Tue·Oct 25, 2016Tuesday·October 25, 2016

1. 01*

   Sensitivity of stellar electron-capture rates to parent neutron number: A case study on a continuous chain of twenty Vanadium isotopes

   G. W. Hitt · S. Gupta🇮🇳 · R. G. T. Zegers🇺🇸 · R. Titus · C. Sullivan · B. A. Brown🇺🇸 · A. L. Cole🇬🇧 · S. Shams

   Gamow-Teller (GT) strength distributions (B(GT)) in electron-capture (EC) daughters stemming from the parent ground state are computed with the shell-model in the full pf-shell space, with quasi-particle random-phase approximation (QRPA) in the formalism of Krumlinde and Möller and with an Approximate Method (AM) for assigning an effective B(GT). These are compared to data available from decay and charge-exchange (CE) experiments across titanium isotopes in the pf-shell from A=43 to A=62, the largest set available for any chain of isotopes in the pf-shell. The present study is the first to examine B(GT) and the associated EC rates across a particular chain of isotopes with the purpose of examining rate sensitivities as neutron number increases. EC rates are also computed for a wide variety of stellar electron densities and temperatures providing concise estimates of the relative size of rate sensitivities for particular astrophysical scenarios. This work underscores the astrophysical motivation for CE experiments in inverse kinematics for nuclei away from stability at the luminosities of future Radioactive Ion Beam Facilities.

   nucl-exastro-ph.SRnucl-th1 citation
2. 02*

   Directed flow of $\Lambda$, $\bar{\Lambda }$, $K^{\pm }$, $K_S^0$ and $\varphi$ mesons from Beam Energy Scan Au+Au collisions using the STAR experiment

   Subhash Singha (for the STAR collaboration)🇺🇸

   We report the results of $v_1$ and $d{v}_1/dy$ near mid-rapidity for $\Lambda$, $\bar{\Lambda }$, $K^{\pm }$, $K_s^0$ and $\varphi$ in Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}$ = 7.7, 11.5, 14.5, 19.6, 27 and 39~GeV using the STAR detector at RHIC. The $d{v}_1/dy$ of $\Lambda$ is found to be consistent with that of the proton and shows a change in sign near $\sqrt{s_{\mathrm{NN}}}=11.5$~GeV. The $v_1$ slope for $\bar{\Lambda }$, $\bar{p}$ and $\varphi$ shows a similar trend for $\sqrt{s_{\mathrm{NN}}}$ $>$ 14.5~GeV, while below 14.5~GeV, $\varphi$ $v_1$ is consistent with zero but with a large uncertainty. The $d{v}_1/dy$ for net protons and net kaons is similar for $\sqrt{s_{\mathrm{NN}}}>$ 14.5~GeV, but they deviate at lower beam energies.

   nucl-exhep-exnucl-thJ.Phys.Conf.Ser.(2017)·3 citations
3. 03*

   Characterization of the proposed 4-{\alpha} cluster state candidate in 16O

   K.C.W. Li🇿🇦 · R. Neveling🇿🇦 · P. Adsley🇿🇦 · P. Papka🇿🇦 · F.D. Smit🇿🇦 · J.W. Brümmer🇿🇦 · C. Aa. Diget · M. Freer🇬🇧 · M.N. Harakeh🇳🇱 · Tz. Kokalova🇬🇧 · F. Nemulodi🇿🇦 · L. Pellegri🇿🇦 and 5 other authors

   The ${}^{16}\mathrm{O}(\alpha ,{\alpha }^{\prime })$ reaction was studied at ${\theta }_{lab}=0^{\circ }$ at an incident energy of ${\text{E}}_{lab}$ = 200 MeV using the K600 magnetic spectrometer at iThemba LABS. Proton and $\alpha$-decay from the natural parity states were observed in a large-acceptance silicon-strip detector array at backward angles. The coincident charged particle measurements were used to characterize the decay channels of the $0_6^{+}$ state in ${}^{16}\mathrm{O}$ located at $E_x=15.097(5)$ MeV. This state is identified by several theoretical cluster calculations to be a good candidate for the 4-$\alpha$ cluster state. The results of this work suggest the presence of a previously unidentified resonance at $E_x\approx 15$ MeV that does not exhibit a $0^{+}$ character. This unresolved resonance may have contaminated previous observations of the $0_6^{+}$ state.

   nucl-exPRC(2017)·27 citations
4. 04*

   JLab Measurements of the 3He Form Factors at Large Momentum Transfers

   A. Camsonne🇺🇸 · A.T. Katramatou🇺🇸 · M. Olson🇺🇸 · A. Acha🇺🇸 · K. Allada🇺🇸 · B.D. Anderson🇺🇸 · J. Arrington🇺🇸 · A. Baldwin🇺🇸 · J.-P. Chen🇺🇸 · S. Choi🇰🇷 · E. Chudakov🇺🇸 · E. Cisbani🇮🇹 and 57 other authors

