Aaron Magner Grayson Rich Phil Barbeau The 7 Li(p,n) Reaction Used for a monochromatic, tunable neutron source Neutrons used for calibration of new low-threshold detectors for neutrino and dark matter experiments (from Lee) Focus: Proton Beam and Target Health Use the tandem accelerator at TUNL as energetic proton source Determine proton flux at target; this is related to the rate of neutron production Neutron production can be influenced by contamination of the target (pump oil, for example) The Target Holder Determine composition of target (consider them as surface impurities on the Al backing) via proton back-scattering Know scattering elements by kinematics The Target Holder Determine composition of target (consider them as surface impurities on the Al backing) via proton back-scattering Know scattering elements by kinematics; see Backscattering Spectrometry, Chu. The Runs: Pileup Evident in runs with higher target current (hundreds of nanoamps) Reduce with baffles? The Runs: Pileup Evident in runs with higher target current (hundreds of nanoamps) Reduce with baffles? The Spectra Ratios of positions are appropriate for Li, F, and Al. Other contaminants? Possibly Be, B, N, and O. Be B N O Future Work Calibrate channels to energy Add baffles to reduce protons scattering from wall before reaching detector Cool the detector Put LiF on thin C substrate, separated from Al, to reduce deep scatters LiF on C Al References Chu, Wei-Kan. Backscattering Spectrometry Academic Press, Inc: San Diego, California Lee, Zhou, Thick target neutron yields for the 7Li(p,n)Be reaction near threshold, Nucl. Instr. and Meth. B 152, 1-11 (1999).