Upload
others
View
2
Download
0
Embed Size (px)
Citation preview
Photomultiplier Tube Physics and Operation
Carlos Hernandez FahamBrown University
NEPPSR 2009
Carlos Hernandez Faham, Brown UniversityNEPPSR 2009 2
Afterpulsing!
Carlos Hernandez Faham, Brown UniversityNEPPSR 2009 3
“Photomultiplier tube? What is that?”
- Well-known dark matter theorist touring our lab
Carlos Hernandez Faham, Brown UniversityNEPPSR 2009 4
Photomultiplier TubePhotoelectric, Electron Multiplier
Carlos Hernandez Faham, Brown UniversityNEPPSR 2009 5
Biasing
-Vbias1 -Vbias2 -Vbias4 -Vbias6 -Vbias8 -Vbias10
-Vbias3 -Vbias5 -Vbias7 -Vbias9
Carlos Hernandez Faham, Brown UniversityNEPPSR 2009 6
Biasing
Signal
-Vbias
Carlos Hernandez Faham, Brown UniversityNEPPSR 2009 7
Biasing - Using a resistor chain base
Carlos Hernandez Faham, Brown UniversityNEPPSR 2009 8
Carlos Hernandez Faham, Brown UniversityNEPPSR 2009 9
How do you use a PMT
A
B
Carlos Hernandez Faham, Brown UniversityNEPPSR 2009 10
= 5
A
B
Single Photoelectron
Carlos Hernandez Faham, Brown UniversityNEPPSR 2009 11
Gain Calibration
LED
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
!!"" " !"" #"" $"" %"" &""
!""
!"!
!"#
!"$
!"%
!=
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
Carlos Hernandez Faham, Brown UniversityNEPPSR 2009 14
Carlos Hernandez Faham, Brown UniversityNEPPSR 2009 15
G ~ VK
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
Carlos Hernandez Faham, Brown UniversityNEPPSR 2009 17
Advantages:
High gain (single-photoelectron signals)Low-noise
Large detection areaFast response
Low radioactivity has been achieved
Carlos Hernandez Faham, Brown UniversityNEPPSR 2009 18
Carlos Hernandez Faham, Brown UniversityNEPPSR 2009 19
Dark Current
Thermionic emissionField emission
Afterpulsing (ion feedback)RadioactivityCosmic rays
!!"# ! !"# !"$ !"% !"& !"' !"( !")
!
#!!
$!!
*+,-./012
,3
!!"# ! !"# !"$ !"% !"& !"' !"( !")
!
#!!
$!!
*+,-./012
,3
Carlos Hernandez Faham, Brown UniversityNEPPSR 2009 20
K E
Ion feedback (“afterpulsing”)
photon
photon ion
0 0.5 1 1.5 2 2.5
0
20
40
60
80
100
120
140
Time (us)
mV
0 0.5 1 1.5 2 2.5
0
20
40
60
80
100
120
140
Time (us)
mV
Carlos Hernandez Faham, Brown UniversityNEPPSR 2009 21
0 0.5 1 1.5 2 2.5
0
20
40
60
80
100
120
140
Time (us)
mV
0 0.5 1 1.5 2 2.5
0
20
40
60
80
100
120
140
Time (us)
mV
0 0.5 1 1.5 2 2.5
0
20
40
60
80
100
120
140
Time (us)
mV
0 0.5 1 1.5 2 2.5
0
20
40
60
80
100
120
140
Time (us)
mV
0 0.5 1 1.5 2 2.5
0
20
40
60
80
100
120
140
Time (us)
mV
0 0.5 1 1.5 2 2.5
0
20
40
60
80
100
120
140
Time (us)
mV
sphe
0 0.5 1 1.5 2 2.5
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Time (us)
Carlos Hernandez Faham, Brown UniversityNEPPSR 2009 22
!!"# ! !"# !"$ !"% !"& ' '"# '"$ '"% '"&
!
!"(
'
'"(
#
#"(
)
*+,-./012
,3
45*-67081+9:.;<708=*+<91>.?4!#'@./'#!!32
.
.
A=*=
B=011+=9.C+*1
D;
4;'
4;#
4;)
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:
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
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
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
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
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...
Carlos Hernandez Faham, Brown UniversityNEPPSR 2009 29
Other PMT Imperfections
LinearityQECE
ResolutionAngular response
Magnetic Field Effects
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.)
Carlos Hernandez Faham, Brown UniversityNEPPSR 2009 31
Treat them well