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A compact accelerator-based neutron source has been proposed and created at the Budker Institute of Nuclear Physics in Novosibirsk, Russia. An original vacuum insulated tandem accelerator (VITA) is used to provide a proton/deuteron beam. As a result of scientific research and modernization, the power of the ion beam was increased, an operation mode without high-voltage breakdowns was achieved, and the operation of the accelerator in a wide range of changes in the energy and current of ions was ensured. The proton/deuteron beam energy can be varied within a range of 0.6-2.3 MeV, keeping a high-energy stability of 0.1%. The beam current can also be varied in a wide range (from 0.3 mA to 10 mA) with high current stability (0.4%). VITA is used to obtain epithermal neutrons for the development of boron neutron capture therapy, thermal neutrons for the determination of impurities in ITER materials by activation analysis method; fast neutrons for radiation testing of materials; 478 keV photons to measure the 7Li(p, p’g)7Li reaction cross section, etc. VITA is planned to be used for boron imaging with monoenergetic neutron beam, for characterizing of neutron detectors designed for fusion studies, for in-depth investigation of the promising 11B(p, alfa)alfa alfa neutronless fusion reaction, for studying the crystal structure of materials by neutron diffraction, etc., Proceedings of the 27th Russian Particle Accelerator Conference, RuPAC2021, Alushta, Russia

A neutron source for boron neutron capture therapy based on a vacuum-insulated tandem accelerator has been developed and operates at Budker Institute of Nuclear Physics. Conducting a ~10 mm proton beam with a power of up to 20 kW through a system of accelerating electrodes and 16 mm argon stripping tube is not an easy task. Any mistake made by operator or a malfunction of the equipment responsible for the correction of the beam position in the ion beam line can lead to permanent damage to the accelerator. To determine the position of the proton beam inside the argon stripping tube, optical diagnostics have been developed based on the Celestron Ultima 80-45 telescope and a cooled mirror located at an angle of 45 degrees to the beam axis in the straight-through channel of the bending magnet. The cooled mirror also performs the function of measuring the neutral current due to the electrical isolation of the mirror and the extraction of secondary electrons from its surface. The luminescence of a beam in the optical range, observed with the help of the developed diagnostics, made it possible for the first time to determine beam size and position inside the stripping tube with an accuracy of 1 mm. The light sensitivity of the applied optical elements is sufficient for using a shutter speed from 2 to 20 ms to obtain a color image of the beam in real time. This makes it possible to realize a fast interlock in case of a sudden displacement of the beam., Proceedings of the 27th Russian Particle Accelerator Conference, RuPAC2021, Alushta, Russia

For the development of a promising method for the treatment of malignant tumors - boron neutron capture therapy - the accelerator-based epithermal neutron source has been proposed and created in the Budker Institute of Nuclear Physics. After the acceleration phase, a proton beam with an energy of up to 2.3 MeV and a current of up to 10 mA is transported in a high-energy beam line. With a beam size of 1 cm², its power density can reach tens of kW/cm². Diagnostics of the size of such a powerful beam is a nontrivial task aimed at increasing the reliability of the accelerator. The paper presents such diagnostics as: 1) the use of the blister formation boundary during the implantation of protons into the metal; 2) the use of thermocouples inserted into the lithium target; 3) the use of the melting boundary of the lithium layer when it is irradiated with a beam; 4) the use of the activation of the lithium target by protons; 5) the use of video cameras; 6) the use of an infrared camera; 7) the use of the luminescence effect of lithium when it is irradiated with protons; 8) the use of collimators with a small diameter of 1-2 mm; 9) the use of the method of two-dimensional tomography*., Proceedings of the 27th Russian Particle Accelerator Conference, RuPAC2021, Alushta, Russia

