The stereo camera John had bought during the war was stolen from his office at the University one winter and he started to look out for a replacement by the simple method of telling everyone he knew that he needed one. Before long a colleague had brought him a Manchester firm's advertisement for a second-hand 3-D camera, which John ordered forthwith. A letter came back saying that the camera was being withdrawn from sale because its shutter was not working. Having great faith in his ability to repair anything he replied that he would have it anyway, and so obtained it at a reduced price. He discovered that the roller blind that formed its shutter was only moving over part of its range and sometimes failing to shut at all. He cured the problem by winding it up and releasing it forty to fifty times, which probably cleared some dirt. Someone lent him a pulse length recorder and he checked the shutter speed but still found that the springs and gear wheels that were needed to operate it tended to stick, making a screwdriver to release them an essential accessory.Once he had the camera's mechanism working, he turned his attention to the lenses. They were set to focus from thirty feet to infinity, but John wanted to be able to photograph plants and insects in close-up. He made the front lens panel removable and put a spare pair of lenses into a second panel that could be slotted in place to enable the camera to focus down to six inches. Maybe you or I would not have a spare pair of lenses hanging around, but that was just the sort of thing John tended to accumulate! He performed a calibration by putting some graph paper up on a screen and focusing the camera onto the lines from a number of distances, and then fixed a roll-up steel tape to the camera so that he could measure distances of the objects he was taking accurately. The original camera used plates, but he cannibalised another old camera, putting the back of it onto his creation so that it could now take roll film. The body of the camera was made mainly of wood but after being dropped a couple of times it began to weaken a little at the joints, so John bought a sheet of titanium one millimetre thick and made a strong outer structure. (Steel would have been cheaper and easier to cut, bend and drill, but he liked the idea of titanium.) Later still he added a second-hand viewfinder and a brass shoe to take an electronic flash together with a suitable contact to link it to the shutter mechanism. Lastly he topped the whole thing off with a spirit level to help in taking pictures of scenery.
This camera had a tinny, goggle-eyed appearance by the time it was ready to take out on expeditions. It formed a good talking point, and John thoroughly enjoyed explaining its finer points to anyone who was overcome by curiosity on seeing him operating it. He always loved giving explanations. He regularly received letters from people outlining their inventions and ideas, including descriptions of perpetual motion machines and calculations disproving the theory of relativity. For each letter he would draft a careful reply to explain the underlying science. In the end, he got more than his fair share of these letters when he gained a reputation of being prepared to answer them and colleagues began to hand on their collections.
John's ability to explain things had also made him a popular lecturer among the University's physics students. He always managed to make his lectures interesting by adding his own outlook to the material but his greatest strength was his appreciation of his students' limits. He was quite clear that it was more important to promote a deep understanding of the basis of each part of the course than to pack every related fact into a one hour lecture: he would inform his students that a particular principle was perfectly easy and then proceed to lay it out before them in simple language, expecting only a minimum of previous knowledge, leaving his listeners impressed with their own abilities of comprehension. This way, everyone got to understand some physics, while the brighter students were expected to look the more advanced material up in books and papers. He chose to forget that, as an undergraduate, he had hardly ever bothered to check out the books and papers relating to lectures!
John was also becoming ever more in demand as a public speaker. As his earlier nervousness disappeared, he grew to enjoy these chances to air his views, and needed only the minimum of notes, often prepared on the back of an envelope during a train journey. For a number of years he did courses of lectures for the University extramural department, often on the subject of atomic energy. These courses were paid, but they were quite hard work because for each course a syllabus had to be prepared in advance, a reading list made out, and local publicity organised. Often left alone with the children for several evenings a week, Reinet began to wonder if John's popularity was altogether a good thing, and eventually protested that she did not feel that she and the family were seeing enough of him. He took this to heart but could not bring himself to refuse any invitations as he was flattered by the attention and didn't want to disappoint anyone. Instead, he felt guilty each time he entered another talk in his diary and put off telling Reinet until the very last moment, sometimes ringing her up with an embarrassed claim that he had forgotten to tell her about the meeting to which he was travelling at the moment.
