Tue·Sep 18, 2018Tuesday·September 18, 2018

1. 01*

   Spin-Dependent DIS from Polarized ${}^3$He at EIC

   Richard Milner🇺🇸

   A day-1 EIC detector should be prepared to carry out inclusive DIS measurements from electron collisions with nucleon and nuclear beams. Here I consider the scientific motivation for spin-dependent DIS measurements from a polarized ${}^3$He beam. Longitudinally polarized ${}^3$He ions can be used to measure $g_1^n(x,Q^2)$ in purely inclusive scattering. I also consider spin-dependent DIS from polarized ${}^3$He by tagging the spectator proton or deuteron in coincidence with the scattered electron. A calculation of high energy scattering from the polarized ${}^3$He nucleus in the EIC frame is motivated. Further, this type of measurement can be extended to other polarized few-body nuclei. High energy spin-dependent scattering from polarized ${}^3$He with tagged proton and deuteron could be studied experimentally ahead of EIC using spin-dependent proton-${}^3$He scattering in RHIC, when polarized ${}^3$He ions become available.

   nucl-ex3 citations
2. 02*

   Highlights from the STAR experiment

   Zhenyu Ye (for the STAR collaboration)🇺🇸

   The STAR experiment at the Relativistic Heavy Ion Collider (RHIC) studies properties and phase transitions of nuclear matter in various nucleus-nucleus collisions at center-of-mass energies per nucleon collision $\sqrt{s_{NN}}=7.7$-200 GeV. With a fixed target made of gold foils installed inside the beam pipe, STAR also starts to explore high baryon density regime (${\mu }_B\approx 420$-720 MeV) at $\sqrt{s_{NN}}=3.0$-7.7 GeV. A few selected results reported by the STAR collaboration at the Quark Matter 2018 (QM2018) conference are described in these proceedings.

   nucl-exNPA(2019)·7 citations
3. 03*

   Shape Coexistence and Mixing of Low-Lying $0^{+}$ States in ${}^{96}$Sr

   S. Cruz🇨🇦 · P.C. Bender🇨🇦 · R. Krücken🇨🇦 · K. Wimmer🇯🇵 · F. Ames🇨🇦 · C. Andreoiu🇨🇦 · R.A.E. Austin🇨🇦 · C.S. Bancroft🇺🇸 · R. Braid🇺🇸 · T. Bruhn🇨🇦 · W.N. Catford🇬🇧 · A. Cheeseman🇨🇦 and 23 other authors

   The low energy excited $0_{2,3}^{+}$ states in ${}^{96}$Sr are amongst the most prominent examples of shape coexistence across the nuclear landscape. In this work, the neutron $[2s_{1/2}{]}^2$ content of the $0_{1,2,3}^{+}$ states in ${}^{96}$Sr was determined by means of the d(${}^{95}$Sr,p) transfer reaction at the TRIUMF-ISAC2 facility using the SHARC and TIGRESS arrays. Spectroscopic factors of 0.19(3) and 0.22(3) were extracted for the ${}^{96}$Sr ground and 1229~keV $0^{+}$ states, respectively, by fitting the experimental angular distributions to DWBA reaction model calculations. A detailed analysis of the $\gamma$-decay of the isomeric $0_3^{+}$ state was used to determine a spectroscopic factor of 0.33(13). The experimental results are compared to shell model calculations, which predict negligible spectroscopic strength for the excited $0^{+}$ states in ${}^{96}$Sr. The strengths of the excited $0_{2,3}^{+}$ states were also analyzed within a two-level mixing model and are consistent with a mixing strength of $a^2$=0.40(14) and a difference in intrinsic deformations of $|\Delta \beta |=0.31(3)$. These results suggest coexistence of three different configurations in ${}^{96}$Sr and strong shape mixing of the two excited $0^{+}$ states.

   nucl-exnucl-thPLB(2018)·23 citations
4. 04*

   A measurement of the scintillation decay time constant of nuclear recoils in liquid xenon with the XMASS-I detector

   XMASS Collaboration: K. Abe🇯🇵 · K. Hiraide🇯🇵 · K. Ichimura🇯🇵 · Y. Kishimoto🇯🇵 · K. Kobayashi🇯🇵 · M. Kobayashi🇯🇵 · S. Moriyama🇯🇵 · M. Nakahata🇯🇵 · H. Ogawa🇯🇵 · K. Sato🇯🇵 · H. Sekiya🇯🇵 · T. Suzuki🇯🇵 and 25 other authors

   We report an in-situ measurement of the nuclear recoil (NR) scintillation decay time constant in liquid xenon (LXe) using the XMASS-I detector at the Kamioka underground laboratory in Japan. XMASS-I is a large single-phase LXe scintillation detector whose purpose is the direct detection of dark matter via NR which can be induced by collisions between Weakly Interacting Massive Particles (WIMPs) and a xenon nucleus. The inner detector volume contains 832 kg of LXe. ${}^{252}$Cf was used as an external neutron source for irradiating the detector. The scintillation decay time constant of the resulting neutron induced NR was evaluated by comparing the observed photon detection times with Monte Carlo simulations. Fits to the decay time prefer two decay time components, one for each of the Xe${}_2^{\ast }$ singlet and triplet states, with ${\tau }_S$ = 4.3$\pm$0.6 ns taken from prior research, ${\tau }_T$ was measured to be 26.9${}_{-1.1}^{+0.7}$ ns with a singlet state fraction F${}_S$ of 0.252${}_{-0.019}^{+0.027}$.We also evaluated the performance of pulse shape discrimination between NR and electron recoil (ER) with the aim of reducing the electromagnetic background in WIMP searches. For a 50\% NR acceptance, the ER acceptance was 13.7$\pm$1.0\% and 4.1$\pm$0.7\% in the energy ranges of 5--10 keV${}_{\mathrm{ee}}$ and 10--15 keV${}_{\mathrm{ee}}$, respectively.

   ↳ physics.ins-dethep-exnucl-exJINST(2018)·16 citations
5. 05*

   Proton charge radius extraction from electron scattering data using dispersively improved chiral effective field theory

   J. M. Alarcón🇪🇸 · D. W. Higinbotham🇺🇸 · C. Weiss🇺🇸 · Z. Ye🇺🇸

   We extract the proton charge radius from the elastic form factor (FF) data using a novel theoretical framework combining chiral effective field theory and dispersion analysis. Complex analyticity in the momentum transfer correlates the behavior of the spacelike FF at finite $Q^2$ with the derivative at $Q^2=0$. The FF calculated in the predictive theory contains the radius as a free parameter. We determine its value by comparing the predictions with a descriptive global fit of the spacelike FF data, taking into account the theoretical and experimental uncertainties. Our method allows us to use the finite-$Q^2$ FF data for constraining the radius (up to $Q^2\sim$ 0.5 GeV${}^2$ and larger) and avoids the difficulties arising in methods relying on the $Q^2\to 0$ extrapolation. We obtain a radius of 0.844(7) fm, consistent with the high-precision muonic hydrogen results.

   ↳ hep-phhep-latnucl-exnucl-th+1PRC(2019)·72 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.