Enhanced processing circuit for spectrometry system and spectrometry system using same
This is a processing circuit for a spectrometry chain including a particle radiation detector ( 21 ), including a charge preamplifier stage ( 20 ) receiving a current (I 1 ) from the detector, representative of the amount of charges emitted by a particle which has interacted with the detector, and an integrator stage ( 26 ). A differentiator stage ( 25 ) is connected between the charge preamplifier stage ( 20 ) and the integrator stage ( 26 ), the differentiator stage ( 25 ) receiving a signal (V 1 ) from the charge preamplifier stage ( 20 ) and delivering to the integrator stage ( 26 ), a signal (V 2 ), image of the detector current (I 1 ), the integrator stage ( 26 ) delivering, an image (V 3 ) of the amount of charges emitted by a particle which has interacted with the detector. Application notably to the high energy single channel probes.
1. A processing circuit for a spectrometry chain including a particle radiation detector ( 21 ), including a charge preamplifier stage ( 20 ) receiving a pulsed current (I 1 ) from the detector, representative of the amount of charges emitted by a particle which has interacted with the detector, an integrator stage ( 26 ), a differentiator stage ( 25 ) connected to the charge preamplifier stage ( 20 ), the differentiator stage ( 25 ) receiving a signal (V 1 ) from the charge preamplifier stage ( 20 ) and delivering to the integrator stage ( 26 ), a signal (V 2 ), image of the detector current (I 1 ), the integrator stage ( 26 ) delivering an image (V 3 ) of the amount of charges emitted by a particle which has interacted with the detector, characterized in that the integrator stage ( 26 ) is formed with an integrator which cooperates with means ( 28 , 29 ), SW′ 1 , SW′ 2 ) for controlling the integration time substantially during the duration of each pulse of the detector current, the differentiator stage ( 25 ) being directly connected to the assembly formed with the integrator and means for controlling the integration time, the differentiator stage ( 25 ) and the assembly forming a band-pass filter with self-adaptive time constants.
2. The processing circuit according to claim 1 , characterized in that the charge preamplifier stage ( 20 ) includes a discrete or integrated amplifier (A′ 1 ) mounted as a current integrator.
3. The processing circuit according to claim 1 , characterized in that the differentiator stage ( 25 ) includes an operational amplifier (A′) mounted as a differentiator.
4. The processing circuit according to claim 1 , characterized in that the integrator stage ( 26 ) includes an operational amplifier (A′ 2 ) mounted as an integrator.
5. The processing circuit according to claim 1 , characterized in that the means for controlling the integration time include a first switch (SW′ 1 ) inserted between the integrator and the output of the differentiator stage ( 25 ), a second switch (SW′ 2 ) for resetting the integrator to zero, a logic circuit ( 28 ) for controlling the switches, a comparator ( 29 ) for enabling the logic circuit ( 28 ) according to the result of a comparison between the signal, image of the detector current (B 2 ), and a threshold (s′).
6. A spectrometry chain including a particle radiation detector ( 21 ), characterized in that it includes downstream from the detector ( 21 ), a processing circuit according to claim 5 .
7. A spectrometry chain including a particle radiation detector ( 21 ), characterized in that it includes downstream from the detector ( 21 ), a processing circuit according to claim 1 .
8. The spectrometry chain according to claim 7 , characterized in that it includes a circuit for acquiring ( 27 ) the signal (V 3 ) delivered by the integrator stage ( 26 ) of the processing circuit, this acquisition circuit ( 27 ) including a analog/digital converter ( 27 . 2 ) followed by a memory ( 27 . 1 ).
9. The spectrometry chain according to claim 8 , characterized in that a signal (ACT) delivered by the logic circuit ( 28 ) conditions the acquisition time.
10. The spectrometry chain according to claim 7 , characterized in that the detector ( 21 ) is inserted with a resistor (R′p) into a divider bridge circuit.
11. The spectrometry chain according to claim 7 , characterized in that the detector ( 21 ) is a semiconductor detector.
12. The spectrometry chain according to claim 11 , characterized in that the semiconducting material is selected from the group comprising CdZnTe, CdTe:Cl, CdTe:In.