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Browsing Physics: Posters by Author "Desmitt, Holly"
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- ItemAnalysis of a Measurement of 12C(n,2n)11C Cross Sections(Houghton College, 2013-11-11) Hartshaw, Garrett; Love, Ian; Yuly, Mark; Padalino, Stephen; Russ, Megan; Bienstock, Mollie; Simone, Angela; Ellison, Drew; Desmitt, Holly; Massey, Thomas; Sangster, CraigIn inertial confinement fusion (ICF), nuclear fusion reactions are initiated by bombarding a small fuel pellet with high power lasers. One ICF diagnostic tool involves placing graphite discs within the reaction chamber to determine the number of high-energy neutrons. This diagnostic requires accurate 12C(n,2n)11C cross sections, which have not been previously well measured. An experiment to measure this cross section was conducted at Ohio University, in which DT neutrons irradiated polyethylene and graphite targets. The neutron flux was determined by counting recoil protons from the polyethylene in a silicon dE-E detector telescope. Preliminary cross sections were calculated using the incident neutron flux and the number of 11C nuclei in the graphite and polyethylene targets determined by counting, in a separate counting station, the gamma rays resulting from the positron decay of 11C. This poster will present the data analysis techniques used to determine theses cross sections and the calculation of the corrections needed to account for the detector and target geometry. Funded in part by a LLE contract through the DOE.55th Annual Meeting of the APS Division of Plasma Physics, Denver, Colorado, November 11-15, 2013; Omega Laser Facility Users Group Workshop, Laboratory for Laser Energetics, Rochester, NY, April 23-25, 2014.
- ItemCoincidence Efficiency of Sodium Iodide Detectors for Positron Annihilation(Houghton College, 2014-10-27) Eckert, Thomas; Vincett, Laurel; Yuly, Mark; Stephen Padalino,; Russ, Megan; Bienstock, Mollie; Simone, Angela; Ellison, Drew; Desmitt, Holly; Sangster, Craig; Regan, SeanOne possible diagnostic technique for characterizing inertial confinement fusion reactions involves tertiary neutron activation of 12C via the 12C(n,2n)11C reaction. Because the cross section for this reaction is not well measured in the energy range of interest, a new measurement was recently made at Ohio University. Part of this experiment involves counting the positron annihilation 511 keV gamma rays from the 11C decay using two sodium iodide detectors in coincidence. A new technique has been developed to measure the coincidence efficiency by detecting the positron prior to its annihilation, and requiring that the 1275 keV gamma ray also emitted by the 22Na be in the full-peak in another NaI(Tl) detector. Measurements and simulation results for the absolute coincidence full-peak efficiencies are presented.56th Annual Meeting of the APS Division of Plasma Physics, New Orleans, Lousiana, October 27-31, 2014; Penn-York Undergraduate Research Association Conference, Houghton College, Houghton, NY 14744. Nov. 1, 2104; XXXIV Annual Rochester Symposium for Physics Students, SUNY Oswego, Oswege, NY, April 11, 2015; Omega Laser User’s Group Meeting, Laboratory for Laser Energetics, Rochester, NY, April 22-24, 2015.
- ItemEfficiency Calibration for Measuring the 12C(n, 2n)11C Cross Section(Houghton College, 2015-11-16) Eckert, Thomas; Gula, August; Vincett, Laurel; Yuly, Mark; Padalino, Stephen; Russ, Megan; Bienstock, Mollie; Simone, Angela; Ellison, Drew; Desmitt, Holly; Fitzgerald, Ryan; Sangster, Craig; Regan, SeanOne possible inertial confinement fusion diagnostic involves tertiary neutron activation via the 12C(n, 2n)11C reaction. A recent experiment to measure this cross section involved coincidence counting annihilation gamma rays produced by the positron decay of 11C. This requires an accurate value for the full-peak coincidence efficiency of the NaI detector system. The GEANT 4 toolkit was used to develop a Monte-Carlo simulation of the detector system which can be used to calculate the required efficiencies. For validation, simulation predictions have been compared with the results of three experiments. In the first, full-peak coincidence positron annihilation efficiencies were measured for 22Na positrons that annihilate in a small plastic scintillator. In the second and third, NIST-calibrated 22Na and 68Ge sources were placed between copper and graphite disks. A comparison of calculated with measured efficiencies, as well as 12C(n, 2n)11C cross sections, are presented.57th Annual Meeting of the APS Division of Plasma Physics, Savannah, GA, Nov. 16-20, 2015; XXXV Annual Rochester Symposium for Physics Students, University of Rochester, Rochester, NY., April 2, 2016; Omega Laser User’s Group Meeting, Laboratory for Laser Energetics, Rochester, NY, April 27-29, 2016; 2015 APS Division of Plasma Physics Outstanding Undergraduate Poster Award.