Mon·Oct 7, 2024Monday·October 7, 2024

1. 01*

   Light Nuclei Femtoscopy and Baryon Interactions in 3 GeV Au+Au Collisions at RHIC

   The STAR Collaboration

   We report the measurements of proton-deuteron ($p$-$d$) and deuteron-deuteron ($d$-$d$) correlation functions in Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}$ = 3 GeV using fixed-target mode with the STAR experiment at the Relativistic Heavy-Ion Collider (RHIC). For the first time, the source size ($R_G$), scattering length ($f_0$), and effective range ($d_0$) are extracted from the measured correlation functions with a simultaneous fit. The spin-averaged $f_0$ for $p$-$d$ and $d$-$d$ interactions are determined to be -5.28 $\pm$ 0.11(stat.) $\pm$ 0.82(syst.) fm and -2.62 $\pm$ 0.02(stat.) $\pm$ 0.24(syst.) fm, respectively. The measured $p$-$d$ interaction is consistent with theoretical calculations and low-energy scattering experiment results, demonstrating the feasibility of extracting interaction parameters using the femtoscopy technique. The reasonable agreement between the experimental data and the calculations from the transport model indicates that deuteron production in these collisions is primarily governed by nucleon coalescence.

   nucl-exhep-exhep-phnucl-thPLB(2025)·21 citations
2. 02*

   A Method for Proton Detector Efficiency Measurement with Applications in Neutron Beta Decay and Lifetime Experiments

   Grant V. Riley🇺🇸 · Nadia Fomin🇺🇸 · Jaideep Taggart Singh🇺🇸 · William Greene · Rebecca Godri🇺🇸 · Evan Adamek · Eli Carter

   This article proposes a new method to measure the proton detector efficiency for use in "beam" determinations of the free neutron lifetime. There is currently a 4{\sigma} disagreement between the "beam" and "storage" methods of measuring the lifetime of the neutron. A possible reason for this is a systematic uncertainty that is not properly accounted for in one or both types of experiments. Absolute proton counting is an essential facet of the "beam" experimental approach. The absolute detector efficiency is not currently known for existing experiments and could be a source of a hidden systematic error. The proposed absolute calibration techniques can also be extended to new, large area particle detectors designed for future experiments. We propose to laser ionize a beam of atomic hydrogen and simultaneously count both the outgoing protons and electrons. Due to recent advances in UV laser and atomic hydrogen beam technologies, we estimate a count rate as high as ~200k proton-electrons pairs per second under the most favorable scheme discussed. Our proposed technique would remove one of the leading systematic uncertainties in the determination of the neutron lifetime, making an precision of {\pm}0.16 s feasible. Precise and accurate knowledge of the proton detection efficiency is crucial to fully understanding the systematics of the "beam" measurement method as well as developing next generation experiments that will have the precision to test the Standard Model.

   ↳ physics.ins-detnucl-exNucl.Instrum.Meth.A(2025)·0 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.