Session EN: Instrumentation: Calorimeters

Manufacturing Scintillator Tiles for the STAR Forward Hadronic Calorimeter

Over the last 20 years, Relativistic Heavy Ion Collider (RHIC) experiments at Brookhaven National Laboratory have studied the strong interaction through collisions between subatomic particles and nuclei. As the only running experiment at RHIC, the Solenoidal Tracker at RHIC (STAR) plays a leading role in providing information regarding proton structure, properties of the constituents, and their interactions. The STAR Forward Upgrade will enhance its capabilities by creating new low-angle subsystems, including a forward hadronic calorimeter system (HCal). The HCal will enable new low-angle measurements at STAR, including forward jet, dijet, and hadron-in-jet production. The manufacturing of plastic scintillator tiles for HCal is shared between Abilene Christian University (ACU), Ohio State University, and UCLA. ACU’s manufacturing process entails cutting, milling, and polishing each tile. This process has been designed and tailored to the facilities and specifications of the material. The details of ACU's manufacturing process and the current status of the manufactured scintillator tiles will be presented.   

Performance Characterization Studies of sPHENIX Hadronic Calorimeter Scintillating Tiles

sPHENIX is an experiment currently being built and will be installed at the Relativistic Heavy Ion Collider of Brookhaven National Lab. sPHENIX will measure jets and upsilons in Au+Au collisions of 200 GeV and is composed of a tracking and calorimeter system that includes a hadronic calorimeter (HCal) of two radial segments. The inner HCal will sit inside a 1.4T superconducting solenoid magnet, and the outer HCal will sit outside the magnet. Plastic scintillating tiles are sandwiched in between absorber plates running parallel to the beam direction and angled so that a particle exiting the interaction point hits four absorber plates. The HCal tiles and their respective SiPM signals are aggregated into a single calorimeter tower. Each towers’ batch of tiles will have a similar behavior to optimize the HCal’s performance. To achieve this, a performance characterization of each tile will be done by analyzing the tiles’ response to cosmic rays. The cosmic ray study results will also be used in conjunction with beam test results from an sPHENIX calorimeter system prototype to calibrate the HCal. This talk focuses on the testing and analysis procedure of the HCal scintillating tiles and their performance characterization results that will aid in the sPHENIX HCal system calibration.   

Ionizing Laser System for Calibration in the sPHENIX TPC

The sPHENIX detector is currently being built at RHIC in order to study the properties of quark gluon plasma caused by heavy ion collisions. This is done by measuring the upsilon states and jets formed from these collisions. To reconstruct these observables, sPHENIX will use a Time Projection Chamber (TPC) as its central tracker, which will measure the charged particle tracks. An issue inherent to a TPC is space charge, which distorts the field lines in the TPC, causing the apparent path of the tracks to change. A compact, steerable, ionizing laser calibration system will be used to provide a known track that allows us to study the evolving components of the distortion throughout the TPC. The laser is sent through a quartz bar as it enters the TPC, where it is directed with total internal reflection. By changing the angle that laser enters the quartz bar, we can shine the laser at almost any angle in the TPC, greatly improving the abilities of the calibration. I will discuss the design of the laser system and studies of its performance.   

Prototyping Electromagnetic Calorimeter for STAR Forward Calorimeter System using Au + Au at √s = 200GeV data

The STAR forward upgrade program is motivated 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 region including the Forward Calorimeter System (FCS). $\pi^{0}$ reconstruction was developed using a prototype of Electromagnetic Calorimeter (ECal) of the FCS using Au + Au collision at $\sqrt{s} = 200 GeV$ data collected during the 2019 RHIC run. We present this analysis to obtain the gain factors and invariant mass $\pi^{0}$ reconstruction using two different methods (cluster finder method and point maker method) to isolate the two photon candidates of the $\pi^{0}$.   

Calibration techniques for the STAR Forward Electromagnetic Calorimeter

The STAR Collaboration at RHIC is installing a forward detector upgrade in preparation for the 2021 $_{\mathrm{\surd s}}=$500 GeV p$+$p run. The new instrumentation, comprised of an electromagnetic calorimeter (ECAL), a hadronic calorimeter (HCAL) and a combination of small strip thin gap chamber and silicon microstrip tracking detectors, will allow for the full reconstruction of jets in the region spanning a range of 2.5 - 4 in pseudorapidity . These jets will provide access to low-x gluon helicity and high-x quark transverse momentum dependent parton distribution functions. Prototypes of the HCAL and ECAL were positioned at STAR during the 2019 run. Ongoing efforts to calibrate the ECAL using minimum ionizing particles will be presented.   

Zero-Suppression in sPHENIX Calorimeters

The sPHENIX experiment at the Relativistic Heavy Ion Collider is currently scheduled to begin taking data in 2023. sPHENIX is designed to collect data at up to 15 kHz to sample jets, photons, Upsilons, and heavy flavor hadrons with high statistics in proton-proton, proton-nucleus, and nucleus-nucleus collisions. The calorimeter system, which consists of a compact electromagnetic calorimeter and two longitudinal segments of hadronic calorimeter, will be read out with custom digital electronics. Removal or reduction of data content for towers with low energies, or zero suppression, is critical to meet the required data rates. We detail results of sPHENIX GEANT detector simulations and alternative zero suppression algorithms to meet this requirement.   

Characterization of Zero-Suppression in sPHENIX Calorimeters and its Impact on Topological Clusters

The sPHENIX experiment at the Relativistic Heavy Ion Collider will begin data-taking in 2023. Decisions related to triggering, readout, and reconstruction can have a large effect on the ultimate experimental precision of the sPHENIX calorimeters. The reconstruction of 3-D topological clusters in the analysis of electromagnetic and hadronic particle showers associate energy deposits arising from the same particle and distinguish them from background noise. During data-taking, a complete readout of the 27,000 channels in the electromagnetic and hadronic calorimeters cannot be executed, so a zero-suppression scheme is necessary. We perform detailed GEANT4 studies of the calorimeter response to photons, hadrons, and jets under different simulated electronic noise scenarios and zero-suppression schemes. We study the impact of zero-suppression schemes on the topological cluster performance.   

Forward Physics with the MPC-EX+MPC Detector with RHIC-PHENIX

Measurements of the gluon wavefunction of a nucleus at low momentum fraction can help our understanding of QCD evolution. It is also an important input for interpreting the formation of the Quark-Gluon Plasma (QGP) observed in heavy ion collisions and the possible formation of QGP droplets in asymmetric ion collisions. Late in the PHENIX data-taking campaign a Si-W preshower, the MPC-EX, was added to the existing forward muon pison calorimeter extending the ability to separate $\pi^{0}$ decay photons to very high energy. Particles entering the preshower + calorimeter at 3.0 $<$ $\eta$ $<$ 3.8 can originate from a high-$x$ parton in the beam with a low-$x$ gluon in the target nucleus. In this talk we outline the current performance of the detector in the 2016 $d$+Au $\sqrt{s_{_{NN}}}$ = 200 GeV collision data and the current and near-future prospects of measurements with this detector and their impact on our understanding of the gluon wavefunction of the nucleus.