Wed·Oct 29, 2014Wednesday·October 29, 2014

1. 01*

   Measurement of the Shape Factor for the Beta Decay of ${}^{14}$O

   E.A. George🇺🇸 · P.A. Voytas🇺🇸 · G.W. Severin🇺🇸 · L.D. Knutson🇺🇸

   We report results from an experiment designed to test the conserved vector current (CVC) hypothesis by measuring the shape of the $\beta$-decay spectrum for the allowed $0^{+}\to 1^{+}$ ground state decay of ${}^{14}$O. Measurements of the spectrum intensity were obtained with a superconducting beta spectrometer and will be reported for positron kinetic energies ranging from 1.9 to 4.0 MeV. After dividing out phase space, Coulomb, and other correction factors, the resulting shape function has a negative slope of several per cent per MeV. We define a parameter $a^{\prime }$, which is essentially a measure of the average slope of the shape function over the energy range of the measurements, and determine its value to be $a^{\prime }=-0.0290\pm 0.0008$ (stat.) $\pm 0.0006$ (syst.). The measured slope parameter is in good agreement with predictions from shell model calculations that respect CVC.

   nucl-exphysics.ins-detPRC(2014)·12 citations
2. 02*

   Production of $\eta$ and ${\eta }^{\prime }$ Mesons on Nucleons and Nuclei

   B. Krusche🇨🇭 · C. Wilkin🇬🇧

   The production of $\eta$ and ${\eta }^{\prime }$ mesons in photon- and hadron-induced reactions on free and quasi-free nucleons and on nuclei is reviewed. The extensive database on $\gamma N\to \eta N$, for both proton and neutron targets, is described in detail and its implications for the search for $N^{\star }$ resonances much heavier than the dominant $S_{11}(1535)$ discussed. Though less is currently known about the production of the ${\eta }^{\prime }$ or of $\eta \pi$ pairs, these also offer tantalizing prospects in the search for the missing isobars. The more limited data available on pion-induced production are still necessary ingredients in the partial wave analysis discussed. The production of the $\eta$-meson in $pp$ and $pn$ collisions shows once again the strong influence of the $S_{11}(1535)$ isobar, which is in contrast to the relatively weak behaviour seen near threshold for ${\eta }^{\prime }$ production. This difference is reflected in the important final state interaction effects of the $\eta$ in nuclei that may even lead to this meson being "bound" in some systems. The evidence for this is reviewed for both $\gamma A$ and $pA$ collisions. The inclusive photoproduction of $\eta$, ${\eta }^{\prime }$, and $\eta \pi$ pairs from nuclei provides further information regarding the production mechanism and the interaction of the $\eta$ and ${\eta }^{\prime }$ with nuclei and the $\eta \pi$ pairs may even allow access to low mass $\eta A$ systems that are forbidden in direct single-meson photoproduction.

   nucl-exPPNP(2015)·77 citations
3. 03*

   Alpha clusters and collective flow in ultra-relativistic carbon - heavy nucleus collisions

   Piotr Bozek🇵🇱 · Wojciech Broniowski🇵🇱 · Enrique Ruiz Arriola🇪🇸 · Maciej Rybczynski🇵🇱

   We investigate ultrarelativistic collisions of the 12C nucleus with heavy targets and show that the harmonic flow measures based on ratios of cumulant moments are particularly suited to study the intrinsic deformation of the 12C wave function. That way one can probe the expected alpha clusterization in the ground state, which leads to large initial triangularity in the shape of the fireball in the transverse plane. We show that the clusterization effect results in very characteristic behavior of the ratios of the cumulant moments as functions of the number of participant nucleons, both for the elliptic and triangular deformations. Thus the experimental event-by-event studies of harmonic flow in ultrarelativistic light-heavy collisions may offer a new window to look at the ground-state structure of light nuclei.

   ↳ nucl-thnucl-exPRC(2014)·52 citations
4. 04*

   Structure of hypernuclei in relativistic approaches

   K. Hagino🇯🇵 · J.M. Yao🇯🇵

   We review the relativistic mean-field approach to various aspects of hypernuclei. It was Brockmann and Weise who first applied this approach to hypernuclei. At that time, it had been already observed experimentally that the spin-orbit splittings in hypernuclei are significantly smaller than that in ordinary nuclei. The relativistic approach was suitable for a discussion of spin-orbit splittings in hypernuclei, as the spin-orbit interaction is naturally emerged with the relativistic framework. Since this seminal work, many developments have been done and the relativistic approach has been applied both to the ground state and to excited states of hypernuclei. We summarize those developments in the Chapter. We shall concentrate on $\Lambda$-hypernuclei and do not discuss $\Sigma$ hypernuclei, since the theoretical treatment is rather similar to each other.

   ↳ nucl-thnucl-exInt.Rev.Nucl.Phys.(2016)·14 citations
5. 05*

   Charmonium production in $\bar{p}$-induced reactions on nuclei

   Alexei Larionov🇩🇪 · Marcus Bleicher🇩🇪 · Albrecht Gillitzer🇩🇪 · Mark Strikman🇺🇸

   The production of charmonia in the antiproton-nucleus reactions at $p_{\mathrm{lab}}=3-10$ GeV/c is studied within the Glauber model and the generalized eikonal approximation. The main reaction channel is charmonium formation in an antiproton-proton collision. The target mass dependence of the charmonium transparency ratio allows to determine the charmonium-nucleon cross section. The polarization effects in the production of ${\chi }_{c2}$ states are evaluated.

   ↳ nucl-thhep-phnucl-exEPJ Web Conf.(2014)·0 citations
6. 06*

   Antiproton-nucleus reactions at intermediate energies

   A. B. Larionov🇩🇪

   Antiproton-induced reactions on nuclei at the beam energies from hundreds MeV up to several GeV provide an excellent opportunity to study interactions of the antiproton and secondary particles (mesons, baryons and antibaryons) with nucleons. Antiproton projectile is unique in the sense that most of annihilation particles are relatively slow in the target nucleus frame. Hence, the prehadronic effects do not much influence their interactions with the nucleons of the nuclear residue. Moreover, the particles with momenta less than about 1 GeV/c are sensitive to the nuclear mean field potentials. This paper discusses the microscopic transport calculations of the antiproton-nucleus reactions and is focused on three related problems: (i) the antiproton potential determination, (ii) possible formation of strongly bound antiproton-nucleus systems, and (iii) strangeness production.

   ↳ nucl-thhep-phnucl-exNucl.Sci.Tech.(2015)·4 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.