy of cancer, thermonuclear fusion, and nuclear astrophysics. Despite its relevance, the mechanism of the reaction is still an open issue. The goal of the study is to obtain new data on the reaction and to update and clarify the available data in the 0.3–2.15 MeV energy range of the proton beam. The results obtained have shown that the 11B(p,α)αα reaction proceeds via two channels, 11B(p,α1)8Be* and 11B(p,α0)8Be, with unequal cross-sections, which agrees with current conceptions. A thin boron target will be studied later to measure the cross-sections of each channel. [ABSTRACT FROM AUTHOR]

The VITA accelerator neutron source based on a vacuum-insulated tandem accelerator operates at the Budker Institute of Nuclear Physics. At the accelerator source, when transporting a powerful (up to 10 kW/cm2) beam of protons or deuterons to the target, neutrons with a wide range of energies—cold, thermal, epithermal, and fast—are generated. The transported beam or neutron flux is used for conducting research in the field of boron neutron capture therapy (BNCT); measuring the cross section of nuclear reactions (7Li(p, p'γ)7Li, 7Li(p, α)4He, 6Li(d, α)α, 7Li(d, α)5He, 6Li(d, p)7Li, and 7Li(d, α)αn); conducting materials science research together with INP, CERN, and ITER; and for other applications. The creation of a separate compact installation for the generation of fast neutrons is an urgent task; it will allow the treatment of malignant tumors by fast neutrons and the radiation testing of promising materials. The generation of fast neutrons at the existing accelerator neutron source is complicated, because the source of negative hydrogen ions and the bending magnet were designed and produced for the generation and transportation of a proton beam. The installation being created will be designed to generate and conduct a deuteron beam, while the high-voltage and intermediate electrodes of the accelerator will be connected directly to the corresponding sections of the high-voltage power source located inside the gas part of the feedthrough insulator. This paper presents the concept of a compact accelerator source of fast neutrons under development; the results of numerical calculations, modeling, and preliminary testing of the accelerator power supply in air are presented and summarized and further steps of manufacturing and testing of the proposed power supply are formulated. [ABSTRACT FROM AUTHOR]

Ionic substitution is considered to be an effective approach to modify functional characteristics of hexagonal ferrites. To this aim, solid solutions with iso- and aliovalent substitution of iron by aluminum and titanium, respectively, are prepared by the solid-phase synthesis. The influence of the Al3+–Ti4+ substitution on the structure and properties of BaFe12–xAlxO19, BaFe12–yTiyO19 is studied. The prepared solid solutions are studied by scanning electron microscopy and X-ray microanalysis, powder XRD, vibration magnetometry, and differential scanning calorimetry. The crystal structure data confirm that the synthesized samples are characterized by the hexagonal phase, the P63/mmc space group. The samples are shown to consist of 1-10 µm flat hexagonal crystals. The influence of substitution on their magnetic properties is determined. The substitution of Fe3+ magnetic ions by Al3+ and Ti4+ ions decreased the Curie point of the solid solutions. Since magnetic characteristics can be tuned by introducing Al3+ and Ti4+, this effect can be used to control the optimization of magnetic characteristics in BaFe12–xAlxO19, BaFe12–yTiyO19 solutions to solve applied problems. [ABSTRACT FROM AUTHOR]

The expression of marker proteins of acute kidney injury after administration of high doses of lithium carbonate was assessed to evaluate the possibility of lithium use in neutron capture therapy. In mice with implanted skin melanoma B16, the expression of Kim1 (kidney injury molecule 1) and NGAL (neutrophil gelatinase-associated lipocalin) proteins in the kidneys was evaluated immunohistochemically 15, 30, 90, 180 min, and 7 days after peroral administration of lithium carbonate at single doses of 300 and 400 mg/kg. An increase in the expression of the studied proteins was found in 30 and 90 min after administration of 400 mg/kg lithium carbonate, however, 7 days after the drug administration, the expression returned to the level observed in the control group. It can be suggested that single administration of lithium carbonate in the studied doses effective for lithium neutron capture therapy will not significantly affect the renal function. [ABSTRACT FROM AUTHOR]

