Posts Tagged ‘Fat Man’

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Soviet drawings of an American bomb

Friday, November 30th, 2012

The United States government is pretty gun-shy on publishing drawings of nuclear weapon designs, even very crude ones. When it comes to implosion bombs, this is about all that’s allowed to come out of official sources:

From the 1977 edition of Glasstone and Dolan’s The Effects of Nuclear Weapons. “Then explodes” puts it a little mildly, I think.

Not extremely informative — a ball-within-a-ball — and a heck of a lot less information than you can find from other sources. The reasons for this are ostensibly based in security — terrorists, enemy powers, etc. — though I tend to suspect they are based in the fear of scandal more than anything else. Congressional oversight gets itchy when they see something that looks like a “bomb-making guide,” even when it is well-within the limits of security.1 (The basic implosion idea was declassified in 1951 as part of the Rosenberg trial, though there were knowledgable people arguing for it as early as 1945.)

I find the level of abstraction allowed in such drawings to be a little ridiculous, especially when far more detailed technical information is actually declassified. For reasons that I suspect are deeper than mere policy considerations alone, you can write a lot of things down that you can’t draw, if you’re someone with an actual security clearance. This isn’t totally nonsensical: drawings can make immediately clear lots of things that can otherwise hide in technical descriptions, which is one of the reasons that putative drawings of nuclear weapons are one of the topics that originally drew me to the topic of nuclear secrecy.

We aren’t really talking about blueprints here — these things aren’t usually to scale, they aren’t designed for engineers to use. Even if we were talking about blueprints, there are still quite a few steps in between a drawing of a thing and the thing itself. Drawings of this sort could certainly help an incipient nuclear program, but only in the sense that they can guide research questions or general directions. A drawing of an atomic bomb is not an atomic bomb.

But even though the US is fairly tetchy about its bowdlerized bomb drawings, it does better than most other nuclear states. The United States actually publishes things about their nuclear programs. Though the US has a well-deserved reputation for secrecy, they also have put out tons and tons of technical and non-technical information about how their bombs work(ed), how bombs in general work, technical details about the weapons themselves, and so on. Why? It’s a legacy, perhaps, of the Smyth Report, Atoms for Peace, and other gestures towards the positive role that nuclear information can play in the public sphere.

Ah, but there is one exception: post-Soviet Russia. The people working at Rosatom, the Russian state nuclear agency/corporation, have been publishing impressive amounts of raw historical documents information about the Soviet bomb project, as part of their on-going series Atomnyi proekt SSSR/Атомный проект СССР/USSR atomic project. The series started in 1998, and the early volumes have gotten a lot of good scholarly attention by folks like Alexei Kojevnikov and Michael Gordin, but only very recently did I find that they’ve been still publishing them, and from what I can tell, the newer volumes have not been used too much. The most recent volume that I’ve heard of — volume 3 — was published in 2009. Getting ahold of them is another matter altogether; in the United States, anyway, they’re devilishly hard to find to purchase, and even on Russian websites they are pretty rare. The Library of Congress has the first two volumes in their entirety, and I think I’ve found a source for purchasing the third (supposedly it is on its way), but not without some effort.

Here, for example, is the sort of drawing that the Russians declassified and published in one of the 2007 volumes:

Nuke aficionados will recognize immediately that this is a pretty good drawing of an implosion bomb, especially when compared to the ball-within-a-ball. The labels are pretty straightforward: A– detonator; B– explosive lens (1–Comp. B outer lens, 2–Baratol cone, 3–Comp. B inner lens); C–cork lining; D–aluminum pusher; E–uranium tamper; F–boron plastic shell; G–the Po-Be initiator. The only weird part is that they didn’t label the actual plutonium core itself (the cross-hatched sphere that surrounded the G sphere), but I guess it went without saying. Note also that they’ve indicated how the core can be added in after-the-fact with the removable “trap door” pusher. That’s one of those nice little touches that says, “I am not merely trying to explain an abstract concept, I’m trying to tell you how we might build one of these things.”