The trip to China gave him an additional subject to add to his list of titles, but it also had an unfortunate consequence because he had joined the Britain China Friendship Association before going. The Labour Party, badly nervous of communist infiltration, had prepared a list of proscribed organisations, and the Britain China Friendship Association was on it. John would not be pushed to resign from an organisation he had chosen to join and so had to give up his Labour Party membership, but, unwilling to totally withdraw his support, he continued to pay the amount of his annual subscription in the form of a donation and also to vote for the party.
The Labour Party need not have feared that John was going to bring communism into their ranks for he had not been tempted to return to the Communist Party at any time during or after the war. But he did still believe in the ideals of communism and consequently admired Chairman Mao and the work he was doing in China and continued to admire Stalin uncritically even after his death in 1953. He did not believe that the British needed a person like one of these two to lead them, for he was convinced that Britain's democratic system was working perfectly well, but he felt that the uneducated peasants of China and Russia did not have the sophistication for such a system and needed the strength of a dictator to guide them towards a common good. Rumours of the unpleasant happenings in Stalinist Russia were of course making it to the British press but, as usual, exaggerated reports left John believing that there was no truth in them at all. It also became such a habit to defend both China and Russia against all slurs, that even when Khruschev denounced Stalin's crimes, John still tended to see Stalin as a victim, overtaxed by the impossible task of imposing collectivisation upon a populace that did not know what was good for it.
Heaver's death had come at a time when there were still heavy death duties on inherited capital. There were some shares from the Martin's fur company that had come to Heaver through his wife's family, and the dues payable on these somehow came out at far more than they were worth on the open market. John and Reinet started a certain amount of modernisation on the cottage they had inherited, with a view to using it for family holidays but unfortunately the valuation of the cottage itself for death duties was delayed until after the improvements were made, and also produced a punitive demand. They managed to pay the taxes and kept Heavers, but a couple of years later yet more funds were needed to buy a further lease on our Birmingham house. This was made the more costly by the requirement that the roof should be replaced and so, in the end, Heavers had to be sold.
However, after all the duties were paid and before the Birmingham lease needed renewing, there was still some money left over. It was decided that Reinet should make a trip to South Africa as she had not seen her parents for nearly twenty years. She took us away from school so that we could spend three months there getting to know our grandparents during the summer of 1953, but John could not desert his job for that long. He experienced a dreadful sense of loss when he said goodbye to his family, realising then what a large proportion of his life they formed. Left on his own in the house, he looked after himself perfectly adequately, although he did not particularly like it. He would take as many meals as possible at the University, but if he had to prepare food for himself at home, it would be extremely simple fare, often based on eggs. Moreover, he would keep one plate for the savoury course and one for the sweet, and never wash either of them up. He considered this a perfectly normal male approach. He backed this opinion up by describing what he had noticed about the various coffee groups in the Physics Department: the women liked to wash up their coffee cups immediately after each break whereas the men left them until they wanted their next drink or didn't bother at all. He thought the men's pattern to be superior for if one of them were to be killed on the cyclotron, he would have got away with a little less washing up!
On the family's return from South Africa, David started at senior school. He had won a place at King Edward's School, which had raised its standards above those of the rest of the Birmingham grammar schools and had a special entrance examination. This school was near the University, and now David and John started to walk down the hill together in the morning, a new opportunity to discuss physics, politics and world news. John always preferred to stick to facts in conversation, and although people and their strengths and weaknesses might be discussed in general, the emotional side of human nature was mainly left alone. To David, John had long been the moral centre of his universe, and he continued to assimilate John's views and make them his own. The Wye valley camping trip was followed a couple of years later with a walking tour in Cornwall, where much more respectable distances were covered, although this time they stayed in Bed and Breakfast accommodation.