The magnetic and magnetocaloric properties of the RCo5 polycrystalline alloys (with R = Gd, Tb, Dy, and Ho) are studied experimentally in external magnetic fields of to 3 T. Magnetic measurements show that these compounds are characterized by low coercive force and are going to saturation in low magnetic fields. The magnetocaloric effect of the compounds under study is found to be observed in a wide temperature range, and the TbCo5, DyCo5, and HoCo5 intermetallic compounds exhibit several temperature ranges which are comparable in the value of the effect. The several ranges of the existence of MCE of these ferrimagnetic compounds are due to the series of magnetic phase transitions in them. [ABSTRACT FROM AUTHOR]

This paper describes a method for automating the facility and a method for online data processing that allows an operator and analytical physicists to quickly process information during an experiment without the need for the manual postprocessing of data. The architecture of the automation system was proposed and software was developed for (1) an analysis of signals at the installation with the ability to filter according to user-defined conditions and the ability to display on real-time graphs and (2) displaying the values of various diagnostics with general real-time availability. [ABSTRACT FROM AUTHOR]

A neutron source based on a tandem accelerator with vacuum insulation and a lithium target has been created at the Budker Institute of Nuclear Physics, Siberian Branch, Russian Academy of Sciences. This report provides an overview of the diagnostic tools used at the facility, such as determining the position and size of a beam of negative hydrogen ions using a wire scanner and video cameras, automating experiments on measuring the phase portrait of a proton beam with energies up to 2 MeV using a wire scanner, determining the position and the size of the proton beam on the surface of the lithium target using built-in thermocouples in real time, and automating measurements of the spatial distribution of the absorbed dose components in the water phantom. [ABSTRACT FROM AUTHOR]

The BaFe12–x(Ti,Mn,In,Ga)xO19(x = 1, x = 7) HEOs are prepared by a solid-phase synthesis. Correlations between the chemical composition (degree of Fe substitution), structural parameters, and magnetic characteristics are studied. Magnetic characteristics of the BaFe12–x(Ti,Mn,In,Ga)xO19 (x = 1, x = 7) HEOs are studied in a wide range of fields and temperatures. The measured IR reflectance spectra of the samples contain features caused by phonon vibrations. The dependence of characteristics of phonon lines on the concentration x is qualitatively analyzed; the obtained spectra are compared with those of a single-crystal BaFe12O19 sample. [ABSTRACT FROM AUTHOR]

Large single crystals of high-entropy oxides with the M-type hexaferrite structure, the chemical composition of which can be described by the formula BaFe12–x(Ti, Mn, In, Ga)xO19, are obtained for the first time by spontaneous crystallization from a solution. The actual compositions of the samples are determined: BaFe1.20Ti0.22Mn0.76In0.58Ga0.23O19, BaFe8.71Ti0.44Mn1.16In1.25Ga0.44O19, BaFe7.14Ti0.57Mn1.77In1.79 Ga0.73O19, BaFe5.6Ti0.64Mn2.48In2.52Ga0.76O19. These crystals have a special shape for hexaferrites and are characterized by a fairly uniform distribution of elements in their structure. A significant quantitative difference in the ability of various metal ions to transfer from a melt to a growing crystal is found. A change in the initial ion concentration in the solution has practically no effect on this ability. The influence of crystal compositions on their unit cell parameters is considered. Some increase in these parameters correlates with a decrease in the iron content in the samples. This is mainly due to an increase in the weighted average ionic radius of ions forming the crystals. The configuration mixing entropies within the sublattice formed by Fe, Ti, Mn, In, and Ga for the target compositions and the compositions of actually obtained crystals are calculated and compared. [ABSTRACT FROM AUTHOR]

The results of a study of the magnetocaloric effect (MCE) in Ni2.25Mn0.75Ga0.93Si0.07 alloy are presented in the cast state and in the state after multi-axial isothermal forging (MIF) at 700°C and true degree of deformation e = 3.19. It is shown that as a result of MIF, the initial equiaxed microstructure is transformed into a bimodal one in which large grains 100–200 µm in size are surrounded by a layer of fine-grained microstructure. As a result of MIF, the range of martensitic transformation is slightly shifted to the region of low temperatures by about 5°C. The analysis of phase transformations in the region of room temperatures shows that the intervals of martensitic and magnetic phase transformations are superimposed on each other. The MCE value in a magnetic field of 1.8 T is 0.59ºC in the initial cast state, and as a result of forging it decreases to 0.55°C. [ABSTRACT FROM AUTHOR]