But more awesome than the drawing itself — which you can, incidentally, get on a T-shirt, if you’re interested and go for that sort of thing — is its source. It’s from the Soviet archives, part of a report dated January 28, 1946, titled “Notes on the design of the atomic bomb: Description of the construction of the ‘explosion inside‘ type bomb.”2 Get it, “explosion inside”? They hadn’t even formalized their terminology for “implosion” yet and were using a scare-quoted, made-up word in the meantime. As the report makes clear, this is a Soviet description of the American atomic bomb detonated at “Trinity,” based on intelligence received from Soviet spies at Los Alamos. (Other reports refer to Klaus Fuchs directly by name, though I’m not sure if the people drawing up this particular report knew he was the source.)

There is no way in heck that the American government would ever allow the release of so “detailed” a drawing from any source that had access to classified information. Granted, it’s a long way from being a “blueprint” — something the drawing itself acknowledges; the text at the bottom reads “schematic drawing, not to scale” — but it’s still the sort of thing that no weapons lab would want a Congressperson to see them handing out, much less publishing widely. But apparently Rosatom is not as burdened by this — when it comes to publishing pictures of American bombs, anyway!3

Here’s another fan-favorite — a series of drawings breaking the final assembled “Fat Man” bomb into its constituent parts, showing how they call go together, IKEA-style (click any of them to zoom):

The outer casing and the placement of the bomb within it. The caption at bottom says, “Bomb used on Nagasaki (Total weight 10,500 pounds – 4,650 kilograms).” I’m having trouble making out the “note” at the top left but it is seems to be saying something is tentative about the drawing.

The first four “spheres”: 1–initiator, 2–plutonium, 3–tamper, 4–aluminum pusher. Note that the publishers have omitted the exact measurements and replaced them with ellipses. <s>It seems to indicate that the plutonium core is in “3 parts,” which jibes with an earlier post of mine (and indicates that the intelligence source really knew what he was talking about, not that we didn’t already know that).</s> Actually, as is pointed out in the comments, if I had continued translating, I’d see that it says the plutonium must have impurities of only 3 parts per million. Still, a nice little detail.

Spheres 5 and 6: a layer of 32 blocks of chemical explosives, and then a layer of 32 blocks of explosive lenses. The detonator is labeled as a “booster” in English, oddly enough.

Sphere 7: the duraluminum casing, with “holes for detonators.” Comrade Beria likes his details! Compared with the Trinity Gadget.

Lastly, the overall arrangement of the bombs within the casing itself, with its electrical and detonating systems indicated. (You’ll perhaps recognize the first and last images here from another post I did, awhile back, as they are reprinted in a tiny form in another source.)

It’s a veritable nuclear Matryoshka doll, is it not? I wish I could make this stuff up, but I can’t. My favorite part about this document, though, is the fact that so much of the captions are in English — again, as if any indication were needed about where this information was coming from. The document itself was written by Igor Kurchatov for Lavrenty Beria, dated June 4, 1946.

There isn’t anything remotely like a security threat here — you can get better drawings on Wikipedia these days, without the numbers redacted — but to have stuff like this published by an actual nuclear power, based on data they derived in the course of making their own atomic bomb, data taken from a source working in a weapons lab… well, let’s just say, I don’t think it’s going to happen over here anytime soon.

Still, the drawings do have a talismanic power, and the Mandala-like quality of the implosion design doesn’t hurt that. It’s the bomb, right? And yet, it’s really not. It’s a drawing. A technically crude one, albeit more detailed than the other “official” releases. It’s no surprise, I suppose, how easily we get sucked in by the superficially technical — whether it carries any real power or not.

