Jlab Summer Lecture Series Introduction Components Scintillator Light Guides Light Sensors Photomultiplier Tubes Silicon Photomultipliers Formalism Electronics Application to Particle Identification ID: 722917
Download Presentation The PPT/PDF document "Scintillation Detectors Elton Smith" is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.
Slide1
Scintillation Detectors
Elton Smith -- Jlab Summer Lecture Series
Introduction
Components
Scintillator
Light Guides
Light Sensors
Photomultiplier Tubes
Silicon Photomultipliers
Formalism
/Electronics
Application to Particle IdentificationSlide2
Elton Smith / Scintillation Detectors
B field ~ 5/3 T
R = 3m
L =
½
p
R = 4.71 m
p = 0.3 B R = 1.5 GeV/c
t
p
= L/
b
p
c = 15.77 ns
t
K
= L/
b
K
c = 16.53 ns
D
tpK = 0.76 ns
Experiment basics
b
p = p/√p2+mp2 = 0.9957
bK = p/√p2+mK2 = 0.9496 Slide3
Elton Smith / Scintillation Detectors
B field ~ 5/3 T
R = 3m
L =
½
p
R = 4.71 m
p = 0.3 B R = 1.5 GeV/c
t
p
= L/
b
p
c = 15.77 ns
t
K
= L/
b
K
c = 16.53 ns
D
tpK = 0.76 ns
Experiment basics
b
p = p/√p2+mp2 = 0.9957
bK = p/√p2+mK2 = 0.9496
Particle Identification by time-of-flight (TOF) requires
Measurements with accuracies of ~ 0.1 nsSlide4
Elton Smith / Scintillation Detectors
Measure the Flight Time between two Scintillators
400 cm
100 cm
300 cm
20 cm
Disc
Disc
TDC
Start
Stop
450 nsSlide5
Elton Smith / Scintillation Detectors
Measure the Flight Time between two Scintillators
400 cm
100 cm
300 cm
20 cm
Disc
Disc
TDC
Start
Stop
Particle Trajectory
450 nsSlide6
Elton Smith / Scintillation Detectors
Propagation velocitiesc = 30 cm/nsvscint
= c/n = 20 cm/ns
v
eff
= 16 cm/ns
vpmt = 0.6 cm/nsvcable = 20 cm/nsDt ~ 0.1 nsDx ~ 3 cmSlide7
Elton Smith / Scintillation Detectors
CLAS detector with FC pulled apartSlide8
Elton Smith / Scintillation Detectors
Start counter assemblySlide9
Elton Smith / Scintillation Detectors
Scintillator typesOrganicLiquid
Economical
messy
Solid
Fast decay time
long attenuation lengthEmission spectraInorganic (crystals)AnthraceneUnused standardNaI, CsIExcellent g resolution
Slow decay timeLead Tungstate (PbWO4
)High density and resolutionSlide10
Elton Smith / Scintillation Detectors
Scintillator typesOrganicLiquid
Economical
messy
Solid
Fast decay time
long attenuation lengthEmission spectraInorganic (crystals)AnthraceneUnused standardNaI, CsIExcellent g resolution
Slow decay timeLead Tungstate (PbWO4
)High density and resolutionSlide11
Elton Smith / Scintillation Detectors
Light Spectrum
Photomultipliers and Accessories
Electron Tubes Ltd (1996) Slide12
Elton Smith / Scintillation Detectors
Light Collection: Light guidesGoalsMatch (rectangular) scintillator to (circular) pmt
Optimize light collection for applications
Types
Plastic
AirNone
“Winston” shapesSlide13
Elton Smith / Scintillation Detectors
acrylic
Reflective/Refractive boundaries
Scintillator
n = 1.58
PMT glass
n = 1.5Slide14
Elton Smith / Scintillation Detectors
acrylic
Reflective/Refractive boundaries
Scintillator
n = 1.58
PMT glass
n = 1.5Slide15
Elton Smith / Scintillation Detectors
mirror
Reflective/Refractive boundaries
