Wed·Sep 13, 2023Wednesday·September 13, 2023

1. 01*

   Measurement of Two-Point Energy Correlators Within Jets in $pp$ Collisions at $\sqrt{s}$ = 200 GeV at STAR

   Andrew Tamis🇺🇸

   Jet substructure is a powerful tool to probe the time evolution of a parton shower. However, many of the analysis methods used to extract splitting formation times from jet substructure, such as Soft Drop grooming and the Lund plane, focus on the hardest radiation of the jet. A complementary observable with growing theoretical and experimental interest, the 2-point Energy Correlator (EEC), re-contextualizes jet substructure study by using the distribution of angular distance of all combinations of two final state particles within a jet. This distribution is weighted by the product of the fractions of jet energy that each of the constituents carry, and thus is infrared-and-collinear safe. The EEC can reveal the separation between two distinct regimes: effects originating from free hadrons at small opening angles and from perturbative fragmentation of quarks and gluons at large opening angles. In these proceedings, the first measurement of the EEC at RHIC is presented, using the data taken at $\sqrt{s}$ = 200 GeV $pp$ collisions by STAR. The EEC will be shown for several full jet transverse momentum selections and compared to predictions from the PYTHIA-8 Detroit tune. This study is useful as a baseline for comparisons to future studies in heavy-ion collisions, which will provide information about how the quark-gluon plasma interacts with the jet across different angular scales.

   ↳ hep-exnucl-exPoS(2024)·45 citations
2. 02*

   Extracting Kinetic Freeze-out Properties in High Energy Collisions Using a Multi-source Thermal Model

   Jia-Yu Chen🇨🇳 · Mai-Ying Duan🇨🇳 · Fu-Hu Liu🇨🇳 · Khusniddin K. Olimov🇺🇿

   We study the transverse momentum ($p_T$) spectra of neutral pions and identified charged hadrons produced in proton--proton ($pp$), deuteron--gold ($d$--Au), and gold--gold (Au--Au) collisions at the center of mass energy $\sqrt{s_{NN}}=200$ GeV. The study is made in the framework of a multi-source thermal model used in the partonic level. It is assumed that the contribution to the $p_T$-value of any hadron comes from two or three partons with an isotropic distribution of the azimuthal angle. The contribution of each parton to the $p_T$-value of a given hadron is assumed to obey any one of the standard (Maxwell-Boltzmann, Fermi-Dirac, and Bose-Einstein) distributions with the kinetic freeze-out temperature and average transverse flow velocity. The $p_T$-spectra of the final-state hadrons can be fitted by the superposition of two or three components. The results obtained from our Monte Carlo method are used to fit the experimental results of the PHENIX and STAR Collaborations. The results of present work serve as a suitable reference baseline for other experiments and simulation studies.

   ↳ hep-phhep-exnucl-exnucl-thAdv.High Energy Phys.(2024)·3 citations
3. 03*

   155Tb production by cyclotrons: what level of 155Gd enrichment allows clinical applications?

   Francesca Barbaro🇮🇹 · Luciano Canton🇮🇹 · Nikolay Uzunov · Laura De Nardo · Laura Melendez-Alafort

   BACKGROUND: 155Tb represents a potentially useful radionuclide for diagnostic medical applications, but its production remains a challenging problem. A recent experimental campaign, conducted with low-energy proton beams impinging on a 155Gd target with 91.9% enrichment, demonstrated a significant co-production of 156gTb, a contaminant of great concern since its half-life is comparable to that of 155Tb and its high-energy gamma emissions severely impact on the dose released and on the quality of the SPECT images. Herein, the isotopic purity of the enriched 155Gd target necessary to minimize the co-production of contaminant radioisotopes, in particular 156gTb, was explored using various computational simulations. RESULTS: Starting from the recent data obtained with the 155Gd-enriched target, the co-production of other Tb radioisotopes besides 155Tb has been evaluated using the TALYS code. It was found that 156Gd, with an isotopic content of 5.87%, was the principal contributor to the co-production of 156gTb. The analysis also demonstrated that the maximum amount of 156Gd admissible for 155Tb production with a radionuclidic purity higher than 99% was 1%. A less stringent condition was obtained through computational dosimetry analysis, suggesting that a 2% content of 156Gd in the target can be tolerated to limit the dose increase to the patient below the 10% limit. Moreover, it has been demonstrated that the imaging properties of the produced 155Tb are not severely affected by this level of impurity in the target. CONCLUSIONS: 155Tb can be produced with a quality suitable for medical applications using low-energy proton beams and 155Gd-enriched targets if the 156Gd impurity content does not exceed 2%. Under these conditions, the dose increase due to the presence of contaminant radioisotopes remains below the 10% limit and good quality images, comparable to those of 111In, are guaranteed.

