Latest developments in PMTs for low temperature operation

Latest developments in PMTs
for low temperature operation
DM2014 on February 28, 2014
Yuji Hotta
Electron Tube Division
Hamamatsu Photonics K.K.
Contents
1. PMT Lineup for Low Temperature Operation
2. Countermeasures against Light Emission
3. Developmental Status for 4 inch Metal Bulb PMT
1. PMT Lineup for Low
Temperature Operation
PMTs for Low Temperature Operation
R8778
(2 inch round)
R11410
R11065
(3 inch round)
R8520-406
R8520-506
(1 inch square)
R6041-406
R6041-506
(2 inch round)
PMT for Low Temperature Operation
Items
R8520-406
R8520-506
R8778
R6041-406
R6041-506
R11410
R11065
Size / Shape
1 inch square
2 inch round
2 inch round
3 inch round
Outer Size
25.7 mm sq.
57 mm dia.
57 mm dia.
76 mm dia.
Min. Effective Area
20.5 mm sq.
45 mm dia.
45 mm dia.
64 mm dia.
Tube Length
28.3 mm
111.5 mm
32.5 mm
123 mm
QE
30%
at 175 nm
25%
at 420 nm
26%
at 175 nm
30%
at 175 nm
25%
at 420 nm
26%
at 175 nm
25%
at 420 nm
Min. Operating Temp.
-110 deg. C
-186 deg. C
-110 deg. C
-110 deg. C
-186 deg. C
-110 deg. C
-186 deg. C
Dynode Structure
Metal Channel
Box & Line
Metal Channel
Box & Line
Number of Dy Stages
10
12
12
12
Supply Voltage
800 V
1500 V
800 V
1500 V
Gain
1E+06
5E+06
1E+06
5E+06
Rise Time
1.8 ns
5 ns
2.3 ns
5.5 ns
Pulse Linearity
at +/-2% deviation
30 mA
13 mA
40 mA
20 mA
Radioactivity
10 mBq/PMT
70-100 mBq/PMT
150 mBq/PMT
70-100 mBq/PMT
R11410 & R11065 Quantum Efficiency
175 nm
26% typ.
30% min.
420 nm
25% typ.
30% min.
R11410/R11065 Series
Glass Stem
Kovar
Leads
Ceramic Stem
Ceramic
Insulator
Quartz
Insulator
Estimated RI
16 mBq/PMT
Estimated RI
75 mBq/PMT
40K
U
Th 60Co Total
40K
U
7
6
1
50
20
(mBq/PMT)
2
16
R11410-10
R11065-10
R11410
R11065
Th 60Co Total
3
2
75
(mBq/PMT)
R11410/R11065 Series
Aluminum
Sealing
Kovar
Metal
Co free
Metal
d = 1.0 mm
d = 2.3 mm
High-Purity
Aluminum
R11410-20 / R11065-20 (Cobalt free metal type) is now available.
Kovar metal contains 60Co, its RI is about 2 mBq/PMT.
Cobalt free metal can reduce it to 0.4 mBq/PMT.
8
2. Countermeasures against
Light Emission
Light Emission
Last year, we were informed from a customer that R11065-20 might
emit light at liquid argon temperature.
As a result of our checking, we confirmed light emission in R11065-20.
Top View
FLANGE
Bottom View
STEM
Light Emission / Countermeasure
Possible Cause of Light Emission
(1) Voltage tolerance of ceramic
Reduce supply voltage between pins
Enlarge distance between pins
(2) Electron charge up on ceramic stem
Put metal plate or quartz plate on ceramic stem
Use metal stem
Light Emission / Countermeasure
Disk
The maximum voltage gap between
Pin#11 and Pin#12 is more than 1000V.
Original Type
Current Type
1176V
Getter
1419V
K
0V
Max. Voltage Gap
1176 V (Pin#11 - #12)
at 1500 V (K-P)
Dy10 Dy6
Dy8
Dy2
Dy4
G
Light Emission / Countermeasure
The maximum voltage gap is reduced
to 324 V from 1176 V.
Modified Type
Modified Type
Getter
324 V
0V 324 V
Max. Voltage Gap
324 V (Pin#17 - #18)
324 V (Pin#1 – #20)
at 1500 V (K-P)
K
Pin#20
Pin#18
Dy4
Dy2
G
Output Monitor for Modified type (at -1750V)
Condition: 5uA output, -1750V, at -196C(Liq.N2)
Tube Type Serial Number
R11065-20
R11065-20
R11065-20
ZK6853
ZK6854
ZK6855
Output Stability
(in Liq.N2)
Stable
Stable
Unstable
Two of three tubes showed stable
output for 2 hours at -1750V.
Modified type shows some effect, but
it could be not perfect solution.
ZK6854
ZK6853
Stable output for
2 hours operation
This result was informed during Capri meeting.
ZK6855
Stable output for
2 hours operation
Light emission
after 30 minutes
Countermeasure / Fillet
It could be necessary to modify the shape of Ceramic Stem so that the
distance between pins can be enlarged.
Current Type
Ceramic Plate
Metalizing
Current Type
Kovar Pin
Fillet Type
Ceramic
Fillet
Fillet Type
Fillet
Countermeasure / Metal Plate & Stem
We guess that electron charge-up could be a trigger for light emission.
Metal Plate
Metal
Plate
Nippers
as a stand
Metal plate is connected to K.
Metal plate is floating against
the ceramic plate.
Metal
Stem
<Side View>
<Bottom View>
Countermeasure / Quartz Plate
The other idea to prevent charge-up of electrons is to place a quartz plate
on the ceramic stem.
NC (Pin#10)
Stopper
Ceramic Stem
Quartz Plate with bore
NC
(Pin#19)
holes (transparence)
K (Pin#20)
We made 7 trial tubes. All the tubes showed stable
output over 7 hours in liquid nitrogen.
3. Developmental Status for
4 inch Metal Bulb PMT
4-inch Metal Bulb PMT Development
Tube Length: 130 mm
400 nm
99.0%
175 nm
3.3 ns (FWHM)
B/L 12 stages
Diameter: 104 mm
Effective Area: 91 mm
Simulated values
90.5%
4.3 ns (FWHM)
4-inch Development / Trial for sealing
Quartz Faceplate
Aluminum
Sealing
Attachment of Kovar Flange to
Quartz Faceplate was completed.
Aluminum Ring
Kovar Flange
(It consists of 2 parts.)
4-inch Development / He Leak test
Quartz faceplate with Kovar flange
is placed on the stage.
He gas is applied at the edge
of Kovar flange by spray gun.
Leak Tester
He Gas Cylinder
< Helium Leak Test System >
He peak is not appeared.
4-inch Development / First trial
3 inch PMT
4 inch PMT
<Top View>
4 inch PMT
3 inch PMT
<Side View>
4-inch Development / First trial
4 inch Metal Bulb PMT Quantum Efficiency
Quantum Efficiency [ % ]
35
28.1% at 420 nm
30
25
20
15
10
5
0
150
Gain : 6.3E+06 at 1500 V
Idb : 4.6 nA at 1500 V
200
250
300
350
400
450
Wavelength
500
550
[ nm ]
600
650
700
750
Summary
- We are trying to solve the light
emission problem. It seems that
quartz plate type would be effective
to prevent light emission at liquid
argon temperature.
- We are developing 4 inch metal bulb
PMT for low temperature operation.
The development has gone well so far.

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