For the development of a promising method for the treatment of malignant tumors - boron neutron capture therapy - the accelerator-based epithermal neutron source has been proposed and created in the Budker Institute of Nuclear Physics. Argon ions formed during stripping of a beam of negative hydrogen ions to protons are accelerated and, in parallel with the proton beam, are transported along the high-energy beam line of the facility. Depending on the relative number of argon ions, their effect can vary from negligible to significant, requiring their suppression. In this work, the current of argon ions reaching the beam receiver in the horizontal high-energy beam line of the accelerator was measured. It was determined that the argon beam current accompanying the proton beam is 2000 times less than the proton beam current. This makes it possible not to apply the proposed methods of its suppression., Proceedings of the 27th Russian Particle Accelerator Conference, RuPAC2021, Alushta, Russia

For the development of boron neutron capture therapy - an accelerator source of epithermal neutrons has been proposed and created at the Budker Institute of Nuclear Physics (Novosibirsk, Russia). For future therapy it is necessary to ensure the transportation of a proton beam in a high-energy beam line at a distance of 10 meters. For this purpose, using a movable diaphragm with a diameter of 1 mm, mounted on a three-dimensional vacuum manipulator, and a wire scanner, the phase portrait of the proton beam was measured. The software for remote control of the movable diaphragm and data processing of the wire scanner was developed. An algorithm for processing a series of measurements was developed to reconstruct the image of the phase portrait of the beam and calculate the emittance. This work describes in detail the features of the measuring devices, control algorithms and data processing. An experiment was carried out to measure the phase portrait and emittance of a proton beam with an energy of 2 MeV and a current of up to 3 mA. A beam of neutral particles was also measured. The effect of a bending magnet on the focusing and emittance of the beam is studied. The invariant normalized emittances calculated from the measured phase portraits make it possible to assert that the beam can be transported over distances of about 10 meters without changes in the current geometry of the high-energy beam line., Proceedings of the 27th Russian Particle Accelerator Conference, RuPAC2021, Alushta, Russia

The accelerator-based epithermal neutrons source, proposed and created in the Budker Institute of Nuclear Physics, provides the generation and formation of a neutron flux suitable for testing the boron neutron capture therapy of malignant tumors. The paper presents and discusses the results of studies using activation techniques. Using activation foils from the SWX-1552 kit (Shieldwerx, USA), an iterative grid method for reconstructing the neutron spectrum was tested. It was found that the use of activation foils for determining the spectrum of epithermal neutrons is questionable, since the main part of the interaction falls on the high-energy part of the spectrum, instead of the resonance of the foil. The number of neutrons is equal to the number of activated beryllium-7 nuclei (it has been proven by measurements that beryllium-7 is not sputtered from the lithium layer). The neutron yield was monitored by registering gamma quanta from the 7Li(p, n)7Be reaction. Depending on the number of registered gamma quanta, recalculation was made for the amount of activated beryllium. In this paper it was measured the number of neutrons depending on different geometries, different parameters of the proton beam and target material, there is a good agreement with the theory., Proceedings of the 27th Russian Particle Accelerator Conference, RuPAC2021, Alushta, Russia

At Budker Institute of Nuclear Physics it was proposed and developed a source of epithermal neutrons based on a tandem accelerator with vacuum insulation and a lithium target for the development of boron neutron capture therapy, a promising method for treating malignant tumors. To measure the "boron" dose due to the boron-lithium reaction, a small-sized detector has been developed. It consists of two polystyrene scintillators, one of which is enriched with boron. Using the detector, the spatial distribution of boron dose and dose of gamma radiation in a 330x330x315 mm water phantom was measured and the results obtained were compared with the results of numerical simulation of the absorbed dose components in such a tissue-equivalent phantom. It is shown that the results obtained are in good agreement with the calculated ones. It was found that the use of a 72 mm Plexiglas moderator provides an acceptable quality of the neutron beam for in vitro and in vivo studies, namely: 1 mA 2.05 MeV proton beam on a lithium target provides a dose rate of 30 Gy-Eq/h in cells containing boron at a concentration of 40 ppm, and 6 Gy-Eq/h in cells without boron. The developed technique for on-line measurement of boron dose and dose of gamma radiation makes it possible to carry out a similar verification of a neutron beam prepared for clinical trials of BNCT after placing a neutron beam shaping assembly with a magnesium fluoride moderator in a bunker adjacent to the accelerator., Proceedings of the 27th Russian Particle Accelerator Conference, RuPAC2021, Alushta, Russia

