Mon·Aug 7, 2023Monday·August 7, 2023

1. 01*

   Isomeric pair ${}^{95\mathrm{m},\mathrm{g}}\mathrm{Nb}$ in photonuclear reactions on ${}^{\mathrm{nat}}$Mo at end-point bremsstrahlung energy of 35-95 MeV

   I.S. Timchenko🇸🇰 · O.S. Deiev🇺🇦 · S.M. Olejnik🇺🇦 · S.M. Potin🇺🇦 · V.A. Kushnir🇺🇦 · V.V. Mytrochenko🇺🇦 · S.A. Perezhogin🇺🇦 · V.A. Bocharov🇺🇦

   The ${}^{\mathrm{nat}}\mathrm{Mo}(\gamma ,x\mathrm{np}{)}^{95\mathrm{m},\mathrm{g}}$Nb photonuclear reaction was studied using the electron beam from the NSC KIPT linear accelerator LUE-40. Experiment was performed using the activation and off-line $\gamma$-ray spectrometric technique. The experimental isomeric yield ratio $d(E_{\gamma \max })=Y_{\mathrm{m}}(E_{\gamma \max })/Y_{\mathrm{g}}(E_{\gamma \max })$ was determined for the reaction products ${}^{95\mathrm{m},\mathrm{g}}\mathrm{Nb}$ at the end-point bremsstrahlung energy $E_{\gamma \max }$ range of 35-95 MeV. The obtained values of $d(E_{\gamma \max })$ are in satisfactory agreement with the results of other authors and extend the range of previously known data. The theoretical values of the yields $Y_{\mathrm{m},\mathrm{g}}(E_{\gamma \max })$ and the isomeric yield ratio $d(E_{\gamma \max })$ for the isomeric pair ${}^{95\mathrm{m},\mathrm{g}}\mathrm{Nb}$ from the ${}^{\mathrm{nat}}\mathrm{Mo}(\gamma ,x\mathrm{np})$ reaction were calculated using the partial cross-sections $\sigma (E)$ from the TALYS1.95 code for six different level density models $LD$. The comparison showed a noticeable excess (more than 3.85 times) of the experimental isomeric yield ratio over all theoretical estimates. At the investigated range of $E_{\gamma \max }$ the theoretical dependence of $d(E_{\gamma \max })$ on energy was confirmed - the isomeric yield ratio smoothly decreases with increasing energy.

   nucl-exCPC(2023)·6 citations
2. 02*

   Measurements of direct-photon production in Pb-Pb collisions at $\sqrt{{\mathrm{s}}_{\mathrm{NN}}}=5.02$ TeV and $\sqrt{{\mathrm{s}}_{\mathrm{NN}}}=2.76$ TeV with the ALICE experiment

   A. Marin (for the ALICE Collaboration)🇩🇪

   Recent results on direct-photon measurements in Pb-Pb collisions at \fivenn from central to peripheral collisions, as well as in 0-10% central and 20-40% semicentral Pb-Pb collisions at \sqrt{ s_{NN}}=2.76 TeV with improved significance are presented. A significant direct-photon signal is measured for p_T \gtrapprox 2 GeV/c from central to peripheral Pb-Pb collisions at \sqrt{s_{NN}}=5.02 TeV which is in agreement with model calculations containing pre-equilibrium photons in the intermediate p_T range and prompt photons at high p_T. No significant direct-photon signal is measured in the low p_T interval which is also in agreement with the small thermal-photon signal predicted by state-of-the art models. On the other hand, a direct-photon signal is measured for p_T > 1 GeV/c with a significance of 3.1 ($1.0<p_{\mathrm{T}}<1.8$ GeV/c) and 3.4 (1.0 < p_T < 2.3 GeV/c) in 0-10% and 20-40% central Pb-Pb collisions at \sqrt{s_{NN}}=2.76 TeV, respectively. The inverse slope parameters of non-prompt photon spectra in the low p_T range, 1.1 < p_T < 2.1 GeV/c, are T_ eff = 343 \pm 32 (stat)\pm 68(sys) MeV and T_eff = 339 \pm 32 (stat)\pm 68(sys) MeV for central and semicentral collisions. In the intermediate p_T} range, 2.1 < p_T < 4.0 GeV/c, the effective temperatures are T_{eff} = 406 \pm 19 (stat)\pm 36(sys) MeV and T_eff = 458 \pm 25 (stat)\pm 40(sys) MeV, respectively. The effective temperatures T_eff in the intermediate p_T range are systematically larger compared to those obtained at low p_T (although consistent within uncertainties) which may indicate an earlier photon emission, and thus sensitivity to pre-equilibrium photon production. Direct photons at both energies are in agreement with state-of-the-art theory calculations over the complete p_T range and measured centralities.

