Neutron Energy Distribution of an AmBe Source at the MGH Proton Center

At Suffolk University, the Neutron Research Project has been investigating the neutron energy distribution of an Americium-Beryllium (AmBe) source located at Massachusetts General Hospital (MGH). The energy distribution of AmBe sources varies and the distribution of the one at MGH is unknown. Using an array of commercially available energy threshold bubble detectors, we have constructed a six window energy histogram of the activity ranging from 0 to 20 MeV. To mitigate backscattering that causes artificially high bubble counts, we used a rectangular array of detectors on posts with the source on a  polyethylene stack. Additionally, to eliminate non-physical negative activities due to statistical errors, we developed a program to solve the six-coupled energy absorption equations by minimizing the error squared from predicted and measured bubble counts. The end result is activity, with errors, of the AmBe source in the six different energy regions. Knowing this we will be able to pursue the determination of energy dependent neutron attenuation coefficients of different materials.