Photomultipliers:Uniformity measurements
L. Pereira1, A. Morozov1, M. M. Fraga1, L. M. S. Margato1, P. Assis2, R. Conceição2, F. A. F. Fraga1
1 LIP - Coimbra
2 LIP - Lisboa
IDPASC School on Digital Counting Photosensors for Extreme Low Light Levels, Lisbon 16 - 21 May 2010
L . Pereira 2
Photomultiplier tubes
Outline
The discovery of the cosmic radiation
Air fluorescence in the context of the cosmic radiation detection
Uniformity of the Auger FD PMTs
Position sensitive micropattern gaseous neutron detector with optical readout
Simulations with ANTS: Anger-camera Neutron detector Toolkit for Simulation
IDPASC School on Digital Counting Photosensors for Extreme Low Light Levels, Lisbon 16 - 21 May 2010
L . Pereira 3
Photomultiplier Tubes (PMT)
Good
High gain: up to 107
Low dark count
Fast response time: RT&FT<1ns
Large sensitive areas
Bad
Bulky
Unstable
Sensitive to magnetic fields
High voltage
IDPASC School on Digital Counting Photosensors for Extreme Low Light Levels, Lisbon 16 - 21 May 2010
L . Pereira 4
Radiant Sensitivity and Quantum Efficiency
IDPASC School on Digital Counting Photosensors for Extreme Low Light Levels, Lisbon 16 - 21 May 2010
L . Pereira 5
Between 1911 and 1912 Viktor Hess climbed into a balloon up to altitudes higher as 5000 m, and proved that there was a penetrating radiation that crossed the atmosphere and increased with altitude.
He gave this phenomenon the name "Cosmic Radiation",which later evolved to "Cosmic Rays".
The discovery of cosmic rays
For some time it was believed that Earth was the only source of natural radiation.
Hess received the Nobel prize in 1936 for the discovery of the cosmic rays.
IDPASC School on Digital Counting Photosensors for Extreme Low Light Levels, Lisbon 16 - 21 May 2010
L . Pereira 6
~ 12 Km~ 210 K
Years later in 1938, Pierre Auger discovered that cosmic rays interact with the atmosphere creating a particle shower.
He estimated that the primary particles (i.e. the particles that create the shower) should be very energetic (1015 eV).
IDPASC School on Digital Counting Photosensors for Extreme Low Light Levels, Lisbon 16 - 21 May 2010
L . Pereira 7
The particle shower is accompanied with the emission of light due to the interaction with the air molecules.
Almost all light is emitted between 300 and 400 nm, and is produced during the de-excitation of the nitrogen molecules.
The scintillation light yield is proportional to the energy of the cosmic ray.
Which means that…
If we are able to measure the amount of light during an air shower we can determined the energy of the cosmic: Fluorescence Telescopes.
IDPASC School on Digital Counting Photosensors for Extreme Low Light Levels, Lisbon 16 - 21 May 2010
L . Pereira 8
The first attempts to observe the extensive air showers
through the observation of the scintillation date from the
60’s, in the University of Cornell (USA). The research group
included the Post-Graduated student Alan Bunner, who’s
PhD thesis became a reference.
Bunner, A. N., Cosmic Ray Detection by Atmospheric Fluorescence,
Ph. D. Thesis, Cornell University (1967).
IDPASC School on Digital Counting Photosensors for Extreme Low Light Levels, Lisbon 16 - 21 May 2010
L . Pereira 9
Fluorescence detector camera: 440 PMT
Pierre Auger Observatory
Photonis XP3062
Hexagonal bi-alkali 8 stage
IDPASC School on Digital Counting Photosensors for Extreme Low Light Levels, Lisbon 16 - 21 May 2010
L . Pereira 10
PMT Uniformity
Variation of the anodic signal
along the photocathode’s surface
IDPASC School on Digital Counting Photosensors for Extreme Low Light Levels, Lisbon 16 - 21 May 2010
L . Pereira 11
Area dependence of the anode sensitivity: Experimental system
LEDs: 340 ± 15 nm, 370 nm ± 10 nm and 395 nm ± 15 nm …
XY table, ~ 25 μm resolution
Bursts of several 200 ns width pulses per position
Multistage collimator, 1 mm holes, 1 mm FWHM beam profile
PCPULSER
LED
COLLIMATOR
PMT
MOTOR DRIVEN XY TABLE
X
Y
DIGITAL OSCILLOSCOPE
PMT SIGNAL
X
Y
TRIGGER
The read out linearity was checked for the whole dynamic range using neutral density filters
IDPASC School on Digital Counting Photosensors for Extreme Low Light Levels, Lisbon 16 - 21 May 2010
L . Pereira 12
IDPASC School on Digital Counting Photosensors for Extreme Low Light Levels, Lisbon 16 - 21 May 2010
L . Pereira 13
IDPASC School on Digital Counting Photosensors for Extreme Low Light Levels, Lisbon 16 - 21 May 2010
L . Pereira 14
Photonis XP5602
Round Ø effective = 56 mm bi-alkali 8 stage
However for an Gama Camera grade PMT…
IDPASC School on Digital Counting Photosensors for Extreme Low Light Levels, Lisbon 16 - 21 May 2010
L . Pereira 15
IDPASC School on Digital Counting Photosensors for Extreme Low Light Levels, Lisbon 16 - 21 May 2010
L . Pereira 16
The Anger Camera
In 1957 Hal Anger invented the scintillation camera known also as the gamma camera or Anger camera
Technetium (99mTc) sestamibi upper body scan for thyroid evaluation.
