Most of the attendees at the inaugural sitting of this hand-picked panel lent it the air of a Cavendish Laboratory reunion. There was Cockcroft, Philip Moon and committee chair George Thomson, a Nobel Prize winning physicist and son of Rutherford’s predecessor J.J. Thomson. The fourth figure, a guest dressed immaculately in a tailored dark suit who stared intently from behind heavy-rimmed glasses, was introduced as Lieutenant Jacques Allier, a Parisian banking executive recently returned from a high-stakes French intelligence mission in Norway.
Oliphant had spent much of that morning’s train journey from Birmingham reading the latest news reports from Scandinavia. There were pages dedicated to the previous day’s dire development, Germany’s invasion of Denmark and Norway, which had shattered vain hopes that the Phoney War might yet yield a fragile peace. With that fantasy dashed, the threat to Britain was heightened. But Oliphant’s more immediate concern lay with the welfare of his friend Niels Bohr – whose mother’s Jewish family was prominent in Danish banking and political circles – now trapped in occupied Copenhagen.
The object of Allier’s daring assignment into dangerous territory had already been explained to Oliphant. The Frenchman had been sent to secure all known stockpiles – 185 kilograms, successfully spirited to Paris via Amsterdam, Edinburgh and London – of heavy water: the source of the deuterons so coveted in Oliphant’s earlier disintegration experiments, and a known moderating agent for nuclear fission.
It had been established that slowing neutrons in a fission reaction prolonged the time they spent in proximity to nuclei, thereby increasing the chances of ‘capture’ and the resulting atomic split. Research conducted in the United States would later establish that pure graphite served that purpose more effectively than heavy water. Yet the interest that Hitler’s Germany had shown in the world’s only plant producing heavy water in industrial quantity – the Norsk Hydro-Elektrisk electrochemical facility near Rjukan, in mountainous terrain west of Oslo – indicated that the Nazis were indeed on the uranium trail. This revelation was made more troubling with the overnight news that Norway was now under German control.
Allier had arrived in London a day earlier from Paris, where Frédéric Joliot-Curie had recently made significant progress in fission experiments using heavy water. Joliot-Curie had published a paper containing further details about the prospects of a self-perpetuating chain reaction in uranium. As a result, Oliphant’s former Cavendish research partner Paul Harteck – who had returned to his native Germany soon after the pair’s tritium discovery using heavy water in 1934 – had written urgently to the German War Office.
Harteck drew attention to ‘the newest development in nuclear physics which . . . will probably make it possible to produce an explosive many orders of magnitude more powerful than the conventional ones . . . That country which first makes use of it has an unsurpassable advantage over the others’.2
Allier was only present for the first part of that initial London meeting. He informed the ashen-faced group about France’s concerns regarding the measures Germany was taking to obtain information about Joliot-Curie’s work, as well as their hopes to corner the world’s supply of heavy water. Then, having urged that no details of his statement be shared beyond the walls of Burlington House, he was taken to see Tizard. He provided him with a list of all known German scientists likely to be involved in any nuclear research program.
The committee’s next meeting would be held a fortnight hence, by which time James Chadwick would join its membership. Before long, a technical sub-committee would also be commissioned to examine practical rather than policy matters, and the main committee would grow to include Patrick Blackett.
Tizard believed it best not to pre-empt the committee’s findings, yet he remained unconvinced as to the imminent prospect of a uranium bomb. After only two meetings of the ‘Thomson Committee’ (as the group had become unofficially known), Tizard outlined his thoughts in a letter to the War Cabinet Secretariat’s assistant secretary, Wing Commander William Elliott.
‘I adhere to the view that uranium disintegration is not in the least likely to be of military importance in this war. On the other hand certain physicists say that the controlled disintegration is a scientific possibility, and the French are excited about it – I think unnecessarily.’3
The impetus for discerning whether or not a bomb could be successfully translated from a five-page memo to a massive manufacturing facility was therefore driven largely by the men of science – of which Mark Oliphant was among the most active.
