Measuring the neutron spectrum of the accelerator-based source using the time-of-flight method

Abstract

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. Spe cific problems arising thereby and methods for solving them are described. The measured spectrum of neu trons in the reaction 7 Li(p, n) 7 Be at a proton energy of 1.915 MeV is presented and compared to the calcula tion. This spectrum is shown to comply with the requirements for the neutron beam used in neutron capture therapy.

Accelerator based epithermal neutron source

“…The number of bubbles formed in the BDT detector turned out to be 15-20 times higher than in the BD100R detector, in agreement with the calculated spectrum [141]. With a good level of details, the energy spectrum of neutrons was measured by the time of flight method [85] when generating short pulses of neutron radiation and neu tron detection by a remote detector (Saint Gobain Crystals) with lithium containing scintillator GS20. To create short bursts of neutrons, a new technical solution [142] based on the use of threshold character of the cross section of the 7 Li(p,n) 7 Be reaction was proposed and implemented.…”

“…According to this curve, the energy spread of protons is ±2 keV. In the second method, the long term stability of the proton beam energy was assessed by measuring the neutron spec trum with the help of time of flight technique: its value turned out to be better than ±5 keV [85]. The proton beam energy is measured using the resistive voltage divider of high voltage power supply.…”

Proton beam of 2 MeV 1.6 mA on a tandem accelerator with vacuum insulation

“…The energy spread of the protons defined using this curve was ± 2 keV. During measurement of the neutron spectrum using time-of-flight technique a longterm stability of the proton beam energy was also evaluated -better than ± 5 keV [16].…”