Wed·Dec 19, 2018Wednesday·December 19, 2018

1. 01*

   Sub-threshold production of K^{0}_{s} mesons and {\Lambda} hyperons in Au(1.23A GeV)+Au

   HADES collaboration: J. Adamczewski-Musch · O. Arnold · C. Behnke · A. Belounnas · A. Belyaev · J.C. Berger-Chen · J. Biernat · A. Blanco · C. Blume · M. Böhmer · P. Bordalo · S. Chernenko and 103 other authors

   We present first data on sub-threshold production of K0 s mesons and {\Lambda} hyperons in Au+Au collisions at $\sqrt{s_{NN}}$ = 2.4 GeV. We observe an universal <Apart> scaling of hadrons containing strangeness, independent of their corresponding production thresholds. Comparing the yields, their <Apart> scaling, and the shapes of the rapidity and the pt spectra to state-of-the-art transport model (UrQMD, HSD, IQMD) predictions, we find that none of the latter can simultaneously describe all observables with reasonable ḩi}2 values.

   nucl-exPLB(2019)·63 citations
2. 02*

   ${\beta }^{-}$ decay study of the ${}^{66}$Mn - ${}^{66}$Fe - ${}^{66}$Co - ${}^{66}$Ni chain

   M. Stryjczyk🇧🇪 · Y. Tsunoda🇯🇵 · I. G. Darby🇧🇪 · H. De Witte🇧🇪 · J. Diriken🇧🇪 · D. V. Fedorov🇷🇺 · V. N. Fedosseev🇨🇭 · L. M. Fraile🇪🇸 · M. Huyse🇧🇪 · U. Köster🇫🇷 · B. A. Marsh🇨🇭 · T. Otsuka🇯🇵 and 10 other authors

   Background: Shell evolution can impact the structure of the nuclei and lead to effects such as shape coexistence. The nuclei around ${}^{68}$Ni represent an excellent study case, however, spectroscopic information of the neutron-rich, $Z<28$ nuclei is limited. Purpose: The goal is to measure $\gamma$-ray transitions in ${}^{66}$Fe, ${}^{66}$Co and ${}^{66}$Ni populated in the ${\beta }^{-}$ decay of ${}^{66}$Mn, to determine absolute $\beta$-feedings and relative $\gamma$-decay probabilities and to compare the results with Monte Carlo Shell Model calculations in order to study the influence of the relevant single neutron and proton orbitals occupancies around $Z=28$ and $N=40$. Method: The low-energy structures of ${}^{65,66}$Fe, ${}^{66}$Co and ${}^{66}$Ni were studied in the ${\beta }^{-}$ decay of ${}^{66}$Mn produced at ISOLDE, CERN. The beam was purified by means of laser resonance ionization and mass separation. The $\beta$ and $\gamma$ events detected by three plastic scintillators and two MiniBall cluster germanium detectors, respectively, were correlated in time to build the low-energy excitation schemes and to determine the $\beta$-decay half-lives of the nuclei. Results: The relative small $\beta$-decay ground state feeding of ${}^{66}$Fe obtained in this work is at variant to the earlier studies. Spin and parity $1^{+}$ was assigned to the ${}^{66}$Co ground state based on the strong ground state feeding in the decay of ${}^{66}$Fe as well as in the decay of ${}^{66}$Co. Experimental log(ft) values, $\gamma$-ray deexcitation patterns and energies of excited states were compared to Monte Carlo Shell Model calculations. Based on this comparison, spin and parity assignments for the selected number of low-lying states in the ${}^{66}$Mn to ${}^{66}$Ni chain were proposed. Conclusions: The $\beta$-decay chain starting ${}^{66}$Mn towards ${}^{66}$Ni, crossing $N=40$, evolves from deformed nuclei to sphericity...

   nucl-exnucl-thPRC(2018)·19 citations
3. 03*

   Clusters in light stable and exotic nuclei

   C. Beck🇫🇷

   Since the discovery of molecular resonances in ${}^{12}$C+${}^{12}$C in the early sixties a great deal of research work has been undertaken to study alpha-clustering. Our knowledge on physics of nuclear molecules has increased considerably and nuclear clustering remains one of the most fruitful domains of nuclear physics, facing some of the greatest challenges and opportunities in the years ahead. Occurrence of "exotic" shapes and Bose-Einstein Condensates in light alpha-cluster nuclei are investigated. Various approaches of superdeformed/hyperdeformed shapes associated with quasimolecular resonant structures are discussed. The astrophysical reaction rate of 12C+12C is extracted from recent fusion measurements at deep subbarrier energies near the Gamov window. Evolution of clustering from stability to the drip-lines is examined.