Despite the fact that John was always busy, there were often opportunities to spend time with him. If he was going to the Physics Department on a Sunday morning through the demands of a current experiment, or simply to catch up on some work, he would take us with him to get us out from under Reinet's feet. There we would play in the lifts and run up and down the stairs of the Poynting building, never missing a chance to exclaim over the untidiness of Daddy's office. As the eldest, David was allowed to take some Geiger counter readings if there was an experiment running over the weekend.
There were also exciting romping games at home; John knew exactly how high he could throw a child without dropping him or her, somehow letting that child know that he was being careful about safety. Then there were wild chases through the house, which lent itself well to indoor games being large and having the wonderful advantage of a second set of stairs to the old servants' quarters. One such game, played when Celia's three children were staying, involved John, David and Nicholas having to get all four girls trapped in one room at once by catching and physically carrying them there! Less strenuous, but no quieter, an occasional evening would be spent with the whole family gathered round the piano to sing folk songs. These sing-songs started with Reinet picking out the melody on the piano, but after David had taught himself to play, he would thump out a rousing accompaniment. On holidays, the whole family would play board or card games in the evenings.
It was a general habit with John to use time constructively. He loved sitting and talking when he visited friends or relatives, but he also carried a small selection of tools with him, on the lookout for mending jobs he could do for them. On the rare occasions when he had nothing else to do, John would relax with some reading. When this was not something technical, it would be of a very light nature: science fiction and Agatha Christie detective stories were favourite forms of escapism.
When I was eight, John decided that I too should have a chance of a walking and camping tour. He equipped me with just such a lightweight pack as he had given David on his first trip and we set out from St Davids in Wales where the family was having a seaside holiday, to walk to Freshwater East where old friends were staying. (Brenda Swann and her family: before she had married, Brenda Ryerson had been Reinet's first assistant at the AScW) During this trip he gave me my first lesson on atomic theory as we walked, using his teaching skills to pitch his material at such a level that I could understand all that he said and yet find it exciting.
From that time on, I, like David, would expect any conversation with my father to have some intellectual content. I came to assume that interesting information would emerge from such contact and that I should take on the role of a pupil. Personal feelings did not come into the conversations, which were centred on facts although some of those facts would actually be John's own interpretations of the worlds of politics or science: once he had thought something through using his own logical mind, he was more than happy to explain his argument but then liked to have his conclusion accepted. For many years I was taken in by John's unemotional manner and therefore got quite a surprise when I eventually read the letters he had written to Reinet. Although he expressed happiness or satisfaction perfectly well, he had been brought up to put a brave mask over anxiety or unhappiness. I am sure he had his worries and difficulties but I believe that he really did think that most problems were soluble if dealt with rationally.
The environment of every child in a family is different, and somehow Jane and her father did not get into conversations of this type. Jane seemed from the first to have an innate lack of interest in scientific matters, which showed when John tried to talk with her and in turn reduced his interest in seeking her out for such conversations: he had become used to being flattered by David's and my interest. When her turn came for her first camping holiday, John took her on a canoeing trip along the River Avon from Stratford. Neither of them particularly enjoyed the holiday, but this was partly explained by the fact that Jane was found to have a temperature, due to flu, when she arrived home. Generally, Jane found the rest of the family's enthusiasm for scientific matters very dull for she had a simple preference for more active forms of entertainment. So she benefited as much as anyone from some additions to the garden. John and Reinet had agreed that a climbing frame would be nice for us, but when they looked at advertisements for them, those available were not only expensive but also not particularly interesting and so they decided to design their own. This was done in a democratic manner, involving the whole family - although Reinet held the pencil and vetoed impractical ideas. Once the design was finalised, John took it down to the University, and got one of the technicians to shape the pieces out of iron tubing. The pieces were assembled in the garden at number fifty-three, the whole painted and its legs driven eighteen inches into the lawn. A few years later, John located a heavy wooden table in the Physics Department that no-one seemed to want and he thought it might be useful. On a quiet Sunday afternoon, the whole family and one of David's friends shifted it the mile up the hill from the University with the aid of a couple of bicycles. It stayed in the garden for many years and served as a small ping-pong table although mastery of its rather unusual contours took some time.
