Tue·Nov 14, 2023Tuesday·November 14, 2023

1. 01*

   Revisit to the yield ratio of triton and ${}^3$He as an indicator of neutron-rich neck emission

   Yijie Wang · Mengting Wan · Xinyue Diao · Sheng Xiao · Yuhao Qin · Zhi Qin · Dong Guo · Dawei Si · Boyuan Zhang · Baiting Tian · Fenhai Guan · Qianghua Wu and 25 other authors

   The neutron rich neck zone created in heavy ion reaction is experimentally probed by the production of the $A=3$ isobars. The energy spectra and angular distributions of triton and ${}^3$He are measured with the CSHINE detector in ${}^{86}$Kr +${}^{208}$Pb reactions at 25 MeV/u. While the energy spectrum of ${}^3$He is harder than that of triton, known as "${}^3$He-puzzle", the yield ratio $R(\mathrm{t}{/}^3\mathrm{He})$ presents a robust rising trend with the polar angle in laboratory. Using the fission fragments to reconstruct the fission plane, the enhancement of out-plane $R(\mathrm{t}{/}^3\mathrm{He})$ is confirmed in comparison to the in-plane ratios. Transport model simulations reproduce qualitatively the experimental trends, but the quantitative agreement is not achieved. The results demonstrate that a neutron rich neck zone is formed in the reactions. Further studies are called for to understand the clustering and the isospin dynamics related to neck formation.

   nucl-exnucl-thNucl.Sci.Tech.(2025)·6 citations
2. 02*

   Dilepton production at next-to-leading order and intermediate invariant-mass observables

   Jessica Churchill🇨🇦 · Lipei Du🇨🇦 · Charles Gale🇨🇦 · Greg Jackson🇫🇷 · Sangyong Jeon🇨🇦

   The thermal QCD dilepton production rate is calculated at next-to-leading order in the strong coupling and at finite baryon chemical potential. The two-loop virtual photon self-energy is evaluated using finite temperature field theory and combined consistently with the self-energy in the Landau-Pomeranchuk-Migdal regime. We present new results for a dense baryonic plasma. The rates are then integrated using (3+1)-dimensional fluid-dynamical simulations calibrated to reproduce hadronic experimental results obtained at RHIC at energies ranging from those of the Beam Energy Scan to $\sqrt{s_{{}_{\mathrm{NN}}}}=200$ GeV. We elaborate on the ability for dileptons to relay information about the plasma baryonic content and temperature.

   ↳ nucl-thhep-exhep-phnucl-exPRC(2024)·40 citations
3. 03*

   Virtual Photons Shed Light on the Early Temperature of Dense QCD Matter

   Jessica Churchill🇨🇦 · Lipei Du🇨🇦 · Charles Gale🇨🇦 · Greg Jackson🇺🇸 · Sangyong Jeon🇨🇦

   Dileptons produced during heavy-ion collisions represent a unique probe of the QCD phase diagram, and convey information about the state of the strongly interacting system at the moment their preceding off-shell photon is created. In this study, we compute thermal dilepton yields from Au+Au collisions performed at different beam energies, employing a (3+1)-dimensional dynamic framework combined with emission rates accurate at next-to-leading order in perturbation theory and which include baryon chemical potential dependencies. By comparing the effective temperature extracted from the thermal dilepton invariant mass spectrum with the average temperature of the fluid, we offer a robust quantitative validation of dileptons as effective probe of the early quark-gluon plasma stage.

   ↳ nucl-thhep-exhep-phnucl-exPRL(2024)·38 citations
4. 04*

   Particle Identification at VAMOS++ with Machine Learning Techniques

   Y. Cho · Y. H. Kim · S. Choi · J. Park · S. Bae · K. I. Hahn · Y. Son · A. Navin · A. Lemasson · M. Rejmund · D. Ramos · D. Ackermann and 36 other authors

   Multi-nucleon transfer reaction between 136Xe beam and 198Pt target was performed using the VAMOS++ spectrometer at GANIL to study the structure of n-rich nuclei around N=126. Unambiguous charge state identification was obtained by combining two supervised machine learning methods, deep neural network (DNN) and positional correction using a gradient-boosting decision tree (GBDT). The new method reduced the complexity of the kinetic energy calibration and outperformed the conventional method, improving the charge state resolution by 8%

