Bulletin of the American Physical Society
APS April Meeting 2010
Volume 55, Number 1
Saturday–Tuesday, February 13–16, 2010; Washington, DC
Session X9: Instrumentation for Particle Physics III |
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Sponsoring Units: DPF Chair: Bruce Barnett, Johns Hopkins University Room: Maryland A |
Tuesday, February 16, 2010 10:45AM - 10:57AM |
X9.00001: Calibration of the CMS Hadronic Calorimeter with cosmic rays and early LHC beam data Steven Won We present an analysis of cosmic muon data (taken with and without magnetic field) and LHC early beam data taken in late 2009. Cosmic ray results provide invaluable validation of initial calibration and offer the possibility of verification of the absolute energy scale of the calorimeter, while LHC beam data allows measurement of the relative smoothness of energy deposited across the detector. These data represent the best and final opportunity to better understand the behavior of the detector, as the calibration constants extracted from this analysis will be used during the first year of data taking with collisions. [Preview Abstract] |
Tuesday, February 16, 2010 10:57AM - 11:09AM |
X9.00002: CMS HF PMT Abnormal Event Simulation Anthony Moeller Test beam results from 2004 showed that both muons and pions could penetrate through the entire Hadronic Forward (HF) calorimeter of the Compact Muon Solenoid (CMS), striking the PMT windows directly. The particles traveling through the window create Cherenkov radiation, depositing an abnormally large amount of energy compared to the energy collected from the HF. A detector simulation of HF created with Geant4 and CMS Software (CMSSW) was used to investigate this effect. Results for the particles used in test beam (electrons, muons and pions) are included. Also included are results from simple Pythia generated jets. Rates of abnormal events, timing information, as well as results from a few simple abnormal event rejection algorithms are presented. [Preview Abstract] |
Tuesday, February 16, 2010 11:09AM - 11:21AM |
X9.00003: A Novel Method to Eliminate Muon Events on PMT Windows of CMS Hadronic Forward Calorimeter Ugur Akgun The Hadronic Forward calorimeters in CMS use R7525-HA Hamamatsu PMTs for signal readout. Our previous studies revealed abnormally high amplitude signals due to punch through charged particles, mostly muons, producing Cherenkov photons at the PMT window. In this presentation we show that the Cherenkov signal coming from quartz fibers of the HF calorimeter has a pulse width of 4-5 ns while that of the Cherenkov signal created by muons at the PMT window is less than 2 ns. We also show that the signal from muon events arrive earlier than the usual HF signal. We propose the design of an additional circuit which can tag these events using these timing characteristics. [Preview Abstract] |
Tuesday, February 16, 2010 11:21AM - 11:33AM |
X9.00004: Study of CMS HF Candidate PMTs With Muons And \u{C}erenkov Light in Electron Showers Burak Bilki The response of four different types of PMTs to muons traversing the PMT window at different orientations is measured at CERN H2 test beam. These candidate PMTs for CMS HF upgrade show significantly lower response to PMT window incident muons compared to the currently installed HFPMT due to their thinner windows. For the four anode PMT, a simple and powerful algorithm to identify such events and recover the signal using the remaining quadrants is also presented. For the measurement of PMT responses to \u{C}erenkov light, the HF calorimeter signal was mimicked by two different setups in electron beams and the candidate PMT performances were compared with each other and with HFPMT. Superior performance of particular candidate PMTs was observed against HFPMT. [Preview Abstract] |
Tuesday, February 16, 2010 11:33AM - 11:45AM |
X9.00005: CMS Hadronic Endcap Calorimeter Upgrade Studies for SLHC ``P-Terphenyl Deposited Quartz Plate Calorimeter Prototype'' Warren Clarida The LHC is going to reach the designed value of 10$^{34}$cm$^{-2}s^{-1}$ in 2013. The LHC luminosity will continue to improve each year, reaching to 10$^{35}$cm$^{-2}$s$^{-1}$ in 2023. We call this high luminosity era the Super-LHC (SLHC). As the integrated luminosity of the LHC increases, the scintillator tiles used in the CMS Hadronic Endcap calorimeters will lose their efficiency. The CMS collaboration plans to substitute the scintillator tiles in the original design with quartz plates. Various tests have proved quartz to be radiation hard, but the light produced by quartz comes from Cerenkov process, which yields fewer photons than scintillation. To increase the light production, we propose to treat the quartz plates with radiation hard light enhancement tool, p-Terphenyl. The test beam studies revealed a substantial light production increase on pTp deposited quartz plates. We constructed a 20 layer calorimeter prototype with pTp coated plates, and tested the hadronic and the electromagnetic capabilities at the CERN H2 area. Here we report the results of these test beams as well as radiation damage studies performed on p-Terphenyl. [Preview Abstract] |
