Prsentation PowerPoint

1
Third International Conference on Frontier
Science Villa Mondragone Monteporzio
Catone Physics and Astrophysics in Space

June 14, 2004

The AMS-02 Tracker
Mercedes Paniccia

University of Geneva - Switzerland
2
Third International Conference on Frontier
Science Villa Mondragone Monteporzio
Catone Physics and Astrophysics in Space

June 14, 2004

The AMS-02 detector is based on a large
acceptance (0.5 m² sr) and high sensitivity
spectrometer, composed of a super-conducting
magnet and a silicon tracking device (Tracker).

An Anti-Coincidence Counter placed inside the
inner bore of the magnet allows to reject
particles entering the Tracker laterally, outside
the main acceptance.
A Star Tracker has been added to the AMS-02
set-up to ensure accurate knowledge about the
instrument orientation, since the ISS attitude is
rather variable.
Mercedes Paniccia

University of Geneva - Switzerland
3
Third International Conference on Frontier
Science Villa Mondragone Monteporzio
Catone Physics and Astrophysics in Space

June 14, 2004

The superconducting magnet is cooled by
evaporating liquid helium and has a reservoir for
about three years of operation without refill.
Its dipolar field, normal to the aperture of
the magnet, is based on a magic ring
configuration of race track coils around a pair
of Helmholtz coils. With a field strength of 0.8
Tesla at the centre it extends the rigidity range
for charged particles up to few TV.
Mercedes Paniccia

University of Geneva - Switzerland
4
Third International Conference on Frontier
Science Villa Mondragone Monteporzio
Catone Physics and Astrophysics in Space

June 14, 2004

In order to remove the heat dissipation generated
inside the magnet by the Tracker front-end
electronics a dedicated Thermal Control System
has been developed. It is based on a
mechanically pumped two-phase loop with carbon
dioxide as working fluid.
Mercedes Paniccia

University of Geneva - Switzerland
5
Third International Conference on Frontier
Science Villa Mondragone Monteporzio
Catone Physics and Astrophysics in Space

June 14, 2004

The Tracker is built with close 2500 double sided
silicon microstrip sensors, which allow to
measure two coordinates with a single detector,
reducing thus the material budget.
The AMS-01 Tracker has been the first application
in space of the high precision silicon technology
developed for position measurements in
accelerator experiments. The high modularity, low
voltage (device is well suited to operation in space.
The 1998 shuttle test flight has proven both the
successful adaptation of the technology to the
space environment and the feasibility of large
area detectors.
Mercedes Paniccia

University of Geneva - Switzerland
6
Third International Conference on Frontier
Science Villa Mondragone Monteporzio
Catone Physics and Astrophysics in Space

June 14, 2004

The n-type, high resistivity ( 6 k?) sensors are
biased with the punch-through technique and p
blocking strips, implanted on the n-side, are
used to minimize the influence of surface charge
on the position measurement obtained from the
ohmic side.
The sensor design uses capacitive charge coupling
with implantation (readout) strip pitches of 27.5
(110) µm for the p-side and 52 (208) µm for the
n-side. The finer pitch p-side strips measure
the bending coordinate and the n-side strips
measure the orthogonal coordinate, achieving a
tracking resolution of 10 µm and of 30 µm
respectively.
The measurement of specific energy loss, dE/dx
proportional to Z², in the silicon allows
independent nuclei identification in the Tracker.
Mercedes Paniccia

University of Geneva - Switzerland
7
Third International Conference on Frontier
Science Villa Mondragone Monteporzio
Catone Physics and Astrophysics in Space

June 14, 2004

AMS-02 silicon sensors characteristics Dimensions
7.2 cm 4.1 cm Thickness
300 µm Active width
p-side 70.5 mm Strip pitch
p-side 27.5 µm Num. of
p-strips 2568 Readout
pitch p-side 110 µm Num. of
p-side readout strips 640 Active width
n-side 39.8 mm Strip pitch
n-side 104 µm Num. of
n-strips
384 Readout pitch n-side 208
µm Num. of n-side readout strips 192
Mercedes Paniccia

University of Geneva - Switzerland
8
Third International Conference on Frontier
Science Villa Mondragone Monteporzio
Catone Physics and Astrophysics in Space

June 14, 2004

The silicon sensors will be arranged in 192
ladders.
The ladder is made of variable number of silicon
sensors (from 7 to 15) with daisy chained
strips to increase the detection
surface while using a limited readout. To connect
the n-side strips a Upilex foil with copper
strips is used to transmit the signal to the
front-end electronics.
Mercedes Paniccia

University of Geneva - Switzerland
9
Third International Conference on Frontier
Science Villa Mondragone Monteporzio
Catone Physics and Astrophysics in Space

June 14, 2004

Two ladders ready to be installed
Mercedes Paniccia

University of Geneva - Switzerland
10
Third International Conference on Frontier
Science Villa Mondragone Monteporzio
Catone Physics and Astrophysics in Space

June 14, 2004

The ladders will be installed in eight layers of
1 m² each on five planes of an ultra-light
support structure.
Mercedes Paniccia

University of Geneva - Switzerland
11
Third International Conference on Frontier
Science Villa Mondragone Monteporzio
Catone Physics and Astrophysics in Space

June 14, 2004

Installing ladders on plane
Mercedes Paniccia

University of Geneva - Switzerland
12
Third International Conference on Frontier
Science Villa Mondragone Monteporzio
Catone Physics and Astrophysics in Space

June 14, 2004

The first layer assembled
Mercedes Paniccia

University of Geneva - Switzerland
13
Third International Conference on Frontier
Science Villa Mondragone Monteporzio
Catone Physics and Astrophysics in Space

June 14, 2004

Until now 80 of ladders have been produced with
the effort of several institutions involved in
the AMS-02 Tracker collaboration (University of
Geneva, INFN-Perugia, ETH-Zurich, University of
Bucarest, University of Turku, Skobeltsyen INP,
Southeast University and an industrial firm in
Italy). Three out of eight layers have been
fully equipped with ladders at University of
Geneva. The Tracker assembly is foreseen to be
completed by 2005. In the meantime an extensive
series of tests have been performed to verify the
performance of the AMS-02 silicon
Tracker results will be presented by next
speaker P. Zuccon.
Mercedes Paniccia

University of Geneva - Switzerland