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Scintillation Detectors and it’s Application. Particle interaction in matter Scintillation mechanism Inorganic scintillation detector Organic scintillation detector Light Sensor Application a) Nuclear, High energy, Astroparticle physics b) Astrophysics - PowerPoint PPT Presentation
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2002-6-24 여름학교
Scintillation Detectors and it’s Application
2002 년 6 월 24 일 , KNU Summer school
김 홍주 , 연세대학교
1) Particle interaction in matter2) Scintillation mechanism3) Inorganic scintillation detector4) Organic scintillation detector5) Light Sensor6) Application a) Nuclear, High energy, Astroparticle physics b) Astrophysics c) Bio-, Medical physics
2002-6-24 여름학교
Detectors use characteristic effects from interaction of particle with
matter to detect, identify and/or measure properties of particle; has “transducer” to translate direct effect into observable/recordable (e.g. electrical) signal
example: our eye is a photon detector; (photons = light “quanta” = packets of light)
“seeing” is performing a photon scattering experiment: light source provides photons photons hit object of our interest -- some absorbed, some
scattered, reflected some of scattered/reflected photons make it into eye; focused onto
retina; photons detected by sensors in retina (photoreceptors -- rods and
cones) transduced into electrical signal (nerve pulse) amplified when needed transmitted to brain for processing and interpretation
2002-6-24 여름학교
Overview of Experiment
detector signal processing
data handling
analysis&
control
01011101
computersimulation
PhysicsPhysics
origininteraction
2002-6-24 여름학교
Particle energy loss in matter
X rays
gamma rays
PE
CS
PP
electron(s)
dE/dx loss
charged particle
thermal neutronsnuclear reaction
energetic neutrons
proton
scintillator
dE/dx loss
dE/dx loss
2002-6-24 여름학교
Dependence ofType of interaction
Energy
Zcm2/atom
Zcm2/g
Photoelectric Effect E-3.5 Z4 to Z5 Z3 to Z4
Compton Effect E-0.5 to E-1 Z independentPair Production E1 to ln E Z2 Z
2002-6-24 여름학교
Scintillation detectors and sensors
Scintillators Light sensors
inorganic crystals organic plastics/liquid glass gas
PhotomultiplierMicrochannel platesilicon diodesCCDsAvalanch photo diodehybrid photo diode
In radiation detectionin solid state physics: luminescencefast < 1 ms: fluorescenceslow > 1 ms: phosphorescence
2002-6-24 여름학교
Scintillator
• Light emitted from ionisation in transport material( dE/dx loss)
a) I(t) = I0e-t/decay time, several component possible
b) s -> count rate<< MHz, ns -> count rate>> MHz, c) Wavelength of emission determine photosensor
• Two main material types of scintillators a) Inorganic scintillator b) Organic scintillator
2002-6-24 여름학교
Scintillator charasteristics• Inorganic scintillators a) Result of crystalline structure b) Large band gap, insulators c) High light output but relatively slow (~sec) d) Rather expensive, moderate size (~kg)
• Organic scintillators a) Molecular property of hidrocarbons b) Moderate light output but fast (~ns) c) Cheap, large size (~ton) d) Liquid scintillator (LSC) Plastic scintillator (PSC) Crystal (ex:anthracene, stibulene)
2002-6-24 여름학교
Inorganic Scintillator
• Ionisation excites electron conduction band de-excitation via photoemisson or radiationless
transition
• Large bandgap => slow process
• Impurities add centres (traps) in band gap Increase transition rate Suitable doping can also increase light output ( ex: CsI(tl), CsI(Na) Hols trapped at activate site -> recombination with e- -> emits photon
2002-6-24 여름학교
Organic Scintillator
• Based on excited states of carbon atom (benzene ring : C=C bonds) Quasi-free electrons confined to molecule Complex vibration stats gives fine structure Range of singlet and triplet stats gives both long and short time structure => neutron and gamma separation capability
• Chemical Mixing Solvent : Medium for absorbing the energy of nuclear recoil Energy transferred to 1st solute moleculs 1st Solute: highly efficient fluors (efficient scintillator) Very short wavelength 2nd Solute: Wavelength shifter to match with bi-alkali photo sensor
2002-6-24 여름학교
Organic solvent
Band gap structure Energy transfer mechanism
ns ms solute 1st solvent 2nd solvent
2002-6-24 여름학교
Organic scintillator Solvents• Solute
a) Liquid Scintillator 1,2,4-Trimethylbenzene (Pseudocumene) p-,m-,o-Xylene, Toluene, Benzene, MN…
a) Plastic Scintillator Polystyrene (Polyvinylbenzene, PS) Polyvinyltolunen (PVT) • 1st Solvent PPO, p-Terphenyl, PBD, Naphthalene..• 2nd Solvent POPOP, M2-POPOP, bis-MSB….
