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eached thermal equilibrium in an in-pile experi-
ment. Whether or not the effect does result from
neutron irradiation has not yet been determined.
A series of exposures were also made in a
5 x 104-r/hr Co60 source, and the voltage-current
characteristics of the rectifier were measured
after the samples were removed from the source.
The change in the characteristic curve can be
seep in Fig. 4.2.15. There is little change in the
forwani curve, which is in agreement with the data
in Fig. 4.2.14. The current at 1-v reverse bias
was normalized to make the preirradiation value
coincide with that of the sample exposed in the
2 x 1O6-r/hr Cod’ source. The normalized data
are shown in Fig. 4.2.14.
UNCLASSIFED
and slope. The magnitude of the current at 1-v
bias changed by a factor of about 6, and the slope
PERfOD ENDING JUNE IO, 1956
changed by a factor of about 5.3. The changes in
the chorocteristics are similar to those caused by
neutron irradiation.”
A series of transistors were irradiated in the
circuit shown in Fig. 4.2.16 to measure the ampli-
fication of the unit during, as well as before and
after, irradiation. The series resistances in the
emitter and in the collector circuit were changed
to match the unit being considered in each experi-
ment. Provisions were mode to switch from
grounded-emitter to grounded-base circuitry so that
both types of circuitry could be studied simul-
taneously with the same unit. Exposures were
made both in Coda gamma-ray sources and in the
ORNL Graphite Reactor.
The changes in the collector current at a 2-v
bias and in the amplification of a Minneapolis-
Honeywell H-2 power transistor as a function of
gamma irradiation may be seen in Fig. 4.2.17. The
collector, base, and emitter voltages were adjusted
to the originai values before each reading. Hence,
the changes in amplification were due to changes
in characteristics and not to changes in operating
voltages. It may be seen that the collector current
and the amplification were essentially the inverse
of each other. Whether the change in amplification
was due to a change in the slope of the collector
characteristic, a change in separation of the
collector curves, or a change in impedance match-
ing has not yet been determined.
The changes in amplification of two Minneapolis-
Honeywell power transistors as a function of
irradiation in hale 51-N of the ORNL Graphite
Reactor are shown in Fig. 4.2.18. These curves
illustrate the same type of behavior as that ob-
served for RCA transistor No. 1241.32 The tempo-
rary increase in amplification observed previously
in RCA transistor No. 1266 was not noted. Again,
s such that this region of the
been traversed before thermal
in-pi le experiment.
ield on Diffusion
31J. C. Pigg, Solid State Semiann. Prog. Rep. Aug.
31, 1953. ORNL-1606, p 81.
32J. C. Pigg and J. W. Clslond Solid State Semiann.
Prog. Rep. Feb. 10, 1953, ORNL-1506, p 47.
245