Nuclear Experiment·nucl-ex
11 papers—0 primary·11 cross-listed·reconstructed*
I summarize our recent work towards finding and utilizing analytic solutions of relativistic hydrodynamic. In the first part I discuss various exact solutions of the second-order conformal hydrodynamics. In the second part I compute flow harmonics analytically using the anisotropically deformed Gubser flow and discuss its dependence on , , viscosity, the chemical potential and the charge.
D. Attie🇫🇷 · S. Barsuk🇫🇷 · O. Bezshyyko🇺🇦 · L. Burmistrov🇫🇷 · A. Chaus🇫🇷 · P. Colas🇫🇷 · O. Fedorchuk🇺🇦 · L. Golinka-Bezshyyko🇺🇦 · I. Kadenko🇺🇦 · V. Krylov🇫🇷 · V. Kubytskyi🇫🇷 · R. Lopez🇨🇭 and 5 other authors
A new versatile facility LEETECH for detector R&D, tests and calibration is designed and constructed. It uses electrons produced by the photoinjector PHIL at LAL, Orsay and provides a powerful tool for wide range R&D studies of different detector concepts delivering "mono-chromatic" samples of low energy electrons with adjustable energy and intensity. Among other innovative instrumentation techniques, LEETECH will be used for testing various gaseous tracking detectors and studying new Micromegas/InGrid concept which has very promising characteristics of spatial resolution and can be a good candidate for particle tracking and identification. In this paper the importance and expected characteristics of such facility based on detailed simulation studies are addressed.
Valery Kubarovsky (Jefferson Lab) (for the CLAS Collaboration)🇺🇸
The cross section of the exclusive and electroproduction reaction was measured at Jefferson Lab with a 5.75-GeV electron beam and the CLAS detector. Differential cross sections and structure functions and as functions of were obtained over a wide range of and . The data are compared with the GPD based theoretical models. Analyses find that a large dominance of transverse processes is necessary to explain the experimental results. Generalized form factors of the transversity GPDs and were directly extracted from the experimental observables for the first time. It was found that GPD dominates in pseudoscalar meson production. The combined and data opens the way for the flavor decomposition of the transversity GPDs. The first ever evaluation of this decomposition was demonstrated.
Shiori Takeuchi🇯🇵 · Koichi Murase🇯🇵 · Tetsufumi Hirano🇯🇵 · Pasi Huovinen🇩🇪 · Yasushi Nara🇯🇵
We study effects of the hadronic rescattering on final observables especially for multi-strange hadrons such as , and in high-energy heavy-ion collisions within an integrated dynamical approach. In this approach, (3+1)-dimensional ideal hydrodynamics is combined with a microscopic transport model, JAM. We simulate the collisions with or without hadronic rescatterings and compare observables between these two options so that we quantify the effects of the hadronic rescattering. We find that the mean transverse momentum and the elliptic flow parameter of multi-strange hadrons are less affected by hadronic rescattering and, as a result, the mass ordering of the -differential elliptic flow parameter is violated: At the RHIC and the LHC energies the for -mesons is larger than that for protons in the low- regions.
Taesoo Song🇩🇪 · Hamza Berrehrah🇩🇪
We study the hadronization time of heavy quark in nuclear matter by using the coalescence model and the spatial diffusion constant of heavy quark from lattice Quantum Chromodynamic calculations, assuming that the main interaction of heavy quark at the critical temperature is hadronization. It is found that the hadronization time of heavy quark is about 3 fm/c for , if a heavy quark is combined with the nearest light antiquark in coordinate space without any correlation between momentum of heavy quark and that of light antiquark which form a heavy meson. However, the hadronization time reduces to 0.6-1.2 fm/c for charm and 0.4-0.9 fm/c for bottom, depending on heavy meson radius, in the presence of momentum correlation. Considering the interspace between quarks and antiquarks at the critical temperature, it seems that the hadronization of heavy quark does not happen instantaneously but gradually for a considerable time, if started from the thermal distribution of quarks and antiquarks.
S. K. Prasad (for the ALICE Collaboration)🇮🇳
We present a systematic study of jet measurements in pp, p--Pb and Pb--Pb collisions using the ALICE detector at the LHC. Jet production cross sections are measured in pp collisions at = 2.76 and 7~TeV, in p--Pb collisions at = 5.02~TeV and in Pb--Pb collisions at = 2.76~TeV. Jet shape observables and fragmentation distributions are measured in pp collisions at 7~TeV. Jets are reconstructed at midrapidity in a wide range of transverse momentum using sequential recombination jet finding algorithms (, anti-, and SISCone) with several values of jet resolution parameter in the range 0.2 -- 0.6. Measurements are compared to Next-to-Leading Order (NLO) perturbative Quantum Chromodynamics (pQCD) calculations and predictions from Monte Carlo (MC) event generators such as PYTHIA, PHOJET and HERWIG. Jet production cross sections are well reproduced by NLO pQCD calculations in pp collisions at ~=~2.76~TeV. MC models could not explain the jet cross sections in pp collisions at = 7 TeV, whereas jet shapes and fragmentation distributions are rather well reproduced by these models. The jet nuclear modification factor in p--Pb collisions is found to be consistent with unity indicating the absence of large modifications of the initial parton distribution or strong final state effects on jet production, whereas a large jet suppression is observed in Pb--Pb central events with respect to peripheral events indicating formation of a dense medium in central Pb--Pb events.
