Front-End ASIC for a Liquid Argon TPC De Geronimo, G; D'Andragora, A; Shaorui Li ...
IEEE transactions on nuclear science,
06/2011, Letnik:
58, Številka:
3
Journal Article
Recenzirano
We present a front-end application-specific integrated circuit (ASIC) for a wire based time-projection-chamber (TPC) operating in liquid Argon (LAr). The LAr TPC will be used for long baseline ...neutrino oscillation experiments. The ASIC must provide a low-noise readout of the signals induced on the TPC wires, digitization of those signals at 2 MSamples/s, compression, buffering and multiplexing. A resolution of better than 1000 rms electrons at 200 pF input capacitance for an input range of 300 fC is required, along with low power and operation in LAr (at 87 K). We include the characterization of a commercial technology for operation in the cryogenic environment and the first experimental results on the analog front end. The results demonstrate that complementary metal-oxide semiconductor transistors have lower noise and much improved dc characteristics at LAr temperature. Finally, we introduce the concept of "1/f equivalent" to model the low-frequency component of the noise spectral density, for use in the input metal-oxide semiconductor field-effect transistor optimization.
Anesthesia is currently required for positron emission tomography (PET) studies of the animal brain in order to eliminate motion artifacts. However, anesthesia profoundly affects the neurological ...state of the animal, complicating the interpretation of PET data. Furthermore, it precludes the use of PET to study the brain during normal behavior. The rat conscious animal PET tomograph (RatCAP) is designed to eliminate the need for anesthesia in rat brain studies. It is a miniaturized full-ring PET scanner that is attached directly to the head, imaging nearly the entire brain. RatCAP utilizes arrays of 2 mm /spl times/ 2 mm LSO crystals coupled to matching avalanche photodiode arrays, which are in turn read out by full custom integrated circuits. Principal challenges have been addressed considering the physical constraints on size, weight, and heat generation in addition to the usual requirements of small-animal PET, such as high spatial resolution in the presence of parallax error. A partial prototype has been constructed and preliminary measurements and optimization completed. Realistic Monte Carlo simulations have also been carried out to optimize system performance, which is predicted to be competitive with existing microPET systems.
We are developing a scanner that will allow simultaneous acquisition of high resolution anatomical data using magnetic resonance imaging (MRI) and quantitative physiological data using positron ...emission tomography (PET). The approach is based on the technology used for the RatCAP conscious small animal PET tomograph which utilizes block detectors consisting of pixelated arrays of LSO crystals read out with matching arrays of avalanche photodiodes and a custom-designed ASIC. The version of this detector used for simultaneous PET/MRI imaging will be constructed out of all nonmagnetic materials and will be situated inside the MRI field. We have demonstrated that the PET detector and its electronics can be operated inside the MRI, and have obtained MRI images with various detector components located inside the MRI field. The MRI images show minimal distortion in this configuration even where some components still contain traces of certain magnetic materials. We plan to improve on the image quality in the future using completely non-magnetic components and by tuning the MRI pulse sequences. The combined result will be a highly compact, low mass PET scanner that can operate inside an MRI magnet without distorting the MRI image, and can be retrofitted into existing MRI instruments.
In thick fully depleted CCDs charge carrier transport from the back window to the gates is accompanied by charge diffusion. Lateral diffusion smooths out density variations of the incoming photon ...flux by redistributing charges spatially. This creates short range positive correlations in recorded amplitudes. Pixel-to-pixel amplitude variations can also be caused by pixel size and quantum efficiency variations. Pixel size variations result in short range negative correlations. Our study shows that the characteristic diffusion width can be extracted from flat field data.
The study was performed on fully depleted, thick CCDs produced in a technology study for the Large Synoptic Survey Telescope (LSST). Data were taken in the laboratory at bias voltages between −5 and −40
V. To increase statistical accuracy, images taken in identical conditions were co-added after base line subtraction and master files were produced. A flat field image simulator was developed for statistical comparison of simulated and measured images.
Results on diffusion, pixel response variations, data features, analysis and modeling techniques are presented and discussed.
A time projection chamber for experiments with the laser electron gamma source is being developed. It is composed of a can and a single-ended, dual-stage gas electron multiplier, with associated ...anode plane pixellated into about 8000 pads. The front-end electronics must provide energy, timing, and address information from those pads involved in measuring each track. For center of gravity determination this information must be sampled from the above-threshold pad and from the two adjacent ones. An efficient scheme for readout of the /spl ap/8000 front-end channels between each measurement cycle is also required. A 32-channel front-end application-specific integrated circuit has been developed to serve this detector. Fabricated in 0.25 /spl mu/m CMOS technology, it dissipates 41 mW. Each channel implements a low noise charge preamplifier with continuous reset of new concept, shaping amplifier with bandgap referenced baseline stabilizer, single threshold discriminator, dual-phase peak detector, timing detector, and logic for neighbor enabling. The readout process is based on token passing and flag.
Front-end electronics for imaging detectors De Geronimo, G; O'Connor, P; Radeka, V ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
2001, Letnik:
471, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Front-end electronics for imaging detectors with large numbers of pixels (10
5–10
7) is reviewed. The noise limits as a function of detector capacitance and power dissipation are presented for CMOS ...technology. Active matrix flat panel imagers (AMFPIs) are discussed and their potential noise performance is illustrated.
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