r&d on fine-mesh multi-anode pmt with t.t.s.=100 ps under b 1t
DESCRIPTION
R&D on Fine-mesh multi-anode PMT with T.T.S.=100 ps under B 1T. Contents Introduction PMT structure & Set up Basic performance Experiment results Gain Time resolution Summary. T.Hokuue. Nagoya University, Japan. Multi-anode. Fine-mesh PMT. L24 - . - PowerPoint PPT PresentationTRANSCRIPT
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PID meeting @Nagoya Univ. 31.Aug.2002
Contents1. Introduction2. PMT structure & Set up3. Basic performance4. Experiment results
– Gain– Time resolution
5. Summary
R&D on Fine-mesh multi-anode PMT
with T.T.S.=100 ps under B1TT.HokuueNagoya University, Japan
Fine-mesh PMTL24 -
Multi-anode
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PID meeting @Nagoya Univ. 31.Aug.2002
IntroductionTOP counter : a new type of Cherenkov Ring Imaging detector
Single-photon sensitive with high efficiency Position sensitive : x 1 mm
Operate under magnetic field : B = 1.5T(at Belle )
Linear-array Multi-anode Fine-mesh PMT Nucl. Instrum. Meth. : A460,326-335,2001.
Hybrid Avalanche PhotoDiode (HAPD) Nucl. Instrum. Meth. : A463,220-226,2001.
Transit time spread : TTS = 100 ps
Our candidates
Requirements
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PID meeting @Nagoya Univ. 31.Aug.2002
A fine-mesh PMT exhibits a good position resolution and moderate time resolution for high multiple-photons, but not for single-photon.
We focused our effort to enhance the multiplication gain.
Under the magnetic field:
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PID meeting @Nagoya Univ. 31.Aug.2002
PMT structures
We made 3 different fine-mesh PMTs
Base: Multi-anode Fine-mesh PMT (R6135-L24X) made by Hamamatsu Photonics Company(HPK),Japan
• Common structure : - 24 anodes (readout
channels)- anode size 26.50.8 mm- # of stages of fine-mesh dynode 24 () or 19 ()
PMT Type
Distance L (mm)
H.V divider network ratio
Mesh Size (lines/inch),pitch
- 2.5-3 1:1: :1 2000 ,12.5m- 1 2:1: :1 2000 ,12.5m- 1 2:1: :1 2500 ,9m
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PID meeting @Nagoya Univ. 31.Aug.2002
1. Shorter distance between photo-cathode and first dynode2. H.V divider network ratio3. Finer mesh size
1. Shorter distance between photo-cathode and the first dynode
Transit time:
E1: the applied voltage across LL = 2.5-3 mm t 660 psL = 1 mm t 270 ps
L = 2.5-3 mmL = 1 mm
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PID meeting @Nagoya Univ. 31.Aug.2002
3. Finer mesh size
2. H.V divider network ratio
T.T.S. 100 ps (1: 1: 1:1) T.T.S. 70 ps (2: 2: 1:1)(ex.) Line-forcused PMT (R5900-L16)
1:1: … :1 2:1: … :1
2000 lines/inch (12.5m pitch) 2500 lines/inch (9m pitch)
The radius reduces with field strength.• The secondary electrons would
get to hit fewer dynodes
Using the finer mesh would undo this reduction somewhat!!
reduced multiplication gain
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PID meeting @Nagoya Univ. 31.Aug.2002
Set up• Set up
L24 -
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PID meeting @Nagoya Univ. 31.Aug.2002
Basic performance• Signal shape (-)
1. Single-photon sensitive
B = 0.4 T , H.V = 2400 V
The exhibits a quite clear single-photon peak.
Efficiency : 52 % (-)
• ADC distributions
Rise time 1ns
63 % (-)85% (-)
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PID meeting @Nagoya Univ. 31.Aug.2002
Basic performance2. Position sensitive
You can see clearly the field effect at weak field!!
- setting 1mm-wide slit on PMT’s surface• Anode-distributions(-
)• Signal spread in root-mean-square
The resolution of 0.5mm is dominated by the slit width of 1mm.True resolution might be much better than this.
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PID meeting @Nagoya Univ. 31.Aug.2002
Gain • Multiplication Gain • Relative gain
The : Gain 5 10 (B = 1.5T, H.V= 3400V)6
H.V = 1600 V
The exhibits less reduction and the highest gain at 0.2T.The : Gain 8 10 (B = 1.5 T, H.V= 2000 V)5
Gain/Gain(B=0T)
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PID meeting @Nagoya Univ. 31.Aug.2002
Time resolution• ADC-sliced time resolution (-,) & time-walk correction
0.4T,1.5kV 0.6T,1.7kV 1.0T,2.2kV
T.T.S 150 ps at ADC = 175-th ch at
T.T.S 100 ps at B 1T
0.4T,2.4kV
T.T.S 100 ps at ADC = 180-190 ch
-
-
150 ps at B = 1.5T
type
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PID meeting @Nagoya Univ. 31.Aug.2002
• Gain vs. T.T.S.
Increment of gain by factor of 10
has rather steeper relation than
improve T.T.S of
30 ps (-)45 ps (-)
The time resolution under various conditions are plotted for and PMTs.
Both PMTs indicate that the multiplication gain of 3-5 10 are required to have a time resolution of 100ps.
7
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PID meeting @Nagoya Univ. 31.Aug.2002
• Multi-photons2-photons TTS 80 ps3-photons TTS 70 ps4-photons TTS 60 ps
• T.T.S. with Multi-photons (-)
We already obtained high time resolution for multiple-photons.
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PID meeting @Nagoya Univ. 31.Aug.2002
- By developing fine-mesh 24-anodes PMT
Summary
Time resolution : 100 ps (B1T)150 ps (B=1.5T)
- To have a 100 ps resolution under B=1.5T multiplication gain of
3-5 10 is required 7
- For higher gain and better T.T.S.
by using finer mesh dynodes by increasingly applied H.V. on the first dynode
- For Multiple-photons …
by reducing distance between the first dynode and photo-cathode