Wed·Apr 13, 2016Wednesday·April 13, 2016

1. 01*

   Isomer shift and magnetic moment of the long-lived 1/2${}^{+}$ isomer in ${}_{30}^{79}$Zn${}_{49}$: signature of shape coexistence near ${}^{78}$Ni

   X.F. Yang🇧🇪 · C. Wraith🇬🇧 · L. Xie🇬🇧 · C. Babcock🇬🇧 · J. Billowes🇬🇧 · M.L. Bissell🇧🇪 · K. Blaum🇩🇪 · B. Cheal🇬🇧 · K.T. Flanagan🇬🇧 · R.F. Garcia Ruiz🇧🇪 · W. Gins🇧🇪 · C. Gorges🇩🇪 and 12 other authors

   Collinear laser spectroscopy has been performed on the ${}_{30}^{79}$Zn${}_{49}$ isotope at ISOLDE-CERN. The existence of a long-lived isomer with a few hundred milliseconds half-life was confirmed, and the nuclear spins and moments of the ground and isomeric states in ${}^{79}$Zn as well as the isomer shift were measured. From the observed hyperfine structures, spins $I=9/2$ and $I=1/2$ are firmly assigned to the ground and isomeric states. The magnetic moment $\mu$ (${}^{79}$Zn) = $-$1.1866(10) ${\mu }_{\mathrm{N}}$, confirms the spin-parity $9/2^{+}$ with a $\nu g_{9/2}^{-1}$ shell-model configuration, in excellent agreement with the prediction from large scale shell-model theories. The magnetic moment $\mu$ (${}^{79m}$Zn) = $-$1.0180(12) ${\mu }_{\mathrm{N}}$ supports a positive parity for the isomer, with a wave function dominated by a 2h-1p neutron excitation across the $N=50$ shell gap. The large isomer shift reveals an increase of the intruder isomer mean square charge radius with respect to that of the ground state: $\delta ⟨r_c^2{⟩}^{79,79m}$ = +0.204(6) fm${}^2$, providing first evidence of shape coexistence.

   nucl-exnucl-thPRL(2016)·87 citations
2. 02*

   Frontiers in Nuclear Astrophysics

   Carlos A. Bertulani🇺🇸 · Toshitaka Kajino🇯🇵

   The synthesis of nuclei in diverse cosmic scenarios is reviewed, with a summary of the basic concepts involved before a discussion of the current status in each case is made. We review the physics of the early universe, the proton to neutron ratio influence in the observed helium abundance, reaction networks, the formation of elements up to beryllium, the inhomogeneous Big Bang model, and the Big Bang nucleosynthesis constraints on cosmological models. Attention is paid to element production in stars, together with the details of the pp chain, the pp reaction, ${}^3$He formation and destruction, electron capture on ${}^7$Be, the importance of ${}^8$B formation and its relation to solar neutrinos, and neutrino oscillations. Nucleosynthesis in massive stars is also reviewed, with focus on the CNO cycle and its hot companion cycle, the rp-process, triple-$\alpha$ capture, and red giants and AGB stars. The stellar burning of carbon, neon, oxygen, and silicon is presented in a separate section, as well as the slow and rapid nucleon capture processes and the importance of medium modifications due to electrons also for pycnonuclear reactions. The nucleosynthesis in cataclysmic events such as in novae, X-ray bursters and in core-collapse supernovae, the role of neutrinos, and the supernova radioactivity and light-curve is further discussed, as well as the structure of neutron stars and its equation of state. A brief review of the element composition found in cosmic rays is made in the end.

   ↳ nucl-thastro-ph.COastro-ph.SRnucl-exPPNP(2016)·101 citations
3. 03*

   New application of superconductors: high sensitivity cryogenic light detectors

   L. Cardani🇮🇹 · F. Bellini🇮🇹 · N. Casali🇮🇹 · M. G. Casellano · I. Colantoni🇮🇹 · A. Coppolecchia🇮🇹 · C. Cosmelli🇮🇹 · A. Cruciani🇮🇹 · A. D'Addabbo🇮🇹 · S. Di Domizio🇮🇹 · M. Martinez🇮🇹 · C. Tomei🇮🇹 · M. Vignati🇮🇹

