Wed·Oct 4, 2017Wednesday·October 4, 2017

1. 01*

   Fission Fragment Angular Anisotropy in Neutron-Induced Fission of ${}^{235}$U Measured with a Time Projection Chamber

   V. Geppert-Kleinrath🇺🇸 · F. Tovesson · J.S. Barrett🇺🇸 · N.S. Bowden🇺🇸 · J. Bundgaard🇺🇸 · R.J. Casperson🇺🇸 · D.A. Cebra🇺🇸 · T. Classen🇺🇸 · M. Cunningham🇺🇸 · D.L. Duke🇺🇸 · J. Gearhart🇺🇸 · U. Greife🇺🇸 and 24 other authors

   Fission fragment angular distributions can provide an important constraint on fission theory, improving predictive fission codes, and are a prerequisite for a precise ratio cross section measurement. Available anisotropy data is sparse, especially at neutron energies above 5 MeV. For the first time, a three-dimensional tracking detector is employed to study fragment emission angles and provide a direct measurement of angular anisotropy. The Neutron Induced Fission Fragment Tracking Experiment (NIFFTE) collaboration has deployed the fission time projection chamber (fissionTPC) to measure nuclear data with unprecedented precision. The fission fragment anisotropy of ${}^{235}$U has been measured over a wide range of incident neutron energies from 180 keV to 200 MeV; a careful study of the systematic uncertainties complement the data.

   nucl-exPRC(2019)·18 citations
2. 02*

   Exciting Nucleons in Compton Scattering and Hydrogen-Like Atoms

   Franziska Hagelstein (JGU Mainz)🇩🇪

   This PhD thesis is devoted to the low-energy structure of the nucleon (proton and neutron) as seen through electromagnetic probes, e.g., electron and Compton scattering. The research presented here is based primarily on dispersion theory and chiral effective-field theory. The main motivation is the recent proton radius puzzle, which is the discrepancy between the classic proton charge radius determinations (based on electron-proton scattering and normal hydrogen spectroscopy) and the highly precise extraction based on first muonic-hydrogen experiments by the CREMA Collaboration. The precision of muonic-hydrogen experiments is presently limited by the knowledge of proton structure effects beyond the charge radius. A major part of this thesis is devoted to calculating these effects using everything we know about the nucleon electromagnetic structure from both theory and experiment. The thesis consists of eight chapters. The first and last are, respectively, the introduction and conclusion. The remainder of this thesis can roughly be divided into the following three topics: finite-size effects in hydrogen-like atoms, real and virtual Compton scattering, and two-photon-exchange effects.

   ↳ nucl-thhep-phnucl-exphysics.atom-ph12 citations
3. 03*

   Dynamical initial state model for relativistic heavy-ion collisions

   Chun Shen🇺🇸 · Björn Schenke🇺🇸

   We present a fully three-dimensional model providing initial conditions for energy and net-baryon density distributions in heavy ion collisions at arbitrary collision energy. The model includes the dynamical deceleration of participating nucleons or valence quarks, depending on the implementation. The duration of the deceleration continues until the string spanned between colliding participants is assumed to thermalize, which is either after a fixed proper time, or a fluctuating time depending on sampled final rapidities. Energy is deposited in space-time along the string, which in general will span a range of space-time rapidities and proper times. We study various observables obtained directly from the initial state model, including net-baryon rapidity distributions, 2-particle rapidity correlations, as well as the rapidity decorrelation of the transverse geometry. Their dependence on the model implementation and parameter values is investigated. We also present the implementation of the model with 3+1 dimensional hydrodynamics, which involves the addition of source terms that deposit energy and net-baryon densities produced by the initial state model at proper times greater than the initial time for the hydrodynamic simulation.

   ↳ nucl-thhep-phnucl-exPRC(2018)·220 citations
4. 04*

   Event patterns extracted from anisotropic spectra of charged particles produced in Pb-Pb collisions at 2.76 TeV

   Ya-Hui Chen🇨🇳 · Fu-Hu Liu🇨🇳

   Event patterns extracted from anisotropic spectra of charged particles produced in lead-lead collisions at 2.76 TeV are investigated. We use an inverse power-law resulted from the QCD calculus to describe the transverse momentum spectrum in the hard scattering process, and a revised Erlang distribution resulted from a multisource thermal model to describe the transverse momentum spectrum and anisotropic flow in the soft excitation process. The pseudorapidity distribution is described by a three-Gaussian function which is a revision of the Landau hydrodynamic model. Thus, the event patterns at the kinetic freeze-out are displayed by the scatter plots of the considered particles in the three-dimensional velocity, momentum, and rapidity spaces.

   ↳ nucl-thhep-exhep-phnucl-exEPJA(2017)·4 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.