Mon·Jan 18, 2016Monday·January 18, 2016

1. 01*

   Examination of experimental conditions for the production of proton-rich and neutron-rich hypernuclei

   C. Rappold🇩🇪 · J. F. López Fidalgo🇪🇸

   After the demonstration of the feasibility of hypernuclear spectroscopy with heavy-ion beams, the HypHI Collaboration will next focus on the study of proton- and neutron-rich hypernuclei. The use of a fragment separator for the production and separation of rare isotope beams is a crucial aspect to producing hypernuclei far from the stability line. Precise spectroscopy of exotic hypernuclei is planned to be carried out at the GSI and later at the FAIR facility with the FRS and Super-FRS fragment separators. A systematic study and an optimization analysis were performed in order to determine optimal experimental conditions for producing hypernuclei with high isospin. The optimal conditions are obtained based on theoretical models for the heavy-ion induced reaction and hypernuclei production. Experimental efficiencies for the production of exotic secondary beams were also taken into account via Monte Carlo simulations of the fragment separator. The developed methodology is presented to deduce the expected yields of ${}_{\Lambda }^8$Be and subsequently other proton-rich and neutron-rich hypernuclei.

   nucl-exPRC(2016)·21 citations
2. 02*

   Beta decay of the exotic $T_z$ = -2 nuclei ${}^{48}$Fe, ${}^{52}$Ni and ${}^{56}$Zn

   S.E.A. Orrigo🇪🇸 · B. Rubio🇪🇸 · Y. Fujita🇯🇵 · W. Gelletly🇬🇧 · J. Agramunt🇪🇸 · A. Algora🇪🇸 · P. Ascher🇫🇷 · B. Bilgier🇹🇷 · B. Blank🇫🇷 · L. Cáceres🇫🇷 · R.B. Cakirli🇹🇷 · E. Ganioğlu🇹🇷 and 15 other authors

   The results of a study of the beta decays of three proton-rich nuclei with $T_z=\text{-}2$, namely ${}^{48}$Fe, ${}^{52}$Ni and ${}^{56}$Zn, produced in an experiment carried out at GANIL, are reported. In all three cases we have extracted the half-lives and the total $\beta$-delayed proton emission branching ratios. We have measured the individual $\beta$-delayed protons and $\beta$-delayed $\gamma$ rays and the branching ratios of the corresponding levels. Decay schemes have been determined for the three nuclei, and new energy levels are identified in the daughter nuclei. Competition between $\beta$-delayed protons and $\gamma$ rays is observed in the de-excitation of the $T=2$ Isobaric Analogue States in all three cases. Absolute Fermi and Gamow-Teller transition strengths have been determined. The mass excesses of the nuclei under study have been deduced. In addition, we discuss in detail the data analysis taking as a test case ${}^{56}$Zn, where the exotic $\beta$-delayed $\gamma$-proton decay has been observed.

   nucl-exPRC(2016)·37 citations
3. 03*

   Coulomb breakup of neutron-rich ${}^{29,30}$Na isotopes near the island of inversion

   A . Rahaman · Ushasi Datta · T. Aumann · S. Beceiro-Novo · K. Boretzky · C. Caesar · B.V. Carlson · W.N. Catford · S. Chakraborty · M. Chartier · D. Cortina-Gil · G. De. Angelis and 41 other authors

   First results are reported on the ground state configurations of the neutron-rich ${}^{29,30}$Na isotopes, obtained via Coulomb dissociation (CD) measurements as a method of the direct probe. The invariant mass spectra of those nuclei have been obtained through measurement of the four-momentum of all decay products after Coulomb excitation on a ${}^{208}Pb$ target at energies of 400-430 MeV/nucleon using FRS-ALADIN-LAND setup at GSI, Darmstadt. Integrated Coulomb-dissociation cross-sections (CD) of 89 $(7)$ mb and 167 $(13)$ mb up to excitation energy of 10 MeV for one neutron removal from ${}^{29}$Na and ${}^{30}$Na respectively, have been extracted. The major part of one neutron removal, CD cross-sections of those nuclei populate core, in its' ground state. A comparison with the direct breakup model, suggests the predominant occupation of the valence neutron in the ground state of ${}^{29}$Na$(3/2^{+})$ and ${}^{30}$Na$(2^{+})$ is the $d$ orbital with small contribution in the $s$-orbital which are coupled with ground state of the core. The ground state configurations of these nuclei are as ${}^{28}$Na_{gs (1^+)\otimes\nu_{s,d} and ${}^{29}$Na${}_{gs}(3/2^{+})\otimes {\nu }_{s,d}$, respectively. The ground state spin and parity of these nuclei, obtained from this experiment are in agreement with earlier reported values. The spectroscopic factors for the valence neutron occupying the $s$ and $d$ orbitals for these nuclei in the ground state have been extracted and reported for the first time. A comparison of the experimental findings with the shell model calculation using MCSM suggests a lower limit of around 4.3 MeV of the sd-pf shell gap in ${}^{30}$Na.

