Bulletin of the American Physical Society
5th Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan
Volume 63, Number 12
Tuesday–Saturday, October 23–27, 2018; Waikoloa, Hawaii
Session FJ: Mini-Symposium on Fundamental Neutron Physics IV |
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Chair: Mike Snow, Indiana University Room: Hilton Kona 5 |
Friday, October 26, 2018 9:00AM - 9:30AM |
FJ.00001: Studying discrete symmetry violation in neutron-nucleus systems Invited Speaker: Takuya Okudaira
P-violation between nucleons resulting from the weak interaction is a valuable resource in the test of quantum chromodynamics (QCD). Few-body systems involving the neutron such as n+p, n+$^3$He, n+$4^$He and n+D may be used to determine parameters in effective field theories (EFT) which describe QCD in the non-perturbative limit. P-violation may appear as angular asymmetry of emitted particles or as P-odd spin rotation of neutrons transmitted through a nuclear target, and experiments to measure these observables with high sensitivity are in progress. Nucleon-nucleon (NN) P-violation also plays an important role in the search for T-violation using neutron-induced compound nuclear states. P-violation in the NN interaction may be enhanced by up to $10^6$ times in states such as $^{139}$La+n and $^{131}$Xe+n. T-violation may be enhanced by the same mechanism implying that a sensitive T-violation search might be possible using compound nuclei. Additionally, EFT parameters determined through measurements of P-violation are needed to estimate the sensitivity of a T-violation search. I will discuss experiments seeking to measure NN parity violation as well as a search for T-violation in compound nuclear systems. |
Friday, October 26, 2018 9:30AM - 9:45AM |
FJ.00002: Some theoretical aspects of Time-Reversal Invariance Violation in Neutron Scattering Vladimir Gudkov Time Reversal Invariance Violating (TRIV) effects in neutron transmission through nuclear targets are discussed. The absence of final state interactions for the set of specific observables makes these experiments complementary to neutron and atomic electric dipole moment (EDM) measurements. The approaches for a comparison of TRIV and the measured PV effects are discussed. We explore important advantages of the search for TRI violation in neutron nuclei interactions and show that neutron scattering experiments at new high flux Spallation Neutron Sources can essentially improve the current limits on the TRIV interactions obtained from neutron and atomic EDMs. |
Friday, October 26, 2018 9:45AM - 10:00AM |
FJ.00003: A Precision Measurement of the Parity Violation Present in the 0.734 eV p-wave Resonance in $^{139}$La Using the \lq{Double Lanthanum}\rq \ Technique: Preliminary Results and Analysis Danielle Schaper The Neutron OPtics Time Reversal EXperiment (NOPTREX) Collaboration aims to measure a potential time-reversal (T) violating process in neutron-nucleon forward scattering in parity (P) violating nuclear resonances. Because the proposed theoretical T-violating cross section is directly proportional to a P-violating cross section, precision spectroscopy of these resonances is of critical importance. In particular, the 0.734 eV p-wave resonance in $^{139}$La exhibits a ~10\% P-violation effect, making it an outstanding candidate for the NOPTREX experiment. We aim to measure this effect to 1\% precision, improving upon previous (room temperature) measurements by using cryogenic targets (15K) to reduce Doppler broadening effects as well as running for a longer period of time to reduce the statistical uncertainty. This experiment was conducted at LANSCE in 2017-2018. This talk will focus on the experimental setup, the preliminary data analysis and results, as well as future implications for the NOPTREX collaboration and additional parity-violation experiments on heavy nuclei. |
Friday, October 26, 2018 10:00AM - 10:15AM |
FJ.00004: Measurement of angular distribution of γ-rays in the resonance reaction of 139La for T-Violation search experiment Masaaki Kitaguchi, Shunsuke Endo, Takuhiro Fujiie, Hiroyuki Fujioka, Christopher Haddock, Katsuya Hirota, Masataka Iinuma, Kohei Ishizaki, Atsushi Kimura, Jun Koga, Sou Makise, Yudai Niinomi, Takayuki Oku, Takuya Okudaira, Kenji Sakai, Takumi Sato, Hirohiko M Shimizu, Shusuke Takada, Yuika Tani, Tomoki Yamamoto, Tamaki Yoshioka The parity violation in the neutron capture reaction of 139La was discovered with the enhancement million times larger than that in proton-proton scattering. The enhancement was observed at the neutron energy of 0.75 eV, which corresponds to p-wave resonance on the tail of large s-wave resonance peak. This was explained as the result of the entrance channel interference between the s- and p-wave amplitudes. The enhancement of T-violation is theoretically predicted with the same mechanism. The enhancement depends on the mixture of s- and p- partial waves in the compound state. |
Friday, October 26, 2018 10:15AM - 10:30AM |
FJ.00005: Experimental study for the sensitivity of T-violation search in the compound nuclear reaction of 117Sn Jun Koga, Shusuke Takada, So Makise, Tamaki Yoshioka, Hirohiko M Shimizu, Katsuya Hirota, Tomoki Yamamoto, Shunsuke Endo, Takumi Sato, Kohei Ishizaki, Yudai Niinomi, Takuhiro Fujiie, Masaaki Kitaguchi, Hiroyuki Fujioka, Yuika Tani, Masataka Iinuma, Takuya Okudaira, Atsushi Kimura, Kenji Sakai, Takayuki Oku, Christopher Haddock, Takashi Ino
