Thu·Oct 27, 2016Thursday·October 27, 2016

1. 01*

   Repolarization of Negative Muons by Polarized ${}^{209}$Bi Nuclei

   R. Kadono🇯🇵 · J. Imazato🇯🇵 · T. Ishikawa🇯🇵 · K. Nishiyama🇯🇵 · K. Nagamine🇯🇵 · T. Yamazaki🇯🇵 · A. Bosshard🇨🇭 · M. Döbeli🇨🇭 · L. van Elmbt🇨🇭 · M. Schaad🇨🇭 · P. Truöl🇨🇭 · A. Bay🇨🇭 and 4 other authors

   A large ${\mu }^{-}$ polarization was achieved in muonic Bi atoms with the help of the strong hyperfine field in a polarized nuclear target. Using ${}^{209}$Bi nuclei polarized to ($59\pm 9$)% in ferromagnetic BiMn, we observed a $\mu$-$e$ decay asymmetry of ($13.1\pm 3.9$)%, which gives ${\mu }^{-}$ polarization per nuclear polarization equal to $-1.07\pm 0.35$. This value is almost consistent with $-0.792$ calculated for nuclei with spin $I=\frac{9}{2}$ and a positive magnetic moment under the assumption that the hyperfine interaction becomes effective in the lowest muonic states.

   nucl-exPRL(1986)·9 citations
2. 02*

   The decay characteristic of ${}^{22}$Si and its ground-state mass significantly affected by three-nucleon forces

   X. X. Xu🇨🇳 · C. J. Lin · L. J. Sun🇨🇳 · J. S. Wang🇨🇳 · Y. H. Lam🇨🇳 · J. Lee🇺🇸 · D. Q. Fang🇨🇳 · Z. H. Li · N. A. Smirnova🇫🇷 · C. X. Yuan🇨🇳 · L. Yang🇺🇸 · Y. T. Wang🇨🇳 and 33 other authors

   The decay of the proton-rich nucleus ${}^{22}$Si was studied by a silicon array coupled with germanium clover detectors. Nine charged-particle groups are observed and most of them are recognized as $\beta$-delayed proton emission. A charged-particle group at 5600 keV is identified experimentally as $\beta$-delayed two-proton emission from the isobaric analog state of ${}^{22}$Al. Another charged-particle emission without any $\beta$ particle at the low energy less than 300 keV is observed. The half-life of ${}^{22}$Si is determined as 27.5 (18) ms. The experimental results of $\beta$-decay of ${}^{22}$Si are compared and in nice agreement with shell-model calculations. The mass excess of the ground state of ${}^{22}$Si deduced from the experimental data shows that three-nucleon (3N) forces with repulsive contributions have significant effects on nuclei near the proton drip line.

   nucl-ex4 citations
3. 03*

   Excitation function of the alpha particle induced nuclear reactions on enriched ${}^{116}$Cd, production of the theranostic isotope ${}^{117m}$Sn

   F. Ditrói · S. Takács · H. Haba🇯🇵 · Y. Komori · M. Aikawa · Z. Szűcs · M. Saito

   ${}^{117m}$Sn is one of the radioisotopes can be beneficially produced through alpha particle irradiation. The targets were prepared by deposition of ${}^{116}$Cd metal onto high purity 12 $\mu$m thick Cu backing. The average deposited thickness was 21.9 $\mu$m. The beam energy was thoroughly measured by Time of Flight (TOF) methods and proved to be 51.2 MeV. For the experiment the well-established stacked foil technique was used. In addition to the Cd targets, Ti foils were also inserted into the stacks for energy and intensity monitoring. The Cu backings were also used for monitoring and as recoil catcher of the reaction products from the cadmium layer. The activities of the irradiated foils were measured with HPGe detector for gamma-ray spectrometry and cross section values were determined. As a result excitation functions for the formation of ${}^{117m}$Sn, ${}^{117m,g}$In, ${}^{116m}$In, ${}^{115m}$In and ${}^{115m,g}$Cd from enriched ${}^{116}$Cd were deduced and compared with the available literature data and with the results of the nuclear reaction model code calculations EMPIRE 3.2 and TALYS 1.8. Yield curves were also deduced for the measured nuclear reactions and compared with the literature.

   nucl-exNucl.Instrum.Meth.B(2016)·5 citations
4. 04*

   Overview of recent azimuthal correlation measurements from ALICE

   You Zhou (for the ALICE Collaboration)🇩🇰

   Azimuthal correlations are a powerful tool to probe the properties and the evolution of the collision system. In this proceedings, we will review the recent azimuthal correlation measurements from ALICE at the LHC. The comparison to other experimental measurements and various theoretical calculations will be discussed as well.

