Wed·Jan 15, 2025Wednesday·January 15, 2025

1. 01*

   Photoneutron reactions on gold in the giant dipole resonance region: reaction cross sections and average kinetic energies of $(\gamma ,xn)$ photoneutrons

   I. Gheorghe · T. Ari-izumi · S. Goriely🇧🇪 · D. Filipescu · S. Belyshev · K. Stopani · H. Wang🇯🇵 · G. Fan · H. Scheit🇩🇪 · D. Symochko🇩🇪 · M. Krzysiek · T. Renstrøm and 3 other authors

   In this work, we present new data on the ${}^{197}$Au photoneutron reactions in and above the giant dipole resonance region, obtained by using 8 to 39~MeV quasi-monochromatic $\gamma$-ray beams produced at the NewSUBARU facility in Japan and a high-and-flat efficiency neutron detection system. We report absolute cross sections and mean photoneutron energies for the ${}^{197}$Au$(\gamma ,inX)$ reactions with $i$~=~1 to 4. The photoabsorption cross section was obtained as the sum of the $(\gamma ,inX)$ reaction cross sections. The giant dipole resonance parameter values were obtained by fitting the experimental photoabsorption cross sections. The present photoabsorption cross sections are in good agreement with the Saclay results of Veyssiere~\emph{et al.}. Thus, our study does not support the recommendation of Berman~\emph{et al.} of lowering the Saclay photoabsorption cross sections by 8$\%$. We observed a non-statistical high-energy neutron emission in the $(\gamma ,n)$ reaction in the low-energy region between $S_n$ and 10~MeV. The present results are compared with data from the literature and statistical model calculations performed with the TALYS and EMPIRE codes.

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

   Diffractive Physics Program at the Electron-Ion Collider's (EIC) 2nd Detector

   Jihee Kim🇺🇸

   The Electron-Ion Collider (EIC) will be a novel experimental facility to explore the properties of gluons in nucleons and nuclei, shedding light on their structure and dynamics. The EIC community outlined the physics program of the EIC in a White Paper, and the demanding detector requirements and potential technologies to deploy at an EIC detector were published in a comprehensive Yellow Report. The general-purpose detector resulting from this efforts, ePIC, is designed to perform a broad physics program. At the same time, the wider EIC community is strongly in favor of a second detector at the EIC. Having two general-purpose collider detectors to support the EIC science program, allows us to have cross-checks and control of systematic uncertainties for potential scientific discoveries. The second detector should feature complementary technologies where possible. It can also focus on specific measurements that are less well addressed by ePIC. The second interaction region provides potentially improved forward detector acceptance at low $p_T$ and a secondary beam focus that enables to enhance the exclusive, tagging, and diffractive physics program. Hereby, I will present potential capabilities of the second detector and discuss studies related to its diffractive physics program.

   nucl-exActa Phys.Polon.Supp.(2025)·2 citations
3. 03*

   Quarkonia and Deconfined Quark-Gluon Matter in Heavy-Ion Collisions

   A. Andronic🇩🇪 · R. Arnaldi🇮🇹

   In this report, we present an experimental overview of quarkonium results obtained in nucleus-nucleus collisions, with a focus on the data collected at the LHC. We discuss the current understanding of charmonium and bottomonium behavior in the deconfined medium produced in such collisions, comparing the various observables now accessible to state-of-the-art theoretical models. We also discuss the open points and how future heavy-ion experiments aim to clarify these aspects.

   nucl-exnucl-thAnn.Rev.Nucl.Part.Sci.(2025)·17 citations
4. 04*

   Proton halo structures and 22Al

   Panagiota Papakonstantinou🇰🇷 · Myeonghwan Mun🇰🇷 · Cong Pan🇨🇳 · Kaiyuan Zhang🇩🇪

   Inspired by the recent debate as to whether the proton drip-line nucleus 22Al demonstrates a halo structure in its ground state and in order to assess such a possibility, we have analyzed theoretical results obtained within the relativistic density functional theory in 22Al and in a number of neighboring nuclei especially along isotopic, isotonic, and isobaric chains. The theory includes self-consistently the effects of pairing, deformation and the continuum. We employ two different functional parameterizations, PC-F1 and PC-PK1. Although the valence proton of the 22Al nucleus is found very loosely bound, in concordance with experimental data, its spatial distribution is found to hardly penetrate the potential barrier. Its wave function is found to consist predominately of l=2 components, for which halo formation is disfavored. Comparisons with results for isobars reveal a somewhat more extended density distribution than that of the stable or neutron-rich counterparts, but comparisons along isotopic, isotonic, and isobaric chains reveal no discontinuities in size evolution, which, if present, might have signaled exotic structures.

