Development of a Measurement Technique for Medium-Energy Electrons

Abstract

Development of the quadrupole mass spectrometer with the Bessel-Box type energy analyzer: Function of the energy analyzer in the partial pressure measurements ABSTRACTThe information on energy spectra of 1-100 keV electrons is expected to provide an important clue to understand heating and acceleration mechanisms of magnetospheric plasmas. However, electrons of several keV to several tens of keV are not properly verified by observations owing to the problems in the measurement techniques. This study aims to bridge this gap by applying Avalanche Photodiodes (APDs) to the detection of electrons. The internal gain of APDs enables high-resolution detection of low-energy electrons down to several keV. We have tested an APD: Type spl 3989, Hamamatsu Photonics Co. Ltd. The APD responded to 2-40 keV electrons with the fine peaks of the out put pulse height distributions. Although the experiment is limited to 40 keV, electrons up to about 60 keV are predicted to be detectable with this APD from the simulation. We also have successfully made a verification test by the sounding rocket of ISAS/JAXA targeting medium energy electrons.