   ↳ physics.ins-detnucl-exNuclear Instruments and Methods in Physic…
5. 05*

   Optimal colliding energy for the synthesis of superheavy element $Z$=119

   Avazbek Nasirov (1 and 2) · Bakhodir Kayumov (3 and 2) ((1) Joint Institute for Nuclear Research, Dubna, Russia, (2) Institute of Nuclear Physics, Tashkent, Uzbekistan, (3) School of Humanities and Natural Sciences, New Uzbekistan University, Tashkent, Uzbekistan)

   The evaporation residue (ER) cross section of 3n and 4n channels related to the synthesis of superheavy element (SHE) with the charge number $Z=119$ in the ${}^{51}$V+${}^{248}$Cm reaction has been calculated by the dinuclear system (DNS) model as a sum of the partial cross sections of the corresponding channels. The angular momentum distribution of the compound nucleus is estimated by the dynamical trajectory calculations of the capture probability which is considered as the DNS formation probability. The fusion probability decreases by the increase of the DNS angular momentum due to its influence on the intrinsic fusion barrier $B_{\mathrm{fus}}^{\ast }$. The range ${\alpha }_2=60^{\circ }÷70^{\circ }$ of the orientation angle of the axial symmetry axis of the deformed target nucleus ${}^{248}$Cm is favorable for the formation of the compound nucleus. The fusion probability decreases at around ${\alpha }_2=90^{\circ }$ since the number of the partial waves contributing to the capture decreases. Therefore, it is important to calculate the capture cross section dynamically. The 4n channel cross section of the SHE synthesis is larger than the 3n channel cross section maximum value of the ER cross section is 12.3 fb at $E_{c.m.}$=232 MeV.

   ↳ nucl-thnucl-exPRC(2024)·17 citations
6. 06*

   Quantal effect on the opening angle distribution between the fission fragment's spins

   Guillaume Scamps🇺🇸

   Background: Several approaches are currently trying to understand the generation of angular momentum in the fission fragments. The microscopic TDDFT and statistical FREYA lead to different predictions concerning the opening angle distribution formed between the two spins in particular at 0 and 180 degrees. Purpose: This letter aims to investigate how the geometry and the quantum nature of spins impact the distribution of opening angles to understand what leads to different model predictions. Method: Various assumptions of K distribution (K=0, isotropic, isotropic with total K=0, and from TDFFT) are investigated in a quantum approach. These distributions are then compared to the classical limit using the Clebsch-Gordan coefficients in the limit of $\hslash$ approaches zero. Results: It is shown that in all the schematic scenario the quantal distribution of opening angle lead to the expected behavior in the classical limit. The model shows that the quantal nature of the spins prevents the population of opening angles close to 0 and 180 degrees. The difference in opening angle in the 2D and isotropic 3D distribution is discussed and it is shown that the realistic TDFFT opening angle distribution presents an intermediate behavior between the two cases. Conclusions: The last comparison reveals two key differences between the two models' predictions: the quantal spins' nature in TDDFT and the assumption of zero K values in FREYA.

   ↳ nucl-thnucl-exquant-phPRC(2024)·12 citations
7. 07*

   Performance of new Kuraray wavelength-shifting fibers with short decay time

   Shoma Kodama🇯🇵 · Hokuto Kobayashi · Wataru Okinaga · Kota Nakagiri🇯🇵 · Yasuhiro Nakajima🇯🇵 · Masashi Yokoyama🇯🇵

   We measure the decay time and the attenuation length of newly developed wavelength-shifting fibers, YS series from Kuraray, which have fast response. Using a 405 nm laser, the decay times of the YS-2, 4, and 6 are measured to be $3.64\pm 0.04$ ns, $2.15\pm 0.03$ ns, and $1.47\pm 0.02$ ns, respectively, for the light injection distance of 10 cm. The decay time of Y-11 is measured to be $7.10\pm 0.09$ ns using the same system. All fibers are found to have similar attenuation lengths of more than 4 meters. When combined with the plastic scintillators EJ-200 and EJ-204, the YS series have better time resolution than Y-11, with light yields of 60-100% of Y-11.

