1. Jim Pinfold & Yushu Yao Mar. 27, 2007
Simulation of Quartic
Jim Pinfold & Yushu Yao
Mar. 27, 2007

2. Outline Simulation Setup Some Pictures
Result of Simulation (rise time, #PE)
TO DO

3. Simulation Setup 4 by 8 array of quartz bars Bar size 6 by 6 mm
Al Gap between and around bars
Aluminized walls and bottoms (a standard al reflectivity curve is included, 95% above 300nm, drop exponentially below)
Detectors(PMT) at the flat end
PMT efficiency not included
PMT

4. Some Pics

5. Path of Proton and Lights
A proton coming from the IP hit the longest bar first in the direction shown as in the graph.
The proton pass through the centre of one array of 8 bars
proton
proton

6. #Photons Generated and Detected
Total 8 bars there are on average 6500 photons generated in fused silica, per channel
90% of them lost in the reflection and absorption
Total 8 bars there are ~650 photons reach the PMT, per channel
Assuming a 20% efficiency of PMT, each channel expect Photon electrons
Why a range (12-16) instead of a number? See next page
#Photons
Generated
In All 8 Bars
#Photons hits
In All 8 Bars
Photons Directly
From Proton
#Photons hits
In All 8 Bars
All Photons

7. Dist of Photons Detected
Dist of # Photons Arrive at the detector
xyz are redefined for clearer illustration
x dist is a single peak because the detector is at the same x position
z dist is flat over 6mm range
In y dist one can see the layout of the channels, the channels near IP collect less light because the bar is longer and the absorption loss is stronger.
X Dist
Z Dist
Y Dist y x z
Proton Direction

8. Time Dist / Wavelength Wavelength (nm) T, ns Arrive Time Dist
All 8 Bars
Arrive Time Dist
Longest Bar
Arrive Time Dist
Shortest Bar
T, ns

9. Rise Time with all 8 bars t=8ps -10ps Previous Page
In the time/wavelength plots, darker color means more photons in this time/wavelength region. The photons arrive at the PMT first are the more reddish photons. Which means the detection of UV is not critical in the determination of rise time
Not much difference between the shortest and longest bars except the longest bar has a longer tail due to the longer travel time of higher frequency photons
Left Plot:
Enlarged plot of the Bottom-Left plot in previous page
The rise time is determined from the start of the rising to the middle of the peak height
The rise time is around 8-10 ps
t=8ps
-10ps

10. Conclusion and TODOs Expect 12-16 P.E. per PMT channel
Rise time 8-10 ps
TODO
Add PMT Quantum Efficiency