This was certainly not because they were hellbent on producing the ultimate weapon. Nevertheless, the information coming from intelligence operatives such as Allier pointed unmistakably to Germany’s atomic ambitions. Given Hitler’s disregard for life when pursuing his ideological obsessions, the fear that he might achieve atomic weapons capability was exacerbated by the terrifying likelihood that he would then unleash those weapons on targets that brought maximum devastation. Beating Germany to completion of the bomb seemed the only viable means of avoiding that doomsday scenario.
Naïvely, many of the scientists believed that if the theory were proven, there would be no need to deploy the bomb in combat. They imagined that a mere demonstration of its breathtaking power would end the contemporary conflict, and likely quell any sane leader’s appetite to pursue war in the future.
However, the main rationale that drove Oliphant and his ilk at that time was ingrained professional curiosity. A complex question of scientific inquiry had been posed, and their trained instinct was to work tirelessly until it was answered.
* * *
So significant was the volume of research that would be needed in such urgent circumstances that the laboratory work was split among four of England’s foremost universities. At Cambridge, the properties of the recently discovered element plutonium would be examined to gauge its potential as a bomb source, along with experiments on the role played by heavy water. Under Chadwick’s direction at Liverpool, testing was undertaken to ascertain whether the thermal diffusion method that had been initially employed by Frisch (using the Clusius apparatus) offered the most efficient method for separating the required quantities of the uranium-235 isotope. Researchers at Oxford University were also assigned that task.
The experimental data being collected and submitted by these laboratories was sent to Birmingham, where it was studied by Peierls. Oliphant’s Birmingham facilities would also be engaged in exploring the optimum method of separating uranium-235 isotopes, but to do so he needed to identify a researcher capable of quickly coming to grips with the subject matter.
Of course, the ideal candidate already existed among his laboratory staff. However, Otto Frisch remained an enemy alien and was therefore disqualified from joining the committee, or even being briefed on its discussions. Frisch would eventually receive clearance to continue his separation experiments, but Oliphant was pointedly instructed to impress upon him the iron-clad confidentiality of his work.
To help progress the cause, Oliphant also set about converting the magnet of his cyclotron, still unfinished due to the priority placed on ongoing radar research, for use as an isotope separation system. As he had explained to colleagues at Birmingham during a lunchtime lecture, the battle against Nazi Germany loomed as ‘a physicists’ war’.
But sourcing further stocks of uranium so Frisch could carry out his investigations would prove a challenge, even for someone with Oliphant’s talent for persuasion and, where necessary, coercion. He secured from British manufacturing giant Imperial Chemical Industries a few grams of uranium hexafluoride, a white solid that sublimes at moderate heat to form a highly toxic gas, and that was reviled in laboratories because it corroded virtually every surface it touched.
With uranium supplies so strictly controlled and the opportunities to separate meaningful volumes of the 235 isotope just as scarce, Frisch was compelled to search for alternative methods of ascertaining vital information on uranium’s atomic cross-sections
.
In keeping with Bohr’s theory, he surmised that if natural uranium was bombarded with slow neutrons then fission would not occur in the prevalent 238 isotope. Consequently, any observable reaction must be occurring within the rare uranium 235. The difficulty with pursuing that mode of attack was that radon gas – acknowledged as the premium source of the neutrons that were then fired at the target as gamma radiation – was as difficult to procure in wartime Britain as was uranium. Unless, Frisch suspected, one set Oliphant on the trail with his gift for problem-solving.
Oliphant knew that Manchester Hospital maintained a supply of radon gas for its nuclear medicine needs and that radon, despite its half-life of just a few days, invariably replenished itself from a base supply of radium. Due to the imminent threat of air attack, however, the hospital had evacuated its radium stocks – of which there was barely 100 grams across the whole of Britain – for safekeeping to the Blue John Cavern. This was a network of subterranean shafts and passageways among the barren moors and glowering uplands of Derbyshire’s windswept Peak District. The fluorescent blue stone that gave the landmark its name had been mined in the area for centuries.
