# Bulletin of the American Physical Society

# 2020 Fall Meeting of the APS Division of Nuclear Physics

## Volume 65, Number 12

## Thursday–Sunday, October 29–November 1 2020; Time Zone: Central Time, USA

## Session SP: Mini-Symposium: Hadronic Weak Interactions III |
Hide Abstracts |

Chair: Danielle Schaper, UKY |

Sunday, November 1, 2020 10:30AM - 10:42AM |
SP.00001: Proposed Experiment to Measure the Parity-Odd Asymmetry in the 0.73 eV Neutron Resonance in Polarized $^{139}$La Gabriel Otero Munoz, William Snow The 0.7 eV p-wave resonance in $^{139}$La can amplify both parity-odd (P) and time-reversal odd (T) effects from mixing of s-wave and p-wave resonances [1], and a null test of T is possible for this observable [2]. To quantify potential sources of systematic errors and to fix the spectroscopic parameter $\kappa$ which determines the P-odd/T-odd measurement sensitivity, we propose to measure the P-odd correlation term $A$ from $\mathbf{k \cdot I}$ in the forward scattering amplitude, where $\mathbf{k}$ is the neutron momentum and $\mathbf{I}$ is the nuclear polarization. We present an experiment to measure $A$ using the neutron diffraction instrument POLI at the FRM research reactor, which views a hot graphite neutron moderator. The only previous experiment [3] measured $A =0.31 \pm 0.09$, which does not suffice to determine $\kappa$. We describe our experimental design and approach which can lower the error by an order of magnitude and determine $\kappa$. [1] V. P. Gudkov, Physics Reports 212, 77 (1992). [2] J. D. Bowman and V. P. Gudkov, Phys. Rev. C 90, 065503 (2014). [3] V. P. Alfimenkov et al, Phys. Atm. Nucl. 59, 1861 (1996). [Preview Abstract] |

Sunday, November 1, 2020 10:42AM - 10:54AM |
SP.00002: Characterization of p-wave resonances in $^{139}$La and $^{81}$Br for NOPTREX Kylie Dickerson, William Snow Few of the p-wave resonances under consideration for use in NOPTREX have quantified errors for the resonance energy and width. We describe a plan to measure the p-wave resonance energies in $^{139}$La and $^{81}$Br to about 0.1\% accuracy using a $^{10}$B current mode neutron detector array [1] on FP05 at LANSCE. We also present an analysis of preliminary data taken on $^{139}$La. This work is supported by NSF grant PHY-1913789. \newline [1] Y. F. Yen et al., Nucl. Inst. Meth. A 447, 476 (2000). [Preview Abstract] |

Sunday, November 1, 2020 10:54AM - 11:06AM |
SP.00003: Measurement of $\gamma$-ray Angular Distribution of n+$^{131}$Xe Reaction in 3.2 eV p-wave Resonance for T-Violation Search Experiment Clayton Auton The Neutron OPtics Time Reversal Experiment (NOPTREX) collaboration plans to conduct a sensitive search for time reversal invariance violation in polarized neutron transmission through polarized nuclei by taking advantage of the large amplification of symmetry-violating effects due to s-wave and p-wave mixing in heavy nuclei. The same mechanism responsible for the observed enhancements of P-violation is theoretically predicted to also enhance T-violation. The spin factor $\kappa (J)$ sets the relative size and sensitivity of these two effects. The angular distribution of the $^{131}$Xe(n,$\gamma$) capture reaction as a function incident neutron energy was measured using the ANNRI germanium detector array at J-PARC. From this $\gamma$-ray angular distribution one can extract the unmeasured $\kappa (J)$ needed to gauge the feasibility of a T-violation search in the $^{131}$Xe 3.2 eV p-wave resonance. This talk will discuss the ongoing experiment and analysis. [Preview Abstract] |

Sunday, November 1, 2020 11:06AM - 11:18AM |
SP.00004: Analysis of P- and T-violation effect in NOPTREX Experimental Scheme. Hejer Dhahri, Ivan Novikov, William Snow The Neutron Optics Parity and Time Reversal EXperiment (NOPTREX) will search for possible parity (P) and time (T) reversal invariance violating effects in propagation of polarized neutrons with polarized target. It can be realized by comparing the polarization of an initially unpolarized neutron beam (P) to the asymmetry of initially polarized neutron beam (A) in propagation through a polarized target. The difference between measured polarization and asymmetry would indicate the presence of PT-violating interaction [1]. The measurement can be realized by reversing the neutron polarizer and polarized target on a rotating turntable so the neutron polarizer acts as a neutron analyzer. This method can be free from final state effects [2]. In this talk, using techniques introduced in [3] and [4], we discuss energy dependence of PT-violating effect on a neutron energy, and the possible systematic uncertainties that can arise from various types of deviations from the idealized conditions. [1] P.K. Kabir, Phys. Rev. D, 25, 1985, p. 2013 [2] J. D. Bowman and V. P. Gudkov, Phys. Rev. C 90, 065503 (2014). [3] R. Golub, S.K. Lamoreaux, Phys Rev D, 50, 9, 1994. [4] V. Bunakov V. Gudkov, Z. Phys. A, v.308, 1982, p. 363; V. Bunakov Physics of Particles and Nuclei, v. 26, 2, 1995, pp.115-1 [Preview Abstract] |

