Fri·May 12, 2017Friday·May 12, 2017

1. 01*

   Future prospects for neutrinoless double-beta decay

   Sergio Di Domizio🇮🇹

   The study of neutrinoless double-beta decay plays a fundamental role in the understanding of neutrino physics. Its observation would prove that neutrinos are Majorana particles and that lepton number is not conserved. Experimental searches demand detectors with a very large source mass and extremely low background. We report on planned future experimental searches and discuss their expected sensitivities.

   nucl-exphysics.ins-det2 citations
2. 02*

   A short-orbit spectrometer for low-energy pion detection in electroproduction experiments at MAMI

   D. Baumann🇩🇪 · M. Ding🇩🇪 · I. Friščić🇭🇷 · R. Böhm🇩🇪 · D. Bosnar🇭🇷 · M. O. Distler🇩🇪 · H. Merkel🇩🇪 · U. Müller🇩🇪 · Th. Walcher🇩🇪 · M. Wendel

   A new Short-Orbit Spectrometer (SOS) has been constructed and installed within the experimental facility of the A1 collaboration at Mainz Microtron (MAMI), with the goal to detect low-energy pions. It is equipped with a Browne-Buechner magnet and a detector system consisting of two helium-ethane based drift chambers and a scintillator telescope made of five layers. The detector system allows detection of pions in the momentum range of 50 - 147 MeV/c, which corresponds to 8.7 - 63 MeV kinetic energy. The spectrometer can be placed at a distance range of 54 - 66 cm from the target center. Two collimators are available for the measurements, one having 1.8 msr aperture and the other having 7 msr aperture. The Short-Orbit Spectrometer has been successfully calibrated and used in coincidence measurements together with the standard magnetic spectrometers of the A1 collaboration.

   ↳ physics.ins-detnucl-exNucl.Instrum.Meth.A(2017)·0 citations
3. 03*

   Parity partners in the baryon resonance spectrum

   Ya Lu🇨🇳 · Chen Chen🇧🇷 · Craig D. Roberts🇺🇸 · Jorge Segovia🇩🇪 · Shu-Sheng Xu🇨🇳 · Hong-Shi Zong🇨🇳

   We describe a calculation of the spectrum of flavour-SU(3) octet and decuplet baryons, their parity partners, and the radial excitations of these systems, made using a symmetry-preserving treatment of a vector-vector contact interaction as the foundation for the relevant few-body equations. Dynamical chiral symmetry breaking generates nonpointlike diquarks within these baryons and hence, using the contact interaction, flavour-antitriplet scalar, pseudoscalar and vector, and flavour-sextet axial-vector quark-quark correlations can all play an active role. The model yields reasonable masses for all systems studied, and Faddeev amplitudes for ground states and associated parity partners that sketch a realistic picture of their internal structure: ground-state, even parity baryons are constituted, almost exclusively, from like-parity diquark correlations; but orbital angular momentum plays an important role in the rest-frame wave functions of odd-parity baryons, whose Faddeev amplitudes are dominated by odd-parity diquarks.

   ↳ nucl-thhep-lathep-phnucl-exPRC(2017)·53 citations
4. 04*

   Measurement of multi-particle azimuthal correlations in $pp$, $p$+Pb and low-multiplicity Pb+Pb collisions with the ATLAS detector

   ATLAS Collaboration

   Multi-particle cumulants and corresponding Fourier harmonics are measured for azimuthal angle distributions of charged particles in $pp$ collisions at $\sqrt{s}$ = 5.02 and 13 TeV and in $p$+Pb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV, and compared to the results obtained for low-multiplicity Pb+Pb collisions at $\sqrt{s_{NN}}$ = 2.76 TeV. These measurements aim to assess the collective nature of particle production. The measurements of multi-particle cumulants confirm the evidence for collective phenomena in $p$+Pb and low-multiplicity Pb+Pb collisions. On the other hand, the $pp$ results for four-particle cumulants do not demonstrate collective behaviour, indicating that they may be biased by contributions from non-flow correlations. A comparison of multi-particle cumulants and derived Fourier harmonics across different collision systems is presented as a function of the charged-particle multiplicity. For a given multiplicity, the measured Fourier harmonics are largest in Pb+Pb, smaller in $p$+Pb and smallest in $pp$ collisions. The $pp$ results show no dependence on the collision energy, nor on the multiplicity.

