High Energy Resolution Hard X-Ray and Gamma-Ray Imagers Using CdTe Diode Devices

Abstract

Abstract-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 µm. 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 µm. 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.

Energy dispersive X-ray diffraction computed tomography of breast-simulating phantoms and a tissue sample

“…The signal from each pixel is processed with a charge sensitive amplifier. A two dimensional readout ASIC is used for signal processing and readout 14 15 .The detector used in this project is a 1 mm thick Schottky anode CdTe detector manufactured by ACRORAD 14 . The detector with the attached scatter collimator sits on a goniometer that allows the change of detection angle.…”

Design and performance of Soft Gamma-ray Detector onboard the Hitomi (ASTRO-H) satellite

“…A Compton camera consists of a stack of 32 layers of 0.6-mm-thick Si pixel sensors 43 followed by 8 layers of 0.75-mm-thick CdTe pixel sensors, 44,45 surrounded by 2 layers of 0.75-mm-thick CdTe pixel sensors on the four sides as shown in Fig. 2(b).…”

Modeling and simulation of Positron Emission Mammography (PEM) based on double-sided CdTe strip detectors

“…Two heads are positioned in opposing fashion in a way to move parallely, with a paddle separation of 65 mm ( figure 1 (bottom-right)). Platinum (Pt) as cathode and Aluminum (Al) as anode can be used as segmented strips [20]. The total number of channels is 2 heads × 2 lines × 180 detectors × 80 channels = 57600.…”