That third pion
In his recent book Facts and Mysteries in Elementary Particle Physics (CERN Courier October 2003 p52) Tini Veltman states that some people believe Marietta Blau should have shared the 1950 Nobel prize with Cecil Powell for the development of the nuclear emulsion technique. He also credits me, much too generously, with the discovery of the pion. Since the discovery of the pion and of strange particles in 1947 really kick-started the 50 year history of high-energy physics at accelerators, perhaps I may pass a few comments as one of the last survivors of that era.
The development of the nuclear emulsion method for recording high-energy charged particles involved several physicists worldwide during the 1930s. The work of the Viennese ladies Marietta Blau and Hertha Wambacher (an unlikely pair - one a Jewess and the other an active Nazi party member) is well known. They exposed Agfa emulsions sensitized with pinakryptol yellow on the Zugspitze and Hafelekar and recorded a few nuclear disintegrations. Comparable contributions were made at that time by Zhdanov in Russia, Powell in England, and Wilkins, Rumbaugh and Locher in the US. However, the real breakthrough was made in 1946, when at the behest of a panel set up by Blackett and chaired by Rotblat, an industrial chemist, C Waller of Ilford Ltd in Essex, produced the first "concentrated" emulsions, with four times the normal halide/gelatine ratio, sensitive enough to make the tracks of mesons visible for the first time.
With regard to the discovery of the pion, it is true that when at Imperial College I published the first example of nuclear capture of a negative pion in January 1947. Occhialini and Powell at Bristol published six more examples two weeks later. The first two examples of decay at rest of a positive pion to a muon (and neutrino) were published by Lattes, Occhialini, Muirhead and Powell in May 1947. In the following July, I observed a third example, but although it appeared in my thesis, I never published it. Valerie Gibson of Cambridge once asked me: "Why not?" My reply was that the two Bristol events gave the same range for the muon, convincing me that it was a simple two-body decay. Confirmation from a third event was not really necessary and I didn't want to clog the literature! However, confirmation for the world at large really had to wait until October 1947, when the Bristol group published 10 more complete pi-mu decays from emulsions exposed on Mount Chacaltaya.
Tini Veltman has kind words for Giuseppe (Beppo) Occhialini, who indeed missed out on sharing a Nobel prize with either Blackett or Powell. Occhialini spent the Second World War in Brazil, and became a mountain guide. I am told that even now if you get lost in the Andes and shout "Beppo" loudly enough, people will come to your rescue. He is also famous through the BeppoSax satellite named after him, which made a major breakthrough in pinning down the origin of gamma-ray bursts. So Occhialini's name lives on.
Don Perkins, Oxford.
Why Weep for ISABELLE?
I would like to thank the CERN Courier and Gordon Fraser for putting out a fair review of my rather unusual book Weep for ISABELLE. (CERN Courier November 2003 p48). Just seeing the review in print gave me delight, and I really have no bones to pick with it. On the other hand, Gordon chose to take a stab at the question of what drove me to write the book. This is precisely the territory, that of what makes people do what they do, that I explore in great depth in my 600-page tome. It is a tough place to manoeuvre in, filled with dark alleys, dead-ends and unseen obstacles. Gordon concludes that I was embittered by a perceived injustice done to me, the obvious implication being that I wrote the book to try to get back at those who hurt me. It was a catharsis, he says, presumably to purge me of the demons of the night.
Actually, his interpretation sounds quite logical, quite right. But only from a distance! If you move closer in order to see the reality in detail, you'll find that there is another very different picture. True, I was devilishly impatient with those who wouldn't heed my advice. But my reaction was not disgruntlement. In fact I naively fought back, becoming a thorny provocateur. The truth is that I was having fun with the whole dirty business.
Ironically, in the end, ISABELLE's continued downhill slide came to liberate me. I got on with my life and built a highly varied career, not only in science but also in government management, education, science community work, writing and now university teaching. In short, I happen to be a happy man. As for my book, wanting to try my hand at generating one, I opted to write about a major part of my professional life. In doing so, and sticking to the principles I was brought up with, my story tells it like it was.
Mel Month.