Linear Collider GEM TPC R

1
Linear Collider GEM TPC RD
University of Victoria
The challenge
The concept

• TPC with GEM readout
• Solenoid field 3-4 T

cm
Victoria prototype
cm

• 30 cm drift
• double GEM

GEMs being mounted
Readout Pad Layout
Each pad is assigned a value for estimated number
of electrons based on size of pulse.
Arrival time on each pad is also measured.
Number of electrons
Arrival time
2
Linear Collider GEM TPC RD
University of Victoria

• The track fit has four parameters
• X0 (the x position of the tracks center
• Phi (angle of track relative to vertical)
• Sigma (track width)
• 1/r (inverse of the radius of curvature)

Sample tracks in P5 gas in various magnetic
fields (25 cm drift distance)
Magnetic field tests
B2.5 T
B4.5 T
B0 T
B0.9 T
Diffusion decreases with B-field
TRIUMF (Vancouver) 1 telsa
Resolution Study
Transverse track resolution

• Resolution improves with B-field up to 1.5T
• Above 1.5T no significant change
• Simulation shows better resolution for high fields

Resolution (mm)
Goals
original
new
3cm
30cm