Radiation measurement system with automatic standardization using a rate feedback signal

Claim 5

The method of claim 2 wherein a standardizing complete signal is generated when the output signal is below a predetermined level.

Claim 6

The method of claim 2 wherein a standardizing complete signal is generated when the output signal is below a predetermined level for more than a predetermined time.

Claim 13

The method of claim 7 wherein said system is zero standardized periodically.

Claim 14

The method of claim 7 wherein the gain of summing amplifier means is made greater during zero and source standardizing than during measuring.

Claim 15

A standardization circuit for a radiation gauge including an electrometer for providing a d.c. electrometer signal, comprising summing amplifier means having first, second and third input terminals and an output terminal, said summing amplifier means developing on the output terminal an output signal which is a function of the sum of signals proportional to respective signals applied to the respective first, second and third input terminals, adjustable means for adjustably varying the electrometer signal derived from said electrometer, which electrometer signal is coupled to said first input terminal, a d.c. reference signal coupled to said second input terminal, first feedback means coupled to said output terminal and responsive to said output signal for adjusting said adjustable means in the direction to establish a predetermined relation between said electrometer signal and said reference signal at which said output signal approaches zero, and further feedback means for providing a rate feedback signal to said third input terminal corresponding to the rate of said adjustment, whereby deviations from said predetermined relation are amplified and rapidly diminished to produce said predetermined relation while simultaneously damping the adjustment of said adjustable means.

Claim 16

A standardization circuit for a radiation gauge including an electrometer for providing a d.c. electrometer signal, comprising summing amplifier means having first, second and third input terminals and an output terminal, said summing amplifier means developing on the output terminal an output signal which is a function of the sum of signals proportional to respective signals applied to the respective first, second and third input terminals, adjustable means for adjustably varying the electrometer signal derived from said electrometer, which electrometer signal is coupled to said first input terminal, a d.c. reference signal coupled to said second input terminal, first feedback means coupled to said output terminal and responsive to said output signal for adjusting said adjustable means in the direction to establish a predetermined relation between said electrometer signal and said reference signal at which said output signal approaches zero, and further feedback means for providing a rate feedback signal to said third input terminal corresponding to the rate of said adjustment, whereby deviations from said predetermined relation are amplified and rapidly diminished to produce said predetermined relation while simultaneously damping the adjustment of said adjustable means.

Claim 17

The circuit of claim 10 wherein said adjustable means comprises a potentiometer, said first feedback means comprises a servo-motor connected to the output of said amplifier means and mechanically coupled to said potentiometer, said motor driving the potentiometer in the direction to establish a zero voltage output from said summing amplifier means, and said further feedback means comprises circuit means for sensing the back EMF of said motor and applying a voltage generally proportional thereto to said third input terminal.

Claim 18

The circuit of claim 11 wherein said Circuit means comprises a resistance in series circuit relation with said motor to develop the motor back EMF across said motor, and a differential amplifier having two input terminals and an output terminal, said two differential amplifier input terminals being coupled across the motor and said output terminal being coupled to said third input terminal of said summing amplifier means, said differential amplifier developing on the differential amplifier output terminal a rate feedback signal generally proportional to the difference in the signals as applied to the respective differential amplifier input terminals.

Claim 19

The circuit of claim 10 comprising detector means coupled to the output terminal of said summing amplifier means and responsive to the output signal thereat for providing a standardizing complete signal when the output signal is below a predetermined level.

Claim 20

The circuit of claim 10 comprising detector means coupled to the output terminal of said summing amplifier means and responsive to the output signal thereat for providing a standardizing complete signal when the output signal is below a predetermined level for more than a predetermined time.

Claim 21

A standardization circuit for a radiation gauge including an electrometer for providing a d.c. electrometer signal, comprising summing amplifier means having first, second and third input terminals and an output terminal, said summing amplifier means developing on the output terminal an output signal which is a function of the sum of signals proportional to respective signals applied to the respective first, second and third input terminals, a potentiometer for adjustably varying the electrometer signal derived from said electrometer, which electrometer signal is coupled to said first input terminal, a d.c. reference signal coupled to said second input terminal, first feedback means coupled to said output terminal and responsive to said output signal for adjusting said potentiometer in the direction to establish a predetermined relation between said electrometer signal and said reference signal at which said output signal approaches zero, and further feedback means for providing a rate feedback signal to said third input terminal corresponding to the rate of said adjustment, whereby deviations from said predetermined relation are amplified and rapidly diminished to produce said predetermined relation while simultaneously damping the adjustment of said potentiometer.

