INTAS Progress Report 2007: INTAS-CERN 05-103-7555Title: A proposal for R&D to establish the limitations

on the operation of the ATLAS end-cap calorimeters at high LHC luminosity

Coordinators: Peter Schacht, Sergei DenisovStart date: 8. 5. 2006

Energy fluxes at L=1034:η = 2.5 5.0*105 GeV/cm2/sη = 3.2 2.5*106 GeV/cm2/sη = 4.9 2.0*108 GeV/cm2/s

Main factors: ion’s mobility and recombination.Signal starts to degrade significantly above critical charge density.

In HEC and EMEC, should not exceed 5 %.In FCAL ~ 64 V at nominal of 250 V. The resistors sit on the rear HEC side.

Reducing gap size, shaping time…

“dE/dx” + ohmic heatingAdditional cooling loops in critical places, more powerful HV power supplies

Radiational damage of materials, activation

β-decay of Ar41: = 6560 s

After 100 days running at L=10**34:

98 GBq in EMEC, 50 in Barrel, 11 in HEC, 1.1 in FCAl_1, 0.5 in FCAl_2,3

After 7 more days of cool-down:

9.7 GBq in EMEC, 2.1 in Barrel, 6.5 in HEC, 19 in FCAl_1, 600 (?) in FCAl_2,3

LHC schedule (L.Evans & Dec 2006 Council):

last magnet installed March 07

machine closed August 07

450 GeV (lum~1029:1030, 75 ns between bunch crossings) November 07

7 TeV August 08

Calorimeters (plan of 20 February): end of access to

ECA - end of June, Barrel A – 15 July, Barrel C and ECC – 15 August

Problems:

calorimeters - LV power supplies (BNL and CERN, modified version should

be supplied starting from April)

Inner detector - SCT and TRT - heaters problem, Pixels on retard

LHC - failure of support structure of final focus “inner triplet” superconductive quadrupoles (1 of 28, all assembled by FNAL) during pressure test 27 March