   ↳ physics.med-phnucl-exnucl-thEJNMMI Physics(2024)·2 citations
4. 04*

   Nuclear ground-state properties probed by the relativistic Hartree-Bogoliubov approach

   Zi Xin Liu🇨🇳 · Yi Hua Lam🇫🇷 · Ning Lu · Peter Ring🇩🇪

   Using the relativistic Hartree-Bogoliubov framework with separable pairing force coupled with the latest covariant density functionals, i.e., PC-L3R, PC-X, DD-PCX, and DD-MEX, we systematically explore the ground-state properties of all isotopes of Z=8-110. These properties consist of the binding energies, one- and two-neutron separation energies ($S_{\mathrm{n}}$ and $S_{2n}$), root-mean-square radius of matter, of neutron, of proton, and of charge distributions, Fermi surfaces, ground-state spins and parities. We then predict the edges of nuclear landscape and bound nuclei for the isotopic chains from oxygen (Z=8) to darmstadtium (Z=110) based on these latest covariant density functionals. The number of bound nuclei predicted by PC-L3R, PC-X, DD-PCX, and DD-MEX, are 9004, 9162, 6799, and 7112, respectively. The root-mean-square deviations of $S_{\mathrm{n}}$ ($S_{2n}$) yielded from PC-L3R, PCX, DD-PCX, and DD-MEX are 0.962 (1.300) MeV, 0.920 (1.483) MeV, 0.993 (1.753) MeV, and 1.010 (1.544) MeV, respectively. The root-mean-square deviations of charge radius distributions of comparing the available experimental values with the theoretical counterparts resulted from PC-L3R, PC-X, DD-PCX, and DD-MEX are 0.035 fm, 0.037 fm, 0.035 fm, and 0.034 fm, respectively. We notice pronounced differences between the empirical and theoretical root-mean-square radii of neutron at nuclei near the neutron drip line of the Mg, Ca, and Kr isotopic chains, suggesting the possible existence of the halo or giant halo phenomena.

   ↳ nucl-thnucl-exAtom.Data Nucl.Data Tabl.(2024)·11 citations
5. 05*

   The trigger system for the CSR external-target experiment

   Dong Guo · Haoqian Xyu · DongDong Qi · HeXiang Wang · Lei Zhang · Zhengyang Sun · Zhi Qin · Botan Wang · Yingjie Zhou · Zekun Wang · Yuansheng Yang · Yuhao Qin and 5 other authors

   A trigger system has been designed and implemented for the HIRFL-CSR external target experiment (CEE), the spectrometer for studying nuclear matter properties with heavy ion collisions in the GeV energy region. The system adopts master-slave structure and serial data transmission mode using optical fiber to deal with different types of detectors and long-distance signal transmission. The trigger logic can be accessed based on command register and controlled by a remote computer. The overall field programmable gate array (FPGA) logic can be flexibly reconfigured online to match the physical requirements of the experiment. The trigger system has been tested in beam experiment. It is demonstrated that the trigger system functions correctly and meets the physical requirements of CEE.

