Wed·Apr 1, 2020Wednesday·April 1, 2020

1. 01*

   Neutron-neutron quasifree scattering in neutron-deuteron breakup at 10 MeV

   R. C. Malone (1 and 2)🇺🇸 · A. S. Crowell (1 and 2) · L. C. Cumberbatch (1 and 2) · B. A. Fallin (1 and 2) · F. Q. L. Friesen (1 and 2)🇺🇸 · C. R. Howell (1 and 2)🇺🇸 · C. R. Malone (1 and 2) · D. R. Ticehurst (1 and 2) · W. Tornow (1 and 2)🇺🇸 · D. M. Markoff (2 and 3)🇺🇸 · B. J. Crowe (2 and 3) · H. Witała (4) ((1) Department of Physics, Duke University, Durham, NC, (2) Triangle Universities Nuclear Laboratory, Durham, NC, (3) Department of Mathematics and Physics, North Carolina Central University, Durham, NC, (4) M. Smoluchowski Institute of Physics, Jagiellonian University, Krakòw, Poland)🇵🇱

   New measurements of the neutron-neutron quasifree scattering cross section in neutron-deuteron breakup at an incident neutron energy of 10.0 MeV are reported. The experiment setup was optimized to evaluate the technique for determining the integrated beam-target luminosity in neutron-neutron coincidence cross-section measurements in neutron-deuteron breakup. The measurements were carried out with a systematic uncertainty of $\pm 5.6\%$. Our data are in agreement with theoretical calculations performed using the CD-Bonn nucleon-nucleon potential in the Faddeev formalism. The measured integrated cross section over the quasifree peak is $20.5\pm 0.5\text{(stat)}\pm 1.1\text{(sys)}$ mb/sr${}^2$ in comparison with the theory prediction of 20.1 mb/sr${}^2$. These results validate our technique for determining the beam-target luminosity in neutron-deuteron breakup measurements.

   nucl-exPRC(2020)·2 citations
2. 02*

   Core meets corona: a two-component source to explain Lambda and anti-Lambda global polarization in semi-central heavy-ion collisions

   Alejandro Ayala🇲🇽 · Marco Alberto Ayala Torres🇲🇽 · Eleazar Cuautle🇲🇽 · Isabel Dominguez🇲🇽 · Marcos Aurelio Fontaine Sanchez🇲🇽 · Ivonne Maldonado🇲🇽 · E. Moreno-Barbosa🇲🇽 · P. A. Nieto-Marin🇲🇽 · M. Rodriguez-Cahuantzi🇲🇽 · Jordi Salinas🇲🇽 · Maria Elena Tejeda-Yeomans🇲🇽 · L. Valenzuela-Cazares🇲🇽

   We compute the Lambda and anti-Lambda global polarization in semi-central heavy-ion collisions modeling the source as consisting of a high-density core and a less dense corona. We show that when more Lambdas than anti-Lambdas are produced in the corona, and this is combined with a smaller number of Lambdas coming from the core, as compared to those coming from the corona, an amplification effect for the anti-Lambda with respect to that of Lambda polarization can occur. This amplification becomes more important for lower collision energies and quantitatively accounts for the Lambda and anti-Lambda polarizations measured by the STAR beam energy scan.

   ↳ hep-phnucl-exnucl-thPLB(2020)·35 citations
3. 03*

   Characterization of High-Purity Germanium Detectors with Amorphous Germanium Contacts in Cryogenic Liquids

   R. Panth🇺🇸 · J. Liu🇺🇸 · I. Abt🇩🇪 · X. Liu🇨🇳 · O. Schulz🇩🇪 · W.-Z. Wei🇺🇸 · H. Mei🇺🇸 · D.-M. Mei🇺🇸 · G.-J. Wang🇺🇸

   For the first time, planar high-purity germanium detectors with thin amorphous germanium contacts were successfully operated directly in liquid nitrogen and liquid argon in a cryostat at the Max-Planck-Institut fuer Physics in Munich. The detectors were fabricated at the Lawrence Berkeley National Laboratory and the University of South Dakota, using crystals grown at the University of South Dakota. They survived long-distance transportation and multiple thermal cycles in both cryogenic liquids and showed reasonable leakage currents and spectroscopic performance. Also discussed are the pros and cons of using thin amorphous semiconductor materials as an alternative contact technology in large-scale germanium experiments searching for physics beyond the Standard Model.

   ↳ physics.ins-detnucl-exEPJC(2020)·7 citations
4. 04*

   Investigating the diffractive gluon jet production in lepton-ion collisions

   G. M. Peccini🇧🇷 · L. S. Moriggi🇧🇷 · M.V.T. Machado🇧🇷

   We study the diffractive jet production in electron-ion collisions in the kinematical region where the mass $M_X$ of the diffractive final state is larger than $Q^2$. Based on parton saturation framework predictions are done for the kinematics of future or possible $eA$ machines as the EIC, LHeC, HE-LHeC and FCC-eA. We analyze the differential cross section as a function of jet (gluon) transverse momentum and from the experimental point of view this observable could be used to extract the saturation scale as a function of $x_{IP}$.