   nucl-exnucl-thJ.Phys.G(2017)·7 citations
4. 04*

   Sensitivity of the COSY Dibaryon Candidate to np Elastic Scattering Measurements

   R.L. Workman🇺🇸 · W.J. Briscoe🇺🇸 · I.I. Strakovsky (GWU)🇺🇸

   The case for a dibaryon resonance, appearing in np scattering, has support from a WASA-at-COSY measurement of the polarization quantity A_y over a center-of-mass energy region suggested by structures seen earlier in two-pion production experiments. Here we compare fits with and without an associated pole in order to clarify the impact of these COSY data. We then consider what further np scattering measurements would most clearly distinguish between the pole and non-pole fit results.

   ↳ nucl-thhep-exhep-phnucl-exPRC(2016)·20 citations
5. 05*

   Unified ab initio approaches to nuclear structure and reactions

   Petr Navratil🇨🇦 · Sofia Quaglioni🇺🇸 · Guillaume Hupin🇫🇷 · Carolina Romero-Redondo🇺🇸 · Angelo Calci🇨🇦

   The description of nuclei starting from the constituent nucleons and the realistic interactions among them has been a long-standing goal in nuclear physics. In addition to the complex nature of the nuclear forces, with two-, three- and possibly higher many-nucleon components, one faces the quantum-mechanical many-nucleon problem governed by an interplay between bound and continuum states. In recent years, significant progress has been made in ab initio nuclear structure and reaction calculations based on input from QCD-employing Hamiltonians constructed within chiral effective field theory. After a brief overview of the field, we focus on ab initio many-body approaches - built upon the No-Core Shell Model - that are capable of simultaneously describing both bound and scattering nuclear states, and present results for resonances in light nuclei, reactions important for astrophysics and fusion research. In particular, we review recent calculations of resonances in the ${}^6$He halo nucleus, of five- and six-nucleon scattering, and an investigation of the role of chiral three-nucleon interactions in the structure of ${}^9$Be. Further, we discuss applications to the ${}^7$Be$(p,\gamma {)}^8$B radiative capture. Finally, we highlight our efforts to describe transfer reactions including the ${}^3$H$(d,n{)}^4$He fusion.

   ↳ nucl-thastro-ph.SRnucl-exPhys.Scripta(2016)·235 citations
6. 06*

   The Majorana Demonstrator Radioassay Program

   N. Abgrall🇺🇸 · I.J. Arnquist🇺🇸 · F.T. Avignone III🇺🇸 · H.O. Back🇺🇸 · A.S. Barabash🇷🇺 · F.E. Bertrand🇺🇸 · M. Boswell🇺🇸 · A.W. Bradley🇺🇸 · V. Brudanin🇷🇺 · M. Busch🇺🇸 · M. Buuck🇺🇸 · D. Byram🇺🇸 and 73 other authors

   The MAJORANA collaboration is constructing the MAJORANA DEMONSTATOR at the Sanford Underground Research Facility at the Homestake gold mine, in Lead, SD. The apparatus will use Ge detectors, enriched in isotope \nuc{76}{Ge}, to demonstrate the feasibility of a large-scale Ge detector experiment to search for neutrinoless double beta decay. The long half-life of this postulated process requires that the apparatus be extremely low in radioactive isotopes whose decays may produce backgrounds to the search. The radioassay program conducted by the collaboration to ensure that the materials comprising the apparatus are sufficiently pure is described. The resulting measurements of the radioactive-isotope contamination for a number of materials studied for use in the detector are reported.

