Mon·Feb 9, 2015Monday·February 9, 2015

1. 01*

   Measurement of jet suppression in central Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV

   ALICE Collaboration

   The transverse momentum ($p_{\mathrm{T}}$) spectrum and nuclear modification factor ($R_{\mathrm{AA}}$) of reconstructed jets in 0-10% and 10-30% central Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV were measured. Jets were reconstructed from charged and neutral particles, utilizing the ALICE tracking detectors and Electromagnetic Calorimeter (EMCal), with the anti-$k_{\mathrm{T}}$ jet algorithm with a resolution parameter of R=0.2. The jet $p_{\mathrm{T}}$ spectra are reported in the pseudorapidity interval of $|{\eta }_{\mathrm{jet}}|<0.5$ for $40<p_{\mathrm{T},\mathrm{jet}}<120$ GeV/$c$ in 0-10% and for $30<p_{\mathrm{T},\mathrm{jet}}<100$ GeV/$c$ in 10-30% collisions. Reconstructed jets were required to contain a leading charged particle with $p_{\mathrm{T}}>5$ GeV/$c$ to suppress jets constructed from the combinatorial background in Pb-Pb collisions. The effect of the leading charged particle requirement has been studied in both pp and Pb-Pb collisions and has been shown to have negligible effects on the $R_{\mathrm{AA}}$ within the uncertainties of the measurement. The nuclear modification factor is obtained by dividing the jet spectrum measured in Pb-Pb by that in pp collisions scaled by the number of independent nucleon-nucleon collisions estimated using a Glauber model. $R_{\mathrm{AA}}$ is found to be $0.28\pm 0.04$ in 0-10% and $0.35\pm 0.04$ in 10-30% collisions, independent of $p_{\mathrm{T},\mathrm{jet}}$ within the uncertainties of the measurement. The observed suppression is in fair agreement with expectations from two model calculations with different approaches to jet quenching.

   nucl-exhep-exPLB(2015)·255 citations
2. 02*

   Direct photon production at RHIC and LHC energies

   O. Linnyk🇩🇪 · E. L. Bratkovskaya🇩🇪 · W. Cassing🇩🇪

   Direct photon spectra and elliptic flow v2 in heavy-ion collisions at RHIC and LHC energies are investigated within a relativistic transport approach incorporating both hadronic and partonic phases - the Parton-Hadron-String Dynamics (PHSD). The results suggest that a large v2 of the direct photons - as observed by the PHENIX Collaboration - signals a significant contribution of photons produced in interactions of secondary mesons and baryons in the late stages of the collision. In order to further differentiate the origin of the direct photon azimuthal asymmetry, we compare our predictions for the centrality dependence of the direct photon yield to the recent measurements by the PHENIX Collaboration and provide predictions for Pb+Pb collisions at LHC energies with respect to the direct photon spectra and v2(pT) for 0-40% centrality.

   ↳ nucl-thhep-phnucl-exPoS(2015)·1 citation
3. 03*

   MAJORANA Collaboration's Experience with Germanium Detectors

   S. Mertens🇺🇸 · N. Abgrall🇺🇸 · F. T. Avignone III🇺🇸 · A. S. Barabash🇷🇺 · F. E. Bertrand🇺🇸 · V. Brudanin🇷🇺 · M. Busch🇺🇸 · M. Buuck🇺🇸 · D. Byram🇺🇸 · A.S. Caldwell🇺🇸 · Y-D. Chan🇺🇸 · C. D. Christofferson🇺🇸 and 53 other authors

   The goal of the \textsc{Majorana} \textsc{Demonstrator} project is to search for 0$\nu \beta \beta$ decay in ${}^{76}\mathrm{Ge}$. Of all candidate isotopes for 0$\nu \beta \beta$, ${}^{76}\mathrm{Ge}$ has some of the most favorable characteristics. Germanium detectors are a well established technology, and in searches for 0$\nu \beta \beta$, the high purity germanium crystal acts simultaneously as source and detector. Furthermore, p-type germanium detectors provide excellent energy resolution and a specially designed point contact geometry allows for sensitive pulse shape discrimination. This paper will summarize the experiences the \textsc{Majorana} collaboration made with enriched germanium detectors manufactured by ORTEC${}^{\circledR }$. The process from production, to characterization and integration in \textsc{Majorana} mounting structure will be described. A summary of the performance of all enriched germanium detectors will be given.

