Forward scintillators in ATLAS: cryostat and MBTS CERN Dubna Michigan State University University of Texas-Arlington presented by J. Huston Michigan State University (apologies: some useful drawings captive on laptop, in for repairs)

E3 C10 B11 E1 D5 A14 - A15 B14 D6 A D4 A12 A13 B12 - B B ITC Scintillators (cryostat (or crack) scintillators) (gap scintillators)

Crack Scintillator (E3, E4)

Mounting Proposal

View of 2 cryostat shells mounting bracket

Closeup

Bracket in final position

Special ITC brackets

Inner radius Counters held together by pins in one module fitting into slots in neighbor module

Cryostat scintillator status as of 2004 Optics, PMT’s, electronics and even mechanical shells were available Scintillator purchase was a victim of management contingency and the cryostat scintillators were on the upgrade path In the last few months, thanks to Marzio and Howard Gordon, the money is now available for construction and installation Scintillator has been shipped from CERN to MSU yesterday  ~2.5 month delay Construction will still be complete during summer …and,to save money, we will use polystyrene scintillator provided by Dubna, rather than the PVT scintillator from Bicron; factor of 2 less light yield, i.e. more like 2-3 pe/mip calibration issues Same WLS fibers as for gap scintillators

MBTS counters 2 segments in  ; inner segment covers pixel detectors

Readout Scintillator is polystyrene- based, 2 cm thick Readout is by WLS fibers running along division between L/R scintillator segments plus through sigma grooves in scintillator Struggle to be able to trigger on MIP’s  increase light yield using every trick we know Will also crank up HV to 900 V WLS fibers welded to clear fibers to produce a pigtail which will mate into 1/8 of cryostat scintillator optical connections  after commissioning cryostat detectors will be re-connected

Scintillator Scintillator has been produced by Dubna  same scintillator as used for CDF central pre-radiator upgrade  currently at CERN, awaiting shipment to MSU later this week  ~2.5 month delay…  …construction will still be complete in September  will continue to test counters using ATLAS electronics readout chain at the U. of Chicago  …and installation will take place this fall/winter

New decision MBTS scintillator and boronated polyethylene moderator will be mounted together in same can  MBTS counters are never removed; they just slowly die but continue to moderate Moderator has to be machined back to 30 mm  currently looking for vendor  envelope of MBTS + moderator is 57 mm

New drawings of moderator + MBTS …still have to be approved

MBTS drawings

Installation work This fall/winter, the gap and cryostat scintillators will be installed on EBA and EBC  maybe delay in current schedule, but roughly Nov and Jan During these times, teams from the institutions listed on front page will be at CERN and will also work on installation of MBTS counters + moderator  working with shielding group  all details not worked out yet, but Ron Richards is at CERN for next few weeks to coordinate  installation is designed to be relatively straightforward