Oliphant negotiated with Manchester Hospital for his Austrian researcher to gain access to the remote cave site, set more than three kilometres from the nearest village. The venture required Frisch to travel by train to Manchester, where he was met by a driver who took him the remaining forty kilometres over the gritstone plateaus and peat-rich earth of Dark Peak. His mission was to collect a ‘seed’ – a delicate, sealed ampule – of the known carcinogen, then transport it by the same means back to Birmingham.
Armed only with a briefcase and mild anxiety, Frisch arrived at the entrance to the Blue John’s wet and gloomy subterranean chambers, which were cut into the coal-black rock and surrounded by heather-fringed grasslands.
Down I went over slippery ladders and through narrow, muddy passages to a slightly larger cavity where, incongruously, there was a laboratory table with a lot of glassware on it, bulbs and stubs and stopcocks, rather like the equipment I had used in Hamburg. That was the plant for ‘milking’ the radium, for extracting the radon and compressing it into a small glass capillary, no longer than half an inch.
At Oliphant’s request the radium had not been milked for a whole week so that a large amount of radon had accumulated. Less than an hour later, when the local technician had done the work for me, I walked out with my little suitcase containing a heavy block of lead at the centre of which was this tiny capsule full of radon, equivalent in radiation to about three-quarters of a gram of radium.
Any safety officer would shudder at the thought that I walked out with that thing, protected by only a couple of inches of lead, and that I travelled within a few inches of that radiation source first by car and then by train. Today that would be considered an unacceptable radiation hazard both to myself and to other people in the compartment.4
One danger Frisch was unlikely to encounter on his day-long trip, which then led to thirty-six hours of uninterrupted experiments at the Birmingham laboratory, was having the true nature of his mission exposed. He had taken to heart Oliphant’s security edict, and any information that flowed between members of the Thomson Committee and others on the periphery, including Frisch and Peierls, was deemed so sensitive that labelling such communiqués ‘Top Secret’ would only heighten suspicion. Instead, Peierls obtained a rubber stamp cut with a single star, which he would impress upon every confidential document ferried between the committee and the ‘aliens’. Those he considered to be ‘Top, Top Secret’ received two stars.
* * *
It wasn’t only the committee’s correspondence that required rigorous security measures. The group’s name also needed to be changed, given that Thomson’s involvement surely identified it as pertaining to fission, since he had specialised in physics at London’s Imperial College before the war.
By August 1940, it had adopted the title ‘MAUD Committee’, which some maintained was an acronym for Ministry of Aircraft (Production) Uranium Development Committee. Or possibly Military Application of Uranium Detonation. However, given the lengths taken to obscure the committee’s purpose, these would have represented clumsily obvious codenames.
The alternative explanation is much more quixotic, and preferred by a number of the committee’s members in their post-war memoirs.
It harked back to a cryptic telegram sent by Frisch’s aunt, Lise Meitner, to the head of the physics department at London’s King’s College during the aftermath of Germany’s occupation of Denmark. This was a time when concern ran high in the global science community as to Niels Bohr’s whereabouts and safety. In the hope that her update on Bohr’s welfare might be disseminated to his many friends and former colleagues in Britain, Meitner cabled in economic shorthand ‘Met Niels and Margarethe [Bohr’s wife] recently but unhappy about recent events. Please inform Cockcroft and Maud Ray Kent. Meitner.’5
While confirmation that Bohr and his wife were safe – though unable to communicate directly – was gratefully received, the reference to ‘Maud Ray Kent’ was inexplicable. It therefore set minds racing as to the encrypted message the Dane was seemingly trying to send.
Cockcroft felt it referred to the unpalatable reality that the Nazis had successfully developed some sort of death ray. Intelligence officers called in to try to decipher the oblique meaning thought it was more likely a warning about Germany’s progress in the race for an atomic bomb. By replacing the ‘y’ in ‘Maud Ray Kent’ with ‘i’, it became an anagram of ‘radium taken’.
