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Photomultiplier Tube Physics and Operation
Carlos Hernandez FahamBrown University
NEPPSR 2009
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Carlos Hernandez Faham, Brown UniversityNEPPSR 2009 2
Afterpulsing!
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Carlos Hernandez Faham, Brown UniversityNEPPSR 2009 3
“Photomultiplier tube? What is that?”
- Well-known dark matter theorist touring our lab
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Carlos Hernandez Faham, Brown UniversityNEPPSR 2009 4
Photomultiplier TubePhotoelectric, Electron Multiplier
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Carlos Hernandez Faham, Brown UniversityNEPPSR 2009 5
Biasing
-Vbias1 -Vbias2 -Vbias4 -Vbias6 -Vbias8 -Vbias10
-Vbias3 -Vbias5 -Vbias7 -Vbias9
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Carlos Hernandez Faham, Brown UniversityNEPPSR 2009 6
Biasing
Signal
-Vbias
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Carlos Hernandez Faham, Brown UniversityNEPPSR 2009 7
Biasing - Using a resistor chain base
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Carlos Hernandez Faham, Brown UniversityNEPPSR 2009 8
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Carlos Hernandez Faham, Brown UniversityNEPPSR 2009 9
How do you use a PMT
A
B
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Carlos Hernandez Faham, Brown UniversityNEPPSR 2009 10
= 5
A
B
Single Photoelectron
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Carlos Hernandez Faham, Brown UniversityNEPPSR 2009 11
Gain Calibration
LED
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Carlos Hernandez Faham, Brown UniversityNEPPSR 2009 12
Gain Calibration
!
P(n;µ) =µne"µ
n!
!
P(2) = 0.1" P(1)
!
µ2e"µ
2= µe"µ
# µ = 0.2
!
P(0) = e"0.2
= 0.82
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!!"" " !"" #"" $"" %"" &""
!""
!"!
!"#
!"$
!"%
!=
6.4 µ = 140.8 mVnsGain = 3.5e+07 ± 4.1e+05Res = 0.289
'()*+,-./01
234/50
678+2*9:;(*5:3/+<3(+=>?+@'"#!&+*5+!&""+.
Carlos Hernandez Faham, Brown UniversityNEPPSR 2009 13
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Carlos Hernandez Faham, Brown UniversityNEPPSR 2009 14
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Carlos Hernandez Faham, Brown UniversityNEPPSR 2009 15
G ~ VK
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Carlos Hernandez Faham, Brown UniversityNEPPSR 2009 16
! "!! #!! $!! %!! &!!! &"!! &#!! &$!! &%!! "!!!
&!&
&!"
&!'
&!#
(&)*+,-.
/01234
/0!56)(&)72-89:)(+-;381<
)
)
=>3>
?>144@>2)A@3B
)))!)C)5$DE5)F-G--
)))!)C)D#ED)F-G--
)))H@9,3)I@-JK)C)#E6)+,-LF-G--)))M-40J13@02)C)&$E6N
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Carlos Hernandez Faham, Brown UniversityNEPPSR 2009 17
Advantages:
High gain (single-photoelectron signals)Low-noise
Large detection areaFast response
Low radioactivity has been achieved
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Carlos Hernandez Faham, Brown UniversityNEPPSR 2009 18
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Carlos Hernandez Faham, Brown UniversityNEPPSR 2009 19
Dark Current
Thermionic emissionField emission
Afterpulsing (ion feedback)RadioactivityCosmic rays
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!!"# ! !"# !"$ !"% !"& !"' !"( !")
!
#!!
$!!
*+,-./012
,3
!!"# ! !"# !"$ !"% !"& !"' !"( !")
!
#!!
$!!
*+,-./012
,3
Carlos Hernandez Faham, Brown UniversityNEPPSR 2009 20
K E
Ion feedback (“afterpulsing”)
photon
photon ion
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0 0.5 1 1.5 2 2.5
0
20
40
60
80
100
120
140
Time (us)
mV
0 0.5 1 1.5 2 2.5
0
20
40
60
80
100
120
140
Time (us)
mV
Carlos Hernandez Faham, Brown UniversityNEPPSR 2009 21
0 0.5 1 1.5 2 2.5
0
20
40
60
80
100
120
140
Time (us)
mV
0 0.5 1 1.5 2 2.5
0
20
40
60
80
100
120
140
Time (us)
mV
0 0.5 1 1.5 2 2.5
0
20
40
60
80
100
120
140
Time (us)
mV
0 0.5 1 1.5 2 2.5
0
20
40
60
80
100
120
140
Time (us)
mV
0 0.5 1 1.5 2 2.5
0
20
40
60
80
100
120
140
Time (us)
mV
0 0.5 1 1.5 2 2.5
0
20
40
60
80
100
120
140
Time (us)
mV
sphe
0 0.5 1 1.5 2 2.5
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Time (us)
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Carlos Hernandez Faham, Brown UniversityNEPPSR 2009 22
!!"# ! !"# !"$ !"% !"& ' '"# '"$ '"% '"&
!
