First Sensor announces the new X100-7 detector （X100-7 ɣ 射线探测器） for gamma radiation. It is based on First Sensor’s low dark current and low capacitance silicon photodiode （光电探测器） series. 

With its active area of 100 mm² it provides a large cross section for radiation detection. A special black epoxy encapsulant guaranties the blocking of light while maintaining small gamma ray attenuation (see Figure).

Recent events like the nuclear disaster in Japan have raised awareness of risks from nuclear radiation and created a demand for commercial as well as personal radiation detection devices. Nuclear radiation meters based on silicon solid state detectors such as the X100-7 provide a reliable and inexpensive solution for radiation monitoring.

Specifically, gamma radiation from Iodine-131 (364 keV) and Cesium-137 (662 keV) is used to identify contamination from the Fukushima disaster. High performance solid state radiation detectors （固态辐射探测器）use the conversion of nuclear radiation into visible light by a costly scintillator crystal. However, inexpensive detectors rely on direct absorption in the silicon.

Since the probability of direct absorption of such gamma energies in silicon is relatively low, large area, low capacitance and low noise detectors such as the X100-7 are essential.

First Sensor offers the X100-7 both in a ceramic SMD package as well as a ceramic 2-pin THD package in sample quantity up to high volume production. Custom specific options including thicker silicon, fully depletable chip designs or scintillator coupled devices are available upon request.