Mon·Sep 19, 2011Monday·September 19, 2011

1. 01*

   First Use of High Charge States for Mass Measurements of Short-lived Nuclides in a Penning Trap

   S. Ettenauer🇨🇦 · M. C. Simon🇨🇦 · A. T. Gallant🇨🇦 · T. Brunner🇨🇦 · U. Chowdhury🇨🇦 · V. V. Simon🇨🇦 · M. Brodeur🇨🇦 · A. Chaudhuri🇨🇦 · E. Mané🇨🇦 · C. Andreoiu🇨🇦 · G. Audi🇫🇷 · J. R. Crespo López-Urrutia🇩🇪 and 8 other authors

   Penning trap mass measurements of short-lived nuclides have been performed for the first time with highly-charged ions (HCI), using the TITAN facility at TRIUMF. Compared to singly-charged ions, this provides an improvement in experimental precision that scales with the charge state q. Neutron-deficient Rb-isotopes have been charge bred in an electron beam ion trap to q = 8 - 12+ prior to injection into the Penning trap. In combination with the Ramsey excitation scheme, this unique setup creating low energy, highly-charged ions at a radioactive beam facility opens the door to unrivalled precision with gains of 1-2 orders of magnitude. The method is particularly suited for short-lived nuclides such as the superallowed {\beta} emitter 74Rb (T1/2 = 65 ms). The determination of its atomic mass and an improved QEC-value are presented.

   nucl-exphysics.atom-phPRL(2011)·54 citations
2. 02*

   Hypernuclei Production by K- at rest

   G. Bonomi🇮🇹

   The creation of a hypernucleus requires the injection of strangeness into the nucleus. This is possible in different ways, mainly using pi+ or K- beams on fixed targets. A review of hypernuclei production by K- at rest is here presented. When a K- stops inside a nucleus it can undergo the so called "strangeness-exchange reaction", in which a neutron is replaced by a Lambda with the emission of a pion. By precisely studying the outgoing pions both the binding energy and the formation probability of the hypernuclei can be measured. New measurements from the FINUDA experiment on 7Li, 9Be, 13C and 16O, coupled with previous measurements on 12C and 16O, allowed for the first time the study of the formation of hypernuclei as a function of the atomic mass number A. The new measurements also offered the possibility of disentangling the effects due to atomic wave-function of the captured K- from those due to the pion optical nuclear potential and from those due to the specific hypernuclear states. These new results on the study of the hypernuclei production by K- at rest are here presented and discussed.

   nucl-ex1 citation
3. 03*

   The SPS ion program and the first LHC data

   M. Gazdzicki🇩🇪

   For the first time in the CERN history two experimental programs devoted to study nucleus-nucleus collisions at high energies are performed in parallel. In the SPS ion program, carried out by NA61/SHINE, interactions of light and medium size ions in the energy range 5-20 GeV are investigated. The program aims to discover the critical point of strongly interacting matter as well as establish properties of the onset of deconfinement. In 2010 ALICE, ATLAS and CMS at LHC recorded first data on Pb+Pb collisions at the highest energy reached up to now, 2760 GeV. This opens a new exciting area in the field of heavy ion collisions. The relation between the two programs is discussed in this presentation. Surprisingly, the first LHC results strongly support the NA49 discovery of the onset of deconfinement and thus further experimental study of nucleus-nucleus collisions at the CERN SPS.

