performance of shower maximum detectors
DESCRIPTION
Performance of Shower Maximum Detectors. Saori Itoh (Shinshu Univ.) GLC calorimeter group (KEK,Kobe,Konan,Niigata,Shinshu,Tsukuba). Introduction Detector construction Results of beam tests. 4cm. ShMax placed near the EM shower maximum. 1cm. Shower Maximum (ShMax) detector - PowerPoint PPT PresentationTRANSCRIPT
Performance ofShower Maximum Detectors
Saori Itoh (Shinshu Univ.)
GLC calorimeter group
(KEK,Kobe,Konan,Niigata,Shinshu,Tsukuba)
• Introduction• Detector construction• Results of beam tests
Shower Maximum (ShMax) detector (in the tile/fiber electromagnetic calorimeter)
HCAL
Tile/fiber EMCAL
Pre-Shower 4.3 X0
A tower of calorimeter
ShMaxplaced near the EM shower maximum
1cm
4cm
4cm
ShMax detector (in the tile/fiber electromagnetic calorimeter)
• Precise measurements of the incident positions of electrons and photons
• Electron/hadron separation
The requirement of position resolution is
Emm /3 (GLC Project Report, 2003)
Structure of ShMax detector
20cm
20c
m
y
x
20strips x 2 layers
z We use scintillator strips for ShMax detector.
A layer of ShMax detector consists of 20 scintillator strips.
We can measure energy deposit and determine the center position of EM shower.
We can measure the 2 dimensional position using 2 layers.
A strip size (1cmx1cmx20cm)
Center position of EM shower
ii
ii
i
E
ExCenter position of EM shower
Position of strip (Xi)
En
erg
y d
ep
osit
(E
i)
4GeV e
This shows energy deposit of each strip (Ei) as a function of strip position (Xi) for a 4GeV electron.
Using weighted mean, we can determine the center position of EM shower.
mips
strip number
APD APD
beam
Two types of ShMax detectorsMAPMT typeThrough an embeded WLS fiber, lights are read out byMulti-anode PMTs.
APD(Avalanche Photodiode) typeAPDs are directly attached at each side of strip. We can operate at room temperature.
HPK S8664-55Active area 5mmx5mm
beam
1 layer2 layers
APD typeMAPMT type
MAPMT
WLS fiber
APDAPD
2 layers 1 layer
Beam test @KEK 1-4GeV mixed beam
Pre-Shower(Pb 4mm+Scintillator 1mm) x 6 layers
• Position resolution• Electron/pion separation capability
T C C DC DC T ShMax
EMCAL
T : Trigger counterC : Cherenkov counterDC : Drift chamber
This shows the detector set up of beam tests.
From the data of beam tests, we analyze
Position resolutionMAPMT
WLS fiber
1 2 3 4 GeV incident beam energy
cm
0.3
1
Shower position – using DC position
Sh
ower
pos
itio
n c
m
using DC position
3.7mm
The correlation of the shower position of ShMax and the extrapolated position from DC
The distribution of their differences
The sigma gives position resolution
Position resolution as a function of the incident beam energy
4GeV e
Pos
ition
res
olut
ion
cm
cm
Position resolutionAPDAPD
cm
Sh
ower
pos
itio
n c
m
1
0.3 3.4mm
Position resolution as a function of the incident beam energy
The correlation of the shower position of ShMax and the extrapolated position from DC
The distribution of their differences
The sigma gives position resolution
4GeV e
Pos
ition
res
olut
ion
1 2 3 4 GeV incident beam energy
using DC position
Shower position – using DC position
cm
cm
e/pi separationMAPMT
WLS fiber
Energy deposit >20mipse-acceptance: 85%pi-rejection: 24 = 1/4.1%
The normalized distribution of energy deposit of pions and electrons (Sum of 2 layers)
energy deposit mips
acc
ept
anc
e
electrons
pions
Cut value
e/pi separation
0
0.2
0.4
0.6
0.8
1
1.2
0 5 10 15 20 25
APDAPD
Energy deposit > 8.5mipse-acceptance: 85%pi-rejection: 22 = 1/4.5%
The normalized distribution of energy deposit of pions and electrons (1 layer)
Cut value mips
electrons
pionsa
cce
pta
nce
2GeV
electrons
pions
Summary
• We tested two types of ShMax detectors.
• Position resolutions are about the same.
3.4mm ~ 3.7mm at 4GeV Without a gap, we can get better position resolu
tions.
• We can separate electrons from pions.
e-acceptance: 85%
pi-rejection: 22 ~ 24
Summary (cont’d.)
• Our R&D of ShMax detector will help for the new calorimeter model ( SiPM type ) with fine granularity.
• We need simulation to know the best segmentation of strip-array detectors.