FORWARD ATLAS {major contributions from Per Grafstrom (CERN), Michael Rijssenbeek (Stonybrook), Brian Cox (Manchester} Andrew Brandt Luminosity measurement for ATLAS (based on update at Freiberg in October) Forward Physics with ATLAS

1) Roman pots for Luminosity measurement 2) LUCID-cerenkov detector for Lum monitoring LOI submitted in March 2004, approved by ATLAS management in summer

Absolute Luminosity from Coulomb Scattering Elastic scattering at micro-radian angles :  L directly determined in a fit (along with  TOT,  and  b) effectively a normalization of the luminosity from the exactly calculable Coulomb amplitude Required reach in t : Requires:  small intrinsic beam angular spread at IP  insensitive to transverse vertex smearing  large effective lever arm L eff  detectors close to the beam, at large distance from IP (240 m) Parallel–to–point focusing

ECR for Installation

Roman Pot Detectors Square scintillating fibers  Kuraray 0.5 mm × 0.5 mm fibers  10 layers per coordinate  50 μm offset between layers scintillator plate for triggering y-measurement detector x-measurement detector proposed UTA responsibility in LOI—could include trigger electronics as well

List of tasks and deliverables leading to the construction of a prototype fiber detector design optimization (fiber layout, staggering, fiber routing) selection and characterization of components  scintillating fibers: optical, geometrical and mechanical parameters (single vs. double cladding) development and demonstration of production techniques  fiber cutting, polishing, bending, gluing interfacing fibers to photo detectors  bundling of fibers and couple to the photo detector  defining a concept for a vacuum tight fiber window construction and characterization of at least 2 fiber layers  analysis of geometrical precision  determination of cross-talk  determination of light yield for MIPs

Points with no or little progress Design and construction of the pot  Need institute with interest in mechanical engineering Development of a detector integration concept Establishing a collaboration for the scintillating fiber detector Precision movements of the pots  Motors  Control Selection and characterization of the photo detector Lots of room for UTA to make an impact given resources

Conclusion A lot of progress since overview week in Prague  LOI  Optics  ECR to the machine  Start of developing work for a prototype detector  Collaboration is starting on front-end electronics Not enough progress to form a collaboration to be able to see a clear timeline for a working system