   ↳ nucl-thnucl-exPRC(2025)·14 citations
5. 05*

   Compact pulsed laser deposition system for in-situ polarized neutron reflectometry

   Grigorii Kirichuk🇷🇺 · Alexey Grunin🇷🇺 · Artur Dolgoborodov🇩🇪 · Pavel Prokopovich🇷🇺 · Petr Shvets🇷🇺 · Alexey Vorobiev🇸🇪 · Anton Devishvilli🇫🇷 · Alexandr Goikhman🇺🇬 · Ksenia Maksimova🇩🇪

   The development of ferromagnet/heavy metal thin-film structures, such as CoFeB/Mo, with spin-orbit interaction requires advanced methods for their production and study. Polarized neutron reflectometry (PNR) provides unique insights into the evolution of magnetic properties, especially when applied in-situ during the growth process. Pulsed laser deposition (PLD) is a versatile method for producing magnetic thin films, and combining PLD with in-situ PNR measurements offers new possibilities for their investigation. In this work, we developed a compact vacuum chamber integrated into the neutron instrument, enabling step-by-step deposition and in-situ PNR measurements. A multilayer Mo/[CoFeB/Mo]12 structure was grown, and neutron reflectivity curves measured after each cycle revealed the gradual evolution of sample properties. A weak magnetic field response suggested the potential formation of perpendicular magnetic anisotropy (PMA) at CoFeB/Mo interfaces. Additionally, a single CoFeB film was annealed up to 450{\deg}C, followed by the deposition of a ~5 Å Mo layer. PNR measurements in magnetic fields of 0.01 T and 0.75 T showed a significant increase in in-plane magnetization, confirming PMA formation. Thus, we demonstrate the first successful operation of a combined PLD and in-situ PNR system, showcasing its capabilities for characterizing single-layer CoFeB and multilayer CoFeB/Mo thin-film structures.

   ↳ physics.ins-detcond-mat.mes-hallcond-mat.mtrl-scinucl-exVacuum(2025)·0 citations
6. 06*

   Origin of perpendicular magnetic anisotropy in ultra-thin metal films studied by in-situ neutron reflectometry

   Grigorii Kirichuk🇷🇺 · Alexey Grunin🇷🇺 · Artur Dolgoborodov🇬🇪 · Pavel Prokopovich🇷🇺 · Petr Shvets🇷🇺 · Alexey Vorobiev🇸🇪 · Anton Devishvilli🇫🇷 · Alexandr Goikhman🇬🇪 · Ksenia Maksimova🇬🇪

   Perpendicular magnetic anisotropy (PMA) plays an important role in different spintronic devices. The rapid development of spintronics requires a better understanding of the nature and mechanisms of the PMA formation. In our article, we demonstrate the potential of studying PMA by in-situ polarized neutron reflectometry combined with pulsed laser deposition. Using these techniques, we show the formation of out-of-plane anisotropy in thin CoFeB films (1.8 nm) with a capping Mo layer. Investigating thick (5.3 nm}) and thin (0.5 nm) molybdenum films, we demonstrate that in both cases, PMA was established in bilayer structures without any thermal annealing. Also, we demonstrate how an additional silicon layer grown over the CoFeB/Mo bilayer can critically alter the magnetic properties of the sample. Such studies are possible only through the unique combination of the growth method with the in-situ polarized neutron reflectometry measurement technique. We believe that this approach will open up broad opportunities for the development and investigation of new spintronic devices.

   ↳ cond-mat.mes-hallcond-mat.mtrl-scicond-mat.othernucl-ex0 citations
7. 07*

   Energy dependence of transverse momentum fluctuations in Au+Au collisions from a multiphase transport model

   Liuyao Zhang🇨🇳 · Jinhui Chen🇨🇳 · Chunjian Zhang🇨🇳

   Event-by-event mean transverse momentum fluctuations ($⟨p_{\mathrm{T}}⟩$) serve as a sensitive probe of initial state overlap geometry and energy density fluctuations in relativistic heavy-ion collisions. We present a systematic investigation of $⟨p_{\mathrm{T}}⟩$ fluctuations in \auau collisions at $\sqrt{{\mathrm{s}}_{\mathrm{NN}}}=$3.0-19.6 GeV, examining their centrality and energy dependence with the framework of an improved multiphase transport (AMPT) model. The centrality dependence of the $p_{\mathrm{T}}$ cumulants up to fourth order deviates significantly from simple powering-law scaling. Scaled cumulants are performed, with variances aligning well with the trends observed in the experimental data. Employing a two-subevent method, short-range correlations are slightly suppressed compared to the standard approach. Furthermore, baryons exhibit more pronounced $⟨p_{\mathrm{T}}⟩$ fluctuations than mesons, potentially attributable to the effect of radial flow. These results provide referenced insights into the role of initial state fluctuations across different energies in heavy-ion collisions.

   ↳ nucl-thnucl-exPRC(2025)·15 citations
8. 08*

   Two- versus three-body approach to femtoscopic hadron-deuteron correlations

   Stanislaw Mrowczynski🇵🇱

   The three-body approach to hadron-deuteron correlations is shown to turn into a two-body approach if the three-particle hadron-deuteron wave function factorizes into the deuteron wave-function and the wave function of a hadron motion relative to the deuteron. Then, the hadron-deuteron correlation function is as in the two-body approach only the source radius somewhat changes. For this reason, as we argue, the two-body approach works well for kaon-deuteron correlations but it fails for proton-deuteron ones in case of small sources. Applying the three-body approach generalized to the case where the radius of the hadron source is different from the nucleon source radius, we derive the source radius formula which used in the two-body approach gives the correlation function as in the `factorized' three-body one. The formula is discussed in the context of existing and future experimental data.

   ↳ nucl-thhep-phnucl-exPLB(2025)·6 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.