We report a study of the effect of magnetic field on the structural organization and sensory properties of thin titanyl phthalocyanine (TiOPc) layers deposited by vacuum thermal evaporation. It is shown that magnetic field (directed perpendicular to the substrate surface) does not affect the phase composition of the layers which are represented by II-triclinic and I-monoclinic crystal modifications in both cases. The crystallites of both phases demonstrate preferential orientations, the angles between molecular planes and the substrate are 62.53° and 5.30°, respectively. The 2D GIXD study shows that magnetic field significantly improves the crystallinity of obtained thin layers; the conductivity increases by ~10 times, but the sensory response to ammonia does not change. Irradiating the layer obtained in magnetic field by fast neutrons (fluence 3·1014 cm–2) decreases the conductivity by two orders of magnitude. This effect is not observed in the parallel experiment without magnetic field. [ABSTRACT FROM AUTHOR]

A tandem electrostatic accelerator with an original design called a Vacuum Insulated Tandem Accelerator was proposed and developed at the Budker Institute of Nuclear Physics. Unlike conventional tandem accelerators, it does not use accelerating tubes—the high-voltage and intermediate electrodes are made in the form of nested cylinders and are fixed at a single feedthrough insulator. This design of the electrodes made it possible to provide a high rate of ion acceleration (up to 25 kV/cm). The accelerator is equipped with a set of diagnostic tools that provide the long-term stable production of a beam of protons or deuterons with an energy varying from 0.6 to 2.3 MeV and with a current varying from 0.1 to 10 mA. The ion beam is characterized by high monochromaticity, energy stability (0.1%), and high current stability (0.4%). The accelerator is used for in situ observations of the blistering of a metal irradiated with protons; for measuring the cross section of the reactions 7Li(p,p'γ)7Li, 7Li(p,α)α, and 11B(p,α)αα; for developing boron neutron capture therapy for malignant tumors by using neutrons generated in the 7Li(p,n)7Li reaction; for the radiation testing of promising materials using fast neutrons in the 7Li(d,n) reaction; and for other applications. The accelerator became an integral part of the medical neutron source for boron neutron capture therapy: the first facility was put into operation in one of the first six BNCT clinics in the world in Xiamen, China; the next two facilities are being made for the National Center of Oncological Hadron Therapy in Pavia (Italy) and for the Blokhin National Medical Research Center of Oncology in Moscow. In this paper, the design of the accelerator and its features and parameters, as well as the results of studies carried out using the accelerator, are presented and discussed. [ABSTRACT FROM AUTHOR]

One of the charged-particle accelerators with relatively low energy and relatively high current is the vacuum-insulated tandem accelerator proposed for boron neutron capture therapy and planned for use in a number of other applications requiring a more remote location of the neutron-generating target from the accelerator. In this work, the phase portrait of the ion beam and its dependence on the ion beam current and the strength of the magnetic lens focusing the beam of negative hydrogen ions on the input of the accelerator are measured. It is shown that the modernization of the magnetic lens contributed to the reduction of the spherical aberration of the lens and improved the quality of the negative ion beam. It has been established that the ion beam emittance increases with increasing current, and the space charge affects the phase portrait of the ion beam in the low energy transport path. To compensate for the action of the space charge on the phase portrait of the proton beam, the strength of the magnetic lens is changed. The obtained experimental data indicate that the proton beam can be transported to the site of the planned location of the neutron-generating target without adding focusing elements. [ABSTRACT FROM AUTHOR]

The magnetocaloric effect (MCE) in samples of the Gd2In compound has been studied by the direct method in temperature range of 4–240 K in magnetic fields of Bitter coil up to 14 T. The maximum detected value of the inverse MCE at cryogenic temperatures in the 1st-order metamagnetic phase transition (PT) is ∆Tad = − 0.5 K at T0 = 45 K in the field of 1.8 T. The MCE in this temperature range changes sign with increasing of the magnetic field up to 5 T, and the direct MCE is observed with further increasing of the field. The kinetic arrest of the 1st-order metamagnetic PT is observed on the temperature dependence of magnetization in the steady magnetic field of 5 T. The direct MCE in the Curie temperature Tc = 200 K increases with increasing of the magnetic field, and the effect maximum shifts to higher temperatures. The maximum detected value of the direct MCE is ∆Tad = 7.8 K at T0 = 215 K in the field of 14 T. [ABSTRACT FROM AUTHOR]

