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    Time of flight measurements based on FPGA and SiPMs for PET–MR

    A. Aguilar, R. García-Olcina, P. A. Martínez, J. Martos, J. Soret, J. Torres, J.M. Benlloch, A.J. González, F. Sánchez

    (2014). Article

    Nuclear Inst. and Methods in Physics Research, A.. Num.734

    Coincidence time measurements with SiPMs have shown to be suitable for PET/MR systems. The present study is based on 3×3 mm2 SiPMs, LSO crystals and a conditioning signal electronic circuit. A Constant Fraction Discriminator (CFD) is used to digitalize the signals and a TDC FPGA-implemented is employed for fine time measurements. TDC capability allows processing the arrival of multiple events simultaneously, measuring times under 100 ps. The complete set-up for time measurements results on a resolution of 892±41 ps for a pair of detectors. The details of such implementation are exposed and the trade-offs of each configuration are discussed.

    DOI: 10.1016/j.nima.2013.09.008
    ISSN: 0168-9002
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    High resolution Time of Flight determination based on reconfigurable logic devices for future PET/MR systems

    J. Torres, A. Aguilar, R. García-Olcina, J. Martos, J. Soret, J.M. Benlloch, A.J. González, F. Sánchez

    (2013). Article

    NIMA. Num.702

    This contribution shows how to perform Time of Flight (TOF) measurements in PET systems using low-cost Field Programmable Gate Array (FPGA) devices with a resolution better of 100 ps. This is achieved with a proper management of the FPGA internal resources and with an extremely careful device calibration process including both temperature and voltage compensation. Preliminary results are reported.

    DOI: 10.1016/j.nima.2012.08.034
    ISSN: 0168-9002
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    Novel Wireless Sensor System for Dynamic Characterization of Borehole Heat Exchangers

    Martos, J.; Montero, Á.; Torres, J.; Soret, J.; Martínez, G.; García-Olcina, R.

    (2011). Article

    Sensors. Num.11(7)

    The design and field test of a novel sensor system based in autonomous wireless sensors to measure the temperature of the heat transfer fluid along a borehole heat exchanger (BHE) is presented. The system, by means of two specials valves, inserts and extracts miniaturized wireless sensors inside the pipes of the borehole, which are carried by the thermal fluid. Each sensor is embedded in a small sphere of just 25 mm diameter and 8 gr weight, containing a transceiver, a microcontroller, a temperature sensor and a power supply. A wireless data processing unit transmits to the sensors the acquisition configuration before the measurements, and also downloads the temperature data measured by the...

    The design and field test of a novel sensor system based in autonomous wireless sensors to measure the temperature of the heat transfer fluid along a borehole heat exchanger (BHE) is presented. The system, by means of two specials valves, inserts and extracts miniaturized wireless sensors inside the pipes of the borehole, which are carried by the thermal fluid. Each sensor is embedded in a small sphere of just 25 mm diameter and 8 gr weight, containing a transceiver, a microcontroller, a temperature sensor and a power supply. A wireless data processing unit transmits to the sensors the acquisition configuration before the measurements, and also downloads the temperature data measured by the sensor along its way through the BHE U-tube. This sensor system is intended to improve the conventional thermal response test (TRT) and it allows the collection of information about the thermal characteristics of the geological structure of subsurface and its influence in borehole thermal behaviour, which in turn, facilitates the implementation of TRTs in a more cost-effective and reliable way.

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    DOI: 10.3390/s110707082
    ISSN: 1424-8220