IDPASC School on Digital Counting Photosensors for Extreme Low Light Levels, Lisbon 16 - 21 May 2010
L . Pereira 17
An Anger type optical readout, micropattern gaseous neutron detector
Cross section: 5330 barns
PC + Position reconstruction algorithm → [X, Y]
200 300 400 500 600 700 800 900
10-2
10-1
100
101
WAVELENGTH (nm)
QU
AN
TU
M E
FF
ICIE
NC
Y (
%)
200 300 400 500 600 700 800 9000
0.5
1
1.5
2x 10
-4
INT
EN
SIT
Y
CF4 SpectrumCF4 Weighted Spectrum
Q.E.
IDPASC School on Digital Counting Photosensors for Extreme Low Light Levels, Lisbon 16 - 21 May 2010
L . Pereira 18
Avalanche light
3 bar CF4
V Anode - Cathode = 1.85 kV
I ~ 80 nA
ZoomedNo zoom
The irradiated area spanned ~16 anodes
Microstrip: IMT, Masken und Teileungen AG SN: 850771396Pitch = 1 mmAnode width = 10 μmCathode width = 600 μm
IDPASC School on Digital Counting Photosensors for Extreme Low Light Levels, Lisbon 16 - 21 May 2010
L . Pereira 19
Cathode radiant sensitivity and quantum efficiency of theHamamatsu R5070A as a function of the wavelength of the incident light
Hamamatsu R5070A
Multialkalli photocathode
Q.E. : ~10% at 300 nm maximum of ~20% at 420 nm ~2% at 800 nm
General caracteristics
Prismatic borosilicate windowSquare pyramids 1 x 1 mm2 base,45º half angle
200 300 400 500 600 700 800 900
1
1020
QU
AN
TU
M E
FF
ICIE
NC
Y (
%)
200 300 400 500 600 700 800 9000
0.5
1
1.5
2
INT
EN
SIT
Y (
a. u
.)
Ordered by ILL to the large scale prototype
Ø 25 mm
IDPASC School on Digital Counting Photosensors for Extreme Low Light Levels, Lisbon 16 - 21 May 2010
L . Pereira 20
X-Axis (mm)
Y-A
xis
(mm
)
25 30 35 40 45 5025
30
35
40
45
50
55
20 30 40 50 600
20
40
60
80
100X=38 mm
Y-Axis (mm)
Rel
ativ
e O
utpu
t (%
)
20 30 40 50 600
20
40
60
80
100Y=40 mm
X-Axis (mm)
Rel
ativ
e O
utpu
t (%
)
3040
50
3040
50
0
50
100
X-Axis (mm)Y-Axis (mm)
Rel
ativ
e O
utpu
t (%
)
20
40
60
80
100
SN6203, 1Kv, 395nm, 0degrees
~30 %
SN 6203, λ = 395 nm
IDPASC School on Digital Counting Photosensors for Extreme Low Light Levels, Lisbon 16 - 21 May 2010
L . Pereira 21
PMT-to-PMT variation for the same model
0 10 20 300
10
20
30
X (mm)
Y (
mm
)
SN: 6289, = 395 nm, step = 1 mm
0 10 20 300
10
20
30
X (mm)
Y (
mm
)
SN: 6279, = 395 nm, step = 1 mm
0 10 20 300
10
20
30
X (mm)
Y (
mm
)
SN: 6299, = 395 nm, step = 1 mm
10
20
30
40
50
60
70
80
90
100
0 10 20 300
10
20
30
X (mm)
Y (
mm
)
SN: 6291, = 395 nm, step = 1 mm
10
20
30
40
50
60
70
80
90
100
IDPASC School on Digital Counting Photosensors for Extreme Low Light Levels, Lisbon 16 - 21 May 2010
L . Pereira 22
25 30 35 40 45 50 550
10
20
30
40
50
60
70
80
90
100
X (mm)
Rel
ativ
e ou
tput
(%
)
SN6203, 1kV, 395nm, HighRes 0.1 mm
27 31 35 39 43 47 51 5535
37
39
X (mm)
SN6203, 1kV, 395nm, Step = 0.1 mm
Y (
mm
)
75
80
85
90
95
Relative anode sensitivity of an 18 × 4 mm2 area scanned with a 0.1 mm step.
