We are developing the CALorimetric Electron Telescope, CALET, mission for the Japanese Experiment Module
Exposed Facility, JEM-EF, of the International Space Station. Major scientific objectives are to search for the nearby
cosmic ray sources and dark matter by carrying out a precise measurement of the electrons in 1 GeV - 20 TeV and
gamma rays in 20 MeV - several 10 TeV. CALET has a unique capability to observe electrons and gamma rays over 1
TeV since the hadron rejection power can be larger than 105 and the energy resolution better than a few % over 100 GeV.
The detector consists of an imaging calorimeter with scintillating fibers and tungsten plates and a total absorption
calorimeter with BGO scintillators. CALET has also a capability to measure cosmic ray H, He and heavy ionsi up to
1000 TeV. It also will have a function to monitor solar activity and gamma ray transients. The phase A study has
started on a schedule of launch in 2013 by H-II Transfer Vehicle (HTV) for 5 year observation.
We describe a new balloon-borne cosmic-electron telescope that incorporates a trigger system and an imaging calorimeter. It is designed to observe high-energy electrons with an energy greater than 10 GeV. The rejection of the background protons is performed by using the trigger system in real time and the off-line analysis of three-dimensional shower profiles observed in the imaging calorimeter. The calorimeter consists of scintillating-fiber belts, emulsion plates and lead plates (approximately 8r.1.thick in total). In order to observe the direction of showers, two belts in each depth are set at right angles with each other. Image intensifier is used to amplify the number of photons from scintillating fibers, and CCD camera is attached at the output window of the image intensifier. The telescope was launched at Sanriku Balloon Center, and it was flown for 12 hours at the level altitude. By preliminary analysis, we observed about 700 electrons over 10 GeV under 4g cm-2 of average residual atmosphere. The flux of electrons is consistent with previous observations.
A scintillating fiber sampling calorimeter telescope (SSCT) intended to be operated onboard a satellite for cosmic gamma-ray observation in the range from 200 MeV to 200 GeV is presented. SSCT consists of a target part and a main part that includes a calorimeter with imaging capability, which are separated by a distance of 60-70 cm. A gamma ray enters the target and is converted into a pair of electrons which in turn develops into an electron-photon cascade that is observed in the main part. The gamma-ray direction is measured by pointing the energy-weighted centers observed in the two parts. The shower particle are detected using 2 mm square fibers which are bundled into a 2 mm thick flat belt. A pair of belts crossing at a right angle is inserted between lead plates. Experimental results show that the energy resolution of the calorimeter is 20 percent/sq root E(GeV) below a few GeV. The angular resolution is 1.6 deg at 1 GeV and 0.34 deg at 10 GeV.