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International Symposium on the Development of Detectors, 2006/4 at SLAC
Time of Flight measurementswith MCP-PMT
- Very high resolution TOF counter- Lifetime of MCP-PMTs
T.Ohshima, K.Inami, N.Kishimoto, M.Nagamine(Nagoya university, Japan)
2006/4/3-6 SNIC at SLAC 2
Introduction
~400mm
Linear-array type photon detector
LX
20mm
Quartz radiatorx
y
z
Photon device for TOP counterCherenkov ring imaging counter with precise time measurement (NIM A 440 (2000) 124)
For super B-factory
Single photon sensitivityGood transit time resolution (<50ps)Operational under 1.5T B-fieldPosition sensitive (~5mm)High detection efficiency
MCP-PMT is a good solution.In the course of R&D,
Idea of a few psec resolution TOF
MCP-PMT for TOP counter
2006/4/3-6 SNIC at SLAC 3
0
200
400
600
0 0.1 0.2 0.3 0.4
Arb
itrar
y sc
ale
0
10
20
30
40
Arb
itrar
y sc
ale
0 2 4 6Emission and propagation time (ns)
StructureSmall-size quartz (cm~mm length)
Cherenkov light (Decay time ~ 0) extremely reduce time dispersion compared to scintillation (τ ~ ns)
MCP-PMT (multi-alkali photo-cathode)TTS < 50ps even for single photongives enough time resolution for smaller number of detectable photons
Cherenkov light
Scintillation (BC408)Test counter
Simulation
Nγ~240
Nγ~820
High resolution TOF
2006/4/3-6 SNIC at SLAC 4
MCP-PMTMicro-Channel-Plate
Tiny electron multipliersDiameter ~10µm, length ~400µm
High gain~106 for two-stage type
→ Fast time responsePulse raise time ~500ps, TTS < 50ps
can operate under high magnetic field (~1T)
Photo-cathode MCP plates Anode
Photon
Single photonChannel
~400µm
φ~10µmInput electron
HV
MCP channel
2006/4/3-6 SNIC at SLAC 5
MCP-PMT (2)
Window size : 25mmφ
R3809U-50-25X
ADC (count/0.25pC)
0
200
400
600
100 120 140N
um
be
r o
f E
ve
nts
TDC (count/25psec)
0
500
1000
1500
-20
Nu
mb
er
of
Ev
en
ts
200
σ=46psfor single photon
single photon peak
0
200
400
600
800
1000
1200
100 110 120 130ADC (1bin/0.25pC)
even
t
0
200
400
600
800
1000
-20 -10 0 10 20
30.4psec
TDC(25ps/count)
even
t
Hamamatsu R3809U-50 (multi-alkali photo-cathode)
R3809U-50-11X
Window : 11mmφ
MCP hole 10µmφ
MCP hole 6µmφ
Gain ~ 106
2006/4/3-6 SNIC at SLAC 6
Beam test 13GeV/c π− beam
at KEK-PS π2 linePMT: R3809U-50-25XQuartz radiator
16x16x40mm with Al evaporation
TOF between two countersevaluate the time resolution
TOF counter with and without quartz radiator
To confirm MCP-PMT’s behavior for passage of charged particles
Test counter
Beam
Trigger counter
Trigger counter
Tile TOF counter
Quartz
MCP PMT
z
x
5 x5 x10 mm Scinti. BC408x y z
16 x16 x40 mmx y z
HPK R3809U-50-25XPhoto-Cathode φ25mmsingle-photon TTS 50psec
40mm
60cm
2006/4/3-6 SNIC at SLAC 7
Beam test 1 resultWith quartz radiator
Number of photons ~ 250agree with expectation of simulation ~240
Time resolution ~ 10.6ps
Without radiatorNumber of photons ~ 50
Cherenkov light from PMT windowTime resolution ~ 13.6ps
Resolution is limited by readout electronics. (σelec~8.8ps)
Expected intrinsic resolution ~5.9pstof (ps)
0 25 50-25-50
0 25 50-25-50tof (ps)
with radiator
without radiator
2006/4/3-6 SNIC at SLAC 8
Beam test 2Confirmation of intrinsic time resolution
ImprovementsReadout electronics
σelec.: 8.8ps 4psTime-correlated Single Photon Counting Modules (SPC-134, Becker & Hickl GMbH’s)
CFD, TAC and ADC Channel width = 813fsElectrical time resolution = 4ps RMS
MCP-PMTTTS: ~46ps ~30ps10µm hole 6µm hole
R3809U-50-25X -11X
2006/4/3-6 SNIC at SLAC 9
Beam test 2 setup3GeV/c π− beam
at KEK-PS π2 linePMT: R3809U-50-11XQuartz radiator
10φx40zmm with Al evaporation
0
100
200
300
40 80 120
4.1ps
Even
tsTDC (ch/0.814ps)
Elec. resolutionBeamTrig.1
Trig.2TOF1 TOF2
30cm
Trig.1 Coinc. Discri.Divider
Trig.2
TOF2
TOF1PowerSpliter
Discri.
