Budker INP & NSU, Novosibirsk, Russia
NSU, Novosibirsk, Russia
BINP SB RAS, Novosibirsk, Russia
BINP & NSTU, Novosibirsk, 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.
BINP SB RAS, Novosibirsk, Russia
Epithermal neutron source based on an electrostatic tandem accelerator of a new type - Vacuum Insulation Tandem Accelerator, and lithium neutron target has been proposed and developed at BINP* for Boron Neutron Capture Therapy** - promising method for treatment of tumors. 2 MeV proton beam was obtained in the accelerator, the neutron generation carried out with bombardment of a lithium target by protons, successful experiments on irradiation of cell cultures incubated in boron medium have been carried out, human glioblastoma grafted mice were cured. It is necessary to increase proton energy from 2 to 2.3 MeV to form a neutron beam suitable for the treatment of deep-seated tumors. It is necessary to provide the high-voltage strength of the accelerator at the potential of 1.2 MV in order to suppress dark currents to an acceptably small value. Two upgrades to obtain the required potential were consistently implemented. At first, the glass rings of the feedthrough insulator were replaced by ceramic ones doubled in height which made it possible to refuse placing the resistive divider inside. Then the smooth ceramic rings were replaced by the new ceramic rings with a ribbed outer surface. Modernization made it possible to obtain the required voltage of 1.15 MV and the proton beam current of 9 mA in the accelerator without breakdowns. The report describes in detail the modernizations carried out, presents the results of the studies, and declares the research plans.
* S. Taskaev. Phys. Part. Nucl. 46 (2015) 956-990. doi: 10.1134/S1063779615060064
** Neutron Capture Therapy: Principles and Applications. Eds.: W. Sauerwein et al. Springer, 2012.
BINP SB RAS, Novosibirsk, Russia
NSU, Novosibirsk, 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.
Budker INP & NSU, Novosibirsk, Russia
BINP SB RAS, Novosibirsk, Russia
NSU, Novosibirsk, Russia
An accelerator-based source of epithermal neutrons was proposed and created at the Budker Institute of Nuclear Physics. It consists of a vacuum-insulated tandem accelerator for producing a proton beam and a lithium target for generating neutrons as a result of the 7Li(p, n)7Be threshold reaction. With the use of a video camera and a spectrometer, the luminescence of lithium was registered when the lithium target was irradiated with protons. The recorded emission line 610.3 ± 0.5 nm corresponds to the electronic transition in the lithium atom 1s23d -> 1s22p, and the 670.7 ± 1 nm line corresponds to the 1s22p -> 1s22s transition. Based on the results of the study, the visual diagnostics for operational monitoring of the position and the size of the proton beam on the surface of a lithium target was developed and put into operation. The diagnostics can be applied in the neutron generation mode. The possibility of detecting luminescence made it possible to ensure the reliability of measuring the current of the argon ion beam accompanying the proton beam. When studying the blistering of a metal upon implantation of protons with an energy of 2 MeV, luminescence could lead to an overestimation of the surface temperature measured by a thermal imager.
BINP SB RAS, Novosibirsk, Russia
Budker INP & NSU, Novosibirsk, Russia
BINP, Novosibirsk, 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*.
* M. Bikchurina, et al 2D tomography of the proton beam in the vacuum-insulated tandem accelerator. These proceedings.
BINP SB RAS, Novosibirsk, Russia
Budker INP & NSU, Novosibirsk, Russia
NSU, Novosibirsk, Russia
Epithermal neutron source based on an electrostatic tandem accelerator of a new type - Vacuum Insulation Tandem Accelerator, and lithium neutron target has been proposed and developed at Budker Institute of Nuclear Physics for Boron Neutron Capture Therapy - promising method for treatment of tumors and for other applications. The paper proposes and implements a flexible and customizable method of operational data processing, allowing researchers to obtain and analyze information directly in the experiment without the need for post-processing data. Its use accelerates the process of obtaining informative data during experimental research and automates the analysis process. Also proposed and implemented a process of automatic distributed journaling of the results of the experiment. As a result of the implementation of the proposed tools increased the productivity of the analysis of experimental data and the detailing of the experimental journal. The developed and implemented system of real-time data processing has shown its effectiveness and has become an integral part of the control system, data collection and data storage of the epithermal neutron source.
BINP SB RAS, Novosibirsk, Russia
Budker INP & NSU, Novosibirsk, Russia
NSU, Novosibirsk, Russia
Budker Institute of Nuclear Physics, Novosibirsk, Russia
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.