This study is aimed at developing new experimental methods for investigating the magnetic and thermodynamic properties of solid magnetic materials near phase transitions in high magnetic fields with the use of polycrystalline Gd as an example. The magnetocaloric effect and the magnetization of Gd samples at ambient temperatures in quasi-stationary and pulsed magnetic fields up to 40 kOe are simultaneously measured using two different methods. The results of experiments obtained by different methods are compared, and the effect of eddy currents on the results is evaluated. The maximum value obtained for the magnetocaloric effect in Gd samples is ΔT = 7.3 K at T0 = 299.3 K in a pulsed magnetic field of 40 kOe. [ABSTRACT FROM AUTHOR]

Boron neutron capture therapy (BNCT) can become an instrument for patients with malignant neoplasms of the rectum and colon. Here we evaluate the effectiveness of BNCT performed at the accelerator based epithermal neutron source at G. I. Budker Institute of Nuclear Physics, Siberian Division of Russian Academy of Sciences, in relation to subcutaneous xenografts of human colon adenocarcinoma SW-620 in SCID mice. Utilization of BNCT with boronоphenylalanine (BPA) and sodium borocaptate (BSH), which were injected intravenously into the retroorbital sinus, resulted in a significant decrease in tumor volumes compared to the control group (no radiation). [ABSTRACT FROM AUTHOR]

The Heusler alloys demonstrate magnetically induced strain and magnetocaloric properties, but the mechanical properties are poor. Therefore, in this work, the influence of thermomechanical treatment on the properties of Ni-Mn-Ga-Si Heusler alloys is considered. The effect of multi-axial isothermal forging on functional properties of the Ni2.30Mn0.73Ga0.90Si0.07 alloy at 973 K and true strain (e) of 3.9 is presented. It is shown that a unique two-phase microstructure is formed as a result of forging. The large grains in the size range of 100–200 µm are surrounded by a fine-grained structure. The study of the thermomechanical properties by the three-point bend test has shown that the alloy demonstrates a single-stage reversible deformation of 3.1% at a constant stress of 860 MPa as compared to the same alloy in the as-cast condition which shows 2% at 380 MPa. The specimen demonstrates a reversible deformation of 5% without any degradation during thermal cycling (with a base of up to 4000 thermal cycles) under a stress of 550 MPa and up to 5% with degradation occurring at 700 thermal cycles under a stress of 650 MPa. Thus, forging makes it possible to obtain a material with higher operational properties and greater resistance to fracture during multiple cycles of martensitic transformation. In this case, it is possible to obtain anisotropy of properties equal or close to that of the specimen in the as-cast state. [ABSTRACT FROM AUTHOR]

In electrostatic tandem charged particle accelerators, gas stripping targets are used to convert negative ions into positive ones. Partial ionization of the gas by ions leads to the formation of an undesirable beam of stripping gas ions in the accelerating channels. In this work, the current of a beam of argon ions produced in a tandem accelerator with vacuum insulation was measured by mass spectroscopy. It is shown that the current of argon ions is 2000 times smaller than the current of the proton beam. The reliability of the measurements is provided by visualization of an argon ion beam on the surface of a lithium target and is also confirmed by an experiment with increased gas injection and an estimate of the possible contribution of the proton beam. It is shown that such a small value of the argon ion current does not pose a danger either as a source of additional heating of a lithium target, or as an additional load of a high-voltage power supply, and therefore does not require the previously proposed means for its suppression. [ABSTRACT FROM AUTHOR]

Fundamentals of boron neutron capture therapy of malignant tumors are outlined, and the current status of the development of epithermal-neutron sources on the basis of charged-particle accelerators is surveyed. Attention is additionally given to a neutron source based on a charged-particle accelerator belonging to a new type—a tandem accelerator with vacuum insulation and a lithium neutron-producing target. [ABSTRACT FROM AUTHOR]

The results of measurements of the luminescence spectrum of lithium when it is irradiated with a proton beam with an energy of 2 MeV are presented. The operational diagnostics for monitoring the position of the proton beam on a lithium target, which is used in neutron generation, has been developed and put into operation. [ABSTRACT FROM AUTHOR]