For the development of a promising method for the treatment of malignant tumors - boron neutron capture therapy - the accelerator-based epithermal neutron source has been proposed and created in the Budker Institute of Nuclear Physics. If the parameters of the proton beam change (energy and current of the beam, the parameters of the ion-optical system, the parameters of the ion source) - accordingly the conditions for the beam transportation change (its size, angular divergence, and position relative to the axis of the accelerator). For optimal conduction of the beam along the beam line, two-dimensional tomography of the beam can be used: using a cooled diaphragm with a diameter of several millimeters installed on a vacuum three-dimensional motion input and a Faraday cup, fast chord measurements are carried out, on the basis of which the beam profile is restored. The beam profile obtained by this way is somewhat different from the profile obtained by measuring the phase portrait of the beam using a wire scanner*. The advantage of this method is a relatively short time to restore the profile, depending on the diameter of the cooled diaphragm., Proceedings of the 27th Russian Particle Accelerator Conference, RuPAC2021, Alushta, Russia

A vacuum-insulated tandem accelerator was used to observe in situ blistering during 2-MeV proton irradiation of metallic samples to a fluence of up to 6.7 10²⁰ cm². Samples consisting of copper of different purity, tantalum, and tantalum-copper compounds were placed on the proton beam path and forced to cool. The surface state of the samples was observed using a CCD camera with a remote microscope. Thermistors, a pyrometer, and an infrared camera were applied to measure the temperature of the samples during irradiation. After irradiation, the samples were analyzed on an X-ray diffractometer, laser and electron microscopes. The present study describes the experiment, presents the results obtained and notes their relevance and significance in the development of a lithium target for an accelerator-based neutron source, for use in boron neutron capture therapy of cancer., Proceedings of the 9th Int. Particle Accelerator Conf., IPAC2018, Vancouver, BC, Canada

A source of epithermal neutrons based on a vacuum-insulated tandem accelerator and a lithium target is developed for the technique of boron neutron capture therapy. A stationary proton beam of 2 MeV with a current of up to 5 mA was obtained in the accelerator. Neutron generation was performed and the flux and neutron spectrum were experimentally measured. A Beam Shaping Assembly was developed and manufactured, which makes it possible to form a therapeutic beam of neutrons to the greatest extent satisfying the requirements of BNCT. It was established that neutron irradiation of tumor cells of human glioma U251 and human glioblastoma T98G, previously incubated in a medium with boron, led to a significant suppression of their viability. Irradiation of mice with grafted human glioblastoma tumor led to their complete cure. In order to increase the beam parameters, the facility was equipped with a wire scanner OWS-30 (D-Pace, Canada; under the license of TRIUMF), a non-contact current sensor NPTC (Bergos, France), a FLIR T650SC infrared camera, an Optris CT Laser 3ML SF pyrometer (Optris, GmbH, Germany), cooled diaphragms with thermistors, telescopic beam receivers with thermoresistors, a new bushing insulator. Two new sources of negative hydrogen ions with a high current are being prepared, one of them is surface-plasma, the other is voluminous. The investigations established the effect of space charge and spherical aberration of lens on the ion beam transport, the dependence of the heating of the diaphragms of the electrodes and the size of the proton beam on the current of the injected beam of negative hydrogen ions and the pressure of the residual gas in the transport channel. The report describes the modernization of the accelerator, discusses the results of research, declares plans., Proceedings of the 9th Int. Particle Accelerator Conf., IPAC2018, Vancouver, BC, Canada