Notes
  1. See, for example, page 70 of chapter 2 of the Cox Report, which criticized Los Alamos for releasing exactly this kind of heavily-sanitized information. [↩]
  2. Заметки о конструкции атомной бомбы. Описание конструкции бомбы типа “взрыва вовнутрь.” [↩]
  3. This reminds me of a joke from the Brezhnev-era USSR that a Russian teacher of mine told me: During a visit to the United States, Premier Brezhnev and President Carter happen to see a protest. “No Carter, No Reagan!” the protesters shouted. “You see,” said Carter, “in our country we have freedom of expression, something you don’t have over in your country.” “Ah, Comrade,” says Brezhnev, “you are wrong! Come over and see!” So they go to Red Square, and indeed, there is a mob of protesters forming, shouting, “Nyet Carter, nyet Reagan!” [↩]

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Forbidden spheres

Wednesday, August 29th, 2012

Spheres are special shapes for nuclear weapons designers. Most nuclear weapons have, somewhere in them, that spheres-within-spheres arrangement of the implosion nuclear weapon design. You don’t have to use spheres — cylinders can be made to work, and there are lots of rumblings and rumors about non-spherical implosion designs around these here Internets — but spheres are pretty common.

A photograph of a rather suspicious sphere-within-a-hemisphere, from the inside of Israel’s secret nuclear site, Dimona, taken by Mordechai Vanunu in 1986.

Spheres also happen to be fairly common sights in the non-nuclear weapons design as well. What interests me is what happens when you take a perfectly non-nuclear sphere, like, say, a soccer ball, and move it into a nuclear context. To the trained eye, it takes on a rather interesting new meaning:

Image from the cover of A.Q. Khan on Science and Education.

Presumably Dr. Khan was not using the ball above to express his love of sport, but instead was using it to convey in broad terms what the truncated icosahedron shape has to do with implosion weapons — it is the geometry of the explosive lenses used in the Trinity “gadget” and “Fat Man” bomb designs, similar to the one sketched on the upper-right side of the chalkboard above.

(I will just also note that somebody — presumably not Dr. Khan himself, but who knows — has rendered in chalk a truly excellent reproduction of figure 2.07a from Glasstone and Dolan’s Effects of Nuclear Weapons, 1977 edition.)

All of which is to say that spheres are important from a nuclear point of view, and the context of spheres can change their meaning dramatically. Nothing too surprising or controversial there, I hope.

Such is the background I want you to be thinking of when you read the below line item from the notes of a Technical Board Meeting at Los Alamos, from May 1947.1

8. The Director [Norris Bradbury] asked for an expression of opinion as to what might be the difficulties that would arise if he asked that all possibly revealing shapes in the various Tech offices be removed. For example, spherical ash trays and such things that are not actually bomb parts or models, but cause security people concern because they feel that the presence of such items makes security policing difficult. It was agreed that the Director would bring this up at the next colloquium.

Imagine the scenario: you’re a security officer working at Los Alamos. You know that spheres are weapon parts. You walk into a technical area, and you see spheres all around! Is that an ashtray, or it is a model of a plutonium pit? Anxiety mounts — does the ashtray go into a safe at the end of the day, or does it stay out on the desk? (Has someone been tapping their cigarettes out into the pit model?)

You must admit, there’s a certain familial resemblance.

All of this anxiety can be gone — gone! — by simply banning all non-nuclear spheres! That way you can effectively treat all spheres as sensitive shapes.

What I love about this little policy proposal is that it illuminates something deep about how secrecy works. Once you decide that something is so dangerous that the entire world hinges on keeping it under control, this sense of fear and dread starts to creep outwards. The worry about what must be controlled becomes insatiable — and pretty soon the mundane is included with the existential.

I’ve posted this quote before, from Mordechai Vanunu’s lawyer, but it never gets old. Secrecy is contagious:

If something is secret, and something else touches it, it too becomes secret. Secrecy becomes a disease. Everything around the secret issue becomes secret, so the trial became a secret, so I became a secret.

So, did Los Alamos actually end up adopting the policy of No Spheres in the War Room? It may very well have! Below is an excerpt from Joseph Masco‘s highly-recommended book, The Nuclear Borderlands: The Manhattan Project in Post-Cold War New Mexico:

One weapons scientist explained to me how he breached security at Los Alamos simply by bringing a sack lunch into the plutonium facility. He left his lunch on his office desk and stepped out for a minute. He came back to find a commotion. A security officer informed him that the orange he left on his desk was, in fact, a classified object.

