A study of the timing properties of position-sensitive avalanche photodiodes

Wu, Yue; Ng, Thomas S.C.; Yang, Yongfeng; Shah, K.S.; Farrell, R.; Cherry, Simon R.

doi:10.1088/0031-9155/54/17/006

Cited by 17 publications

(21 citation statements)

References 15 publications

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“…The PS-SSPM timing results, from both the 10 mm PS-SSPM and 5 mm PS-SSPM designs studied in this work, share many similarities with timing results obtained with PS-APDs [14], [15]. The timing shift across the surface of the PS-SSPM sensing area is of similar magnitude to that measured with PS-APDs, though it is important to note the device area; in terms of distance from center to corner the 5 mm PS-SSPM has a shift of 7.1 ns/mm, the 10 mm PS-SSPM a shift of 2.9 ns/mm, and a 14 mm PS-APD for comparison has a shift of 2.5 ns/mm.…”

Section: Discussionsupporting

confidence: 57%

“…2, where the cathode channel was fed directly into an Ortec 579 fast filter amplifier and the four corner anode channels were amplified by Cremat CR-113 preamplifiers before further amplification and shaping with a CAEN n568B spectroscopy amplifier (shaping time 100 ns). The setup for time stamp generation was similar to the publication of Wu 2009 [14], using an Ortec 584 for constant fraction (CF) or leading edge (LE) time pick off and an Ortec 416A gate and delay generator to adjust the trigger delay for the digitization using a simultaneously sampled DAQ board (UEI, Inc., Walpole, MA) [17]. For full pulse digitization of the raw detector signals a 2.4 GHz bandwidth oscilloscope (Tectronics, DPO 7254) with 40 Gs/sec sampling rate was used.…”

Section: Methodsmentioning

confidence: 99%

“…Much of this work follows, and in some cases builds upon, our knowledge of position-sensitive avalanche photodiode (PS-APD) signal properties [14], [15]. As we will show, PS-SSPMs share the cathode signal position dependent timing shift found in PS-APD designs but with the addition of a significant position-dependent rise time shift in the four corner anode signals following a charge sensitive preamplifier.…”

Section: Introductionmentioning

confidence: 97%

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A Study of Position-Sensitive Solid-State Photomultiplier Signal Properties

Schmall

Judenhofer

et al. 2014

IEEE Trans. Nucl. Sci.

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We present an analysis of the signal properties of a position-sensitive solid-state photomultiplier (PS-SSPM) that has an integrated resistive network for position sensing. Attractive features of PS-SSPMs are their large area and ability to resolve small scintillator crystals. However, the large area leads to a high detector capacitance, and in order to achieve high spatial resolution a large network resistor value is required. These inevitably create a low-pass filter that drastically slows what would be a fast micro-cell discharge pulse. Significant changes in the signal shape of the PS-SSPM cathode output as a function of position are observed, which result in a position-dependent time delay when using traditional time pick-off methods such as leading edge discrimination and constant fraction discrimination. The timing resolution and time delay, as a function of position, were characterized for two different PS-SSPM designs, a continuous 10 mm × 10 mm PS-SSPM and a tiled 2 × 2 array of 5 mm × 5 mm PS-SSPMs. After time delay correction, the block timing resolution, measured with a 6 × 6 array of 1.3 × 1.3 × 20 mm3 LSO crystals, was 8.6 ns and 8.5 ns, with the 10 mm PS-SSPM and 5 mm PS-SSPM respectively. The effect of crystal size on timing resolution was also studied, and contrary to expectation, a small improvement was measured when reducing the crystal size from 1.3 mm to 0.5 mm. Digital timing methods were studied and showed great promise for allowing accurate timing by implementation of a leading edge time pick-off. Position-dependent changes in signal shape on the anode side also are present, which complicates peak height data acquisition methods used for positioning. We studied the effect of trigger position on signal amplitude, flood histogram quality, and depth-of-interaction resolution in a dual-ended readout detector configuration. We conclude that detector timing and positioning can be significantly improved by implementation of digital timing methods and by accounting for changes in the shape of the signals from PS-SSPMs.

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Section: Discussionsupporting

confidence: 57%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

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A Study of Position-Sensitive Solid-State Photomultiplier Signal Properties

Schmall

Judenhofer

et al. 2014

IEEE Trans. Nucl. Sci.

