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  • Gregory Loew

Some of my memories of Burt Richter

Updated: May 10


I started to work for Project M in 1958 (later to become SLAC in 1962) around the time Burt was developing his electron-electron colliding beam rings at HEPL but we didn’t really meet until the construction of the linear accelerator was completed in 1966. By that time, Burt was at SLAC leading Experimental Group C and beginning to use the linac electron beam for experiments. Together with other pioneering physicists like Richard Taylor, Robert Mozley, Joe Ballam and Martin Perl, Burt was an assertive defender of his turf, making absolutely sure his group would get the best possible beams from the machine we had built and were operating. Sometimes he wasn’t an easy customer!

Meanwhile, Burt had not given up on his dream to construct an electron-positron colliding beams machine that would be supplied by particles from the linac. Unfortunately, he submitted his proposal to the AEC year-after-year without success: the project was too daring and the funding requested, about $20 Million, was too high. In the end, Pief Panofsky saved Burt by making him downsize his design with a much less expensive single ring called SPEAR that could be built as an equipment project out of existing SLAC funds. SPEAR was completed in record time, and people in my Accelerator Physics Department and Karl Brown helped with the construction and operation of the two injection lines from the linac to the single ring.

In November of 1974, Burt’s group with his LBNL collaborators struck gold at SPEAR with the discovery of the J/psi particle. It was a huge accomplishment for the lab. I vividly remember Burt’s speech in 1976 to the entire lab staff standing in front of the cafeteria the day he received the announcement of his Nobel Prize together with Sam Ting at Brookhaven. In typical Burt fashion, he thanked everybody for their help but said he was delighted, however, that it was he who had gotten the prize!

Two years then went by, Burt took a sabbatical at CERN and as separately related by Nan Phinney, he talked the physicists there into building the electron-positron collider LEP to explore Z-physics. When he returned to SLAC, for a short period he thought of proposing two very large electron-positron rings that would extend underground in Menlo Park. Among other ideas, he asked me and my department to restart our superconducting RF project with Perry Wilson which we had abandoned for the linac in the early 1970’s. Burt wanted us to build superconducting accelerating cavities for his two rings. With some pessimism we restarted the project, but fortunately a few months later, Burt came up with a different idea: the SLAC Linear Collider or SLC.

The SLC turned out to be a gigantic challenge. In the mean time, I had become deputy director of the SLAC Technical Division under Richard Neal, and when he turned 65, he stepped down and Panofsky put Burt in his position. As a result, Burt became my boss. The SLC then went from crisis to crisis. It started with the discovery of single-bunch beam breakup in Sector 1 which necessitated a new focusing system and new single-bunch beam position monitors that had to be deployed along the entire linac. Then came the endless difficulties with the two damping rings, the new positron source in Sector 19, the terrain-following arcs at the end of the machine, the final focus, and so on.

One problem Burt assigned specifically to me was to see how we could boost electron and positron beam energies to about 50 GeV each after they emerged from the two damping rings. The total energy of the linac at the time was just 32 Gev. It achieved this by using 30 MW, 2.5 microsecond pulse peak power klystrons in concert with the SLED power compression scheme installed in the 1970’s. To get to 50 GeV required new klystrons with a peak power of at least 50 MW and a longer pulse of 5 microseconds. This was a huge technological quantum jump with which the Klystron Department under Jean Lebaqz and Gerry Konrad struggled for almost three years. Success didn’t come easily: the new klystron gun would break down under high voltage and the klystron ceramic vacuum window would fail from punctures. Burt was getting very anxious. I distinctively remember a crucial meeting when klystron engineer Randy Fowkes stated that it might be impossible to solve the problem without splitting the klystron power in two and placing two separate windows at its output before recombining it to feed the accelerator. Without the least hesitation, Burt jumped on this daring idea and instantly ordered us: “Go for two windows!” even though it wasn’t at all obvious this would work. What followed was a complicated story that ended well. The gun breakdown was solved by going to a higher peak power of 64 MW and a shorter ~4.5 microsecond pulse, and the window problem was eventually solved by installing two vertical ceramic windows so that dust (whose discharge produced the punctures) would fall to the edge where the rf fields were too low to make trouble! Two or three years later, equipped with 240 new klystrons, the linac was able to produce 48 GeV electron and positron beams, enough to reach the Z-mass in collision!

It wasn’t until mid 1989 that many of the other SLC problems were gradually resolved and that the first linear collider in the world began to make Z’s. The Mark II collaboration published its first results in October of that year in PRL. During all this time, I interacted with Burt daily, but unlike him, on weekends I would not attend the momentous 8 o’clock Main Control meetings, preferring to sleep in. He was more tenacious, as we all know.

Starting around 1985 and into the 1990’s, Burt thought that the SLC was just the beginning of a series and he encouraged many of us to develop plans for the Next Linear Collider. I got involved in high-gradient accelerator studies with my then-student, Juwen Wang, and Ron Ruth with a large group built the NLCTA where we tested many new X-band frequency structures and systems. All this work became internationalized, led to collaborations with the Russians at BINP in Novossibirsk, the Japanese at KEK in Tsukuba, the Europeans at CERN in Geneva and at DESY in Hamburg. It required numerous annual meetings in the US and abroad that Burt, David Leith, Ewan Paterson and I attended with many other colleagues. It was as a result of all these collaborations and comparative studies that I was then asked to lead the two International Linear Collider Technical Reviews in 1994-1996 and 2001-2003. Lots of fascinating work and miles on United Airlines!

One not-so-minor side effect of all these collaborations was that in 1994, we learned that the Emperor and the Empress of Japan would come to visit SLAC to see the SLC and the SLD detector. My having had some prior experience in this business with foreign and domestic dignitaries, Burt put me in charge of organizing the event. This was quite an adventure which took a month of preparations. The director of KEK, Hirotaka Sugawara, arrived a couple of days early to help us with the dress rehearsal. Among the many details to which we had to attend, we had to provisionally plug the myriads of holes on the floor around the SLD so that the Empress and her suite of ladies would not get their heels stuck in these holes. Another rule that the Japanese Chief of Protocol imposed on us was that the Emperor and Empress could not descend into the SLD pit with anybody except him and the operator (a SLAC physicist) in the elevator. We of course acquiesced but fate had it otherwise. Just a few minutes before the Japanese delegation entered the Collider Hall, the elevator operator panicked and locked out the elevator. There being no locksmith available, the elevator became inaccessible. As a result their Majesties never got down to the SLD pit and we had to improvise a photo-op and gift ceremony upstairs. Burt kept his cool and acted as a perfect guide and statesman on the occasion. The visit was a total success.

Finally, one other pleasant interaction I had with Burt during all these years had to do with a side-job I ran at SLAC as coordinator for electric power procurements for the lab. The SLC was a power hog (over 60 MW if I remember correctly) and it could cost a fortune which the lab didn’t have. Fortunately, the electric power consortium we had formed with LBNL and LLNL was very effective in buying cheap wholesale power from the Western Area Power Administration (WAPA) and a private company in Oregon. Thanks to this consortium, I would be able to surprise Burt by considerably lowering SLAC’s power bill. Burt wanted to think it was all my doing (which it wasn’t) and he had no end of compliments for me every time I would bring him good news, which of course was very flattering.

It’s difficult to imagine SLAC without Burt being around!

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