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It used to be a cliché that one always remembered where one was when the news came through that President Kennedy had been assassinated. I remember exactly where I was…
It was a Friday evening, and the band were playing at the British Legion Club in Oldfield Lane in Greenford. Our drummer, Clive, was late arriving, the reason being that the news was just breaking on the radio as he was about to leave the house. It was a considerable shock. With hindsight, I came to realize that Kennedy nearly started the Third World War over the Cuba Missile Crisis and he certainly presided over the start of the Vietnam War. But with all that he was a radical, socially conscious and charismatic leader, and was responsible for mankind getting to the moon. Ironically, both Aldous Huxley and C. S. Lewis died on the same day; had it not been for the incident in Dallas, surely either of those events would have been headline news. Like the Woody Allen character in Annie Hall, I too became fascinated with the various conspiracy theories surrounding Kennedy’s killing. But the latest high-tech analysis of the evidence suggests that, the grassy knoll notwithstanding, there was after all, just one gunman, and he was positioned in the Texas school-book depository. But the 22 November has further resonances for me… In 1990 on the 22nd November I was sitting in a ponderous budget meeting at EEV, when the MD’s secretary came in with the news that Margaret Thatcher had just resigned. ‘Ah, there is a God!” I exclaimed, and received a poisonous look from the MD for my trouble.
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Have you ever wondered why ‘clockwise’ is the way it is? The answer is very simple: sundials.
The first mechanical clocks had no dials, they simply sounded bells at the hour, half-hour and quarter. When clocks were fitted with dials and hands, naturally they copied the sundial. On a sundial, the shadow of the gnomon, which points to the time, moves clockwise through the day; the first mechanical clocks simply replicated this. Of course sundials only work like this in the northern hemisphere; south of the equator, the shadow on a sundial moves anticlockwise… Proof, if it were needed, that clocks were not invented in Australia. Further to the previous post, my PhD project at Essex University in 1971 was to build a TEA laser, to be used not with CO2 but water vapour. An American group had discovered a laser line in water vapour at 28 microns, and it was decided that this would be a useful wavelength with which to extend the work at Essex University on the photon drag effect.
Photon drag detectors were incredibly simple; take a crystal of germanium, solder some electrodes to it, shine a powerful infrared laser beam at it, and a voltage would be generated proportional to the power of the laser beam. The initial work had all been done at Essex in CO2 at 10.6 microns and the department wished to probe the effect at different wavelengths. The laser I built worked fine with CO2, but that was no surprise; with water vapour I got nowhere. For weeks and weeks I persevered but could extract no laser output. I shared an office with an Egyptian student, Salah, a lovely gentle man, who was working on a five micron laser. We were chewing the fat one day, when he mused that hydrogen and oxygen combine to make water… The reaction is exothermic – releases energy – and this could help achieve a population inversion, a requirement for laser action. It all seemed to make sense, although hydrogen and oxygen notoriously combine explosively. I decided that it would be safe at low pressure, and I fixed up a hydrogen and oxygen supply to the laser along with some helium. Gingerly, I ran up the high voltage. I got a beautiful blue – violet discharge but no laser activity. I tried increasing the pressure; nothing; I increased the pressure again; still nothing. Slowly I increased the pressure some more and there was an almighty bang. The laser tube exploded, throwing the end with a mirror assembly thirty feet down the laboratory where it shattered against the end wall. I hit the ground and crawled towards the power supply where I managed to shut off the power by the expedient of pulling the mains plug out of the socket. It was all very quiet except for the ringing in my ears… That was the end of my water vapour laser. My supervisor was sympathetic, and somehow cobbled together an alternative project to allow me to continue with the degree work. I was able to salvage much of the hardware and repaired the ‘water vapour’ laser, using it with CO2. It did finally take six years before I was awarded the degree. When I joined the now defunct Department of Physics at Essex University in 1971, my first task was to build a CO2 ‘TEA’ laser. My knowledge of mechanical and electrical engineering was practically zero, and it is a constant source of wonder to me that I never managed to kill myself with the 30 kV power supply.
In 1974, my SRC studentship at an end but my PhD work quite unfinished, I was taken on to the staff as a ‘Post’ Doc, and given a project to build a high stability TEA laser for use in Edinburgh at Heriot Watt University. The application was to optically pump a spin-flip (tuneable) Raman laser. A source of tuneable laser radiation was the Holy Grail of the laser community at the time. The objective was to build a laser capable of sustained operation at 100 pulses per second – the standard at the time was about one pulse per second – with unprecedented spatial and temporal uniformity. I am pleased to say that all of the initial design criteria were achieved, although the resulting system was a quite impractical monster, due mainly to a lack of engineering supervision and peer review. However, it did all work, and my very first solo effort in writing a scientific paper described the results. I have just put a copy of the original on the publication page for download. Reading it through, I am taken right back to the period more than forty years ago when the work was done. It was, in a sense, like Brunel’s Great Eastern steamship. A great behemoth, built for a particular purpose – one for which it was never used – totally impractical and very expensive to build. But it did work! I’m guessing that few if any CO2 TEA systems as good have ever been subsequently constructed, mainly because there just is no need for them. It was a great learning experience though, and the paper describing it stands as a record of what was achieved. If there is anyone out there planning to build a high-stability CO2 TEA laser, I am available for consultancy…  The photograph was taken in Ealing in 1951-2 – latest, summer ’52. It shows me, on the right, on the day of my first Holy Communion. My father, probably, took the photograph. I do not have a picture of my last Communion, but it took place sometime in 1961…
The lad on the left is Jackie Arkeltoski – as I remember it, possibly Arketowski. He was my best friend, along with Kevin Messant – not in the picture. All I remember of Kevin, is that he went to Devon. We were three of five boys in a class of 25 girls in the second primary year at Lourdes Mount Convent School in Ealing. Of the girl in the middle I have virtually no memory. She might have been Irish, and her name might have been Theresa but there my memory fails me. I wonder what they are all doing now? |
AuthorWelcome to the Mirli Books blog written by Peter Maggs Archives
December 2024
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