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Cork, Ireland

SensL Technologies Ltd. | Date: 2014-05-20

The present disclosure relates to photon detectors. In particular, the present disclosure relates to high sensitivity photon detectors such as semiconductor photomultipliers. A semiconductor photomultiplier is described which comprises an array of interconnected photosensitive microcells; and at least one dark count rate (DCR) suppression element associated with the array.

Sensl Technologies Ltd. | Date: 2011-03-23

Silicon photomultiplier and readout method A silicon photomultiplier device is provided which comprises a first electrode arranged to provide a bias voltage to the device, a second electrode arranged as a ground electrode for the device, and a third electrode arranged to provide an output signal from the device using the second electrode as the output signal ground.

The present disclosure relates to a process of manufacturing a photomultiplier microcell. The process comprises providing an insulating layer over an active region; and implanting a dopant through the insulating layer to form a photosensitive diode in the active region. The insulating layer once formed is retained over the active region throughout the manufacturing process.

Du J.,University of California at Davis | Yang Y.,University of California at Davis | Bai X.,University of California at Davis | Judenhofer M.S.,University of California at Davis | And 5 more authors.
IEEE Transactions on Nuclear Science

The performance of an 8 ×8 array of 6.0 × 6.0mm2 (active area) SiPMs was evaluated for PET applications using crystal arrays with different pitch sizes (3.4, 1.5, 1.35, and 1.2 mm) and custom designed five-channel front-end readout electronics (four channels for position information and one channel for timing information). The total area of this SiPM array is 57.4 ×57.4mm2, and the pitch size is 7.2 mm. It was fabricated using enhanced blue sensitivity SiPMs (MicroFB-60035-SMT) with peak spectral sensitivity at 420 nm. The performance of the SiPM array was characterized by measuring flood histogram decoding quality, energy resolution, timing resolution and saturation at several bias voltages (from 25.0 to 30.0 V in 0.5 V intervals) and two different temperatures (5°C and 20°C). Results show that the best flood histogram was obtained at a bias voltage of 28.0 V and 5°C and an array of polished LSO crystals with a pitch as small as 1.2 mm can be resolved. No saturation was observed up to a bias voltage of 29.5 V during the experiments, due to adequate light sharing between SiPMs. Energy resolution and timing resolution at 5°C ranged from 12.7 ± 0.8% to 14.6 ± 1.4% and 1.58 ± 0.13ns to 2.50 ±0.44ns, for crystal array pitch sizes of 3.4 and 1.2 mm, respectively. Superior flood histogram quality, energy resolution and timing resolution were obtained with larger crystal array pitch sizes and at lower temperature. Based on our findings, we conclude that this large-area SiPM array can serve as a suitable photodetector for high-resolution small-animal PET or dedicated human brain PET scanners. © 1963-2012 IEEE. Source

Du J.,University of California at Davis | Schmall J.P.,University of California at Davis | Yang Y.,University of California at Davis | Di K.,University of California at Davis | And 5 more authors.
Medical Physics

Purpose: The MatrixSL-9-30035-OEM (Matrix9) from SensL is a large-area silicon photomultiplier (SiPM) photodetector module consisting of a 3?3 array of 4?4 element SiPM arrays (total of 144 SiPM pixels) and incorporates SensLs front-end electronics board and coincidence board. Each SiPM pixel measures 3.16?3.16 mm2 and the total size of the detector head is 47.8?46.3 mm2. Using 8?8 polished LSO/LYSO arrays (pitch 1.5 mm) the performance of this detector system (SiPM array and readout electronics) was evaluated with a view for its eventual use in small-animal positron emission tomography (PET). Methods: Measurements of noise, signal, signal-to-noise ratio, energy resolution, flood histogram quality, timing resolution, and array trigger error were obtained at different bias voltages (28.032.5 V in 0.5 V intervals) and at different temperatures (5 ?C25 ?C in 5 ?C degree steps) to find the optimal operating conditions. Results: The best measured signal-to-noise ratio and flood histogram quality for 511 keV gamma photons were obtained at a bias voltage of 30.0 V and a temperature of 5 ?C. The energy resolution and timing resolution under these conditions were 14.2% ± 0.1% and 4.2 ± 0.1 ns, respectively. The flood histograms show that all the crystals in the 1.5 mm pitch LSO array can be clearly identified and that smaller crystal pitches can also be resolved. Flood histogram quality was also calculated using different center of gravity based positioning algorithms. Improved and more robust results were achieved using the local 9 pixels for positioning along with an energy offset calibration. To evaluate the front-end detector readout, and multiplexing efficiency, an array trigger error metric is introduced and measured at different lower energy thresholds. Using a lower energy threshold greater than 150 keV effectively eliminates any mispositioning between SiPM arrays. Conclusions: In summary, the Matrix9 detector system can resolve high-resolution scintillator arrays common in small-animal PET with adequate energy resolution and timing resolution over a large detector area. The modular design of the Matrix9 detector allows it to be used as a building block for simple, low channel-count, yet high performance, small animal PET or PET/MRI systems. © 2015 American Association of Physicists in Medicine. Source

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