Transcript mcppet_03_17

MCP-PET: Geant4 Simulation
• Geometry Implementations
1. Similar to the last report (polished surface).
Scintillator : LSO, LaBr3
# of layers : 5 -> 4
Area : 51x51mm -> 102x102mm
2. Wavelength shift plastics/optical fiber
Collect light on the side wall of X-tal.
Need input parameters for WLS plastics.
e.g) refractive index, absorption length,
emission spectrum, ..
• Surface condition( Ground -> Polished)
for total internal reflection.
4-Layer Micro-Pet Sampling Calorimeter
Layer
1
N. B.: NOT TO
SCALE
C
R
Y
S
T
A
L
C
R
Y
S
T
A
L
C
R
Y
S
T
A
L
C
R
Y
S
T
A
L
Layer 3
Layer 4
Samp
le
Cryst
al
MPC
Wave-Form
Sampling
Electronics
Layer
2
Transmission Line Anode
Legend
Wave Shifter
Photocathode
Bar
MCP Channel
plates Lines+ Fiber Optic
Transmission
Wave-Form Sampling Electronics
Wave Shifter + Fiber
Optic
MC
P
MC
P
MC MC
P
P
MC
P
M
CP
MC
P
MC
P
1a
1b
2a
3a
3b
4a
4b
2b
Emission Spectra(input to geant4)
LSO
LaBr3
MCP Q.E(Burle Planacon)
nm
nm
LSO
LaBr3
Light Yield
26,000/MeV
60,000/MeV
Decay time
40ns
20ns
Refractive index
1.88
1.82
Attenu. length
1.2cm
2.1cm
Photo-fraction
32.5%
15%
Peak wavelength
420nm
370nm
nm
Emission Spectra(geant4 output)
LSO
nm
Emission spectra of LSO, LaBr3
Before/After MCP Q.E applied
LaBr3
nm
# of photoelectron at photo-cathode
# of p.e ( LSO)
LaBr3
•# of p.e at 1st lalyer
•Sum of 2 sides( front and back)
•371 for LSO
976 for LaBr3( ~2.6 times larger than LSO)
•LaBr3 has more compton scattering events.
Hit layer(1,2,3,4)
1
2
LSO
3
4 layer
LaBr3
Shows that LSO has higher stopping power than LaBr3.
Detection Efficiency
?
LaBr3
# of photo-electron(LSO): sum of 4 layers
LSO
LaBr3
Layer 1
56.8
41.1
Layer 2
25.5
27.7
Layer 3
9.2
14.8
Layer 4
2.7
6.9
Sum
87.4(%)
78.9(%)
•Requiring
# of photo-electron > 50.
•Mutiple layers can
have hits in an events.
( by compton scattering)
Light spread( at photo-cathode)
X of p.e ( Single event)
mm
mm
RMS of the X spread
Light spread : RMS ~ 4.5mm
Consistent with simple calculation:
crystal length : 10mm
rindex : 1.82(LSO) -> 1.00
critical anlge : 33.3 deg
10mm*tan(33.3) = 6.5mm
X of p.e ( all the first layer hits)
Plans
• Investigate material effects
4mm of T-Line width.
• Extract Energy, Timing resolution
• Implement WLS bar/ fiber