   nucl-exnucl-th9 citations
4. 04*

   Forward photon measurements in ALICE as a probe for low-x gluons

   Thomas Peitzmann (for the ALICE Collaboration)🇳🇱

   The low-x gluon density in the proton and, in particular, in nuclei is only very poorly constrained, while a better understanding of the low-x structure is crucial for measurements at the LHC and also for the planning of experiments at future hadron colliders. In addition, deviations from linear QCD evolution are expected to appear at low x, potentially leading to gluon saturation and a universal state of hadronic matter, the color-glass condensate. However, these effects have not been unambiguously proven to date. Fortunately, data from the LHC can be used directly to provide better constraints of the parton distribution functions (PDFs). In this context, a Forward Calorimeter (FoCal) is proposed as an addition to the ALICE experiment, to be installed in the Long Shutdown 3. The main goal of the FoCal proposal is to measure forward direct photons in pp and p-Pb collisions to obtain experimental constraints on proton and nuclear PDFs in a new region of low x. Based on the current knowledge from DIS experiments and first results from LHC, we will discuss the physics case for this proposed detector. While open charm measurements do provide important constraints, a photon measurement would provide additional unique information. The direct photon measurement requires a new electromagnetic calorimeter with extremely high granularity. The corresponding innovative design principle of a high-resolution Si-W sandwich calorimeter is discussed.

   ↳ hep-exnucl-exPoS(2018)·4 citations
5. 05*

   Jet quenching parameter in an expanding QCD plasma

   Edmond Iancu🇫🇷 · Pieter Taels🇮🇹 · Bin Wu🇨🇭

   We present a new definition of the jet quenching parameter $\hat{q}$ in a weakly-coupled quark-gluon plasma undergoing boost-invariant longitudinal expansion. We propose a boost-invariant definition of $\hat{q}$, which is proportional to the broadening of the angular variables $\eta$ (the pseudo-rapidity) and $\varphi$ (the azimuthal angle). We furthermore consider radiative corrections to $\hat{q}$ and find potentially large corrections enhanced by a double logarithm like the case of a static medium. But unlike for the static medium, these corrections are now local in (proper) time.

   ↳ hep-phhep-exnucl-exnucl-thPoS(2018)·0 citations
6. 06*

   Jet structure in integrated EPOS3-HQ approach

   Iurii Karpenko🇫🇷 · Martin Rohrmoser🇵🇱 · Pol Gossiaux🇫🇷 · Joerg Aichelin🇫🇷 · Klaus Werner🇫🇷

   We report on the first results for jet observables from a time-like parton cascade integrated with hydrodynamic evolution within the EPOS3-HQ framework. The hard (jet) partons are produced along with soft partons in the initial state EPOS approach. The soft partons, represented by strings, melt into a thermalized medium which is described by a 3 dimensional event-by-event viscous hydrodynamic approach. The jet partons then propagate in the hydrodynamically expanding medium. The total jet energy gets progressively `degraded' when the partons reaching a thermal energy scale are melted into the hydrodynamic medium via the source terms. The full evolution proceeds in a parallel mode, without separating the thermalized and jet parts. We demonstrate how the transverse expansion of the medium affects the jet structure, and how the medium itself is affected by the jet recoil.

   ↳ nucl-thhep-phnucl-exPoS(2018)·1 citation
7. 07*

   Jet substructure in high-energy hadron collisions

   Felix Ringer🇺🇸

   In the past years significant progress has been made toward achieving a quantitative understanding of jets and their substructure in high-energy proton-proton collisions from first principles in QCD. Precise measurements have become available from the experimental collaborations at the LHC and RHIC allowing a direct comparison of theoretical calculations and data. These developments make it possible to use jet substructure observables as precision probes in heavy-ion collisions. The radiation pattern inside jets contains valuable information about the hot and dense QCD medium which can be investigated using jet substructure techniques. By studying the soft sensitivity of the different observables it is possible to obtain important insights into the interaction of hard probes with the quark gluon plasma.

   ↳ hep-phhep-exnucl-exnucl-thPoS(2018)·0 citations
8. 08*

   An application of extensions of the Ramo-Shockley theorem to signals in silicon sensors

   Werner Riegler🇨🇭

   We discuss an extension of the Ramo-Shockley theorem that allows the calculation of signals in detectors that contain non-linear materials of arbitrary permittivity and finite conductivity (volume resistivity) as well as a static space-charge. The readout-electrodes can be connected by an arbitrary impedance network. This formulation is useful for the treatment of semiconductor sensors where the finite volume resistivity in the sensitive detector volume cannot be neglected. The signals are calculated by means of time dependent weighting fields and weighting vectors. These are calculated by adding voltage or current signals to the electrodes in question, which has a very practical application when using semiconductor device simulation programs. An analytic example for an un-depleted silicon sensor is given.

   ↳ physics.ins-dethep-exnucl-exNucl.Instrum.Meth.A(2019)·28 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.