@article{swanson_heckel_bass_bass_dawkins_horton_luo_snow_walbridge_crawford_et al._2019, title={Experimental upper bound and theoretical expectations for parity-violating neutron spin rotation in He-4}, volume={100}, ISSN={["2469-9993"]}, DOI={10.1103/PhysRevC.100.015204}, abstractNote={Neutron spin rotation is expected from quark-quark weak interactions in the standard model, which induce weak interactions among nucleons that violate parity. We present the results from an experiment searching for the effect of parity violation via the spin rotation of polarized neutrons in a liquid 4He medium. The value for the neutron spin rotation angle per unit length in 4He, dϕ/dz=[+2.1±8.3(stat.)−0.2+2.9(sys.)]×10−7 rad/m, is consistent with zero. The result agrees with the best current theoretical estimates of the size of nucleon-nucleon weak amplitudes from other experiments and with the expectations from recent theoretical approaches to weak nucleon-nucleon interactions. In this paper we review the theoretical status of parity violation in the n→+ 4He system and discuss details of the data analysis leading to the quoted result. Analysis tools are presented that quantify systematic uncertainties in this measurement and that are expected to be essential for future measurements.}, number={1}, journal={PHYSICAL REVIEW C}, author={Swanson, H. E. and Heckel, B. R. and Bass, C. D. and Bass, T. D. and Dawkins, J. M. and Horton, J. C. and Luo, D. and Snow, W. M. and Walbridge, S. B. and Crawford, B. E. and et al.}, year={2019}, month={Jul} }
 @article{mumm_huber_bauder_abrams_deibel_huffer_huffman_schelhammer_janssens_jiang_et al._2016, title={High-sensitivity measurement of He-3-He-4 isotopic ratios for ultracold neutron experiments}, volume={93}, number={6}, journal={Physical Review C}, author={Mumm, H. P. and Huber, M. G. and Bauder, W. and Abrams, N. and Deibel, C. M. and Huffer, C. R. and Huffman, P. R. and Schelhammer, K. W. and Janssens, R. and Jiang, C. L. and et al.}, year={2016} }
 @article{coakley_dewey_huber_huffer_huffman_marley_mumm_o'shaughnessy_schelhammer_thompson_et al._2016, title={Survival analysis approach to account for non-exponential decay rate effects in lifetime experiments}, volume={813}, ISSN={["1872-9576"]}, url={https://doi.org/10.1016/j.nima.2015.12.064}, DOI={10.1016/j.nima.2015.12.064}, abstractNote={In a variety of neutron lifetime experiments, in addition to $\beta-$decay, neutrons can be lost by other mechanisms including wall losses. Failure to account for these other loss mechanisms produces systematic measurement error and associated systematic uncertainties in neutron lifetime measurements. In this work, we develop a physical model for neutron wall losses and construct a competing risks survival analysis model to account for losses due to the joint effect of $\beta-$decay losses, wall losses of marginally trapped neutrons, and an additional absorption mechanism. We determine the survival probability function associated with the wall loss mechanism by a Monte Carlo method. Based on a fit of the competing risks model to a subset of the NIST experimental data, we determine the mean lifetime of trapped neutrons to be approximately 700 s -- considerably less than the current best estimate of (880.1 $\pm$ 1.1) s promulgated by the Particle Data Group [1]. Currently, experimental studies are underway to determine if this discrepancy can be explained by neutron capture by ${}^3$He impurities in the trapping volume. Analysis of the full NIST data will be presented in a later publication.}, journal={NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT}, publisher={Elsevier BV}, author={Coakley, K. J. and Dewey, M. S. and Huber, M. G. and Huffer, C. R. and Huffman, P. R. and Marley, D. E. and Mumm, H. P. and O'Shaughnessy, C. M. and Schelhammer, K. W. and Thompson, A. K. and et al.}, year={2016}, month={Mar}, pages={84–95} }
 @article{snow_anderson_barron-palos_bass_bass_crawford_crawford_dawkins_esposito_fry_et al._2015, title={A slow neutron polarimeter for the measurement of parity-odd neutron rotary power}, volume={86}, number={5}, journal={Review of Scientific Instruments}, author={Snow, W. M. and Anderson, E. and Barron-Palos, L. and Bass, C. D. and Bass, T. D. and Crawford, B. E. and Crawford, C. and Dawkins, J. M. and Esposito, D. and Fry, J. and et al.}, year={2015} }
 @article{huffman_coakley_doyle_huffer_mumm_o'shaughnessy_schelhammer_seo_yang_2014, title={Design and performance of a cryogenic apparatus for magnetically trapping ultracold neutrons}, volume={64}, ISSN={["1879-2235"]}, DOI={10.1016/j.cryogenics.2014.09.008}, abstractNote={The cryogenic design and performance of an apparatus used to magnetically confine ultracold neutrons (UCN) is presented. The apparatus is part of an effort to measure the beta-decay lifetime of the free neutron and is comprised of a high-current superconducting magnetic trap that surrounds ∼21 l of isotopically pure 4He cooled to approximately 250 mK. A 0.89 nm neutron beam can enter the apparatus from one end of the magnetic trap and a light collection system allows visible light generated within the helium by decays to be transported to detectors at room temperature. Two cryocoolers are incorporated to reduce liquid helium consumption.}, journal={CRYOGENICS}, author={Huffman, P. R. and Coakley, K. J. and Doyle, J. M. and Huffer, C. R. and Mumm, H. P. and O'Shaughnessy, C. M. and Schelhammer, K. W. and Seo, P-N. and Yang, L.}, year={2014}, pages={40–50} }