DNP Meeting Abstracts

The Associated Particle Method

Sarah Thompson and Brook Schartz
Department of Physics and Astronomy
The State University of New York at Geneseo
Dr. Kurt Fletcher and Dr. Stephen Padalino

The Laboratory for Laser Energetics (LLE) at the University of Rochester is investigating laser induced Inertial Confinement Fusion. In order to understand the dynamics of the fusion plasma process, LLE uses calibrated neutron detectors to determine the neutron yield produced by DD and DT thermonuclear reactions. Geneseo’s Nuclear Structure Laboratory (GNSL), has undertaken the calibration of these detectors for LLE. By using the associated particle method, the energy response and the efficiency of the detectors has been determined. The associated particle method uses the nuclear reaction d(d,n)3He @ 300 and 500 keV to produce 3He particles and neutrons which are measured in coincidence. The d(d,n)3He reaction was created using GNSL’s two million volt Van de Graaff accelerator. By comparing the number coincident counts detected between the neutron detector and the counts detected by the charged particle detector, the efficiency of the neutron detectors was determined. Since the energy of the neutrons produced by d(d,n)3He is strictly dictated by energy and momentum conservation laws, the response of the neutron detector was also determined by investigating.

*Funded in part by the Department of Energy

ALUMINUM ACTIVATION TO DETERMINE NEUTRON YIELD OF D-T FUSION REACTIONS

Joel, Nyquist and Heather Olliver
Department of Physics and Astronomy
The State University of New York at Geneseo
Dr. Kurt Fletcher and Dr. Stephen Padalino
Laboratory for Laser Energetics, University of Rochester
Dr.Vladimir Glebov and Nancy Rogers

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

Carbon Activation using High Energy Neutrons

OLLIVER, Heather and NYQUIST, Joel
Department of Physics and Astronomy
The State University of New York at Geneseo
Dr. Stephen Padalino
Scott Lassell, Cornell University, Ward Reactor Laboratory
Radha Bahukutumbi, Laboratory for Laser Energetics, University of Rochester

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. The Ariel density of an inertial confinement fusion (ICF) reaction can be determined by calculating the ratio of the tertiary neutron yield to the primary neutron yield. During an ICF reaction, 14.1 MeV neutrons emitted from the T(d,n) fusion reaction strike fuel deuterons causing them to accelerate. These deuterons then collide with tritium fuel to produce tertiary T(d,n) reactions that produce high energy neutrons in the range of 18 to 30 MeV. A pure carbon sample is placed near the reaction where it becomes activated through the 12C(n,2n)11C reaction which has a high neutron threshold and can not be activated by the primary neutrons. The 11C consequently beta decays by emitting positrons. Once activated, the sample is removed from the reaction area. High Purity Germanium Detectors or NaI detectors can then count, in coincidence, the back to back 511 keV gamma rays emitted from the positron annihilation. The number of gamma rays counted is directly related to the tertiary neutron yield of the fusion reaction. The chief concern of using this method arises from contamination of the graphite with materials that will be activated by the primary neutrons, such as copper. These contaminants have been investigated through the use of trace elemental analysis methods at the Cornell Research reactor.

*Funded in part by the Department of Energy

CR-39 IN A CHARGED PARTICLE SPECTROMETER AS A DIAGNOSTIC FOR INERTIAL CONFINEMENT FUSION

Brook Schwartz and Sarah THOMPSON
Department of Physics and Astronomy
The State University of New York at Geneseo
Dr. Stephen Padalino
Jason Law, Laboratory for Laser Energetics, University of Rochester
Dr. Richard Petrasso, Massachusetts Institute of Technology

The purpose of the Laboratory for Laser Energetics at the University of Rochester is to study Laser driven inertial confinement fusion reactions. One of the many nuclear diagnostics used to examine these reactions is the charged particle spectrometer. The magnetic spectrometer is designed to detect the mass and energy of charged particles produced by either d-d or d-t reactions during the 1 nano-second burn time. As the charged reaction products enter the spectrometer they are bent by its magnetic field through various paths and thus directed toward and detected by an array of CR-39 track emulsions. Upon impact with the emulsion, the particles produce holes in the CR-39. The hole diameter and depth is directly related to the mass and energy of the incident particle. The 2 MV Van de Graaff accelerator at SUNY Geneseo was used to calibrate the track diameter and hole depth to the corresponding mass and energy. Protons of known energy, from 400 to 1000 KeV, were elastically scattered off gold foil such that they scattered on to CR-39 to calibrate proton tracks. Similarly, using the radioactive isotope AM241, 5.44 MeV alpha particles were directed toward the CR-39 and the resulting hole depth and diameter were used to calibrate alpha tracks.

*Funded in part by the Department of Energy