Noise considerations of the Beetle amplifier used with long silicon strip detectors

An attempt is made to predict the thermal noise and the shot noise for silicon strip detectors connected to the Beetle preamplifier from basic electronic noise principles. The calibration pulse shapes are used to determine the frequency dependant gain function of the Beetle. The calculated noise values are compared with measurements on the prototype ladders. In addition the signal propagation in the very long ladders is studied using a spice simulation. From this the effect of the thermal noise originating from the ohmic resistors of the detector readout strips is estimated.