Tue·May 5, 2015Tuesday·May 5, 2015

1. 01*

   The ${}^{136}$Xe + ${}^{208}$Pb reaction: A test of models of multi-nucleon transfer reactions

   J. S. Barrett🇺🇸 · R. Yanez🇺🇸 · W. Loveland🇺🇸 · S. Zhu🇺🇸 · A. D. Ayangeakaa🇺🇸 · M. P. Carpenter🇺🇸 · J. P. Greene🇺🇸 · R. V. F. Janssens🇺🇸 · T. Lauritsen🇺🇸 · E. A. McCutchan🇺🇸 · A. A. Sonzogni🇺🇸 · C. J. Chiara🇺🇸 · J. L. Harker🇺🇸 · W. B. Walters🇺🇸

   The yields of over 200 projectile-like fragments (PLFs) and target-like fragments (TLFs) from the interaction of (E${}_{c.m.}$=450 MeV) ${}^{136}$Xe with a thick target of ${}^{208}$Pb were measured using Gammasphere and off-line $\gamma$-ray spectroscopy, giving a comprehensive picture of the production cross sections in this reaction.The measured yields were compared to predictions of the GRAZING model and the predictions of Zagrebaev and Greiner using a quantitative metric, the theory evaluation factor, {\bf tef}. The GRAZING model predictions are adequate for describing the yields of nuclei near the target or projectile but grossly underestimate the yields of all other products. The predictions of Zagrebaev and Greiner correctly describe the magnitude and maxima of the observed TLF transfer cross sections for a wide range of transfers ($\Delta$Z = -8 to $\Delta$Z = +2). However for $\Delta$Z =+4, the observed position of the maximum in the distribution is four neutrons richer than the predicted maximum. The predicted yields of the neutron-rich N=126 nuclei exceed the measured values by two orders of magnitude. Correlations between TLF and PLF yields are discussed.

   nucl-exPRC(2015)·122 citations
2. 02*

   First application of the Trojan Horse Method with a Radioactive Ion Beam: study of the ${}^{18}$F($p,\alpha$)${}^{15}$O}} reaction at astrophysical energies

   S. Cherubini🇮🇹 · M. Gulino🇮🇹 · C. Spitaleri🇮🇹 · G.G. Rapisarda🇮🇹 · M. La Cognata🇮🇹 · L. Lamia🇮🇹 · R.G. Pizzone🇮🇹 · S. Romano🇮🇹 · S. Kubono🇨🇳 · H. Yamaguchi🇯🇵 · S. Hayakawa🇮🇹 · Y. Wakabayashi🇯🇵 and 10 other authors

   Measurement of nuclear cross sections at astrophysical energies involving unstable species is one of the most challenging tasks in experimental nuclear physics. The use of indirect methods is often unavoidable in this scenario. In this paper the Trojan Horse Method is applied for the first time to a radioactive ion beam induced reaction studying the ${}^{18}$F($p,\alpha$)${}^{15}$O process at low energies relevant to astrophysics via the three body reaction ${}^2$H(${}^{18}$F,${\alpha }^{15}$O)n. The knowledge of the ${}^{18}$F($p,\alpha$)${}^{15}$O reaction rate is crucial to understand the nova explosion phenomena. The cross section of this reaction is characterized by the presence of several resonances in ${}^{19}$Ne and possibly interference effects among them. The results reported in Literature are not satisfactory and new investigations of the ${}^{18}$F($p,\alpha$)${}^{15}$O reaction cross section will be useful. In the present work the spin-parity assignments of relevant levels have been discussed and the astrophysical S-factor has been extracted considering also interference effects

   nucl-exPRC(2015)·83 citations
3. 03*

   Measurement of charm and beauty production at central rapidity versus charged-particle multiplicity in proton-proton collisions at $\sqrt{\text{s}}=7$ TeV