   ↳ physics.ins-dethep-exnucl-exNucl.Instrum.Meth.A(2016)·136 citations
7. 07*

   Ultra-fast timing detectors to probe exotic properties of nuclei using RIB facility

   Ushasi Datta🇮🇳 · S. Chakraborty🇮🇳 · A. Rahaman (Saha Institute of Nuclear Physics, India)🇮🇳

   Recently, the facilities of radioactive ion beam (RIB) combined with advanced detector systems provide us unique opportunity to probe the exotic properties of the nuclei with unusual neutron-to-proton ratio. In this article, a study of characterization of different types of ultra-fast timing detectors: a special type of gas detector (multi-strip multi-gap resistive plate chamber, MMRPC) ($\sigma$ $<$100 ps), scintillators array ( viz., $LaB{r}_3:Ce$) (timing resolution ($\sigma <$250 ps) are being presented. A brief discussion on usage of these different types of ultra-fast timing detector systems at radioactive ion beam facilities is also included.

   ↳ physics.ins-detnucl-ex0 citations
8. 08*

   What can we learn from the directed flow in heavy-ion collisions at BES RHIC energies?

   Yu. B. Ivanov🇷🇺 · A. A. Soldatov🇷🇺

   Analysis of directed flow ($v_1$) of protons, antiprotons and pions in heavy-ion collisions is performed in the range of collision energies $\sqrt{s_{NN}}$ = 2.7--39 GeV. Simulations have been done within a three-fluid model employing a purely hadronic equation of state (EoS) and two versions of the EoS with deconfinement transitions: a first-order phase transition and a smooth crossover transition. The crossover EoS is unambiguously preferable for the description of the most part of experimental data in this energy range. The directed flow indicates that the crossover deconfinement transition takes place in semicentral Au+Au collisions in a wide range of collision energies 4 \lsim\sqrt{s_{NN}}\lsim$ 30 GeV. The obtained results suggest that the deconfinement EoS's in the quark-gluon sector should be stiffer at high baryon densities than those used in the calculation. The latter finding is in agreement with that discussed in astrophysics.

   ↳ nucl-thhep-phnucl-exEPJA(2016)·35 citations
9. 09*

   Initial conditions from the shadowed Glauber model for Pb+Pb at $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV

   Snigdha Ghosh🇮🇳 · Sushant K. Singh🇮🇳 · Sandeep Chatterjee🇮🇳 · Jane Alam🇮🇳 · Sourav Sarkar🇮🇳

   We study the initial conditions for Pb+Pb collisions at $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV using the two component Monte-Carlo Glauber model with shadowing of the nucleons in the interior by the leading ones. The model parameters are fixed by comparing to the multiplicity data of p+Pb and Pb+Pb at $\sqrt{s_{\mathrm{NN}}}=5.02$ and $2.76$ TeV respectively. We then compute the centrality dependence of the eccentricities upto the fourth order as well as their event by event distributions. The inclusion of shadowing brings the Monte-Carlo Glauber model predictions in agreement with data as well as with results from other dynamical models of initial conditions based on gluon saturation at high energy nuclear collisions. Further, we find that the shadowed Glauber model provides the desired relative magnitude between the ellipticity and triangularity of the initial energy distribution required to explain the data on the even and odd flow harmonics $v_2$ and $v_3$ respectively at the LHC.

   ↳ nucl-thhep-phnucl-exPRC(2016)·14 citations
10. 10*

    CERN antiproton target: hydrocode analysis of its core material dynamic response under proton beam impact

    Claudio Torregrosa Martin🇨🇭 · Antonio Perillo-Marcone🇨🇭 · Marco Calviani🇨🇭 · José-Luis Muñoz-Cobo🇪🇸

    Antiprotons are produced at CERN by colliding a 26 GeV/c proton beam with a fixed target made of a 3 mm diameter, 55 mm length iridium core. The inherent characteristics of antiproton production involve extremely high energy depositions inside the target when impacted by each primary proton beam, making it one of the most dynamically demanding among high energy solid targets in the world, with a rise temperature above 2000 {\deg}C after each pulse impact and successive dynamic pressure waves of the order of GPa's. An optimized redesign of the current target is foreseen for the next 20 years of operation. As a first step in the design procedure, this numerical study delves into the fundamental phenomena present in the target material core under proton pulse impact and subsequent pressure wave propagation by the use of hydrocodes. Three major phenomena have been identified, (i) the dominance of a high frequency radial wave which produces destructive compressive-to-tensile pressure response (ii) The existence of end-of-pulse tensile waves and its relevance on the overall response (iii) A reduction of 40% in tensile pressure could be obtained by the use of a high density tantalum cladding.

    ↳ physics.ins-detnucl-exphysics.acc-phPhys.Rev.ST Accel.Beams(2016)·10 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.