Gamma counter module - 5 Pages

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Catalogue excerpts

SILICON PHOTODIODES FOR GAMMA RAY DETECTION First Sensor expands its detector series for ionizing radiation. The new X100-7 targets high volume gamma detection applications by combining low dark current and low capacitance silicon photodiodes with reliable and cost-efficient packaging. Recent events like the nuclear disaster in Japan have raised awareness of risks from nuclear radiation and created an additional demand for commercial as well as personal radiation detection devices. Typical products of plutonium and uranium nuclear fission processes are isotopes of Iodine l3lI and l32I, Cesium l32Cs and l37Cs, as well as Tellurium-132 and Strontium-90. While l32Te, 131I, 132I and 132I are relatively short-lived, 134Cs has a half-live of about 2 years and 137Cs as well as 90Sr even of about 30 years. Accordingly, 134Cs, 137Cs and 90Sr are the dominant radioactive isotopes regarding health impacts months and years after the nuclear disasters of Chernobyl and Fukushima. The mentioned Cesium and Iodine isotopes decay mainly emitting high energy gamma radiation between 300 and 800 keV. 90Sr emits beta radiation of 546 keV energy. Specifically, gamma radiation from Cesium-137 (662 keV) is often used to identify contamination from the Fukushima disaster. Solid state detectors provide a reliable and compact solution for radiation monitoring. Generally, solid state detectors can be divided in two groups: scintillator based and direct absorption based detectors. High performance solid state radiation detectors use the conversion of nuclear radiation into visible light by luminescence of a scintillator crystal such as CsI, LYSO or BGO. The characteristic blue or green luminescence is then detected by a very sensitive photodiode. Such a detector requires a sophisticated crystal coating to reflect all luminescence into the photodiode. The resulting advantage is a high absorption probability even for high energy radiation due to a relatively large crystal thickness. However, the crystals also result in higher manufacturing costs. A First Sensor White Paper • Author: Dr. Marc Oliver Schillgalies Published: September 1 3, 2011 • Page 1 of 5

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Absoption of Gamma radiation [%] X10- without scintillator X10- with CsI:Tl scintillator 0,3 Gamma radiation energy [keV] Fig.1. Gamma absorption characteristics of the First Sensor X10-γ detector with and without scintillator. Figure 1 illustrates this difference for the First There are several physical processes involved Sensor X10-γ detector. To increase sensitivity in the gamma photon attenuation. Compton at low gamma energies a very thin aluminized (incoherent) and Rayleigh (coherent) scattering Kapton window is used. Furthermore, the fully depletable X10-γ detectors are based on ultra- dominant...

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To reliably detect such gamma energies in current to a minimum. Low bias voltage causes a relatively small depletion zone outside of capacitance and low dark current detectors which charge carriers transit slowly by diffusion such as the X100-7 are essential. With its with transit times around 2-5µs. Using state- active area of 100 mm² it provides a large of-the-art wafer processing and high quality raw material First Sensor increased the carrier lifetime such that essentially all generated free operated already at relatively low bias voltages charge carriers are collected. to simplify circuit...

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Based on the large resonance of the market, First Sensor currently develops the next generation device: X100-7.2 with increased sensitivity both in low and high energy region. Also, custom specific options including thicker silicon, fully depletable chip designs or scintillator coupled devices are available upon request. Please contact us for full details. Several customers sucessfully integrated the X100-7 in their compact detectors for gamma radiation of Cesium isotopes to detect contamination connected with the Fukushima disaster (shown in figure 3). Reference information can be found at http://einstlab.web.fc2.com/Xdetector/detector.html...

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First Sensor AG provides cutting edge technology for sophisticated sensor applications. For full details and customization options feel free to contact us at sales.opto@first-sensor.com. SALES USA EUROPE, INTERNATIONAL SALES @ First Sensor Sr-Behre^-str. 1 s    (@y First Sensor 12459 Berlin Germany T +49 30 6399 2399 F +49 30 639923-752 sales.opto@fi rst-sensor.com Published: September 13, 2011 • Page 5 of 5

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