Direct observation of the effects of fission events has been made in thin films of Al and Pt by transmission electron microscopy.

A very thin layer (10 to 20 A thick) of UO2 was incorporated between evaporated metal films. The samples were exposed to a total thermal neutron flux of 2.8×1015 n/cm2. The fission fragments produced tracks in the matrix, the characteristic appearance of which is strongly influenced by the thickness and the atomic number of the matrix.

The mechanism of track formation is discussed from the viewpoint of dissipation of energy by the thermal spike mechanism.

1.
E.
Silk
and
R.
Barnes
,
Phil. Mag. (8)
4
,
970
(
1959
).
2.
J.
Kelsch
,
O.
Kammerer
, and
P.
Buhl
,
Brit. J. Appl. Phys.
11
,
555
(
1960
).
3.
T. S.
Noggle
and
J. O.
Stiegler
,
J. Appl. Phys.
31
,
2199
(
1960
).
4.
T. K.
Bierlein
and
B.
Mastel
,
J. Appl. Phys.
31
,
2314
(
1960
).
5.
During evaporation and subsequent exposure to air, the uranium layer undoubtedly is converted in large part to UO2.
6.
J. Brinkman, Seminar in Fission Damage in Metals, given during summer course in “Radiation Damage in Solids,” at Centro di Studi Nucleari di Ispra, September, 1960 (unpublished).
7.
H.
Brooks
,
Am. Rev. Nuclear Sci.
6
,
215
(
1956
);
J. J. Dienes and G. H. Vineyard, Radiation Effects in Solids (Interscience Publishers, Inc., New York, 1957), pp. 32–41;
F. Seitz and J. S. Koehler in Solid State Physics, edited by F. Seitz and D. Turnbull (Academic Press Inc., New York, 1956), Vol. 2, pp. 307–442.
8.
C. B. Fulmer, “Fission fragment studies by magnetic analysis,” Oak Ridge National Laboratory Report, ORNL‐2320 (unpublished).
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