   The charge and magnetic form factors, FC and FM, of 3He have been extracted in the kinematic range 25 fm-2 < Q2 < 61 fm-2 from elastic electron scattering by detecting 3He recoil nuclei and electrons in coincidence with the High Resolution Spectrometers of the Hall A Facility at Jefferson Lab. The measurements are indicative of a second diffraction minimum for the magnetic form factor, which was predicted in the Q2 range of this experiment, and of a continuing diffractive structure for the charge form factor. The data are in qualitative agreement with theoretical calculations based on realistic interactions and accurate methods to solve the three-body nuclear problem.

   nucl-exPRL(2017)·14 citations
5. 05*

   Production of charmed baryon ${\Lambda }_c(2940)$ by kaon-induced reaction on a proton target

   Yin Huang · Jun He · Ju-Jun Xie · Xurong Chen · Hong-Fei Zhang

   We investigate the possibility to study the charmed baryon ${\Lambda }_c(2940)$ by kaon-induced reaction on a proton target. By assuming the ${\Lambda }_c(2940)$ as a $p{D}^{\ast 0}$ molecular state with spin-parity $J^p=1/2^{\pm }$, an effective Lagrangian approach was adopted to calculate the cross section, the $D^{0}p$ invariant mass spectrum and Dalitz plot of the $\Lambda (2940)$ production. The total cross section of the $K^{-}p\to {\Lambda }_c(2940)D_s^{-}$ reaction is found at an order of magnitude about 10 $\mu$b. By considering the sub sequential decay ${\Lambda }_c(2940)\to D^{0}p$ with contributions from the ${\Lambda }_c(2286)$ and the ${\Sigma }_c(2455)$ as background, the $K^{-}p\to D_s^{-}{D}^{0}p$ reaction are studied. It is found that the ${\Lambda }_c(2940)$ is produced mainly at forward angles. The ${\Lambda }_c(2940)$ signal is predicted to be significant in the $D^{0}p$ invariant mass spectrum and the Dalitz plot of the $K^{-}p\to D_s^{-}{D}^{0}p$ reaction. The results suggest that it is promising to study the ${\Lambda }_c(2940)$ with high-energy kaon beam on a proton target in experiment.

   ↳ hep-phhep-exnucl-exnucl-thPRD(2019)·19 citations
6. 06*

   Next Generation Muon g-2 Experiment at FNAL

   Martin Fertl🇺🇸

   The precise measurement of the muon anomalous magnetic moment $a_{\mu }$ has stimulated much theoretical and experimental efforts over more than six decades. The last experiment at Brookhaven National Laboratory, Upton, NY, USA obtained a value more than three standard deviations larger than predicted by the Standard Model of particle physics, and is one of the strongest hints for physics beyond the Standard Model. A new experiment at Fermi National Accelerator Laboratory, Batavia, IL, USA to measure $a_{\mu }$ with fourfold increased precision to $140\mathrm{ppb}$ is currently in its commissioning phase. While the new experiment will reuse the $1.45\mathrm{T}$ superconducting muon storage ring which was shipped from Brookhaven National Laboratory, most of the other instrumentation of the experiment will be new. This will allow the experiment to make efficient use of the significantly higher number of muons available at the new muon campus. We discuss the general status of the experiment and in particular focus on the improved tools available to homogenize and determine the magnetic field in the muon storage ring.

