Title: June 6, 2001
1ATLAS Cathode Strip Chambers
- June 6, 2001
- Paul OConnor, BNL
2CSCs are the forward precision muon system of
ATLAS
IP
32 four-layer chambers 2.0 lt h lt 2.7 Z 7m,
1 lt r lt 2 m 4 gas gaps per chamber 31,000 channels
3Principle of operation
Determine muon position by interpolating the
charge on 3 to 5 adjacent strips Precision (x-)
strip pitch 5.6 mm Measure Q1, Q2, Q3 with
1501 SNR to get sx 60 mm. Second set of
y-strips measure transverse coordinate to 1
cm. Position accuracy unaffected by gas gain or
drift time variations. Accurate intercalibration
of adjacent channels essential.
S d 2.54 mm W 5.6 mm
4Chamber construction detail
5Gas Gain vs Anode-Cathode gap uniformity
- Gas Gain, to first order, not important for
Chamber precision (relative charge measurement) - Must be reasonably uniform for operational
stability - Assume need to keep gain to /- 30 -? 150 mm
gap tolerance
6Flatness of two gaps in Module Zero
Early Panel while still developing
technique Min to Max variation 6-7
One of the later panels Min to Max variation 4
7Gain measurement station
8Corresponding Gas Gain Variation
Gas Gain Variation tracks well anode-cathode gap
variation Agrees well with calculations Confiden
ce for robust operation
9CSC Electronics
- On-chamber (BNL)
- Amplifer/shaper (rad-hard custom ASIC)
- Analog memory ( )
- ADC (rad-hard COTS component)
- Off-chamber (UCI)
- Generate all control signals needed on chamber
- Sparsify raw chamber data, build event, interface
to T/DAQ - Initialization, calibration, monitoring
- Interconnect and services (BNL)
- 1000 optical links, 800 Gbits/s bandwidth
overall - LV distribution, 2.6 kA _at_ 7V at chambers (18 kW)
- HV distribution
- Liquid cooling for on-chamber electronics
- (gas system)
10Reliability
- Goal lt 0.1 data lost due to hard or soft fails
- Strategy on-detector electronics boards must be
as simple and robust as possible - Minimal parts list 10 component types
- All intelligence to reside off-chamber (SCA
Controller in ROD) - ASM boards to have no
- Configuration registers
- Programmable logic
- FIFOs
- RAM
- Counters
- State machines
- Thorough radiation test of all components
- ESD protect inputs at board and chip level
- ATLAS policy on grounding and shielding
- Extra attention to amplifier stability
- No DCS
- Minimal monitoring
11On-chamber Electronics Chain
To/from ROD
- Amplification, Sampling, digitization, and
Multiplexing into optical fiber performed on
detector. - 70 ns shaping
- 10 bit dynamic range
- 3 custom, radiation-tolerant ASICs
12Electronics Location in Faraday Cage
13Readout organization one chamber
- 864 channels per chamber
- Optical links
- 10 downlinks, 5 uplinks per chamber
14ASICs for CSC Electronics
- CHIP TYPE FOUNDRY TECHNOLOGY
- P/S analog Agilent AMOS14TB
- SCA mixed ATMEL DMILL
- MUX digital TBD TBD
- POS. VREG power ST RHBip1
15Preamp/Shaper (P/S)
- Technology Agilent 0.5 um CMOS
- Function 12-channel preamplifier and 7-pole
shaper - No. of chips required 5,120 (full scope of 64
chambers) - MPW runs 3
- Tested with full size chambers in beam
- Radiation testing preliminary ionizing test to 1
Mrad, very encouraging result - Milestones
- Beam test 09/01
- Final DR and PRR 10/01
- Production 12/01
16SCA
- Technology DMILL
- Function analog memory
- Design responsibility LARG
- No. chips required 5,120 for full scope (64
chambers) - This is the same chip used in LARG FEB
- Design was modified at our request to allow
pin-selectable MUON mode - Effectively increases the readout rate by X6
- 4 channels x 3 gains gt 12 channels
- Duty cycle 50 gt 100 per SCA
- Read clock 5 MHz gt 6.67 MHz
- Tested in MUON mode in lab, 3/01- 5/01
- LARG in control of radiation qualification,
procurement, and production testing - Production forseen for Jan. 02
17MUX
- Function data concentration between ADC and
G-link - Technology TBD
- No. of chips required TBD
- Milestones
- Start design 10/01
- MPW fab 02/02
- Final DR 10/02?
