Fri·Dec 20, 2019Friday·December 20, 2019

1. 01*

   Survey of deformation in nuclei in order to estimate the enhancement of sensitivity to atomic EDM

   Prajwal Mohanmurthy🇨🇭 · Umesh Silwal · Durga P. Siwakoti · Jeff A. Winger🇺🇸

   The observed baryon asymmetry of the universe (BAU) cannot be explained by the known sources of charge-parity (CP)-violation in the Standard Model (SM). A non-zero permanent electric-dipole-moment (EDM) for fundamental particles, nuclei or atoms, violates CP. Measuring a non-zero EDM allows us to gain a handle on additional sources of CP-violation required to explain the observed BAU. The EDM of an atom with an octupole and quadrupole deformed nucleus is enhanced. Therefore, the search for such atoms has become important in the quest to measure an EDM. Viability of EDM searches in ${}^{225}$Ra atoms with a deformed nucleus have already been demonstrated. We have performed a comprehensive survey for possible EDM candidates from a list of octupole deformed nuclei predicted by various theoretical models. Our search of long-lived isotopes with nuclear deformations comparable to or better than ${}^{225}$Ra results in a handful of viable candidates for future atomic EDM experiments based out of the Facility for Rare Isotope Beams (FRIB): ${}^{221}$Rn, ${}^{221,223,227}$Fr, ${}^{221,223,225}$Ra, ${}^{223,225,227}$Ac, ${}^{229}$Th, and particularly ${}^{229}$Pa. Furthermore, nuclei of ${}^{223,225}$Rn, ${}^{225}$Fr and ${}^{226}$Ac are also highly quadrupole and octupole deformed, but their ground state parity doublet energy difference has not yet been measured.

   nucl-exnucl-thAIP Conf.Proc.(2020)·6 citations
2. 02*

   Neutron lifetime beam anomaly and possible explanation

   A. P. Serebrov🇷🇺

   The review of experimental measurements of neutron lifetime is presented. Latest measurements with gravitational trap (PNPI NRC KI) and magnetic trap (LANL, USA) confirmed the result obtained by PNPI group in 2005. The results of measurements performed using UCN storing method are in good agreement; however, there is a significant discrepancy at 3.6{\sigma} (1% of decay probability) level with beam method experiment. The latest most accurate measurements of the neutron decay asymmetry and neutron lifetime measurements by storage method are in agreement within the Standard Model. This article discusses the possible causes of discrepancy in the measurements of the neutron lifetime. The most probable cause, apparently, is the loss of protons in beam method experiment during storage in a magnetic trap due to charge exchange collisions of protons with the residual gas. The proton becomes neutral and leaves the trap, which leads to a decrease in the number of registered protons, i.e. to a decrease in the probability of neutron decay or to an increase in the measured neutron lifetime.

   nucl-ex2 citations
3. 03*

   Data blinding for the nEDM experiment at PSI

   N. J. Ayres🇬🇧 · G. Ban🇫🇷 · G. Bison🇨🇭 · K. Bodek🇵🇱 · V. Bondar🇨🇭 · E. Chanel🇨🇭 · P.-J. Chiu🇨🇭 · C. Crawford🇺🇸 · M. Daum🇨🇭 · S. Emmenegger🇨🇭 · L. Ferraris-Bouchez🇫🇷 · P. Flaux🇫🇷 and 33 other authors

   Psychological bias towards, or away from, a prior measurement or a theory prediction is an intrinsic threat to any data analysis. While various methods can be used to avoid the bias, e.g. actively not looking at the result, only data blinding is a traceable and thus trustworthy method to circumvent the bias and to convince a public audience that there is not even an accidental psychological bias. Data blinding is nowadays a standard practice in particle physics, but it is particularly difficult for experiments searching for the neutron electric dipole moment, as several cross measurements, in particular of the magnetic field, create a self-consistent network into which it is hard to inject a fake signal. We present an algorithm that modifies the data without influencing the experiment. Results of an automated analysis of the data are used to change the recorded spin state of a few neutrons of each measurement cycle. The flexible algorithm is applied twice to the data, to provide different data to various analysis teams. This gives us the option to sequentially apply various blinding offsets for separate analysis steps with independent teams. The subtle modification of the data allows us to modify the algorithm and to produce a re-blinded data set without revealing the blinding secret. The method was designed for the 2015/2016 measurement campaign of the nEDM experiment at the Paul Scherrer Institute. However, it can be re-used with minor modification for the follow-up experiment n2EDM, and may be suitable for comparable efforts.

   ↳ physics.data-anhep-exnucl-exphysics.ins-detEPJA(2021)·5 citations
4. 04*

   Nuclear and neutron-star matter from local chiral interactions

   D. Lonardoni🇺🇸 · I. Tews🇺🇸 · S. Gandolfi🇺🇸 · J. Carlson🇺🇸

   We report a quantum Monte Carlo calculation of the equation of state of symmetric nuclear matter using local interactions derived from chiral effective field theory up to next-to-next-to-leading order fit to few-body observables only. The empirical saturation density and energy are well reproduced within statistical and systematic uncertainties. We have also derived the symmetry energy as a function of the density, finding good agreement with available experimentally derived constraints at saturation and twice saturation density. We find that the corresponding pressure is also in excellent agreement with recent constraints extracted from gravitational waves of the neutron-star merger GW170817 by the LIGO-Virgo detection.

   ↳ nucl-thastro-ph.HEnucl-exPRResearch(2020)·108 citations
5. 05*

   Measurement of BAS-TR imaging plate response to energetic aluminum ions

   J. Won · J. Song · S. Palaniyappan · D. C. Gautier · W. Jeong · J. C. Fernández · W. Bang

   We measured the response of BAS-TR imaging plate (IP) to energetic aluminum ions in the 0 to 222 MeV energy range, and compared it with predictions from a Monte Carlo simulation code using two different IP models. Energetic aluminum ions were produced with an intense laser pulse, and the response was evaluated from cross-calibration between CR-39 track detector and IP energy spectrometer. For the first time, we obtained the response function of the BAS-TR IP for aluminum ions in the energy range from 0 to 222 MeV. Notably the IP sensitivity in the exponential model is nearly constant from 36 MeV to 160 MeV.

   ↳ physics.ins-dethep-exnucl-exphysics.plasm-ph0 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.