   ALICE Collaboration

   Prompt D meson and non-prompt J/$\psi$ yields are studied as a function of the multiplicity of charged particles produced in inelastic proton-proton collisions at a centre-of-mass energy of $\sqrt{s}=7$ TeV. The results are reported as a ratio between yields in a given multiplicity interval normalised to the multiplicity-integrated ones (relative yields). They are shown as a function of the multiplicity of charged particles normalised to the average value for inelastic collisions (relative charged-particle multiplicity). D${}^0$, D${}^{+}$ and D${}^{\ast +}$ mesons are measured in five $p_{\mathrm{T}}$ intervals from 1 to 20 GeV/$c$ and for $|y|<0.5$ via their hadronic decays. The D-meson relative yield is found to increase with increasing charged-particle multiplicity. For events with multiplicity six times higher than the average multiplicity of inelastic collisions, a yield enhancement of a factor about 15 relative to the multiplicity-integrated yield in inelastic collisions is observed. The yield enhancement is independent of transverse momentum within the uncertainties of the measurement. The D${}^0$-meson relative yield is also measured as a function of the relative multiplicity at forward pseudorapidity. The non-prompt J/$\psi$, i.e. the B hadron, contribution to the inclusive J/$\psi$ production is measured in the di-electron decay channel at central rapidity. It is evaluated for $p_{\mathrm{T}}>1.3$ GeV/$c$ and $|y|<0.9$, and extrapolated to $p_{\mathrm{T}}>0$. The fraction of non-prompt J/$\psi$ in the inclusive J/$\psi$ yields shows no dependence on the charged-particle multiplicity at central rapidity. Charm and beauty hadron relative yields exhibit a similar increase with increasing charged-particle multiplicity. The measurements are compared to PYTHIA 8, EPOS 3 and percolation calculations.

   nucl-exhep-exJHEP(2015)·175 citations
4. 04*

   Energy and Centrality dependence of $d{N}_{\mathrm{ch}}/d\eta$ and $d{E}_{\mathrm{T}}/d\eta$ in Heavy-Ion Collisions from $\sqrt{s_{\mathrm{NN}}}$ =7.7 GeV to 5.02 TeV

   Aditya Nath Mishra🇮🇳 · Raghunath Sahoo🇮🇳 · Pragati Sahoo🇮🇳 · Pooja Pareek🇮🇳 · Nirbhay K. Behera🇮🇳 · Basanta K. Nandi🇮🇳

   The centrality dependence of pseudorapidity density of charged particles and transverse energy is studied for a wide range of collision energies for heavy-ion collisions at midrapidity from 7.7 GeV to 5.02 TeV. A two-component model approach has been adopted to quantify the soft and hard components of particle production, coming from nucleon participants and binary nucleon-nucleon collisions, respectively. Within experimental uncertainties, the hard component contributing to the particle production has been found not to show any clear collision energy dependence from RHIC to LHC. The effect of centrality and collision energy in particle production seem to factor out with some degree of dependency on the collision species. The collision of Uranium-like deformed nuclei opens up new challenges in understanding the energy-centrality factorization, which is evident from the centrality dependence of transverse energy density, when compared to collision of symmetric nuclei.

   ↳ hep-phhep-exnucl-exEPJA(2016)·7 citations
5. 05*

   Can a many-nucleon structure be visible in bremsstrahlung emission during $\alpha$ decay?

   Sergei P. Maydanyuk (1 and 2)🇺🇦 · Peng-Ming Zhang (1)🇨🇳 · Li-Ping Zou (1) ((1) Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China, (2) Institute for Nuclear Research, National Academy of Sciences of Ukraine, Kiev, Ukraine)🇨🇳

   We analyze if the nucleon structure of the $\alpha$ decaying nucleus can be visible in the experimental bremsstrahlung spectra of the emitted photons which accompany such a decay. We develop a new formalism of the bremsstrahlung model taking into account distribution of nucleons in the $\alpha$ decaying nuclear system. We conclude the following: (1) After inclusion of the nucleon structure into the model the calculated bremsstrahlung spectrum is changed very slowly for a majority of the $\alpha$ decaying nuclei. However, we have observed that visible changes really exist for the ${}^{106}\mathrm{Te}$ nucleus ($Q_{\alpha }=4.29$ MeV, $T_{1/2}$=70 mks) even for the energy of the emitted photons up to 1 MeV. This nucleus is a good candidate for future experimental study of this task. (2) Inclusion of the nucleon structure into the model increases the bremsstrahlung probability of the emitted photons. (3) We find the following tendencies for obtaining the nuclei, which have bremsstrahlung spectra more sensitive to the nucleon structure: (a) direction to nuclei with smaller $Z$, (b) direction to nuclei with larger $Q_{\alpha }$-values.

   ↳ nucl-thhep-phnucl-ex5 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.