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arXiv · 2001.03432

A modular apparatus for use in high-precision measurements of parity violation in polarized eV neutron transmission`

D. C. Schaper·C. Auton·L. Barrón-Palos·M. Borrego·A. Chavez·L. Cole·C. B. Crawford·J. Curole·H. Dhahri·K. A. Dickerson·J. Doskow·W. Fox·M. H. Gervais·B. M. Goodson·K. Knickerbocker·C. Jiang·P. M. King·H. Lu·M. Mocko·D. Olivera-Velarde·J. G. Otero Munoz·S. I. Penttilä·A. Pérez-Martín·W. M. Snow·K. Steffen·J. Vanderwerp·G. Visser
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Abstract

We describe a modular apparatus for use in parity-violation measurements in epithermal neutron-nucleus resonances with high instantaneous neutron fluxes at the Manuel Lujan Jr.\ Neutron Scattering Center at Los Alamos National Laboratory. This apparatus is designed to conduct high-precision measurements of the parity-odd transmission asymmetry of longitudinally polarized neutrons through targets containing nuclei with p-wave neutron-nucleus resonances in the 0.1-10 eV energy regime and to accommodate a future search for time reversal violation in polarized neutron transmission through polarized nuclear targets. The apparatus consists of an adjustable neutron and gamma collimation system, a \(^3\)He-$^{4}$He ion chamber neutron flux monitor, two identical cryostats for target cooling, an adiabatic eV-neutron spin flipper, a near-unit efficiency \(^6\)Li-\(^{7}\)Li scintillation detector operated in current mode, a flexible CAEN data acquisition system, and a neutron spin filter based on spin-exchange optical pumping of $^{3}$He gas. We describe the features of the apparatus design devoted to the suppression of systematic errors in parity-odd asymmetry measurements. We describe the configuration of the apparatus used to conduct a precision measurement of parity violation at the 0.7 eV p-wave resonance in $^{139}$La which employs two identical $^{139}$La targets, one to polarize the beam on the p-wave resonance using the weak interaction and one to analyze the polarization.

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D. C. Schaper, C. Auton, L. Barrón-Palos, M. Borrego, A. Chavez, L. Cole, C. B. Crawford, J. Curole, H. Dhahri, K. A. Dickerson, J. Doskow, W. Fox, M. H. Gervais, B. M. Goodson, K. Knickerbocker, C. Jiang, P. M. King, H. Lu, M. Mocko, D. Olivera-Velarde, J. G. Otero Munoz, S. I. Penttilä, A. Pérez-Martín, W. M. Snow, K. Steffen, J. Vanderwerp, G. Visser. 2020-01-08. A modular apparatus for use in high-precision measurements of parity violation in polarized eV neutron transmission`. https://doi.org/10.1016/j.nima.2020.163961

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