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FP420Cerenkov Intro


between beam pipes, not roman pots (Micro talk) ... of a photocathode and a series of dynodes in an evacuated glass enclosure. ... – PowerPoint PPT presentation

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Title: FP420Cerenkov Intro

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
  • FP420 Forward Protons 420m downstream of CMS
  • 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
  • High precision movement (microns),
    reproducibility, fail-safe.

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
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

BTeV pixel CMS pixel current users of area A
MT6-B ... another area behind
Some views of present A1 set-up (Sep 8 2005)
Side view, beam from L
2 views of exit
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)
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

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)
Know position in each bunch of interacting
ps. Position-momentum correlation ? Reduce
uncertainty in incoming momenta.
Potentially valuable e.g. MSSM triplet (Higher
cross section close states)
Its been done!
Geometry? Want max light in delta-function ug
students at UTA Yushu Yao (Alberta)
Plates or Fibers
Rectangular Block
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
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
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