Thu·Feb 20, 2025Thursday·February 20, 2025

1. 01*

   A Comparative Analysis of R-Matrix Fitting: ${}^{12}$C$(p,\gamma )$${}^{13}$N as Test Case

   J. Skowronski🇮🇹 · D. Piatti · D. Rapagnani🇮🇹 · M. Aliotta🇩🇪 · C. Ananna🇮🇹 · L. Barbieri · F. Barile · D. Bemmerer🇩🇪 · A. Best🇮🇹 · A. Boeltzig🇩🇪 · C. Broggini🇮🇹 · C. G. Bruno🇬🇧 and 40 other authors

   In nuclear astrophysics, the accurate determination of nuclear reaction cross sections at astrophysical energies is critical for understanding stellar evolution and nucleosynthesis. This study focuses on the ${}^{12}$C($p,\gamma$)${}^{13}$N reaction, which takes part in the CNO cycle and is significant for determining the ${}^{12}$C/${}^{13}$C ratio in stellar interiors. Data from various studies, including recent LUNA measurements, reveal high discrepancies in cross section values, underscoring the need for robust fitting approaches. Utilizing the R-matrix theory, we compare different frequentist and Bayesian methodologies for estimating reaction cross sections and their uncertainties. The analysis evaluates the strengths and weaknesses of different statistical techniques, highlighting the importance of systematic uncertainty treatment and the estimate of covariance matrix estimation to enhance the reliability and reproducibility of uncertainty estimates in nuclear astrophysics.

   nucl-exPRC(2025)·3 citations
2. 02*

   Characterization Of MOSS For The ALICE ITS3 For The LHC Run 4

   Livia Terlizzi (on behalf of the ALICE Collaboration)🇮🇹

   ALICE, one of the four main CERN LHC experiments, studies heavy-ion collisions at ultra-relativistic energies. For LHC Run 4 (starting 2030), ALICE will replace the three innermost cylindrical layers of its inner tracking system during Long Shutdown 3 (2026-2029). The new ITS3 will enhance pointing resolution by a factor of two and improve tracking efficiency at low transverse momentum (pT < 0.3 GeV/c). It will feature ultra-thin (< 50 micrometer), stitched wafer-scale Monolithic Active Pixel Sensors (MAPS) using 65 nm CMOS imaging technology. These sensors can be bent, forming a truly cylindrical barrel with an innermost radius of 19 mm and an average material budget of 0.09 X/X0 per layer. ITS3 development involves cutting-edge R&D, including MAPS production in 65 nm CMOS, stitched wafer-scale fabrication, ultra-light mechanics, and a novel air cooling system. The 65 nm CMOS technology was validated using Multi-Layer Reticle 1 test structures. In mid-2023, the first stitched prototypes, MOnolithic Stitched Sensors (MOSS), were produced to demonstrate stitching feasibility and assess wafer-scale sensor yield and performance. Each MOSS chip (1.4 cm x 25.9 cm) contains 6.7 million pixels across 10 repeated sensor units, each with 8 pixel matrices: top matrices (256 x 256 pixels, 22.5 micrometer pitch) and bottom matrices (320 x 320 pixels, 18 micrometer pitch). These layouts help evaluate yield variations based on density and spacing. This work presents results from MOSS characterization, including power domain impedance, DAC performance, pixel readout, threshold, and fake-hit rate scans. Beam and lab tests confirmed an efficiency >99% and a Fake Hit Rate lower than 0.1 pixel-1 s-1, meeting ITS3 requirements for Run 4.

   ↳ physics.ins-dethep-exnucl-exJINST(2025)·5 citations
3. 03*

   Electromagnetic Radiation from High-Energy Nuclear Collisions

   Charles Gale🇨🇦

   We highlight some of the developments in the theory and the observation of the electromagnetic radiation, thermal and otherwise, emitted in relativistic heavy-ion collisions.

   ↳ nucl-thhep-phnucl-ex9 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.