1. Andrew BrandtSept 13 th 2005FP420/Cerenkov Intro 1 Location of LHC in France and Switzerland, with lake Geneva and the Alps in the background The ATLAS detector is currently being built at UTA and at 100's of other institutions all over the world Proton-proton collisions at 14 TeV

2. Andrew BrandtSept 13 th 2005FP420/Cerenkov Intro 2 FP420 = Forward Protons 420m downstream of CMS & ATLAS Physics is p H/WW/ZZ p Measure p’s with very high precision within 3 mm of beam  mass and quantum numbers of central state. We are talking ~ 5 microns on track over 10m, and 10 ps timing Challenges include (detectors ~ 6mm x 24 mm):  Tracker, perhaps 10 layers per station, 3 stations, 3D silicon (edgeless, 10um res., fast, rad hard).... Hawaii/SLAC + Brunel  TOF counter, quartz fiber Cerenkov + MCP-PMTs  Vacuum mechanics: Detectors in secondary vacuum, Space constraints (Cryo talk), between beam pipes, not roman pots (Micro talk) High precision movement (microns), reproducibility, fail-safe.

3. Andrew BrandtSept 13 th 2005FP420/Cerenkov Intro 3 We have LOI to LHCC for R&D project (combined CMS/TOTEM & ATLAS) Unofficially (so far) supportive Plan: R&D now  summer/fall 2006. Make choices among options, design arms. Go to CMS & ATLAS to propose that it be an upgrade (not separate project) Hope for installation late 2008/2009 Proposed (Fermilab) test beam scenario: Integrate with the BTeV/CMS tracker in place, with its readout etc Mount each (of 2) prototype vacuum chambers, with (rough) vacuum, motions Microstation (Helsinki) and Hamburg Pipe (Louvain) with a BTeV/cms tracker layer installed and R/O... tests motion, reproducibilty and find problems to solve with mechanics, vacuum etc. Hopefully will also have some 3D Si detectors to put in beam (with BTeV R/O) (More) hopefully could have 2 S-TOF counters to test with MCP-PMT R/O

4. Andrew BrandtSept 13 th 2005FP420/Cerenkov Intro 4 Fermilab Test Beam... Erik Ramberg in charge Up to 120 GeV protons Up to 200K/spill (more than enough!) over ~ 5 mm x 5 mm Beam diagnostics: 3 MWPC profile monitors 4 layers x-y Silicon strip detectors BEAM MT6-B... another area behind http://www-ppd.fnal.gov/MTBF-w/ BTeV pixel & CMS pixel current users of area A

5. Andrew BrandtSept 13 th 2005FP420/Cerenkov Intro 5 Some views of present A1 set-up (Sep 8 2005) Side view, beam from L 2 views of exit

6. Andrew BrandtSept 13 th 2005FP420/Cerenkov Intro 6 Fast Timing Counters Counters with ~ 10 ps timing resolution behind tracking 10 ps = 3 mm 1) Check both p’s from same collision (reduce background) 2) Get z(vertex) to match with central track vertex 3) Tell what part of bunches interacting protons were (F-M-B) Likely solution: Solid Cerenkov block or fibers (quartz?) MCP-PMT (Micro-Channel Plate PMT)... or APD? (Cerenkov talk) Mike A + Jim Pinfold + others interested

7. Andrew BrandtSept 13 th 2005FP420/Cerenkov Intro 7 Photomultiplier Tube (PMT) PMTs consist of a photocathode and a series of dynodes in an evacuated glass enclosure. Photons that strikes the photoemissive cathode emits electrons due to the photoelectric effect. The electrons are accelerated towards a series of additional electrodes called dynodes. These electrodes are each maintained at a more positive potential. Additional electrons are generated at each dynode. This cascading effect creates 10 5 to 10 7 electrons for each photon hitting the first cathode depending on the number of dynodes and the accelerating voltage. This amplified signal is finally collected at the anode where it can be measured.

8. Andrew BrandtSept 13 th 2005FP420/Cerenkov Intro 8 Put at back of 420m (220m?) tracking high precision timing counters. Suggested in Tevatron LOI: Quartz Cerenkov + ~ Microchannel PMT Then said 30 ps(?). Now tested (Japanese Gp)  10 ps Check that p’s came from same interaction vertex (& as central tracks) tLtL tRtR x tLtL tRtR z_ vtx z t Know position in each bunch of interacting p’s. Position-momentum correlation  Reduce uncertainty in incoming momenta. t _int Potentially valuable e.g. MSSM triplet (Higher cross section & close states)

9. Andrew BrandtSept 13 th 2005FP420/Cerenkov Intro 9 It’s been done!

10. Andrew BrandtSept 13 th 2005FP420/Cerenkov Intro 10 Challenging, needs study: (1) 3D ray tracing program, with times Design a practical compact detector. Beam test. … great project for interested-in-instrumentation student/postdoc Geometry? Want max light in delta-function ug students at UTA Yushu Yao (Alberta) CUT AWAY Plates or Fibers Rectangular Block Tilted Can’t put MAPMT in front of 7 TeV protons!

11. Andrew BrandtSept 13 th 2005FP420/Cerenkov Intro 11 Cerenkov Project Steps Reading, understanding concepts, etc. 2-d ray tracing program to determine time distribution of light arrival 3-d version In parallel: calculate number of pe’s Build prototype (budget? readout?) Test in testbeam