CHARGE SENSITIVE PREAMPLIFIER USING FIELD-EFFECT TRANSISTORS.

A general-purpose charge-sensitive Field-Effect Transistors FET preamplifier for use with high-resolution solid state radiation detectors is described. The germanium-equivalent noise linewidth of the preamplifier is less than 1.5 keV at room temperature when followed by an amplifier using single RC differentiation and integration time constants of 1 to 2 microseconds. The change in noise linewidth with input capacitance is approximately 0.07 keVpf. When used with a 4 sq cm x 0.5 cm lithium-drifted germanium detector, an energy resolution of 2.2 keV has been obtained for gamma-rays of 100 keV or less. The entire preamplifier may be operated below room temperature for improved noise performance. Author