Tue·May 5, 2020Tuesday·May 5, 2020

1. 01*

   Search for $\alpha$ decay of naturally occurring Hf-nuclides using a Cs${}_2$HfCl${}_6$ scintillator

   V. Caracciolo🇮🇹 · S. Nagorny🇨🇦 · P. Belli🇮🇹 · R. Bernabei🇮🇹 · F. Cappella🇮🇹 · R. Cerulli🇮🇹 · A. Incicchitti🇮🇹 · M. Laubenstein🇮🇹 · V. Merlo🇮🇹 · S. Nisi🇮🇹 · P. Wang🇨🇦

   Residual radioactive contaminants of a caesium hafnium chloride (Cs${}_2$HfCl${}_6$) crystal scintillator have been measured in a low background setup at the Gran Sasso National Laboratory of the INFN, Italy. The total alpha activity of the detector is at the level of 7.8(3) mBq/kg. The results of direct studies of the $\alpha$ decay of naturally occurring Hf isotopes that have been performed using the "source=detector" approach are presented. In 2848 h of data taking, the $\alpha$ decay of ${}^{174}$Hf was observed with T${}_{1/2}=(7.0\pm 1.2)\times 10^{16}$ y.

   nucl-exhep-exphysics.ins-detNPA(2020)·14 citations
2. 02*

   Results on Total and Elastic Cross Sections in Proton-Proton Collisions at $\sqrt{s}$ = 200 GeV Obtained with the STAR Detector at RHIC

   W. Guryn🇺🇸 · B. Pawlik (for the STAR Collaboration)🇵🇱

   We report the first results on differential, total and elastic cross sections in proton-proton collisions at the Relativistic Heavy Ion Collider (RHIC) at $\sqrt{s}=200$ GeV. The data lwere obtained with the Roman Pot Detector subsystem of the STAR experiment. The data used for this analysis cover the four-momentum transfer squared ~($t$) range $0.045\le |t|\le 0.135$ (GeV/c)${}^2$. The Roman Pot system was placed downstream of the STAR detector. During the data taking the Roman Pots were moved to ~8${\sigma }_y$, the vertical distance of from the beam center. They were operated during standard data taking procedure. The results include values of the exponential slope parameter (B), elastic cross section (${\sigma }_{el}$) and the total cross section (${\sigma }_{tot}$) obtained by extrapolation of the elastic differential cross section ($d\sigma /dt$) to the optical point at $|t|=0$ (GeV/c)${}^2$. The detector setup and analysis procedure are reviewed. All results are compared with the world data.

   ↳ hep-exnucl-ex2 citations
3. 03*

   Exclusive tensor meson photoproduction

   JPAC Collaboration: V. Mathieu🇪🇸 · A. Pilloni🇮🇹 · M. Albaladejo🇺🇸 · L. Bibrzycki🇵🇱 · A. Celentano🇮🇹 · C. Fernandez-Ramirez🇲🇽 · A.P. Szczepaniak🇺🇸

   We study tensor meson photoproduction outside of the resonance region, at beam energies of few GeVs. We build a model based on Regge theory that includes the leading vector and axial exchanges. We consider two determinations of the unknown helicity couplings, and fit to the recent a2 photoproduction data from CLAS. Both choices give a similar description of the a2 cross section, but result in different predictions for the parity asymmetries and the f2 photoproduction cross section. We conclude that new measurements of f2 photoproduction in the forward region are needed to pin down the correct production mechanism. We also extend our predictions to the 8.5 GeV beam energy, where current experiments are running.

   ↳ hep-phnucl-exnucl-thPRD(2020)·28 citations
4. 04*

   Extracing the number of short-range corerlated nucleon pairs from inclusive electron scattering data

   R. Weiss🇮🇱 · A.W. Denniston🇺🇸 · J.R. Pybus🇺🇸 · O. Hen🇺🇸 · E. Piasetzky🇮🇱 · A. Schmidt🇺🇸 · L.B. Weinstein🇺🇸 · N. Barnea🇮🇱

   The extraction of the relative abundances of short-range correlated (SRC) nucleon pairs from inclusive electron scattering is studied using the generalized contact formalism (GCF) with several nuclear interaction models. GCF calculations can reproduce the observed scaling of the cross-section ratios for nuclei relative to deuterium at high-$x_B$ and large-$Q^2$, $a_2=({\sigma }_A/A)/({\sigma }_d/2)$. In the non-relativistic instant-form formulation, the calculation is very sensitive to the model parameters and only reproduces the data using parameters that are inconsistent with ab-initio many-body calculations. Using a light-cone GCF formulation significantly decreases this sensitivity and improves the agreement with ab-initio calculations. The ratio of similar mass isotopes, such as ${}^{40}$Ca and ${}^{48}$Ca, should be sensitive to the nuclear asymmetry dependence of SRCs, but is found to also be sensitive to low-energy nuclear structure. Thus the empirical association of SRC pair abundances with the measured $a_2$ values is only accurate to about $20\%$. Improving this will require cross-section calculations that reproduce the data while properly accounting for both nuclear structure and relativistic effects.

   ↳ nucl-thnucl-exPRC(2021)·34 citations
5. 05*

   Plastic Scintillation Detectors for Time-of-Flight Mass Measurements

   Kailong Wang · Alfredo Estrade🇺🇸 · Shree Neupane · Miles Barber · Michael Famiano🇺🇸 · Tom Ginter · David McClain · Neerajan Nepal🇺🇸 · Jorge Pereira · Hendrik Schatz🇺🇸 · George Zimba🇿🇦

   Fast timing detectors are an essential element in the experimental setup for time-of-flight (ToF) mass measurements of unstable nuclei. We have upgraded the scintillator detectors used in experiments at the National Superconducting Cyclotron Laboratory (NSCL) by increasing the number of photomultiplier tubes that read out their light signals to four per detector, and characterized them in a test experiment with ${}^{48}$Ca beam at the NSCL. The new detectors achieved a time resolution ($\sigma$) of 7.5 ps. We systematically investigated different factors that affect their timing performance. In addition, we evaluated the ability of positioning the hitting points on the scintillator using the timing information and obtained a resolution ($\sigma$) below 1 mm for well-defined beam spots.

   ↳ physics.ins-detnucl-exNucl.Instrum.Meth.A(2020)·6 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.