High energy electron observation by Polar Patrol Balloon flight in Antarctica

We accomplished a balloon observation of the high-energy cosmic-ray electrons in 10-1000GeV to reveal the origin and the acceleration mechanism. The observation was carried out for 13 days at an average altitude of 35km by the Polar Patrol Balloon (PPB) around Antarctica in January 2004. The detector is an imaging calorimeter composed of scintillating-fiber belts and plastic scintillation counters sandwiched between lead plates. The geometrical factor is about 600cm^2sr, and the total thickness of lead absorber is 9 radiation lengths. The performance of the detector has been confirmed by a test flight at the Sanriku Balloon Center and by an accelerator beam test using the CERN-SPS (Super Proton Synchrotron at CERN). The new telemetry system using the Iridium satellite, the power system supplied by solar panels and the automatic flight level control operated successfully during the flight. We collected 5.7×10^3 events over 100GeV, and selected the electron candidates by a preliminary data analysis of the shower images. We report here an outline of both detector and observation, and the first result of the electron energy spectrum over 100GeV obtained by an electronic counter

Performance of the CALET Calorimeter by Accelerator Beam Test

We are developing the CALET (CALorimetric Electron Telescope) instrument for bserving high energy electrons and gamma rays on ISS. For confirming the CALET capability expected by simulations, we made a scale model of CALET with a size of 2/3 in thickness and had the experimental tests by using beams available in CERN. The beams used are 50GeV, 100GeV electron and 150 GeV proton. The energy resolution is sigma/E = 4.0+-0.1 percent and 2.25+-0.04 percent for 50GeV and 100GeV electrons, respectively. About 97.3 percent of protons can be rejected by shower image with Total Absorption Calorimeter, TASC, while approximately 96.8 percent of electrons were correctly identified. The performance of the scale model was also investigated by Monte Carlo simulation to compare with the results by beam tests. We confirmed good consistency between simulation and the beam test

High energy electron observation by Polar Patrol Balloon flight in Antarctica

We accomplished a balloon observation of the high-energy cosmic-ray electronsin 10-1000 GeV to reveal the origin and the acceleration mechanism. Theobservation was carried out for 15 days at an average altitude of 35 km by the PolarPatrol Balloon (PPB) around Antarctica in January ,2004. The detector is an imagingcalorimeter composed of scintillating-fiber belts and plastic scintillation counterssandwiched between lead plates. The geometrical factor is about 600 cm^2sr, and thetotal thickness of lead absorber is 9 radiation lengths. The performance of thedetector has been confirmed by a test flight at the Sanriku Balloon Center and by anaccelerator beam test using the CERN-SPS (Super Proton Synchrotron at CERN).The new telemetry system using the Iridium satellite, the power system supplied bysolar panels and the automatic flight level control operated successfully during theflight. We collected 5.7*10^3 events over 100 GeV, and selected the electron candidatesby a preliminary data analysis of the shower images. We report here an outlineof both detector and observation, and the first result of the electron energy spectrumover 100 GeV obtained by an electronic counter

Development of a high dynamic range read-out system using multiple photodiodes for the total absorption calorimeter of the CALorimetric Electron Telescope

Read-out systems using Si-PIN photodiodes and front-end circuits(FEC) were studied to measure the energy deposit with a dynamic range from 1MIP(Minimum Ionization Particle) to 106 MIPs in a BGO bar of the total absorption calorimeter (TASC) of the CALET (CALorimetric Electron Telescope) instrument. Three types of FEC were tested for the photodiode read out. Two were A225(AMP-TEK), which consists of a hybrid charge sensitive preamplifier and a shaping amplifier, and MPX-08 (NOVA), which is a charge-integrating chip. It was confirmed that the A225 has a resolution of about 0.31 fC and a maximum range of about 2 pC. It was found that the use of the A225 makes a wide range measurement with six orders of magnitude possible using three photodiodes. A new hybrid integrated circuit is being developed to measure a BGO signal with a dynamic range of seven orders using two photodiodes. This FEC consists of two preamplifiers, one for a smaller photodiode and one for a larger one. A high-gain preamplifier was developed and its performance was evaluated. The resolution is about 0.5 fC and the maximum range is more than 25 pC. This makes a dynamic range with four orders of magnitude possible using one photodiode. The outline of a read-out systems using each type of FEC and the state of the development of each system is described below

Measurement of cosmic-ray protons during Polar Patrol Balloon experiment in Antarctica

To study cosmic protons, helium and CNO components (E=100-500MeV/n) together with Hard X-rays (E=30-120keV) of auroral, solar and/or cosmic origins, the Polar Patrol Balloon no. 6 (PPB#6) was launched from Syowa Station, Antarctica on January 5,1993 by the 34th Japanese Antarctic Research Expedition. PPB#6 moved westward by 1.5 circumpolar rounds over Antarctica covering 6-13g/cm^2 atmosphereic depth and 63°-70°S geographic latitude. The cosmic radiation intensity was measured by detector system on PPB#6. This paper shows the cosmic proton intensity as a function of the geomagnetic rigidty and the proton spectra at invariant latitude of 55°, 80°, and at the cusp latitude