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Comments on crystal LY losses due to 20GeV proton irradiation D Cockerill 29.1.2009

Comments on crystal LY losses due to 20GeV proton irradiation D Cockerill 29.1.2009. Data NIMA 545 Table 3 and Fig.18 NIMA 564 Fig 3 (top) Force fit through 0,0 Force fit through 54.10 12 p/cm2 Fit result 96*(1-exp(-0.13*flux) flux in units of 10 12 Chisq = 4 Note

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Comments on crystal LY losses due to 20GeV proton irradiation D Cockerill 29.1.2009

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  1. Comments on crystal LY losses due to 20GeV proton irradiationD Cockerill 29.1.2009 Data NIMA 545 Table 3 and Fig.18NIMA 564 Fig 3 (top) Force fit through 0,0Force fit through 54.1012 p/cm2 Fit result96*(1-exp(-0.13*flux) flux in units of 1012 Chisq = 4 Note MOST important data at ~10.1012 p/cm2Governs VERY fast appearance of damage at early stage !!!!!!!!!!!!! Less relative damage after 30.1012 LY loss (%) Proton flux*1012 / cm2

  2. Comments on crystal LY losses due to 20GeV proton irradiationD Cockerill 29.1.2009 Barrel Endcap LY loss (%) 100fb-1high L, 1yr 500fb-1end LHC 3500fb-1end SLHC 50fb-1 25fb-1 10fb-1LHC start Eta LY losses across the ECAL due to hadron generated ‘stars’

  3. Comments on crystal LY losses due to 20GeV proton irradiationD Cockerill 29.1.2009 Region of 50% LY loss or more, at end LHC (500fb-1) 56 SCs per Dee, 224 SCs (5600 crystals) in total for EE4 out of 25 ECAL eta ‘good’ trigger tower regions (to eta=2.5)

  4. Comments on crystal LY losses due to 20GeV proton irradiationD Cockerill 29.1.2009 • Significant, measurable effects at LHC startup (LOOK for them!) • Half light gone at eta=2 by end of standard LHC running • Wiped out by end of SLHC • BUT • What is light collection profile along xtals with star density creation • Cosmics data (NIMA 564) from whole xtal only • Very interesting to get LY with distance in new CR stand • May lose light on em showers (first 10 Xo) but not for hadron shower energy deposits which get right to back of xtal • ECAL could still be used as an HCAL layer 0 possibly at inner radii • To do: CHECK – these plots!

  5. Comments on crystal LY losses due to 20GeV proton irradiationD Cockerill 29.1.2009 • STRAWS to clutch at, in hope, • Proton irradiations done at VERY high rate - factor 140 vs normal LHC at injection • Could this leave a highly CHARGED xtal internally leading to odd 2nd order effects not normally seen? • Odd, Rayleigh scattering – totally unlike gamma colour centres • Odd, if crystaline effect, annealing possible at such a low temp (250-350oC) • Does xtal anneal faster/further at 100oC than at 20oC?? • Annealing with UV/other lamps, laser, double excitatation, focussed ultrasound, xrays • Bake out endcaps in shutdowns (not only LHC!) ?

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