Joel Nyquist, SUNY Geneseo

Title: Aluminum Activation to Determine Neutron Yield

Authors: J. Nyquist, H. Olliver, K. Fletcher, S. Padalino (SUNY Geneseo); V. Glebov, N. Rogers (Laboratory for Laser Energetics, University of Rochester)

Abstract: The Laboratory for Laser Energetics at the University of Rochester has been conducting experiments using laser induced nuclear fusion as a possible alternative energy source. An important metric used in this research is the measure of the neutron yield. The absolute neutron yield of an inertially confined fusion reaction can be found using aluminum activation.  An aluminum sample is placed near the target where 14.1 MeV neutrons emitted from the T(d,n) fusion reaction cause the aluminum to become activated and consequently to emit gamma rays. Neutron activation of aluminum occurs by several neutron reactions. Four such reactions are described: 27Al + n = 28Al, 27Al(n,a )24Na, 27Al(n,2n)26Al and 27Al(n,p)27Mg. The radioactive nuclei 28Al, 24Na,  and 27Mg, which are produced via the 27Al + n = 28Al, 27Al(n,a )24Na and 27Al(n,p)27Mg neutron reactions, beta decay to excited states of 28Si, 24Mg and 27Al respectively. These excited states then emit gamma rays as the nuclei de-excite to their respective ground states. Once activated, the sample is removed from the reaction area where a High Purity Germanium Detector can then count the gamma rays emitted by the sample.  The number of gamma rays counted is directly related to the neutron yield of the fusion reaction.  The results of this method are compared to other neutron diagnostic methods in an overall effort to determine the efficiency of each fusion reaction.  

*Funded in part by the Department of Energy