hn-classics/_stories/2003/293488.md

---
created_at: '2008-09-03T03:02:16.000Z'
title: How two students built an A-bomb (2003)
url: http://www.guardian.co.uk/world/2003/jun/24/usa.science
author: ken
points: 60
story_text: ''
comment_text: 
num_comments: 15
story_id: 
story_title: 
story_url: 
parent_id: 
created_at_i: 1220410936
_tags:
- story
- author_ken
- story_293488
objectID: '293488'
year: 2003

---
It's one of the burning questions of the moment: how easy would it be
for a country with no nuclear expertise to build an A-bomb? Forty years
ago in a top-secret project, the US military set about finding out.
Oliver Burkeman talks to the men who solved the nuclear puzzle in just
30 months

Dave Dobson's past is not a secret. Not technically, anyway - not since
the relevant US government intelligence documents were declassified and
placed in the vaults of the National Security Archive, in Washington DC.
But Dobson, now 65, is a modest man, and once he had discovered his
vocation - teaching physics at Beloit College, in Wisconsin - he felt no
need to drop dark hints about his earlier life. You could have taken any
number of classes at Beloit with Professor Dobson, until his recent
retirement, without having any reason to know that in his mid-20s,
working entirely as an amateur and equipped with little more than a
notebook and a library card, he designed a nuclear bomb.

Today his experiences in 1964 - the year he was enlisted into a covert
Pentagon operation known as the Nth Country Project - suddenly seem as
terrifyingly relevant as ever. The question the project was designed to
answer was a simple one: could a couple of non-experts, with brains but
no access to classified research, crack the "nuclear secret"? In the
aftermath of the Cuban missile crisis, panic had seeped into the arms
debate. Only Britain, America, France and the Soviet Union had the bomb;
the US military desperately hoped that if the instructions for building
it could be kept secret, proliferation - to a fifth country, a sixth
country, an "Nth country", hence the project's name - could be averted.
Today, the fear is back: with al-Qaida resurgent, North Korea out of
control, and nuclear rumours emanating from any number of "rogue
states", we cling, at least, to the belief that not just anyone could
figure out how to make an atom bomb. The trouble is that, 40 years ago,
anyone did.

The quest to discover whether an amateur was up to the task presented
the US Army with the profoundly bizarre challenge of trying to find
people with exactly the right lack of qualifications, recalls Bob
Selden, who eventually became the other half of the two-man project.
(Another early participant, David Pipkorn, soon left.) Both men had
physics PhDs - the hypothetical Nth country would have access to those,
it was assumed - but they had no nuclear expertise, let alone access to
secret research.

"It's a very strange story," says Selden, then a lowly 28-year-old
soldier drafted into the army and wondering how to put his talents to
use, when he received a message that Edward Teller, the father of the
hydrogen bomb and the grumpy commanding figure in the US atomic
programme, wanted to see him. "I went to DC and we spent an evening
together. But he began to question me in great detail about the physics
of making a nuclear weapon, and I didn't know anything. As the evening
wore on, I knew less and less. I went away very, very discouraged. Two
days later a call comes through: they want you to come to Livermore."

Livermore was the Livermore Radiation Laboratory, a fabled army facility
in California, and the place where Dave Dobson, in a similarly surreal
fashion, was initiated into the project. The institution's head offered
him a job. The work would be "interesting", he promised, but he couldn't
say more until Dobson had the required security clearance. And he
couldn't get the clearance unless he accepted the job. He only learned
afterwards what he was expected to do. "My first thought," he says
today, with characteristic understatement, "was, 'Oh, my. That sounds
like a bit of a challenge.'"

They would be working in a murky limbo between the world of military
secrets and the public domain. They would have an office at Livermore,
but no access to its warrens of restricted offices and corridors; they
would be banned from consulting classified research but, on the other
hand, anything they produced - diagrams in sketchbooks, notes on the
backs of envelopes - would be automatically top secret. And since the
bomb that they were designing wouldn't, of course, actually be built and
detonated, they would have to follow an arcane, precisely choreographed
ritual for having their work tested as they went along. They were to
explain at length, on paper, what part of their developing design they
wanted to test, and they would pass it, through an assigned lab worker,
into Livermore's restricted world. Days later, the results would come
back - though whether as the result of real tests or hypothetical
calculations, they would never know.

"The goal of the participants should be to design an explosive with a
militarily significant yield," read the "operating rules", unearthed by
the nuclear historian Dan Stober in a recent study of the project
published in the Bulletin of the Atomic Sciences. "A working context for
the experiment might be that the participants have been asked to design
a nuclear explosive which, if built in small numbers, would give a small
nation a significant effect on their foreign relations."

