An Innovative Analog Circuit to Retrieve Energy Information From Signals of Deeply Saturated Preamplifiers Connected to Semiconductor Detectors

Abstract

In nuclear spectroscopy by definition a distorted signal from a saturated pre-amplifier cannot contain the correct energy information, being this one directly related to the signal amplitude. In this work we propose an innovative technique to exploit the charge-conservation principle to extract highresolution energy information from a deeply saturated chargesensitive pre-amplifier connected to semiconductor detectors. The previously described "Fast-Reset" technique enables to reconstruct the energy information from a saturated preamplifier collecting the charge on the input node with a current generator and performing a time-over-threshold measurement. However it requires an off-line post processing of the acquired data. The proposed circuit, instead, requires no post processing thanks to a peculiar Time-to-Amplitude converter that integrates a baseline rejection circuit. In this way an extension of the pre-amplifier spectroscopic energy range of a factor 20 or more is possible, with the generation of a signal whose shape is optimized for direct acquisition with a pulse-height analyzer and no additional filtering.

Equivalent Noise Charge Contribution of the √f Parallel Noise in Nuclear Spectroscopic Measurements Using Different Shaping Amplifiers

“…To verify the theoretical results obtained in the previous paragraphs, a 100 MΩ, 6 pF poly-silicon RWDC was used as feedback resistor of an integrated CSP (Charge Sensitive Pre-Amplifier) [12] with the fast-reset feature de-activated [15], [16], [17]. This pre-amplifier has been previously characterized [18] and shows a sufficiently low noise to allow for the measurement.…”

N3G project: front-end electronics and mechanical advances

“…The time required for the complete charge collection is proportional to the charge released during the saturation interaction plus the residual charge due to the pre-event baseline level [17,18]. Other solutions have been developed to remove the contribution from the baseline itself [19]. The CSP behavior during the reset phase is pictured in figure 3.…”