A neutron source composed of a tandem accelerator with vacuum insulation and a lithium target is used to develop the boron neutron capture therapy and other applications. The dependence of the proton beam size on the target surface on the beam current is measured with thermocouples inserted inside the target and with a infrared camera. It is found that there is no appreciable influence of the spatial charge on the proton beam transport to a distance of 5 m from the accelerator to the target, which simplifies the neutron source operation. [ABSTRACT FROM AUTHOR]

The electric strength of ceramic insulators was tested at a dedicated high-voltage vacuum facility and the electric strength of a vacuum-insulated tandem accelerator with redesigned feedthrough insulators was studied. Based on the results of the investigations and the upgrade the voltage in the accelerator was increased from 1.00 to 1.15 MV; the operating mode was achieved without high-voltage breakdowns. [ABSTRACT FROM AUTHOR]

The production of a deuteron beam in a vacuum-insulated tandem accelerator and the generation of fast neutrons from a lithium target have been investigated. The possibility of using a source of fast neutrons for radiation testing of materials and for fast-neutron therapy is discussed. [ABSTRACT FROM AUTHOR]

Processes of the multi-stage decomposition of maleic acid and Li, Na, and Cd maleates in an inert atmosphere are studied via thermal analysis with synchronous analysis of the composition of the released gases. Reaction mechanisms are proposed according to the data on the mass loss stages determined via thermal analysis, gaseous products, and the final solid decomposition products. It is shown that when heated to 700°C, Li and Na carbonates incorporated into the porous carbon matrix are the final products. Above 350°C, cadmium is reduced from oxide to metal and evaporates to form a porous carbon residue as the only product of thermolysis. All carbon products are X-ray amorphous. Maleic acid decomposes completely into gaseous products in the range of 133–239°C. The maleate ion is more stable in the structure of lithium maleate than in free maleic acid, and Na and Cd cations reduce its stability. [ABSTRACT FROM AUTHOR]

Abstract— Diagnostics have been developed for measuring the efficiency of stripping a beam of negative ions in a gas stripping target of a tandem charged particle accelerator. The coefficient of ion-electron emission during the bombardment of copper by protons with an energy of 1 MeV was measured. A bending magnet with a horizontal nozzle was installed, which made it possible to place a Faraday cup and receive a stream of neutrals formed on it as a result of incomplete stripping of negative ions in the stripping target. Diagnostics of the efficiency of the gas stripping target were put into operation on the basis of measuring the current of electrons emitted from the surface of a Faraday cup during its bombardment by a directed stream of neutrals and the proton current by a non-contact current sensor. [ABSTRACT FROM AUTHOR]

Three fragments of the Chelyabinsk meteorite have been investigated by Mössbauer spectroscopy in a temperature range of 300–830 K. They are found to contain iron in the composition of various minerals in different physicochemical and crystallographic states. Anomalous behavior of the temperature dependences of hyperfine magnetic fields on iron nuclei in all fragments is demonstrated. The results obtained are qualitatively explained within the concept of structural magnetic phase transitions, in which iron ions play a role of stabilization centers for new crystal structures in specific temperature ranges. [ABSTRACT FROM AUTHOR]

A method for producing elemental boron nanoparticles with a size of less than 100 nm by ultrasonic dispersion in a liquid medium and subsequent cascade fractionation is described. The resulting boron nanoparticles were used as a target for boron neutron capture therapy (BNCT). According to the results of an experimental preclinical study of BNCT with the synthesized boron nanoparticles, neutron irradiation for 1 h of T98G human glioma cells pre-incubated in a medium with boron nanoparticles (10, 20, and 40 ppm in terms of boron-10 isotope) leads to a significant suppression of cell viability. [ABSTRACT FROM AUTHOR]

The results of experimental investigation into Fe2Ti1 –xVxSn alloys (x = 0, 0.06, 0.15, and 0.2) are presented. It is established from the temperature dependences of the electrical conductivity, Seebeck coefficient, and thermal conductivity that the studied compositions exhibit the transport properties typical of semiconductors, while the partial substitution of titanium atoms by vanadium atoms leads to a change in the conductivity from p-type to n-type; the undoped Fe2TiSn sample possesses the best thermoelectric characteristics. [ABSTRACT FROM AUTHOR]