John continued to find beach holidays rather tedious, although he was happy to accept that the children should have them. In 1956, shortly after Heavers had been sold, he rented it for a fortnight from the new owners, and the family had a country holiday there. John took Reinet and us children out on the old walks he had known from years ago, and, to give us an extra interest, got us to collect wild flowers and identify them from a book he had recently bought me as a birthday present. There was to be a small cash prize for every ten flowers correctly identified and a larger payment for any flowers declared rare by the book's system of stars, although there was of course an embargo on actually picking these.
The book was the 'Pocket Guide to Wild Flowers' by McClintock and Fitter, and during the holiday, John's own interest in wild flowers rocketed. He began to photograph them using his stereo-camera, and experienced a new thrill whenever he found one of the less common species. By the time he got home and had his films developed, a new and absorbing hobby had taken root: using the Pocket Guide as his bible, he started to make a collection of stereo-photographs of wild flowers always hoping to find a very rare 'three star' plant.
In 1953, Reinet started to look for work. Much as she had wanted more time with her family at the end of the war, she had now had eight years of being at home with very little intellectual stimulation and was frankly bored. After trying a couple of part-time jobs, she saw a post as a physics teacher advertised at Edgbaston High School, where Jane and I were in the junior school, and despite having no teacher's qualification, she was given the job. She found the first year extremely hard work, as she had to revise the physics in each part of the syllabus as she came to it and then shape it into a lesson. But she adored the work, never ceasing to feel excited as the proof of a principle emerged from one of her own careful explanations. Although the school hours allowed her quite a bit of time at home, she delegated as many household duties as she could. She paid for domestic help from the very beginning of her time at work and organised each member of the family to do a few regular tasks according to his or her abilities. When the ten-year-old David suggested that he would like his breakfast earlier in the mornings, she encouraged him to make it himself; this he did, cooking egg and chips for himself, his father and his sisters for the next eight years. (John avoided the chips.)
John was now throwing himself into using the cyclotron that he had helped to build. The first accelerators had produced beams of charged hydrogen, deuterium and helium only but there was now an interest in trying to get them to generate beams of heavier elements such as carbon, nitrogen and oxygen. The first such beams had already been produced but at low energies. Since the point of accelerating heavier particles in the cyclotron was to allow them to smash into other materials to initiate various new nuclear reactions, low energy beams were not going to be very useful; one of the ambitions driving this work was the hope that ions with larger numbers of protons and neutrons than deuterium could add more of them at once to the nuclei of existing atoms, in so-called pick-up reactions, creating new heavy elements which had never been seen previously.
To obtain a beam of heavy ions, John looked first at the possibility of accelerating carbon ions. However, the magnetic field used by the cyclotron to accelerate these was so close to that required to accelerate deuterons that it was difficult to separate them. He therefore decided to attempt to accelerate highly charged nitrogen ions, which were easily distinguishable from deuterons. There were two vital steps in the process he developed to achieve this. Firstly, he changed the internal pressure in the cyclotron to allow the presence of sufficient nitrogen in its more easily produced 2-charged (2+)-1- state that clashes occurred, which stripped off extra electrons from some of the ions (stripping reactions) to give 6-charged (6+)-2- ions. Secondly, it so happened that 2-charged and 6-charged ions could be accelerated by the same fields, and although the 2-charged ions moved at only one third of the velocity of the 6-charged ions, they could still both be gaining energy in the cyclotron at the same time and therefore interacting to produce further stripping reactions. The 6-charged ions were acted upon so effectively by the accelerating fields that much more energetic beams of nitrogen ions were produced than ever before.-3- A remaining difficulty of the two-stage acceleration of the 6-charged ions via the 2-charged state, was that the resulting beam contained both low energy 2-charged and high energy 6-charged ions, resulting in beams with a wide spread of energies.
