Thu·Jan 26, 2017Thursday·January 26, 2017

1. 01*

   Bulk Properties of the Medium Produced in Relativistic Heavy-Ion Collisions from the Beam Energy Scan Program

   STAR Collaboration: L. Adamczyk · J. K. Adkins · G. Agakishiev · M. M. Aggarwal · Z. Ahammed · N. N. Ajitanand · I. Alekseev · D. M. Anderson · R. Aoyama · A. Aparin · D. Arkhipkin · E. C. Aschenauer and 336 other authors

   We present measurements of bulk properties of the matter produced in Au+Au collisions at $\sqrt{s_{NN}}=$ 7.7, 11.5, 19.6, 27, and 39 GeV using identified hadrons (${\pi }^{\pm }$, $K^{\pm }$, $p$ and $\bar{p}$) from the STAR experiment in the Beam Energy Scan (BES) Program at the Relativistic Heavy Ion Collider (RHIC). Midrapidity ($|y|<$0.1) results for multiplicity densities $dN/dy$, average transverse momenta $⟨p_T⟩$ and particle ratios are presented. The chemical and kinetic freeze-out dynamics at these energies are discussed and presented as a function of collision centrality and energy. These results constitute the systematic measurements of bulk properties of matter formed in heavy-ion collisions over a broad range of energy (or baryon chemical potential) at RHIC.

   nucl-exPRC(2017)·879 citations
2. 02*

   Is the generalized Brink-Axel hypothesis valid?

   M. Guttormsen🇳🇴 · A. C. Larsen🇳🇴 · A. Görgen🇳🇴 · T. Renstrøm🇳🇴 · S. Siem🇳🇴 · T. G. Tornyi🇳🇴 · G. M. Tveten🇳🇴

   Experimental results of the ${}^{237}$Np($d,p\gamma {)}^{238}$Np reaction are presented, which verifies the generalized Brink-Axel (gBA) hypothesis for $\gamma$ transitions between states in the quasi-continuum. The gBA hypothesis holds not only for specific collective resonances, but for the full dipole strength below the neutron separation energy. We discuss the validity of the gBA hypothesis also for lighter systems like ${}^{92}$Zr where the concept of a unique $\gamma$-ray strength function ($\gamma$SF) is problematic due to large Porter-Thomas fluctuations. Methods for studying the $\gamma$SF and the fluctuations as function of excitation energy are presented.

   nucl-exPoS(2017)·2 citations
3. 03*

   One fluid to rule them all: viscous hydrodynamic description of event-by-event central p+p, p+Pb and Pb+Pb collisions at $\sqrt{s}=5.02$ TeV

   Ryan D. Weller🇺🇸 · Paul Romatschke🇺🇸

   The matter created in central p+p, p+Pb and Pb+Pb collisions at sqrt{s}=5.02 TeV is simulated event-by-event using the superSONIC model, which combines pre-equilibrium flow, viscous hydrodynamic evolution and late-stage hadronic rescatterings. Employing a generalization of the Monte Carlo Glauber model where each nucleon possesses three constituent quarks, superSONIC describes the experimentally measured elliptic and triangular flow at central rapidity in all systems using a single choice for the fluid parameters, such as shear and bulk viscosities. This suggests a common hydrodynamic origin of the experimentally observed flow patterns in all high energy nuclear collisions, including p+p.

   ↳ nucl-thhep-phnucl-exPLB(2017)·306 citations
4. 04*

   Spin polarization observables of the deuteron photodisintegration at low energies in pionless effective field theory

   Young-Ho Song🇰🇷 · Shung-Ichi Ando🇰🇷 · Chang Ho Hyun🇰🇷

   Spin polarization observables of the deuteron photodisintegration at low energies are studied in a pionless effective field theory up to next-to-next-to-leading order (NNLO). The total and differential cross sections, induced neutron polarization $P_{y^{\prime }}$, and tensor analyzing powers $T_{20}$ and $T_{22}$ of the process are calculated at photon energies from the breakup threshold to 20~MeV. We find that the NNLO corrections in the cross sections and $P_{y^{\prime }}$ converge well whereas they turn out to be important contributions in $T_{20}$ and $T_{22}$. We discuss the discrepancy between theory and experiment in $P_{y^{\prime }}$ still persisting as well as an implication of our result to the first measurement of $T_{20}$ at low energies in the HIGS facility.

   ↳ nucl-thnucl-exPRC(2017)·7 citations
5. 05*

   Consistent description of UCN transport properties

   S. Wlokka · P. Fierlinger🇩🇪 · A. Frei · P. Geltenbort🇫🇷 · S. Paul · T. Pöschl · F. Schmid · W. Schreyer🇨🇦 · D. Steffen🇨🇭

   We have investigated the diffuse reflection probabilities of Replica guides for ultra-cold neutrons (UCN) using the so-called helium method. For the first time we could establish a consistent description of the diffuse reflection mechanism for different lengths of the guide system. The transmission of the guides is measured depending on the helium pressure inside of the guides. A series of simulations was done to reproduce the experimental data. These simulations showed that a diffuse reflection probability of $d=(3.0\pm 0.5)\cdot 10^{-2}$ sufficiently describes the experimental data.

   ↳ physics.ins-detnucl-ex4 citations
6. 06*

   Suppression of alpha-induced lateral surface events in the COBRA experiment using CdZnTe detectors with an instrumented guard-ring electrode

   J.-H. Arling🇩🇪 · M. Gerhardt🇩🇪 · C. Gößling🇩🇪 · D. Gehre🇩🇪 · R. Klingenberg🇩🇪 · K. Kröninger🇩🇪 · C. Nitsch🇩🇪 · T. Quante🇩🇪 · K. Rohatsch🇩🇪 · J. Tebrügge🇩🇪 · R. Temminghoff🇩🇪 · R. Theinert🇩🇪 · S. Zatschler🇩🇪 · K. Zuber🇩🇪

   The COBRA collaboration searches for neutrinoless double beta-decay ($0\nu \beta \beta$-decay) using CdZnTe semiconductor detectors with a coplanar-grid readout and a surrounding guard-ring structure. The operation of the COBRA demonstrator at the Gran Sasso underground laboratory (LNGS) indicates that alpha-induced lateral surface events are the dominant source of background events. By instrumenting the guard-ring electrode it is possible to suppress this type of background. In laboratory measurements this method achieved a suppression factor of alpha-induced lateral surface events of $5300_{-1380}^{+2660}$, while retaining $85.3\pm 0.1\%$ of gamma events occurring in the entire detector volume. This suppression is superior to the pulse-shape analysis methods used so far in COBRA by three orders of magnitude.

   ↳ physics.ins-detnucl-exJINST(2017)·3 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.