Bulletin of the American Physical Society
2019 Fall Meeting of the APS Division of Nuclear Physics
Volume 64, Number 12
Monday–Thursday, October 14–17, 2019; Crystal City, Virginia
Session GL: Instrumentation: Detectors for Heavy Ion Collisions |
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Chair: Sevil Salur, Rutgers University Room: Salon H |
Tuesday, October 15, 2019 2:00PM - 2:12PM |
GL.00001: The STAR iTPC Upgrade Irakli Chakaberia Run-19 of the Relativistic Heavy Ion Collider marked the beginning of the Beam Energy Scan phase II (BES-II). The BES-II program has been inspired by the success of the first phase of the beam energy scan (BES-I). The goal of the BES-II is to accumulate a larger data-set to obtain experimental measurements with higher statistical precision and thus turn trends and features found during the BES-I into definitive conclusions and new understanding. With this goal in mind, STAR has undergone several substantial upgrades in preparation for the BES-II. One of the major upgrades is the installation of the new inner TPC sectors (iTPC). The iTPC brings wider pseudorapidity coverage $|\eta| < 1.5$ and increased reach to lower $p_T$ down to 60 MeV$/c$. In addition, it provides improved $dE/dx$ and $p_T$ resolution, and therefore better particle identification capabilities. In this talk I will report the results of the iTPC upgrade and its successful commissioning with the cosmic ray data-taking ahead of the Run-19. I will conclude by showing its status and performance during the low energy Au+Au collisions in the Run-19. [Preview Abstract] |
Tuesday, October 15, 2019 2:12PM - 2:24PM |
GL.00002: Development of the readout electronics for the sPHENIX Time Projection Chamber Klaus Dehmelt The sPHENIX experiment at RHIC is the repurposed experiment of the PHENIX experiment that ended data taking in 2016. The sPHENIX is aiming for measuring Jets and Quarkonia at RHIC energy where the strongly coupled Quark Gluon Plasma (QGP) is formed. In order to separate Upsilon states, a tracking device that can handle a few hundreds kHz collisions and keep a 100MeV mass resolution. Therefore, we have decided to build a a time projection chamber without gating grid. The signal charge has to be readout continuously which required a new readout electronics. In the new readout scheme, the signal is readout by 624 Frontend cards that have 8 SAMPA v5 chips, the new version of the one employed for ALICE TPC, and sent to a backend electronics, FELIX PCI card, designed for ATLAS experiment. The data rate from the whole TPC may reach as much as 1.4Tbps. We will show the readout scheme for the TPC and the performance from the prototype boards. [Preview Abstract] |
Tuesday, October 15, 2019 2:24PM - 2:36PM |
GL.00003: Upgrade of the ALICE Time Projection Chamber Austin Schmier The ALICE Time Projection Chamber (TPC) is a gaseous drift chamber used to study proton-proton and heavy ion collisions at the large hadron collider (LHC). The LHC is currently undergoing a major upgrade that will increase the event rate from 1 kHz to 50 kHz and the TPC is therefore being upgraded to handle the increased event rate. The current ALICE TPC uses multi-wire proportional chambers in conjunction with a gated grid to reduce ion backflow, which limits readout to \textasciitilde 3 kHz. There is a readout deadtime of roughly 400 \~{a}\v{Z}\texttwosuperior . The new design will use gaseous electron multiplier (GEM) foils, allowing for reduced ion backflow and a continuous readout, meeting the 50 kHz requirement. The TPC upgrade will also require 3,600 new front end cards (FECs), each with 128 channels, in order to read the signal from the GEM foils. The FECs amplify, shape, digitize, process, and buffer the signals from the TPC. The physics motivations for the upgrade and the current progress of the construction and testing of the upgraded TPC will be discussed. [Preview Abstract] |
Tuesday, October 15, 2019 2:36PM - 2:48PM |
GL.00004: ABSTRACT WITHDRAWN |
Tuesday, October 15, 2019 2:48PM - 3:00PM |
GL.00005: Measurement Results for Micropattern Gain Structures for Use in High Rate TPCs Caitlin Beattie, John Harris, Richard Majka, Nikolai Smirnov Time Projection Chambers (TPC) are often the preferred choice for central tracking and particle identification in high luminosity colliding beam experiments. A major consideration in such an environment is minimization of back flow of positive ions from the gain element into the main drift volume. This ion back flow (IBF) can lead to space charge build up in the main drift volume that will distort the drift field and the resulting measured tracks. The traditional method of controlling IBF using a grid as a gate necessitates triggering the TPC which is inconsistent with modern physics goals requiring very large data sets. We present our investigation of IBF measurements for a variety of gas mixtures, electric fields, and micropattern structures (four gas electron multipliers (GEMs), and two GEMS plus micromegas) used as the amplification region. [Preview Abstract] |
Tuesday, October 15, 2019 3:00PM - 3:12PM |