   ↳ physics.ins-detnucl-exJ.Phys.Conf.Ser.(2015)·12 citations
4. 04*

   The Majorana Parts Tracking Database

   The Majorana Collaboration: N. Abgrall (5)🇺🇸 · E. Aguayo (13)🇺🇸 · F. T. Avignone III (17 and 11)🇺🇸 · A. S. Barabash (3)🇷🇺 · F. E. Bertrand (11)🇺🇸 · V. Brudanin (4)🇷🇺 · M. Busch (9 and 20)🇺🇸 · D. Byram (18)🇺🇸 · A. S. Caldwell (15)🇺🇸 · Y-D. Chan (5)🇺🇸 · C. D. Christofferson (15)🇺🇸 · D. C. Combs (10 and 20)🇺🇸 and 79 other authors

   The Majorana Demonstrator is an ultra-low background physics experiment searching for the neutrinoless double beta decay of ${}^{76}$Ge. The Majorana Parts Tracking Database is used to record the history of components used in the construction of the Demonstrator. The tracking implementation takes a novel approach based on the schema-free database technology CouchDB. Transportation, storage, and processes undergone by parts such as machining or cleaning are linked to part records. Tracking parts provides a great logistics benefit and an important quality assurance reference during construction. In addition, the location history of parts provides an estimate of their exposure to cosmic radiation. A web application for data entry and a radiation exposure calculator have been developed as tools for achieving the extreme radio-purity required for this rare decay search.

   ↳ physics.ins-detnucl-exNucl.Instrum.Meth.A(2015)·21 citations
5. 05*

   PMT signal increase using a wavelength shifting paint

   K. Allada🇺🇸 · Ch. Hurlbut🇺🇸 · L. Ou🇺🇸 · B. Schmookler🇺🇸 · A. Shahinyan🇦🇲 · B. Wojtsekhowski🇺🇸

   We report a 1.65 times increase of the PMT signal and a simple procedure of application of a new wavelength shifting (WLS) paint for PMTs with non-UV-transparent windows. Samples of four different WLS paints, made from hydrocarbon polymers and organic fluors, were tested on a 5-inch PMT (ET 9390KB) using Cherenkov radiation produced in fused silica disks by ${}^{106}$Ru electrons on a `table-top' setup. The best performing paint was employed on two different types of 5-inch PMTs (ET 9390KB and XP4572B), installed in atmospheric pressure CO${}_2$ gas Cherenkov detectors, and tested using GeV electrons.

   ↳ physics.ins-detnucl-exNucl.Instrum.Meth.A(2015)·4 citations
6. 06*

   Study of digital pulse shape discrimination method for n-{\gamma} separation of EJ-301 liquid scintillation detector

   Bo Wan · Xueying Zhang · Liang Chen🇺🇸 · Honglin Ge🇺🇸 · Fei Ma🇨🇳 · Hongbin Zhang🇨🇳 · Yongqin Ju · Yanbin Zhang · Yanyan Li · Xiaowei Xu🇩🇪

   A digital pulse shape discrimination system based on a programmable module NI-5772 has been established and tested with EJ-301 liquid scintillation detector. The module was operated by means of running programs developed in LabVIEW with the sampling frequency up to 1.6GS/s. Standard gamma sources 22Na, 137Cs and 60Co were used to calibrate the EJ-301 liquid scintillation detector, and the gamma response function has been obtained. Digital algorithms for charge comparison method and zero-crossing method have been developed. The experimental results showed that both digital signal processing (DSP) algorithms could discriminate neutrons from gamma-rays. Moreover, the zero-crossing method shows better n-{\gamma} discrimination at 80 keVee and lower, whereas the charge comparison method gives better results at higher thresholds. In addition, the figure-of-merit (FOM) of two different dimension detectors were extracted at 9 energy thresholds, and it was found that the smaller one presented a better n-{\gamma} separation property for fission neutrons.

   ↳ physics.ins-detnucl-exCPC(2015)·2 citations
7. 07*

   Deuteron-deuteron scattering above four-nucleon breakup threshold

   A. Deltuva🇱🇹 · A. C. Fonseca🇵🇹

   Deuteron-deuteron elastic scattering and transfer reactions in the energy regime above four-nucleon breakup threshold are described by solving exact four-particle equations for transition operators. Several realistic nuclear interaction models are used, including the one with effective many-nucleon forces generated by the explicit $\Delta$-isobar excitation; the Coulomb force between protons is taken into account as well. Differential cross sections, deuteron analyzing powers, outgoing nucleon polarization, and deuteron-to-neutron polarization transfer coefficients are calculated at 10 MeV deuteron energy. Overall good agreement with the experimental data is found. The importance of breakup channels is demonstrated.

   ↳ nucl-thnucl-exPLB(2015)·23 citations
8. 08*

   International Spin Physics 2014 Summary

   Richard G. Milner🇺🇸

   The Stern-Gerlach experiment and the origin of electron spin are described in historical context. SPIN 2014 occurs on the fortieth anniversary of the first International High Energy Spin Physics Symposium at Argonne in 1974. A brief history of the international spin conference series is presented.

   ↳ physics.hist-phnucl-ex0 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.