Aerogel

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The Silicon Tracker of the Alpha Magnetic
Spectrometer AMS-02
C.Filipe Da Silva Costa, University of Geneva
Plan Few words about AMS The Silicon Tracker
assembly The Silicon Tracker performances Conclusi
on
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General 1
Few words about AMS
Introduction to AMS AMS is a detector for cosmic
rays and photons, which will be installed on
the International Space Station (ISS). It will
provide long duration measurements of energetic
(up to TeV) primary cosmic ray spectra and
identify particles species.

• Characteristics
• large acceptance (0.45 m² sr)
• long duration measurements
• at least 3 years
• ?high statistics

AMS is subject to space constraints, as
vibrations at space shuttle launch, temperature
variation in situ, power consumption etc
?Silicon Tracker, well adapted for these
conditions.
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General 2
Few words about AMS
Main physics studied ?Cosmic ray spectra He to
Fe from 100MeV to 1TeV ?Antimatter ?He/He
ratio, sensitivity down to 10-9 (rigidity 1-100
GV) ?Dark matter Neutralino annihilation into
?p, e,?D, ?Anomalously heavy nuclei for example
strange quark matter
General layout AMS is composed by the
following sub-detectors ?Transition Radiation
Detector ?Time Of Flight ?Ring Imaging
Cherenkov ?Electromagnetic Calorimeter ?Spectromet
er Superconducting Magnet 0.8T Silicon
Tracker
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Tracker 2
The Silicon Tracker assembly

• Tracker layout
• Arrays of silicon microstrip sensors
• ladders
• 8 layers on 5 planes
• Silicon surface 6.4 m2

Particles
Plane 1, layer 1 Plane 2, layers 23 Plane 3,
layers 45 Plane 4, layers 67 Plane 5, layer 8
B Field

• Dipolar magnetic field
• orientation.

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Ladders assembly
The Silicon Tracker assembly
First phase, all silicon sensors are glued on one
kapton foil.
?
Ladder assembly
?Double sided micro- strip sensors.
?
?
On second phase we glue reinforcement on
silicon sensors, front end electronics, ...
At the end we wrap the ladder with an EMI
Shielding.
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Ladders aligment
The Silicon Tracker assembly

• Silicon Microstrip sensor positioning
• Special care was applied to the alignment of
• silicon microstrip sensors.
• To prevent frictions, 40 µm between each
• sensor
• ?We have achieved a precision of 5 µm on
• the two directions.

y
x
?
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Performances1
The Silicon Tracker performances

• Measurement of the position resolution in
  function of the charge
• Beam Fragments from In(135 GeV/n) into a Be
  target _at_ PS (CERN)
• ?The finer pitch p-side strips and the n-side
  strips achieve a tracking resolution
• of 5-13 µm and of 20-27 µm respectively.
• The p-side measure the bending coordinate and
  n-side measure the orthogonal
• coordinate respectively to B field.

Not detailed graphic
6 ladders
Scheme of beam test setup.
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Performances2
The Silicon Tracker performances
AMS Silicon Microstrip
The measurement of specific energy loss, dE/dx
proportional to Z², in the silicon allows two
independent nuclei identifications in the Tracker.
?Each side individually n-side up to Fe
p-side up to Ar
p-side
Fe
Ar
?Combining p-side and n-side allow an
identification up to Fe with a better
separation.
n-side
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Conclusion
Conclusion
Silicon ladders show excellent performance ?dE/d
x outperform expectations ?Resolution 10 µm in
the bending direction 30 µm in the
non-bending direction Rigidity
resolution ?(R)/R1.5 at 10 GV (proton)
Resolution in function of the rigidity
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Now we are approaching to the end of the assembly
and we continue applying the same care. Six out
of eight layers are fully equipped with ladders.
The inner part of the Silcon Tracker is completed.
Conclusion
Plane 3 being stored (under Nitrogen)
Shell structure of AMS.
?AMS-02 Silicon tracker will be completed this
summer and present good performances.
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End
Conclusion
The end