Claim 22

A standardization circuit for a radiation gauge including an electrometer for providing a d.c. electrometer signal, comprising summing amplifier means having first, second and third input terminals and an output terminal, said summing amplifier means developing on the output terminal an output signal which is a function of the sum of signals proportional to respective signals applied to the respective first, second and third input terminals, a potentiometer for adjustably varying the electrometer signal derived from said electrometer, which electrometer signal is coupled to said first input terminal, a d.c. reference signal coupled to said second input terminal, first feedback means coupled to said output terminal and responsive to said output signal for adjusting said potentiometer in the direction to establish a predetermined relation between said electrometer signal and said reference signal at which said output signal approaches zero, and further feedback means for providing a rate feedback signal to said third input terminal corresponding to the rate of said adjustment, whereby deviations from said predetermined relation are amplified and rapidly diminished to produce said predetermined relation while simultaneously damping the adjustment of said potentiometer.

Claim 23

In a radiation gauge including a source of nuclear radiation for irradiating material a property of which is to be measured, an ionization chamber for detecting said radiation as influenced by said material by producing a detection signal systematically related to the radiation incident upon said chamber, and an electrometer having first and second electrometer input circuits and an electrometer output circuit, selectively operable means for applying said detection signal to said first input circuit, an adjustable source of zeroing signal coupled to said second input circuit, said electrometer providing a d.c. electrometer signal at said electrometer output circuit which is a function of the sum of signals proportional to respective signals applied to the respective first and second electrometer input circuits, a zero standardizing circuit comprising summing amplifier means having first, second and third input terminals and an output terminal, said summing amplifier means developing on the output terminal an output signal which is a function of the sum of signals proportional to respective signals applied to the respective first, second and third input terminals, a potentiometer for adjustably varying said source of zeroing signal, thereby varying said electrometer signal being coupled to said first input terminal, d.c. reference signal coupled to said second input terminal, first feedback means coupled to said output terminal and responsive to said output signal for adjusting said potentiometer in the direction to establish a predetermined relation between said electrometer signal and said reference signal at which said output signal approaches zero, and further feedback means for providing a rate feedback signal to said third input terminal corresponding to the rate of said adjustment.

Claim 24

In a radiation gauge including a source of nuclear radiation for irradiating material a property of which is to be measured, an ionization chamber for detecting said radiation as influenced by said material by producing a detection signal systematically related to the radiation incident upon said chamber, and an electrometer having first and second electrometer input circuits and an electrometer output circuit, selectively operable means for applying said detection signal to said first input circuit, an adjustable source of zeroing signal coupled to said second input circuit, said electrometer providing a d.c. electrometer signal at said electrometer output circuit which is a function of the sum of signals proportional to respective signals applied to the respective first and second electrometer input circuits, a zero standardizing circuit comprising summing amplifier means having first, second and third input terminals and an output terminal, said summing amplifier means developing on the output terminal an output signal which is a function of the sum of signals proportional to respective signals applied to the respective first, second and third input terminals, a potentiometer for adjustably varying said source of zeroing signal, thereby varying said electrometer signal being coupled to said first input terminal, d.c. reference signal coupled to said second input terminal, first feedback means coupled to said output terminal and responsive to said output signal for adjusting said potentiometer in the direction to establish a predetermined relation between said electrometer signal and said reference signal at which said output signal approaches zero, and further feedback means for providing a rate feedback signal to said third input terminal corresponding to the rate of said adjustment.

Claim 25

In radiation gauge including a source of nuclear radiation for irradiating material a property of which is to be measured, an ionization chamber for detecting said radiation as influenced by said material by producing a detection signal systematically related to the radiation incident upon said chamber, and an electrometer having an input circuit coupled to said detector and an output circuit providing a d.c. electrometer signal systematically related to said detection signal, a source standardization circuit comprising summing amplifier means having first, second and third input terminals and an output terminal, said summing amplifier means developing on the output terminal an output signal which is a function of the sum of signals proportional to respective signals applied to the respective first, second and third input terminals, a potentiometer connected in the electrometer output circuit for adjustably varying said electrometer signal in the absence of said material, which electrometer signal is coupled to said first input terminal, a d.c. reference signal coupled to said second input material, first feedback means coupled to said output terminal in the absence of said material in said gauge and responsive to said output signal for adjusting said potentiometer in the direction to establish a predetermined relation between said electrometer signal and said reference signal at which said output signal approaches zero, and further feedback means for providing a rate feedback signal to said third input terminal corresponding to the rate of said adjustment, whereby deviations from said predetermined relation are amplified and rapidly diminished to produce said predetermined relation while simultaneously damping the adjustment of said potentiometer.

