Tracking Issues in the Central Region Craig Woody BNL DC Upgrade Meeting August 11, 2002

C.Woody, DC Upgrades Meeting, 8/11/042  PHENIX would benefit greatly by implementing a tracking system inside the central magnet: Improved momentum resolution Reduced background from decays and conversions Improved vertex tracking capabilities when used in conjunction with the VTX Improved pattern recognition when used in conjunction with the HBD  We would also benefit greatly by expanding our tracking coverage beyond the present PHENIX acceptance in both   and f. This is particularly important if we want to study jets and do g -jet correlations.  The problem is with implementing a tracking system that will cover h ~ 1 due to the limited space for all detectors in the central region. General Comments

C.Woody, DC Upgrades Meeting, 8/11/043 h=1.17 h=0.88 h=0.70 h=0.35 Central Region Planar GEM Tracking chambers Provides tracking coverage over -2.6 < h < 2.6 h = 2.6 Space for the TPC is being squeezed by the need to bring out services for the VTX and the need for space for the readout electronics cm

C.Woody, DC Upgrades Meeting, 8/11/044 Nose Cone Calorimeter Tracking in front of the NCC would provide clean separation of charged and neutral showers Missing rapidity coverage NCC ~ 1 m dia Area ~ 0.8 m 2 2 detectors x 2 sides  GEM area = 4 x 0.8m 2 =3.2 m 2 Two barrel detectors would add ~ 10m 2 Total GEM area for HBD ~ 1 m 2 Would also provide tracking in a region of rapidity not presently covered in PHENIX E.Kistenev

C.Woody, DC Upgrades Meeting, 8/11/045 COMPASS GEM Detectors COMPASS tracking system includes a set of 20 triple GEM detectors (31x31 cm 2 ) each 2D readout using Microstrips Problems with occupancy for PHENIX ? We may want to use a “Micropad” readout similar to what is being proposed for the Forward Silicon Position resolution comparable to Si detectors s ~ 46 m m

C.Woody, DC Upgrades Meeting, 8/11/046  STAR is planning to implement a large (~ 10m 2 ) GEM tracking system in their forward direction.  There is a world-wide problem in obtaining GEM foils from CERN due to their limited production capacity (large demand from LHC-B may limit world supply for the foreseeable future)  We (PHENIX/BNL) have been collaborating with CERN, MIT and Yale on developing a new commercial source of GEM detectors (Tech Etch in Plymouth, MA)  MIT has also been developing a GEM readout system based on the COMPASS readout chip. STAR/MIT GEM Development

C.Woody, DC Upgrades Meeting, 8/11/047 Comparison of CERN, 3M and Tech Etch Foils Measurements taken w/ Fe-55 source Field config. DG: 0.4kV/cm TG 1: 2.5kV/cm TG 2: 3.0kV/cm IG: 3.5kV/cm B.Azmoun

C.Woody, DC Upgrades Meeting, 8/11/048 Gain Stability of GEM Foils Gain instability appears to be a charging effect in the foils due to materials or process used by different manufacturers B.Azmoun

C.Woody, DC Upgrades Meeting, 8/11/049 Comparison of Tech Etch and CERN Foils

C.Woody, DC Upgrades Meeting, 8/11/0410 APV25 Readout Chip Developed for CMS Silicon strip detector Used by COMPASS for reading out GEMs Bernd Surrow / MIT

C.Woody, DC Upgrades Meeting, 8/11/0411  STAR is planning to install a set of three small (10x10 cm 2 ) triple GEM tracking detectors in their forward region possibly as early as Run 5 with a complete readout system based on the APV25 chip (future plans are for a large, 10 m 2 system)  Is a system like this of interest to PHENIX ?  Can we provide enough space in the central region to implement a large acceptance tracking system (either with a TPC or with a system of planar GEM tracking detectors) along with all of the other detectors (and their services) that are planned to go into this region ?  If we’re interested in this, we need to start doing some serious simulation work on how such a tracking system would perform. Future Steps ?