AMS02RATES - AMS-02 All Particle Rates Catalog

Overview

The AMS02RATES database table records the incident rates for all particle species obtained with the Alpha Magnetic Spectrometer (AMS-02) experiment on the International Space Station (ISS), 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.

The rate at which all particle species are observed within a one-second time integration period is recorded for each interval, corrected for the livetime fraction. Each integration period contains the livetime value, observed rate, and the position of the AMS-02 instrument in latitude, longitude, and radius from the Earth's center in the Earth Centered Earth Fixed (ECEF) frame of reference.

Catalog Bibcode

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

Bulletin

The AMS02RATES database table was last updated on 4 August 2026.

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 July 2026. The AMS-02 team in collaboration with the HEASARC developed the FITS file structure for these data which were created by the HEASARC from daily particle rate data provided by the AMS collaboration. The data and the database table are updated periodically to reflect additional data as they become available.

Parameters

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

Time
The date and time of the first time bin in the daily data file.

End_Time
The date and time of the last time bin in the daily data file.

Exposure
The total summed livetime of the AMS-02 instrument contained in the data file.

Rate_Mean
The mean observed rate of all particle species, corrected for livetime.

Rate_Min
The minimum observed rate of all particle species, corrected for livetime.

Rate_Max
The maximum observed rate of all particle species, corrected for livetime.

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

Contact Person

Questions regarding the AMS02RATES database table can be addressed to the HEASARC Help Desk.

Page Author: Browse Software Development Team
Last Modified: Tuesday, 04-Aug-2026 13:58:54 EDT