Claim 26

In radiation gauge including a source of nuclear radiation for irradiating material a property of which is to be measured, an ionization chamber for detecting said radiation as influenced by said material by producing a detection signal systematically related to the radiation incident upon said chamber, and an electrometer having an input circuit coupled to said detector and an output circuit providing a d.c. electrometer signal systematically related to said detection signal, a source standardization circuit comprising summing amplifier means having first, second and third input terminals and an output terminal, said summing amplifier means developing on the output terminal an output signal which is a function of the sum of signals proportional to respective signals applied to the respective first, second and third input terminals, a potentiometer connected in the electrometer output circuit for adjustably varying said electrometer signal in the absence of said material, which electrometer signal is coupled to said first input terminal, a d.c. reference signal coupled to said second input material, first feedback means coupled to said output terminal in the absence of said material in said gauge and responsive to said output signal for adjusting said potentiometer in the direction to establish a predetermined relation between said electrometer signal and said reference signal at which said output signal approaches zero, and further feedback means for providing a rate feedback signal to said third input terminal corresponding to the rate of said adjustment, whereby deviations from said predetermined relation are amplified and rapidly diminished to produce said predetermined relation while simultaneously damping the adjustment of said potentiometer.

Claim 27

A standardization circuit for a radiation gauge including an electrometer for providing a d.c. electrometer signal, comprising summing amplifier means having first, second and third input terminals and an output terminal, said summing amplifier means developing on the output terminal an output signal which is a function of the sum of signals proportional to respective signals applied to the respective first, second and third input terminals, adjustable means for adjustably varying the electrometer signal derived from said electrometer, which electrometer signal is coupled to said first input terminal, a d.c. reference signal coupled to said second input terminal, feedback means coupled to said output terminal and responsive to said output signal for adjusting said adjustable means in the direction to establish a predetermined relation between said electrometer signal and said reference signal at which said output signal approaches zero, and detector means coupled to the output terminal of said summing amplifier means and responsive to the output signal thereat for providing a standardizing complete signal when the output signal is below a predetermined level for more than a predetermined time.

Claim 28

A standardization circuit for a radiation gauge including an electrometer for providing a d.c. electrometer signal, comprising summing amplifier means having first, second and third input terminals and an output terminal, said summing amplifier means developing on the output terminal an output signal which is a function of the sum of signals proportional to respective signals applied to the respective first, second and third input terminals, adjustable means for adjustably varying the electrometer signal derived from said electrometer, which electrometer signal is coupled to said first input terminal, a d.c. reference signal coupled to said second input terminal, feedback means coupled to said output terminal and responsive to said output signal for adjusting said adjustable means in the direction to establish a predetermined relation between said electrometer signal and said reference signal at which said output signal approaches zero, and detector means coupled to the output terminal of said summing amplifier means and responsive to the output signal thereat for providing a standardizing complete signal when the output signal is below a predetermined level for more than a predetermined time.

Claim 29

The circuit of claim 18 wherein said detector means comprises a comparator for comparing the magnitude of said output signal with a threshold reference signal having said predetermined level and providing a comparator signal when said output signal is below said predetermined level, a monostable multivibrator responsive to said given comparator signal for generating an enabling signal only if said comparator signal extends for said predetermined period of time, logic means coupled to said comparator and to said multivibrator for providing a standardization complete signal only on coincidence of said comparator signal and said enabling signal.

