Wed·Aug 14, 2019Wednesday·August 14, 2019

1. 01*

   Measurement of $\varphi$ meson production in p+p interactions at 40, 80 and 158 GeV/c with the NA61/SHINE spectrometer at the CERN SPS

   NA61/SHINE Collaboration: A. Aduszkiewicz🇵🇱 · E.V. Andronov🇷🇺 · T. Antićić🇭🇷 · V. Babkin🇷🇺 · M. Baszczyk🇵🇱 · S. Bhosale🇵🇱 · A. Blondel🇨🇭 · M. Bogomilov🇧🇬 · A. Brandin🇷🇺 · A. Bravar🇨🇭 · W. Bryliński🇵🇱 · J. Brzychczyk🇵🇱 and 132 other authors

   Results on $\varphi$ meson production in inelastic p+p collisions at CERN SPS energies are presented. They are derived from data collected by the NA61/SHINE fixed target experiment, by means of invariant mass spectra fits in the $\varphi \to K^{+}{K}^{-}$ decay channel. They include the first ever measured double differential spectra of $\varphi$ mesons as a function of rapidity $y$ and transverse momentum $p_T$ for proton beam momenta of 80 GeV/c and 158 GeV/c, as well as single differential spectra of $y$ or $p_T$ for beam momentum of 40 GeV/c. The corresponding total $\varphi$ yields per inelastic p+p event are obtained. These results are compared with existing data on $\varphi$ meson production in p+p collisions. The comparison shows consistency but superior accuracy of the present measurements. The emission of $\varphi$ mesons in p+p reactions is confronted with that occurring in Pb+Pb collisions, and the experimental results are compared with model predictions. It appears that none of the considered models can properly describe all the experimental observables.

   nucl-exhep-exEPJC(2020)·25 citations
2. 02*

   Improved determination of the $\beta$-${\overline{\nu }}_e$ angular correlation coefficient $a$ in free neutron decay with the $a$SPECT spectrometer

   M. Beck🇩🇪 · F. Ayala Guardia🇩🇪 · S. Baeßler🇺🇸 · M. Borg🇩🇪 · F. Glück🇩🇪 · W. Heil🇩🇪 · J. Kahlenberg🇩🇪 · M. Klopf🇦🇹 · G. Konrad🇦🇹 · R. Maisonobe🇫🇷 · R. Muñoz Horta🇩🇪 · C. Schmidt🇩🇪 and 6 other authors

   We report on a precise measurement of the electron-antineutrino angular correlation ($a$ coefficient) in free neutron beta-decay from the $a$SPECT experiment. The $a$ coefficient is inferred from the recoil energy spectrum of the protons which are detected in 4$\pi$ by the $a$SPECT spectrometer using magnetic adiabatic collimation with an electrostatic filter. Data are presented from a 100 days run at the Institut Laue Langevin in 2013. The sources of systematic errors are considered and included in the final result. We obtain $a=-0.10430(84)$ which is the most precise measurement of the neutron $a$ coefficient to date. From this, the ratio of axial-vector to vector coupling constants is derived giving $|\lambda |=1.2677(28)$.

   nucl-exPRC(2020)·68 citations
3. 03*

   Positron Annihilation Lifetime Spectroscopy Using Fast Scintillators and Digital Electronics

   Ming Fang · Nathan Bartholomew · Angela Di Fulvio🇮🇹

   Positron Annihilation Lifetime Spectroscopy (PALS) is a non-destructive radiological technique widely used in material science studies. PALS typically relies on an analog coincidence measurement setup and allows the estimate of the positron lifetime in a material sample under investigation. The positronium trapping at vacancies in the material results in an increased lifetime. In this work, we have developed and optimized a PALS experimental setup using organic scintillators, fast digitizers, and advanced pulse processing algorithms. We tested three pairs of different organic scintillation detectors: EJ-309 liquid, EJ-276 newly developed plastic, and BC-418 plastic, and optimized the data processing parameters for each pair separately. Our high-throughput data analysis method is based on single-pulse interpolation and a constant fraction discrimination (CFD) algorithm. The setup based on the BC-418 detector achieved the best time resolution of 198.3 +- 0.8 ps. We used such optimized setup to analyze two single-crystal quartz samples and found lifetimes of 156 +- 9 ps and 366 +- 22 ps, in good agreement with the characteristic time constants of this material. The proposed experimental set up achieve an excellent time resolution, which makes it possible to accurately characterize material vacancies by discriminating between the lifetimes of either the spin singlet or triplet states of positronium. The optimized data processing algorithms are relevant to all the applications where fast timing is important, such as nuclear medicine and radiation imaging.

   ↳ physics.ins-detnucl-exphysics.data-anNucl.Instrum.Meth.A(2019)·5 citations
4. 04*

   Setting nonperturbative uncertainties on finite-temperature properties of neutron matter

   Arianna Carbone🇩🇪

   We present an error band on neutron matter properties at finite temperature (finite-T) which comprehends uncertainties on the nuclear interaction, the many-body method convergence, and the thermodynamical consistency of the approach. This study provides nonperturbative predictions for finite-T neutron matter employing chiral interactions which are selected on the basis of their performance in both finite nuclei and infinite matter at zero temperature. Since proper theoretical uncertainties at finite-T are still generally lacking, the band provided here represents a first step towards setting first-principles constraints on thermal aspects of the nuclear matter equation of state.

   ↳ nucl-thastro-ph.HEgr-qcnucl-exPRResearch(2020)·22 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.