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Total Cross Section, Elastic Scattering and Diffraction Dissociation at the LHC
CSC detectors for T1
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Brief description of the mechanics
Some comments on the electronics
System aspects
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January 17, 2003
Gas system and gas distribution
Cooling
HV …
TOTEM plenary meeting -Marco Bozzo
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Total Cross Section, Elastic Scattering and Diffraction Dissociation at the LHC
Cathode electrodes panels
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Honeycomb panels
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10 mm thick Nomex honeycomb
0.6 mm thick fiberglass skin (printed board)
Cathode strips
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design same for both sides of detector
Strips will cross at +/- 60 degree angle
artwork obtained with printed board technique before
gluing skin on panel
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Easy for board width up to 80-85 cm
 Only 1 company (CICOREL) for larger dimensions
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January 17, 2003
Final planarity within tolerances (+/- 0.2 mm)
Easy to shape boards
Two identical boards needed to build one detector
TOTEM plenary meeting -Marco Bozzo
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Total Cross Section, Elastic Scattering and Diffraction Dissociation at the LHC
CSC side A
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Wire support frame glued in position
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HV distribution and decoupling
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Printed board soldering pads
Thickness defines anode cathode distance  precise
machining
HV distribution to wires via decoupling resistor
At amplifier end small board with decoupling capacitor,
protection diodes and resistor
Wires soldered in position, then glued
Wire mechanical tension measured for each
wire
January 17, 2003
TOTEM plenary meeting -Marco Bozzo
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Total Cross Section, Elastic Scattering and Diffraction Dissociation at the LHC
CSC Side B
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Fiberglass frame determines exact distance
between cathode planes
No HV  slightly smaller dimensions
Provides gas tightness
Gas distribution in the two sides
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Gas distribution flow test with plexiglas detector and
smoke gave uniform gas distribution in the gap
Relative position of the two sides defined
by 2 dowels
January 17, 2003
TOTEM plenary meeting -Marco Bozzo
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Total Cross Section, Elastic Scattering and Diffraction Dissociation at the LHC
Gas distribution
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Hollow channel in the two sides
Small holes uniformly distributed
Test with smoke has proven good flow
uniformity
January 17, 2003
TOTEM plenary meeting -Marco Bozzo
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Total Cross Section, Elastic Scattering and Diffraction Dissociation at the LHC
Electronics
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1 TOTEM telescope (5 planes)
Is NOT equivalent to (from the point of view of R/O):
1 CMS chamber (6 planes)
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in TOTEM signals are generated far apart.
CMS system foresees:
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sample and store with sophisticated analog memory to solve
pile-up problems (SCA chip) and cope with trigger latency
each cluster strip hit generates 16 data words (for 8 time
samples)
Fast trigger logic gives “digital” position of cluster with
½ strip precision (an order of magnitude worst than analog
read/out)
Coincidence of anode (wire) signals to determine timing of
track
January 17, 2003
TOTEM plenary meeting -Marco Bozzo
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Total Cross Section, Elastic Scattering and Diffraction Dissociation at the LHC
Read Out data
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channel count for present layout (halftelescope):
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3135 anode wires with 3 mm pitch
5249 cathode strips of 5 mm pitch (both cathode
planes are read out)
Read out of full detector at each event
creates too many data… need data
reduction (track selection) at trigger level
Work in progress on detailed definition of
plane and telescope concentrator boards
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January 17, 2003
To reduce amount of data
Maintain information like timing, pile-up etc.
Understand which boards need to be redesigned/built
TOTEM plenary meeting -Marco Bozzo
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Total Cross Section, Elastic Scattering and Diffraction Dissociation at the LHC
GAS distribution
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Gas mixture prepared in surface
(independent gas zone)
Distribution Forward/backward in counting
room
Gas lines from counting room via the HF
cable tray
In T1 there will be 1 gas line for the 3
detectors in the half-plane (series flow)
January 17, 2003
TOTEM plenary meeting -Marco Bozzo
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Total Cross Section, Elastic Scattering and Diffraction Dissociation at the LHC
Cooling
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All the power dissipated by the electronics
inside the magnets must be “removed”
using appropriate cooling.
~200W of power dissipated by the halfplane electronics (1kW for half-telelescope)
For the number of channels considered at present
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Electronics boards installed on the support
separator in which is integrated a water
pipe for cooling.
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January 17, 2003
Tin~18-20 degrees Tout~25 degrees
TOTEM plenary meeting -Marco Bozzo
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Total Cross Section, Elastic Scattering and Diffraction Dissociation at the LHC
HV - Low Voltage
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Each CSC will have individual HV setting
capability (on, off, current and volt. protect)
Power must be adequate for largest rate
foreseen (~ 30 μA/ channel)
Low Voltage power regulation at plane level
Power …. Total power needed(?)
Use same system as CMS … (?)
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One rack on the platform on top of HF to
house VME crate(s), gas distribution, Low
and HV distribution.
No transformers! Fringe field ~500 gauss.
January 17, 2003
TOTEM plenary meeting -Marco Bozzo
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Total Cross Section, Elastic Scattering and Diffraction Dissociation at the LHC
Radiation
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All materials employed taken from the list of
tested components for radiation.
Generically (to be defined better) dose in T1
is approx two order of magnitude larger
than in the CMS CSC.
They can stand …
10 years at 1034
Our detector at most stand 1 year at 1033
January 17, 2003
TOTEM plenary meeting -Marco Bozzo
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