Thu·Feb 9, 2023Thursday·February 9, 2023

1. 01*

   Measurements of the suppression and correlations of dijets in Xe+Xe collisions at $\sqrt{s_{NN}}$ = 5.44 TeV

   ATLAS Collaboration

   Measurements of the suppression and correlations of dijets is performed using 3 $\mu$b${}^{-1}$ of Xe+Xe data at $\sqrt{s_{\mathrm{NN}}}=5.44$ TeV collected with the ATLAS detector at the LHC. Dijets with jets reconstructed using the $R=0.4$ anti-$k_t$ algorithm are measured differentially in jet $p_{\text{T}}$ over the range of 32 GeV to 398 GeV and the centrality of the collisions. Significant dijet momentum imbalance is found in the most central Xe+Xe collisions, which decreases in more peripheral collisions. Results from the measurement of per-pair normalized and absolutely normalized dijet $p_{\text{T}}$ balance are compared with previous Pb+Pb measurements at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV. The differences between the dijet suppression in Xe+Xe and Pb+Pb are further quantified by the ratio of pair nuclear-modification factors. The results are found to be consistent with those measured in Pb+Pb data when compared in classes of the same event activity and when taking into account the difference between the center-of-mass energies of the initial parton scattering process in Xe+Xe and Pb+Pb collisions. These results should provide input for a better understanding of the role of energy density, system size, path length, and fluctuations in the parton energy loss.

   nucl-exhep-exPRC(2023)·8 citations
2. 02*

   Direct triple-$\alpha$ process in non-adiabatic approach

   M. Katsuma

   Triple-$\alpha$ reaction rates have been determined well with the sequential process via the narrow resonances. However, the direct triple-$\alpha$ process at off-resonant energies still remains in unsolved problems. In the present report, the direct triple-$\alpha$ contribution is estimated with a non-adiabatic method, and it is found to be 10${}^{-15}$--10${}^{-3}$ pb order in photodisintegration cross sections of ${}^{12}$C(2${}_1^{+}\to$ 0${}^{+}$) for $0.15<E<0.35$ MeV. This is far below the values predicted by the recent adiabatic models. In spite of the large difference, the derived rates are found to be concordant with NACRE at the helium burning temperatures.

   ↳ nucl-thastro-ph.SRnucl-ex1 citation
3. 03*

   Thermodynamic and hydrodynamic characteristics of interacting system formed in relativistic heavy ion collisions

   Xu-Hong Zhang🇨🇳 · Hao-Ning Wang🇨🇳 · Fu-Hu Liu🇨🇳 · Khusniddin K. Olimov🇺🇿

   To study the energy-dependent characteristics of thermodynamic and hydrodynamic parameters, based on the framework of a multi-source thermal model, we analyze the soft transverse momentum ($p_T$) spectra of the charged particles (${\pi }^{-}$, ${\pi }^{+}$, $K^{-}$, $K^{+}$, $\bar{p}$, and $p$) produced in gold-gold (Au-Au) collisions at the center-of-mass energies $\sqrt{s_{NN}}=7.7$, 11.5, 14.5, 19.6, 27, 39, 62.4, and 200 GeV from the STAR Collaboration and in lead-lead (Pb-Pb) collisions at $\sqrt{s_{NN}}=2.76$ and 5.02 TeV from the ALICE Collaboration. In the rest framework of emission source, the probability density function obeyed by meson momenta satisfies the Bose-Einstein distribution, and that obeyed by baryon momenta satisfies the Fermi-Dirac distribution. To simulate the $p_T$ of the charged particles, the kinetic freeze-out temperature $T$ and transverse expansion velocity ${\beta }_T$ of emission source are introduced into the relativistic ideal gas model. Our results, based on the Monte Carlo method for numerical calculation, show a good agreement with the experimental data. The excitation functions of thermodynamic parameter $T$ and hydrodynamic parameter ${\beta }_T$ are then obtained from the analyses, which shows an increase tendency from 7.7 GeV to 5.02 TeV in collisions with different centralities.

   ↳ hep-phhep-exnucl-exnucl-thIJMPE(2023)·1 citation
4. 04*

   The earliest DT nuclear fusion discoveries

   M. B. Chadwick🇺🇸 · G. M. Hale🇺🇸 · M. W. Paris🇺🇸 · J. P. Lestone · C. Bates · J. B. Wilhelmy · S. A. Andrews · W. Tornow🇺🇸 · S. W. Finch🇺🇸

   We describe the earliest measurements of the DT fusion cross section commissioned by the Manhattan Project, first at Purdue University in 1943 and then at Los Alamos 1945-6 and later, in 1951-2. The Los Alamos measurements led to the realization that a 3/2${}^{+}$ resonance in the DT system enhances the fusion cross section by a factor of one hundred at energies relevant to applications. This was a transformational discovery, making the quest for terrestrial fusion energy possible. The earliest measurements were reasonably accurate given the technology of the time and the scarcity of tritium, and were quickly improved to provide cross section data accurate to just a few percent. We provide a previously-unappreciated insight: that DT fusion was first reported in Ruhlig's 1938 University of Michigan experiment and likely influenced Konopinski in 1942 to suggest its usefulness for thermonuclear technologies. We report on preliminary work to repeat the 1938 measurement, and our simulations of that experiment. We also present some work by Fermi, from his 1945 Los Alamos lectures, showing that he used the S-factor concept about a decade before it was introduced by nuclear astrophysicists.

   ↳ physics.hist-phastro-ph.SRnucl-ex3 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.