Thursday, November 23rd, 2017

Smashing atoms

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The God Particle – 8

Chapter 6: Accelerators: They Smash Atoms, Don’t They?

The mammoth underground rings that “smash” atoms are called particle accelerators, and they can cost billions. This poses a challenge to congress when they are asked to fund them. For example, in a fragment of conversation between Senator John Pastore and Robert Wilson, the Senator asked if the planned accelerator “in any way involves the security of this country.” Wilson answered, “It has nothing to do directly with defending our country except to make it worth defending.” Good answer, I think, but perhaps not too helpful in convincing those controlling our country’s purse-strings.

Our author, Dr. Lederman, directed Fermilab near Chicago with its 4-mile circumference accelerator. He tells us a little bit about accelerators.

I sometimes think about the tower at Pisa as the first particle accelerator, a (nearly) vertical linear accelerator that Galileo used in his studies. However, the real story starts much later. The development of the accelerator stems from our desire to go down into the atom. Galileo aside, the history begins with Ernest Rutherford and his students, who became masters of the art of exploiting the alpha particle to explore the atom.

In a philosophical digression, he wonders if God “is making this up as she goes along.” The history of the first particle accelerator from the time of Rutherford to the present is one of larger and larger accelerators, one after another. “Large” for an accelerator is measured in electron-volts (eV), which has increased from 5 million eV (tiny!) to 40 trillion uV for the Superconducting Super Collider. For details, read the darn book for yourself.

The electron volt is a measure of energy. When you strike a match, you release aout 10 eV. By the time you get to the God Particle, you are talking energies of ten-trillion eV, or something like that. One accelerator, like Fermilab in 1972, may accelerate protons to something like 99.999% of the speed of light, with an energy of 200 Giga-eV.

One goal of this book is to give us an appreciation of experimental physics. Here is one way Lederman explains it.

In a Fermilab education program for ten-year olds, we confront them with this problem. We give them an empty square box to look at, shake, weigh. Then we put something in the box, such as a wooden block or three steel balls. Then we ask the students again to weigh, shake, tilt, listen, and to tell us everything they can about the objects: size, shape, weight . . . It’s an instructive metaphor for our scattering experiments. You’d be surprised how often the kids get it right.

As we accompany our author through the development of larger and larger accelerators, we learn about items like the cyclotron and the synchroton and what Lederman calls Big Science and the California Mystique. You don’t have to be a science nerd to find this interesting, thanks to his breezy style and sense of humor.

Dave

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