In the BINP SB RAS was proposed and created a source of epithermal neutrons for BNCT. The proton beam is obtained on a tandem accelerator with vacuum insulation. Sectionalized demountable feed through insulator is an integral part of the accelerator. Voltage from the high voltage source is distributed to the electrodes via resistive divider. Because of the small amount of current (hundreds of microamperes) flowing through the divider, dark currents that occur in the accelerating gaps, can significantly affect the uniform distribution of the potential along the accelerating channel, and, consequently, on the beam transportation. Therefore there is a need to change the design of the feed through insulator which will allow to set potentials at the electrodes directly from the high voltage rectifier sections. To study the feasibility of such changes has been designed and built an experimental stand, in which a single insulator with double height subjected to the same conditions as in accelerator. On the experimental stand was studied electrical strength of ceramic and polycarbonate insulators with a different shape of the surface. The paper presents the results of experimental studies of insulators. Their application will get rid of the voltage divider inside the feed through insulator and realize the scheme which allows to set potential on the electrode gaps directly from the rectifier section. This will increase the operating voltage of the accelerator and its reliability., Proceedings of the 25th Russian Particle Accelerator Conf., RuPAC2016, St. Petersburg, Russia

In The Budker Institute of Nuclear Physics the accelerator-based source of epithermal neutrons was invented and now operates to be used in the boron neutron capture therapy. Neutrons on the facility are generated during the threshold reaction 7Li(p, n)7Be which occurs when the proton beam is thrown on the lithium target. To control the neutron output it is necessary to monitor the parameters of the accelerated proton beam. The spatial distribution of the accelerated proton beam was measured exactly on the lithium target. Due to the interaction of protons and lithium there is an accumulation of a radioactive isotope of beryllium takes place. After experiments about neutrons generation it seems possible to track an area of beryllium storage and then restore the proton beam profile. The monitoring of gamma-quants with the energy of 0,477 MeV arising during the beryllium decay was carried out via the gamma-spectrometric complex. The main part of this complex is NaI-scintillation detector, which was pre-calibrated with energy. As a result of such kind of diagnostic the profile of the beam, its shape and characteristic size were determined and the results are depicted in this paper. Afterwards it could be used for an estimation of the total neutrons flux, its quantity, also to assess the target state and restore the proton beam profile., Proceedings of the 25th Russian Particle Accelerator Conf., RuPAC2016, St. Petersburg, Russia

In BINP the neutron source for BNCT based on proton accelerator was designed and built. It is necessary for the therapy to ensure a stable proton beam current of not less than 3 mA with energy 2 MeV. During the injection of negative hydrogen ion beam into the accelerator the unwanted charged particles are produced, affecting the stability of beam parameters. The article describes meth-ods of suppression of undesirable charged particles and the results of experiments., Proceedings of the 25th Russian Particle Accelerator Conf., RuPAC2016, St. Petersburg, Russia

In The Budker Institute of Nuclear Physics the accelerator-based source of epithermal neutrons was invented and now operates to be used in the boron neutron capture therapy. For several reasons the real beam flow in the facility differs from the calculated one. To take into account this distinction it is necessary to provide continuous monitoring of the beam parameters. In order to optimize the facility operation the beam should be followed not only during the formation but also while an acceleration takes place and the proton beam is thrown on the lithium target as the proton current and energy influence on the neutron output. In this way it seems to be a significant issue to measure the current, profile and also the position of the ion beam in a low-energy part of the accelerator. This work represents the results of experiments with the D-Pace WS-30 Wire Scanner Probe, which was installed in the low-energy part of the accelerator. The experiments were carried out under various conditions to vary the position and focusing control via the system of magnetic correcting elements. To correctly interpret experimental data it was necessary to take into account physical phenomena which occur during an experiment. In this way the effects which take place when the probe interacts with the beam were thoroughly considered. The obtained results allowed to restore the ion beam profile, define its size and position., Proceedings of the 25th Russian Particle Accelerator Conf., RuPAC2016, St. Petersburg, Russia

