Wed·Aug 8, 2018Wednesday·August 8, 2018

1. 01*

   Studies of the Giant Dipole Resonance in ${}^{27}$Al, ${}^{40}$Ca, ${}^{56}$Fe, ${}^{58}$Ni and ${}^{208}$Pb with high energy-resolution inelastic proton scattering under 0${}^{\circ }$

   M. Jingo (1,2)🇿🇦 · E.Z. Buthelezi (3)🇿🇦 · J. Carter (1) · G.R.J. Cooper (4)🇿🇦 · R.W. Fearick (5)🇿🇦 · S.V. Förtsch (3)🇿🇦 · C.O. Kureba (1)🇿🇦 · A.M. Krumbholz (6) · P. von Neumann-Cosel (6)🇩🇪 · R. Neveling (3) · P. Papka (7)🇿🇦 · I. Poltoratska (6) and 7 other authors

   A survey of the fine structure of the Isovector Giant Dipole Resonance (IVGDR) was performed, using the recently commissioned zero-degree facility of the K600 magnetic spectrometer at iThemba LABS. Inelastic proton scattering at an incident energy of 200 MeV was measured on ${}^{27}$Al, ${}^{40}$Ca, ${}^{56}$Fe, ${}^{58}$Ni and ${}^{208}$Pb. A high energy resolution ($\mathrm{\Delta }E\simeq$ 40 keV FWHM) could be achieved after utilising faint-beam and dispersion-matching techniques. Considerable fine structure is observed in the energy region of the IVGDR and characteristic energy scales are extracted from the experimental data by means of a wavelet analysis. The comparison with Quasiparticle-Phonon Model (QPM) calculations provides insight into the relevance of different giant resonance decay mechanisms. Photoabsorption cross sections derived from the data assuming dominance of relativistic Coulomb excitation are in fair agreement with previous work using real photons.

   nucl-exnucl-thEPJA(2018)·16 citations
2. 02*

   Double beta decay of ${}^{150}$Nd to the first excited $0^{+}$ level of ${}^{150}$Sm: preliminary results

   A.S. Barabash🇷🇺 · P. Belli🇮🇹 · R. Bernabei🇮🇹 · R.S. Boiko🇺🇦 · F. Cappella🇮🇹 · V. Caracciolo🇮🇹 · R. Cerulli🇮🇹 · F.A. Danevich🇺🇦 · A. Di Marco🇮🇹 · A. Incicchitti🇮🇹 · D.V. Kasperovych🇺🇦 · R.V. Kobychev🇺🇦 and 7 other authors

   The double beta decay of ${}^{150}$Nd to the first excited 0${}^{+}$ level of ${}^{150}$Sm ($E_{exc}$ = 740.5 keV) has been investigated with the help of the ultra-low-background setup consisting of four HP Ge (high-purity germanium) detectors ($\approx$ 225 cm${}^3$ volume each one) at the Gran Sasso underground laboratory of INFN (Italy). A highly purified 2.381-kg sample of neodymium oxide (Nd${}_2$O${}_3$) was used as a source of $\gamma$ quanta expected in the decays. Gamma quanta with energies 334.0 keV and 406.5 keV emitted after deexcitation of the $0_1^{+}$ 740.5 keV level of ${}^{150}$Sm are observed in the coincidence spectra accumulated over 16375 h. The half-life relatively to the two neutrino double beta decay ${}^{150}$Nd $\to$ ${}^{150}$Sm(0${}_1^{+}$) is measured as $T_{1/2}=[4.7_{-1.9}^{+4.1}\text{(stat)}\pm 0.5\text{(syst)}]\times 10^{19}y$, in agreement with results of previous experiments.

   nucl-exNucl.Phys.Atom.Energy(2018)·10 citations
3. 03*

   Estimating initial state and quark-gluon plasma medium properties using a hybrid model with nucleon substructure calibrated to $p$-Pb and Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV

   J. Scott Moreland🇺🇸 · Jonah E. Bernhard🇺🇸 · Steffen A. Bass🇺🇸

   We posit a unified hydrodynamic and microscopic description of the quark-gluon plasma (QGP) produced in ultrarelativistic $p$-Pb and Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV and evaluate our assertion using Bayesian inference. Specifically, we model the dynamics of both collision systems using initial conditions with parametric nucleon substructure, a pre-equilibrium free-streaming stage, event-by-event viscous hydrodynamics, and a microscopic hadronic afterburner. Free parameters of the model which describe the initial state and QGP medium are then simultaneously calibrated to fit charged particle yields, mean $p_T$, and flow cumulants. We argue that the global agreement of the calibrated model with the experimental data strongly supports the existence of hydrodynamic flow in small collision systems at ultrarelativistic energies, and that the flow produced develops at length scales smaller than a single proton. Posterior estimates for the model's input parameters are obtained, and new insights into the temperature dependence of the QGP transport coefficients and event-by-event structure of the proton are discussed.

   ↳ nucl-thnucl-exPRC(2020)·168 citations
4. 04*

   Extraction of $\gamma n\to \pi N$ observables from deuteron-target data

   Satoshi X. Nakamura (Universidade Cruzeiro do Sul)🇧🇷

   An examination is conducted on a commonly used procedure for extracting (un)polarized $\gamma n\to {\pi }^{-}p$ and $\gamma n\to {\pi }^{0}n$ observables from $d(\gamma ,{\pi }^{-})pp$ and $d(\gamma ,{\pi }^0)pn$ data, using a model that consists of the impulse term and the final-state interaction (FSI) terms due to nucleon- and pion-exchange. Recent experimental and theoretical analyses used an extraction method that does not impose a cut on the final $\pi N$ invariant mass $W$. I demonstrate that the use of this method can result in the $\gamma n\to \pi N$ observables that are seriously distorted by the nucleon Fermi motion, and that one can efficiently avoid this problem by imposing a cut on $W$. It is also shown that the use of kinematical cuts of recent experimental analyses can still leave in the selected samples substantial FSI effects that must be corrected in extracting the $\gamma n\to \pi N$ cross sections. In terms of the nucleon- and pion-exchange mechanisms, I give the first qualitative explanation of the FSI corrections, obtained in a recent MAMI experiment, for extracting $\gamma n\to {\pi }^{0}n$ cross sections.

   ↳ nucl-thhep-phnucl-exPRC(2018)·14 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.