!"(
'
'"(
#
#"(
)
*+,-./012
,3
45*-67081+9:.;<708=*+<91>.?4!#'@./'#!!32
.
.
A=*=
B=011+=9.C+*1
D;
4;'
4;#
4;)
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Carlos Hernandez Faham, Brown UniversityNEPPSR 2009 23
0.025 0.026 0.027 0.028 0.029 0.03 0.031 0.0320
0.5
1
1.5Afterpulsing Delay vs. Bias Voltage, BA0217, Main Pulse ~100 pC (Anode)
1/!
(bias) [V]
Aft
erpu
lsin
gD
elay
![µ
s]
Charge/Mass Ratio:
AP1 = 1.1 ± 0.6
AP2 = 4.00
AP3 = 15.2 ± 0.1
AP1
AP2
AP3
AP1
AP2
AP3
Tip from Hamamatsu: For the R8778, He+ is at ~ 0.5 µs
Mass-to-charge ratio:
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Carlos Hernandez Faham, Brown UniversityNEPPSR 2009 24
!!"# ! !"# !"$ !"% !"& ' '"# '"$ '"% '"&
!
!"(
'
'"(
#
#"(
)
*+,-./012
,3
45*-67081+9:.;<708=*+<91>.?4!#'@./'#!!32
.
.
A=*=
B=011+=9.C+*1
D;
He+
H+N+, O+ ...& He+ reflections
< 15% from coincidence study.Ignore it for practical purposes
![Page 25: Brown University NEPPSR 2009 - Home | Boston University ...physics.bu.edu/neppsr/TALKS-2009/Faham_PMToperation.pdf · NEPPSR 2009 Carlos Hernandez Faham, Brown University 4 Photomultiplier](https://reader033.vdocuments.net/reader033/viewer/2022043005/5f8d6bae14beed7d6a42d62d/html5/thumbnails/25.jpg)
0 10 2010
0
101
# phe AP1
Counts
/ b
in
AP1
Data
Gaussian Fit
Mean = 8.3 ± 0.4 phe
Sigma = 1.9 phe
0 10 20 3010
0
101
102
103
104
# phe AP2
Counts
/ b
in
AP2
Data
Gaussian Fit
Mean = 5.6 ± 0.1 phe
Sigma = 2.9 phe
Mean # phe ejected from photocathode per afterpulse, BA0217 (1200 V)
0 5 10 1510
0
101
102
# phe AP3
Counts
/ b
in
AP3
Data
Gaussian Fit
Mean = 4.2 ± 0.2 phe
Sigma = 2.4 phe
Carlos Hernandez Faham, Brown UniversityNEPPSR 2009 25
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5 10 20 35 50 75 1002
4
6
8
10
15
Main Pulse (# phe)
Aft
erp
uls
e (
# p
he
)
Afterpulsing charge vs. Main pulse charge, BA0217, Bias = 1200 V
AP1
AP2
AP3
Carlos Hernandez Faham, Brown UniversityNEPPSR 2009 26
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Carlos Hernandez Faham, Brown UniversityNEPPSR 2009 27
0 0.5 1 1.5 2 2.5
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
0.18
0.2
Afterpulsing ratio for BA0400 (average of 3001 pulses)(Bias = 1500 V)
Time (us)
Afterpulsing Ratio (APR) = 1.0%
Main pulse 84 pC (10.4 phe)Afterpulses1 pC (0.1 phe)
Cumulative APR
This is a healthy PMT
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0 0.5 1 1.5 2 2.5
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
0.18
0.2
Afterpulsing ratio for BA0211 (average of 3001 pulses)(Bias = 1500 V)
Time (us)
H+
He
++, H
2+
He
+
N+,O
+
H2O
N2+,O
2+
Ar+
N+,O
+ R
eflection
Ne
+
C D E F
O2+
BA
Carlos Hernandez Faham, Brown UniversityNEPPSR 2009 28
This is your PMT on drugs...
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Carlos Hernandez Faham, Brown UniversityNEPPSR 2009 29
Other PMT Imperfections
LinearityQECE
ResolutionAngular response
Magnetic Field Effects
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Carlos Hernandez Faham, Brown UniversityNEPPSR 2009 30
Concluding Remarks
Effective photo-detection devices
Widely used
Many advantages: high gain, low noise, fast response, etc.
Some disadvantages that we have to be aware of(dark current, AP, non-linearity, low QE, etc.)
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Carlos Hernandez Faham, Brown UniversityNEPPSR 2009 31
Treat them well