He learned that any spherical object became a nuclear secret once it passes over the line demarcating the secure from the open areas of the laboratory, as it could be taken as a model for the plutonium pit that drives a nuclear weapon.

The weapons scientist was told that in the future he could eat the fruit or store it inside his office safe with the rest of his classified documents, but if he left the orange out on his desk unsupervised it was a security infraction that could be referred to the FBI for investigation.

Truth, rumor, exaggeration? A distinction that’s not mine to know. But it’s still pretty amusing. One wonders how many “inappropriate lunch” cases the FBI has to investigate.

Image source: floating around the Internet.

I’ve asked some contacts I have at Livermore if they had such a policy out there, and they said they hadn’t heard of one. But maybe they’ve just never made the mistake of bringing a sphere to lunch. 

Notes
  1. Citation: Los Alamos Technical Board Notes (2 May 1947), copy in Chuck Hansen papers, National Security Archive, George Washington University, Washington, D.C., Box 51, “U.S. Nuclear Testing Program, 1944-1947, 1959.” [↩]

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Visions

Going Back to Tinian

Friday, August 24th, 2012

In my last post, I talked about what the island of Tinian was like in World War II, when it served as the launching point for strategic bombing raids on Japan — including the bombings of Hiroshima and Nagasaki.

A physicist friend of mine from graduate school, Alex Boxer (who currently consults the Navy about submarines, and has his own history of science blog), recently took a vacation to Tinian, and took a ton of photographs. He’s given me permission to re-print some of them here, along with some of his comments on them (which are in italics).

You can begin your virtual tour of Tinian with this movie of what it’s like to fly there from Saipan.  The planes are just little 6-seater prop-planes, and the flight is probably a grand total of 10 minutes.  In this movie (sped-up 2x to reduce its size) you can see the whole island and what’s left of the North Field runways.

There’s very little to see that’s bomb-related — it’s striking, really, it’s almost as if the US military was never there.  The only buildings which remain from that era are Japanese installations.

A random Japanese propeller located on the southern end of the island:

At North Field (located, sensibly enough, at the North end of the island) there are several Japanese buildings:

Description from a placard outside the building:

This two-story building was the World War II headquarters of the Japanese Navy’s 1st Air Fleet (Base Air Force of the Marianas), commanded by Vice Admiral Kakuji Kakuta. … Admiral Kakuta’s airfields in the Marianas and Iwo Jima served as staging areas for moving aircraft to southern Pacific battle areas and for attacks on American ships. By July of 1944, the airfields directed from the 1st Fleet headquarters had been captured or destroyed. What remained of Admiral Kakuta’s airplanes was destroyed in the naval battle of the Philippine Sea a month before the battle of Tinian. … When Americans captured Ushi Field, the headquarters building was abandoned and Ushi Field was a “ghost field” of abandoned airplane wrecks. The fate of Vice Admiral Kakuta is unknown, but was probably suicide or death. His last radio message to Tokyo was on July 30 as the battle of Tinian was nearing its conclusion. The massive concrete headquarters building was damaged by American artillery, but the building was repaired and used by American military officers after the invasion.

Another placard:

This building was the control center for the Japanese Navy’s 1st Air Fleet operations on Tinian, directing traffic on the runway to the south. It contained an office, the operations room, and a generator room. This is a standard design for World War II Japanese air operations buildings, with other examples located on Saipan and Chuuk. … The building was repaired and used as a control tower by the 20th Air Force after the B-29 runways of North Field were constructed here.

One more placard:

This massive power plant was probably build in 1939-1940 as part of the Japanese military construction of Ushi Field. the “bombproof” building was constructed of reinforced concrete and had steel shutters covering the windows. The building housed a 200 kilowatt power plant run by diesel fuel.

 And here’s what you’ve been waiting for: bomb-pits! — The pits where Little Boy and Fat Man were loaded into the B-29s that dropped them on Japan.