Sensitivity varies according the prismatic structure pitch. These variations may be larger than 10 %.
Fine detail analysis
~ 10 %
IDPASC School on Digital Counting Photosensors for Extreme Low Light Levels, Lisbon 16 - 21 May 2010
L . Pereira 23
Effect of the earth magnetic field in the sensitivity pattern
X-Axis (mm)
Y-A
xis
(mm
)
25 30 35 40 45 5025
30
35
40
45
50
55
20 30 40 50 600
20
40
60
80
100X=38 mm
Y-Axis (mm)
Rel
ativ
e O
utpu
t (%
)
20 30 40 50 600
20
40
60
80
100Y=40 mm
X-Axis (mm)
Rel
ativ
e O
utpu
t (%
)
3040
50
3040
50
0
50
100
X-Axis (mm)Y-Axis (mm)
Rel
ativ
e O
utpu
t (%
)
10
20
30
40
50
60
70
80
90
100
SN6203, 1Kv, 395nm, 0degrees
X-Axis (mm)
Y-A
xis
(mm
)
30 40 5025
30
35
40
45
50
55
20 30 40 50 600
20
40
60
80
100X=39 mm
Y-Axis (mm)
Re
lativ
e O
utp
ut (
%)
10 20 30 40 50 600
20
40
60
80
100Y=40 mm
X-Axis (mm)
Re
lativ
e O
utp
ut (
%)
20
40
20
40
600
50
100
X-Axis (mm)Y-Axis (mm)
Re
lativ
e O
utp
ut (
%)
20
40
60
80
100
SN6203, 1Kv, 395nm, 180degrees
Position 1, 0º Position 2, 180º
IDPASC School on Digital Counting Photosensors for Extreme Low Light Levels, Lisbon 16 - 21 May 2010
L . Pereira 24
3040
5040
600
50
100
Hamamatsu R5070A, SN6203, 1 kV, 395 nm, 0º, w/ Mag. Shielding
X-Axis (mm)Y-Axis (mm)
Re
lativ
e O
utp
ut (
%)
X-Axis (mm)
Y-A
xis
(mm
)
25 30 35 40 45
35
40
45
50
55
30 35 40 45 50 55 600
20
40
60
80
100X=35 mm
Y-Axis (mm)
Re
lativ
e O
utp
ut (
%)
20 25 30 35 40 45 500
20
40
60
80
100Y=44 mm
X-Axis (mm)
Re
lativ
e O
utp
ut (
%)
10
20
30
40
50
60
70
80
90
100
X-Axis (mm)
Y-A
xis
(mm
)
25 30 35 40 45 50
35
40
45
50
55
60
30 40 50 600
20
40
60
80
100X=36 mm
Y-Axis (mm)
Rel
ativ
e O
utpu
t (%
)
20 25 30 35 40 45 50 550
20
40
60
80
100Y=45 mm
X-Axis (mm)
Rel
ativ
e O
utpu
t (%
)
20
4040
600
50
100
X-Axis (mm)Y-Axis (mm)
Rel
ativ
e O
utpu
t (%
)
20
40
60
80
100
SN6203, 1Kv, 395nm, 180degrees, Magnetic Shielding
With magnetic shielding (mu-metal)
Pos 1 , 0º Pos 2 , 180º
IDPASC School on Digital Counting Photosensors for Extreme Low Light Levels, Lisbon 16 - 21 May 2010
L . Pereira 25
Wavelength dependence
λ = 395 nm λ = 630 nm
0 5 10 15 20 25 300
20
40
60
80
100
X (mm)
RE
LA
TIV
E O
UT
PU
T (
%)
SN: HB6186, = 395 nm, Y = 18 mm
X (mm)
Y (
mm
)
SN: HB6186, = 395 nm
0 5 10 15 20 25 30
5
10
15
20
25
30
0
20
40
60
80
100
0 5 10 15 20 25 300
20
40
60
80
100
X (mm)
RE
LA
TIV
E O
UT
PU
T (
%)
SN: HB6186, = 630 nm, Y =15 mm
X (mm)
Y (
mm
)
SN: HB6186, = 630 nm
0 5 10 15 20 25 300
5
10
15
20
25
30
0
20
40
60
80
100
IDPASC School on Digital Counting Photosensors for Extreme Low Light Levels, Lisbon 16 - 21 May 2010
L . Pereira 26
Angle dependence of the anode sensitivity: Experimental system
Step motor: 1.8º / step
Δθ = 1.8º
AXES OF ROTATION
30 mm
0 20 40 60 80
1
10
100
ANGLE (º)
SP
OT
MA
JOR
AX
IS (
mm
)
ANGLE = 87ºSPOT DIAMETER > 19 mm
