|
Summary of Research Projects (Supports in 2004
Fiscal Year)
| Subjects |
Development of a measurement technique for 3-100 keV
electrons using Avalanche Photodiode |
| Representative researcher |
Institute of Space and Astronautical Science,Japan Aerospace Exploration
Agency
Toshifumi MUKAI |
| The information on energy
spectra of 1-100keV electrons is expected to provide an important
clue to understand heating and acceleration mechanisms of magnetospheric
plasmas. However, there have been very few reliable data of
electrons of several keV to several tens of keV, due to technical
problems. This study aims to bridge this 'gap' by applying
Avalanche Photodiodes (APDs) to the detection of electrons.
The APD is a kind of p-n junction semiconductor with an internal
avalanche gain. We have tested the performace of APDs (Type
spl3989 and Z7966, Hamamatsu Photonics K.K.) in the electron
measurements up to 40keV. The spl3989 responded to 2-40keV
electrons with clear peaks in the output pulse height distributions
and their good linearity to the electron energy. The energy
resolution is lower than 1keV for 2-20keV electrons and 5keV
for 40keV. In order to demonstrate its usefulness in space,
an instrument has been developed to measure auroral precipitating
electrons on the sounding rocket S-310-35. The rocket was launched
from Andoya, Nolway on 13 December 2004. The system worked
well, and the energy spectra of 3.5-65 keV electrons were measured
at low altitudes (90-140km) in the auroral ionosphere. The
existence of a nonthermal tail in the energy spectra was clearly
revealed with better accuracy than ever achieved. |
|
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