I was somewhat dismayed at how little there was to see.  It’s just two pits now under glass enclosures, somewhat like the entrance to the Louvre.  The glass was also highly reflective which means that most of my photos didn’t come out very well.

The loading pit is under the glass enclosure.

Tinian was fantastic because it was one of the emptiest and quietest places I’ve ever been.  I felt like I had the whole place to myself.  However, there is nominally a tourist industry there which includes a rather shady hotel/casino.  The tourists are mainly from Asia and Russia — there’s hardly anyone from the mainland US (a brief look at a map of the Pacific will make it clear why this is so).  Anyways, our silent day was enlivened by a large tour-bus.  I’m certain that these tourists are not Japanese; I’m almost, but not quite 100% certain that they are Chinese.

Interjection: just to compare, here are the actual loadings of Little Boy and a Fat Man test unit.

Or you could fly all the way to Tinian, and see the same sort of photos in the actual bomb pit:

Back to Boxer:

And as much as I’m an aficionado of atomic (or, rather, nuclear?) history, that wasn’t the main lure for me.  Here’s what I really wanted to see on Tinian:

These are parts of the House of Taga:

The site is the location of a series of prehistoric latte stone pillars which were quarried about 4,000 feet south of it. Only one pillar is left standing erect. The name is derived from a mythological chief named Taga, who is said to have erected the pillars as a foundation for his own house. Legend says Chief Taga was murdered by his daughter, and her spirit is imprisoned in the lone standing megalith at the site.

I have to admit, I wasn’t aware that the only other tourist site on Tinian was just about as grim at the first atomic bomb loading pits.

And, just for fun, here’s a lovely photo of a Flame Tree:

Very cool. Let’s all give a little round of virtual applause for Dr. Boxer and maybe visit his website while we’re at it.

Now, you might be thinking — well, Tinian’s heyday has come and gone. And you might be right. But there’s been some interesting news about it from earlier this year:

Japan Self-Defense Forces officials will arrive today to discuss with CNMI officials their plans for Tinian where two-thirds of land are already leased by the U.S. Department of Defense, and the discussions could center around Japan’s plan to help fund a U.S. military base on Tinian or the training or stationing of their own forces there.

That’s right — there’s a chance (perhaps not a great one) that Tinian might yet be the site of a military base. What would be more appropriate — or inappropriate? — than Tinian becoming a joint US-Japanese military site?

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The Hiroshima Do-Over (1963)

Wednesday, May 16th, 2012

As everybody knows, the bombings of Hiroshima and Nagasaki were the only instances of actual combat detonations of nuclear weapons. The victims of the bomb — the Hibakusha — were also the one-and-only direct human test subjects on the effects of the bomb. This grim connection between victims and experimental subjects runs through quite a bit of the scientific literature on nuclear health.

A doctor working for the Atomic Bomb Casualty Commission examines a Hibakusha in the postwar period.

After World War II, the US sent over physicians and specialists to find out as much as they could on the survivors of the atomic bombs. Japanese physicians were of course already doing this themselves. This work was eventually consolidated into the Atomic Bomb Casualty Commission.

Starting in the mid-1950s, when the US government became concerned about Civil Defense against atomic bombs, scrutiny of radiation data from Hiroshima and Nagasaki became a major preoccupation. What exactly was the radiation output of the Hiroshima and Nagasaki bombs? Nobody knew. They hadn’t really kept as good tabs on that as they perhaps ought to have. Oppenheimer, Groves, et al., hadn’t even really thought that much about the radiation effects before dropping the bombs.1

The Nagasaki bomb, at least, was an implosion model, and these had been not only continued to be tested after the war (the Operation Crossroads weapons were essentially Fat Man devices), but were the subject of on-going interest and development. The Hiroshima bomb, Little Boy, was a model that was obsolete even as it was being dropped. (Literally: Oppenheimer proposed to Groves that they abandon it; by removing all of the HEU inside the single Little Boy bomb, they could make half a dozen HEU-fired Fat Man bombs.) Nothing terribly similar to the Little Boy bomb would ever be dropped again (only four gun-type devices were ever detonated, ever, and the later ones — one W9 and two W33 tests — were different enough that their radiation spectrum was probably not the same).