   ↳ physics.ins-dethep-exnucl-exHyperfine Interact.(2016)·3 citations
7. 07*

   Physics potential of searching for $0\nu \beta \beta$ decays in JUNO

   Jie Zhao🇨🇳 · Liang-Jian Wen🇨🇳 · Yi-Fang Wang🇨🇳 · Jun Cao🇨🇳

   In the past few decades, numerous searches have been made for the neutrinoless double-beta decay (0$\nu \beta \beta$) process, aiming to establish whether neutrinos are their own antiparticles (Majorana neutrinos), but no 0$\nu \beta \beta$ decay signal has yet been observed. A number of new experiments are proposed but they ultimately suffer from a common problem: the sensitivity may not increase indefinitely with the target mass. We have performed a detailed analysis of the physics potential by using the Jiangmen Underground Neutrino Observatory (JUNO) to improve the sensitivity to 0$\nu \beta \beta$ up to a few meV, a major step forward with respect to the experiments currently being planned. JUNO is a 20 kton low-background liquid scintillator (LS) detector with 3\%/$\sqrt{E\text{(MeV)}}$ energy resolution, now under construction. It is feasible to build a balloon filled with enriched xenon gas (with ${}^{136}$Xe up to 80\%) dissolved in LS, inserted into the central region of the JUNO LS. The energy resolution is $\sim$1.9\% at the $Q$-value of ${}^{136}$Xe 0$\nu \beta \beta$ decay. Ultra-low background is the key for 0$\nu \beta \beta$ decay searches. Detailed studies of background rates from intrinsic 2$\nu \beta \beta$ and ${}^8$B solar neutrinos, natural radioactivity, and cosmogenic radionuclides (including light isotopes and ${}^{137}$Xe) were performed and several muon veto schemes were developed. We find that JUNO has the potential to reach a sensitivity (at 90\% C. L.) to $T_{1/2}^{0\nu \beta \beta }$ of $1.8\times 10^{28}$ yr ($5.6\times 10^{27}$ yr) with $\sim$50 tons (5 tons) of fiducial ${}^{136}$Xe and 5 years exposure, while in the 50-ton case the corresponding sensitivity to the effective neutrino mass, $m_{\beta \beta }$, could reach (5--12) meV, covering completely the allowed region of inverted neutrino mass ordering.

   ↳ hep-exnucl-exphysics.ins-detCPC(2017)·44 citations
8. 08*

   The dynamic polarization potential and dynamical non-locality in nuclear potentials: Deuteron-nucleus potential

   R.S. Mackintosh · N.Keeley

   The consequences for direct reactions of the dynamical non-locality generated by the excitation of the target and projectile are much less studied than the effects of non-locality arising from exchange processes. Here we are concerned with the dynamical non-locality due to projectile excitation in deuteron induced reactions. The consequences of this non-locality can be studied by the comparison of deuteron induced direct reactions calculated with alternative representations of the elastic channel wave functions: (i) the elastic channel wave functions from coupled channel (CC) calculations involving specific reaction processes, and, (ii) elastic channel wave functions calculated from local potentials that exactly reproduce the elastic scattering $S$-matrix from the same CC calculations. In this work we produce the local equivalent deuteron potentials required for the study of direct reactions involving deuterons. These will enable the study of the effects of dynamical non-locality following a method previously employed in an investigation of the effects of non-locality due to target excitation. In this work we consider only excitations due to deuteron breakup, and some new properties of the breakup dynamical polarization potential (DPP) emerge that reveal dynamical non-locality directly. In addition, we evaluate the TELP inversion method and find that it fails to reproduce some features of the DPP due to breakup.

   ↳ nucl-thnucl-ex5 citations
9. 09*

   Dependence of X-ray Burst Models on Nuclear Masses

   H. Schatz🇺🇸 · W.-J. Ong🇺🇸

   X-ray burst model predictions of light curves and final composition of the nuclear ashes are affected by uncertain nuclear masses. However, not all of these masses are determined experimentally with sufficient accuracy. Here we identify remaining nuclear mass uncertainties in X-ray burst models using a one zone model that takes into account the changes in temperature and density evolution caused by changes in the nuclear physics. Two types of bursts are investigated - a typical mixed H/He burst with a limited rp-process and an extreme mixed H/He burst with an extended rp-process. When allowing for a 3$\sigma$ variation only three remaining nuclear mass uncertainties affect the light curve predictions of a typical H/He burst (${}^{27}$P, ${}^{61}$Ga, and ${}^{65}$As), and only three additional masses affect the composition strongly (${}^{80}$Zr, ${}^{81}$Zr, and ${}^{82}$Nb). A larger number of mass uncertainties remains to be addressed for the extreme H/He burst with the most important being ${}^{58}$Zn, ${}^{61}$Ga, ${}^{62}$Ge, ${}^{65}$As, ${}^{66}$Se, ${}^{78}$Y, ${}^{79}$Y, ${}^{79}$Zr, ${}^{80}$Zr, ${}^{81}$Zr, ${}^{82}$Zr, ${}^{82}$Nb, ${}^{83}$Nb, ${}^{86}$Tc, ${}^{91}$Rh, ${}^{95}$Ag, ${}^{98}$Cd, ${}^{99}$In, ${}^{100}$In, and ${}^{101}$In. The smallest mass uncertainty that still impacts composition significantly when varied by 3$\sigma$ is ${}^{85}$Mo with 16 keV uncertainty. For one of the identified masses, ${}^{27}$P, we use the isobaric mass multiplet equation (IMME) to improve the mass uncertainty, obtaining an atomic mass excess of -716(7) keV. The results provide a roadmap for future experiments at advanced rare isotope beam facilities, where all the identified nuclides are expected to be within reach for precision mass measurements.

   ↳ astro-ph.HEastro-ph.SRnucl-exApJ(2017)·55 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.