FP420Cerenkov Intro

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FP420/Cerenkov Intro
Location of LHC in France and Switzerland, with
lake Geneva and the Alps in the background
Proton-proton collisions at 14 TeV
The ATLAS detector is currently being built
at UTA and at 100's of other institutions
all over the world
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• FP420 Forward Protons 420m downstream of CMS
  ATLAS
• Physics is p
  H/WW/ZZ p
• Measure ps 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.

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We have LOI to LHCC for RD project (combined
CMS/TOTEM ATLAS) Unofficially (so far)
supportive Plan RD 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
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Fermilab Test Beam ... Erik Ramberg in charge
http//www-ppd.fnal.gov/MTBF-w/
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

BTeV pixel CMS pixel current users of area A
BEAM
MT6-B ... another area behind
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Some views of present A1 set-up (Sep 8 2005)
Side view, beam from L
2 views of exit
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Fast Timing Counters
Mike A Jim Pinfold others interested
Counters with 10 ps timing resolution behind
tracking 10
ps 3 mm 1) Check both ps 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)
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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 105 to
  107 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.

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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 ps came from same interaction
vertex ( as central tracks)
x
tR
tL
Know position in each bunch of interacting
ps. Position-momentum correlation ? Reduce
uncertainty in incoming momenta.
t_int
t
tL
z_vtx
tR
z
Potentially valuable e.g. MSSM triplet (Higher
cross section close states)
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Its been done!
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Geometry? Want max light in delta-function ug
students at UTA Yushu Yao (Alberta)
CUT AWAY
Plates or Fibers
Rectangular Block
Tilted
Cant put MAPMT in front of 7 TeVprotons!
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
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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 pes
• Build prototype (budget? readout?)
• Test in testbeam