Tuesday, February 16, 2010 11:45AM - 11:57AM |
X9.00006: CMS Hadronic Endcap Calorimeter Upgrade Studies for SLHC ``Quartz Plate Calorimeter with Wavelength Shifting Fibers" Ugur Akgun Hadronic Endcap (HE) calorimeters of the CMS experiment cover the pseudorapidity range of from 1.4 to 3 on both sides of the CMS detector, contributing to superior jet and missing transverse energy resolutions. As the integrated luminosity of the LHC increases, the scintillator tiles used in the CMS Hadronic Endcap calorimeter will lose their efficiency. Here, we propose to replace the scintillator tiles in high radiation area with ``radiation hard'' quartz plates. To increase the light collection efficiency, the generated Cherenkov photons are collected by UV absorbing wavelength shifting (WLS) fibers. We constructed a 20 layer calorimeter prototype with WLS fibers embedded into quartz plates, and tested the hadronic and the electromagnetic capabilities at the CERN H2 area. We report the results of these test beams as well as the Geant4 simulations performed on the calorimeter prototype. We also discuss the radiation hard wavelength shifting fiber ideas. [Preview Abstract] |
Tuesday, February 16, 2010 11:57AM - 12:09PM |
X9.00007: Stability in the response of HFPMT as a function of magnetic field at the HF position, when CMS solenoid field is ramped up to 4 T Elif Asli Albayrak In the fall of 2008 CMS performed a system test, involving most of the sub-detectors, which aimed at operating its solenoidal magnet up to 4 Tesla. During this CRAFT tests, we have operated Forward Hadron Calorimeter system (HF) using LED signals. This was the first opportunity to check that the HF PMT were sufficiently shielded with respect to the CMS solenoid field at the position of HF. In this talk we present the comparison between the data collected at HF in presence of the magnetic field and with no magnetic field. The mean values and the RMSs of the LED signals for each HF PMTs remained unchanged in conditions with solenoid magnetic field up to 3.8 Tesla. At 4 T, HF PMTs are starting to be sensitive. Meanwhile, the fringe field around the HF PMTs are measured and will be presented. [Preview Abstract] |
Tuesday, February 16, 2010 12:09PM - 12:21PM |
X9.00008: Construction and Performance of 64-channel Gas Electron Multiplier (GEM) Prototype Using KPiX Analog Readout Chip Seongtae Park, Jacob Smith, Edwin Baldelomar, Clayton Wills, Mark Sosebee, Andy White, Jaehoon Yu, Kwangjune Park Since 1997, Gas Electron Multiplier (GEM) has attracted much attention in high energy particle detector development. The University of Texas at Arlington has been developing GEM detectors to use them as the sensitive gap detector for a Digital Hadron CALorimeter (DHCAL) which is going to be used in future experiments, such as those at the International Linear Collider (ILC). The detector structure and construction details are presented. A hybrid multichannel analog ASIC, KPiX, being developed by the Stanford Linear Accelerator Center team is used as the readout electronics for GEM detectors. Prototype detectors of 30cmx30cm have been tested with various radioactive sources, such as a Ru106 and Fe55, as well as cosmic rays. Results from analog signal testing and the radioactive source and cosmic ray data taking are presented. Finally the plans for 1x1 m$^{2}$ large GEM DHCAL planes will be presented. [Preview Abstract] |
Tuesday, February 16, 2010 12:21PM - 12:33PM |
X9.00009: Forward Physics with the CMS-CASTOR calorimeter Hans Van Haevermaet The CASTOR calorimeter, located at 14.4 from the CMS interaction point, enhances the hermeticity of the CMS detector by extending the rapidity coverage to $\eta < 6.6$. After having described the CASTOR calorimeter, examples of the capabilities and physics program of this detector will be presented. The study of forward jets production will give access to the low $x > 10^{-6}$ region where the gluon distribution increase is expected to saturate through the effects of nonlinear recombination terms in the DGLAP evolution equation. The study of events with a centrally produced dijet system and a forward jet will give access to parton dynamics beyond DGLAP and to the investigation of the BFKL or BFKL-like QCD evolution. The study of forward - central multiplicity correlations will enable to obtain a better understanding of the theoretically poorly constrained soft background that are the underlying events, defined as everything except the hard scattered components. The use of CASTOR as forward activity veto detectors is also of prime importance in the study of diffractive events, such as single diffractive $W$ production, in order to obtain a more powerful rejection of the non-diffractive and inelastic diffractive backgrounds. [Preview Abstract] |
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