Saturday, August 9, 2014

"The Speck Of Matter God Had Not Welcomed At Creation..."


Today marks an anniversary of the Nagasaki atomic bombing by the so-called "Fat Man." Many forget that we dropped two kinds of atomic bombs in the span of three days in 1945: the first, "Little Boy," contained all of our laboriously accumulated U-235; its design was so simple it didn't need testing: Fire one subcritical U-235 mass at another U-235 subcritical mass and blammo! --  the whole thing went nuclear.

The second was a plutonium bomb -- and its design was so radical that it had to be tested first, hence "Trinity" at Yucca Flats.

The bomb makers knew early on that U-235 would be the limiting factor: only 1/140th of any uranium source was useable for a bomb. The rest was the unusable U-238 isotope. But the eggheads (really a who's who of nuclear physicists and chemists) figured out that nuking the otherwise useless U-238 with cyclotron radiation would transmute that useless uranium into heavier elements. Thus began a series of top secret experiments at Berkeley which extended the Periodic Table one element at a time.  That sort of work still continues.

First came element 93, the very first transuranic element, now known as neptunium, and synthesized by Edwin McMillan and Philip H. Abelson in 1940. That element proved unusable as a fissile material, so the search for the next heavier element continued. The work quickly became a rather dirty job -- separating the toxic gemischt into identifiable components --and one more suited for chemists. Glenn T. Seaborg, and a graduate student, Arthur C. Wahl, did the yeoman's work. By early 1941, they knew that they had something new, but were unable to separate it from co-produced thorium.  Seaborg and Wahl pressed on, working in a cramped third floor laboratory in the chemistry department at Berkeley. Success followed and by early March, 1941 Seaborg recorded:
With this final separation from thorium, it has been demonstrated that our alpha [particle] activity can be separated from all known elements and thus it is now clear that our alpha activity is due to the new element with atomic number 94. 
Within weeks, and after gathering enough material, tests showed that element 94 was fissile -- bomb material. He was already way ahead of anyone else. It was immediately apparent that chemical separation of elements was easier than isotopic separation, and element 94 production became a second major project in the Manhattan Project, running in parallel to uranium isotope separation.

Richard Rhodes wrote in his incomparable "The Making Of The Atomic Bomb:"
Not until 1942 would they officially propose a name for the new element that fissioned like U-235 but could be chemically separated from uranium. But Seaborg already knew what he would call it. Consistent with Martin Klaproth's inspiration in 1789 to link his discovery of a new element [uranium] with the recent discovery of the planet Uranus and with McMillan's suggestion to extend the scheme to Neptune, Seaborg would name element 94 for Pluto, the ninth planet outward from the sun, discovered in 1930 and named for the Greek god of the underworld, a god of the earth's fertility but also the god of the dead: plutonium. 

11 comments:

virgil xenophon said...

Did you make the usual memorial toast to the event today by drinking warm sake to celebrate? lol

XRay said...

Really like the science posts, chick. As there is so much I don't know. Read/subscribed to SciAm for thirty years till they turned to shit 15 or so years ago. Of course I usually didn't understand much after the first several paras, being a HS dropout an all, but found it all extremely interesting nontheless. I appreciate your time taken to deliver us some nuances.

XRay said...

virgil that was a cruel remark... I like it. Perhaps the start of a new tradition.

virgil xenophon said...

xray/

Been doing it on the 5th (Hiroshima) and 9th since, hell, at least 1976. Someone made the casual drunken suggestion and, well, you know how those things can go, bingo, you turn around and you realize you've got a 40-yr tradition..

edutcher said...

Just about anybody in the US Armed Forces would have been in on the campaign.

That speck of matter saved a lot of lives. Far more than, until a few years ago, most of us ever knew.

virgil xenophon said...

Did you make the usual memorial toast to the event today by drinking warm sake to celebrate? lol

Accompanied by Simon Buckner's, "May you walk in the ashes of Tokyo"?

Christy said...

And then in the early '70s a naturally occurring U-235 reactor from a couple of billion years ago was discovered in Gabon. Plutonium-239 decay products (it has been roughly 7000 plutonium half-lives, after all) were in evidence. So God did create transuranics.

Christy - Queen of the Pickers of Nit

Postscript - a pal once threw annual Get Bombed on Pearl Harbor Day parties. Poor taste, wonderful party. He always cooked a ham, a tribute to Hawaii's fondness for Spam, perhaps?

bagoh20 said...

The satisfying thing about discussions in the hard sciences is the presence and acceptance of a foundation of fact that is testable, reliable, and rarely tossed aside unless something truly superior is found, which then is accepted as such.

It is so frustrating to talk politics or law where even the basic fundamentals are not agreed on, and where ignoring those that do exist is part of every discussion. If this science post was handled the same way, I would step in here and claim that the idea of a nucleus and orbiting electrons is invalid because it stems from a patriarchal idea based on imperialism and also that fission is a violent fantasy dreamed up by dead white guys before the enlightenment of the 60's.

That said, I'll drive us off the road into the political fog with this: Imagine if the situation of 1945 occurred under current political restraints. I can't imagine the bombs being dropped by us today. There existence would never be revealed, the war would have ended in a stalemate after many deaths on both sides, but probably not the millions of an invasion victory. Is that better or worse?

The Dude said...

Obama would drop the bomb, but only on Americans with whom he disagrees.

He has weaponized the federal government and it is just a matter of time until all the munitions they have stockpiled will be unleashed against what used to be citizens, but are now viewed as uncooperative subjects.

Bumps in the road.

rcocean said...

The Manhattan project was much more that the Physicists. There was a lot of Chemists and Engineers who's work was critical. The theoretical had to turned into the practical. In fact, Teller got so bored, he started to work on the H-bomb.

chickelit said...

I should have emphasized that in 1940, element 92 was the absolute end upper limit of the Periodic Table. The end. Fini. There wasn't anything heavier known.

After Seaborg's group got rolling post-war, the next element after Plutonium was named Americium, then Curium and then back to Berkelium and Californium. At the time that the latter two were named, The New Yorker sarcastically remarked that the Berkeley group had missed an opportunity by not naming the prior two elements "Universitatium" and "Ofium" first.

chickelit said...

Christy wrote: Christy - Queen of the Pickers of Nit

Your comment is actually pretty astute.

Seaborg got composition of matter patents through the US PTO for at least one transuranic elements -- Americium -- which is used in smoke alarms. HadAmericium been found in Nature then his patent should be void.