Abstract: A semiconductor radiation detector is capable of measuring a ?-ray energy spectrum at 122 keV and 662 keV and having an energy resolution of no greater than 8% with respect to 122 keV ?-rays. The semiconductor radiation detector uses a semiconductor crystal sandwiched by a cathode and an anode. The semiconductor crystal is configured from a thallium bromide single crystal in which the concentration of lead as an impurity is less than 0.1 ppm, the full width at half maximum of the (110) rocking curve in the X-ray diffraction in specimen tilting angle scan is no greater than 1.6 degrees, the full width at half maximum in specimen in-plane rotation angle scan is no greater than 3.5 degrees, and the full width at half maximum in X-ray incident angle scan is no greater than 1.3 degrees.

Abstract: The present invention provides a semiconductor radiation detector including a semiconductor crystal sandwiched between a cathode electrode and an anode electrode, and a nuclear medicine diagnosis device using the semiconductor radiation detector. The semiconductor crystal is composed of a single crystal of thallium bromide of which the concentration of lead taken as an impurity is less than 0.1 ppm.