Transcript スライド 1 - Hiroshima University

Photon Detector with
PbWO4 Crystals and APD Readout
APS “April” Meeting
in
Denver, CO
on
May 4, 2004
presented by
Kenta Shigaki
(Hiroshima University, Japan)
for the
ALICE-PHOS Collaboration
- Presentation Outline 

physics via photon channels at LHC-ALICE
calorimeters in relativistic heavy ion experiments
• working environments and performance requirements
• best scintillation crystal and readout device candidates

basic properties of key components
• PbWO4 crystals
• avalanche photo diode readout system

prototypes of PbWO4/APD calorimeter
• 1st stage prototypes – 33 assemblies
• basic properties of PbWO4 crystals and APD readout system
• 2nd stage prototype – 1616 assembly
• ALICE-PHOS performance evaluation

summary and outlook
May 4, 2004
Photon Detector with PWO and APD / APS Meeting in Denver / Kenta Shigaki
2
- Physics via Photon Channels at LHC-ALICE 
photons in relativistic heavy ion experiments
• vital probes of initial/hot/dense phase of collision system
• direct thermal photons
• photon HBT correlations
• jet quenching
• experimental virtues
• photons and neutral mesons measured in same detector
• particle identification to very high transverse momentum

photons: promising though difficult
• many interesting physics outcome at RHIC
• many more waiting at LHC
• even more powerful tool
• large direct photon rate up to ~ 100 GeV
• large neutral meson (“background”) suppression
May 4, 2004
Photon Detector with PWO and APD / APS Meeting in Denver / Kenta Shigaki
3
- ALICE Photon Spectrometer -
PHOS: high-granularity high-resolution photon spectrometer
• PbWO4 crystals with APD readout
• |h| < 0.5, Df ~ 100 degrees, 17,920 channels
• photons and neutral mesons
• -jet tagging
May 4, 2004
Photon Detector with PWO and APD / APS Meeting in Denver / Kenta Shigaki
4
- Calorimeters in Relativistic Heavy Ion Exp. 
working environments
• high particle multiplicity
• high particle spatial density
• possibly in (high) magnetic field

performance requirements
• high two-cluster separation capability with high granularity
• high energy resolution
• energy range from ~ 100 MeV to ~ 100 GeV

best scintillation crystal and readout device candidates
• PbWO4 (PWO)
• short radiation length
• small Moliere radius
• avalanche photo diode (APD)
• magnetic-field resistance
• compactness
May 4, 2004
Photon Detector with PWO and APD / APS Meeting in Denver / Kenta Shigaki
5
- Basics of PbWO4 Crystals 
dense, fast, radiation-hard inorganic scintillator
• density: 8.28 g/cm3
• radiation length: 0.89 cm (shortest as known inorganic scintillator)
• Moliere radius: 2.2 cm (smallest as known inorganic scintillator)
• suitable for high-granularity calorimeter
• refractive index: 2.3

only a few manufacturers available
• Furukawa (Japan), North Crystal (Russia), RI&NC (Belarus), …

optical and scintillating properties investigated
• transmittance
• scintillation light yield
• temperature dependence
• scintillation decay time
• ditto
May 4, 2004
Photon Detector with PWO and APD / APS Meeting in Denver / Kenta Shigaki
6
- Japanese PbWO4 Crystals 
manufactured by Furukawa, Co.
density 8.28 [g/cm3]
radiation length 0.89 [cm]
Moliere radius 2.2 [cm]
peak emission 420-440 [ns]
refractive index 2.3
Y-doped PbWO4
transmittance
measured with
Hitachi U3010
spectrophotometer
20 x 20 x 200 mm
ALICE-PHOS
operation point
light yield
May 4, 2004
ALICE-PHOS
operation point
mean decay time
Photon Detector with PWO and APD / APS Meeting in Denver / Kenta Shigaki
7
- PbWO4 Crystals from Other Manufacturers 
RI&NC Co. in Minsk, Belarus
• adopted by CMS
• investigated; similar properties as Furukawa’s
• ref. graduation thesis by K.Yokoyama
(available only in Japanese)

North Crystal Co. in Apatity, Russia
• adopted by ALICE-PHOS
• further tests at Hiroshima being prepared
May 4, 2004
Photon Detector with PWO and APD / APS Meeting in Denver / Kenta Shigaki
8
- Avalanche Photo Diode Readout System 
advantages over conventional PMT readout
•
•
•
•

