Upgrading the Lithium Fluoride Target Holder for Quenching Factor Studies

Aaron MagnerGrayson RichPhil Barbeau

The 7Li(p,n) ReactionUsed 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 HealthUse the tandem accelerator at TUNL as

energetic proton sourceDetermine proton flux at target; this is

related to the rate of neutron productionNeutron 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 HolderDetermine 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.

BeB

NO

Future WorkCalibrate channels to energyAdd baffles to reduce protons scattering from

wall before reaching detectorCool the detectorPut LiF on thin C substrate, separated from

Al, to reduce deep scatters

LiF on C Al

References

Chu, Wei-Kan. Backscattering Spectrometry. 1978. 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).