A modified wire scanner and a new methodical approach were used to measure the profile, current, and phase portrait of a negative hydrogen ion beam injected into a tandem accelerator with vacuum insulation. The effect of the space charge and spherical aberration of the focusing lenses on the negative hydrogen ion beam is revealed. Recommendations are given, whose implementation will make it possible to increase the current of the proton beam from 5 to 10 mA in the accelerator, which is sufficient for boron neutron capture therapy of malignant tumors. [ABSTRACT FROM AUTHOR]

Specific design features and main characteristics of a compact accelerator-based epithermal neutron source for boron neutron capture therapy are described. High quality of the neutron flux generated by the accelerator-based source has been experimentally confirmed. The opportunities for medical use of the accelerator-based epithermal neutron source in oncological centers for boron neutron capture therapy are assessed. [ABSTRACT FROM AUTHOR]

A prototype of a compact sectioned high-voltage source for the modernization of a tandem accelerator with vacuum insulation has been created at the Budker Institute of Nuclear Physics. In contrast to the existing voltage source, it is possible to specify the potential at the accelerating electrodes directly from the rectifier sections, as well as to decrease the accelerator height. This paper presents a new source design and the test results. [ABSTRACT FROM AUTHOR]

A neutron-beam-shaping assembly consisting of a moderator, a reflector, and an absorber is used to form a therapeutic neutron beam for the boron neutron-capture therapy of malignant tumors at accelerator neutron sources. A new structure of the moderator and reflector is proposed in the present article, and the results of a numerical simulation of the neutron spectrum and of the absorbed dose in a modified Snyder head phantom are presented. The application of a compositemoderator and of a composite reflector and the implementation of neutron production at the proton energy of 2.3MeVare shown to permit obtaining a high-quality therapeutic neutron beam. [ABSTRACT FROM AUTHOR]

The magnetic and magnetocaloric properties of NiMnIn, NiMnIn, and NiMnInCo Heusler alloys are investigated. The magnetocaloric effect (MCE) is experimentally measured using the direct method with the help of different protocols. The phase transformation temperatures and the latent heat of metamagnetostructural transitions are determined from the temperature dependences of magnetization and via differential scanning calorimetry. In the case of NiMnIn and NiMnIn alloys, the temperature shift of martensitic transformation induced by external magnetic field is found. It is demonstrated that, in the NiMnInCo alloy, added Co atoms raise the temperature of structural and magnetic phase changes and enhance the MCE. In addition, it is revealed that the MCE depends on measurement protocols near the first-order phase transition. [ABSTRACT FROM AUTHOR]

Suppression of parasitic electron flows and positive ions formed in the beam tract of a tandem accelerator with vacuum insulation allowed a more than threefold increase (from 1.6 to 5 mA) in the current of accelerated 2-MeV protons. Details of the modification are described. Results of experimental investigation of the suppression of secondary charged particles and data on the characteristics of accelerated proton beam with increased current are presented. [ABSTRACT FROM AUTHOR]

For the development of boron neutron-capture therapy of malignant tumors, a source of epithermal neutrons on the basis of a tandem accelerator with a vacuum insulation and a lithium target was created and launched. With the aim of optimizing the neutron-producing target, various structure materials were irradiated with a proton beam. The results obtained bymeasuring the dose rate and radiation spectrum upon the absorption of 2-MeV protons are presented, and the choice of tantalum for an optimum material of the target substrate was explained. [ABSTRACT FROM AUTHOR]

A new type of accelerator, namely, an electrostatic tandem accelerator with vacuum insulation, being distinguished by a high acceleration rate of charged particles and a large surface area of accelerating electrodes, was proposed, manufactured, and put into operation to obtain a proton beam with a 2-MeV energy and a direct current up to 10 mA. The influence of breakdowns on the electric strength of high-voltage components of the accelerator is studied in the work. [ABSTRACT FROM AUTHOR]

The time-of-flight technique with a new method for generating short radiation bursts has been used to measure the neutron spectrum of the accelerator-based source with a stationary proton beam. Specific problems arising thereby and methods for solving them are described. The measured spectrum of neutrons in the reaction Li( p, n)Be at a proton energy of 1.915 MeV is presented and compared to the calculation. This spectrum is shown to comply with the requirements for the neutron beam used in neutron capture therapy. [ABSTRACT FROM AUTHOR]

