4-87
Fast Neutron Exposure (nvt)
x1017
0    1    2     3    4     5    6     7    8    9    10  11   12
1000
900
800
700
600
500
400
300
200
100
0
Frequency Deviation,       X106
Df
f
5 MHz
AT-cut
Slope = 0.7 x 10-21/n/cm2
Frequency Change due to Neutrons
   When a fast neutron hurtles into a crystal lattice and collides with an atom, it is scattered like a billiard ball.  A single such neutron can produce numerous vacancies, interstitials, and broken interatomic bonds (see next page).  The effect of this "displacement damage" on oscillator frequency is dependent primarily upon the neutron fluence (and not on the type of quartz).  The frequency of oscillation increases nearly linearly with neutron fluence at rates of:  8 x 10-21 neutrons per square centimeter (n/cm2) at a fluence range of 1010 to 1012 n/cm2, 5 x 10-21/n/cm2 at 1012 to 1013 n/cm2, and 0.7 x 10-21/n/cm2 at 1017 to 1018 n/cm2.


J. C. King and D. B. Fraser, "Effects of Reactor Irradiation on Thickness Shear Crystal Resonators," Proc. 16th Annual Symposium on Frequency Control, pp. 8-31, 1962, AD-285086.

T. M. Flanagan & T. F. Wrobel, “Radiation Effects in Swep-Synthetic Quartz,” IEEE Trans. Nuclear Science, vol. NS-16, pp. 130-137, Dec. 1969

W. Primak, “Extrusion of Quartz on Ion Bombardment: Further Evidence for Radiation-Induced Stress Relaxation of the Silica Network,” Phys. Rev. B, vol. 14, pp. 4679-4686, 1976.