General GEM Information

NIM Papers
- GEM: A new concept for electron amplification in gas detectors, F. Sauli
- Performance of triple GEM tracking detectors in the COMPASS experiment, Ketzer et al.
PDG Accelerator Detector Review (See Section 28.6.3)
Super BigBite CDR

Presentations

http://www.jlab.org/~cisbani/SBS_Tracker.pdf

GEM Detectors for PREX

Configuration

The GEMs were mounted in an XY XY XY XY configuation on April 14. Our best guess at positions (from Dustin) in the rotated coordinate system are:

Detector	Orientation	z (m)
Bottom UVA	XY	1.15
Top UVA	XY	1.15
Bottom INFN	XY	1.4
Top INFN	XY	1.4

Chambers are placed orthogonal to the z axis.

HV Adjustment

Individual chamber HV is controlled through a CAEN N1471 NIM module. It can be remotely controled through minicom on ahut. The channel mapping is

http://www.jlab.org/~adaq/halog/html/1004_archive/100414225720.html

Channel	Cable	Detector
0	7	Top UVA
1	8	Bottom UVA
2	FPP7	Top INFN
3	FPP6	Bottom INFN

Gas configuration

The gas is presently a 80-20 Argon/CO2 mix (or 70/30?).

Replaying Data and Software

Replaying data can be done on any of the adaq machines. Simply do

goprex
analyzer prex_gem_L.C

and enter in the run number and number of events you would like to analyze. The database for the GEMs is in the $DB_DIR directory. This replay uses the TreeSearch-GEM library for GEM decoding, clustering, and tracking maintained by Ole Hansen.

Replayed files go in the rootfiles directory and are named

prex_gem_L_xxxxx.root

Run List

PREX GEM Runs

Work to Do/Main issues

HV Scan
- GEM HV Scan Runplan

Pedestal analysis (Francesco Cusanno)
- Stability
- Event-by-event corrections algorithm
- Higher order event-by-event corrections
- HV/Rate dependence
- Pedestal value/widths to find bad channels

Cluster Analysis
- Multiple cluster propagation across planes
- Clusters energy association between planes, noise evaluation

Position Resolution (Ozgur Ates)
- Evaluate plane resolution
- Different ways to utilize energy information to maximize resolution(?)

Efficiency/Gain Analysis (Kiad)
- Evaluate hit efficiency vs. ADC cuts
- Efficiency, gain vs. strip
- Efficiency, gain vs. HV
- Gain differences in readout planes