PASER: New Electron Acceleration Technique Developed

Newswise — For the first time, scientists have demonstrated a laser-like transfer of energy—without the laser light—to an electron beam. The technique developed at the Technion-Israel Institute of Technology produces accelerated particles that could have future applications in fields as diverse as medicine and probing the fundamental structure of matter.

The electron acceleration technique is called PASER, an acronym for Particle Acceleration by Stimulated Emission of Radiation. Its first experimental demonstration will be published in the 29 September issue of the journal Physical Review Letters. The theoretical concept behind the PASER was first proposed in 1995 by Professor Levi Schächter, leader of the Technion's PASER group that includes Dr. Samer Banna and Dr. Valery Berezovsky.

At its most basic level, the technique involves passing a modified electron beam through a cavity filled with excited carbon dioxide (CO2) molecules, creating millions of tiny collisions between the CO2 molecules and each electron in the beam.

In a laser-type scheme, the energy produced by these collisions would be released in the form of light particles called photons that gather together to produce the familiar colored laser beam. In the PASER scheme, demonstrated recently by the Technion's PASER group using facilities at the Brookhaven National Laboratory in Upton, NY, the energy is transferred directly to the electron beam in a coherent way, producing accelerated electrons but no heat.

Banna says future applications of the PASER scheme would be mostly the same as any current high-energy particle accelerators, "in a reliable and compact form."

For instance, PASER particle acceleration could produce high quality X-ray probes for use in medicine and nanotechnology. However, Banna stresses that the PASER technique may be half a decade or more from practical applications.In future experiments, the PASER group hopes to boost the particles' acceleration rate, which would bring it closer to practical applications.

According to Banna, a key aspect of the experiment was the modification of the electron beam before it entered the CO2 cavity, which could only be done with the help of a powerful CO2 laser at the Accelerator Test Facility at the Brookhaven National Laboratory. The Technion researchers used the laser and a series of magnets to slice up the beam into a train of smaller electron packets and adjust them to a specific energy and timing to take maximum advantage of collisions within the cavity.

The Technion-Israel Institute of Technology is Israel's leading science and technology university. Home to the country's winners of the Nobel Prize in science, it commands a worldwide reputation for its pioneering work in nanotechnology, computer science, biotechnology, water-resource management, materials engineering, aerospace and medicine. The majority of the founders and managers of Israel's high-tech companies are alumni. Based in New York City, the American Technion Society is the leading American organization supporting higher education in Israel, with 17 offices around the country.