Transcript TKR trigger simulation

TKR trigger simulation
(timing study)
M. N. Mazziotta
(LAT-TD-01128)
Udine, January 30-31, 2003
Aim of this work
Requirements for the hardware design:
1. Trigger delay to latch the discriminator output
2. Trigger efficiency vs threshold and coincidence
window
3. Hit capture efficiency vs delay and threshold
Applications:
1. Detector acceptance calculation
2. GRB time detection
3. ....
Simulation code
GEANT 3.21: geometric description and tracking
• 4 middle trays (4 x-z layers and 4 y-z layers)
HEED: Si energy loss and e-h pairs production
• Front end electronics simulation (transfer function)
• Induced current calculation (Ramo’s Theorem)
Timing studies
Vth
TOT
T1
T2
time
The threshold value has been set at a fraction of Vmip.
Trigger timing
Trigger: 6-fold coincidence of the first 3 x-z and 3
y-z fired planes
Coincidence window = 1 s (one shot)
Tc (time coincidence) = the last T1 of the triggered
planes
Tf (trigger falling edge) = the first T2 of the
triggered planes
Time coincidence width = Tf-Tc
Trigger timing
T1
T2
T1
T1
Tc
T2
T2
Tf
Timing studies: 1 GeV muons
Strip signals:
Vth=1/4Vmip
Timing studies: 1 GeV muons
Plane signals:
OR of the
strips in the
plane
Timing studies: 1 GeV 
Plane signals:
OR of the
strips in the
plane
Two peaks!
Trigger timing: 1 GeV muons
Trigger timing: 1 GeV 
Hit capture efficiency
T2-Tc = time interval when the strip signal is over the
threshold (respect to the trigger time Tc).
Td = time interval between the trigger and the hit
capture time (delay)
The hit is “captured” if Td < T2-Tc
The efficiency as a function of Td is evaluated from
the cumulative distribution of T2-Tc
1 GeV muons have been simulated at zenith angles 0º,
10º,20º,30º,40º and uniformly distributed in azimuth
Hit capture efficiency:  1 GeV
Trig to TKR
Tc
Hit capture efficiency:  1 GeV =40°, =0°
Trig to TKR
Tc
Hit capture efficiency:  1 GeV =0°:
threshold scanning
Trig to TKR
Tc
Hit capture efficiency:  1 GeV =40º:
threshold scanning
Trig to TKR
Tc
GLEAM
Future plans
GLAST
DIGI
HIT
(rin, rout, E)
Timing
analysis
DIGIT
TkrTrig
(fired strips,
ToT per layer)
L1T
Preliminary results (2 GeV , =0°)
Plane signals:
OR of the
strips in the
plane
Preliminary results (2 GeV , =0°)
Preliminary results (2 GeV , =0°)
Trig to TKR
Conclusions
 A trigger timing study has been performed on a mini
TKR tower consisting of 4 middle trays
 The trigger hit capture efficiency has been also
evaluated
To evaluate the trigger efficiency a simulation on
the whole TKR system is needed: GLEAM era!
(people: M.N.M., M. B., F. L., F. G., N. G.)