Thu·Aug 23, 2018Thursday·August 23, 2018

1. 01*

   Improved Comparison of Measurements and Calculations of $\hat{q}L$ via transverse momentum broadening in Relativistic Heavy Ion Collisions using di-hadron correlations

   M. J. Tannenbaum🇺🇸

   The renewed interest in analyzing RHIC data on di-hadron correlations as probes of final state transverse momentum broadening as shown at Quark Matter 2018[1] by theoretical calculations[6] compared to experimental measurements[4,5] led me to review the quoted theoretical calculations and experimental measurements because the theoretical calculation[6] does not show the PHENIX measurements[4] as published. The above references were checked and fits were performed to the published measurements[4,7] to determine $\hat{q}L$ from the measured azimuthal broadening to compare with the theoretical calculation[6]. The new results will be presented in addition to some corrections to the previous work[3]. The measured values of $\hat{q}L$ show the interesting effect of being consistent with zero for larger values of associated $p_{Ta}\ge 3$ GeV/c which is shown to be related to well known measurements of the ratio of the Au+Au to p+p associated $p_{Ta}$ distributions for a given trigger $p_{Tt}$ called $I_{AA}$[23,25]. Di-jets rather than di-hadrons are proposed as an improved azimuthal broadening measurement to determine $\hat{q}L$ and possibly $\hat{q}$.

   nucl-ex0 citations
2. 02*

   A Simultaneous Description of Hadron and Jet Suppression in Heavy Ion Collisions

   Jorge Casalderrey-Solana🇪🇸 · Zachary Hulcher🇬🇧 · Guilherme Milhano🇵🇹 · Daniel Pablos🇨🇦 · Krishna Rajagopal🇺🇸

   We present a global fit to all data on the suppression of high energy jets and high energy hadrons in the most central heavy ion collisions at the LHC for two different collision energies, within a hybrid strong/weak coupling quenching model. Even though the measured suppression factors for hadrons and jets differ significantly from one another and appear to asymptote to different values in the high energy limit, we obtain a simultaneous description of all these data after constraining the value of a single model parameter. We use our model to investigate the origin of the difference between the observed suppression of jets and hadrons and relate it, quantitatively, to the observed modification of the jet fragmentation function in jets that have been modified by passage through the medium produced in heavy ion collisions. In particular, the observed increase in the fraction of hard fragments in medium-modified jets, which indicates that jets with the fewest hardest fragments lose the least energy, corresponds quantitatively to the observed difference between the suppression of hadrons and jets. We argue that a harder fragmentation pattern for jets with a given energy after quenching is a generic feature of any mechanism for the interaction between jets and the medium that they traverse that yields a larger suppression for wider jets. We also compare the results of our global fit to LHC data to measurements of the suppression of high energy hadrons in RHIC collisions, and find that with its parameter chosen to fit the LHC data our model is inconsistent with the RHIC data at the $3\sigma$ level, suggesting that hard probes interact more strongly with the less hot quark-gluon plasma produced at RHIC.

   ↳ hep-phnucl-exnucl-thPRC(2019)·72 citations
3. 03*

   Sub-micrometer resolution neutron tomography

   B. Heacock🇺🇸 · D. Sarenac🇨🇦 · D. G. Cory🇨🇦 · M. G. Huber · J. P. W. MacLean · H. Miao · H. Wen · D. A. Pushin🇨🇦

   We demonstrate a neutron tomography technique with sub-micrometer spatial resolution. Our method consists of measuring neutron diffraction spectra using a double crystal diffractometer as a function of sample rotation and then using a phase retrieval algorithm followed by tomographic reconstruction to generate a density map of the sample. In this first demonstration, silicon phase-gratings are used as samples, the periodic structure of which allows the shape of the gratings to be imaged without the need of position sensitive detectors. Topological features found in the reconstructions also appear in scanning electron micrographs. The reconstructions have a resolution of about 300 nm, which is over an order of magnitude smaller than the resolution of radiographic, phase contrast, differential phase contrast, and dark field neutron tomography methods. Further optimization of the underlying phase recovery and tomographic reconstruction algorithm is also considered.

   ↳ physics.ins-detnucl-ex4 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.