The First War of Physics (21 page)

After a couple of aborted attempts during September, the Grouse party parachuted onto the Hardanger Plateau on 18 October 1942. They landed 30 miles from the designated drop zone. As Haukelid later remarked: ‘It was always curious to the Norwegians how incapable the British and American pilots were at navigating over mountains and forests. They were looking for towns, navigable big rivers, railroad lines, big electrical conduit lines, etc. In the Norwegian mountains there is only wilderness.’

Although the weather had been fine at the time of the drop, the Grouse party was subsequently hit by several storms and took fifteen days to trek to their base of operations close to the Mosvatn dam. ‘In good weather, it would have taken us a couple of days,’ Poulsson later said, ‘but because the snow was wet, the ground wasn’t frozen, the streams and lakes were open [ice-free], it took us one hell of a long time with all that equipment.’
⁹

The group made contact with Einar and Torstein Skinnarland and radioed their arrival back to the SOE on 9 November. On the same day Jomar Brun and his wife, who had fled to Sweden with the aid of Norwegian intelligence, boarded a plane bound for Britain. Three days later the advance party signalled that they had found a suitable landing site, three miles to the south-west of the Møsvatn dam.

The planning for Operation Freshman was finalised at SOE headquarters in Baker Street a few days later. Tronstad recommended that the attack be limited to the heavy water plant itself, which he believed could be put out of commission for up to two years. On 17 November, Grouse sent the following invitation:

Lake covered with ice and partly covered with snow. Larger lakes are ice free. Last three nights sky absolutely clear with moonlight. Temperature
about 23° Fahrenheit. Strong wind from the north has died down tonight. Beautiful weather.

Mountbatten advised Churchill on 18 November in a memo delivered via Cherwell. Churchill gave Operation Freshman a green light.

¹
After the war this group became known as
Kompani Linge
, named for its first leader, Captain Martin Linge, who was killed by a German sniper during a raid in December 1941.

²
Starheim was one of the first Norwegian resistance fighters recruited by the SOE. He was parachuted back into Norway in January 1942, charged with organising resistance in southern Norway together with his colleague Andreas Fasting, known by their codenames ‘Cheese’ and ‘Biscuit’.

³
The SOE was headquartered at 64 Baker Street in October 1940. As the organisation expanded it occupied 82 Baker Street and the top floor of 83 Baker Street situated across the road. The Baker Street Irregulars was the name of Sherlock Holmes’ fictional group of spies.

⁴
The 25 pounds of active material mentioned in the MAUD Committee report corresponds to a little more than 11 kilograms. The third National Academy report suggested that an explosive mass of U-235 between 2 and 100 kilograms would be required. This suggests that the German physicists understood the principles of an atomic bomb based on the physics of fast-neutron fission reactions.

⁵
Even without the mix-up, it is doubtful that such senior figures would have accepted the invitation. However, members of their various staffs did attend.

⁶
This was one of Göring’s favourite restaurants. He had exempted the restaurant staff from military service, receiving in return 70,000 bottles of port wine for the Luftwaffe.

⁷
The physicists had earlier discovered that powdered uranium metal is pyrophoric – it spontaneously catches fire on contact with air.

⁸
Wigner may have mis-remembered the warning that Houtermans had sent via Fritz Reiche the previous year.

⁹
Television survivalist Ray Mears recreated this trek for a three-part documentary series first broadcast by the BBC in 2003.

Chapter 7

THE ITALIAN NAVIGATOR

January 1942–January 1943

‘W
e’ll have the chain reaction going here [in Chicago] by the end of the year’, Arthur Compton declared from his sickbed on 24 January 1942. Ernest Lawrence bet him a thousand dollars that they wouldn’t.

‘I’ll take you on that’, Compton answered.

Lawrence backed off. ‘I’ll cut the stakes to a five-cent cigar’, he countered.

Compton, who had never smoked a cigar in his life, agreed.

The United States had been at war for just seven weeks. Compton had hastily pulled together a plan for the S-1 programme, and had reached a critical decision point just as he had gone down with influenza. The programme would follow the conclusions of the third and final National Academy report and focus on the problem of uranium isotope separation and the physics of a U-235 bomb. However, although the possibility of building an atom bomb using element 94 may have all but disappeared from the final Academy report, Compton had not forgotten it.

Compton’s principal task in the S-1 programme was to work on the physical principles of bomb design but, largely as an afterthought, he was also assigned the task of examining the potential for element 94. ‘Except
for this afterthought,’ he later wrote, ‘there might well have been no development of the nuclear reactor as a wartime project.’

From the beginning, the goal of the reactor project was understood to be the production of element 94. This was work that had to be consolidated in one location, and this was the decision that now confronted Compton. Szilard argued for Columbia University. Lawrence argued for Berkeley. Princeton and industrial laboratories in Pittsburgh and Cleveland were also considered. Compton advanced the case for Chicago. Like the Uranverein physicists in September 1939, nobody involved in the American programme wanted to relocate. Compton, who had already advised Conant that the work would be done in Chicago, exercised his executive authority. His bet with Lawrence was on.