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

   Increasing the rate capability for the cryogenic stopping cell of the FRS Ion Catcher

   J.W. Zhao · D. Amanbayev · T. Dickel · I. Miskun · W. R. Plass · N. Tortorelli · S. Ayet San Andres · Soenke Beck · J. Bergmann · Z. Brencic · P. Constantin · H. Geissel and 36 other authors

   At the FRS Ion Catcher (FRS-IC), projectile and fission fragments are produced at relativistic energies, separated in-flight, energy-bunched, slowed down, and thermalized in the ultra-pure helium gas-filled cryogenic stopping cell (CSC). Thermalized nuclei are extracted from the CSC using a combination of DC and RF electric fields and gas flow. This CSC also serves as the prototype CSC for the Super-FRS, where exotic nuclei will be produced at unprecedented rates making it possible to go towards the extremes of the nuclear chart. Therefore, it is essential to efficiently extract thermalized exotic nuclei from the CSC under high beam rate conditions, in order to use the rare exotic nuclei which come as cocktail beams. The extraction efficiency dependence on the intensity of the impinging beam into the CSC was studied with a primary beam of 238U and its fragments. Tests were done with two different versions of the DC electrode structure inside the cryogenic chamber, the standard 1 m long and a short 0.5 m long DC electrode. In contrast to the rate capability of 10^4 ions/s with the long DC electrode, results show no extraction efficiency loss up to the rate of 2x10^5 ions/s with the new short DC electrode. This order of magnitude increase of the rate capability paves the way for new experiments at the FRS-IC, including exotic nuclei studies with in-cell multi-nucleon transfer reactions. The results further validate the design concept of the CSC for the Super-FRS, which was developed to effectively manage beams of even higher intensities.

   ↳ physics.ins-detnucl-exNucl.Instrum.Meth.B(2024)·3 citations
4. 04*

   First measurement of discrimination between helium and electron recoils in liquid xenon for low-mass dark matter searches

   S. J. Haselschwardt🇺🇸 · R. Gibbons🇺🇸 · H. Chen🇺🇸 · S. Kravitz🇺🇸 · A. Manalaysay🇺🇸 · Q. Xia🇺🇸 · P. Sorensen🇺🇸 · W. H. Lippincott🇺🇸

   We report the first measurement of discrimination between low-energy helium recoils and electron recoils in liquid xenon. This result is relevant to proposed low-mass dark matter searches which seek to dissolve light target nuclei in the active volume of liquid-xenon time projection chambers. Low-energy helium recoils were produced by degrading $\alpha$ particles from ${}^{210}$Po with a gold foil situated on the cathode of a liquid xenon time-projection chamber. The resulting population of helium recoil events is well separated from electron recoils and is also offset from the expected position of xenon nuclear recoil events.

   ↳ hep-exnucl-exPRL(2024)·8 citations
5. 05*

   Tandem-ABALONETM Photosensors with $2\times 2\pi$ Acceptance for Neutrino Astronomy

   Ivan Ferenc Šegedin🇺🇸 · Marija Šegedin Ferenc🇺🇸 · Daniel Ferenc🇺🇸

   The primary goal of the novel photosensor technology called ABALONETM (U.S. Pat. 9,064,678) has been to enable the next-generation of astroparticle physics experiments to open new windows on the universe with large-area detectors of unprecedented performance, radio-purity, robustness, and integration flexibility. This foundational technology provides the means for modern, scalable and cost-effective production. The wide range of possible application-specific detector configurations can also make a difference in homeland security and medical imaging. Thus far, we have reduced to practice two such detector configurations: (i) the composite sandwich Panel assembly that hosts matrices of closely packed ABALONE units (U.S. Pat. 10,823,861), and, quite differently, the Tandem Detector Modules that host two back-to-back oriented ABALONE photosensors. This article for the first time presents the latter configuration, specifically designed to provide $2\times 2\pi$ angular acceptance for neutrino astronomy and other large-area radiation detectors.

   ↳ physics.ins-detastro-ph.IMhep-exnucl-exNucl.Instrum.Meth.A(2024)·0 citations
6. 06*

   Decay of ${}^{99m}$Tc as part of calibration procedure for ${}^{192}$Ir activity measurements using a well type ionization chamber

   Marco A. Ridenti · Paulo R. Pascholati · Suzana Botelho · Josemary A. C. Gonçalves · Carmen C. Bueno

   In this work the linearity in the response of an ionization-chamber as a function of ${}^{99m}$Tc activity was checked as part of a calibration procedure for ${}^{192}$Ir activity measurements. The non-linearity was found to be caused mainly by the electrometer range switching. A model based on the hypothesis that the non-linear effect did not influence the decay constant was tested. This method allowed to correct the non-linear effect and obtain the 99mTc activity with good acuracy.

   ↳ physics.ins-detnucl-exIn: XXX RTFNB Proceedings, \'Aguas de Lin…·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.