   In this paper we describe the current status of the CALDER project, which is developing ultra-sensitive light detectors based on superconductors for cryogenic applications. When we apply an AC current to a superconductor, the Cooper pairs oscillate and acquire kinetic inductance, that can be measured by inserting the superconductor in a LC circuit with high merit factor. Interactions in the superconductor can break the Cooper pairs, causing sizable variations in the kinetic inductance and, thus, in the response of the LC circuit. The continuous monitoring of the amplitude and frequency modulation allows to reconstruct the incident energy with excellent sensitivity. This concept is at the basis of Kinetic Inductance Detectors (KIDs), that are characterized by natural aptitude to multiplexed read-out (several sensors can be tuned to different resonant frequencies and coupled to the same line), resolution of few eV, stable behavior over a wide temperature range, and ease in fabrication. We present the results obtained by the CALDER collaboration with 2x2 cm2 substrates sampled by 1 or 4 Aluminum KIDs. We show that the performances of the first prototypes are already competitive with those of other commonly used light detectors, and we discuss the strategies for a further improvement.

   ↳ physics.ins-detastro-ph.IMnucl-exNucl.Instrum.Meth.A(2017)·3 citations
4. 04*

   Exotic vector charmonium and its leptonic decay width

   Ying Chen🇨🇳 · Wei-Feng Chiu🇨🇳 · Ming Gong🇨🇳 · Long-Cheng Gui🇨🇳 · Zhaofeng Liu🇨🇳

   We propose a novel type of interpolating field operators, which manifests the hybrid-like configuration that the charm quark-antiquark pair recoils against gluonic degrees of freedom. A heavy vector charmonium-like state with a mass of $4.33(2)\mathrm{GeV}$ is disentangled from the conventional charmonium states in the quenched approximation. This state has affinity for the hybrid-like operators but couples less to the relevant quark bilinear operator. We also try to extract its leptonic decay constant and give a tentative upper limit that it is less than one tenth of that of $J/\psi$, which corresponds to a leptonic decay width about dozens of eV. The connection of this state with $X(4260)$ is also discussed.

   ↳ hep-lathep-phnucl-exCPC(2016)·32 citations
5. 05*

   Charge symmetry breaking in the A=4 hypernuclei

   Daniel Gazda🇸🇪 · Avraham Gal🇮🇱

   Charge symmetry breaking (CSB) in the $\Lambda$-nucleon strong interaction generates a charge dependence of $\Lambda$ separation energies in mirror hypernuclei, which in the case of the $A=4$ mirror hypernuclei $0^{+}$ ground states is sizable, $\Delta B_{\Lambda }^{J=0}\equiv B_{\Lambda }^{J=0}{(}_{\Lambda }^4\mathrm{He})-B_{\Lambda }^{J=0}{(}_{\Lambda }^4\mathrm{H})=230\pm 90$ keV, and of opposite sign to that induced by the Coulomb repulsion in light hypernuclei. Recent ab-initio calculations of the (${}_{\Lambda }^4\mathrm{H},{}_{\Lambda }^4\mathrm{He}$) mirror hypernuclei $0_{g.s.}^{+}$ and $1_{\mathrm{exc}}^{+}$ levels have demonstrated that a $\Lambda -{\Sigma }^0$ mixing CSB model due to Dalitz and von Hippel (1964) is capable of reproducing this large value of $\Delta B_{\Lambda }^{J=0}$. These calculations are discussed here with emphasis placed on the leading-order chiral EFT hyperon-nucleon strong-interaction Bonn-Juelich potential model used and the no-core shell-model calculational scheme applied. The role of one-pion exchange in producing sizable CSB level splittings in the $A=4$ mirror hypernuclei is discussed.

   ↳ nucl-thhep-phnucl-exNPA(2016)·40 citations
6. 06*

   The interaction region of high energy protons

   I.M. Dremin🇷🇺 · S.N. White🇨🇭

   The spatial view of the interaction region of colliding high energy protons (in terms of impact parameter) is considered. It is shown that the region of inelastic collisions has a very peculiar shape. It saturates for central collisions at an energy of 7 TeV. We speculate on the further evolution with energy, which is contrasted to the "black disk" picture.

   ↳ hep-phhep-exnucl-exnucl-th9 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.