magnetic-field resistance
compactness
low power consumption
high quantum efficiency
ALICE-PHOS choices
• APD: Hamamatsu S8664 (short wavelength enhanced type)
• basic properties investigated
• breakdown voltage
• inverse current
• pre-amplifier: Bergen/Hiroshima design
• final decision on rise time and power consumption soon
R 22
V+1 2
2 SC 3 7 3 5
Q2
1
3
R 38
22
2
C8
1 U /1 6 0 8
22
C 11
1 U /1 6 0 8
R 25
R 23
360
5 .1 K
C3
0 .1 U
V+1 2
V+1 2
CN1
R 36
1
2
3
4
5
6
BIAS
BIAS
22
OU T
TEST
-6V
BIAS
GND
+12V
OUT
TEST
3
R 35
1 0 0 M/2 1 2 5
53398-0690
Q1
2 SC 3 7 3 5
2
1
C9
0 .1 U
R 26
11K
1
2
D2
R D 3 .9 U M
R 24
1 0 0 M/2 1 2 5
V- 6
2 SA1 4 6 2
2
R 27
36K
1
S
2 SK9 3 2
C4
0 .1 U
C7
10P
D1
S8 6 6 4 - 5 5
1
R 29
22
3
2
3
Q6
1
2
Q3
2 SC 3 7 3 5
R 34
3
C2
1 0 N F/3 2 1 6
3
1
2
U1
D
G
2
Q4
2 SC 3 7 3 5
22
1
C6
C5
R 33
1P
R 28
TEST
OU T
3
1P
2 SC 3 7 3 5
2
47
Q5
1
1 0 0 M/2 1 2 5
R 30
8 .2 K( 4 .3 K)
R 31
11K
R 32
5 .6 K
R 37
22
C 10
0 .1 U
May 4, 2004
V- 6
Photon Detector with PWO and APD / APS Meeting in Denver / Kenta Shigaki
9
- PbWO4 EMC 1st Stage Prototypes 
base prototypes – 33 assemblies
• purposes
• basic properties of PbWO4 crystals
• R&D of APD readout system
• components
• PbWO4 crystals: Furukawa (Japan) / RI&NC (Belarus)
• PMT: Hamamatsu R1450
• APD: Hamamatsu S8664
• pre-amplifier: Hiroshima ver.1/2
• tests in Japan
• Tohoku-LNS (2002); photons at 0.8 – 1.2 GeV
• Hiroshima-REFER (2003); electrons at 150 MeV
• KEK-PS (planned in May/June, 2004); electrons at 1 – 3 GeV
May 4, 2004
Photon Detector with PWO and APD / APS Meeting in Denver / Kenta Shigaki
10
- PbWO4 EMC Basic Properties -



energy resolution sE/E = 2.5 %/E [GeV]  1.3 % with PMT
position resolution sx = 2.3 mm/E [GeV] with PMT
noise problem with APD at room temperature
counts [a.u.]
Etotal = 141 MeV
σ/Etotal = 7.3 % = 2.8 % /E
total energy [MeV]
May 4, 2004
Photon Detector with PWO and APD / APS Meeting in Denver / Kenta Shigaki
11
- PbWO4/APD EMC 2nd Stage Prototype 
second stage prototype – 1616 assembly
• purposes
• ALICE-PHOS performance evaluation and final design
• components
• PbWO4 crystal: North Crystal (Russia)
• APD: Hamamatsu S8664
• pre-amplifier: Hiroshima ver.2
• 64 channels in fast timing mode
• 192 channels in low power consumption mode
• cooled and stabilized at –25  0.1 ºC
• tests at CERN
• PS/SPS (2003): electrons and hadrons at 0.6 – 180 GeV
• more tests at PS/SPS (planned in June – November, 2004)
May 4, 2004
Photon Detector with PWO and APD / APS Meeting in Denver / Kenta Shigaki
12
- ALICE-PHOS Performance Evaluation 
sE/E = 1.3 %/E [GeV]  3.6 %/E [GeV]  1.1 % at – 25 C
May 4, 2004
Photon Detector with PWO and APD / APS Meeting in Denver / Kenta Shigaki
13
- Neutral Meson Measurement Capabilities 


hadron beams at 30 – 70 GeV/c
copper target of 6 cm thickness
invariant mass resolution sm/m = 7 % for p0, 3 % for h0
p0
h0
h0
May 4, 2004
Photon Detector with PWO and APD / APS Meeting in Denver / Kenta Shigaki
14
- Summary and Outlook 
high-granularity high-resolution electromagnetic calorimeter
• PbWO4 – scintillating crystal with smallest Moliere radius
• APD – compact and magnetic-field resistant readout


properties of key components investigated
several prototypes fabricated/tested in Japan/Europe
• energy resolution sE/E ~ 3 %/E [GeV]
• clear p0 and h0 peaks observed

first (out of 5) ALICE-PHOS module in 2005
• 5664 Russian PbWO4 crystals + Japanese APD readout system
• various R&D/design/production work in progress
• assembly/commissioning/tests planned in 2005

ALICE at LHC starting in 2007
May 4, 2004
Photon Detector with PWO and APD / APS Meeting in Denver / Kenta Shigaki
15
- ALICE-PHOS Collaboration 





CERN
China
Czech Republic
Germany
France
Japan
(Beijing, Wuhan, Wuhan)
(Prague)
(Münster)
(Nantes)
(Hiroshima)
R.Kohara, K.Hirashita, K.Homma, K.Shigaki, T.Sugitate, D.Toyoda,
Y.Tsuchimoto, K.Yokoyama



Norway
Poland
Russia
May 4, 2004
(Bergen, Oslo)
(Warsaw)
(Dubna, Moscow, Protovino, Sarov)
Photon Detector with PWO and APD / APS Meeting in Denver / Kenta Shigaki
16