Tue·Nov 8, 2016Tuesday·November 8, 2016

1. 01*

   Suppression of Upsilon(1S), Upsilon(2S), and Upsilon(3S) production in PbPb collisions at sqrt(s[NN]) = 2.76 TeV

   CMS Collaboration

   The production yields of Upsilon(1S), Upsilon(2S), and Upsilon(3S) quarkonium states are measured through their decays into muon pairs in the CMS detector, in PbPb and pp collisions at the centre-of-mass energy per nucleon pair of 2.76 TeV. The data correspond to integrated luminosities of 166 inverse microbarns and 5.4 inverse picobarns for PbPb and pp collisions, respectively. Differential production cross sections are reported as functions of Upsilon rapidity y up to 2.4, and transverse momentum pT up to 20 GeV/c. A strong centrality-dependent suppression is observed in PbPb relative to pp collisions, by factors of up to approximately 2 and 8, for the Upsilon(1S) and Upsilon(2S) states, respectively. No significant dependence of this suppression is observed as a function of y or pT. The Upsilon(3S) state is not observed in PbPb collisions, which corresponds to a suppression for the centrality-integrated data by at least a factor of approximately 7 at a 95% confidence level. The observed suppression is in agreement with theoretical scenarios modeling the sequential melting of quarkonium states in a quark gluon plasma.

   nucl-exPLB(2017)·167 citations
2. 02*

   Reactor Antineutrino Signals at Morton and Boulby

   Steve Dye🇺🇸

   Increasing the distance from which an antineutrino detector is capable of monitoring the operation of a registered reactor, or discovering a clandestine reactor, strengthens the Non-Proliferation of Nuclear Weapons Treaty. This report presents calculations of reactor antineutrino interactions, from quasi-elastic neutrino-proton scattering and elastic neutrino-electron scattering, in a water-based detector operated >10 km from a commercial power reactor. It separately calculates signal from the proximal reactor and background from all other registered reactors. The main results are interaction rates and kinetic energy distributions of charged leptons scattered from quasi-elastic and elastic processes. Comparing signal and background distributions evaluates reactor monitoring capability. Scaling the results to detectors of different sizes, target media, and standoff distances is straightforward. Calculations are for two examples of a commercial reactor (P_th~3 GW) operating nearby (L~20 km) an underground facility capable of hosting a detector (~1 kT H2O) project. These reactor-site combinations are Perry-Morton on the southern shore of Lake Erie in the U.S. and Hartlepool-Boulby on the western shore of the North Sea in U.K.. The signal from the proximal reactor is about five times greater at the Morton site than at the Boulby site due to shorter reactor-site separation distance, larger reactor thermal power, and greater neutrino oscillation survival probability. In terms of absolute interaction rate, background from all other reactors is larger at Morton than at Boulby. However, the fraction of the total rate is smaller at Morton than at Boulby. Moreover, the Hartlepool power plant has two cores whereas the Perry plant has a single core. The Boulby site, therefore, offers an opportunity for demonstrating remote reactor monitoring under more stringent conditions than does the Morton site.

   nucl-exphysics.ins-det0 citations
3. 03*

   Charged-particle nuclear modification factors in PbPb and pPb collisions at sqrt(s[NN]) = 5.02 TeV

   CMS Collaboration

   The spectra of charged particles produced within the pseudorapidity window abs(eta) < 1 at sqrt(s[NN]) = 5.02 TeV are measured using 404 inverse microbarns of PbPb and 27.4 inverse picobarns of pp data collected by the CMS detector at the LHC in 2015. The spectra are presented over the transverse momentum ranges spanning 0.5 < pt < 400 GeV in pp and 0.7 < pt < 400 GeV in PbPb collisions. The corresponding nuclear modification factor, R[AA], is measured in bins of collision centrality. The R[AA] in the 5% most central collisions shows a maximal suppression by a factor of 7-8 in the pt region of 6-9 GeV. This dip is followed by an increase, which continues up to the highest pt measured, and approaches unity in the vicinity of pt = 200 GeV. The R[AA] is compared to theoretical predictions and earlier experimental results at lower collision energies. The newly measured pp spectrum is combined with the pPb spectrum previously published by the CMS Collaboration to construct the pPb nuclear modification factor, R[pA], up to 120 GeV. For pt > 20 GeV, R[pA] exhibits weak momentum dependence and shows a moderate enhancement above unity.

   nucl-exJHEP(2017)·466 citations
4. 04*

   Jets and high-$p_T$ probes measured in the STAR experiment

   Nihar Ranjan Sahoo (for the STAR collaboration)🇺🇸

   Hard probes created through large momentum transfers are used to study the properties of QCD matter created in heavy-ion collisions, by comparing the measurements to those in p+p collisions. Jets, and the "quenching" or suppression of jets in the medium created in heavy-ion collisions, are studied through various different observables. We present the most recent measurements from $\sqrt{s_{NN}}$ = 200 GeV Au+Au collisions, with p+p collisions as the reference, by the STAR Collaboration. The observables are semi-inclusive charged jets and di-jet transverse momentum imbalance. Additionally, correlation measurements of direct photon-hadron and neutral pion-hadron are presented and discussed.

   nucl-exhep-exhep-phnucl-thPoS(2016)·0 citations
5. 05*

   Test of the Brink-Axel hypothesis for the pygmy dipole resonance

   D. Martin (1) · P. von Neumann-Cosel (1) · A. Tamii (2) · N. Aoi (2) · S. Bassauer (1) · C. A. Bertulani (3) · J. Carter (4) · L. Donaldson (4) · H. Fujita (2) · Y. Fujita (2) · T. Hashimoto (2) · K. Hatanaka (2) and 12 other authors