   ↳ hep-exnucl-exEPJC(2017)·179 citations
5. 05*

   Iso-vector dipole resonance and shear viscosity in low energy heavy-ion collision

   C. Q. Guo🇨🇳 · Y. G. Ma🇨🇳 · W. B. He · X. G. Cao🇨🇳 · D. Q. Fang🇨🇳 · X. G. Deng🇨🇳 · C. L. Zhou🇨🇳

   The ratio of shear viscosity over entropy density in low energy heavy-ion collision has been calculated by using the Green-Kubo method in the framework of an extended quantum molecular dynamics model. After the system almost reaching a local equilibration for a head-on ${}^{40}$Ca+${}^{100}$Mo collision, thermodynamic and transport properties are extracted. Meanwhile, iso-vector giant dipole resonance (IVGDR) of the collision system is also studied. By the Gaussian fits to the IVGDR photon spectra, the peak energies of IVGDR are extracted at different incident energies. The result shows that the IVGDR peak energy has a positive correlation with the ratio of shear viscosity over entropy density. This is a quantum effect and indicates a difference between nuclear matter and classical fluid.

   ↳ nucl-thnucl-exPRC(2017)·17 citations
6. 06*

   Investigation of giant dipole resonance in heavy deformed nuclei with the EQMD model

   S. S. Wang🇨🇳 · Y. G. Ma🇨🇳 · X. G. Cao🇨🇳 · W. B. He🇨🇳 · H. Y. Kong · C. W. Ma🇨🇳

   The deformation evolution of giant dipole resonance (GDR), in the chains of Sm and Nd isotopes, are investigated in the framework of an extended quantum molecular dynamics (EQMD) model. The mass number dependence of resonance peak position $(E_m)$ in the major and minor axis directions of deformed nuclei as well as the difference $\Delta E_m$ between them are described in detail. The correlation between the splitting ($\Delta E_m/{\bar{E}}_m$) of the GDR spectra and the deformation(${\beta }_2$) is further studied. The results confirm that $\Delta E_m/{\bar{E}}_m$ is proportional to ${\beta }_2$. By comparing the calculation with the experimental data on photon absorption cross section ${\sigma }_{\gamma }$, it shows that the EQMD model can quite well reproduce the shape of GDR spectra from spherical to prolate shape. The GDR shapes in ${}^{134}$Sm, ${}^{136}$Sm, ${}^{138}$Sm, ${}^{130}$Nd, ${}^{132}$Nd and ${}^{134}$Nd are also predicted. In addition, the symmetry energy coefficient $(E_{sym})$ dependence of GDR spectra of ${}^{150}$Nd is also discussed. It is found that the calculated GDR spectrum in the EQMD model is perfectly consistent with the experimental results when $E_{sym}$ equals to 32 MeV.

   ↳ nucl-thnucl-exPRC(2017)·19 citations
7. 07*

   Summing coincidence in rare event gamma-ray measurements under an ultra-low background environment

   Liu-Chun He🇨🇳 · Li-Jun Diao · Bao-Hua Sun🇨🇳 · Li-Hua Zhu🇨🇳 · Jian-Wei Zhao🇨🇳 · Meng Wang · Kang Wang🇨🇳

   A Monte Carlo method based on the GEANT4 toolkit has been developed to correct the full-energy peak (FEP) efficiencies of a high purity germanium (HPGe) detector equipped with a low background shielding system, and moreover evaluated using summing peaks in a numerical way. It is found that the FEP efficiencies of ${}^{60}$Co, ${}^{133}$Ba and ${}^{152}$Eu can be improved up to 18\% by taking the calculated true summing \mbox{coincidence} factors (TSCFs) correction into account. Counts of summing coincidence $\gamma$ peaks in the spectrum of ${}^{152}$Eu can be well reproduced using the corrected efficiency curve within an accuracy of 3\%.

   ↳ physics.ins-detnucl-exNucl.Instrum.Meth.A(2018)·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.