Discri.Divider
Start Stop
π, 3GeV/c-
SPC-134
2006/4/3-6 SNIC at SLAC 11
Beam test 2 resultWith 10mm quartz radiator
+3mm quartz windowNumber of photons ~ 180Time resolution = 6.2psIntrinsic resolution ~ 4.7ps
Without quartz radiator3mm quartz windowNumber of photons ~ 80
Expectation ~ 20 photo-electrons
Time resolution = 7.7ps
Even
ts
100
200
300
400
40 80 120 1400TDC (ch/0.814ps)
6.2ps
100
200
300
40 80 120 1400
TDC
7.7ps
(ch/0.814ps)Ev
ents
2006/4/3-6 SNIC at SLAC 12
Beam test 2 result (cont’d)Nγ, σTOF v.s. radiator thickness
Extra photo-electronsNp.e. from short distance is larger than that of expected.
Time-resolution behaviorResolution is gradually worse.
Extra p.e. would affect the resolution dependence.
2
4
6
8
10
12
14
Beam-test Simulation
100
200
300
Quartz thickness (mm)0 20 4010 30 500 20 4010 30 50
Quartz thickness (mm)σ
(ps)
TOF
Np.
e.
Counter-1
SimulationCounter-2
2006/4/3-6 SNIC at SLAC 13
LifetimeHow long can we use MCP-PMT under high hit rate?
Light load by LED pulse (1~5kHz)20~100 p.e. /pulse (monitored by normal PMT)
HPK (x2) Russian (x5)Al protection O X O X
65% 55-60%Correction eff. 37% 40-60%Effective area 11mmφ 18mmφ
Gain 1.9x106 1.5x106 3-4x106
29ps 30-40ps
Bias angle 13deg 5deg
TTS 34psPhoto-cathode Multi-alkali (NaKSbCs)Quantum eff. at 400nm 21% 19% 16-20%
2006/4/3-6 SNIC at SLAC 14
Gain & TTS for single photonGain TTS
Russian w/o Al (#6)
HPK w/o Al
Russian w/ Al(#32)
HPK w/ Al
-before-after
σ=31psσ=36ps
σ=43psσ=32ps
σ=34psσ=34ps
σ=29psσ=33ps
0
0.2
0.4
0.6
0.8
1
1.2
0 200 400 600 800 1000 1200Output charge (mC/cm2)
Rel
ativ
e ga
in
HPK w/ AlHPK w/o Al
Russian w/ Al (#32)Russian w/ Al (#35)Russian w/ Al (#38)Russian w/o Al (#6)Russian w/o Al (#11)
TTS is stable within the gain drops.
~1012 p.e./cm2
with 106 gain
2006/4/3-6 SNIC at SLAC 15
Quantum efficiencyQ.E. Before/After
λ=400nm
0
0.2
0.4
0.6
0.8
1
1.2
0 200 400 600 800 1000 1200
Rel
ativ
e Q
.E.
Output charge (mC/cm2)
10-3
10-2
10-1
1
200 300 400 500 600 700 800 900λ(nm)
Q.E
. rat
io
HPK w/ AlHPK w/o Al
Russian w/ Al (#32)Russian w/ Al (#35)Russian w/ Al (#38)Russian w/o Al (#6)Russian w/o Al (#11)
• Small Q.E. drop for HPK with protection• Fast degradation for longer wavelength
~1012 p.e./cm2
with 106 gain
2006/4/3-6 SNIC at SLAC 16
SummaryHigh resolution TOF counter
Small quartz as Cherenkov radiator MCP-PMT (TTS ~30ps for single photon)Readout system (time resolution ~4ps)Time resolution of 6.2ps have been measured.
4.7ps intrinsic resolution
Lifetime test of MCP-PMTsAl protection layer works well to stop feedback ions.MCP-PMT by HPK with Al layer is best solution.
For more detail, please refer NIM A 528, 763 (2004) and new paper to be published in NIM A.
2006/4/3-6 SNIC at SLAC 17
Separation power
1
10
0 2 4 6Momentum (GeV)
Sep
arat
ion
3
σ=100psecσ=50psecσ=20psecσ=10psecσ=5psec
L=1.0m
2006/4/3-6 SNIC at SLAC 18
Fluctuation of Readout elec.8 TDC channels with logic pulse
0
2
4
6
8
10
12
14
16
8Number of used channel
RM
S(p
sec)
2 4 60
■ 8.8psecpsec8.8=moduleσ ch#
8.8
Diveder
CAMAC
ADC
TDC
Discri.
Gate
Clock Generator Discri.
8
1
2
startstop
startstop
startstop
ttT
ttT
ttT
−=
−=
−=
8
2
1
8
2
1
2)()(
2)43()21( 4321 stopstopstopstop ttttTTTT +−+
=+−+
22/)21(
22
2121
TTstop
stopstopTT
−
−
≅
+=
σσ
σσσ
42/)4321( TTTT
stop−−+≅
σσ
2121 stopstop ttTT −=−
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