We present a new discharge mechanism for low-noise fast preamplifiers for γ-ray spectroscopy. Such circuital solution has been conceived in the framework of the INFN Mars experiment, which imposes stringent requirements for both the signal-to-noise ratio and the rise time of the front-end preamplifiers. Basically a non-inverting low-gain (G) stage is interposed between the output of a conventional charge amplifier and the high-value feedback resistor. It can be easily found that this adds no noise but the discharge time constant is reduced by a factor G, because the voltage drop across the resistor is G times as high, and such is the discharge current. A similar effect could also be obtained in the standard charge amplifier by diminishing the feedback resistor by a factor G. But this would yield an increase of a factor G of its thermal current noise. In this sense our equivalent discharge resistor is "cold", because it carries a current noise G times as low. This permits us to use a relatively large feedback capacitance which inherently yields a fast risetime. A rise time of 15 ns and an overall electronic noise of 1.03 keV fwhm at 3 μs shaping time have been obtained, with an input capacitance of 33 pF, 1.5 pF feedback capacitor, 150 μs discharge time constant.
A "cold" discharge mechanism for low-noise fast charge amplifiers / A. Pullia, R. Bassini, C. Boiano, S. Brambilla - In: 2000 IEEE Nuclear science symposium conference record. Volume 2Piscataway, USA : IEEE, 2000. - ISBN 0-7803-6503-8. - pp. 9/196-9/200 (( convegno Nuclear science symposium and medical imaging conference tenutosi a Lyon nel 2000.
|Titolo:||A "cold" discharge mechanism for low-noise fast charge amplifiers|
PULLIA, ALBERTO (Primo)
|Parole Chiave:||charge preamplifiers ; charge sensistive preamplifiers ; cold discharge mechanism ; ionizing radiation spectroscopy ; gamma ray spectroscopy ; X ray spectroscopy|
|Settore Scientifico Disciplinare:||Settore ING-INF/01 - Elettronica|
Settore FIS/01 - Fisica Sperimentale
Settore FIS/04 - Fisica Nucleare e Subnucleare
|Data di pubblicazione:||2000|
|Enti collegati al convegno:||IEEE|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.1109/NSSMIC.2000.949899|
|Tipologia:||Book Part (author)|
|Appare nelle tipologie:||03 - Contributo in volume|