Fast charge digitizer and digital data acquisition system for measuring time varying radiation fields
A radiation measuring instrument including a fast charge digitizer and a digital data acquisition system has been developed. The fast charge digitizer includes a charge integrator connected to a conventional ionization chamber which generates an output current in proportion to ionizing radiation exposure rate. The charge integrator has an output connected to a comparator which is switched from a high state to a low state when the output of the integrator goes above the comparator threshold. The comparator output is connected to a bistable multivibrator consisting of two non-retriggerable one shot multivibrators connected in a feedback configuration. As long as the comparator output is in the low state, the bistable multivibrator generates a train of pluses which are fed back through an analog switch and a high megohm resistance to the input of the integrator. This feedback is negative and has the effect of removing the charge from the integrating capacitor, thus causing the integrator output eventually to drop below the comparator threshold. When this occurs the comparator output returns to the high state and the bistable multivibrator ceases to generate output pulses. An output terminal is connected between the bistable multivibrator and the analog switch and feeds a train of pulses proportional to the amount of charge generated by the multivibrator output voltage and the high megohm resistance to a counter connected to a random access memory device. The output pulses are counted for a predetermined time and then stored in one of the data locations of the random access memory device. The counter is then reset and a further predetermined sample period is counted. This continues until all of the locations in the random access memory device are filled and then the data is read from the random access memory device.
- Assignee:
- Secretary of the Department of Health, Education and Welfare
- Patent Number(s):
- US 3959653
- Application Number:
- TRN: 76-021252
- OSTI ID:
- 7339347
- Resource Relation:
- Patent File Date: Filed date 14 Apr 1975
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
EXPOSURE RATEMETERS
DESIGN
IONIZATION CHAMBERS
COUNTING CIRCUITS
DATA ACQUISITION SYSTEMS
DIGITAL CIRCUITS
DIGITIZERS
FEEDBACK
MEMORY DEVICES
ELECTRONIC CIRCUITS
MEASURING INSTRUMENTS
RADIATION DETECTORS
RADIATION MONITORS
440101* - Radiation Instrumentation- General Detectors or Monitors & Radiometric Instruments