   The gamma strength function and level density of 1- states in 96Mo have been extracted from a high-resolution study of the (p,p') reaction at 295 MeV and extreme forward angles. By comparison with compound nucleus $\gamma$ decay experiments, this allows a test of the generalized Brink-Axel hypothesis in the energy region of the Pygmy Dipole Resonance. The Brink-Axel hypothesis is commonly assumed in astrophysical reaction network calculations and states that the gamma strength function in nuclei is independent of the structure of initial and final state. The present results validiate the Brink-Axel hypothesis for 96Mo and provide independent confirmation of the methods used to separate gamma strength function and level density in $\gamma$ decay experiments.

   nucl-exPRL(2017)·52 citations
6. 06*

   Production and interaction of the eta meson with nucleons and nuclei

   Wojciech Krzemien🇵🇱 · Oleksandr Khreptak🇵🇱 · Paweł Moskal🇵🇱 · Iryna Ozyrianska-Schätti🇵🇱 · Oleksandr Rundel🇵🇱 · Magdalena Skurzok🇵🇱 · Marcin Zieliński (for the WASA-at-COSY collaboration)🇵🇱

   We report on the status of the search for eta-mesic nuclei and the studies of the interaction of the eta meson with nucleons. Recently we have completed the analysis of the new WASA-at-COSY data on the production of the eta meson with polarized proton beam. New results on the analyzing power for the pp->ppeta reaction with more than an order of magnitude improved precision shed a new light on the production mechanism of the eta meson in nucleon-nucleon collisions. Also, the latest results of the search for eta-mesic nuclei are discussed.

   nucl-exEPJ Web Conf.(2016)·0 citations
7. 07*

   A New Track Reconstruction Algorithm suitable for Parallel Processing based on Hit Triplets and Broken Lines

   Andre Schöning🇩🇪

   Track reconstruction in high track multiplicity environments at current and future high rate particle physics experiments is a big challenge and very time consuming. The search for track seeds and the fitting of track candidates are usually the most time consuming steps in the track reconstruction. Here, a new and fast track reconstruction method based on hit triplets is proposed which exploits a three-dimensional fit model including multiple scattering and hit uncertainties from the very start, including the search for track seeds. The hit triplet based reconstruction method assumes a homogeneous magnetic field which allows to give an analytical solutions for the triplet fit result. This method is highly parallelizable, needs fewer operations than other standard track reconstruction methods and is therefore ideal for the implementation on parallel computing architectures. The proposed track reconstruction algorithm has been studied in the context of the Mu3e-experiment and a typical LHC experiment.

   ↳ physics.ins-dethep-exnucl-exEPJ Web Conf.(2016)·5 citations
8. 08*

   Symmetry Energy III: Isovector Skins

   Pawel Danielewicz (NSCL MSU)🇺🇸 · Pardeep Singh (DCRUST)🇫🇷 · Jenny Lee (U Hong Kong)🇨🇳

   Isoscalar density is a sum of neutron and proton densities and isovector is a normalized difference. Here, we report on the experimental evidence for the displacement of the isovector and isoscalar surfaces in nuclei, by $\sim$$0.9\text{fm}$ from each other. We analyze data on quasielastic (QE) charge exchange (p,n) reactions, concurrently with proton and neutron elastic scattering data for the same target nuclei, following the concepts of the isoscalar and isovector potentials combined into Lane optical potential. The elastic data largely probe the geometry of the isoscalar potential and the (p,n) data largely probe a relation between the geometries of the isovector and isoscalar potentials. The targets include ${}^{48}$Ca, ${}^{90}$Zr, ${}^{120}$Sn and ${}^{208}$Pb and projectile incident energy values span the range of (10-50)$\text{MeV}$. In our fit to elastic and QE charge-exchange data, we allow the values of isoscalar and isovector radii, diffusivities and overall potential normalizations to float away from those in the popular Koning and Delaroche parametrization. We find that the best-fit isovector radii are consistently larger than isoscalar and the best-fit isovector surfaces are steeper. Upon identifying the displacement of the potential surfaces with the displacement of the surfaces for the densities in the Skyrme-Hartree-Fock calculations, and by supplementing the results with those from analysing excitation energies to isobaric analog states in the past, we arrive at the slope and value of the symmetry energy at normal density of $70<L<101\text{MeV}$ and $33.5<a_a^V<36.4\text{MeV}$, respectively.

   ↳ nucl-thnucl-exNPA(2017)·90 citations
9. 09*

   Data Unfolding Methods in High Energy Physics

   Stefan Schmitt🇩🇪

   A selection of unfolding methods commonly used in High Energy Physics is compared. The methods discussed here are: bin-by-bin correction factors, matrix inversion, template fit, Tikhonov regularisation and two examples of iterative methods. Two procedures to choose the strength of the regularisation are tested, namely the L-curve scan and a scan of global correlation coefficients. The advantages and disadvantages of the unfolding methods and choices of the regularisation strength are discussed using a toy example.

   ↳ physics.data-anhep-exnucl-exEPJ Web Conf.(2017)·109 citations
10. 10*

    Theoretical photo-disintegration of ${}^{16}$O

    M. Katsuma

    The photodisintegration of ${}^{16}$O is predicted to be dominated by $E$2 excitation in the vicinity of the $\alpha$-particle threshold. The reaction rates of ${}^{12}$C($\alpha$,$\gamma$)${}^{16}$O are expected to be determined from this reaction.

    ↳ nucl-thastro-ph.SRnucl-exJPS Conf.Proc.(2017)·2 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.