Drift-type detector with limited noise level

1. A detector appliance for detecting quanta of electromagnetic radiation. comprising:

a semiconductor detector component adapted to be exposed to electromagnetic radiation,

a amplifier component integrated with said semiconductor detector component to form a drift detector,

a neutralising current path for conducting a neutralising current through said amplifier component to said semiconductor detector component, and

a timing channel adapted to produce an indication of a detection event,

a switch coupled to said neutralising current path, said switch being adapted to control the flowing of said neutralising current and being responsive to an indication obtained from said timing channel by increasing neutralising current for a time interval following an indication obtained from said timing channel, and

a delay element between said timing channel and said switch for delaying the beginning of said time interval by a predetermined amount of time after obtaining an indication from said timing channel.

2. A detector appliance according to claim 1 , wherein said neutralising current path is responsive to a magnitude of said indication obtained from said timing channel by determining an amount of neutralisation current to flow.

3. A detector appliance according to claim 1 , wherein said timing channel is adapted to inhibit measurement in the detector appliance during said time intervel.

4. A detector appliance according to claim 1 , comprising:

a controllable amplifier on said neutralising current path and

a monitoring and feedback element coupled between said amplifier component and said controllable amplifier and adapted to control said controllable amplifier on the basis of monitored change of potential in said amplifier component, said change of potential being indicative of an amount of accumulated charge in said semiconductor detector component.

5. A detector appliance according to claim 1 , comprising a timer coupled to control said switch and adapted to repeatedly set said switch Into conductive and non-conductive state.

6. A detector appliance according to claim 5 , comprising:

a monitoring and feedback element coupled to said amplifier component and adapted to monitor a change of potential in said amplifier component, said change of potential being indicative of an amount of accumulated charge in said semiconductor detector component, and

a feedback coupling from said monitoring and feedback element to said timer.

7. A detector appliance according to claim 5 , comprising:

a timing channel adapted to produce indications of detection events and

a feedback coupling from said timing channel to said timer.

8. A detector appliance according to claim 5 , wherein said timer is adapted to produce an inhibit signal for inhibiting measurements in said detector appliance during times when said switch is in a state allowing increased flow of neutralising current.

9. A detector appliance for detecting quanta of electromagnetic radiation, comprising:

a drift detector chip comprising a detector diode and an integrated field-effect transistor adapted to act as an amplifying component,

a preamplifier with an input coupled to a source electrode of said integrated field-effect transistor and an output,

a linear amplifier having an input coupled to the output of said preamplifier and comprising a timing channel adapted to produce a timing pulse,

a latch circuit coupled to receive a timing pulse from said timing channel and adapted to sample a received timing pulse and to temporarily store a sampled received timing pulse,

a neutralisation current switch coupled between said latch circuit and said integrated field-effect transistor,

a latch emptying switch coupled between said latch circuit and a fixed potential, and

a pulse generator having an input coupled to receive a timing pulse from said timing channel, a first output coupled to control a state of conduction of said neutralisation current switch and a second output coupled to control a state of conduction of said latch emptying switch;

wherein said pulse generator is adapted to respond to receiving a timing pulse by first setting said neutralisation current switch into conductive state and thereafter setting said neutralisation current switch into non-conductive state and said latch emptying switch into conductive state.

10. A detector appliance according to claim 9 , additionally comprising a controllable amplifier on a current path between said latch circuit and said integrated field-effect translator, and additionally comprising a monitoring and feedback element coupled between said Integrated field-effect transistor and said controllable amplifier and adapted to control said controllable amplifier on the basis of monitored change of potential in said integrated field-effect transistor, said change of potential being indicative of an amount of accumulated charge in said detector diode.

11. A detector appliance for detecting quanta of electromagnetic radiation, comprising:

a drift detector chip comprising a detector diode and an integrated field-effect transistor adapted to act as an amplifying component,

a preamplifier with an input coupled to a source electrode of said integrated field-effect transistor and an output,

a linear amplifier having an input coupled to the output of said preamplifier and being adapted to produce an amplified pulse indicative of a hit of a quantum being detected in the detector diode.

a neutralisation current switch coupled between a neutralisation current source and said integrated field-effect transistor, and

a timer having an output coupled to control a state of conduction of said neutralisation current switch;

wherein said timer is adapted to repeatedly set said neutralisatlon current switch into conductive state and thereafter into non-conductive state.

12. A detector appliance according to claim 11 , additionally comprising a controllable amplifier on a current path between said neutralisation current source and said integrated field-effect transistor, and additionally comprising a monitoring and feedback element coupled between said integrated field-effect transistor and said controllable amplifier and adapted to control said controllable amplifier on the basis of monitored change of potential in said integrated field-effect transistor, said change of potential being indicative of an amount of accumulated charge in said detector diode.

13. A detector appliance according to claim 12 , wherein said monitoring and feedback element is additionally adapted to control an operational characteristic of said timer on the basis of monitored change of potential in said integrated field-effect transistor, said change of potential being indicative of an amount of accumulated charge in said detector diode, and said operational characteristic comprising at least one of: operating frequency, duty cycle.

14. A method for neutralising accumulated charge in a drift detector, comprising:

producing an indication of an occurred hit of a quantum in the drift detector, and

based on said indication, triggering a pulse of deliberately increased neutralisation current into the drift detector for the duration of a limited time interval.

15. A method according to claim 14 , wherein a pulse of deliberately increased neutralisation current is triggered as a response to each individually produced indication of an occurred hit of a quantum in the drift detector.

16. A method according to claim 15 , wherein said indication is a timing pulse obtained from a timing channel of a linear amplifier, and the method comprises:

sampling said timing pulse and storing the sampled timing pulse in a form of voltage,

waiting for a predetermined delay and

after said predetermined delay, releasing the sampled timing pulse from storage to a neutralisation current path leading to the drift detector.

17. A method according to claim 14 , additionally comprising:

monitoring the accumulation of charge in the drift detector and

tuning an amount of how much said neutralisation current is increased, in proportion to monitored accumulation of charge in the drift detector.

18. A method according to claim 14 , wherein a pulse of deliberately increased neutralisation current is triggered as a response to an accumulated number of individually produced indications of occurred hits of a quantum in tile drift detector.

19. A method for neutralising accumulated charge in a drift detector, comprising:

regularly triggering a pulse of deliberately increased neutralisation current into the drift detector for the duration of a limited time interval, and

tuning an operational characteristic of such regular triggering in proportion to monitored accumulation of charge in the drift detector, the operational characteristic being at least one of the following: an amount of how much said neutralisation current is increased, a frequency at which triggering occurs, a duty cycle of triggered pulses of deliberately increased neutralisation current.