Sunday, November 1, 2020 11:18AM - 11:30AM |
SP.00005: A Modular NaI(Tl) Detector Array for Parity- and Time Reversal-Odd Measurements for NOPTREX Jason Fry, Ivan Novikov The NOPTREX collaboration proposes to conduct a sensitive search for time reversal invariance violation (TRIV) in polarized neutron transmission through polarized nuclei, exploiting properties of low energy neutron-nucleus resonances which amplify TRIV. The same amplification mechanisms known to generate parity violation (PV) can also enhance TRIV effects. NOPTREX also plans to measure PV asymmetries in eV neutron-nucleus resonances to higher precision for input to TRIV parameters in key nuclei of interest, such as $^{139}$La and $^{131}$Xe, and in a broad search of heavy nuclei. We will discuss the ongoing efforts to develop and characterize a $^{10}$B + NaI(Tl) detector array to measure both PV in nuclei with higher precision and parameters of TRIV neutron resonances, and report on the results of MCNP simulations of the array performance. [Preview Abstract] |

Sunday, November 1, 2020 11:30AM - 11:42AM |
SP.00006: A First Measurement of the Spin-Dependent Neutron-Nucleus Forward Scattering Amplitudes in Polarized Neutron-Polarized $^{131}$Xe and $^{129}$Xe Nuclei Using Pseudomagnetic Precession Hao Lu Spin-dependent amplitudes in polarized neutron-polarized nucleus forward scattering can cause systematic errors in NOPTREX. We performed the first measurement of neutron pseudomagnetic precession\footnote{Zimmer, O., Ehlers, G., Farago, B. et al. A precise measurement of the spin-dependent neutron scattering length of 3He. EPJ direct 4, 1–28 (2002). https://doi.org/10.1007/s1010502a0001} in neutron transmission through polarized $^{131}$Xe and $^{129}$Xe with the J-NSE Neutron Spin Echo spectrometer at FRM II reactor facility in Germany\footnote{Heinz Maier-Leibnitz Zentrum. (2015). J-NSE: Neutron spin echo spectrometer. Journal of large-scale research facilities, 1, A11. http://dx.doi.org/10.17815/jlsrf-1-34}. We are also constructing an optical model for the incoherent scattering lengths in all nuclei using the extensive n-A resonance data from National Nuclear Data Center (NNDC). We will present the experimental setup of the polarized Xenon pseudomagnetic precession measurement, the result, and the theoretical calculation as applied to Xenon nuclei. [Preview Abstract] |

Sunday, November 1, 2020 11:42AM - 11:54AM |
SP.00007: Absolute magnetization calibration of polarized $^{131}$Xe for measurement of the $^{131}$Xe nuclear pseudomagnetism using neutron spin echo Earl Babcock We plan to investigate T violation in neutron interactions with heavy nuclei at a compound nuclear p-wave resonance by searching for a P-odd and T-odd term in the neutron forward scattering amplitude. $^{131}$Xe is a good candidate because its P-odd effects have already been measured to be sufficiently large. However, the pseudomagnetic precession of polarized neutrons, caused by the previously unmeasured neutron incoherent scattering length of the polarized $^{131}$Xe target, would be a large systematic error. Measurement of this incoherent neutron scattering length requires absolute polarimetry of $^{131}$Xe. Here neutrons provide us a method for NMR calibration using hyperpolarized $^3$He as the standard instead of the more typical thermally polarized $^1$H sample. Since the $^3$He polarization dependent neutron absorption cross section is accurately known, measurement of neutron absorption of the polarized $^3$He gives an absolute NMR calibration. The absolute $^{131}$Xe polarimetry/magnetization used to determine the neutron incoherent scattering length of $^{131}$Xe as measured from its pseudomagnetic precession observed in measurements on the JNSE instrument at the FRMII is discussed [1]. \par \noindent [1] Heinz Maier-Leibnitz Zentrum et al. (2015). JLSRF, 1, A11. [Preview Abstract] |