Concern grew to the point where Ralph Fowler, Rutherford’s sonin-law, wrote to Tizard pointing out that while some of the theories floated were fanciful, the premise underpinning them was ‘sufficiently reasonable to make one worry’.6 Ever the pragmatist, Oliphant ventured that the whole matter could be readily resolved by having the British Embassy in Stockholm, the city where Meitner continued to live in exile, contact her directly for clarification.
That route was not pursued, however, and it was not until three years after the MAUD Committee earned its title that Bohr was finally smuggled out of Denmark and the truth was revealed. This happened when Bohr inquired as to whether his original message had been passed on, as requested, to his family’s much-loved governess during their earlier residence in Britain – Miss Maud Ray, who had since relocated to the south-east county of Kent. Her exact address, rather like the meaning that gave rise to myriad conspiracy theories, had been lost in transmission.
* * *
The MAUD Committee’s heaviest workload coincided with the Germans’ most sustained bombing attacks. From the late summer of 1940 through to the final weeks of spring the following year, around 30,000 tons of explosives were dropped on British targets stretching from Cardiff in South Wales to Scotland’s western port of Glasgow. The number of dead topped 40,000, many of them civilians. Hitler’s plan to pummel Britain into surrender meant residential tenements became as vulnerable as munitions factories.
The village of Barnt Green – where Peto’s red-brick walls now echoed with emptiness and remained bitterly cold due to the shortage of available coal – might have been spared the nightly threat of Luftwaffe bombers. Birmingham, however, remained a round-the-clock war zone. The network of industrial-era transportation canals radiating from the city’s centre provided a handy navigational aid for Luftwaffe pilots, and fires blazed across the city on a nightly basis.
Amid the howl of incoming explosives and bursts of shrapnel from anti-aircraft shells, the distinctive purple livery of vans belonging to the Cadbury family’s eponymous chocolate company, founded in Birmingham, became a regular sight. They would arrive at buildings where firefighters battled flames, and young women wearing steel helmets would alight to administer fortifying mugs of steaming cocoa.
As the Nazi air offensive worsened, the university came under direct threat. In mid-1940, in the first weeks of the Battle of Britain, an incendiary bomb exploded within a
metre of the front gates. When another penetrated the supposedly fireproof roof of Oliphant’s prized Nuffield Laboratory and set the rafters ablaze, the campus fire brigade tore out the ceiling and extinguished the flames while ensuring that valuable cyclotron equipment within was spared from water damage.
Staff were assigned to teams that took turns in maintaining nighttime vigils. Between bouts of fitful rest on a makeshift bed in the laboratory, Oliphant would keep watch through the porthole windows of the Poynting Building’s bulwark façade. From there, he would observe the orange light through the billowing smoke that cast an apocalyptic glow upon the horizon.
One night, the air-raid sirens alerted me. Half asleep I pulled on a dressing gown and made for the door to see what was happening. I walked straight into the glass door of the library. This shattered with a tremendous noise, cutting my eyebrow so that blood poured down my face. Putting my hands up, I thought ‘that bomb got me! I’m finished!’ Then I was somewhat disappointed to find that I had survived.7
Later in the war, Oliphant arrived at work one morning to find that a 500-pound (225-kilogram) bomb had slammed through the Poynting Building’s roof and into his first-floor office, where it lay unexploded behind a bookcase. The delicate defusing required army experts, who forbade the professor from entering the room, either to watch them operate or to access his files. ‘I was annoyed, for I wanted urgently some correspondence there about a visit to America, but they were adamant.’8
At the height of the Blitz, Oliphant travelled to London at least once a month when the MAUD men convened at Burlington House. The timing of the committee’s sixth meeting in mid-September 1940 was especially traumatic, as London had sustained relentless bombing raids every night for two weeks. After months of targeting RAF airfields and radar installations, Hitler had decided that London would wear the assault designed to bring Britain to its knees.
The Basis of Everything Page 29