Tue·Jan 5, 2016Tuesday·January 5, 2016

1. 01*

   Underground nuclear astrophysics: why and how

   A. Best🇮🇹 · A. Caciolli🇮🇹 · Zs. Fülöp🇭🇺 · Gy. Gyürky🇭🇺 · M. Laubenstein🇮🇹 · E. Napolitani🇮🇹 · V. Rigato🇮🇹 · V. Roca🇮🇹 · T. Szücs🇩🇪

   The goal of nuclear astrophysics is to measure cross sections of nuclear physics reactions of interest in astrophysics. At stars temperatures, these cross sections are very low due to the suppression of the Coulomb barrier. Cosmic ray induced background can seriously limit the determination of reaction cross sections at energies relevant to astrophysical processes and experimental setups should be arranged in order to improve the signal-to-noise ratio. Placing experiments in underground sites, however, reduces this background opening the way towards ultra low cross section determination. LUNA (Laboratory for Underground Nuclear Astrophysics) was pioneer in this sense. Two accelerators were mounted at the INFN National Laboratories of Gran Sasso (LNGS) allowing to study nuclear reactions close to stellar energies. A summary of the relevant technology used, including accelerators, target production and characterisation, and background treatment is given.

   nucl-exphysics.acc-phphysics.ins-detEPJA(2016)·26 citations
2. 02*

   Color transparency in ${\pi }^{-}$-induced dilepton production on nuclei

   A.B. Larionov🇩🇪 · M. Strikman🇺🇸 · M. Bleicher🇩🇪

   We argue that the observation of the color transparency effect in the semiexclusive $A({\pi }^{-},l^{+}{l}^{-})$ process is important for determining whether it is possible to extract the generalized parton distributions of the nucleon from the elementary reaction ${\pi }^{-}p\to l^{+}{l}^{-}n$ at $p_{\mathrm{lab}}=15-20$ GeV/c at small $|t|$ and large invariant mass of the dilepton pair $l^{+}{l}^{-}$. Assuming that the transverse size of the pionic $q\bar{q}$ pair in the hard interaction point is similar to the one in the reaction ${\gamma }^{\ast }p\to {\pi }^{+}n$ studied at JLab we predict large color transparency effects in the discussed kinematic range. We also suggest that the semiexclusive ${\rho }^0$ production in ${\pi }^{-}$-induced reactions in the same beam momentum region may provide new information on the dynamics of the interaction in the non-vacuum channel, while the $J/\psi$ production can be used to get information on $J/\psi N$ total interaction cross section.,

   ↳ nucl-thhep-exhep-phnucl-exPRC(2016)·10 citations
3. 03*

   A high-finesse Fabry-Perot cavity with a frequency-doubled green laser for precision Compton polarimetry at Jefferson Lab

   A. Rakhman🇺🇸 · M. Hafez · S. Nanda🇺🇸 · F. Benmokhtar🇺🇸 · A. Camsonne🇺🇸 · G.D. Cates🇺🇸 · M.M. Dalton🇺🇸 · G.B. Franklin🇺🇸 · M. Friend🇯🇵 · R.W. Michaels🇺🇸 · V. Nelyubin🇺🇸 · D.S. Parno🇺🇸 and 4 other authors

   A high-finesse Fabry-Perot cavity with a frequency-doubled continuous wave green laser (532~nm) has been built and installed in Hall A of Jefferson Lab for high precision Compton polarimetry. The infrared (1064~nm) beam from a ytterbium-doped fiber amplifier seeded by a Nd:YAG nonplanar ring oscillator laser is frequency doubled in a single-pass periodically poled MgO:LiNbO${}_3$ crystal. The maximum achieved green power at 5 W IR pump power is 1.74 W with a total conversion efficiency of 34.8\%. The green beam is injected into the optical resonant cavity and enhanced up to 3.7~kW with a corresponding enhancement of 3800. The polarization transfer function has been measured in order to determine the intra-cavity circular laser polarization within a measurement uncertainty of 0.7\%. The PREx experiment at Jefferson Lab used this system for the first time and achieved 1.0\% precision in polarization measurements of an electron beam with energy and current of 1.0~GeV and 50~$\mu$A.

