Neutron Activation Analysis (NAA)

              VOLUME I NUl.ffiER k NOVEMBER 22. 1976
NEUTRON ACTIVATION ANALYSIS (NAA) by Emory Brown, Jr.
(A special thanks to Harold Weisberg, without whose many personal sacrifices
this and other such information would not have become available.)
On November 23, 1963, the FBI laboratory conducted a series of Spectrographic
analyses on certain of the ballistical evidence associated with the assassina­tion
of President Kennedy. In addition, the bullet which had reportedly been
fired into the residence of General Walker, earlier that year underwent the same
examination. The purpose of the tests was to measure the presence of some eleven
chemical elements commonly found in bullet metal and thereby determine what, if
any, relationship there might be between the various bullets and bullet fragments.
Later that same day, a five page FBI report containing a summary of the test
results was forwarded to Dallas Police Chief Jesse E. Curry.(1) The report,
which was signed by the late J. Edgar Hoover, concluded that the bullet frag­ments
from President Kennedy, Governor Connally, the lead residue from the wind­shield
and the fragments found under Mrs. Connally's jump seat, were only "sim­ilar"
in composition which was another way of saying that they did not all come
from the same type of ammunition.
During the same series of tests, it was also revealed that the Walker bullet
did not match any of the assassination specimens, including CE:399, the Magic
Bullet.
Of particular interest to this researcher was the fact that none of the
assassination specimens (the Walker bullet as well) could be matched spectro-graphically
with the comparison samples used by the FBI laboratory personnel.(2)
The significance of this discovery will be discussed later.
Even if no one else caught the possible implications of the Spectro results.
Hoover certainly did and requested the Atomic Energy Commission to perform ad­ditional
tests at their Oak Ridge National Laboratory. During May of 196M-, cer­tain
of the ballistical evidence was subjected to a highly sensitive analytical
technique known as Neutron Activation Analysis (NAA). In NAA, a specimen is
placed in the core of an atomic reactor where, after being bombarded by neutrons,
it'will begin to emit Gamma rays. Each of the elements in nature will giveoff
these rays at a given intensity and for a known length of time. With special
detection instruments, it is possible to determine which elements are present
and in what proportion. The measurements are recorded in parts per million and
often in amounts as small as one billionth of a gram.(3)
The results of the NAA tests are contained in a seventy-five page report con­sisting
of handwritten laboratory notes. To gain a better understanding of the
technical aspects of the procedure, I contacted Dr. Vincent P. Guinn, Professor
of Chemistry at the University of California and leading expert in the field of
NAA The findings presented in two of the papers he had worked on, soon gave me
to u.-i-:erstand that the NAA results were even more damaging to the Government's
case,'than those of the Spectrographic analyses.(^)
In his work with bullet specimens, Dr. Guinn had found that the usual standard
deviation of the Antimony concentration within a single bullet or box of bullets
was about plus or minus three percent and that the Antimony concentrations