AMS
The Alpha Magnetic Spectrometer was conceived by Sam Ting to search for dark matter, the origin of cosmic rays, and to measure antinuclei [1]. A prototype, AMS-01, was flown on the space shuttle Discovery during flight STS-91 to gather background data, test detector performance, and adjust operating parameters. The data gathered during this flight was used to search for antihelium nuclei.
The flight began on 3 June 1998 and continued for 184 hours. The shuttle altitude varied between 320 and 390 km and the latitude was between ± 51.7°. Except during the docking with the MIR space station and the descent, the z-axis of the detector was kept pointing within 45° of the zenith.
Detector Design
The AMS is the first large acceptance magnetic spectrometer to operate in outer space, which is background free, to conduct a high statistics study of cosmic particles [2]. The detector consists of a permanent magnet, tracker, time of flight hodoscopes, Cerenkov counter, and anticoincidence counters.
Magnet
The magnet was made from 1.9 tons of Nd-Fe-B in the shape of a cylindrical shell with inner diameter 1115 mm and length 800 mm. The center of the magnetic field had strength 0.14 Tesla and the analyzing power BL2 was 0.14 Tm2.
Tracker
The tracker was made of six planes of double sided silicon microstrip detectors. This device measured the rigidity by measuring the deflection and the magnitude of the charge by measuring multiple energy loss. The tracker volume consisted of less than 3% of a radiation length of material. The resolution of the tracker was 10 μm in the bending direction and 30 &mum; in the other directions.
Data Analysis
References
1. J. Alcaraz, et al. Physics Letters B 461 (1999) 387-396.
2. M. Alguilar et al. Physics Reports 366 (2002) 331-405.
