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Scintillation Detectors
John Neuhaus - University of Iowa Fall 2010
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John Neuhaus - University of Iowa Fall 2010
Basics Ionizing radiation excites matter, but doesn’t ionize De-excitation by heat, phosphorescence or fluorescence Fluorescence (ns timescale) in response to radiation is called scintillation John Neuhaus - University of Iowa Fall 2010
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John Neuhaus - University of Iowa Fall 2010
Details Light created proportional to energy deposited Fluorescence is fast! Pulse shape discrimination possible Basic two-part exponential decay John Neuhaus - University of Iowa Fall 2010
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Types of Scintillators
Organic Crystals Organic Liquids Plastics Inorganic Crystals Gaseous Scintillators Glasses John Neuhaus - University of Iowa Fall 2010
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John Neuhaus - University of Iowa Fall 2010
Organic Crystals Aromatic hydrocarbons, typically containing benzene rings Sometimes pure crystals (anthracene, stilbene) Decay time of few ns Light from free valence electrons (π orbitals) John Neuhaus - University of Iowa Fall 2010
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John Neuhaus - University of Iowa Fall 2010
Inorganic Crystals NaI(Tl), BGO, LYSO, PbWO4 High light, slower response (250 ns for NaI), high density (~7 g/ml for BGO, LYSO) Usually hygroscopic, expensive Make good gamma detectors John Neuhaus - University of Iowa Fall 2010
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John Neuhaus - University of Iowa Fall 2010
Organic Liquids Liquid solution of organic scintillators in organic solvent P-Terphenyl, PPO, etc. in xylene, toluene, cyclohexane, etc. Easily doped (e.g. with 10B for neutron detection) John Neuhaus - University of Iowa Fall 2010
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John Neuhaus - University of Iowa Fall 2010
Plastics Polymerizable solvent, like polystyrene or polyvinyltoluene High light, fast response, easily machineable and cheap Sensitive to body acids and organic solvents In fiber form -> wavelength shifting John Neuhaus - University of Iowa Fall 2010
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John Neuhaus - University of Iowa Fall 2010
Wavelength Shifting Solvents liquid and solid fluoresce, typically in UV Primary fluor (pTP, etc.) absorbs UV and re-emits at longer wavelength Secondary (3HF, POPOP) shifts further and inhibits self-absorption John Neuhaus - University of Iowa Fall 2010
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John Neuhaus - University of Iowa Fall 2010
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John Neuhaus - University of Iowa Fall 2010
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Radiation Damage Mechanisms
Damage of dopants Reduction in transmittance of base (“hidden damage”) BC505 Sample John Neuhaus - University of Iowa Fall 2010 Undoped base
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Methods of Improving Radiation Hardness
Rad-hard dyes Large Stokes’ shift dyes to move past damaged region Rad-hard bases Combos (e.g. 3HF and PDMS) John Neuhaus - University of Iowa Fall 2010
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Applications – Triggers and Vetos
Halo veto rejects poorly collimated beam John Neuhaus - University of Iowa Fall 2010
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John Neuhaus - University of Iowa Fall 2010
Applications – Cont’d Beam size trigger, selectable beam size John Neuhaus - University of Iowa Fall 2010
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John Neuhaus - University of Iowa Fall 2010
Applications – Cont’d Muon veto rejects beam events that contain muons Experiment High-z absorber John Neuhaus - University of Iowa Fall 2010
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John Neuhaus - University of Iowa Fall 2010
Applications – Cont’d Hodoscope, “path viewer” Track charged particles Onel, et al. 1998 John Neuhaus - University of Iowa Fall 2010
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John Neuhaus - University of Iowa Fall 2010
Test Beam Well characterized beam for detector R&D Single elements (e.g. scintillator plate) Full calorimeters FNAL (Mtest) and CERN (H2) John Neuhaus - University of Iowa Fall 2010
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John Neuhaus - University of Iowa Fall 2010
FNAL MTest John Neuhaus - University of Iowa Fall 2010
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John Neuhaus - University of Iowa Fall 2010
FNAL MTest John Neuhaus - University of Iowa Fall 2010
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John Neuhaus - University of Iowa Fall 2010
MTest Details Low Energy electrons (1-2 GeV) High Energy Protons (120 GeV) Pions (1-66 GeV) Muons (1-120 GeV) Multiple spill modes One 4s spill/min Two 1s spills/min Several ms spills/min John Neuhaus - University of Iowa Fall 2010
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John Neuhaus - University of Iowa Fall 2010
Beam Composition John Neuhaus - University of Iowa Fall 2010
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Calorimeter Experiments
Iowa Quartz Plate Calorimeter 2006 at FNAL, p-Terphenyl deposited quartz plates John Neuhaus - University of Iowa Fall 2010
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Calorimeter Exp Cont’d
QPCAL at CERN H2 Facility John Neuhaus - University of Iowa Fall 2010
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John Neuhaus - University of Iowa Fall 2010
Data from H2 John Neuhaus - University of Iowa Fall 2010
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