Wed·Oct 28, 2015Wednesday·October 28, 2015

1. 01*

   Observation of Doppler broadening in $\beta$-delayed proton-$\gamma$ decay

   S.B. Schwartz · C. Wrede · M.B. Bennett · S.N. Liddick · D. Perez-Loureiro · A. Bowe · A.A. Chen · K.A. Chipps · N. Cooper · D. Irvine · E. McNeice · F. Montes and 13 other authors

   Background: The Doppler broadening of $\gamma$-ray peaks due to nuclear recoil from $\beta$-delayed nucleon emission can be used to measure the energies of the nucleons. This method has never been tested using $\beta$-delayed proton emission or applied to a recoil heavier than $A=10$. Purpose: To test and apply this Doppler broadening method using $\gamma$-ray peaks from the ${}^{26}$P($\beta p\gamma$)${}^{25}$Al decay sequence. Methods: A fast beam of ${}^{26}$P was implanted into a planar Ge detector, which was used as a ${}^{26}$P $\beta$-decay trigger. The SeGA array of high-purity Ge detectors was used to detect $\gamma$ rays from the ${}^{26}$P($\beta p\gamma$)${}^{25}$Al decay sequence. Results: Radiative Doppler broadening in $\beta$-delayed proton-$\gamma$ decay was observed for the first time. The Doppler broadening analysis method was verified using the 1613 keV $\gamma$-ray line for which the proton energies were previously known. The 1776 keV $\gamma$ ray de-exciting the 2720 keV ${}^{25}$Al level was observed in ${}^{26}$P($\beta p\gamma$)${}^{25}$Al decay for the first time and used to determine that the center-of-mass energy of the proton emission feeding the 2720-keV level is 5.1 $\pm$ 1.0 (stat.) $\pm$ 0.6 (syst.) MeV, corresponding to a ${}^{26}$Si excitation energy of 13.3 $\pm$ 1.0 (stat.) $\pm$ 0.6 (syst.) MeV for the proton-emitting level. Conclusions: The Doppler broadening method has been demonstrated to provide practical measurements of the energies for $\beta$-delayed nucleon emissions populating excited states of nuclear recoils at least as heavy as $A=25$.

   nucl-exPRC(2015)·14 citations
2. 02*

   Recent results from NA61/SHINE

   Szymon Puławski (for the NA61/SHINE Collaboration)🇵🇱

   The main physics goals of the NA61/SHINE programme on strong interactions are the study of the properties of the onset of deconfinement and the search for signatures of the critical point of strongly interacting matter. These goals are pursued by performing an energy (beam momentum 13A -158A GeV/c) and system size (p+p, p+Pb, Be+Be, Ar+Sc, Xe+La) scan. This publication reviews results and plans of NA61/SHINE. In particular, recent inclusive spectra and new results on fluctuations and correlations of identified hadrons in inelastic p+p and centrality selected Be+Be interactions at the SPS energies are presented. The energy dependence of quantities inspired by the Statistical Model of the Early Stage (kink, horn and step) show unexpected behavior in p+p collisions. The NA61/SHINE results are compared with the corresponding data of other experiments and model predictions.

   nucl-exhep-exActa Phys.Polon.B(2015)·3 citations
3. 03*

   Baryon spectroscopy with polarization observables from CLAS

   Steffen Strauch (for the CLAS Collaboration)🇺🇸

   Meson photoproduction is an important tool in the study of baryon resonances. The spectrum of broad and overlapping nucleon excitations can be greatly clarified by use of polarization observables. The N* program at Jefferson Lab with the CEBAF Large Acceptance Spectrometer (CLAS) includes experimental studies with linearly and circularly polarized tagged photon beams, longitudinally and transversely polarized nucleon targets, and recoil polarizations. An overview of these experimental studies and recent results will be given.

   nucl-ex0 citations
4. 04*

   Measurement of angular correlations between $\mathrm{D}$ mesons and charged particles in pp and p-Pb collisions with ALICE at the LHC

   Somnath Kar (for the ALICE Collaboration)🇮🇳

   We have studied the azimuthal correlations between ${\mathrm{D}}^0$, ${\mathrm{D}}^{+}$ and ${\mathrm{D}}^{\ast +}$ mesons and charged particles in pp collisions at $\sqrt{s}=7\mathrm{TeV}$ and p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02\mathrm{TeV}$ at the Large Hadron Collider. D mesons were reconstructed from their hadronic decays in the central rapidity region and in the transverse-momentum range 3 $\le p_T\le$ 16 $\mathrm{GeV}/c$, and they were correlated to charged particles reconstructed in the pseudo-rapidity range $|\eta |<0.8$. A comparative study of the pp results with Monte Carlo Pythia studies and also with p-Pb results are presented here.