Moeki Miyatani🇯🇵 · Natsumi Ikeno🇯🇵 · Hideko Nagahiro🇯🇵 · Satoru Hirenzaki🇯🇵
We have investigated the 6Li(gamma, d) reaction theoretically for the formation of the eta'(958) mesic nucleus. We have reported the numerical results in this article.
P. Žugec🇭🇷 · C. Weiß🇨🇭 · C. Guerrero🇪🇸 · F. Gunsing🇫🇷 · V. Vlachoudis🇨🇭 · M. Sabate-Gilarte🇨🇭 · A. Stamatopoulos🇬🇷 · T. Wright🇬🇧 · J. Lerendegui-Marco🇪🇸 · F. Mingrone🇮🇹 · J. A. Ryan🇬🇧 · S. G. Warren🇬🇧 · A. Tsinganis🇨🇭 · M. Barbagallo🇮🇹
A pulse shape analysis framework is described, which was developed for n_TOF-Phase3, the third phase in the operation of the n_TOF facility at CERN. The most notable feature of this new framework is the adoption of generic pulse shape analysis routines, characterized by a minimal number of explicit assumptions about the nature of pulses. The aim of these routines is to be applicable to a wide variety of detectors, thus facilitating the introduction of the new detectors or types of detectors into the analysis framework. The operational details of the routines are suited to the specific requirements of particular detectors by adjusting the set of external input parameters. Pulse recognition, baseline calculation and the pulse shape fitting procedure are described. Special emphasis is put on their computational efficiency, since the most basic implementations of these conceptually simple methods are often computationally inefficient.
The correlation between the transverse momentum and the azimuthal asymmetry the flow is studied. A correlation coefficient is defined between the average transverse momentum of hadrons emitted in an event and the square of the elliptic or triangular flow coefficient. The hydrodynamic model predicts a positive correlation of the transverse momentum with the elliptic flow, and almost no correlation with the triangular flow in Pb-Pb collisions at LHC energies. In p-Pb collisions the new correlation observable is very sensitive to the mechanism of energy deposition in the first stage of the collision.
S. Lipschutz🇬🇧 · R.G.T. Zegers🇺🇸 · J. Hill🇺🇸 · S. N. Liddick🇺🇸 · S. Noji🇺🇸 · C. J. Prokop🇺🇸 · M. Scott🇨🇦 · M. Solt🇺🇸 · C. Sullivan · J. Tompkins
A digital data acquisition system (DDAS) has been implemented for the Low Energy Neutron Detector Array (LENDA). LENDA is an array of 24 BC-408 plastic-scintillator bars designed to measure low-energy neutrons with kinetic energies in the range of 100 keV to 10 MeV from (p,n)-type charge-exchange reactions. Compared to the previous data acquisition (DAQ) system for LENDA, DDAS offers the possibility to lower the neutron detection threshold, increase the overall neutron-detection efficiency, decrease the dead time of the system, and allow for easy expansion of the array. The system utilized in this work was XIA's Digital Gamma Finder Pixie-16 250 MHz digitizers. A detector-limited timing resolution of 400 ps was achieved for a single LENDA bar. Using DDAS, the neutron detection threshold of the system was reduced compared to the previous analog system, now reaching below 100 keV. The new DAQ system was successfully used in a recent charge-exchange experiment using the C(p,n) reaction at the National Superconducting Cyclotron Laboratory (NSCL).
Tobias P. Reinhardt🇩🇪 · Stefan Gohl🇩🇪 · Stefan Reinicke🇩🇪 · Daniel Bemmerer🇩🇪 · Thomas E. Cowan🇩🇪 · Klaus Heidel🇩🇪 · Marko Röder🇩🇪 · Daniel Stach🇩🇪 · Andreas Wagner🇩🇪 · David Weinberger🇩🇪 · Kai Zuber (for the R3B collaboration)🇩🇪
The detection of 200-1000 MeV neutrons requires large amounts, 100 cm, of detector material because of the long nuclear interaction length of these particles. In the example of the NeuLAND neutron time-of-flight detector at FAIR, this is accomplished by using 3000 monolithic scintillator bars of 27055 cm size made of a fast plastic. Each bar is read out on the two long ends, and the needed time resolution of 150 ps is reached with fast timing photomultipliers. In the present work, it is investigated whether silicon photomultiplier (SiPM) photosensors can be used instead. Experiments with a picosecond laser system were conducted to determine the timing response of the assembly made up of SiPM and preamplifier. The response of the full system including also the scintillator was studied using 30 MeV single electrons provided by the ELBE superconducting electron linac. The ELBE data were matched by a simple Monte Carlo simulation, and they were found to obey an inverse-square-root scaling law. In the electron beam tests, a time resolution of = 136 ps was reached with a pure SiPM readout, well within the design parameters for NeuLAND.
* 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.