AMS-01 is the precursor experiment which flew on the shuttle Discovery on the STS-91 mission, from 2nd to 12th of June 1998. An historical document, the AMS-01 brochure, describes it in detail.

The AMS-01 experiment was built around a permanent cylindrical magnet built with 6,000 small NdFeB blocks. It has been the first large magnetic spectrometer ever operated in space.

The subdetectors installed on AMS-01 were:

• Silicon Detector, to measure the sign of the charge and the momentum of the charged particles
• Time of Flight, to measure the velocity of the charged particles and to provide the trigger of the experiment
• An Anticounter system, to veto particles traversing the spectrometer but crossing the magnet wall
• A threshold Cerenkov detector, to separate low velocity from high velocity particles

During the 10 days mission, AMS-01 collected nearly 80 M of triggers, which were analyzed offline after the return to ground.

The results of the analysis of these data where published on a series of highly cited papers, including a Physics Report:

1. The Alpha Magnetic Spectrometer (AMS) on the International Space Station: Part I – results from the test flight on the space shuttle. By AMS Collaboration (J. Alcaraz et al.). Physics Reports 366: 331–405, 2002. 74pp.

2. Search for anti-helium in cosmic rays. By AMS Collaboration (J. Alcaraz et al.). Feb 2000. 18pp. Phys.Lett.B 461:387-396, 1999.

3. Helium in near Earth orbit. By AMS Collaboration (J. Alcaraz et al.). Nov 2000. 10pp. Phys.Lett.B 494:193-202, 2000. 9pp.

4. Cosmic protons. By AMS Collaboration (J. Alcaraz et al.). 2000. 8pp. Phys.Lett.B 490:27-35, 2000.

5. Leptons in near earth orbit. By AMS Collaboration (J. Alcaraz et al.). 2000. 13pp. Phys.Lett.B 484:10-22, 2000, Erratum-ibid.B495:440, 2000.

6. Protons in near earth orbit. By AMS Collaboration (J. Alcaraz et al.). Feb 2000. 19pp. Phys.Lett.B 472:215-226, 2000.

7. A Study of cosmic ray secondaries induced by the Mir space station using AMS-01. By AMS-01 Collaboration (M. Aguilar et al.). Jun 2004, 18pp. Nucl.Instrum.Meth.B234:321-332, 2005.

8. Cosmic-ray positron fraction measurement from 1 to 30-GeV with AMS-01. By AMS-01 Collaboration (M. Aguilar et al.). Jun 2004, 18pp. Phys.Lett.B646:145-154, 2007.

9. Relative composition and energy spectra of light nuclei in cosmic rays: results from AMS-01. By AMS-01 Collaboration (Aguilar, M., et al.). Nov. 2010, The Astrophysical Journal 724(1), 329.

Other published papers on STS91 data analysis: