Ernest Graves
A:
With instruments. One of the ways that you measured radioactivity in those days was
to put out samples of material which would be activated by neutrons. Then you
measured the activation of the material and based on that level, compared to a standard
sample, you could then calculate the integrated dose on that sample. We put out these
chains of these samples on wire rope. When the test was over, the samples were pulled
to a safe distance with a truck. Since the test was on a tower, the area close to the test
was too radioactive to enter immediately. The samples had to be recovered fairly
quickly before the "induced radioactivity" in them decayed too much. We were involved
in days of counting these samples to gather the data and analyze how intense the
radiation had been at various distances from the weapon.
Q:
Did you witness it--aboard the ship, I suppose.
A:
Yes. Some of the ships moved up near the test island when we were getting ready.
Then, when everything was in readiness, all the ships moved down to the southern
portion of the atoll. You can't see the northernmost islands from the south. It is almost
25 miles from north to south so there was no problem with getting far enough away for
the size test we were doing.
But you could see the test clearly. They were like what you have seen on television or
in the movies many, many times. You don't look directly at the test because there is
high intensity light and radiation right at the time of the test. That can be damaging to
your eyes if you are looking at the weapon. You can look at it indirectly in a mirror or
through some heavy glass that shields out the radiation.
Q:
Was this the first time you had actually seen a test?
A:
Yes. We had seen movies taken of the Alamogordo shot, of course. And there were
quite a few movies taken of the Bikini shots.
Subsequent to those tests they improved the test procedures. The Alamogordo shot had
been on a relatively low tower. These tests were on higher towers. That had to do
largely with getting the devices up in the air enough so they could make better
measurements on things like the fireball to improve the measurement of the efficiency
of the weapon. One of the ways they did that was by measuring the rate at which the
fireball grows in the first fractions of a second. They had very high speed cameras that
would take pictures. The rate at which the fireball grows is a function of the energy of
the weapon. Analyzing those pictures was one of the ways they had of determining the
weapon yield.
There is a whole series of ways of measuring efficiency. In those tests, one of the
important things they were doing was to try all these different methods to see which
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