160 likes | 267 Vues
Cherenkov Tracking Calorimeters. D. Casper University of California, Irvine. Outline. Overview Basic performance around 1 GeV Neutrino response. Acknowledgements and Caveats. Some work done together with: J. Dunmore, C. Regis (UCI)
E N D
Cherenkov Tracking Calorimeters D. CasperUniversity of California, Irvine
Outline • Overview • Basic performance around 1 GeV • Neutrino response D. Casper, UC Irvine
Acknowledgements and Caveats • Some work done together with: • J. Dunmore, C. Regis (UCI) • J. Burguet-Castell, E. Couce, J.J. Gomez-Cadenas, P. Hernandez (Valencia) • Thanks to: • M. Fechner (Saclay) • Super-Kamiokande and T2K Collaborations • Disclaimers • Not “official” results of any experiment except where noted • Intended as a generic overview • Hybrid (Cherenkov/Scintillation) detectors not considered explicitly D. Casper, UC Irvine
Motivations • Fully active target • Inexpensive detecting medium • Surface instrumentation • PMT cost scales like (Mass)2/3 • Long attenuation length • Size limited primarily by cavern excavation • Originally designed for proton decay searches D. Casper, UC Irvine
What Is Measured • PMT timing • Coincidence trigger • Vertex position • Delayed coincidence • e decay • Nuclear de-excitation • Neutron capture • Cherenkov rings • Particle directions from angle constraint • Showering/Non-showering topology for particle ID • PMT pulse heights • Energies from calorimetry and/or range D. Casper, UC Irvine
Cherenkov Detectors • First Generation (1982-1992) • IMB (3.3 kton, 1% 4.5%) • Kamiokande (0.78 – 1.1 kton, 20%) • Harvard-Purdue-Wisconsin • Second Generation (1996-Present) • Super-Kamiokande (22.5 kton, 40%) • SNO (1.0 kton, 55%) • K2K (0.025 kton, 40%) • Next Generation (ca. 2010+) • T2K 2km (0.025 kton, 40%) • Hyper-Kamiokande (~1 Mton, 40%) • etc… D. Casper, UC Irvine
Basic Performance near 1 GeV • Vertex resolution: ~20-30 cm • Challenge to control the fiducial volume of a small detector • Direction resolution: 2-3° • Negligible compared to neutrino-lepton scattering angle • e/ mis-ID: ~0.4%/ (%photocathode) • For equal e/ purity and efficiency • Verified in test beam • Energy resolution: ~2%/( Evis)1/2 • Additional energy scale uncertainty: 2-3% • Muon decay efficiency: ~95% (+), ~75% () • 22% capture probability in water D. Casper, UC Irvine
Neutrino Response • Response (1-ring mu-like sample) • Super-beam disappearance signal • Super-beam appearance background • Beta-beam appearance signal • e Response (1-ring e-like sample) • Super-beam appearance signal • Beta-beam disappearance signal • Beta-beam appearance background D. Casper, UC Irvine
Does Size Matter? • For a given photo-cathode coverage, greater pixelization helps reduce 0e • For a given photo-cathode coverage, a larger detector performs better at e/mu and e/0 separation D. Casper, UC Irvine
Cross-Sections D. Casper, UC Irvine
CCQE Efficiency Loss of partiallycontained Losses to 0 cuts Fully-contained e CCQE 1-ringe-like efficiency Fully-contained CCQE 1-ringmu-like efficiency D. Casper, UC Irvine
Signal and Backgrounds 1-ring -like sample 1-ring e-like sample D. Casper, UC Irvine
Contamination vs. Smearing 1-ring -like sample 1-ring e-like sample D. Casper, UC Irvine
CC Energy Transfer Matrices CCQE CC1 CC Other D. Casper, UC Irvine
Higher Energies • Possible to use hadronic calorimetry at higher energies • Does not help with particle ID • Possible to identify clean sample of high-energy muons from interactions outside the detector • “Upward-going muons” • May be able to say something about energy using angle(?) D. Casper, UC Irvine
Conclusions • A very mature and powerful technology • Backgrounds to low-medium energy super-beams or beta beams are fairly manageable • Depends on details of beam, baseline, etc. • Energies above 1.5-2 GeV create difficulties • May be mitigated by migration D. Casper, UC Irvine