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Study on CMS HF Light Guide Systems in LHC Project at University of Iowa

Detailed research on testing light guides in the CMS experiment at the LHC project, highlighting materials, shapes, and radiation hardness. Comparison between Al Mylar and HEM, and evaluation of X-Y uniformity and attenuation. Results show better performance with HEM and minimal radiation damage observed.

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Study on CMS HF Light Guide Systems in LHC Project at University of Iowa

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  1. 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

  2. OUTLINE • LHC project CMS experiment HF Calorimeter • Light Guide Tests on: Materials (Al Mylar and HEM ) Shapes ( straight , tapered ) Radiation hardness

  3. 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

  4. LHC • 14 TeV (Center of Mass Energy) proton-proton collisions at every 28 ns. • High Luminosity (1034 cm2s-1).

  5. 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.

  6. CMS DETECTOR Length : 21.6m Diameter : 14.6m Weight : 14500 tons Four main parts: Magnet, Muon system, tracking, calorimeter

  7. CMS detector

  8. 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

  9. HF Calorimeter

  10. Constructed parts of HF Cal

  11. 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

  12. LIGHT GUIDE TEST SETUP

  13. Setup (the box where the light isproduced)

  14. Setup (the box where the light guide stands)

  15. X uniformity without light guide

  16. Y uniformity without light guide

  17. X and Y uniformities with Al Mylar light guide

  18. X-Y uniformities with HEM (straight) light guide

  19. Light guide ratio comparison(HEM Straight / Al Mylar)

  20. Results obtained in the test beam

  21. TWO DIFFERENT SHAPES

  22. X-Y uniformities with HEM (tapered) light guide

  23. Light guide ratio comparisonHEM – (Straight / Tapered)

  24. RADIATION TESTS • Source: Cs137 at 9k Currie ( University of Iowa Hospitals and Clinics, Radiation Laboratories ) • 5 different irradiation levels: 2Mrad, 4Mrad, 6Mrad, 8Mrad, 10Mrad

  25. Irradiated/non-irradiated ratio (HEM) • Bullet 2mrad • Box 4mrad • Triangle 6mrad • Star 8mrad • Circle 10mrad

  26. Irradiated / non-irradiated ratio (Al Mylar) Output reduced by 15-17% after radiation

  27. 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

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