43 research outputs found
FOXSI Sounding Rocket Flights and Solar Microflare Observations
No abstract availabl
High energy resolution hard X-ray and gamma-ray imagers using CdTe diode devices
We developed CdTe double-sided strip detectors (DSDs or cross strip
detectors) and evaluated their spectral and imaging performance for hard X-rays
and gamma-rays. Though the double-sided strip configuration is suitable for
imagers with a fine position resolution and a large detection area, CdTe diode
DSDs with indium (In) anodes have yet to be realized due to the difficulty
posed by the segmented In anodes. CdTe diode devices with aluminum (Al) anodes
were recently established, followed by a CdTe device in which the Al anodes
could be segmented into strips. We developed CdTe double-sided strip devices
having Pt cathode strips and Al anode strips, and assembled prototype CdTe
DSDs. These prototypes have a strip pitch of 400 micrometer. Signals from the
strips are processed with analog ASICs (application specific integrated
circuits). We have successfully performed gamma-ray imaging spectroscopy with a
position resolution of 400 micrometer. Energy resolution of 1.8 keV (FWHM: full
width at half maximum) was obtained at 59.54 keV. Moreover, the possibility of
improved spectral performance by utilizing the energy information of both side
strips was demonstrated. We designed and fabricated a new analog ASIC, VA32TA6,
for the readout of semiconductor detectors, which is also suitable for DSDs. A
new feature of the ASIC is its internal ADC function. We confirmed this
function and good noise performance that reaches an equivalent noise charge of
110 e- under the condition of 3-4 pF input capacitance.Comment: 6 pages, 10 figures, accepted for publication in IEEE Transactions on
Nuclear Scienc
Development of a cadmium telluride pixel detector for astrophysical applications
We are developing imaging Cadmium Telluride (CdTe) pixel detectors optimized for astrophysical hard X-ray applications. Our hybrid detector consist of a CdTe crystal 1mm thick and 2cm × 2cm in area with segmented anode contacts directly bonded to a custom low-noise application specific integrated circuit (ASIC). The CdTe sensor, fabricated by ACRORAD (Okinawa, Japan), has Schottky blocking contacts on a 605 micron pitch in a 32 × 32 array, providing low leakage current and enabling readout of the anode side. The detector is bonded using epoxy-gold stud interconnects to a custom low noise, low power ASIC circuit developed by Caltech's Space Radiation Laboratory. We have achieved very good energy resolution over a wide energy range (0.62keV FWHM @ 60keV, 10.8keV FWHM @ 662keV). We observe polarization effects at room temperature, but they are suppressed if we operate the detector at or below 0°C degree. These detectors have potential application for future missions such as the International X-ray Observatory (IXO)