2012 DNP Meeting Abstracts
In Situ Calibration for Proton Particle Telescope
Stephen Padalino, Danae Polsin, Megan Russ, Michael Krieger, Mollie Bienstock, Drew Ellison, Angela Simone, Collin Stillman; SUNY Geneseo
Mark Yuly, Keith Mann, Tyler Reynolds; Houghton College
Craig Sangster; Laboratory for Laser Energetics
Neutrons produced via the 3H(2H,n)4He reaction at the Ohio University Accelerator Lab were used to activate a graphite sample via the 12C(n,2n)11C reaction in an attempt to measure the (n,2n) reaction cross section. Before striking the graphite, the neutrons struck a thin polyethylene foil and elastically scattered protons in to a surface barrier detector telescope. The recoiling protons were used to determine the energy and number of neutrons which struck the 12C activation sample. To verify that the particle telescope’s predicted response function for 15 to 27 MeV protons was correct a calibration of the detector telescope was performed in air on the SUNY Geneseo tandem Pelletron accelerator. High energy protons were created via the 2H(3He, p)4He reaction by bombarding a deuterated polyethylene target with 4.5 MeV 3He ions. The high-energy protons then pass through a Kapton window from vacuum into air where they were detected by the particle telescope. The dependence of the detector response on various proton energies was then investigated for various detector geometries. This data was extremely useful when performing the graphite activation experiment at the Ohio University accelerator lab.
*Funded in part by a grant from the DOE through the Laboratory for Laser Energetics
Cross Section of the (n, 2n) Reaction in 12C in the Energy Interval 20-30 MeV
Stephen Padalino, Danae Polsin, Megan Russ, Michael Krieger, Mollie Bienstock, Drew Ellison, Angela Simone, Collin Stillman; SUNY Geneseo
Mark Yuly, Keith Mann, Tyler Reynolds; Houghton College
Craig Sangster; Laboratory for Laser Energetics
The behavior of the (n, 2n) reaction in 12C and other light nuclei is known with much less certainty than for heavy nuclei. The published cross section data for the 12C(n, 2n)11C reaction is bifurcated in the energy range of 20-30 MeV. An experiment to measure the 12C(n, 2n)11C cross section for these neutron energies has been performed using the Ohio University Tandem Accelerator. Deuterons from the accelerator struck a tritium foil releasing neutrons via the T(d, n)4He reaction. Deuteron bombarding energies between 3.3-8.7 MeV resulted in neutrons with energies between 20-26 MeV. The geometry of the experiment was chosen so that the incident neutron energy would not vary by more than 0.5 MeV across the graphite target. After neutron bombardment, the decay of the 11C nuclei by positron emission was measured with an array of NaI detectors to determine the activity of the carbon sample. The neutron fluence through the carbon was measured using a particle telescope to detect protons from the 1H(n, p) reaction in a polyethylene target, allowing the absolute cross section for the 12C(n, 2n)11C reaction to be determined.
*Funded in part by a grant from the DOE through the Laboratory for Laser Energetics
Coincidence Efficiency Measurement Using 11B(p,n)11C
Stephen Padalino, Danae Polsin, Megan Russ, Michael Krieger, Mollie Bienstock, Drew Ellison, Angela Simone, Collin Stillman; SUNY Geneseo
Mark Yuly, Keith Mann, Tyler Reynolds; Houghton College
Craig Sangster; Laboratory for Laser Energetics
An attempt to measure the 12C(n,2n)11C cross section for high energy neutrons in the range of 20-30 MeV was conducted using Ohio University’s accelerator facility as a fast neutron source. The neutrons were incident on a graphite target and the ?+ decay of the activated carbon-11 nuclei were observed in an on-axis gamma ray detector pair. To predetermine the efficiency of this gamma ray detector system, a boron-11 activation experiment was performed. Using SUNY Geneseo’s 1.7 MV tandem pelletron accelerator, 3.1 MeV protons were incident upon the 11B foil inducing the 11B(p,n)11C reaction to occur at a high rate of activation. The 11C decays via ?+ emission, then upon annihilation with an electron creates characteristic 511-511 keV photon pairs which were counted using coincidence methods. Since the 11B(p,n) cross section is well defined, a calculation was performed to determine the expected number of activations and later compared to the total number of decays observed in the counting system.
*Funded in part by a grant from the DOE through the Laboratory for Laser Energetics
Design and Characterization of a Collimated Neutron Beam User Facility at SUNY Geneseo
Stephen Padalino, Michael Krieger, Megan Russ, Danae Polsin, Mollie Bienstock, Drew Ellison, Angela Simone; SUNY Geneseo
The Collimated Neutron Beam (CNB) Facility at SUNY Geneseo provides users an opportunity to perform neutron experiments that require a low neutron background. Neutrons with energies up to 10 MeV are produced by a Plutonium-Beryllium (Pu-Be) source and are collimated to form a well characterized beam. A six foot high, 18 inch thick shielding wall made of water-bricks was built to reduce neutron background in the target area. Neutron and gamma radiation were extensively mapped throughout the facility using a calibrated Bonner sphere, Geiger counter, plastic scintillator and an HPGe detector. Potential uses for the CNB include neutron activation, time-of-flight, attenuation and neutron detector calibration experiments. A detailed description and layout of the facility will be displayed on the poster.
*Funded in part by a grant from the DOE through the Laboratory for Laser Energetics