Fuchs sent a toy from Mexico to his six-year-old nephew in Cambridge, Stephen Heineman. He bought a piece of silver jewellery for Suzanne Deutsch, who had given him her home-baked cookies, and when he got back to Los Alamos he presented it to her with a courtly little poem addressing her as a ‘spoiler of men*. This was a farewell present before Martin and Suzanne Deutsch left; he was to take up a post at MIT. Fuchs also bought a Navajo bracelet with a large turquoise stone for Genia Peierls, and presented it to her before the Peierls left for England.
For those who remained at Los Alamos after the war there was more work to be done on atomic weapons, on making them more efficient and producing them more economically. Then preparations began for the first postwar atomic bomb test, scheduled for late 1946 at Bikini Atoll. As a Briton, Fuchs was given no part to play in these. However, when a physicist who was doing experiments for the test, Louis Slotin, was killed by a burst of radiation in a laboratory accident, Fuchs was assigned the task of working out exactly what had happened and how. There were to be echoes of this later on in his career, back in Britain, when he worked on radiation dangers.
Another big step in destructive power was now on the horizon, as great in its magnification as the jump from high explosives to the atomic bomb. This was the hydrogen bomb, called by the scientists simply the ‘super’, the prospect that had captivated Edward Teller. It was a bomb that would release energy by nuclear fusion, and would employ a fission bomb as a trigger. No one outside the small world of atomic physics knew about this possibility, nor could most people imagine it, reeling still from the shock of the power of the atomic bomb. It might not work, but it was a fascinating idea and now it was discussed purposefully at Los Alamos. Teller gave several talks on the subject.
Fuchs contributed a suggestion of a way to ignite a fusion explosion using the implosion technique. It turned out not to have any relevance to the way that a hydrogen bomb was actually built, but not much else that was said at this time had either. Fuchs took part in all the discussions and, by the time he left Los Alamos, he knew as much as anyone else there about the ‘super’. But no one’s knowledge had advanced far beyond the original concept, and no one knew how to make a hydrogen bomb work, or even for certain whether it could be done.
Meanwhile, an event took place in Ottawa, unreported at first, that set off a chain of other events that was to touch the feelings of all the scientists involved in the atomic bomb programme, and of Fuchs in particular. On 5 September 1945, three weeks after the end of the war, a twenty-six-year-old cipher clerk at the Soviet Embassy, Igor Gouzenko, walked out of his office carrying a file of 100 documents that he had stolen from a safe. These contained details of a spy network run from the Soviet Embassy. His intention was to alert the Canadian authorities, and then make a new home in Canada for himself and his wife and their baby son.
He took the documents to a newspaper and to the Prime Minister’s office, and was turned away from both places. The newspaper reporter gave no credibility to this foreigner with a strange story; the Prime Minister’s office refused to have any dealings with a junior clerk at the embassy of a friendly power outside normal diplomatic channels. Only when he sought refuge in a neighbour’s apartment from pursuers from his embassy, and the neighbour called the police, did his story and his stolen documents come to the attention of the authorities.
Most of us have grown up in a world in which the Western powers and the Soviet Union are adversaries, in which espionage is a normal weapon in this adversarial contest, and both sides try to suborn the nationals of the other. But in 1945, in the immediate aftermath of the victory that Russia and the Western powers had won together, such ideas were remote from the minds of the public, and played a very small part in the thinking even of Western governments. Even when the Gouzenko documents were analysed and the existence of the spy ring was revealed, the Canadian Government hesitated to act for fear of damaging the prospects of co-operation between the Soviet Union and the Western powers in the postwar world.
The documents revealed that several Canadians and one Englishman were spying for Russia. The Englishman was Alan Nunn May, a bachelor with a rather colourless but pleasant enough personality, an extremely able physicist, who worked in the Montreal laboratory of the atom bomb project. His induction into espionage two years earlier came about because the Soviet intelligence service knew by then that a major programme to build an atomic bomb was under way.
Soviet intelligence sent a message to their station in Ottawa, and presumably to other stations as well, with instructions to try to get any information they could on this programme. Nunn May had been spotted as a potential recruit already, before he went to Canada, because of his known pro-Soviet sympathies. He was approached in Canada by a Soviet agent, and agreed to help. All this was disclosed in the papers that Gouzenko gave the authorities.
Nunn May was able to give the Russians details of the work in the Montreal laboratory. He also stole from the laboratory minute samples of uranium 235 and another fissionable isotope that is created artificially, uranium 233. These were so important that a colonel on the staff of the military attaché at the Soviet Embassy flew with them to Moscow.
Nunn May returned to England soon after the end of the war and took a teaching post at King’s College, London University. Arrangements were made for him to contact a Soviet agent in London. Special Branch police officers from Scotland Yard kept him under surveillance. Gouzenko’s defection and the discovery of the papers were still secret. Then, on 15 February, the Canadian Prime Minister, Mackenzie King, announced that evidence of a spy ring had been uncovered, Canadian police made thirteen arrests, and Special Branch officers called on Nunn May. He confessed five days later.
The discovery of the spy ring was a shock to the Western public, and Nunn May’s arrest was a shock to the atomic scientists in particular. The day after it was announced several people were discussing it at Los Alamos, including Fuchs, Egon Bretscher and his wife Hannah, and Else Placzek. She was the wife of the Czech-born scientist Ernest Placzek, but she had previously been married to a physicist working in the Montreal laboratory. She had known Nunn May in Montreal, so the others all asked her what he was like.
She found it difficult to ascribe any special characteristics to him. She said he was very quiet and one did not notice him much, and then she said, ‘He was just a nice, quiet bachelor, very helpful at parties. Just like Klaus here.’ Fuchs flushed and became visibly uncomfortable. The others assumed this was just because attention was drawn to him.
One of the people questioned in the follow-up to the Gouzenko disclosures was Israel Halperin, Professor of Mathematics at Queen’s University, Windsor, Ontario, and a member of the Canadian Communist Party. His papers were searched and Fuchs’s name was found. This was only because Halperin had been given Fuchs’s name by a friend of Kristel Heineman’s when Fuchs was in the internment camp in Canada, and he sent Fuchs some magazines while he was in the camp. The two had never met. None the less, this information was passed on to the British security authorities, along with many other minor details arising out of the investigations, but not until 1949. (Halperin was charged with espionage but acquitted.)
Nunn May’s trial in Britain and the reaction to it provide some insights into the political atmosphere of the time, as well as bearing on Fuchs’s own actions. The Attorney General, Sir Hartley Shawcross, prosecuted. Nunn May pleaded guilty to the offence, but his defence counsel, Gerald Gardiner, KC, made a strong speech in mitigation. He pointed out that the charge referred to communicating information ‘which was calculated to be or might be useful to an enemy’. But, he said, when the information was passed over, the Soviet Union was a valued ally; Soviet forces were advancing on Berlin, while British troops had not yet reached the Rhine.