The dark currents flowing in the high-voltage gaps of an electrostatic tandem accelerator with vacuum insulation and the effects associated with their occurrence are investigated. This accelerator, featuring a fast rate of charged particle acceleration and a large surface area of the accelerating electrodes, has been designed to produce a proton beam with an energy of 2 MeV and a constant current of up to 10 mA. [ABSTRACT FROM AUTHOR]

We studied in vitro effect of epithermal neutrons in various doses on viability of glioblastoma U87 tumor cells. Increasing the dose from 1.9 to 4.1 Sv promoted cell death. Cytofluorimetric analysis revealed no activation of apoptosis in the irradiated cells, which attested to necrotic death of the tumor cells exposed to epithermal neutron radiation. [ABSTRACT FROM AUTHOR]

An epithermal neutron source that is based on a vacuum insulation tandem accelerator (VITA) and lithium target was created in the Budker Institute of Nuclear Physics for the development of boron neutron capture therapy (BNCT). A stationary proton beam with 2 MeV energy and 1.6 mA current has been obtained. To carry out BNCT, it is necessary to increase the beam parameters up to 2.3 MeV and 3 mА. Ways to increase the parameters of the proton beam have been proposed and discussed in this paper. The results of the experiments are presented. [ABSTRACT FROM AUTHOR]

An epithermal neutron source based on a tandem accelerator is being constructed at the Budker Institute of Nuclear Physics for use in neutron capture therapy at a cancer clinic. A lithium neutron-generating target obtained by deposition of lithium onto the target substrate is one of the key elements of the facility. The effect of residual gas on the lithium layer composition has been investigated using a secondary-ion mass spectrometer. [ABSTRACT FROM AUTHOR]

Investigations of new ferromagnetic shape-memory Ni-Mn- Z Heusler alloys ( Z = In, Sn, Sb) are reviewed. Experimental data are described and explained on the assumption that these alloys undergo a phase transition from the ferromagnetic to the antiferromagnetic state (metamagnetic transition). The results of theoretical studies of the phase diagrams of these alloys are considered with regard to the possible change in the character of magnetic ordering (from ferromagnetic to antiferromagnetic) and interaction of the structural martensitic transformation with the metamagnetic transition. [ABSTRACT FROM AUTHOR]

The phase diagrams of magnetically ordered Heusler alloys with the inversion of the exchange interaction have been studied using the phenomenological Landau theory of phase transitions. It has been shown that the shape of the phase diagrams in these alloys depends on the magnitudes and signs of the phenomenological parameters in the Landau functional. At certain magnitudes and signs of the parameters of the Landau functional, the phase diagrams have thermodynamic paths that allow one to explain the experimentally observed sequences of the phase transitions in the Heusler alloys. [ABSTRACT FROM AUTHOR]

The status of the design work on an electrostatic tandem-accelerator with vacuum insulation for 2.5 MeV protons and up to 40 mA constant current is reported. This machine is to be used for solving problems of neutron therapy and the detection of explosives by nuclear-resonance absorption of γ-rays. [ABSTRACT FROM AUTHOR]

A hot target plasma is obtained in the end cell of the AMBAL-M device with the use of an end gas-discharge plasma source. A fairly high longitudinal electron current flowing from the plasma source to the plasma receiver is detected experimentally. The electron current is studied in the region in front of the input magnetic mirror, where the longitudinal electric field is directed outward from the mirror. Different models for plasma description are considered, and possible plasma instabilities are discussed. It is shown that a fairly high longitudinal electron current in the region where the electric field accelerates electrons results in the generation of the flow of fast electrons responsible for the current in the mirror system. © 2000 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]

The electron distribution function over longitudinal energies in the startup plasma of the end cell of the AMBAL-M device is measured with a small-size movable electrostatic analyzer. It is found that, in the region where a substantial longitudinal current flows, the electron distribution function over longitudinal energies has a plateau in the 150–350-eV energy range. © 2000 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]

A proton beam (2 MeV and 1.6 mA) has been obtained on a tandem accelerator with vacuum insulation. Experimental results are given that outline the reasons for current limits, and approaches to increasing the current of a proton beam are proposed. [ABSTRACT FROM AUTHOR]