Wed·Jan 25, 2023Wednesday·January 25, 2023

1. 01*

   Production of pions, kaons, and protons as a function of the relative transverse activity classifier in pp collisions at $\sqrt{s}=13$ TeV

   ALICE Collaboration

   The production of ${\pi }^{\pm }$, ${\mathrm{K}}^{\pm }$, and $(\overline{\mathrm{p}})$p is measured in pp collisions at $\sqrt{s}=13$ TeV in different topological regions. Particle transverse momentum ($p_{\mathrm{T}}$) spectra are measured in the ``toward'', ``transverse'', and ``away'' angular regions defined with respect to the direction of the leading particle in the event. While the toward and away regions contain the fragmentation products of the near-side and away-side jets, respectively, the transverse region is dominated by particles from the Underlying Event (UE). The relative transverse activity classifier, $R_{\mathrm{T}}=N_{\mathrm{T}}/⟨N_{\mathrm{T}}⟩$, is used to group events according to their UE activity, where $N_{\mathrm{T}}$ is the measured charged-particle multiplicity per event in the transverse region and $⟨N_{\mathrm{T}}⟩$ is the mean value over all the analysed events. The first measurements of identified particle $p_{\mathrm{T}}$ spectra as a function of $R_{\mathrm{T}}$ in the three topological regions are reported. The yield of high transverse momentum particles relative to the $R_{\mathrm{T}}$-integrated measurement decreases with increasing $R_{\mathrm{T}}$ in both the toward and away regions, indicating that the softer UE dominates particle production as $R_{\mathrm{T}}$ increases and validating that $R_{\mathrm{T}}$ can be used to control the magnitude of the UE. Conversely, the spectral shapes in the transverse region harden significantly with increasing $R_{\mathrm{T}}$. This hardening follows a mass ordering, being more significant for heavier particles. The $p_{\mathrm{T}}$-differential particle ratios $(\mathrm{p}+\overline{\mathrm{p}})/({\pi }^{+}+{\pi }^{-})$ and $({\mathrm{K}}^{+}+{\mathrm{K}}^{-})/({\pi }^{+}+{\pi }^{-})$ in the low UE limit $(R_{\mathrm{T}}\to 0)$ approach expectations from Monte Carlo generators such as PYTHIA 8 with Monash 2013 tune and EPOS LHC, where the jet-fragmentation models have been tuned to reproduce ${\mathrm{e}}^{+}{\mathrm{e}}^{-}$ results.

   nucl-exhep-exJHEP(2023)·22 citations
2. 02*

   Bayesian refinement of covariant energy density functionals

   Marc Salinas🇺🇸 · J. Piekarewicz🇺🇸

   The last five years have seen remarkable progress in our quest to determine the equation of state of neutron rich matter. Recent advances across the theoretical, experimental, and observational landscape have been incorporated in a Bayesian framework to refine existing covariant energy density functionals previously calibrated by the properties of finite nuclei. In particular, constraints on the maximum neutron star mass from pulsar timing, on stellar radii from the NICER mission, on tidal deformabilities from the LIGO-Virgo collaboration, and on the dynamics of pure neutron matter as predicted from chiral effective field theories, have resulted in significant refinements to the models, particularly to those predicting a stiff symmetry energy. Still, even after these improvements, we find challenging to reproduce simultaneously the neutron skin thickness of both ${}^{208}$Pb and ${}^{48}$Ca recently reported by the PREX/CREX collaboration.

   ↳ nucl-thastro-ph.SRnucl-exPRC(2023)·27 citations
3. 03*

   Response of germanium detectors for high-energy $\gamma$-rays by ${}^{27}$Al(p, $\gamma$)${}^{28}$Si at Ep=992 keV

   Rurie Mizuno🇯🇵 · Megumi Niikura🇯🇵 · Tokihiro Ikeda🇯🇵 · Teiichiro Matsuzaki🇯🇵 · Shintaro Go🇺🇸 · Takeshi Y. Saito · Shin'ichiro Michimasa🇯🇵 · Hiroyoshi Sakurai🇯🇵

   The performance of germanium detectors for high-energy $\gamma$-rays was evaluated using a 992-keV resonance in the ${}^{27}$Al(p, $\gamma$)${}^{27}$Si reaction. The measurement was conducted at the RIKEN tandem accelerator. The energy of the excited state from the resonance was evaluated as 12540.7(2) keV. Using newly evaluated excitation energy, an energy calibration function and the photo-peak efficiency of Ge detectors up to 10.8-MeV photon were deduced. The energy accuracy is achieved at 0.3 keV for the overall energy region. This reaction provides reliable energy and efficiency standards for high-energy $\gamma$ rays.

   ↳ physics.ins-detnucl-exPTEP(2023)·1 citation
4. 04*

   Production and measurement of stellar neutron spectrum at 30 keV

   Javier Praena · Guido Martín-Hernández · Javier García López

   In the present experiment we measure the forward-emitted angle-integrated neutron spectrum of the 7Li(p,n)7Be reaction via time-of-flight neutron spectrometry. The proton beam is shaped to a Gaussian-like distribution with energies close to the reaction threshold upstream the thick lithium target. The angle-integrated neutron spectrum resembles a Maxwellian or stellar neutron spectrum at kT=30 keV.

   ↳ physics.ins-detnucl-exEPJA(2024)·2 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.