With his high energy ion beams, John was now able to do some of the initial research into the main types of nuclear reactions induced by bombardment of various materials with heavy ions starting by aiming his nitrogen beam at aluminium foil. To interpret the results, chemical analyses of the resulting materials were needed and two radio chemists, Ken and Alma Chackett joined in the work. Speed was of the essence in the experiments that followed, and during each bombardment, John sat by the cyclotron target air lock until the bombardment was finished when he would whip the target holder out through the air lock, detach the aluminium foil target and tear along the underground passage from the cyclotron to the basement lab in the Poynting building. Once there he would drop the target into the acid solution that Dr Chackett had ready for him. The required chemical separation was then performed as fast as possible, so that John could then put the various products straight into the heavily shielded Geiger counters he had set up in the same lab to measure their radioactivity.
The chemical analysis of the products together with the measurements of their radioactivity defined not only the elements they had produced, but which isotope of each element was involved. The team was at first puzzled. One might have expected that adding a nitrogen nucleus to an aluminium nucleus, simple fusion of the nuclei would give the element resulting from adding 13 protons (aluminium) and 7 protons (nitrogen), which would be calcium with 20 protons in its nucleus. What they actually found was mostly phosphorus-32 with a little nitrogen-13, carbon-11 and fluorine-18. The table below will help to show how the numbers of protons and neutrons relate to each other in the relevant isotopes.
| Isotope | Number of protons | Number of neutrons |
| Aluminium-27 | 13 | 14 |
| Calcium-41 | 20 | 21 |
| Carbon-11 | 6 | 5 |
| Fluorine-18 | 9 | 9 |
| Nitrogen-13 | 7 | 6 |
| Nitrogen-14 | 7 | 7 |
| Phosphorus-32 | 15 | 17 |
In other words, to get phosphorus 32 after bombarding aluminium, only 2 protons and 3 neutrons could have been added to an aluminium nucleus.
After wondering for some time what might be going on, John suddenly realised that he could explain all the results with one theory. This was that the nitrogen nucleus could be viewed as a bunch of alpha particles.
| Number of protons | Number of neutrons | |
| Alpha particle | 2 | 2 |
Then the aluminium target would in effect be peppered with alpha particles plus a few spare protons and neutrons such that the phosphorus-32 was being formed from the aluminium by the addition of one alpha particle plus a stray neutron. Even the aluminium nucleus itself could be looked at the same way, as a group of alpha particles, and the fluorine-18 could be the result of a nitrogen nucleus picking up an alpha particle from the aluminium. The carbon-11 would then be two alpha particles from a nitrogen nucleus, minus an extra neutron. John called this his buckshot theory, which stated that atomic nuclei had a tendency to split into alpha particles.
The group then turned their attention to attempts to find new heavy elements. Uranium, with 92 protons, is the heaviest naturally occurring element, although short-lived atoms with up to 98 protons had been produced in other accelerators by this time. The Birmingham group hoped that by bombarding uranium with nitrogen ions they could produce element 99, the element with 99 protons. They got some results that looked as if they might have been successful, although later on John became convinced that they had only in fact got element 96 or 97, because of the usual breakdown of nitrogen into smaller alpha particles. However, at the time he mentioned his possible success to an American visitor, who immediately cabled to Berkeley to publish their identification of elements 96 to 102 at once; they had all been found among the debris of a test firing of an experimental atom bomb.
