Bulletin of the American Physical Society
Fall 2022 Meeting of the APS Division of Nuclear Physics
Volume 67, Number 17
Thursday–Sunday, October 27–30, 2022; Time Zone: Central Daylight Time, USA; New Orleans, Louisiana
Session LC: Instrumentation IV |
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Chair: Patrizia Rossi, Jefferson Lab Room: Hyatt Regency Hotel Celestin A |
Saturday, October 29, 2022 2:00PM - 2:12PM |
LC.00001: Measurement of nuclear deformation in high-energy isobaric $^{96}$Ru+$^{96}$Ru and $^{96}$Zr+$^{96}$Zr collisions at STAR Chunjian Zhang The isobaric $^{96}$Ru+$^{96}$Ru and $^{96}$Zr+$^{96}$Zr collisions, arguably, the most unique colliding systems so far in high energy experiments, provide a valuable experimental test of nuclear structure. In this talk, we will present the precision measurements of bulk observables such as anisotropic flow $v_n$, non-linear mode coupling coefficients $\chi_n$, fluctuations of mean transverse momentum $c_{n,[p_T]}$, and Pearson correlation coefficients $\rho(v_n^2,[p_T])$ in $^{96}$Ru+$^{96}$Ru and $^{96}$Zr+$^{96}$Zr collisions at $\sqrt{s_{NN}}=$ 200 GeV. We will discuss how the significant deviations of the ratios of aforementioned observables in Ru+Ru collisions over Zr+Zr collisions from unity are indicative of large quadrupole and octuple deformations, and different neutron surface diffuseness in Ru and Zr nuclei, respectively. Furthermore, we will discuss how the comparison of such data with state-of-the-art hydrodynamic models infers the shape of the colliding nuclei and quantitatively constrains the nuclear structure parameters. |
Saturday, October 29, 2022 2:12PM - 2:24PM |
LC.00002: Improving Energy Resolution for the STAR Forward Calorimeter System David Kapukchyan The STAR experiment at the Relativistic Heavy Ion Collider, RHIC, has recently installed and operated an upgrade to its forward detector capabilities at 2.5<η<4.0 that consists of tracking (small thin gap chambers and silicon) and a forward calorimetry system (FCS) for RHIC Run 22 and beyond. The new detectors will be used to make novel measurements in cold QCD such as those related to the nucleon spin structure. This talk will focus on the FCS, which consists of a hodoscope preshower, a lead-scintillator electromagnetic calorimeter, and a steel-scintillator hadronic calorimeter. In addition, the FCS utilizes the latest electronics systems that allows for much greater energy resolution by recording fixed time snapshots of the readout signal, where several snapshots encompass a single collision. This allows the resulting data for a single event to contain the signals from multiple different collisions. This talk will discuss the algorithm being developed to distinguish the signals from each individual collision and how to disentangle the energy contribution from overlapping signals that arise either from multiple particles traversing the calorimeter in the same collision or signals from previous or post collision crossings that overlap with the triggered collision. |
Saturday, October 29, 2022 2:24PM - 2:36PM |
LC.00003: Calibrating the Electromagnetic Calorimeter of the STAR Forward Calorimeter System using p + p collision data at √s = 510 GeV data Xilin Liang The motivation for the STAR forward upgrade is to explore a wide range of rich cold QCD physics in the very high and low regions of Bjorken x. This requires new detector capabilities in the forward rapidities (2.5 < η < 4) including a new Electromagnetic Calorimeter (ECal) in the Forward Calorimeter System (FCS). The ECal was utilized for data taking during the 2022 RHIC run. However, radiation damage has been observed and varied for different ECal towers. Reconstruction of π0 is developed for calibrating the ECal, studying the gain correction factor for each ECal tower by iterating the π0 reconstruction. The analysis to study the radiation damage for the whole data period and the resulting gain correction factors from the π0 reconstruction using the p + p collision data at √s = 510 GeV for each ECal tower will be presented. |
Saturday, October 29, 2022 2:36PM - 2:48PM |
LC.00004: Optimization of the Cluster Finder of the STAR Forward Calorimeter System Manuel A Rosales The Forward Calorimeter System (FCS) is part of a newly installed upgrade to STAR experiment at RHIC (STAR) that is designed to expand measurements of quark and gluon spin dynamics in the proton at very high and low momentum fractions. The new sub-detectors consist of a sampling Electromagnetic Calorimeter (ECal) and a Hadronic Calorimeter (HCal) that will allow for full reconstruction of the energy and spatial distributions of electrons, hadrons and jets scattered at far forward pseudo-rapidities $(2.5 < \eta < 4)$. Reconstruction of charged hadrons requires the optimization of a cluster finder that allows for cluster matching between calorimeters and the reconstructed tracks at forward rapidities with the other two new sub-detectors, a Silicon-strip tracker and small-strip Thin Gap Chambers. This presentation will discuss the tuning of the cluster-finding algorithm in the HCal and the performance for single and multi-particle simulated events. |
Saturday, October 29, 2022 2:48PM - 3:00PM |
LC.00005: small-Strip Thin Gap Chamber as a STAR forward tracker Prashanth Shanmuganathan The STAR experiment at the Relativistic Heavy Ion Collider has undergone comprehensive detector upgrades in the forward region, providing precise identification of pions, photons, electrons, jets and as well as hadrons in the pseudorapidity region 2.5 to 4. In this contribution we focus on the small-Strip Thin Gap Chamber (sTGC), a variant of Multi-Wire Proportional Counters, which provides better spatial resolution at high particle flux regions. Four planes of sTGC detectors, each with four quadrants were installed. Each quadrant is a double sided chamber with diagonal stripes that give x, y, u in each plane, and provide position resolution < 200 μm. For the optimum operation the chambers require a n-Pentane and CO2 gas-mixture by volume 45%:55% at very low pressure and flow. A gas system with its associated safety system was built to fulfill the above requirement. The readout is based on ATLAS VMM chips developed for the ATLAS sTGC chambers. In this talk we will present instal- lation, commissioning and performance of the detector during the RHIC 2022 500 GeV p+p run.
