Speakers
Dr
Angelo La Manna
(Università di Palermo Dipartimento di Fisica e Tecnologie Relative)Prof.
Gaetano Gerardi
(Università di Palemo Dipartimento di Fisica e Tecnologie Relative)
Description
Pile-up distortion is a major drawback in X-ray spectroscopy at high count rate.
Signal processing can help to overcome this problem. Pulse width narrowing with
shaping tecniques can lead to reduction of pile-up distortion; however, a low
shaping time reduces the noise filtration and leads to a poor energy resolution.
Hence the optimum shaping time is a compromise between noise and pile-up
requirements.
In this work a digital signal processing sytem for X-ray spectrometers operating at
high count rate is described. The system processes the output signal of a Charge
Sensitive Preamplifier (CSPA) connected to a X-ray semiconductor detector. The
output signal is registered by a high speed ADC (sampling rate up to 100 MHz, 14
bit resolution) and a fully digital shaping is carried out off-line by a dedicated
software instead of traditional analog electronics. The software calculates the
incident photon count and the energy spectrum as well. The system can deal with
count rate up to 150,000 counts/s.
The benefits of the fully digital off-line shaping respect to the traditional
analog shaping are emphasized. Using analog systems, shaping time tuning requires
hardware manipulation. Otherwise, digital signal processing allows the shaping time
to changes by simply acting on software settings, reducing costs and improving ease
of operation.
The system, described in this paper, carries out the complete signal processing and
analisys as well (filtering, pole-zero cancellation, peak detection, pile-up
detection and correction).
The acquisition and signal processing software has been developed using LABVIEW
platform. The software is characterized by a user friendly GUI to makes easy
parameter adjustement and software setting.
Tests with simulated and directly measured signals show a good system ability
Author
Prof.
Gaetano Gerardi
(Università di Palemo Dipartimento di Fisica e Tecnologie Relative)
Co-authors
Dr
Angelo La Manna
(Università di Palermo Dipartimento di Fisica e Tecnologie Relative)
Prof.
Francesco Fauci
(Università di Palermo Dipartimento di Fisica e Tecnologie Relative)
Prof.
Giuseppe Raso
(Università di Palermo Dipartimento di Fisica e Tecnologie Relative)
Dr
Leonardo Abbene
(Università di Palermo Dipartimento di Fisica e Tecnologie Relative)