Thu·Aug 22, 2024Thursday·August 22, 2024

1. 01*

   Observation of Thermal Deuteron-Deuteron Fusion in Ion Tracks

   K. Czerski · R. Dubey🇿🇦 · A. Kowalska · G. Haridas Das · M. Kaczmarski · N. Targosz-Sleczka · M. Valat

   A direct observation of the deuteron-deuteron (DD) fusion reaction at thermal meV energies, although theoretically possible, is not succeeded up to now. The electron screening effect that reduces the repulsive Coulomb barrier between reacting nuclei in metallic environments by several hundreds of eV and is additionally increased by crystal lattice defects in the hosting material, leads to strongly enhanced cross sections which means that this effect might be studied in laboratories. Here we present results of the 2H(d,p)3H reaction measurements performed on a ZrD2 target down to the lowest deuteron energy in the center mass system of 675 eV, using an ultra-high vacuum accelerator system, recently upgraded to achieve high beam currents at very low energies. The experimental thick target yield, decreasing over seven orders of magnitude for lowering beam energies, could be well described by the electron screening energy of 340 eV, which is much higher than the value of about 100 eV for a defect free material. At the energies below 2.5 keV, a constant plateau yield value could be observed. As indicated by significantly increased energies of emitted protons, this effect can be associated with the thermal DD fusion. A theoretical model explains the experimental observations by creation of ion tracks induced in the target by projectiles, and a high phonon density which locally increases temperature above the melting point. The nuclear reaction rate taking into account recently observed DD threshold resonance agrees very well with the experimental data.

   nucl-ex4 citations
2. 02*

   Measurement of inclusive jet cross section and substructure in $p$$+$$p$ collisions at $\sqrt{s_{{}_{NN}}}=200$ GeV

   PHENIX Collaboration: N.J. Abdulameer🇭🇺 · U. Acharya🇺🇸 · C. Aidala🇺🇸 · N.N. Ajitanand🇺🇸 · Y. Akiba🇯🇵 · R. Akimoto🇯🇵 · J. Alexander🇺🇸 · M. Alfred🇺🇸 · V. Andrieux🇺🇸 · S. Antsupov🇷🇺 · K. Aoki🇯🇵 · N. Apadula🇺🇸 and 435 other authors

   The jet cross-section and jet-substructure observables in $p$$+$$p$ collisions at $\sqrt{s}=200$ GeV were measured by the PHENIX Collaboration at the Relativistic Heavy Ion Collider (RHIC). Jets are reconstructed from charged-particle tracks and electromagnetic-calorimeter clusters using the anti-$k_t$ algorithm with a jet radius $R=0.3$ for jets with transverse momentum within $8.0<p_T<40.0$ GeV/$c$ and pseudorapidity $|\eta |<0.15$. Measurements include the jet cross section, as well as distributions of SoftDrop-groomed momentum fraction ($z_g$), charged-particle transverse momentum with respect to jet axis ($j_T$), and radial distributions of charged particles within jets ($r$). Also meaureed was the distribution of $\xi =-ln(z)$, where $z$ is the fraction of the jet momentum carried by the charged particle. The measurements are compared to theoretical next-to and next-to-next-to-leading-order calculatios, PYTHIA event generator, and to other existing experimental results. Indicated from these meaurements is a lower particle multiplicity in jets at RHIC energies when compared to models. Also noted are implications for future jet measurements with sPHENIX at RHIC as well as at the future Electron-Ion Collider.

   ↳ hep-exnucl-exPRD(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.