Voltage Regulator
- LHC4913 positive voltage regulator being
developed in framework of RD-49 by ST
Microelectronics Catania - Location ASM-1 and ASM-2
- Quantities required 640 ea. 5V and 3.3V (for 32
chambers)
18ASM 1 Prototype with P/S chip
19 Noise vs. capacitance
Linearity
Simulated ? Measured o
20Preamp/shaper 60Co irradiation results
Supply current
Gain
Noise
Waveform
21ASM-2 prototype with SCA chip
22ASM-2a waveforms
23ASM-2a Gain and Linearity
24ASM-2a Noise Measurement IC50 preamp/shaper
(unpulsed) into SCA on ASM-IIa board Channel 1
results displayed 24 SCA cells written and read
out Measurement repeated for 1000 cycles.
Histogram of all cells
Mean and s.d. of each cell
25CSC Off-detector electronics
optional
26ROD
- Functions
- Generate control signals and transmit to chambers
- Receive and process raw chamber data
- Assemble events and transmit to Concentrator
- Calibration and monitoring
- ROD serves 2 chambers (1920 channels, 12.8
Gbit/s) - 9U VME plus 220 mm Transition Module, 100W
- Modular design using TI DSP-based daughterboard
(GPU) - 70 x 70 mm, 3W
- gt 100 Mword/s data BW
- Component cost 300
- 12 GPUs per ROD
- Status
- GPU working prototype on hand
- ROD motherboard layout started 5/1/01
- Milestones
- Prelim. Design Review 05/01
- First prototype in hand 08/01
- Integration with ASM-2 04/02
27Low Voltage Power and Cabling
- Design for full scope (64 chambers)
- Uncertainties
- Power supply location
- Cable run details
- Local regulator characteristics
- Working assumptions
- Space for LV supplies available on UX15
floor/gallery - Use LARG-like supplies if neutron flux too high
for standard DC-DC converters - 25m run to patch panel on outside of endcap wheel
- 12 m from edge of endcap to chamber pigtail
- Total electronics power 18400 W (2630A _at_ 7V)
- Cabling 64 pairs AWG 4, 480 cm2, 1000 kg
- 100 W dissipated per cable, 6400 W total for full
scope - Fiber optic cables
- 960 fibers from USA15 (120m run)
- 90 cm2 cross section, 860 kg
28Prototype Recirculating Gas System
Design and Construction by L.Kotchenda (PNPI) and
his crew at BNL
System design similar to final Will be used in
test beams Important for long term aging tests
foreseen using X5/GIF
29Support frame, y-strip readout location, Faraday
cages
30High Rate Performance
- Overall background rate 107 Hz per chamber
- 50 charged particles, 50 neutron and g
- Charged particle background is rejected by
- Timing window around trigger (out of time)
- Or by pattern recognition of non-projective
tracks - Neutrals can deposit high charges
- 50 of neutrals above QFS
- 1 of neutrals above 6 QFS
- Neutrals produce short-range electrons usually
confined to 1-layer - But a neutral hit anywhere in chamber induces
crosstalk onto all strips by anode-cathode
crosstalk
31Beam Test Measurments
32Summary
- Chambers ready for start of production
- Two of 4 ASICs ready for production
- MUX and Voltage Regulator ASIC must be resolved
as quickly as possible - Location of power supplies must be resolved
- System test with Module 0 chamber, ASM boards
this Fall - System test of optical links and ROD next Spring
33The CSC Team
- BNL
- V. Polychronakos
- P. OConnor
- A. Kandasamy
- S. Junnarkar
- A. Gorodeev
- V. Tcherniatine
- V. Gratchev
- UCI
- A. Lankford
- D. Stoker
- M. Schernau
- S. Pier
- D. Hawkins
- N. Drego
- J. Dailing
- B. Toledano