Concern for secrecy led the laboratory at Chicago which was to house the project to be called the ‘Metallurgical Laboratory’, or just Met Lab, as deliberately obscure a name as MAUD and Tube Alloys. The only secret that Enrico Fermi’s wife Laura discovered about Met Lab during the war was that there were no metallurgists employed there. ‘Even this piece of information was not to be divulged’, she wrote. ‘As a matter of fact, the less I talked, the better; the fewer people I saw outside the group working at the Met Lab, the wiser I would be.’

According to Compton, Fermi agreed to the move from Columbia to Chicago at once. In truth, Fermi was reluctant. He and his small research team at Columbia had made significant progress with reactor configurations based on cubes of uranium oxide stacked in a lattice of graphite bricks. That they hadn’t succeeded in creating the environment for a self-sustaining chain reaction was put down largely to problems of impurities in their materials. Now the team was to be dispersed as the physicists joined different parts of the S-1 programme.

Fermi travelled back and forth to Met Lab before settling in Chicago at the end of April 1942. His wife Laura joined him at the end of June, having first retrieved the cache of Nobel prize money that Fermi had won in 1938 and hidden in a lead pipe under the concrete floor in the basement of their New York home. This had been insurance against the possibility that – as enemy aliens – their assets might be seized.

By the time Fermi was settled in Chicago, element 94 had finally acquired a name. In a report on the chemical properties of elements 93 and 94 dated 21 March 1942, Seaborg and Wahl had decided to name element 94
plutonium.
‘[W]e considered names like extremium and ultimium’, Seaborg wrote. ‘Fortunately we were spared the inevitable embarrassment that one courts when proclaiming a discovery to be the ultimate in any field by deciding to follow the nomenclatural precedents of the two prior elements … We briefly considered the form plutium, but plutonium seemed more euphonious.’

The report was typed by Lawrence’s secretary at the Rad Lab, Helen Griggs. ‘I like to say that she was so efficient as a secretary that I began to date her’, said Seaborg. ‘She doesn’t like that characterization, and I have to admit immediately that she had other qualities.’ Seaborg married Griggs in Nevada, on their way to Chicago.

Seaborg arrived in Chicago on his 30th birthday, 19 April 1942. If Fermi could get a reactor working before the end of the year, as Compton had wagered, then Seaborg’s task was to work out how plutonium could be separated from the spent reactor materials. His biggest problem was that he needed to understand the chemistry of this new element before a working reactor was built. That meant finding another way to make the new substance in sufficient quantities for chemical analysis.

The best he could do was arrange for batches of uranium nitrate to be bombarded with neutrons in a cyclotron for weeks and months on end. This gave him quantities of plutonium measuring no more than millionths of a gram to work with, so he gathered around him a small team of experts in ultramicrochemistry – the science of chemical investigation using minute quantities of substances.

By 14 August, Seaborg’s microchemists had succeeded in isolating a tiny quantity of plutonium.

This Napoleonic approach

The S-1 programme was investigating several different routes to an atomic bomb. In addition to the Met Lab project to construct a reactor and
produce plutonium, projects were also in hand to separate quantities of U-235 using gaseous diffusion techniques, electromagnetic methods based on an adaptation of Lawrence’s 37-inch cyclotron and centrifugal separation methods. The construction of a working reactor based on heavy water as a moderator was also being pursued in case the uranium–graphite pile failed for some reason. Construction of a heavy water plant was under way in Canada.

The MAUD Committee had strongly advocated collaboration with America in its July 1941 report, and yet the British were initially rather cagey in their approach to the Americans and somewhat preciously guarded what they believed was a lead in nuclear research. Cherwell had favoured continuing the project in Britain, or ‘at worst in Canada’. Chadwick was hesitant.

Several Tube Alloys physicists travelled to America during the first few months of 1942, including Peierls, Simon and Halban. They visited all the major centres of S-l activity, attended meetings of the S-l Committee and enjoyed a completely free exchange of information.

While the British team could consider itself ahead in terms of research on the theoretical principles of bomb design, it was clear that the Americans were moving ahead rapidly on all the experimental fronts. Work on the pilot gaseous diffusion plant at Rhydymwyn in Wales was continuing, but the British team could make no contribution to the experimental work on electromagnetic or centrifugal separation of U-235. These separation methods had not been fully explored in Britain and Tube Alloys did not have the capacity to undertake such work. And the MAUD Committee, having backed U-235, had not sponsored much work on plutonium.

The American effort was now very impressive. ‘One thing is clear,’ remarked Akers shortly after arriving in the US, ‘and that is that an enormous number of people are now on this work so that their resources for working out schemes quickly are vastly greater than ours.’ The American project had languished until the MAUD Committee report and Oliphant’s meddling had provided the impetus to establish the S-l programme. However, by the end of spring 1942 it was clear that the American project was overtaking Tube Alloys.

The letters exchanged at this time between Vannevar Bush and John Anderson were cordial but deliberately vague, and spoke of more meaningful collaboration when the projects were ready to progress from the pilot plant stage to full production. But the visits by Akers and the Tube Alloys physicists had convinced them of the importance of pushing for a full Anglo-American programme, managed by a joint council and supported by joint technical committees. Akers approached Chadwick, and Chadwick set aside his reservations. A proposal for full collaboration was put forward to Anderson’s policy council in June 1942.