   nucl-exhep-phAIP Conf.Proc.(2012)·0 citations
4. 04*

   Role of Sterile Neutrino Warm Dark Matter in Rhenium and Tritium Beta Decays

   H. J. de Vega🇫🇷 · O. Moreno🇪🇸 · E. Moya de Guerra🇪🇸 · M. Ramon Medrano🇪🇸 · N. Sanchez🇫🇷

   Sterile neutrinos with mass in the range of one to a few keV are important as extensions of the Standard Model of particle physics and are serious dark matter (DM) candidates. This DM mass scale (warm DM) is in agreement with both cosmological and galactic observations. We study the role of a keV sterile neutrino through its mixing with a light active neutrino in Rhenium 187 and Tritium beta decays. We pinpoint the energy spectrum of the beta particle, 0 < T_e < (Q_{beta} - m_s), as the region where a sterile neutrino could be detected and where its mass m_s could be measured. This energy region is at least 1 keV away rom the region suitable to measure the mass of the light active neutrino, located near the endpoint Q_{beta} . The emission of a keV sterile neutrino in a beta decay could show up as a small kink in the spectrum of the emitted beta particle. With this in view, we perform a careful calculation of the Rhenium and Tritium beta spectra and estimate the size of this perturbation by means of the dimensionless ratio R of the sterile neutrino to the active neutrino contributions. We comment on the possibility of searching for sterile neutrino signatures in two experiments which are currently running at present, MARE and KATRIN, focused on the Rhenium 187 and Tritium beta decays respectively.

   ↳ hep-phastro-ph.COnucl-exnucl-thNPB(2013)·60 citations
5. 05*

   Commentary on rainbow-ladder truncation for excited states and exotics

   Si-xue Qin🇨🇳 · Lei Chang🇺🇸 · Yu-xin Liu🇨🇳 · Craig D. Roberts🇺🇸 · David J. Wilson🇺🇸

   Ground-state, radially-excited and exotic scalar-, vector- and flavoured-pseudoscalar-mesons are studied in rainbow-ladder truncation using an interaction kernel that is consonant with modern DSE- and lattice-QCD results. The inability of this truncation to provide realistic predictions for the masses of excited- and exotic-states is confirmed and explained. On the other hand, its application does provide information that is potentially useful in proceeding beyond this leading-order truncation, e.g.: assisting with development of projection techniques that ease the computation of excited state properties; placing qualitative constraints on the long-range behaviour of the interaction kernel; and highlighting and illustrating some features of hadron observables that do not depend on details of the dynamics.

   ↳ nucl-thhep-lathep-phnucl-exPRC(2012)·165 citations
6. 06*

   EMC effect, short-range nuclear correlations, neutron stars

   Mark Strikman (Penn State University)🇺🇸

   The recent x>1 (e,e') and correlation experiments at momentum transfer Q^2 \ge 2 GeV^2 confirm presence of short-range correlations (SRC) in nuclei mostly build of nucleons. Recently we evaluated in a model independent way the dominant photon contribution to the nuclear structure. Taking into account this effect and using definition of x consistent with the exact kinematics of eA scattering (with exact sum rules) results in the significant reduction of R_A(x,Q^2)=F_{2A}(x,Q^2)/F_{2N}(x,Q^2) ratio which explains \sim 50% of the EMC effect for x\le 0.55 where Fermi motion effects are small. The remaining part of the EMC effect at $x\ge 0.5$ is consistent with dominance of the contribution of SRCs. Implications for extraction of the F_{2n}/F_{2p} ratio are discussed. Smallness of the non-nucleonic degrees of freedom in nuclei matches well the recent observation of a two-solar mass neutron star, and while large pn SRCs lead to enhancement of the neutron star cooling rate for kT\le 0.01 MeV.

   ↳ nucl-thnucl-exAIP Conf.Proc.(2012)·0 citations
7. 07*

   Two-photon exchange and elastic scattering of longitudinally polarized electron on polarized deuteron

   Alexander P.Kobushkin🇺🇦 · Yaroslav D.Krivenko-Emetov🇺🇦 · Stanislav Dubnicka🇸🇰 · Anna Z.Dubnickova🇸🇰

   Structure functions and polarization observables in elastic scattering of longitudinally polarized electron on polarized deuteron are considered within approximation of one-photon + two-photon exchange. It is shown that contribution of two-photon exchange in the generalized structure function A is of order of few percent, while in the generalized structure function B it is of order of 10--20 %. We have found that components T_{20} and T_{21} of tensor analyzing power are mainly determined by one-photon exchange, but T_{22} is mainly determined by interference between one-photon exchange and two-photon exchange. We have also considered polarization observables T_{11}, C_{21} and C_{22} which are proportional to imaginary part of the reaction amplitude and vanish in the framework of one-photon exchange.

   ↳ nucl-thhep-exhep-phnucl-exPRC(2011)·7 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.