Laser and alpha particle characterization of floating-base BJT detector. Vladyslav Tyzhnevyia, Giovanni Batignanib, Luciano Bosisioc,Gian-Franco Dalla Bettaa,Giovanni Verzellesid, Nicola Zorzie a Universita di Trento and INFN Trento, Trento, Italy , b Universita di Pisa and INFN Pisa, Pisa, Italy, c Universita di Trieste and INFN Trieste, Trieste, Italy, d Universita di Modena e Reggio Emilia and INFN Trento, Reggio Emilia, Italy, e Fondazione Bruno Kessler, Trento, Italy Abstract – In this work we investigate the detection properties of existing prototypes of BJT detectors operated with floating base. We report about results of two functional tests. The charge-collection properties of BJT-detectors were evaluated by means of laser pulse. The results of functional test by a-particles emitted from radioactive Am-241 source are also presented here. Experimental results have shown that current gains of about 450 with response times in the order of 50 ms are preserved even in this non standard operation mode, in spite of a non optimized layout. BJT detector - concept BJT detector under test Single BJT pixel Emitter layout BJT detectors are able to measure different types of ionizing radiation: a-particles (!), b-particles, X- and g-photons. Matrix 20 um 32 um BJT’s active area – 1.4x1.4 mm, Emitter size– 32x32 mm Base size – 200x60 mm Substrate thickness – 600 mm, Depletion voltage ~70 V Functional test by laser Detector with floating base is low power consuming! It turns on only when particle comes. System with battery power supply can be implemented. Light calibration Detector – D400FC; Amplifier – THS4303 Electrical characterization Gummel plots (gain vs. current); leakage current; Bias voltage 10V 30V 50V 70V Gain 130 140 Functional test by a-source Am241 Single DPIX pixel Vb = 70 V Gain ~450 Am241 - source of a-particles; Ea = 5.638 MeV; Alpha surface emission rate - 1300 in 2p steradian; Matrix of DPIX pixels Single DPIX pixel Shows high gain of the detector even for 20 nAmp current; Comparably low power consumption in idle state of BJT (0.5e-6 W at 10 V); X I Pisa Meeting on Advanced Detectors May 25-29, 2009 La Biodola, Isola d'Elba (Italy)