   ↳ physics.ins-detnucl-exJINST(2024)·5 citations
6. 06*

   Early time dynamics far from equilibrium via holography

   Matthias Kaminski🇺🇸 · Casey Cartwright🇺🇸 · Marco Knipfer🇺🇸 · Michael F. Wondrak🇳🇱 · Björn Schenke🇺🇸 · Marcus Bleicher🇩🇪

   We investigate the early time dynamics of heavy ion collisions studying the time evolution of the energy-momentum tensor as well as energy-momentum correlations within a uniformly thermalizing holographic QGP. From these quantities, we suggest a far-from equilibrium definition of shear viscosity, which is a crucial property of QCD matter as it significantly determines the generation of elliptic flow already at early times. During an exemplary initial heating phase of the holographic QGP the shear viscosity of entropy density ratio decreases down to 60%, followed by an overshoot to 110% of the near-equilibrium value, $\eta /s=1/(4\pi )$. Implications for the QCD QGP are discussed. Subsequently, we consider a holographic QGP which is Bjorken-expanding. Its energy-momentum tensor components have a known hydrodynamic attractor to which all time evolutions collapse independent of the initial conditions. Based on this, we propose a definition for a far from equilibrium speed of sound, and analytically compute its hydrodynamic attractor. Subjecting this Bjorken-expanding plasma to an external magnetic field and an axial chemical potential, we study the chiral magnetic effect far from equilibrium.

   ↳ nucl-thhep-lathep-phhep-th+1PoS(2024)·1 citation
7. 07*

   Correlations of Baryon and Charge Stopping in Heavy Ion Collisions

   Wendi Lv🇨🇳 · Yang Li🇨🇳 · Ziyang Li🇨🇳 · Rongrong Ma🇺🇸 · Zebo Tang🇨🇳 · Prithwish Tribedy🇺🇸 · Chun Yuen Tsang🇺🇸 · Zhangbu Xu🇺🇸 · Wangmei Zha🇨🇳

   Baryon numbers are carried by valence quarks in the standard QCD picture of the baryon structure, while some theory proposed an alternative baryon number carrier, a non-perturbative Y-shaped configuration of the gluon field, called the baryon junction in the 1970s. However, neither of the theories has been verified experimentally. It was recently suggested to search for the baryon junction by investigating the correlation of net-charge and net-baryon yields at midrapidity in heavy-ion collisions. This paper presents studies of such correlations in collisions of various heavy ions from Oxygen to Uranium with the UrQMD Monte Carlo model. The UrQMD model implements valence quark transport as the primary means of charge and baryon stopping at midrapidity. Detailed study are also carried out for isobaric ${}_{40}^{96}\mathrm{Zr}$ + ${}_{40}^{96}\mathrm{Zr}$ and ${}_{44}^{96}\mathrm{Ru}$ + ${}_{44}^{96}\mathrm{Ru}$ collisions. We found a universal trend of the charge stopping with respect to the baryon stopping, and that the charge stopping is always more than the baryon stopping. This study provides a model baseline in valence quark transport for what is expected in net-charge and net-baryon yields at midrapidity of relativistic heavy-ion collisions.

   ↳ nucl-thnucl-exCPC(2024)·12 citations
8. 08*

   Feasibility studies for imaging e${}^{+}$e${}^{-}$ annihilation with modular multi-strip detectors

   S. Sharma🇵🇱 · L. Povolo · S. Mariazzi🇮🇹 · G. Korcyl🇵🇱 · K. Kacprzak🇵🇱 · D. Kumar🇩🇪 · S. Niedzwiecki🇵🇱 · J. Baran · E. Beyene · R.S. Brusa · R. Caravita🇮🇹 · N. Chug🇵🇱 and 32 other authors

   Studies based on imaging the annihilation of the electron (e${}^{-}$) and its antiparticle positron (e${}^{+}$) open up several interesting applications in nuclear medicine and fundamental research. The annihilation process involves both the direct conversion of e${}^{+}$e${}^{-}$ into photons and the formation of their atomically bound state, the positronium atom (Ps), which can be used as a probe for fundamental studies. With the ability to produce large quantities of Ps, manipulate them in long-lived Ps states, and image their annihilations after a free fall or after passing through atomic interferometers, this purely leptonic antimatter system can be used to perform inertial sensing studies in view of a direct test of Einstein equivalence principle. It is envisioned that modular multistrip detectors can be exploited as potential detection units for this kind of studies. In this work, we report the results of the first feasibility study performed on a e${}^{+}$ beamline using two detection modules to evaluate their reconstruction performance and spatial resolution for imaging e${}^{+}$e${}^{-}$ annihilations and thus their applicability for gravitational studies of Ps.

   ↳ physics.ins-detnucl-exNucl.Instrum.Meth.A(2024)·3 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.