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Scintillation Detectors. 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. Details. Light created proportional to energy deposited
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Scintillation Detectors 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
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
Types of Scintillators • Organic Crystals • Organic Liquids • Plastics • Inorganic Crystals • Gaseous Scintillators • Glasses 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 (πorbitals) 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
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
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
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
Radiation Damage Mechanisms • Damage of dopants • Reduction in transmittance of base (“hidden damage”) BC505 Sample Undoped base John Neuhaus - University of Iowa Fall 2010
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
Applications – Triggers and Vetos • Halo veto rejects poorly collimated beam John Neuhaus - University of Iowa Fall 2010
Applications – Cont’d • Beam size trigger, selectable beam size 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
Applications – Cont’d • Hodoscope, “path viewer” • Track charged particles • Onel, et al. 1998 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
FNAL MTest John Neuhaus - University of Iowa Fall 2010
FNAL MTest 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
Beam Composition John Neuhaus - University of Iowa Fall 2010
Calorimeter Experiments Iowa Quartz Plate Calorimeter 2006 at FNAL, p-Terphenyl deposited quartz plates John Neuhaus - University of Iowa Fall 2010
Calorimeter Exp Cont’d QPCAL at CERN H2 Facility John Neuhaus - University of Iowa Fall 2010
Data from H2 John Neuhaus - University of Iowa Fall 2010