One way that you could carefully measure the radiation output of the Little Boy bomb would be to test another one — say, out in the Nevada desert. In 1963, Norris Bradbury, director of Los Alamos, wrote out exactly why he thought this would be a bad idea. “ The periodic proposal to refire the Hiroshima and Nagasaki bombs is air over Nevada or somewhere to measure their radiation in great detail appears to have arisen again,” Bradbury wrote, and then enumerated a number of reasons against it.2

Click to view PDF.

First on the list is the fact that by 1963, the United States had signed the Partial Test Ban Treaty, barring any kind of nuclear tests in the atmosphere. So the possibility of detonating an old Little Boy bomb in the atmosphere “has about the chance of a snowball in you know where,” wrote Bradbury. (Why not underground? Bradbury doesn’t say, but elsewhere I’ve seen it pointed out that the entire point of such an exercise would be to understand the radiation in the atmosphere. Doing it underground would involve a lot of fudging, apparently.)

Second on the list was the difficulty of putting together fair replicas of the 1945 bombs. While parts of the Nagasaki bombs could probably be rustled up, “new X-units would be required,” (the X-unit was the firing electronics), and “the different X-unit would certainly cause some difference in the radiation spectrum and distribution.” Put another way, they just didn’t have exact replicas of the Little Boy and Fat Man bombs by 1963. Bradbury offers up that the Mark-6 bomb would probably be pretty close to the Nagasaki bomb. “LASL is not repeat not going to make a replica of the Nagasaki bomb in this day and age for this type of purpose. It is worth neither the time nor the effort. If a MK 6 will not do — then forget it.”

Third on the list is related specifically to the Little Boy bomb: “We could probably make a reasonable replica of the Hiroshima device. Some old LBs probably exist in part. They are unsafe (remember Parsons‘ famous bomb bay insertion of the active material?) and some type of safing would have to be dreamed up.” Bradbury earlier describes these old weapons as being “hideously unsafe.” He concludes that the differences between a Little Boy replica and the actual one would not be as big as between the Mark 6 and the Fat Man, but the differences “will take time and effort to work out.”

Lastly, he laid out exactly how much of a bad idea he thinks it was:

Unless these experiments are likely to be real, we see no reason to give much more than idle speculative effort thereto and do not [sic] real work. Let us not kid ourselves — making these devices and shooting them is going to be real work and totally unproductive work from the standpoint of weapon development. In my personal opinion, although doubtless based more on emotion than on scientific reason, the experiments will add little of practical utility in the high level dose rate area anyway. What does one do with the information when (and if) one has it? Some people get exposed at some level and die; some do not; some get malignancies; some do not. That will remain true whether we know the MLD 50 to 5, 10 or 50 Roentgens. Basically, with test money cruelly short and with testing philosophy cruelly restrictive why should we waste effort on this sort of thing?

One wonders what the cause of the “emotions” were. Dredging up memories of old and difficult work? Just a feeling that he was wasting time? Frustration with the atmospheric test ban? A lack of interest in the Hibakusha?

They never did re-test Little Boy. What they did do, some many years later, was create a replica.

Click on for more information about the Little Boy Replica, including pictures!

Notes
  1. Sean Malloy has a fascinating article about this coming out in Diplomatic History next month; I am writing something up on it to share then as well. [↩]
  2. Citation: Norris Bradbury TWX to A.W. Betts (2 January 1963), copy in Nuclear Testing Archive, Las Vegas, NV, document NV0102280. [↩]

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The Censored Chapter (1946)

Wednesday, May 2nd, 2012

An article of mine (“A Tale of Openness and Secrecy: The Philadelphia Story”) has recently been published in Physics Today. Even better, the article has been made available for free on the Physics Today website (and as a PDF), so it can be read widely.

Click to go to the article online.

