National Aeronautics and Space Administration

CALET

The CALorimetric Electron Telescope (CALET) is a Japan-led international mission funded by the Japanese Space Agency (JAXA) in collaboration with the Italian Space Agency (ASI), NASA and several universities in Japan, Italy, and the United States. The instrument was launched on August 19, 2015 by a Japanese carrier, H2 Transfer Vehicle (HTV), and robotically installed on the Japanese Experiment Module-Exposed Facility (JEM-EF) on the International Space Station (ISS). First events were recorded in October 2015.

Mission Characteristics

Lifetime

Energy Range

Special Features

Payload

• The CALET Calorimeter (CCAL) measures the cosmic-ray total electron spectrum from energy ~1 GeV up to Tev region. It’s components are:
  • Charge Detector (CHD), a plastic scintillator hodoscope for absolute charge measurement. It contains two orthogonal layers. Each layer contains of 14 plastic scintillator paddles measuring 45 x 3.2 x 1 cm. It can detect charge between 1 and ∼40 Z
  • IMaging Calorimeter (IMC), a sampling calorimeter. It consists of 16 kayers of scintillating fibers (SciFi) with 1 mm² cross section, with alternating layers arranged orthogonally. It also includes interspacing thin tungsten absorbers, and tracks early show profile through the first 3 X₀
  • Total AbSorption Calorimeter (TASC), a thick lead tungstate (PWO) hodoscope with 12 alternating layers of X-Y arranged logs, with a total shower depth of 27 X₀
• The CALET Gamma Ray Burst Monitor (CGBM) is sensitive from the soft X ray (∼7 keV) to gamma ray (∼20 MeV) energy range.
  • Hard X-ray Monitor (HXR; two identical units)
    • 7 – 1000 keV
    • Lanthanum bromide (LaBr₃(Ce)) scintillation detector
    • 61 mm diameter with 12.7 mm thick detector
    • ∼ 3 sr field of view
  • Soft Gamma-ray Monitor (SGM; one unit)
    • 100 keV – 20 MeV
    • Bismuth germanate (BGO) scintillation detector
    • 102 mm diameter with 76 mm thick detector
    • ∼ 8 sr field of view

In addition to the primary instruments, there are two other main components. The Advance Stellar Compass (ASC) to determine the attitude with arcseconds precision. The Mission Data Controller (MDC) capture and format the data from the instruments, and sends the telemetry to the NASA ground station.

Science Highlights

• High precision measurements of cosmic-ray electron and proton spectrum up to several TeV
• Measurements and monitoring of galactic diffuse gamma rays
• Set limits on hard X-ray and gamma-ray emissions from gravitional wave event GW151226

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