   nucl-exnucl-thEPJ Web Conf.(2017)·2 citations
5. 05*

   Atomki anomaly and dark matter in a radiative seesaw model with gauged $B-L$ symmetry

   Osamu Seto🇯🇵 · Takashi Shimomura🇯🇵

   Motivated by recently reported anomalies in a decay of an excited state of beryllium by the Atomki collaboration, we study a radiative seesaw model with gauged $B-L$ symmetry and a $Z_2$ parity. Assuming that the anomalies originate from the decay of the $B-L$ gauge boson followed by the nuclear decay, the mass of the lightest right-handed neutrino or the dark matter candidate can be determined below $10$ GeV. We show that for this mass range, the model can explain the anomalies in the beryllium decay and the relic dark matter abundance consistent with neutrino masses. We also predict its spin-independent cross section in direct detection experiments for this mass range.

   ↳ hep-phhep-exnucl-exnucl-thPRD(2017)·52 citations
6. 06*

   Event generator tuning using Bayesian optimization

   Philip Ilten🇺🇸 · Mike Williams🇺🇸 · Yunjie Yang🇺🇸

   Monte Carlo event generators contain a large number of parameters that must be determined by comparing the output of the generator with experimental data. Generating enough events with a fixed set of parameter values to enable making such a comparison is extremely CPU intensive, which prohibits performing a simple brute-force grid-based tuning of the parameters. Bayesian optimization is a powerful method designed for such black-box tuning applications. In this article, we show that Monte Carlo event generator parameters can be accurately obtained using Bayesian optimization and minimal expert-level physics knowledge. A tune of the PYTHIA 8 event generator using $e^{+}{e}^{-}$ events, where 20 parameters are optimized, can be run on a modern laptop in just two days. Combining the Bayesian optimization approach with expert knowledge should enable producing better tunes in the future, by making it faster and easier to study discrepancies between Monte Carlo and experimental data.

   ↳ physics.data-anhep-exnucl-exJINST(2017)·35 citations
7. 07*

   Comparison of ultracold neutron sources for fundamental physics measurements

   G. Bison🇨🇭 · M. Daum🇨🇭 · K. Kirch🇨🇭 · B. Lauss🇨🇭 · D. Ries🇨🇭 · P. Schmidt-Wellenburg🇨🇭 · G. Zsigmond🇨🇭 · T. Brenner🇫🇷 · P. Geltenbort🇫🇷 · T. Jenke🇫🇷 · O. Zimmer🇫🇷 · M. Beck🇩🇪 and 11 other authors

   Ultracold neutrons (UCNs) are key for precision studies of fundamental parameters of the neutron and in searches for new CP violating processes or exotic interactions beyond the Standard Model of particle physics. The most prominent example is the search for a permanent electric dipole moment of the neutron (nEDM). We have performed an experimental comparison of the leading UCN sources currently operating. We have used a 'standard' UCN storage bottle with a volume of 32 liters, comparable in size to nEDM experiments, which allows us to compare the UCN density available at a given beam port.

   ↳ physics.ins-detnucl-exPRC(2017)·42 citations
8. 08*

   ${\gamma }^{\ast }N\to N^{\ast }(1520)$ form factors in the timelike regime

   G. Ramalho🇧🇷 · M.T. Peña🇵🇹

   The covariant spectator quark model, tested before in a variety of electromagnetic baryon excitations, is applied here to the ${\gamma }^{\ast }N\to N^{\ast }(1520)$ reaction in the timelike regime. The transition form factors are first parametrized in the spacelike region in terms of a valence quark core model together with a parametrization of the meson cloud contribution. The form factor behavior in the timelike region is then predicted, as well as the $N^{\ast }(1520)\to \gamma N$ decay width and the $N^{\ast }(1520)$ Dalitz decay, $N^{\ast }(1520)\to e^{+}{e}^{-}N$. Our results may help in the interpretation of dielectron production from elementary $pp$ collisions and from the new generation of HADES results using a pion beam. In the $q^2=0$--1 GeV${}^2$ range we conclude that the {\it QED approximation} (a $q^2$ independent form factor model) underestimates the electromagnetic coupling of the $N^{\ast }(1520)$ from 1 up to 2 orders of magnitude. We conclude also that the $N^{\ast }(1520)$ and the $\Delta (1232)$ Dalitz decay widths are comparable.

   ↳ nucl-thhep-exhep-phnucl-exPRD(2017)·40 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.