N4A4  Gaseous Detectors: R&D II

Thursday, Nov. 5  08:30-10:10  Pacific Salon 1&2

Session Chair:  ANNA COLALEO, INFN-Bari, Italy; Bruno Guerard, ILL, France

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(08:30) N4A4-1, Performance of a Quintuple-GEM Based RICH Detector Prototype

M. Blatnik1, K. Dehmelt1, A. Deshpande1, D. Dixit1, N. Feege1, T. K. Hemmick1, B. Lewis1, M. L. Purschke2, W. Roh1, F. Torales-Acosta1, T. Videbaek1, S. Zajac1

1Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY, USA
2Physics Department, Brookhaven National Laboratory, Upton, NY, USA
Cherenkov technology is one of the first choices for particle identification in high energy particle collision applications. A challenging part is the deployment in the high pseudorapidity (forward) direction where particle identification must allow for high lab momenta, up to 50 GeV/c and more. In this region Cherenkov Ring-Imaging is among the most viable solutions and will provide the desired performance if the radiator has a low index of refraction, high yield of photons and subsequently photoelectrons, and allows precise measurement of the position of each photoelectron. A RICH gas detector prototype based on a novel concept with a significantly shorter radiator length compared to conventional RICH detectors has been constructed and tested. The setup and the results obtained are described.

(08:50) N4A4-2, A Prototype Combination TPC Cherenkov Detector with GEM Readout for Tracking and Particle Identification

C. Woody1, B. Azmoun1, M. Phipps1, M. Purschke1, N. Smirnov2, R. Majka2

1Physics, BNL, Upton, NY, USA
2Physics, Yale University, New Haven, CT, USA
A prototype detector is being developed which combines the functions of a Time Projection Chamber for charged particle tracking and a Cherenkov detector for particle identification. The TPC consists of a 10x10x10 cm3 drift volume where the charge is drifted to a 10x10 cm2 triple GEM detector. The charge is measured on readout plane consisting of 2x10 mm2 chevron pads which provides a spatial resolution ~ 100 microns per point in the chevron direction along with dE/dx information. The Cherenkov portion of the detector consists of a second 10x10 cm2 triple GEM with a photosensitive CsI photocathode on the top layer. This detector measures Cherenkov light produced in the drift gas of the TPC by high velocity particles which are above threshold. CF4 is used as the drift gas which is highly transparent to UV and provides excellent efficiency for detecting Cherenkov light. The drift gas is also used as the operating gas for both GEM detectors. The prototype detector has been constructed and is currently being tested in the lab with sources and cosmic rays, and additional tests are planned to study the detector in a test beam. This paper will describe the current status of the prototype along with results from some of these tests. This work is part of the Detector R&D Program for an Electron Ion Collider which could use a full scale version of a device such as this for tracking and particle identification at EIC.

(09:10) N4A4-3, R&D Status on GEM Detectors for Forward Tracking at a Future Electron-Ion Collider

A. Zhang1, V. Bhopatkar1, M. Hohlmann1, X. Bai2, K. Gnanvo2, N. Liyanage2, M. Posik3, B. Surrow3

1Department of Physics and Space Sciences, Florida Institute of Technology, Melbourne, FL, US
2Department of Physics, University of Virginia, Charlottesville, VA, US
3Department of Physics, Temple University, Philadelphia, PA, US
We report the status of R&D on large triple-GEM detectors for a forward tracker (FT) in an experiment at a future Electron Ion Collider (EIC) that will improve our understanding of QCD. We have designed a detector prototype specifically targeted for the EIC-FT, which has a trapezoidal shape with 30.1 degrees opening angle. A common GEM foil design is pursued to minimize NRE cost for foil manufacturing by a U.S. company (Tech-Etch, Inc.). Each group is investigating different detector assembly techniques and different signal readout technologies. The assembly techniques comprise a purely mechanical assembly method including foil stretching as pioneered by CMS (FIT group), gluing foils to frames that are held together with screws (U. Va. group) and gluing foils to frames that are glued together (TU group). The first two assembly techniques allow for re-opening chambers so that a GEM foil can be replaced if it is damaged. As for the readout technologies, we are pursuing a cost-effective one-dimensional readout with wide zigzag strips that maintains reasonable spatial resolution (FIT group), as well as two-dimensional readouts - one with stereo-angle (u-v) strips (U. Va. group) and another with r and ? strips (TU group). In addition, we aim at an overall low-mass detector design to facilitate good energy resolution for electrons scattered at low momenta. We will present design ideas for GEM foils and other detector parts with the goal to have the components entirely sourced by U.S. companies. This approach will be beneficial for other applications of large GEM detectors in the U.S.

(09:30) N4A4-4, Combined Gas Electron Multipliers and Micromegas as Gain Elements in a High Rate Time Projection Chamber

R. Majka

Physics Department, Yale University, New Haven, Connecticut, United States

On behalf of the RD-6/FLYSUB
A continuously sensitive high rate track imaging detector is highly desirable as a central tracking detector for a future electron-ion collider and a linear electron collider. A new generation of Time Projection Chamber (TPC) has been proposed for an ALICE (A Large Ion Collider Experiment at CERN) upgrade. Such a device would rely on the intrinsic ion back flow (IBF) suppression of micro-pattern gas detectors to minimize space charge build up in the main drift volume and thus would not require the standard gating-grid and the resulting intrinsic dead time. We have measured the properties of a combination of a micromegas (MMG) detector with two Gas Electron Multipliers (GEM) for such applications. We have measured the positive ion backflow and energy resolution of this structure at various settings of the gains of the elements and electric field between the elements with different working gases. We are able to reach ion back flow suppression of <0.35% at a total chamber gas gain of 2000 while maintaining an energy resolution of 12% (standard deviation) or better for the 55Fe x-ray.

(09:50) N4A4-5, Development of Resistive Micromegas for Sampling Calorimetry

T. Geralis1, M. Chefdeville2, M. Titov3

1Institute of Nuclear and Particle Physics, NCSR Demokritos, Athens, Greece
2LAPP, Annecy, France
3IRFU Saclay, Paris, France
Micromegas, a micro pattern gaseous detector, is proposed as an active medium for sampling calorimetry. Future linear collider experiments or the High Luminosity LHC experiments can profit from those developments for Particle Flow Calorimetry. Micromegas possesses remarkable properties concerning gain stability, reduced ion feedback, response linearity, adaptable sensitive element granularity, fast response and high rate capability. Recent developments on Micromegas with a protective resistive layer present excellent results, resolving the problem of discharges caused by local high charge deposition, thanks to its RC slowed charge evacuation. Higher resistivity though, causes loss of the response linearity. We have scanned a wide range of resistivities and performed laboratory tests with X-rays that demonstrate excellent response linearity up to rates of 10s of MHz/cm2, with simultaneous mitigation of discharges. Beam test studies at SPS/CERN with hadrons have also shown a remarkable stability of the resistive Micromegas and low currents for rates up to 5 MHz/cm2. We will be presenting results from the aforementioned studies as well as the potential in using Micromegas for sampling Calorimetry.