AMS02SPEC - AMS-02 Spectral Results Catalog

Overview

The AMS02SPEC database table records the spectral results obtained with the Alpha Magnetic Spectrometer experiment on the International Space Station (AMS-02), a cosmic ray particle detector installed in May 2011. The experiment consists of several components, which collectively measure particle species, energy, geomagnetic rigidity, or veto off-axis particles and high-energy photons. The experiment covers the energy range of ~0.1 GeV - ~2 TeV.

AMS-02 is the result of a collaboration between MIT, the University of Hawaii, CERN, NASA, the U.S. Department of Energy, and ESA. It was launched on the Space Shuttle Endeavor (STS-134) on May 16, 2011 and was installed three days later at which time science operations commenced. Operations were interrupted by in-flight servicing of the cooling pumps for the silicon tracker: servicing took place between November 2019 and January 2020, after which science operations were restored. It is anticipated to continue operations for as long as the ISS itself remains functional.

Catalog Bibcode

2021PhR...894....1A

Description

The AMS-02 experiment consists of several different detectors. Incoming on-axis particles encounter the initial Transition Radiation Detector (TRD), the upper layer Time of Flight (TOF) detector, the Silicon Tracker and Magnet, the lower layer TOF detector, the Ring Imaging Cherenkov (RICH) detector, and the Electromagnetic Calorimeter (ECAL). The Silicon Tracker and Magnet is also equipped with the Anti-Coincidence Counters (ACC) to veto off-axis particles. The two TOF layers likewise reject upward traveling particles.

The TRD separates the lightest particles from heavier by detecting transition radiation when a charged particle crosses the boundary between materials with differing dielectric constants: very light particles at several GeV energies produce this radiation, but heavier particles (protons and beyond) tend to produce far less, allowing for clean separation of electrons and positrons despite a proton-dominated cosmic ray flux.

The TOF detector consists of two planes, one above (upper) and another below (lower) the Silicon Tracker and Magnet. By measuring the flight time between the two layers, separated by 1.2 m, TOF is able to detect and reject upper-traveling signals.

The Silicon Tracker and Magnet measures the trajectory of particles and charge magnitude as they traverse the 0.15 T strength magnetic field. It also determines the rigidity of charged cosmic ray particles by measuring trajectory within the magnetic field. The magnetic field also ensures that secondary particles generated in the TRD are swept away and do not enter the ECAL.

The Ring Imaging Cherenkov detector (RICH) which measures particle velocity and charge identification for species up to Iron (Z = 26) and beyond. It detects Cherenkov radiation from particles traveling through a medium (either NaF or silica aerogel) at faster than the speed of light in the material.

The final component particles encounter is the ECAL which measures the energy of electrons, protons, and photons and fully absorbs the electromagnetic showers from particle interactions through the detector mass.

The ACC wraps around the exterior faces of the Silicon Tracker and Magnet and detects and vetoes events from particles entering in the instrument from the side.

Collectively, these sub-systems can measure the flux of a variety of particle species incident on the instrument with high precision over a very wide energy range.

References

The Alpha Magnetic Spectrometer (AMS) on the International Space Station:
Part II - Results from the First Seven Years
        Aguilar M. et al., 2021, Physics Reports, 894, 1-116
       =2021PhR...894....1A

Provenance

This database table was first ingested by the HEASARC in June 2026. The AMS-02 team in collaboration with the HEASARC developed the FITS file structure for these data. The data have been published in a series of papers (see bibliographic references) and archived in FITS format at the HEASARC. The data and the database table are updated periodically to reflect additional data as they becomes available.

Parameters

Record_ID
This parameter contains a unique identifier for the entry in the catalog.

Time
The date of the first data included in the collection. For most data sets, this is the start date of science operations (2015-10-13).

End_Time
The date of the last data included in the collection.

Species
The types of particles included in the data collection. In instances where the data contains the ratio of two species, this field contains the name of these two species followed by "ratio".

Reference
The ADS BibCode for the published paper from which the data is derived.

Energy_Min
The minimum energy considered in the spectra. The units are GeV per nucleon for nuclear species (e.g. hydrogen, helium) or GeV for particle species (e.g. electron, proton).

Energy_Max
The maximum energy considered in the spectra. The units are GeV per nucleon for nuclear species (e.g. hydrogen, helium) or GeV for particle species (e.g. electron, proton).

Rigidity_Min
The minimum geomagnetic rigidity considered in the spectra, in gigavolts (GV).

Rigidity_Max
The maximum geomagnetic rigidity considered in the spectra, in gigavolts (GV).

Data_File
The name of the FITS file containing the AMS-02 data set.

Contact Person

Questions regarding the AMS02SPEC database table can be addressed to the HEASARC Help Desk.

Page Author: Browse Software Development Team
Last Modified: Thursday, 11-Jun-2026 16:55:32 EDT