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“…Timing resolution was compared using the different capacitor values. For each capacitor value, the timing resolution was quantified in several ways by post processing of the data using a 200 keV lower energy threshold, by applying an energy window of 400 - 650 keV, and with and without a crystal timing shift calibration [18]. The timing shift calibration corrects for the position- dependent offsets in pulse arrival time due to the resistive readout of the PS-SSPM.…”

Section: Methodsmentioning

confidence: 99%

A Simple Capacitive Charge-Division Readout for Position-Sensitive Solid-State Photomultiplier Arrays

Schmall

Yang

et al. 2013

IEEE Trans. Nucl. Sci.

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A capacitive charge-division readout method for reading out a 2 × 2 array of 5 mm × 5 mm position-sensitive solid-state photomultipliers (PS-SSPM) was designed and evaluated. Using this analog multiplexing method, the 20 signals (16 position, 4 timing) from the PS-SSPM array are reduced to 5 signals (4 position, 1 timing), allowing the PS-SSPM array to be treated as an individual large-area PS-SSPM module. A global positioning approach can now be used, instead of individual positioning for each PS-SSPM in the array, ensuring that the entire light signal is utilized. The signal-to-noise ratio (SNR) and flood histogram quality at different bias voltages (27.5 V to 32.0 V at 0.5 V intervals) and a fixed temperature of 0 °C were evaluated by coupling a 6 × 6 array of 1.3 mm × 1.3 mm × 20 mm polished LSO crystals to the center of the PS-SSPM array. The timing resolution was measured at a fixed bias voltage of 31.0 V and a fixed temperature of 0 °C. All the measurements were evaluated and compared using capacitors with different values and tolerances. Capacitor values ranged from 0.051 nf to 10 nf, and the capacitance tolerance ranged from 1% to 20%. The results show that better performance was achieved using capacitors with smaller values and better capacitance tolerance. Using 0.2 nf capacitors, the SNR, energy resolution and timing resolution were 24.3, 18.2% and 8.8 ns at a bias voltage 31.0 V, respectively. The flood histogram quality was also evaluated by using a 10 × 10 array of 1 mm × 1 mm × 10 mm polished LSO crystals and a 10 × 10 array of 0.7 mm × 0.7 mm × 20 mm unpolished LSO crystals to determine the smallest crystal size resolvable. These studies showed that the high spatial resolution of the PS-SSPM was preserved allowing for 0.7 mm crystals to be identified. These results show that the capacitive charge-division analog signal processing method can significantly reduce the number of electronic channels, from 20 to 5, while retaining the excellent performance of the detector.

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“…Lastly, one pincushion distorted flood was tested (Wu et al, 2009), shown in Figure 3-22. Since there is only one of these floods no statistical data is available and this section merely serves as a proof of concept for floods with similar distortions.…”

Section: Pin Cushion Distortion Floodsmentioning

confidence: 99%

An algorithm for automatic crystal identification in pixelated scintillation detectors using thin plate splines and Gaussian mixture models

2016

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Positron emission tomography (PET) is a non-invasive imaging technique which utilizes positronemitting radiopharmaceuticals (PERs) to characterize biological processes in tissues of interest. A PET scanner is usually composed of multiple scintillation crystal detectors placed in a ring so as to capture coincident photons from a position annihilation. These detectors require a crystal lookup table (CLUT) to map the detector response to the crystal of interaction. These CLUTs must be accurate, lest events get mapped to the wrong crystal of interaction degrading the final image quality. This work describes an automated algorithm, for CLUT generation, focused around Gaussian Mixture Models (GMM) with Thin Plate Splines (TPS). The algorithm was tested with flood image data collected from 16 detectors. The method maintained at least 99.8% accuracy across all tests. This method is considerably faster than manual techniques and can be adapted to different detector configurations.iii Acknowledgements

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A study of the timing properties of position-sensitive avalanche photodiodes

Cited by 17 publications

References 15 publications

A Study of Position-Sensitive Solid-State Photomultiplier Signal Properties

A Study of Position-Sensitive Solid-State Photomultiplier Signal Properties

A Simple Capacitive Charge-Division Readout for Position-Sensitive Solid-State Photomultiplier Arrays

An algorithm for automatic crystal identification in pixelated scintillation detectors using thin plate splines and Gaussian mixture models

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