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
BINP SB RAS, 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. 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.
ITEP, Moscow, Russia
The interest in measuring spectrum of electron beams by the method of absorbing filters is due to its technical accessibility, compactness, efficiency and usability at various research facilities. The complexity of this method lies in severe ill-posedness of the inverse problem of reconstruction the spectrum from the beam absorption. The task of our work is the operational control of the spectrum of a beam with the maximum energy up to 300 keV. The current collector package consists of 16 insulated identical aluminum foils with the 1 mm gap between. The thickness range of the foils is 10 to 25 microns, depending on the maximum electron energy. The charge of the foils after passing the beam is measured by the ADC. The assembly geometry was calculated by the Monte Carlo method to determine the accumulation of charges on foils when monoenergetic beams are transmitted in the range from 10 to 300 keV with step increment of 10 keV. The inverse problem was solved by Tikhonov regularization. It turned out that a high-accuracy fitting of the input data and the transformation kernel by statistical distributions is the primary factor, which allows to reduce the regularization parameter to almost zero. The validity of the technique applied is confirmed by the fact that the spectrum obtained at the maximum electron energy of the beam of 250 keV is in satisfactory agreement with the spectrum measured on a magnetic spectrometer.