A source of epithermal neutrons based on a tandem accelerator with vacuum insulation for Boron Neutron Capture Therapy of malignant tumors was proposed and constructed. Stationary proton beam with 2 MeV energy, 1.6 mA current, 0.1% energy monochromaticity and 0.5% current stability was obtained*. The flow of charged particles accompanying the accelerated ion beam was detected and measured**. To suppress this concomitant flow cooled diaphragm, cryopump and the electrostatic ring were installed in the input of accelerator. The surface of the vacuum vessel was covered with netting to suppress secondary electron emission. These steps have reduced the flow of charged particles 25 % of the ion beam to 0.5 % and to increase the current proton beam 3 times - up to 4.5 mA. The paper presents the results of research and declares plans to use the accelerator for the BNCT., Proceedings of the 7th Int. Particle Accelerator Conf., IPAC2016, Busan, Korea

In BINP neutron source for boron neutron capture therapy of cancer based on the vacuum insulation tandem accelerator and lithium target for neutron generation was constructed. After optimization of the injection of negative hydrogen ions and modernization of the stripping target 1.6 mA 2 MeV proton beam was obtained. Improvements of the accelerator to suppress accompanying electron current were introduced, and after making changes to protection system of high voltage power supply a stable proton beam with a current of 4.5 mA was obtained. Analysis of the experimental results shows that the beam is accelerated without losses. Obtaining of proton beam with the current of more than 3 mA offers the prospects of using of accelerators for BNCT in cancer clinics., Proceedings of the 7th Int. Particle Accelerator Conf., IPAC2016, Busan, Korea

New type of charged particles accelerator, tandem accelerator with vacuum insulation, was proposed in BINP. The accelerator is characterized by fast acceleration of charged particles, long distance between ion beam and insulator (on which electrodes are mounted), big stored energy in the accelerating gaps and strong input electrostatic lens. High-voltage strength of vacuum gaps, dark currents, ion beam focusing, accelerating and stripping were investigated. Stationary proton beam with 2 MeV energy, 1.6 mA current has just been obtained. The beam is characterized by high energy monochromaticity – 0.1%, and high current stability – 0.5%. Here we report the results of these investigations and discuss the proposal for obtaining 2.5 MeV 3 mA proton beam. The accelerator is considered to be a part of epithermal neutron source for boron neutron capture therapy and monoenergetic neutron source for calibration of dark matter detector., Proceedings of the 6th Int. Particle Accelerator Conf., IPAC2015, Richmond, VA, USA

A promising method of treatment of many malignant tumors is the boron neutron capture therapy (BNCT)*. It provides a selective destruction of tumor cells by prior accumulation of a stable boron-10 isotope inside them and subsequent irradiation with epithermal neutrons. It is expected that accelerator based neutron sources will be created for the clinical practice. One such source could be an original source of epithermal neutrons**, created in BINP. To obtain proton beam a new type of particle accelerator is used - tandem accelerator with vacuum insulation. Generation of neutrons is carried out as a result of the threshold reaction 7Li(p, n)7Be. During 2015-2016 in the construction of tandem accelerator with vacuum insulation several changes were made. This allowed us to suppress the unwanted flow of charged particles in the accelerator, to improve its high-voltage stability, and to increase the proton beam current from 1.6 to 5 mA. Such current value is sufficient for BNCT. The report describes in detail the modernization of the accelerator, presents and discusses the results of experiments on obtaining the proton beam and the formation of neutron flux using lithium target, and declares our prospective plans. The obtained neutron beam meets the requirements of BNCT: the irradiation of cell cultures provides the destruction of cells with boron and preservation of cells without boron. Irradiation of immunodeficient mice with grafted glioblastoma results in their recovery., Proceedings of the 25th Russian Particle Accelerator Conf., RuPAC2016, St. Petersburg, Russia