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Saturday, October 29, 2022 3:00PM - 3:12PM |
LC.00006: Hadronic Calorimeter Cosmic Muon Calibrations Hanpu Jiang, Shuhang Li, William A Zajc, Emma McLaughlin, Blair D Seidlitz, Stefan Bathe, Daniel Richford The sPHENIX experiment has two layers of the Hadronic Calorimeter (HCal). The outer HCal is the outermost layer outside the solenoid coil, while the inner HCal is inside the magnet immediately outside the Electromagnetic Calorimeter. The sPHENIX program calls for precise measurements of jets to analyze the microscopic properties of the strongly interacting quark-gluon plasma and therefore requires a well-calibrated energy scale for the calorimeters. This talk will focus on the progress of the calibration for both the inner and outer HCal using cosmic muons. We record the energy deposited by muons passing through the sectors, and select events where the muons pass through all tiles in a tower. Our primary diagnostic is the Most Probable Value (MPV) of the ADC distributions for such events. The MPV's are then subjected to corrections for the temperatures and the pre-determined Performance Ratio (PR) of the individual tiles in each tower. The corrected MPV's determine the gain of each tower. We will use these data to calibrate the response and to ensure the uniform performance of the towers. |
Saturday, October 29, 2022 3:12PM - 3:24PM |
LC.00007: Calibrated Cosmic Muon simulations for the sPHENIX Hadronic Calorimeters Shuhang Li, Hanpu Jiang, Emma McLaughlin, Blair D Seidlitz, William A Zajc, Stefan Bathe, Daniel Richford The sPHENIX detector at BNL's Relativistic Heavy Ion Collider (RHIC) will start data taking in 2023 and seeks to understand the microscopic properties of the Quark-Gluon Plasma(QGP), by performing high precision measurements of jets and heavy flavor observables. Critical to full jet reconstruction is the sPHENIX hadronic calorimeter (HCal) system, which will be the first calorimetric hadronic measurements made at RHIC. To do this, the HCal needs to be properly calibrated prior to and during the data taking to measure the energy deposition of jets. This talk will present the GEANT4 study with a cosmic muon generator with a realistic zenith angle and energy distribution to investigate the possibility of using cosmic muon events as a calibration source for the hadronic calorimeters (HCal's) when the full sPHENIX apparatus is in its data-taking position. |
Saturday, October 29, 2022 3:24PM - 3:36PM |
LC.00008: Single particle energy scale calibration of the sPHENIX hadronic calorimeters Emma McLaughlin, Hanpu Jiang, Shuhang Li, Blair D Seidlitz, William A Zajc The sPHENIX detector, which will begin collecting data at RHIC starting in 2023, contains a three-layer calorimetry system, including two layers of hadronic calorimetry. These calorimeters will be essential in achieving precise jet measurements for probing the microscopic properties of the quark-gluon plasma. To extract useful data from these calorimeters, their energy scales must be well-calibrated as well as be checked for changes in calibration during sPHENIX run periods. One possible method for providing both absolute and relative calibration would be to use hadron showers from isolated single particles from p+p collisions. This talk will first discuss challenges facing a single particle energy scale calibration, most notably the rate of high-energy isolated single particle tracks that deposit a majority of their energy into a single or small range of hadronic calorimeter towers, and then propose methods of conducting this single particle calibration from Run-2 p+p sPHENIX data. Results from these methods on simulation data of p+p runs in the sPHENIX geometry using PYTHIA v.8 and GEANT4 will be presented. |
Saturday, October 29, 2022 3:36PM - 3:48PM |
LC.00009: Jets Substructure from Calorimeter Subjets in sPHENIX Noah J Applegate The use of jets as a probe in p+A and A+A collisions allows access to the interaction of partons produced in hard-scattering interactions with the nuclear environment and is sensitive to a wide range of scales. Measurements of jets and jet substructure in these systems will provide unprecedented access to details of partonic interactions with the nuclear medium. The sPHENIX detector currently under construction at Brookhaven National Laboratory's Relativistic Heavy Ion Collider (RHIC) is designed with complete hadronic and electromagnetic calorimetry, enabling precise studies of calorimetric jets substructure in ways previously inaccessible at RHIC, using anti-kT R=0.2 "subjets" as constituents to form larger R jets. |
Saturday, October 29, 2022 3:48PM - 4:00PM |
LC.00010: Measurement of Energy Correlators within jets in p+p Collisions at √s = 200 GeV in STAR Andrew Tamis Advancements in jet-finding algorithms allow for detailed studies into parton showers, fragmentation, and hadronization governed by Quantum Chromodynamics. Recent theoretical efforts in describing intra-jet energy flow propose a new obervable, the N-point energy correlator. This observable recontextualizes jet substructure by providing insight into the perturbative structure of the jet as well as hadronization. From the two-point energy correlator as a function of opening angle, one can determine the crossover region where the scaling behavior of the correlator changes from a random distribution of hadrons at small opening angles to perturbative partons at large opening angles. |
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