Dobson's knowledge of nuclear bombs was rudimentary, to say the least.
"I just had the idea that \[to make a bomb\] you had to quickly put a
bunch of fissile material together somehow," he recalls. The two men
were assigned to one of Livermore's less desirable office spaces, in a
converted army barracks near the facility's perimeter. Bob Selden found
a book on the Manhattan Project that culminated in America's development
of the bomb. "It gave us a road map," Dobson says. "But we knew there
would be important ideas they'd deliberately left out because they were
secret. This was one of the things that produced a little bit of
paranoia in us. Were we being led down the garden path?"

They faced one key decision, Dobson says: whether to design a gun-style
bomb, like the one dropped on Hiroshima, that used a sawn-off howitzer
to crash two pieces of fissile material together, or a more complex
implosion bomb, like that dropped on Nagasaki. By now they were
beginning to enjoy the challenge, so they went for the harder, more
impressive option. "The gun device needed a large amount of material,
and didn't make a very big bang," Dobson says. "The other one was more
bang, less material."

Dobson and Selden had decided to assume that their fictional Nth Country
had already obtained the requisite plutonium - a huge assump tion, since
it would be, almost certainly, the hardest part - but there was plenty
more to consider. "Obtaining the fissile material is really the major
problem - that drives the whole project," says Selden. "But the process
of designing the weapon - I'm always careful to point out that many
people overstate how easy it is. You really have to do it right, and
there are thousands of ways to do it wrong. You can't just guess."

As Stober's study noted, the two amateurs were ironically aided by
information published as part of President Dwight Eisenhower's "Atoms
for Peace" program, which spread word of the benefits of non-military
nuclear power around the world. And Atoms for Peace was only the most
prominent example of a fad for everything nuclear that propelled a huge
amount of technical detail into the public domain.

Eventually, towards the end of 1966, two and a half years after they
began, they were finished. "We produced a short document that described
precisely, in engineering terms, what we proposed to build and what
materials were involved," says Selden. "The whole works, in great
detail, so that this thing could have been made by Joe's Machine Shop
downtown."

Agonisingly, though, at the moment they believed they had triumphed,
Dobson and Selden were kept in the dark about whether they had
succeeded. Instead, for two weeks, the army put them on the lecture
circuit, touring them around the upper echelons of Washington,
presenting them for cross-questioning at defence and scientific
agencies. Their questioners, people with the highest levels of security
clearance, were instructed not to ask questions that would reveal secret
information. They fell into two camps, Selden says: "One had been
holding on to the hope that designing a bomb would be very difficult.
The other argued that it was essentially trivial - that a high-school
science student could do it in their garage." If the two physics
postdocs had pulled it off, their result, it seemed, would fall
somewhere between the two - "a straightforward technical problem, but
one that involves some rather sophisticated physics".

Finally, after a valedictory presentation at Livermore attended by a
grumpy Edward Teller, they were pulled aside by a senior researcher, Jim
Frank. "Jim said, 'I bet you guys want to know how it turned out,'"
Dobson recalls. "We said yes. And he told us that if it had been
constructed, it would have made a pretty impressive bang." How
impressive, they wanted to know. "On the same order of magnitude as
Hiroshima," Frank replied.

"It's kind of a depressing thing to know, that it could be that easy,"
Dobson says. "On the other hand, it's far better to know the truth." And
the truth today, he is certain, is that terrorists - with a bit of luck
and, crucially, access to the right materials - could easily build a
nuclear bomb. "Back in the 50s, there were two schools of thought - that
the ideas could be kept secret, and that the material could be locked
up. Now? Well, hopefully the materials can still be locked up, but we
all have our doubts about that." Obtaining sufficiently enriched fissile
material could be difficult but, when it comes to creating the bomb, "It
turns out it's not overwhelmingly difficult. There are some subtleties
that are not trivial ... but an awful lot has been published. If you
were a grad student today, and you reviewed the literature, a lot of
pieces would fall into place."

It was, relatively speaking, easy - so easy that both Selden and Dobson
seem to have emerged from the Nth Country Experiment deeply troubled by
their own capacities. Selden stayed in the military, on a career that
sent him from Livermore to the army's other major research base, at Los
Alamos, and is still a member of the US Air Force Scientific Advisory
Board; he has been closely involved in planning how the US might respond
to a nuclear terrorist incident. Dobson, meanwhile, felt so
uncomfortable that he left the sector entirely. "It was one thing to
work on a project which was hopefully going to illuminate the decision
makers so they could see that weapons were easily designed," he says.
"It was a rather different thing to go in and say, 'OK, for example,
let's make a thermonuclear device that's only four inches in diameter.'
That's an acceleration of the arms race, and I didn't really want to do
that."

Einstein was famously said to have commented that if he had only known
that his theories would lead to the development of the atom bomb, he
would have been a locksmith. Dave Dobson, having designed one, got a job
as a teacher.