As children, we heard an awful lot about heavy ions at the dinner table, and although David probably understood some of it, Jane and I were bored rigid, always waiting for a gap in the conversations so that we could start up something more interesting such as a discussion of our favourite colours. For myself, I was never quite sure if he was talking about heavy irons; my lesson in atomic theory during the St Davids walking holiday had not got as far as ionisation! Others were of course more interested, and there were invitations to the USSR, the United States and later to Amsterdam, in each case to give the main lecture in a session devoted to heavy ion reactions and also to Stockholm to advise on certain problems in the building of a cyclotron.
When John made his initial application for a visa to the United States, he had to note that he had been to China recently. The response to this was an extensive form for completion; once again John was thoroughly annoyed not only by the implicit accusation that he was a communist when he was not, but also by the assumption that there was anything wrong with being one anyway. One of the questions asked him to list every organisation to which he had paid a subscription since 1920. John dug his heels in and decided that he would do just that, going to a great deal of trouble to identify all such organisations, however small an amount of money he had contributed to them. He added a note to the effect that he could never have known, let alone remembered, all the charities to which money was given from the church collections he would have supported every Sunday while a child. This form did not produce a visa so John did not get to the conference; however, it did not produce a refusal either and for the rest of his life, John liked to say that he was still awaiting a reply!
The invitation to go to Russia to join a conference of the USSR Academy of Sciences came in 1957. Since his previous visit to Russia on the way to China, John had attended evening classes in Russian in order to be able to understand the Russian papers that were now being published on heavy ion reactions. I remember his giving me a short Russian lesson every morning at breakfast time for a few months, which would have been good revision for him, but this may well have been a year or two later. Asking the way to places did turn out to be easier than on his previous visit, but as is usual when one knows only a little of a language, interpreting the answers was not. However, the physicists he met were delighted with his efforts, although usually they spoke English with him, their English being better than his Russian.
Georgy Flerov, the senior worker on heavy ions in Russia, took John under his wing, and, horrified by his walking the hundred yards or so between the conference buildings with nothing on his head, obtained a beautiful fur hat for him, which John found very comforting. On about the third day, after John had given his paper, the visitors were all invited to go round the Moscow Atomic Energy Institute. Flerov warned John that the party would be taken round by an Intourist guide who would be able to do no more than take them to each of a number of windowless brick buildings and read out a lengthy but superficial explanation of what went on inside. So he suggested that John should go through the guard room with the others, but when the party reached the first building, he should fall behind and go round the building on the right, where he would find another physicist who would bring him through to Flerov in the cyclotron lab. So John did just that, and spent a memorable morning sitting on the cyclotron magnet, drinking coffee and chatting to the two physicists about technical problems. Flerov had read John's paper on two-stage acceleration and not only shared his regret at the resulting energy spread of the accelerated particles, but explained how he had by-passed that by developing a very high power ion source. He then presented John with blueprints, showing the detailed structure of the source. Some time after this transaction had taken place, they heard a voice speaking English and withdrew from the cyclotron for five minutes, while a guide, still full of enthusiasm, led a jaded group of visitors through the area.
John made the most of the rest of his stay, attending the conference lectures only if he thought they might be interesting. He did a little sight-seeing, and managed to visit the University Physics Department where he was taken to see a fourth year practical class. He took the chance to discuss ideology with some of the students and asked them whether they found the compulsory lectures on Marxism and communist theory useful to their physics. There was a bit of a pause while they looked at each other, and then one of them summoned up his courage and said: "Well, we find it a very useful time to write up our laboratory results."
On his return to Birmingham, John's first thought was to build his own ion source to Flerov's specifications. But this would need money, as the source needed very high power and also one source could last only about twenty-four hours, after which its twenty grams of tungsten would need replacing. So he went to Professor Moon to ask if he could make an application to the Science Research Council for a grant to support the work. To John's dismay, the Professor flatly refused him permission to make such an application on the grounds that it was bound not to be successful and that he wanted the cyclotron to be put on to other work anyway.
This was one of the most depressing things that had happened to John in his working life so far. He knew he was doing good work, but there seemed no obvious way to circumnavigate this restriction on its future development.