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- Wong, Winnie S., et al.
(författare)
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A pixel detector asic for dosimetry using time-over-threshold energy measurements
- 2011
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Ingår i: Radiation Measurements. - : Elsevier BV. - 1350-4487 .- 1879-0925. ; 46:12, s. 1619-1623
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Tidskriftsartikel (refereegranskat)abstract
- In this work we present the design of a chip which provides the readout of a highly segmented diode array, in which signals induced by individual X-ray photons are processed discretely. There are several benefits to this approach, including the ability to achieve a high signal to noise ratio due to the inherently low sensor capacitance, and the suppression of background noise (e.g. dark current) using an analogue threshold. The segmentation also ensures a linear behaviour even at very high dose rates. A time over threshold (ToT1) energy measurement technique provides an immediate digital value corresponding to the energy deposited onto the diode by each individual photon. Deadtime-free operation is achieved by reading out a subset of the detector segments at a time while the rest of the detector continues to process signals. This paper describes the application-specific integrated circuit (ASIC) chip which was designed to provide pre-processing of photo-induced signals in the detector and readout of the processed digital data.
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| 2. |
- Wong, Winnie S, et al.
(författare)
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Electrical measurements of a multi-mode hybrid pixel detector ASIC for radiation detection
- 2012
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Ingår i: Journal of Instrumentation. - 1748-0221. ; 7:1, s. Art. no. C01056-
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Tidskriftsartikel (refereegranskat)abstract
- We present the first electrical measurements of an application-specific integrated circuit (ASIC) to be used in a hybrid pixel detector intended for dosimetry and radiation detection. The dosimeter has three programmable modes of operation: photon counting mode, energy integration mode, and dosimetry mode. The ASIC comprises a matrix of 16 by 16 (256 total) square pixels of 220 ÎŒm pitch, providing 12.4 mm 2 of segmented active area. Each pixel can be configured to operate in one of the three radiation measurement modes, with programmable-depth counters and shift registers to tailor the data word size and optimise the readout frame-rate in a given mode. The individual energies of impinging photons are determined through programmable analogue energy threshold discrimination, time over threshold measurement, or a combination thereof. Furthermore, the dosimetry mode contains 16 digital energy thresholds and automatically sorts data into 16 corresponding energy bin registers. The chip's output is therefore pre-processed charge spectra of the radiation field. This paper discusses results from measurements taken using programmable test-pulses to inject controlled stimuli into the pixel circuits.
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