Method and apparatus for compensating for neutron induced frequency shifts in quartz resonators
AssigneeThe United States of America as represented by the Secretary of the Army
InventorJohn R. Vig
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Abstract
A neutron radiation insensitive crystal oscillator. The device includes two crystals with neutron sensitivity coefficients of opposite sign. The crystals may be connected either in parallel or series relationships. The addition of tuning reactances to the circuit permits control of the circuit's overall resonance.
Claims26
A method of reducing the effects of neutron radiation acting on a crystal resonator which is the primary frequency determining element of a crystal controlled oscillator, comprising the steps of:
- determining the value of the neutron sensitivity coefficient for a first crystal;
- determining the value of the neutron sensitivity coefficient for a second crystal, said first crystal having a positive neutron sensitivity coefficient and said second crystal having a negative neutron sensitivity coefficient;
- electrically coupling said two crystals as a composite crystal resonator to an electrical oscillator circuit;
- and
- coupling electrical reactance means to one of said crystals for cancelling any difference in the resulting neutron sensitivity of said composite crystal.
The apparatus for reducing the effects of vibration on a piezoelectric crystal resonator constituting the primary frequency determining element of a crystal controlled oscillator, comprising:
- an oscillator;
- a composite crystal resonator coupled to said oscillator and comprising first and second resonator crystals, each having a neutron sensitivity coefficient of unequal magnitude, said crystals being further positioned such that the neutron sensitivity coefficient of the first crystal is of opposite sign to the neutron sensitivity coefficient and said second crystal whereby the effective neutron sensitivity of the resonant frequency of the composite crystal resonator is substantially reduced;
- and
- electrical reactance meand coupled to at least one of said first and second resonator crystals for cancelling any net neytron sensitivity between said crystals.
Dependencies are inferred from the claim text.