Scintillator
n = 1.58
PMT glass
n = 1.5
AirSlide16
Elton Smith / Scintillation Detectors
mirror
Reflective/Refractive boundaries
Scintillator
n = 1.58
PMT glass
n = 1.5
(reflectance at normal incidence)
AirSlide17
Elton Smith / Scintillation Detectors
Reflective/Refractive boundaries
Scintillator
n = 1.58
PMT glass
n = 1.5
airSlide18
Elton Smith / Scintillation Detectors
Reflective/Refractive boundaries
Scintillator
n = 1.58
PMT glass
n = 1.5
airSlide19
Elton Smith / Scintillation Detectors
Reflective/Refractive boundaries
Scintillator
n = 1.58
PMT glass
n = 1.5
airSlide20
Elton Smith / Scintillation Detectors
acrylic
Reflective/Refractive boundaries
Scintillator
n = 1.58
PMT glass
n = 1.5
Acceptance of incident rays at fixed angle depends
on position at the exit face of the scintillatorSlide21
Elton Smith / Scintillation Detectors
acrylic
Reflective/Refractive boundaries
Scintillator
n = 1.58
PMT glass
n = 1.5
Acceptance of incident rays at fixed angle depends
on position at the exit face of the scintillatorSlide22
Elton Smith / Scintillation Detectors
acrylic
Reflective/Refractive boundaries
Scintillator
n = 1.58
PMT glass
n = 1.5
Large-angle
ray lost
Acceptance of incident rays at fixed angle depends
on position at the exit face of the scintillator
Rule of thumb:
Acceptance is given by the ratio of output/input areasSlide23
Elton Smith / Scintillation Detectors
Winston Cones - special geometry
Rev
. Sci.
Instrum
. 41 (1970) 413-418Slide24
Elton Smith / Scintillation Detectors
Photomultiplier tube, sensitive light meter
Photocathode
Electrodes
N Dynodes
Anode
56 AVP pmt
Gain ~ V
N
~ 10
6
- 10
7Slide25
Elton Smith / Scintillation Detectors
Photomultiplier tube, sensitive light meter
Photocathode
Electrodes
N Dynodes
Anode
56 AVP pmt
g
e
−
Gain ~ V
N
~ 10
6
- 10
7
Photomultiplier Tubes
Principles and Applications,
Photonis
(2002)Slide26
Elton Smith / Scintillation Detectors
High voltagePositive (cathode at ground)low noise, capacitative coupling
Negative
Anode at ground (no HV on signal)
No (high) voltage
Cockcroft-Walton basesSlide27
Elton Smith / Scintillation Detectors
Housing
NIM A432
(
1999) 265Slide28
Elton Smith / Scintillation Detectors
Compact divider designSlide29
Elton Smith / Scintillation Detectors
Single photoelectron signalSlide30
PMT single p.e
. spectra (noise)Elton Smith / Scintillation Detectors
ADC (counts)
ADC (counts)Slide31
Elton Smith / Scintillation Detectors
Signal for passing tracksSlide32
Elton Smith / Scintillation Detectors
Energy deposited in scintillatorSlide33
Elton Smith / Scintillation Detectors
Energy deposited in scintillator
Minimum-ionizing peak
pions
, electronsSlide34
Elton Smith / Scintillation Detectors
Energy deposited in scintillator
Minimum-ionizing peak
pions
, electrons
Photons and “corner clippers”Slide35
Elton Smith / Scintillation Detectors
Effect of magnetic field on pmt
Photomultipliers and Accessories
Electron Tubes Ltd (1996) Slide36
Tagger Spectrometer
(Upstream)
Hermetic detection
of charged and
neutral particles in
solenoid magnet
Hall D – GlueX detector
Time-
of-flight
(tof)
