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KALKSTEIN, THOMASIAN, AND NIKULA
with the principal disturbances occurring late in the winter.® This also
is reflected in the measurements of the concentrations of !°°Cd, with
the high-latitude increase in the northern hemisphere first beginning
about December or January and reaching high levels in March and
April of 1964, In addition, the northern-hemisphere concentrations
have been consistently lower than those in the southern hemisphere.
The latest stratospheric concentrations presented here correspond
roughly to one-half of what was expected on the basis of the ‘Rh experiment. This could be due to less than average transport of the !°°Cd
tracer to the low stratosphere, escape of some of the tracer from the
earth’s magnetic and gravitational field, or a lower production of the
108°Cd than 0.25 Mc. The last possibility would be consistent with the
value of about 0.12 Mc estimated by Cowan.”
REFERENCES
1, U.S, Atomic Energy Commission Health and Safety Laboratory Cadmium-109
Conference, Dec. 6, 1963. (A ““best’’ estimate of 0.25 + 0.15 Mc of Cd!was
arbitrarily adopted.)
2. I, J. Russell and R.V, Griffith, The Production of Cd!® and Cd!!3™ in a Space
Nuclear Explosion, in Fallout Program Quarterly Summary Report, USAEC
Report HASL-142, pp. 306-322, Health and Safety Laboratory, Jan. 1, 1964.
3, M,I. Kalkstein, Rhodium-102 High Altitude Tracer Experiment, Science, 137:
645 (1962),
4, L, P, Salter, in U. S, Atomic Energy Commission Health and Safety Laboratory Cadmium-109 Conference, Dec. 6, 1963.
5, H. Wexler, Seasonal and Other Temperature Changes in the Antarctic Atmosphere, Quart. J. Roy. Meteorol. Soc., 85: 196 (1959).
6. W. S. Hering, Air Force Cambridge Research Laboratories, private communication, July 1964,
7, G, A, Cowan, memorandum to the U, S, Atomic Energy Commission Health
and Safety Laboratory Cadmium-109 Conference, Dec. 6, 1963.