Functionally, the Model CSA4 provides in a single width NIM module an exceptional spectroscopy amplifier. The amplifier’s excellent stability, ultra low noise, broad gain range and wide choice of shaping time constants makes it ideally suited for applications involving Germanium, Silicon, Scintillation, Gas Proportional and Surface Barrier detectors.
FCT near-Gaussian filter shaping has been refined in the Model CSA4 for improved pulse symmetry, minimum sensitivity of output amplitude to variations in detector rise time, and maximum signal to noise ratio. For a given shaping time constant, the improved pulse symmetry minimizes the pulse dwell time by tucking in the trailing skirt of the unipolar pulse shape. This allows a faster return to the baseline. The result is superior energy resolution, count rate and throughput performance. Unipolar shaping is achieved with one differentiator and two active filter integrators. The differentiator is placed early in the amplifier to insure good overload recovery. The integrators are placed late to minimize noise contribution from the gain stages. Functionally, the Model CSA4 provides in a single width NIM module a preamplifier and a shaping amplifier with four shaping times simultaneously (selectable in the range from 100ns to 8μs: four values out of seven can be ordered : 100ns, 250ns, 500ns, 1μs, 2μs, 4μs, 8μs). A power connector (D-Sub 9 female) is also available at the front panel for the power supply of external preamplifiers. A front panel adjustable pole zero can be user trimmed to match the preamp fall time constant and minimize undershoot following the first differentiator for improved overload and count rate performance.