   ↳ physics.ins-dethep-exnucl-exPTEP(2024)·5 citations
8. 08*

   Isolating perturbative QCD splittings in heavy-ion collisions

   Leticia Cunqueiro🇮🇹 · Daniel Pablos🇮🇹 · Alba Soto-Ontoso🇨🇭 · Martin Spousta🇨🇿 · Adam Takacs🇳🇴 · Marta Verweij🇳🇱

   We define a new strategy to scan jet substructure in heavy-ion collisions. The scope is multifold: (i) test the dominance of vacuum jet dynamics at early times, (ii) capture the transition from coherent to incoherent jet energy loss, and (iii) study elastic scatterings in the medium, which are either hard and perturbative or soft and responsible for jet thermalisation. To achieve that, we analyse the angular distribution of the hardest splitting, ${\theta }_{\mathrm{hard}}$, above a transverse momentum scale, $k_t^{\min }$, in high-$p_t$ jets. Sufficiently high values of $k_t^{\min }$ target the regime in which the observable is uniquely determined by vacuum-like splittings and energy loss, leaving the jet substructure unmodified compared to proton-proton collisions. Decreasing $k_t^{\min }$ enhances the sensitivity to the relation between energy loss and the intra-jet structure and, in particular, to observe signatures of colour decoherence at small angles. At wider angles it also becomes sensitive to hard elastic scatterings with the medium and, therefore, the perturbative regime of medium response. Choosing $k_t^{\min }\approx 0$ leads to order one effects of non-perturbative origin such as hadronisation and, potentially, soft scatterings responsible for jet thermalisation. We perform a comprehensive analysis of this observable with three state-of-the-art jet-quenching Monte Carlo event generators. Our study paves the way for defining jet observables in heavy-ion collisions dominated by perturbative QCD and thus calculable from first principles.

   ↳ hep-phhep-exnucl-exnucl-thPRD(2024)·28 citations
9. 09*

   Digital Transformation of High Voltage Isolation Control and Monitoring System for HVE-400 Ion Implanter

   Chengbo Li · Xuepeng Sun🇨🇳 · Zhiguo Liu · Chungang Guo🇨🇳 · Xiaoming Li🇨🇳

   HVE-400 ion implanter is special ion implantation equipment for semiconductor materials boron and phosphorus doping. The ion source and extraction deflection system are at high voltage platform, while the corresponding control system is at ground voltage position. The control signals and measurement signals of various parameters at the high-voltage end need to be transmitted between ground voltage and high voltage through optical fibers to isolate high voltage. Upgrading is carried out due to the aging of the optical fiber transmission control and monitoring system, which cannot work stably. The transformation replaces the original distributed single-point control method with an advanced distributed centralized control method, and integrates all control and monitoring functions into an industrial control computer for digital operation and display. In the computer software, two kinds of automatic calculation of ion mass number are designed. After upgrading, the implanter high-voltage platform control and monitoring system features digitalization, centralized control, high reliability, strong anti-interference, fast communication speed, and easy operation.

   ↳ physics.ins-detnucl-exEPJ Tech.Instrum.(2024)·0 citations
10. 10*

    CATLIFE (Complementary Arm for Target LIke FragmEnts): Spectrometer for Target like fragments at VAMOS++

    Y. Son · Y.H. Kim · Y. Cho · S. Choi · S. Bae · K.I. Hahn · J. Park · A. Navin · A. Lemasson · M. Rejmund · D. Ramos · E. Clément and 7 other authors

    The multi-nucleon transfer reaction between 136Xe beam and 198Pt target at the beam energy 7 MeV/u was studied using the large acceptance spectrometer VAMOS++ coupled with the newly installed second arm time-of-flight and delayed $\gamma$-ray spectrometer CATLIFE (Complementary Arm for Target LIke FragmEnts). The CATLIFE detector is composed of a large area multi-wire proportional chamber and the EXOGAM HPGe clover detectors with an ion flight length of 1230 mm. Direct measurement of the target-like fragments (TLF) and the delayed $\gamma$-rays from the isomeric state helps to improve TLF identification. The use of the velocity of TLFs and the delayed $\gamma$-ray demonstrate the proof of principle and effectiveness of the new setup.

    ↳ physics.ins-detnucl-exNuclear Instruments and Methods in Physic…

* 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.