Pb-glass detector (Fcal)
Barrel
Calorimeter
(Bcal)
Target
(LH
2
)
Tracking
Cathode strips
Drift chambers
Straw tubesFuture PID detector
Superconducting 2 T solenoidInitial Peak Flux
107 g/s 18,000 FADCs4,000 pipeline TDCs
5
0
KHz L1 trigger600 MB/s to tapeSlide37
Tagger Spectrometer
(Upstream)
Hermetic detection
of charged and
neutral particles in
solenoid magnet
Hall D – GlueX detector
Time-
of-flight
(tof)
Pb-glass detector (Fcal)
Barrel
Calorimeter
(Bcal)
Target
(LH
2
)
Tracking
Cathode strips
Drift chambers
Straw tubesFuture PID detector
Superconducting 2 T solenoidInitial Peak Flux
107 g/s 18,000 FADCs4,000 pipeline TDCs
5
0
KHz L1 trigger600 MB/s to tapeWhat to do in a Magnetic Field?Slide38
Some history in photos
Elton Smith / Scintillation DetectorsSlide39
Multipixel
Limited Geiger mode APD
20
-100 µ
m
Geiger APD
pixel
Incident photon initiates avalanche
Quenched
by resister
device reset
Sum
the pixels –> photon counter
Quenching
Resister
Geiger-APD array
Photosensitive surface
R
QSlide40
Multipixel
Limited Geiger mode APD
20
-100 µ
m
Geiger APD
pixel
Incident photon initiates avalanche
Quenched
by resister
device reset
Sum
the pixels –> photon counter
Quenching
Resister
Geiger-APD array
Photosensitive surface
R
Q
Insensitive to Magnetic Fields!Slide41
Hamamatsu S12045 arrays
Elton Smith / Scintillation Detectors
4x4 array of 3x3 mm
2
sensor
Area = 12.7
x 12.7 mm257600 pixels
NIM A896 (2018) 24Slide42
SiPM (3x3 mm
2) single p.e. spectraElton Smith / Scintillation Detectors
Dark Counts
Filter=1%
Filter=2%
Filter=4%
Filter=6%
PedestalSlide43
Elton Smith / Scintillation Detectors
Measure the Flight Time between two Scintillators
400 cm
100 cm
300 cm
20 cm
Disc
Disc
TDC
Start
Stop
Particle Trajectory
450 nsSlide44
Elton Smith / Scintillation Detectors
Formalism: Measure time and position
Mean is independent of position!Slide45
Elton Smith / Scintillation Detectors
B field ~ 5/3 T
R = 3m
L =
½
p
R = 4.71 m
p = 0.3 B R = 1.5 GeV/c
t
p
= L/
b
p
c = 15.77 ns
t
K
= L/
b
K
c = 16.53 ns
D
tpK = 0.76 ns
Experiment basics
b
p = p/√p2+mp2 = 0.9957
bK = p/√p2+mK2 = 0.9496 Slide46
Elton Smith / Scintillation Detectors
Particle ID by “tof”: b vs
p
plot
p
+
K+
pSlide47
Elton Smith / Scintillation Detectors
SummaryScintillation counters
have a few simple components
Trigger and time-of-flight systems
are built out of these counters
Fast response allows for accurate
timingNew solid-state light sensors are now available, which allow use in high magnetic fieldsCombining the timing information from scintillator detectors with momentum measurements from tracking detectors, one can determine the mass of passing particles.Slide48
Backup slides
Elton Smith / Scintillation DetectorsSlide49
Elton Smith / Scintillation Detectors
Electronics
trigger
dynode
Measure time
Measure pulse height
anodeSlide50
Elton Smith / Scintillation Detectors
Formalism: Measure energy loss
Geometric mean is independent of position!Slide51
Elton Smith / Scintillation Detectors
Example: Kaon mass resolution by TOF
For a flight path of
d
= 500 cm
Assume experimental resolutions of