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
Budker INP & NSU, Novosibirsk, 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.
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
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.
