Wed·Aug 2, 2017Wednesday·August 2, 2017

1. 01*

   Relating centrality to impact parameter in nucleus-nucleus collisions

   Sruthy Jyothi Das🇫🇷 · Giuliano Giacalone🇫🇷 · Pierre-Amaury Monard🇫🇷 · Jean-Yves Ollitrault🇫🇷

   In ultrarelativistic heavy-ion experiments, one estimates the centrality of a collision by using a single observable, say $n$, typically given by the transverse energy or the number of tracks observed in a dedicated detector. The correlation between $n$ and the impact parameter, $b$, of the collision is then inferred by fitting a specific model of the collision dynamics, such as the Glauber model, to experimental data. The goal of this paper is to assess precisely which information about $b$ can be extracted from data without any specific model of the collision. Under the sole assumption that the probability distribution of $n$ for a fixed $b$ is Gaussian, we show that the probability distribution of the impact parameter in a narrow centrality bin can be accurately reconstructed up to $5\%$ centrality. We apply our methodology to data from the Relativistic Heavy Ion Collider and the Large Hadron Collider. We propose a simple measure of the precision of the centrality determination, which can be used to compare different experiments.

   ↳ nucl-thhep-phnucl-exPRC(2018)·72 citations
2. 02*

   Mitigation of ${}^{42}$Ar/${}^{42}$K background for the GERDA Phase II experiment

   A. Lubashevskiy🇷🇺 · M. Agostini🇮🇹 · D. Budjáš🇩🇪 · A. Gangapshev🇷🇺 · K. Gusev🇷🇺 · M. Heisel🇩🇪 · A. Klimenko🇩🇪 · A. Lazzaro🇩🇪 · B. Lehnert🇩🇪 · K. Pelczar🇵🇱 · S. Schönert🇩🇪 · A. Smolnikov🇩🇪 · M. Walter🇨🇭 · G. Zuzel🇵🇱

   Background coming from the ${}^{42}$Ar decay chain is considered to be one of the most relevant for the GERDA experiment, which aims to search of the neutrinoless double beta decay of ${}^{76}$Ge. The sensitivity strongly relies on the absence of background around the Q-value of the decay. Background coming from ${}^{42}$K, a progeny of ${}^{42}$Ar, can contribute to that background via electrons from the continuous spectrum with an endpoint of 3.5 MeV. Research and development on the suppression methods targeting this source of background were performed at the low-background test facility LArGe. It was demonstrated that by reducing ${}^{42}$K ion collection on the surfaces of the broad energy germanium detectors in combination with pulse shape discrimination techniques and an argon scintillation veto, it is possible to suppress the ${}^{42}$K background by three orders of magnitude. This is sufficient for Phase II of the GERDA experiment.

   ↳ physics.ins-dethep-exnucl-exEPJC(2018)·39 citations
3. 03*

   Energy-resolved fast neutron resonance radiography at CSNS

   Zhixin Tan🇨🇳 · Jingyu Tang🇨🇳 · Hantao Jing🇨🇳 · Ruirui Fan🇨🇳 · Qiang Li🇨🇳 · Changjun Ning🇨🇳 · Jie Bao🇨🇳 · Xichao Ruan🇨🇳 · Guangyuan Luan🇨🇳 · Changqin Feng🇨🇳 · Xianpeng Zhang🇨🇳

   The white neutron beamline at the China Spallation Neutron Source will be used mainly for nuclear data measurements. It will be characterized by high flux and broad energy spectra. To exploit the beamline as a neutron imaging source, we propose a liquid scintillator fiber array for fast neutron resonance radiography. The fiber detector unit has a small exposed area, which will limit the event counts and separate the events in time, thus satisfying the requirements for single-event time-of-flight (SEToF) measurement. The current study addresses the physical design criteria for ToF measurement, including flux estimation and detector response. Future development and potential application of the technology are also discussed.

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