Fri·Feb 9, 2024Friday·February 9, 2024

1. 01*

   First measurement of the yield of ${}^8$He isotopes produced in liquid scintillator by cosmic-ray muons at Daya Bay

   Daya Bay Collaboration: F. P. An · W. D. Bai · A. B. Balantekin · M. Bishai · S. Blyth · G. F. Cao · J. Cao · J. F. Chang · Y. Chang · H. S. Chen · H. Y. Chen · S. M. Chen and 189 other authors

   Daya Bay presents the first measurement of cosmogenic ${}^8$He isotope production in liquid scintillator, using an innovative method for identifying cascade decays of ${}^8$He and its child isotope, ${}^8$Li. We also measure the production yield of ${}^9$Li isotopes using well-established methodology. The results, in units of 10${}^{-8}{\mu }^{-1}$g${}^{-1}$cm${}^2$, are 0.307$\pm$0.042, 0.341$\pm$0.040, and 0.546$\pm$0.076 for ${}^8$He, and 6.73$\pm$0.73, 6.75$\pm$0.70, and 13.74$\pm$0.82 for ${}^9$Li at average muon energies of 63.9~GeV, 64.7~GeV, and 143.0~GeV, respectively. The measured production rate of ${}^8$He isotopes is more than an order of magnitude lower than any other measurement of cosmogenic isotope production. It replaces the results of previous attempts to determine the ratio of ${}^8$He to ${}^9$Li production that yielded a wide range of limits from 0 to 30\%. The results provide future liquid-scintillator-based experiments with improved ability to predict cosmogenic backgrounds.

   nucl-exhep-exPRD(2024)·5 citations
2. 02*

   First measurement using elliptically polarized photons of the double-polarization observable $E$ for $\gamma p\to p{\pi }^0$ and $\gamma p\to n{\pi }^{+}$

   A2 Collaboration: F. Afzal🇩🇪 · K. Spieker🇩🇪 · P. Hurck🇬🇧 · S. Abt🇨🇭 · P. Achenbach🇩🇪 · P. Adlarson🇩🇪 · Z. Ahmed🇨🇦 · C.S. Akondi🇺🇸 · J.R.M. Annand🇬🇧 · H.J. Arends🇩🇪 · M. Bashkanov🇬🇧 · R. Beck🇩🇪 and 64 other authors

   We report the measurement of the helicity asymmetry $E$ for the $p{\pi }^0$ and $n{\pi }^{+}$ final states using, for the first time, an elliptically polarized photon beam in combination with a longitudinally polarized target at the Crystal Ball experiment at MAMI. The results agree very well with data that were taken with a circularly polarized photon beam, showing that it is possible to simultaneously measure polarization observables that require linearly (e.g.~$G$) and circularly polarized photons (e.g.~$E$) and a longitudinally polarized target. The new data cover a photon energy range 270 - 1400 MeV for the $p{\pi }^0$ final state (230 - 842 MeV for the $n{\pi }^{+}$ final state) and the full range of pion polar angles, $\theta$, providing the most precise measurement of the observable $E$. A moment analysis gives a clear observation of the $p\eta$ cusp in the $p{\pi }^0$ final state.

   nucl-exPRL(2024)·7 citations
3. 03*

   The unexpected uses of a bowling pin: exploiting ${}^{20}$Ne isotopes for precision characterizations of collectivity in small systems

   Giuliano Giacalone🇩🇪 · Benjamin Bally🇫🇷 · Govert Nijs🇨🇭 · Shihang Shen🇩🇪 · Thomas Duguet🇫🇷 · Jean-Paul Ebran🇫🇷 · Serdar Elhatisari🇹🇷 · Mikael Frosini🇫🇷 · Timo A. Lähde🇩🇪 · Dean Lee🇺🇸 · Bing-Nan Lu🇨🇳 · Yuan-Zhuo Ma🇺🇸 and 7 other authors

   Whether or not femto-scale droplets of quark-gluon plasma (QGP) are formed in so-called small systems at high-energy colliders is a pressing question in the phenomenology of the strong interaction. For proton-proton or proton-nucleus collisions the answer is inconclusive due to the large theoretical uncertainties plaguing the description of these processes. While upcoming data on collisions of ${}^{16}$O nuclei may mitigate these uncertainties in the near future, here we demonstrate the unique possibilities offered by complementing ${}^{16}$O${}^{16}$O data with collisions of ${}^{20}$Ne ions. We couple both NLEFT and PGCM ab initio descriptions of the structure of ${}^{20}$Ne and ${}^{16}$O to hydrodynamic simulations of ${}^{16}$O${}^{16}$O and ${}^{20}$Ne${}^{20}$Ne collisions at high energy. We isolate the imprints of the bowling-pin shape of ${}^{20}$Ne on the collective flow of hadrons, which can be used to perform quantitative tests of the hydrodynamic QGP paradigm. In particular, we predict that the elliptic flow of ${}^{20}$Ne${}^{20}$Ne collisions is enhanced by as much as 1.170(8)${}_{stat.}$(30)${}_{syst.}$ for NLEFT and 1.139(6)${}_{stat.}$(39)${}_{syst.}$ for PGCM relative to ${}^{16}$O${}^{16}$O collisions for the 1% most central events. At the same time, theoretical uncertainties largely cancel when studying relative variations of observables between two systems. This demonstrates a method based on experiments with two light-ion species for precision characterizations of the collective dynamics and its emergence in a small system.

   ↳ nucl-thhep-phnucl-exPRL(2025)·105 citations
4. 04*

   AI Assisted Experiment Control and Calibration

   Thomas Britton🇺🇸 · Michael Goodrich🇺🇸 · Naomi Jarvis🇺🇸 · Torri Jeske🇺🇸 · Nikhil Kalra🇺🇸 · David Lawrence🇺🇸 · Diana McSpadden🇺🇸

   Final report for the AI Assisted Experiment Control and Calibration project. This project integrated AI/ML into the controls and calibration of a production detector system in the GlueX spectrometer, a large scale Nuclear Physics detector in experimental Hall-D at Jefferson Lab. The AI/ML model predicted calibration constants for a Central Drift Chamber using environmental information available prior to taking the data. The device controls were then automatically adjusted so that the calibration values needed for post-processing of the data were much more stable and quicker to determine. Integration into a production system required guardrails and policy choices to ensure safety of the equipment and the data quality. The project sought to apply similar technology to other detectors. Those efforts are also described here. This documents many of the details of the project.

   ↳ physics.ins-detnucl-ex0 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.