Message In a Bottle


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The new ring is desktop sized

When it comes to do-it-yourself, some people aren't content with merely assembling bookshelves or twisting a coathanger to provide a quick-and-dirty solution.

It all started when Professor Daniel Zajfman of the Weizmann Institute's Particle Physics Department consulted with his German colleagues at the Max Planck Institute. He and his team were using an enormous ring in Heidelberg for storing molecular ions and cooling them to their ground state.

"Two years ago, I came back from a trip to Germany thinking 'Wouldn't it be terrific to have our own machine?'" says Zajfman, who was made associate professor last year. So with his sights set on the 56-meter ion storage ring, he returned to the Institute and created his own version ­ that fits on a desktop.

The research into molecular ion collisions carried out by Zajfman provides vital information about the birth and composition of stars. Zajfman's job: to return ions to their ground state, i.e., the lowest energy and least vibrating state in which a particle can exist. This greatly enhances Zajfman's data on the structure and dynamics of molecular ions, and is of particular interest to astro-, plasma and planetary physicists.

However, with only one week's use of the German ring every few months, there was tremendous pressure to perform only those experiments whose success was practically guaranteed. Being in possession of some kind of device in Israel to which he could have unlimited access would greatly ease the strain.

It took Zajfman-as-problemsolver three months to determine the parameters of how and exactly what to build, given that his small lab could not accommodate a huge 56-meter ring. And what of cost? Ouch: in the region of millions of dollars. What he eventually designed turned out to be a brand new type of ion storage device, the 50-centimeter-long electrostatic bottle.

The bottle, whose price tag is tens of thousands of dollars ­ rather than millions ­ is comprised of two mirrors which bounce the molecular ions back and forth. "It doesn't perform in the same way as the large ring," explains Zajfman, "but it stores molecular ions so that you can cool them."

There is only one such device in existence today, and Zajfman has just begun his first experiments using it. This bottle could also be a boon for others who wait months for beam time on the storage ring at Heidelberg or the only other such rings in the world, in Japan, the U.S., Sweden and Denmark.

Having his own ion storage bottle has not actually meant that the Belgian-born Zajfman (who made aliyah in 1979) has stopped his regular pan-European flights. His collaboration with German physicists is very valuable, and certain experiments, e.g., involving collisions between molecular ions and electrons, still require the large and expensive devices found only at the Max Planck facility. But with equipment "at home" in the lab, he can now attempt, freely, procedures whose results are less predictable.

"If you have a big machine and you only have one beam time every few months, you're not really going to try crazy ideas because of the price and the great effort," he says. "On a small machine you can try crazy stuff. For physicists, crazy things are what make things happen."