Fri·Jul 28, 2017Friday·July 28, 2017

1. 01*

   Polarization Transfer Observables in Elastic Electron Proton Scattering at $Q^2=$2.5, 5.2, 6.8, and 8.5 GeV${}^2$

   A. J. R. Puckett🇺🇸 · E. J. Brash🇺🇸 · M. K. Jones🇺🇸 · W. Luo🇨🇳 · M. Meziane🇺🇸 · L. Pentchev🇺🇸 · C. F. Perdrisat🇺🇸 · V. Punjabi🇺🇸 · F. R. Wesselmann🇺🇸 · A. Afanasev🇺🇸 · A. Ahmidouch🇺🇸 · I. Albayrak🇺🇸 and 95 other authors

   The GEp-III and GEp-2$\gamma$ experiments were carried out in Jefferson Lab's (JLab's) Hall C from 2007-2008, to extend the knowledge of $G_E^p/G_M^p$ to the highest practically achievable $Q^2$ and to search for effects beyond the Born approximation in polarization transfer observables of elastic $\vec{e}p$ scattering. This article reports an expanded description of the common experimental apparatus and data analysis procedure, and the results of a final reanalysis of the data from both experiments, including the previously unpublished results of the full-acceptance data of the GEp-2$\gamma$ experiment. The Hall C High Momentum Spectrometer detected and measured the polarization of protons recoiling elastically from collisions of JLab's polarized electron beam with a liquid hydrogen target. A large-acceptance electromagnetic calorimeter detected the elastically scattered electrons in coincidence to suppress inelastic backgrounds. The final GEp-III data are largely unchanged relative to the originally published results. The statistical uncertainties of the final GEp-2$\gamma$ data are significantly reduced at $ϵ=0.632$ and $0.783$ relative to the original publication. The decrease with $Q^2$ of $G_E^p/G_M^p$ continues to $Q^2=8.5$ GeV${}^2$, but at a slowing rate relative to the approximately linear decrease observed in earlier Hall A measurements. At $Q^2=2.5$ GeV${}^2$, the proton form factor ratio $G_E^p/G_M^p$ shows no statistically significant $ϵ$-dependence, as expected in the Born approximation. The ratio $P_{\ell }/P_{\ell }^{Born}$ of the longitudinal polarization transfer component to its Born value shows an enhancement of roughly 1.4\% at $ϵ=0.783$ relative to $ϵ=0.149$, with $\approx 1.9\sigma$ significance based on the total uncertainty, implying a similar effect in the transverse component $P_t$ that cancels in the ratio $R$.

   nucl-exhep-exPRC(2017)·114 citations
2. 02*

   Evaluation of fusion-evaporation cross-section calculations

   B. Blank🇫🇷 · G. Canchel🇫🇷 · F. Seis🇫🇷 · P. Delahaye🇫🇷

   Calculated fusion-evaporation cross sections from five different codes are compared to experimental data. The present comparison extents over a large range of nuclei and isotopic chains to investigate the evolution of experimental and calculated cross sections. All models more or less overestimate the experimental cross sections. We found reasonable agreement by using the geometrical average of the five model calculations and dividing the average by a factor of 11.2. More refined analyses are made for example for the 100Sn region.

   nucl-exNucl.Instrum.Meth.B(2018)·13 citations
3. 03*

   Search for Neutrinoless Double-Beta Decay with the Upgraded EXO-200 Detector

   J.B. Albert🇺🇸 · G. Anton🇩🇪 · I. Badhrees🇺🇸 · P.S. Barbeau🇺🇸 · R. Bayerlein🇩🇪 · D. Beck🇺🇸 · V. Belov🇷🇺 · M. Breidenbach🇺🇸 · T. Brunner🇨🇦 · G.F. Cao🇨🇳 · W.R. Cen🇨🇳 · C. Chambers🇺🇸 and 81 other authors

   Results from a search for neutrinoless double-beta decay $0\nu \beta \beta$ of ${}^{136}$Xe are presented using the first year of data taken with the upgraded EXO-200 detector. Relative to previous searches by EXO-200, the energy resolution of the detector has been improved to $\sigma /E$=1.23%, the electric field in the drift region has been raised by 50%, and a system to suppress radon in the volume between the cryostat and lead shielding has been implemented. In addition, analysis techniques that improve topological discrimination between $0\nu \beta \beta$ and background events have been developed. Incorporating these hardware and analysis improvements, the median 90% confidence level $0\nu \beta \beta$ half-life sensitivity after combining with the full data set acquired before the upgrade has increased 2-fold to $3.7\times 10^{25}$ yr. No statistically significant evidence for $0\nu \beta \beta$ is observed, leading to a lower limit on the $0\nu \beta \beta$ half-life of $1.8\times 10^{25}$ yr at the 90% confidence level.

   ↳ hep-exnucl-exPRL(2018)·273 citations
4. 04*

   Improving isotopic identification with \emph{INDRA} Silicon-CsI(\emph{Tl}) telescopes

   O. Lopez🇫🇷 · M. Parlog🇫🇷 · B. Borderie🇫🇷 · M.F. Rivet🇫🇷 · G. Lehaut🇫🇷 · G. Tabacaru🇫🇷 · L. Tassan-got🇫🇷 · P. Pawlowski🇵🇱 · E. Bonnet🇫🇷 · R. Bougault🇫🇷 · A. Chbihi🇫🇷 · D. Dell'Aquila🇫🇷 and 12 other authors

   Profiting from previous works done with the \emph{INDRA} multidetector on the description of the light response $\mathcal{L}$ of the CsI(\emph{Tl}) crystals to different impinging nuclei, we propose an improved $\Delta E-\mathcal{L}$ identification-calibration procedure for Silicon-Cesium Iodide (Si-CsI) telescopes, namely an Advanced Mass Estimate (\emph{AME}) method. \emph{AME} is compared to the usual, %$"\Delta E-E"$ simple visual analysis of the corresponding two-dimensional map of $\Delta E-E$ type, by using \emph{INDRA} experimental data from nuclear reactions induced by heavy ions in the Fermi energy regime. We show that the capability of such telescopes to identify both the atomic $Z$ and the mass $A$ numbers of light and heavy reaction products, can be quantitatively improved thanks to the proposed approach. This conclusion opens new possibilities to use \emph{INDRA} for studying these reactions especially with radioactive beams. Indeed, the determination of the mass for charged reaction products becomes of paramount importance to shed light on the role of the isospin degree of freedom in the nuclear equation of state.

   ↳ physics.ins-detnucl-exNucl.Instrum.Meth.A(2018)·9 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.