   ↳ hep-exnucl-exPoS(2017)·0 citations
5. 05*

   Development and Characterization of a High Sensitivity Segmented Fast Neutron Spectrometer (FaNS-2)

   FaNS Collaboration: T. J. Langford🇺🇸 · E. J. Beise🇺🇸 · H. Breuer🇺🇸 · C. R. Heimbach🇺🇸 · G. Ji · J. S. Nico🇺🇸

   We present the development of a segmented fast neutron spectrometer (FaNS-2) based upon plastic scintillator and ${}^3$He proportional counters. It was designed to measure both the flux and spectrum of fast neutrons in the energy range of few MeV to 1 GeV. FaNS-2 utilizes capture-gated spectroscopy to identify neutron events and reject backgrounds. Neutrons deposit energy in the plastic scintillator before capturing on a ${}^3$He nucleus in the proportional counters. Segmentation improves neutron energy reconstruction while the large volume of scintillator increases sensitivity to low neutron fluxes. A main goal of its design is to study comparatively low neutron fluxes, such as cosmogenic neutrons at the Earth's surface, in an underground environment, or from low-activity neutron sources. In this paper, we present details of its design and construction as well as its characterization with a calibrated ${}^{252}$Cf source and monoenergetic neutron fields of 2.5 MeV and 14 MeV. Detected monoenergetic neutron spectra are unfolded using a Singular Value Decomposition method, demonstrating a 5% energy resolution at 14 MeV. Finally, we discuss plans for measuring the surface and underground cosmogenic neutron spectra with FaNS-2.

   ↳ physics.ins-detastro-ph.IMnucl-exJINST(2016)·7 citations
6. 06*

   ${}^3\mathrm{He}(\alpha ,\gamma ){}^7\mathrm{Be}$ and ${}^3\mathrm{H}(\alpha ,\gamma ){}^7\mathrm{Li}$ astrophysical $S$ factors from the no-core shell model with continuum

   Jérémy Dohet-Eraly🇨🇦 · Petr Navrátil🇨🇦 · Sofia Quaglioni🇺🇸 · Wataru Horiuchi🇯🇵 · Guillaume Hupin🇫🇷 · Francesco Raimondi🇨🇦

   The ${}^3\mathrm{He}(\alpha ,\gamma ){}^7\mathrm{Be}$ and ${}^3\mathrm{H}(\alpha ,\gamma ){}^7\mathrm{Li}$ astrophysical $S$ factors are calculated within the no-core shell model with continuum using a renormalized chiral nucleon-nucleon interaction. The ${}^3\mathrm{He}(\alpha ,\gamma ){}^7\mathrm{Be}$ astrophysical $S$ factors agree reasonably well with the experimental data while the ${}^3\mathrm{H}(\alpha ,\gamma ){}^7\mathrm{Li}$ ones are overestimated. The seven-nucleon bound and resonance states and the $\alpha +{}^3\mathrm{He}/{}^3\mathrm{H}$ elastic scattering are also studied and compared with experiment. The low-lying resonance properties are rather well reproduced by our approach. At low energies, the $s$-wave phase shift, which is non-resonant, is overestimated.

   ↳ nucl-thastro-ph.SRnucl-exPLB(2016)·82 citations
7. 07*

   The influence of the Coulomb exchange term on nuclear single-proton resonances

   Shu-Yang Wang · Zhong-Lai Zhu · Zhong-Ming Niu🇨🇳

   Nuclear single-proton resonances are sensitive to the Coulomb field, while the exchange term of Coulomb field is usually neglected due to its nonlocality. By combining the complex scaling method with the relativistic mean-field model, the influence of the Coulomb exchange term on the single-proton resonances is investigated by taking Sn isotopes and $N=82$ isotones as examples. It is found that the Coulomb exchange term reduces the single-proton resonance energy within the range of $0.4-0.6$ MeV, and lead to similar isotopic and isotonic trends of the resonance energy as those without the Coulomb exchange term. Moreover, the single-proton resonance width is also reduced by the Coulomb exchange term, whose influence generally decreases with the increasing neutron number and increases with the increasing proton number. However, the influence of the Coulomb exchange term cannot change the trend of the resonance width with respect to the neutron number and proton number. Furthermore, the influence of the Coulomb exchange term on the resonance width is investigated for the doubly magic nuclei ${}^{40}$Ca, ${}^{56,78}$Ni, ${}^{100,132}$Sn, and ${}^{208}$Pb. It is found that the Coulomb exchange term reduces the proton resonance width within $0.2$ MeV, whose magnitude depends on the specific nucleus and the quantum numbers of resonant states.

   ↳ nucl-thnucl-exNucl.Sci.Tech.(2016)·6 citations
8. 08*

   Investigations on Important Properties of the 10 cm x 10 cm GEM Prototype

   Kiadtisak Saenboonruang🇹🇭 · Piyakul Kumphiranon🇹🇭 · Kittipong Kulasri🇹🇭 · Anawat Ritthirong🇹🇭

   The Gas Electron Multiplier (GEM) detector is one of promising particle and radiation detectors that has been improved greatly from previous gas detectors. The improvement includes better spatial resolutions, higher detection rate capabilities, and flexibilities in designs. In particular, the 10 cm x 10 cm GEM prototype is designed and provided by the Gas Detectors Development group (GDD) at CERN, Switzerland. With its simplicity in operations and designs, while still maintaining high qualities, the GEM prototype is suitable for both start-up and advanced researches. This article aims to report the investigations on some important properties of the 10 cm x 10 cm GEM detector using current measurement and signal counting. Results have shown that gains of the GEM prototype exponentially increase as voltage supplied to the detector increases, while the detector reaches full efficiency (plateau region) when the voltage is greater than 4100 V. In terms of signal sharing between X and Y strips of the readout, X strips, which is on the top layer of the readout, collect ~57% of the total signal. For the uniformity test, the GEM prototype has slightly higher efficiencies at the center of the detector and decreases as positions are closer to edges.

   ↳ physics.ins-detnucl-ex0 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.