• Standard Liquid Scintillator : PC + PPO(1.5-4g/l) +POPOP(10-50mg) 65% of anthrecene, safe, Pulse shape discrimination of n/gamma
2002-6-24 여름학교Photomultiplier tube (PM or PMT)
generates electric signal
Light guide transmits light
to photodetector
Passage ofcharged particle generates lightin scintillator
Charged particle
Basic principles of operation
Scintillator light output readout
2002-6-24 여름학교
Light transmission
• Total reflection sin> next/n,
sin> 1/n, next = air
• Light guide• Optical grease (optical cement) • Light reflector Teflon, Al, white paint
2002-6-24 여름학교
PMT
PMTreflector
scintillator optical coupling
dynodes
photo cathode
electron multiplication
N
1
2
3 nNel
ideal case: Nel = N
Light detection
Photomultiplier Tube
2002-6-24 여름학교
PMT types
Venetian blind (old)
Box-and-grid
Focused linear structure
Circular grid
Gains - 107
PMTS
2002-6-24 여름학교
Difference between Crystal & LSC
Cs137 source(661 keV) to detector (GEANT4 simulation)
CsI crystal BC501A LSC
Quiz : Why different response?
2002-6-24 여름학교
Scintillator Application
• High energy physics BELLE, BES, CDF, L3, Phenix, CMS, LC, Focus … Many more!
• Astro-particle physics Neutrino ( LSND, Super-K, Kamland..), Underground( Darkmatter, neutrino,
double beta), Ground array ( HE neutrino, UHE cosmic ray, HE gamma)
• Nuclear Physics, Nuclear engineering. Neutron, Radioactive decay, heavy ion, radioactive beam. ; Power reactor
monitoring
• Astrophysics, Astronomy Balloon (ATIC, IMAX..), Satellite (GLAST, INTEGRAL..), Space station (AMS..)
• Bio-science: Track radioisotopes in biology sample, Quantifying DNA and RNA
• Medical science: PET, CT, Track radioisotopes in human body, medicine
• Environmental science: Monitoring of radioactivity, nuclear waste, Radon
• More :Safety inspection, Military …..
2002-6-24 여름학교
The BELLE Detector (B physics)
Charged particle tracking and vertexing
–SVD: 3 layer DSSD silicon microstrip –CDC: 50 layer drift chamber (50/50 He-C2H2)
• p = 0.46 % @ pt = 1.0 GeV/c
Particle identification
–Hadron ID•CDC: dE/dx in central drift chamber•TOF: Time-of-flight system•ACC: Cherenkov light threshold counters
–Electrons•ECL : E&M calorimeter E/p•CDC: dE/dx
–Muons•KLM: RPCs in magnetic return yoke
Neutral particle detection•Photons: E&M calorimeter•8800 CsI(tl) : 40ton•KL : direction in the KLM
2002-6-24 여름학교
DAMA experiment
DAMA NaI(Tl) crystal ~100 kg Gran sasso underground lab. Low threshold ~ 2keV Low background ~ 1/kg/kev/day Annual modulation method Found a evidence of WIMP
2002-6-24 여름학교
KIMS experiment Detector & Shielding Design(Dark matter Search experiment)
100kg 5 ton
2002-6-24 여름학교
Radioisotope imaging:Planar scintigraphy
Radiopharmaceutical
2D position sensitive detector:Gamma camera + motion
Multihole collimatorcrucial for image formation
emission
Radiation in Medical science
2002-6-24 여름학교
PET Scans(Positron Emission Tomography)
Scintillating crystal detectorand photomultiplier
3-D image
CrossSection
2002-6-24 여름학교
Radioisotope imaging:Planar scintigraphy
Phosphonate tagged with 99mTc,injected into the blood stream,is mainly transported to bones,producing a view of theskeletal systemThe method is e.g. used to determinewhether or not cancer has metastized
From: National Geographic 171/1(1987)2-41
Radiation Technology
2002-6-24 여름학교
1D position sensitiveX-ray detector
X-ray tubepoint source
transmission
Radiation in Aviation Security X-ray Application
Conveyor
Fan beam
1D + motion 2D
2002-6-24 여름학교
Radiation in Aviation Security X-ray Application
From: Heimann Systems, Wiesbaden, Germany
Advanced Multi X-ray Energy Method
2002-6-24 여름학교
Fan beam
Gamma-ray source
Moving truck or container
1D PSD
CsI(Tl) crystals integrating
Radiation in Border Control Gamma-ray Application
transmission
1D + motion 2D