GL.00006: Passive Gating Grid Studies for a Time Projection Chamber Prakhar Garg A Time Projection Chamber (TPC) is often the main tracking device in many experiments. A TPC measures space points of charged tracks to provide momentum resolution and particle identification for a variety of measurements. In high multiplicity environments, a TPC has to cope with the build-up of space charge in the drift volume form two main sources: primary ionization and Ion Back Flow (IBF) from an amplification device. One can only concentrate on combating IBF, which can be accomplished with appropriate voltages briefly grid to absorb all charges. However, this limits the operation to low readout rates. To overcome this problem, Micro-Pattern Gas Detectors (MPGD) will be implemented in future TPCs. MPGDs are inherently capable to reduce IBF, yet not to an optimum level. A passive or statically powered gating grid might enhance the IBF reduction. We have simulated woven wire meshes, different patterns of etched meshes, hexagonal micro-pattern meshes and static bi-polar wire gating grids. We have studied several options to achieve good electron transparency for the primary electrons and high blocking for the ions coming from the amplification stage. In this presentation, we will discuss our results and provide techniques for overcoming IBF. [Preview Abstract] |
Tuesday, October 15, 2019 3:12PM - 3:24PM |
GL.00007: Test Beam Campaign with the sPHENIX TPC Prototype Henry Klest The sPHENIX experiment will utilize a Time Projection Chamber (TPC) as the central tracker. The goal of the TPC is to perform precise upsilon spectroscopy and jet measurements, both of which require high tracking efficiency and excellent momentum resolution. \newline The sPHENIX collaboration produced a small-scale prototype TPC that features a full-sized version of the readout module and the nearly final readout electronics. This prototype was tested at Fermilab using a beam of 120 GeV protons. The results of this test-beam campaign will be discussed in this presentation. [Preview Abstract] |
Tuesday, October 15, 2019 3:24PM - 3:36PM |
GL.00008: Studies of a Central Membrane for the sPHENIX TPC Sourav Tarafdar sPHENIX is a future experiment at RHIC to measure jets and Upsilons for investigating the properties of the quark-gluon plasma formed in heavy ion collisions. As the central tracker it will feature a Time Projection Chamber (TPC) that is used to measure charged particle tracks. The TPC is sandwiched in between inner tracking detectors and electromagnetic and hadronic calorimeters and also a 1.4 Tesla superconducting solenoid magnet. The TPC will be equipped with micropattern gas detectors for providing the space point resolution and reducing the space charge problem inherent to a TPC. The TPC will also depend on a central membrane which is substantial for supplying a uniform drift field amongst others. \\ A variety of simulations with different designs of the membrane have been performed ranging from the investigation of the tracking performance to jet fragmentation. In this presentation we will discuss these extensive studies. [Preview Abstract] |
Tuesday, October 15, 2019 3:36PM - 3:48PM |
GL.00009: R&D studies of a small-strip thin gap chamber as a STAR forward tracker Prashanth Shanmuganathan The STAR experiment at the Relativistic Heavy Ion Collider is en route on a forward upgrade to address open questions in the QCD physics in very low and very high Bjorken-$x$, during $p$+$p$ and $p$+Au collisions planed in the years 2021 and beyond. Measurements from Au+Au collisions will enable to probe the longitudinal structure of the nuclear initial state as well as transport properties. The detector upgrades, the Forward Calorimeter System and the Forward Tracking System, provide precise identification of pions, photons, electrons, jets and as well as hadrons in the pseudorapidity region 2.5 to 4. The forward tracking system is a combination of silicon mini-strip detectors and small-strip thin gap chambers (STGC), which provide charge sign discrimination, and excellent photon and electron identification. STGCs are the variant of Multi-Wire Proportional Counters, which provides better spatial resolution at high particle flux regions. In between collision point and forward calorimeters four planes of STGC chambers are planed to be installed, and each plane contain two chambers to measure $x$-$y$ diagonal position for tracking. Two prototype chambers, each $(30\,cm)^2 \times 0.28\,cm$ was built.In this talk, we will present the test results from the R\&D studies. [Preview Abstract] |
Tuesday, October 15, 2019 3:48PM - 4:00PM |
GL.00010: Test Beam Results for a Spectator Reaction Plane Detector for Use at the CERN LHC Samuel Lascio, Alice Mignerey The ability to determine the reaction plane of a heavy ion collision using spectator neutrons is key to the study of directed flow and the chiral magnetic effect (CME) in these reactions. A shower max detector, the Spectator Reaction Plane Detector (SRPD) has been developed to map spectator neutron positions at zero degrees. The SRPD is comprised of a 4 x 4 array of 2 x 2 x 1 cm quartz elements. In this specific design the SRPD is positioned between two elements of a Zero Degree Calorimeter (ZDC). The detector performance was evaluated using a Pb beam at the SPS test beam facility at CERN. The results will be compared to a GEANT simulation of the detector for the specific test beam parameters, with implications for the design of a second generation detector for incorporation into a new ZDC for the CERN LHC Run 3. [Preview Abstract] |
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