AMS02 Tracker Alignment System RWTH Aachen

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AMS02 Tracker Alignment SystemRWTH Aachen

• February 9, 2005
• CERN
• W. Wallraff

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TAS components
TAS properties Light weight (3 kg) Low power (lt
0.1 W) Fast data taking (20s) Highly accurate (lt
5µm)
Low power laser diodes 100 nJ pulses are
sufficent for observing signals in 8 successive
layer
Antireflective coating mandatory nSi 3
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Laser Electronics

• The Laser Electronics is located in M-Crate
• It consists of 6 boards
• 5 LDDR (laser diode driver)
• 1 LCTL (trigger distribution)
• Each LDDR drives two laser diodes
• The Laser system is controlled by two USCMs
• There are 3 more modules in M-Crate
• 1 x GPS module
• 2 x ASTE

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LDDR Board

• Power consumption of LDDR
• digital part 5V_at_ 170 mA
• analogue part 5V_at_ from almost 0 to 200 mA

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Block Diagram of LDDR
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details on optics see TAS_sysSaf_v2.0 and my JSC
10-04 report
same as shown at the 2004 JSC meeting
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LFCR in detail (explanations in the report)
Cu Ni12 Zn24 (Ns 6512)
AlSi1MgMn - AW 6082
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1 of 40 fibre connections Mounted on the rims of
the outer tracker flanges
TAS components are extremely light weight
TAS hardware (example)
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IR feed lines
LBBX in tracker plate 6 cut-out (baignoire)
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Baignoires for LBBXs
on Tracker Outer Plate
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Center ladder moveable support (GVA Jan. 05)
Check of center ladder displacements with respect
to lines observed by adjacent ladders recording
laser hits 200µm reproducible (?) steps in y and
in z (Geneva Mech. Workshop)
y
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Laser source positioner
5-axis high precision (10µm) mechanical laser
source positioner
All 4 AR areas can be reached
2 parallel beams offset in y and in x will be
measured simultaneously later this week (if the
DAQ computer can be made working)
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Checking laser beam position
AR sensors are highly transparent to 1082nm
laser beams
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TAS data taking at Geneva University (2003) using
flight hardware
Si Ladders
antireflective areas

• Laser beam(s)
• 1082 nm
• 0.5 mm diam
• 0.5 mrad div.

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ACC panel overall dimensions
1mm step size
8mm
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Position Calibration
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ARwafer
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Diffraction measures z
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Current status 1

• Laser DAQ (all strips, 3 ladders, raw mode) runs
  smoothly at 200 Hz.
• The data shown today are obtained in much less
  than a second.
• Limitations have not been investigated so far.
• The laser intensity may be varied (electrically)
  by a factor of 10 (20dB). If larger pulse to
  pulse intensity fluctuations can be accepted the
  intensity may be varied by 30 dB.
• Baseline stability, saturation and non linearity
  need to be studied, especially if the z
  information shall be derived from the diffraction
  patterns observed.

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TAS summary
summary
5 µm precision is easy

• innovative nonintrusive alignment control method
• Adopted after the AMS-01 success by the largest
  Si detector on ground CMS at the CERN LHC
• based on Swiss high precision Si-Technology
• (10nm thickness control of AR deposits)
• Laser intensity very low, no danger for
  astronauts
• engineering versions of flight hardware in hand
  and tested
• flight hardware has been ordered 12-2004

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TAS system safety status

• Description v2.0 30-Nov-2004
• TAS_sysSaf_v2.0 (MS-word ,169kB), sent to
  Porter et al. on Dec 5th 2004
• Document overview
• 1 The introduction describes the purpose and
  the basic operation principles of TAS
• 2 The TAS system components and their
  layout are introduced
• 2.0 System geometry
• 2.1 Laser beam parameters
• 2.2 Laser beam port box LBBX
• 2.3 Fibres LFIB
• 2.4 Laser fibre coupler LFCR
• 2.4.1 Laser diode
• 2.4.2 diode fibre coupling optics
• 2.4.3 fibre splitter
• 2.4.4 optical output connectors
• 2.4.5 electrical input connectors

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Document overview cont.

• 3 The IR radiation levels
• 3.1 TAS Laser power basics
• 3.2 Maximum Permissible Exposure Data
  (ANSI Z136.1)
• 3.3 Summary MPE
• 4 Figures
• 5 Appendices
• 5.1 KSC authorization for AMS-01 TAS Laser
  utilization (1998)
• 5.2 AMS-01 TAS Laser safety document (1997)