G-270
-2In the October 9 experiment, code-named PAR,
a
specially designed nuclear explosive system containing
a uranium, U-238, target was detonated at a depth of
1330 feet in the alluvium of the AEC's Nevada Test
Site. The explosion had a yield of about 30 kilotons.
The explosive was designed to enable the U-238 nuclei
present in the target to absorb the maximum number of
neutrons.
Following capture of the neutrons,
the uranium
isotopes underwent beta-decay to form heavier elements
in the periodic table.
This process was first observed in the initial
hydrogen bomb test, MIKE, in the Pacific in 1952.
In
the debris of MIKE, scientists discovered element 99,
einsteinium, and 100, fermium, created by multiple neutron capture by the uranium present.
Partly as a result
of MIKE, cosmologists now believe that this process
occurs in stars and plays an important role in the synthesis of elements in nature.
Analysis of small samples of fused glass,
obtained
by drilling to the region involved in the explosion of
PAR, shows that the explosion yielded a neutron flux
approximately three times greater than that of the 1952
MIKE test.
The PAR flux was twice as great as has been
achieved in previous Plowshare underground experiments.
A major indication of success is the concentration 1,000 times greater than previously achieved - of californium-254,
element 98,
in the PAR samples.
Observations on
the yields of CF-254 and other heavy species are in general
agreement in the four laboratories studying PAR samples Lawrence Radiation Laboratories at Livermore and Berkeley,
California; Los Alamos Scientific Laboratory,
Los Alamos,
New Mexico; and Argonne National Laboratory, Lemont, I1llinois.
So far, the scientists have observed elements as
heavy as fermium-255, which requires successive captures
of 17 neutrons.
The scientists are looking in the samples
even further up the periodic table for other isotopes,
including fermium-257.
The discovery of this significant
isotope was reported only last month by Livermore scientists
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