Monday, July 06, 2009

Scientists Work on New Particle Accelerator

This news report describes the planned upgrade of the laser plasma wakefield accelerator at Berkeley Nat'l Lab.

Researchers at the Berkeley Lab plan to use microscopic waves to charge and accelerate some of the smallest particles in the universe.

The process will take place in the lab's "table-top" Berkeley Lab Laser Accelerator, a device that is planned to be built by fall 2009 and will replace the lab's current, smaller accelerator.

Not sure what the article meant as ".. some of the smallest particles in the universe.. " when they can just mention "electrons" and be done with, because that is accurately what the facility will accelerate.

The news report has some rather puzzling statements. For example:

A laser beam will then puncture the gas and cause a "wake" that will accelerate and charge the particle that follows the beam, said Paul Preuss, a member of the communications department for the lab.

The laser will cause the wake, yes, but it also "charge up" the following particle that is being accelerated? It will charge up the gas and turning it into a plasma, but the particles being accelerated, which are electrons, are already "charged"!

In this scheme, a high-powered pulsed laser passes through a cloud of neutral gas. The laser's electric field then ionizes the gas for a split second, creating a region of very high electric field gradient (what the news article kept referring to as creating "charge"). This high gradient is the accelerating gradient that will accelerate an electron bunch that trails after the laser pulse. I've highlighted this technique a while back.

This is such an amazing technique that can achieve quite high gradient. If it can be implemented, the energy ceiling for high energy physics experiments can be raised quite a bit without busting a budget. Too bad the reporting of the physics isn't that clear.


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