JAMES F. JAKOBSEN GRADUATE FORUM 2003 STUDY ON CMS HF LIGHT-GUIDE SYSTEMS IN UNIVERSITY OF IOWA By FIRDEVS DURU DEPARTMENT OF PHYSICS AND ASTRONOMY
OUTLINE • LHC project CMS experiment HF Calorimeter • Light Guide Tests on: Materials (Al Mylar and HEM ) Shapes ( straight , tapered ) Radiation hardness
LHC PROJECT • LHC (Large Hadron Collider) is an accelerator • The LHC will be built on the France-Switzerland border west of Geneva • Will start running at 2007
LHC • 14 TeV (Center of Mass Energy) proton-proton collisions at every 28 ns. • High Luminosity (1034 cm2s-1).
CMS EXPERIMENT • CMS (Compact Muon Solenoid) detector has been designed to detect cleanly the diverse signatures from new physics by identifying and precisely measuring muons, electrons and photons over a large energy range and at high luminosity. • The main physics interests: Standard Model (SM) Higgs boson Minimum Supersymmetric Standard Model (MSSM) Higgs bosons Gluino, squark searches.
CMS DETECTOR Length : 21.6m Diameter : 14.6m Weight : 14500 tons Four main parts: Magnet, Muon system, tracking, calorimeter
HF Calorimeter • 11 m away from interaction point • Identification of very forward jets from heavy Higgs production • High radiation region (~1 Grad of radiation field near beam pipe) • Quartz fibers (QQ, QP) • Iron as absorber • LIGHT GUIDES • PMT’s
PURPOSE OF THE LIGHT GUIDE TESTS • Test the effect of the light guides on the uniformity of the PMT Signal by measuring the X-Y uniformity and attenuation[Optical properties – mixing] • Comparison of the tapered light guides vs. non-tapered ones. • Comparison of the different types of reflective materials (HEM, Al Mylar) • Test the effect of radiation on two materials
RADIATION TESTS • Source: Cs137 at 9k Currie ( University of Iowa Hospitals and Clinics, Radiation Laboratories ) • 5 different irradiation levels: 2Mrad, 4Mrad, 6Mrad, 8Mrad, 10Mrad
Irradiated/non-irradiated ratio (HEM) • Bullet 2mrad • Box 4mrad • Triangle 6mrad • Star 8mrad • Circle 10mrad
Irradiated / non-irradiated ratio (Al Mylar) Output reduced by 15-17% after radiation
CONCLUSION • Better results with HEM PMT X-Y uniformity improves and goes to a plateau when HEM reflecting material is used • No significant difference between tapered and straight light guides • No radiation damage was observed for HEM Output decrease in irradiated Al Mylar