IDPASC School on Digital Counting Photosensors for Extreme Low Light Levels, Lisbon 16 - 21 May 2010
L . Pereira 27
-80 -40 0 40 800
0.2
0.4
0.6
0.8
1
1.2HORIZONTAL LEFT
ANGLE
RE
LA
TIV
E O
UT
PU
T
-80 -40 0 40 800
0.2
0.4
0.6
0.8
1
1.2CENTER
ANGLE-80 -40 0 40 80
0
0.2
0.4
0.6
0.8
1
1.2HORIZONTAL RIGHT
ANGLE
-80 -40 0 40 800
0.2
0.4
0.6
0.8
1
1.2VERTICAL UP
ANGLE
RE
LA
TIV
E O
UT
PU
T
-80 -40 0 40 800
0.2
0.4
0.6
0.8
1
1.2DIAGONAL
ANGLE-80 -40 0 40 80
0
0.2
0.4
0.6
0.8
1
1.2VERTICAL DOWN
ANGLE
λ = 395 nm
V. UP
V. DOWN
H. LEFT H. RIGHTCENTER
DIAGONAL
-+
6 mm
IDPASC School on Digital Counting Photosensors for Extreme Low Light Levels, Lisbon 16 - 21 May 2010
L . Pereira 28
-80 -40 0 40 800
0.2
0.4
0.6
0.8
1
1.2
HORIZONTAL LEFT
ANGLE
RE
LA
TIV
E O
UT
PU
T
-80 -40 0 40 800
0.2
0.4
0.6
0.8
1
1.2
CENTER
ANGLE-80 -40 0 40 80
0
0.2
0.4
0.6
0.8
1
1.2
HORIZONTAL RIGHT
ANGLE
-80 -40 0 40 800
0.2
0.4
0.6
0.8
1
1.2
VERTICAL UP
ANGLE
RE
LA
TIV
E O
UT
PU
T
-80 -40 0 40 800
0.2
0.4
0.6
0.8
1
1.2
DIAGONAL
ANGLE-80 -40 0 40 80
0
0.2
0.4
0.6
0.8
1
1.2
VERTICAL DOWN
ANGLE
λ = 630 nm
V. UP
V. DOWN
H. LEFT H. RIGHTCENTER
DIAGONAL
-+
6 mm
IDPASC School on Digital Counting Photosensors for Extreme Low Light Levels, Lisbon 16 - 21 May 2010
L . Pereira 29
Main parameters
Fix
PMTsConfiguration: 7 HexagonaldPMT center-to-center: 27 mmWindow: borosilicateWindow thickness: 5mm
Simulation parametersNº of neutrons: 1000 Photons per neutron in 4π: 360000Event location algorithm: Center of gravity (Anger)
Scintillation spectrum CF4 - 5 bar
Variable
PMT diameter: 21 mm (effective) or 25 mm (w/ experimental uniformity maps)PMT-MS : 10 mm e 15 mmAngular dependence: ACTIVATEd (w/ exp. data) / NOT ACTIVATEDUniformity: ACTIVATED (w/ exp. data) / NOT ACTIVATED
Simulations with ANTSAnger-camera Neutron detector Toolkit for Simulation
[ Andrei Morozov: [email protected] ]
IDPASC School on Digital Counting Photosensors for Extreme Low Light Levels, Lisbon 16 - 21 May 2010
L . Pereira 30
IDPASC School on Digital Counting Photosensors for Extreme Low Light Levels, Lisbon 16 - 21 May 2010
L . Pereira 31
Distance between the MSCG plane and PMTs = 15 mm
X (mm) Y (mm) Res. X (mm) Res. Y (mm) 0 0 0.717 0.74219.5 0 0.655 0.78613.5 6.5 0.605 0.601
X (mm) Y (mm) Res. X (mm) Res. Y (mm) Var. Res. X (%) Var. Res. Y (%)0 0 0.635 0.623 -9 -1219.5 0 0.343 0.556 -8 -1113.5 6.5 0.282 0.290 -8 -5
X (mm) Y (mm) Res. X (mm) Res. Y (mm) Var. Res. X (%) Var. Res. Y (%)0 0 0.636 0.623 -7 -1319.5 0 0.365 0.550 0 -213.5 6.5 0.293 0.315 -6 -1
σ < 2%
Table 1 Flat uniformity and angular dependence.
Table 2 Angular dependence.
Table 3 Uniformity and angular dependence considered.
IDPASC School on Digital Counting Photosensors for Extreme Low Light Levels, Lisbon 16 - 21 May 2010
L . Pereira 32
The End