Claim 30

A radiation measurement system comprising a source of nuclear radiation for irradiating a material a property of which is to be measured, an ionization chamber for detecting said radiation as influenced by said material by producing a detection signal systematically related to the radiation incident upon said chamber, an electrometer having first and second input circuits and an output circuit, an adjustable source of zeroing signal coupled to said second input circuit of said electrometer, said electrometer providing a d.c. electrometer signal at said electrometer output circuit which is a function of the sum of signals proportional to respective signals applied to the respective first and second electrometer input circuits, gain control means for controlling the relative magnitude of said d.c. electrometer signal, summing amplifier means having first, second and third input terminals and an output terminal, said summing amplifier means developing on its output terminal an output signal which is a function of the sum of signals proportional to respective signals applied to its respective first, second and third input terminals, means applying said d.c. electrometer signal to said first input terminal, and means for operating said system successively in a zero standardizing mode, a source standardizing mode and a measurement mode, A. said means for operating said system in the zero standardizing mode comprising first adjustable means for adjustably varying said source of zeroing signal coupled to said second electrometer input circuit, means for applying a zero input signal to said first electrometer input circuit, means for applying a zero reference signal to said second input terminal of said summing amplifier, first feedback means coupled to said output terminal and responsive to said output signal for adjusting said adjustable means in the direction reducing said output signal, and first rate feedback means for providing a first rate feedback signal to said third input terminal corresponding to the rate of said adjustment of said first adjustable means, B. said means for operating said system in the source standardizing mode comprising means for moving said radiation source and detector relative to the material to subject a standard material to said radiation, means for applying said detection signal to said first electrometer input circuit, a source standardize d.c. reference signal, means for coupling said source standardize reference signal to said second input terminal, second feedback means coupled to said output terminal and responsive to said output signal for adjusting said gain control means in the direction to establish a predetermined relation between said electrometer signal and said source standardize reference signal at which said output signal approaches zero, and second rate feedback means for providing a second rate feedback signal to said third input terminal corresponding to the rate of adjustment of said gain control means, and C. said means for operating said system in the measuring mode comprising means for moving said radiation source and detector relative to the material to subject the material to said radiation, said detection signal being applied to said first electrometer input circuit, a predetermined zero suppression d.c. reference signal, means for coupling said zero suppression reference signal to said second input terminal, and means coupled to said output terminal and responsive to said output signal to provide a signal indicative of the material property being measured.

Claim 31

A radiation measurement system comprising a source of nuclear radiation for irradiating a material a property of which is to be measured, an ionization chamber for detecting said radiation as influenced by said material by producing a detection signal systematically related to the radiation incident upon said chamber, an electrometer having first and second input circuits and an output circuit, an adjustable source of zeroing signal coupled to said second input circuit of said electrometer, said electrometer providing a d.c. electrometer signal at said electrometer output circuit which is a function of the sum of signals proportional to respective signals applied to the respective first and second electrometer input circuits, gain control means for controlling the relative magnitude of said d.c. electrometer signal, summing amplifier means having first, second and third input terminals and an output terminal, said summing amplifier means developing on its output terminal an output signal which is a function of the sum of signals proportional to respective signals applied to its respective first, second and third input terminals, means applying said d.c. electrometer signal to said first input terminal, and means for operating said system successively in a zero standardizing mode, a source standardizing mode and a measurement mode, A. said means for operating said system in the zero standardizing mode comprising first adjustable means for adjustably varying said source of zeroing signal coupled to said second electrometer input circuit, means for applying a zero input signal to said first electrometer input circuit, means for applying a zero reference signal to said second input terminal of said summing amplifier, first feedback means coupled to said output terminal and responsive to said output signal for adjusting said adjustable means in the direction reducing said output signal, and first rate feedback means for providing a first rate feedback signal to said third input terminal corresponding to the rate of said adjustment of said first adjustable means, B. said means for operating said system in the source standardizing mode comprising means for moving said radiation source and detector relative to the material to subject a standard material to said radiation, means for applying said detection signal to said first electrometer input circuit, a source standardize d.c. reference signal, means for coupling said source standardize reference signal to said second input terminal, second feedback means coupled to said output terminal and responsive to said output signal for adjusting said gain control means in the direction to establish a predetermined relation between said electrometer signal and said source standardize reference signal at which said output signal approaches zero, and second rate feedback means for providing a second rate feedback signal to said third input terminal corresponding to the rate of adjustment of said gain control means, and C. said means for operating said system in the measuring mode comprising means for moving said radiation source and detector relative to the material to subject the material to said radiation, said detection signal being applied to said first electrometer input circuit, a predetermined zero suppression d.c. reference signal, means for coupling said zero suppression reference signal to said second input terminal, and means coupled to said output terminal and responsive to said output signal to provide a signal indicative of the material property being measured.

Claim 32

The system of claim 20 comprising detector means coupled to the output terminal of said summing amplifier means and responsive to the output signal thereat for providing a standardizing complete signal when the output signal is below a predetermined level for more than a predetermined time while the system is in a standardizing mode, and means responsive to a standardizing complete signal for advancing the system to the next successive mode.

Claim 33

The system of claim 21 comprising means for periodically placing the system in the zero standardizing mode.

Claim 34

The sYstem of claim 20 further including a span control comprising further gain control means for controlling the gain of said summing amplifier means, and means for adjusting said further gain control means to provide substantially greater gain in said summing amplifier means in said zero and source standardizing modes than in said measuring mode.