The basic story is thus: in late 1945, a group of scientists at the University of Pennsylvania, led by one William E. Stephens, decided that it would be a really cool thing to write their own, heavily-technical version of the Smyth Report. They would show that a bunch of non-nuclear physicists could, from the published literature and first principles, explain in technical terms exactly how atomic bombs worked. By publishing this, they’d prove that there wasn’t any “secret” to the atomic bomb at all. But what started out as a statement about the futility of scientific secrecy quickly became a test of the limits of free discourse in the nuclear age.

These scientists were the unheralded predecessors of the Howard Morlands, Chuck Hansens, Carey Sublettes, and John Coster-Mullens of the world, but their story is basically unknown today, despite having lasting effects on the way that the postwar Manhattan Project and Atomic Energy Commission thought about secrecy. Their original goal — to show that clever outsiders could guess at secret things — definitely came across to the atomic officials, even if their denunciation of secrecy did not.

The final book was published as Nuclear Fission and Atomic Energy in late 1948 (two years after it was first written), and is now completely out of copyright. It’s not an interesting read, on the whole, though the forward and preface are interesting in respect to the purpose of the volume.

But the published version is missing part of the chapter on nuclear weapon design — the part that was “voluntarily” censored at the request of the Manhattan Project and AEC. The reason it was censored was because the scientists had managed to independently derive the idea of implosion. The implosion design (which was used in the Trinity “gadget” and the Fat Man bomb) was still considered secret at the time (it wasn’t declassified until 1951), so this was a pretty big coup on their part.

This week’s document is a true exclusive: the censored chapter from Nuclear Fission and Atomic Energy, taken from the AEC’s files. Stuck into the chapter was a note by William Waymack to Robert Bacher (AEC Commissioners both) decrying how irresponsible they felt the scientists were. (It is quoted, and partially photographed, in the Physics Today article.)1

Click the image for the PDF.

Everything from section 11.6 onward was cut from the final book (as can be seen from the Archive.org version of the book, linked to above). It’s the only part of the volume that was so censored, but it ends the chapter quite abruptly. I’ve marked the point of censorship in the PDF above.

It’s not a thrilling read — it is heavy on the math — except for the fact in that it actually talks about implosion (by name!) which is pretty big bananas for a bunch of scientists with no Manhattan Project connection in late 1945. The fact that they mentioned it by name was considered a particular indictment by MED and AEC officials — though they pointed out that it was a common technical term and was present in every decent dictionary.

The fateful word.

If there are any technical people reading, I’d love to know what you think about their reasoning here. I suspect it is actually not that great — that other than getting the general implosion concept, it is probably more revealing of their ignorance than their knowledge — but I’m not a technical person, so I don’t really know. My feeling is that while the point that trained scientists can independent re-derive and re-discover scientific “secrets” is largely correct, you probably can’t do it very well from a purely theoretical standpoint. (To their credit, the physicists admit this, especially when talking about critical mass estimates, since they could tell from the Smyth Report that so much hinged on getting very good neutron cross-section measurements.)

Some parting intrigue: the Library of Congress has a copy of this early draft as well in its main holdings… but  somebody has long since torn out the pages in question. Spooky! I suspect the FBI — they were sent around in 1948 to round up any missing copies of the book, and the AEC had been told about the copies on deposit at the LOC — but I’ve no hard evidence on it.

An addendum: Yesterday evening, I received an e-mail from William Stephens’ son, thanking me for writing the article. He added a detail I hadn’t any clue about. At one point in the story, the Pennsylvania scientists go to New York to give a press conference denouncing atomic secrecy. Stephens’ son was born while he was away — on the same day. I love that detail; it adds a personal touch to a story which is otherwise composed of letters and memos. (Look for some more thoughts along those lines on Friday.)

Notes
  1. Citation: Chapter 11 from William E. Stephens, ed., Nuclear Fission and Atomic Energy (draft June 1946), copy in Records of the Atomic Energy Commission, RG 326, National Archives and Records Administration, Records of the Commissioners, Office Files of Robert F. Bacher, Subject File, 1947-1949, Box 3, Folder “Philadelphia Story.” [↩]

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