   ↳ physics.ins-detnucl-exNucl.Instrum.Meth.A(2016)·9 citations
4. 04*

   A new neutrino source for the study of the solar neutrino physics in the vacuum-matter transition region

   Jae Won Shin · Myung-Ki Cheoun · Toshitaka Kajino

   Production of a neutrino source through proton induced reaction is studied by using the particle transport code, GEANT4. Unstable isotope such as ${}^{27}$Si can be produced when ${}^{27}$Al target is bombarded by 15 MeV energetic proton beams. Through the beta decay process of the unstable isotope, a new electron-neutrino source in the 1.0 $\sim$ 5.0 MeV energy range is obtained. Proton induced reactions are simulated with JENDL High Energy File 2007 (JENDL/HE-2007) data and other nuclear data. For radioactive decay processes, we use "G4RadioactiveDecay" model based on the Evaluated Nuclear Structure Data File (ENSDF). We suggest target systems required for future's solar neutrino experiments, in particular, for the vacuum-matter transition region. As for the detection system of the new neutrino source, we evaluate reaction rates for available radiochemical detectors and LENA type scintillator detector. Possibility of detecting sterile neutrinos is also discussed.

   ↳ astro-ph.IMastro-ph.SRnucl-exPRC(2016)·7 citations
5. 05*

   Chiral Magnetic Effect in Heavy Ion Collisions

   Jinfeng Liao🇺🇸

   The Chiral Magnetic Effect (CME) is a remarkable phenomenon that stems from highly nontrivial interplay of QCD chiral symmetry, axial anomaly, and gluonic topology. It is of fundamental importance to search for the CME in experiments. The heavy ion collisions provide a unique environment where a hot chiral-symmetric quark-gluon plasma is created, gluonic topological fluctuations generate chirality imbalance, and very strong magnetic fields $|\vec{\mathbf{B}}|\sim m_{\pi }^2$ are present during the early stage of such collisions. Significant efforts have been made to look for CME signals in heavy ion collision experiments. In this contribution we give a brief overview on the status of such efforts.

   ↳ nucl-thhep-phnucl-exNPA(2016)·20 citations
6. 06*

   The ALICE Transition Radiation Detector: status and perspectives for Run II

   Jochen Klein (for the ALICE Collaboration)🇨🇭

   The ALICE Transition Radiation Detector contributes to the tracking, particle identification, and triggering capabilities of the experiment. It is composed of six layers of multi-wire proportional chambers, each of which is preceded by a radiator and a Xe/CO${}_2$-filled drift volume. The signal is sampled in timebins of 100~ns over the drift length which allows for the reconstruction of chamber-wise track segments, both online and offline. The particle identification is based on the specific energy loss of charged particles and additional transition radiation photons, the latter being a signature for electrons. The detector is segmented into 18 sectors, of which 13 were installed in Run I. The TRD was included in data taking since the LHC start-up and was successfully used for electron identification and triggering. During the Long Shutdown 1, the detector was completed and now covers the full azimuthal acceptance. Furthermore, the readout and trigger components were upgraded. When data taking was started for \runii{}, their performance fulfilled the expectations.

   ↳ physics.ins-detnucl-ex3 citations
7. 07*

   Muon Identification with Muon Telescope Detector at the STAR Experiment

   T.C. Huang🇨🇳 · R. Ma🇺🇸 · B. Huang🇺🇸 · X. Huang🇨🇳 · L. Ruan🇺🇸 · T. Todoroki🇺🇸 · Z. Xu🇺🇸 · C. Yang🇨🇳 · S. Yang🇨🇳 · Q. Yang🇨🇳 · Y. Yang🇹🇼 · W. Zha🇨🇳

   Muon Telescope Detector (MTD) is a newly installed detector in the STAR experiment. It provides an excellent opportunity to study heavy quarkonium physics using the dimuon channel in heavy ion collisions. In this paper, we report the muon identification performance for the MTD using proton-proton collision at $\sqrt{s}$ = 500 GeV with various methods. The result using the Likelihood Ratio method shows that the muon identification efficiency can reach to $\sim$90% for muons with transverse momentum greater than 3 GeV/c and the significance of J/$\psi$ signal is improved by $\sim$40% compared to using the basic selection.

   ↳ physics.ins-dethep-exnucl-exNucl.Instrum.Meth.A(2016)·12 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.