   ↳ hep-phhep-exnucl-exPRC(2020)·11 citations
5. 05*

   Connecting fluctuation measurements in heavy-ion collisions with the grand-canonical susceptibilities

   Volodymyr Vovchenko🇩🇪 · Oleh Savchuk🇺🇦 · Roman V. Poberezhnyuk🇺🇦 · Mark I. Gorenstein🇺🇦 · Volker Koch🇺🇸

   We derive the relation between cumulants of a conserved charge measured in a subvolume of a thermal system and the corresponding grand-canonical susceptibilities, taking into account exact global conservation of that charge. The derivation is presented for an arbitrary equation of state, with the assumption that the subvolume is sufficiently large to be close to the thermodynamic limit. Our framework -- the subensemble acceptance method (SAM) -- quantifies the effect of global conservation laws and is an important step toward a direct comparison between cumulants of conserved charges measured in central heavy ion collisions and theoretical calculations of grand-canonical susceptibilities, such as lattice QCD. As an example, we apply our formalism to net-baryon fluctuations at vanishing baryon chemical potentials as encountered in collisions at the LHC and RHIC.

   ↳ hep-phnucl-exnucl-thPLB(2020)·87 citations
6. 06*

   Efficient Machine Learning Approach for Optimizing the Timing Resolution of a High Purity Germanium Detector

   R. W. Gladen🇺🇸 · V. A. Chirayath🇺🇸 · A. J. Fairchild🇺🇸 · M. T. Manry🇺🇸 · A. R. Koymen🇺🇸 · A. H. Weiss🇺🇸

   We describe here an efficient machine-learning based approach for the optimization of parameters used for extracting the arrival time of waveforms, in particular those generated by the detection of 511 keV annihilation gamma-rays by a 60 cm3 coaxial high purity germanium detector (HPGe). The method utilizes a type of artificial neural network (ANN) called a self-organizing map (SOM) to cluster the HPGe waveforms based on the shape of their rising edges. The optimal timing parameters for HPGe waveforms belonging to a particular cluster are found by minimizing the time difference between the HPGe signal and a signal produced by a BaF2 scintillation detector. Applying these variable timing parameters to the HPGe signals achieved a gamma-coincidence timing resolution of ~ 4.3 ns at the 511 keV photo peak (defined as 511 +- 50 keV) and a timing resolution of ~ 6.5 ns for the entire gamma spectrum--without rejecting any valid pulses. This timing resolution approaches the best obtained by analog nuclear electronics, without the corresponding complexities of analog optimization procedures. We further demonstrate the universality and efficacy of the machine learning approach by applying the method to the generation of secondary electron time-of-flight spectra following the implantation of energetic positrons on a sample.

   ↳ physics.ins-detcond-mat.mtrl-scics.LGhep-ex+2Nucl.Instrum.Meth.A(2020)·7 citations
7. 07*

   Deciphering the nature of X(3872) in heavy ion collisions

   Hui Zhang🇨🇳 · Jinfeng Liao🇺🇸 · Enke Wang🇨🇳 · Qian Wang🇨🇳 · Hongxi Xing🇨🇳

   Exploring the nature of exotic multiquark candidates such as the $X(3872)$ plays a pivotal role in understanding quantum chromodynamics (QCD). Despite significant efforts, consensus on their internal structures is still lacking. As a prime example, it remains a pressing open question to decipher the $X(3872)$ state between two popular exotic configurations: a loose hadronic molecule or a compact tetraquark. We demonstrate a novel approach to help address this problem by studying the $X(3872)$ production in heavy ion collisions, where a hot fireball with ample light as well as charm (anti-)quarks is available for producing the exotics. Adopting a multiphase transport model (AMPT) for describing such collisions and implementing appropriate production mechanism of either molecule or tetraquark picture, we compute and compare a series of observables for $X(3872)$ in Pb-Pb collisions at the Large Hadron Collider. We find the fireball volume plays a crucial role, leading to a 2-order-of-magnitude difference in the $X(3872)$ yield and a markedly different centrality dependence between hadronic molecules and compact tetraquarks, thus offering a unique opportunity for distinguishing the two scenarios. We also make the first prediction of $X(3872)$ elliptic flow coefficient to be tested by future experimental measurements.

   ↳ hep-phhep-exnucl-exnucl-thPRL(2021)·74 citations
8. 08*

   Extracting the jet transport coefficient of cold nuclear matter from world data

   Peng Ru🇨🇳 · Zhong-Bo Kang🇺🇸 · Enke Wang🇨🇳 · Hongxi Xing🇨🇳 · Ben-Wei Zhang🇨🇳

   We present the first global extraction of the jet transport coefficient ($\hat{q}$) for cold nuclear matter within the framework of higher-twist expansion. The analysis takes into account the world data on transverse momentum broadening in semi-inclusive $e$-A deep inelastic scattering (DIS) and in Drell-Yan dilepton and heavy quarkonium production in $p$-A collisions, as well as the nuclear modification of the structure functions in DIS. The results of this work provide the first quantitative evidence for the universality and non-trivial scale dependence of the medium transport property, similar to that for nucleon structure as encoded in the standard parton distribution functions. We expect the extracted scale dependence of $\hat{q}$ for cold nuclear matter can be extended to precisely identify the fundamental property of quark gluon plasma.

   ↳ nucl-thnucl-exNPA(2021)·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.