A Quantum Diaries Survivor

Dr. Lederman, the luckiest Nobel prize winner July 13, 2008

One of the many good things of being on vacation is that I find the time for light reading. No, not novels – those take too much time! I mean books that, in a way or another, have something to do with my job, but have nonetheless rested on a waiting list for months.

One such book, which accompanied me to Sardinia, is “The Rise of the Standard Model“, by L. Hoddeson, L. Brown, M. Riordan, and M. Dresden (eds.), Cambridge UP 1997. It is a collection of pieces from the main characters in the history of the discoveries that brought, during the sixties and the seventies, to the universal acceptance of the unified theory of electroweak interactions and its merging with strong interactions.

Today, laid on a reclining chair on the side of the pool where my kids kept swimming like little fishes for a whole afternoon, I enjoyed reading Leon Lederman’s contribution, centered of course on the discovery of the fifth quark. In it, Leon comes clean with his belief -which I totally share- that a successful discovery in particle physics requires as the main ingredient a disproportionate amount of luck.

Leon explains that the discovery of the Upsilon mesons -particles decaying to pairs of muons which were immediately recognized in 1977 as bound states of a new quark-antiquark pairs- was done twice: the first time when he and his colleagues were fooled into dubbing “Upsilon” a pile of background events eerily piling up at a reconstructed mass of 6 GeV. He also readily explains, with a good display of modesty, that by the time he got convinced that what had initially appeared as another fluctuation at 9.5 GeV was really a new resonance, a bottle of Mumm champagne with a big “9.5” handwritten on it by “super-postdoc” John Yoh had rested in a fridge for many long months already.

Luck did play a part in Lederman’s Nobel prize. He has been a very skilled and brilliant particle physicist, but for every Lederman there are a hundred unnamed individuals of no less insight and capacity, who lacked the good fortune of being at the right moment in the right place.

In any case what I found most surprising was the very beginning of Lederman’s piece, where he makes the case against himself strong and unrefutable. In 1968, Lederman had been conducting an experiment in Brookhaven which reconstructed the mass of muon pairs in proton collisions against a fixed target. In his own words,

“I was so excited bythe properties of virtual photos that we decided to study them specifically and we set up this ingeniously stupid detector in order to study muon pairs.[…] the simple Brookhaven apparatus was so dumb that there was no way you could change it to improve the resolution even a little bit. Every element was designed to match the distorsions generated by multiple scattering in ten feet of steel. This took a minimum of thought, so no matter what you did you were stuck with 15% resolution.”

The lousy mass resolution turned thousands of J/Psi meson decays to dimuon pairs resonating at 3.09 GeV into a broad, featureless shoulder in a falling mass distribution:

“I think that after the shock of seeing Ting’s data, I sent around a note saying that any apparatus that can convert this towering peak to our mound of rubble should be proscribed by SALT talks.”

Lederman had the charm discovery in his own hands six full years before the November 1974 revolution, but he claims he had designed the detector stupidly, and so all he got named after him was a shoulder!

“IF our mass resolution had been 10% […] This experiment, properly carried out, would have produced results that won five Nobel prizes!”

I think this is remarkable! Nature -for once not a bitch- must have liked Leon so much that she gave him a second chance: he had failed her miserably on the fourth quark, but by the time the fifth showed up, he did know better after all.