CP-violation is necessary to explain the dominance of matter over antimatter in the current universe. To explain this, it is suggested that there is CP-violation in beyond the standard model. In the several compound nuclear reactions, P-violation is enhanced by a factor of 106 compared to the proton-proton scattering. This enhancement mechanism is theoretically explained as the interference between p- and s-wave resonances. It is theoretically suggested that CP-violation could be also enhanced by this mechanism. Considering the CPT theorem, it implies that T-violation could be enhanced. This theory predicts that the value of amplification factor for T-violation depends on nuclear species. The experiments to select the candidate nuclei for T-violation search are carried out at J-PARC. To determine the value of amplification factor of 117Sn, we measured the angular distribution of prompt gamma-rays emitted from compound states of Sn. Based on this result, we will discuss the experimental sensitivity of 117Sn for T-violation search. |
Friday, October 26, 2018 10:30AM - 10:45AM |
FJ.00006: Results From The NPDGamma Experiment: A New Measurement of the Parity-Violating Gamma Asymmetry in Polarized Neutron Capture on Protons Jason Fry The NPDGamma Experiment was performed to measure the parity-violating (PV) asymmetry in the angular distribution of gammas from polarized neutrons captured on protons at the Spallation Neutron Source in ORNL. This PV asymmetry $A_{\gamma}$ is proportional to the $\Delta I = 1$, $^3S_1\rightarrow^3P_1$ transition in the weak nucleon-nucleon interaction and is directly related to the long range pion coupling constant $h_{\pi}^1$ in the DDH meson exchange model and the low energy constant $C^{^3S_1\rightarrow^3P_1}/C_0^{^3S_1}$ in pionless effective field theory. We will present a description of the experiment, analysis, and the final result and its implications. |
Friday, October 26, 2018 10:45AM - 11:00AM |
FJ.00007: Final Results for the n3He Parity Violating Asymmetry Measurement Mark McCrea The goal of the n3He experiment was to measure the parity-violating directional asymmetry in the proton emission direction relative to the initial neutron polarization in the reaction $\vec{n}+^3\!He\rightarrow p+T+765$keV to a high precision. Data taking was completed at the end of 2015, and two independent analyses of the proton parity asymmetry have since been completed and are in agreement. I will present the methods used to calculate the asymmetry, and the final results with systematic and statistical uncertainties. |
Friday, October 26, 2018 11:00AM - 11:15AM |
FJ.00008: NDTGamma: A pulse-counting Hadronic Parity Violation experiment Christopher Blair Crawford Recent hadronic parity violation results from the NPDGamma and n3He experiments encourage us to envision a complete map of the spin and isospin dependence of the hadronic weak interaction with additional experiments. The remaining experimentally accessible observables in few-body systems pose special problems. The statistical precision of the parity-odd neutron spin asymmetry of gammas from n+d->t+γ, Aγnd from a practical target of D2O would be diluted by the low signal-to-background ratio if one measures the suppressed (~mb) n-D capture cross section using conventional analog integration of current-mode signals. Given the moderate event rates from this reaction and modern capabilities of high-speed digital pulse-processing electronics, we describe the possibility of detecting individual gamma-rays and discriminating on the 6.2 MeV photopeak. This would enable the first counting-mode measurement of hadronic parity violation in a few-body system. |
Friday, October 26, 2018 11:15AM - 11:30AM |
FJ.00009: Neutron Spin Rotation: A Non-Magnetic Liquid 4He Target System Kyle Steffen The rotation of a polarized neutron’s spin in liquid 4He provides experimental access to parity-violation in the nucleon-nucleon weak interaction (NNWI). Recent work in NNWI theory [1] [2] [3] has lead to a predicted value of the neutron spin rotation (NSR) angle in 4He of dφ/dz = 6.8×10−7 rad/m [4]. Previous experimental analysis from the NSR collaboration gives statistically-limited results at this order of magnitude. A new non-magnetic pump and target system, as well as interim upgrades to the NSR apparatus, are expected to achieve experimental sensitivity < [±1.0(stat.) ± 1.0(sys.)]×10−7 rad/m [5] on the NG-C beam at NIST – allowing for the first standard model test in the NNWI sector. The status of the NSR apparatus will be presented, with emphasis on the ongoing assembly of the target system. References [1] D. R. Phillips, D. Samart, and C. Schat, Phys. Rev. Lett. 114, 062301(2015). [2] D. Samart, C. Schat, M. R. Schindler, and D. R. Phillips, Phys. Rev. C 94, 024001 (2016). [3] M. R. Schindler, R. P. Springer, and J. Vanasse, Phys. Rev. C 93, 025502 (2016). [4] S. Gardner, W. C. Haxton, and B. R. Holstein, Ann. Rev. Nucl. Part. Sci. 67, 69 (2017). [5] W. M. Snow, Et Al., Rev. Sci. Inst. 86, 055101(2015) |
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