Slow neutrons from a 24 mev betatron
Bramblett, Richard Lee
Bonner, T. W.
Master of Arts
Associated with any particle accelerator are always background radiations resulting from interactions of the energized particles with the material of the accelerator. In the case of a betatron, where x-radiation is produced by bremsstrahlung in a target, there is a significant background of neutrons from the interaction of the x-rays with the lead of the collimator. The measurement of this background neutron flux is important in radiation therapy because neutrons have different biological effects from x-rays. Furthermore, the background neutrons are of interest to the physicist for the insight they give to the photo-neutron process, and for the techniques that must be developed to measure neutrons in the intense x-ray flux surrounding the betatron. In order to evaluate the biological effect of the neutrons relative to that of the x-radiation from the betatron, the radiation therapist needs to know the number versus energy distribution of the neutrons. This was the problem presented by M. D. Anderson Hospital and Tumor Institute: What is the number versus energy distribution of background neutrons from the M. D. Anderson 24 million volt betatron? The problem divides practically into two parts; slow neutrons, with energies in the range from zero to a few electron volts, and fast neutrons, with energies in the kilovolt range and higher. This work will consider only the former part of the problem: Slow Neutrons from a 24 Million Volt Betatron.