Sunday, November 1, 2020 11:54AM - 12:06PM |
SP.00008: Design of an adiabatic spin flipper for epithermal neutrons. Spin flip efficiency calculations Alberto Perez-Martin, Libertad Barron-Palos An adiabatic spin flipper (SF) was designed as a part of a neutron transmission experiment developed at LANSCE (Los Alamos Neutron Science Center) in order to study parity violation (PV) in resonances of compound nuclei accessible with epithermal neutrons. A similar setup will be used in a transmission experiment to study time reversal invariance violation (TRIV) in the same systems. The PV term in the zero-angle scattering amplitude for neutrons is highly dependent on the spin orientation relative to its momentum [1], so the spin has to be precisely manipulated. The shape of the ideal magnetic field was found and an arrangement of electric currents was designed to produce such a field. The theoretical efficiency of the spin flipper [2] and its dependence on the magnetic field intensity was calculated. The magnetic field amplitude resulting in high and stable efficiency was chosen. After having the magnetic field maps for the SF space region a spin transport simulation was carried out in order to determine a more realistic efficiency of the apparatus. \begin{thebibliography}{9} \bibitem{ref 1} J.D.Bowman, V.Gudkov, Phys. Rev. C 90, 065503 (2014) \bibitem{ref 2} J.D.Bowman, S.I.Penttila and W.B.Tippens, Nucl. Instrum. Methods A369, 195 (1996) \end{thebibliography} [Preview Abstract] |

Sunday, November 1, 2020 12:06PM - 12:18PM |
SP.00009: Analysis of P- and T-violation effects in Experiment with Polarized Neutron Propagation through Two Polarized Targets Ivan Novikov, William Snow, Lars Hebenstiel The NOPTREX collaboration is developing several experimental schemes to measure P- and T-violating effects in propagation of polarized neutron beam through a polarized target. As it was shown in [1], P- and T-violating effects are enhanced in a vicinity of a p-resonance by 5 -- 6 orders of magnitude. We analyze an experimental scheme with a polarized $^{\mathrm{139}}$La target split along the beam direction, polarized in opposite directions along the x-axis, with a magnetic field precession coil in between to precess the neutron polarization by 180$^{\mathrm{o}}$. Using technique introduced in [2], we analyze the peak value of the asymmetry and its dependence on neutron energy. To compare this separated-target experimental scheme to other possible ways to measure P- and T-violation proposed in [3], [4], we estimate relative error of the measured experimental effect and several systematic errors. \begin{enumerate} \item V. Bunakov V. Gudkov, Z. Phys. A, v.308, 1982, p. 363. \item R. Golub, S.K. Lamoreaux, Phys. Rev. D, 50, 9, 1994. \item V.R. Skoy, Phys. Rev. D, 53, 7, 1996 \item A.P. Serebrov, JETP Lett., 58, 14, 1993 \end{enumerate} [Preview Abstract] |

Sunday, November 1, 2020 12:18PM - 12:30PM |
SP.00010: One Step to Precision Measurement from Quantum Contextuality Test of Entangled Single Neutron Jiazhou Shen, Steve Kuhn, Eric Dees, Samuel McKay, Shufan Lu, Abu Ashik Md Irfan, David Baxter, Gerardo Ortiz, Roger Pynn, Michael Snow Quantum entanglement is a promising tool for improving measurement accuracy. Parity-odd neutron-matter interactions of the form $\vec{\sigma} \cdot \vec{p}$ can influence entangled neutron beams. We recently demonstrated neutron entanglement on the Larmor spectrometer at the ISIS facility through a series of quantum contextuality tests by breaking two types of inequalities. The Clauser-Horne-Shimony-Holt type inequality (for a neutron in Bell state of spin and position) and the Mermin type inequality (for Greenberger-Horne-Zeilinger state of spin, position and energy) were both violated with values beyond classical limit. These ``entanglement witnesses" are constructed by inserting different phase shifts in individual qubit subspaces and performing spin projection measurements. The minimal decoherence experienced by the neutrons passing through a bulk quartz phase shifter promises to open new avenues for neutron metrology with possible future applications to the NSR and NOPTREX experiments. Additionally, neutron Wollaston prisms similar to the devices employed in this work can help to generate and characterize orbital angular momentum states of the neutron. [Preview Abstract] |

## Follow Us |
## Engage
Become an APS Member |
## My APS
Renew Membership |
## Information for |
## About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |

© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us

**Headquarters**
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200

**Editorial Office**
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000

**Office of Public Affairs**
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700