Evening star., 1950-01-19
By Thomas R. Henry

Behind the present scare propa-
ganda about a possible hydrogen
bomb, 1000 times more powerful
than the uranium bomb" lies one
possibility that falls snort of the
completely fantastic and incred-
ible.
This, in the opinion of Wash
ington physicists free to speculate,
must represent the slight core of
fact In the scare stories. Any
Atomic Energy Commission en-
ploye and physicists in most Gov
eminent departments are pro-
hibited from discussing the matter
with outsiders.
This possibility is the hydro
-lithium" bomb which, the
oretically, might produce about
eight-fold more energy per unit
weight than plutonium or uranium
235, the explosive ingredients of
the present bomb.
In the new type bomb, how
ever, the present plutonium bomb
would be used as primer to get
reaction started. The story goes
back to 1882 and a remarkable
experiment performed by Sir
John Cockcroft, present head of
the British Atomic Energy set-up,
at the Cavandish Laboratory atI
Cambridge. This was actually
the first splitting of the atom and
aroused great deal of attention
at the time.
Cockcroft split atoms of lith-
ium. the lightest of metals and
the third lightest of all the ele-
ments, into helium by lombard
ing them with protons, or nuclei
of hydrogen atoms. A stream of
those protons was directed at an
energy Of about $4,000 electron
volts against a lithium target.
In the residue appeared alpha
particles, nuclei of helium atoms.
This is approximately what
happens. A proton, striking the
nucleus of a lithium atom, mo-
mentarily is incorporated in this
nucleus. The result is an atom of |
form of the fourth lightest ele-
ment, the metal Beryllium. This,
however, is extremely unstable. It |
exists only about a millionth of a |
second. Then it splits into two
helium nuclei.
Physicists were quite excited for
few weeks with the prospect
that the long-dreamed atomic
energy was at last achieved. It'll
was Short-lived dream. The
power that could be gotten out of
any lithium engine was only about
a millionth that expended. No
chain reaction was set up. It'll
was necessary to make direct hit
OF proton against a nucleus be-
fore anything happened. This
was purely matter of accident.
The possibilities once were de-
scribed by Einstein as like those
of a blind man killing a duck on
a dark night in a country where
there were very few ducks by
firing a rifle straight in the air.
Moreover the protons had to be
propelled with very great power
to break through the wall of re-
sistance around every atomic
nucleus.
The explosive force of the re-
action was. however, extremely |
great, considering masses involved.
A hydrogen nucleus. or proton,
weighs 1.00812 atomic units-the
units OF weight of the atomic
world.
A lithium atom weighs 7.018O4
atomic units. The weights of the
two combined during their mo-
mentary welding is S.02616 atomic
units.
The two helium nuclei into
which the extremely short-lived
beryllium splits weigh only 8.00778
atomic units.
The equivalent in mass of
.01838 mass units has changed
from matter to energy.
It turns out to be I'LL million
electron volts. This is far less
than the 100000, 900 electron volts
from the fissien of one uranium
atom. but on the other hand the
uranium nucleus weighs about sol
times as much as lithium atom.
It was obvious from the first
that the lithiumhydrogen reaction|
offered no practical POSSIBILITIES
whatsoever unless both protons
and helium- nuclei were In such
states of excitment that tfeyl
would smash constantly against
each other.
The calculations at the time
were that this would require a
temperature of at least zoo, o,000, 900
degrees heat then inconceiv-
able on earth and existing only in
the center of the sun.
But such a heat does exist in
the atomic bomb at the instant
Of its explosion. probably for as
long as a millionth of a second.
So there is possibility of sur
rounding a plutonium bomb with
shell of a mixture Of lithium and
hydrogen, a material estimated to
cost about $40 a pound. There is
o strong likelihood that the whole