By Alice Phillips on February 1, 2012

Scientists at the SLAC National Accelerator Laboratory announced last Wednesday their involvement in an experiment that created the first successful atomic X-ray laser.

Such a laser was predicted to be possible as long ago as 45 years, according to Science Now. The vast amount of energy required for a functioning atomic X-ray laser, however, led past physicists to attempt even nuclear explosions in order to generate the requisite power. SLAC broke through by using the Linac Coherent Light Source (LCLS) laser to power the atomic X-ray laser.

SLAC scientist John Bozek said that the LCLS, which has been operational since August 2009, is the only X-ray free electron laser in the world that would have been powerful enough to power the atomic X-ray laser being tested in the experiment. The $410 million LCLS emits light 10 billion times brighter than other X-rays.

The experiment, which has been in the works for approximately two years, pumped X-rays into a cell of neon gas. The neon molecules’ electrons entered an excited state lasting five femtoseconds(5×10-15 seconds).

“There are as many femtoseconds in a minute as there are minutes in the age of the universe,” Bozek said. “It’s a very small fraction of a second.”

In order to read whether the atomic X-ray laser beam was working, a team of SLAC, Lawrence Livermore National Laboratory (LLNL) and Colorado State University scientists set up a spectrometer downstream of the laser. The spectrometer, which was furnished by Colorado State, was able to measure the intensity of light emanating from the atomic X-ray laser and then display its readings in real-time on a monitor in an instrument room.

“[LLNL and Colorado State] brought in some very different pieces of equipment that we hadn’t used before, including this high pressure gas cell of neon and this X-ray spectrometer– neither of which are exceptionally unique, but we hadn’t used them before,” Bozek said. “It’s an interesting facility in the sense that you’re always doing a new experiment every week.”

For the first three of five 12-hour shifts– or three-fifths of the team’s “beam-time”– the group was not getting the results it was looking for on the monitors, according to the SLAC scientists. The display was only reading one line, whereas a second line on the readout would indicate that the atomic X-ray laser was up and running. When the readings started to match the group’s expectations, the scientists quickly realized the magnitude of their success.

“People were really jumping up from the chairs, saying ‘There it is,’ getting really excited and pointing at the monitors,” said Christoph Bostedt, a SLAC scientist. “It definitely was kind of a moon-landing situation when we saw the first signal.”

Led by lead authors Nina Rohringer, formerly of LLNL and now with the Max Planck Advanced Study Group in Germany, and Colorado State professor of electrical and computer engineering Jorge Rocca, the group published its findings in the Jan. 26 issue of Nature.

“This scheme provides greatly increased wavelength stability, monochromaticity and improved temporal coherence by comparison with present-day X-ray free-electron lasers,” the report stated. “The atomic X-ray lasers realized here may be useful for high-resolution spectroscopy and nonlinear X-ray studies.”

While the scientific community is eager to use the new technology and explore its potential, Bozek said he expects it to be years until anybody begins to fully utilize the atomic X-ray laser in non-preliminary ways.

“We have received proposals that want to take advantage of this,” Bostedt said. “It doesn’t say that they will take advantage of it, but we have received proposals.”

Atomic X-ray laser technology could be applied in materials science, the investigation of dynamics, matter, spectroscopy or in fields that are not known today. For example, traditional laser technology was not invented specifically to read CDs or operate radar, Bozek said. Rather, those applications followed the invention.

“The creativity of scientists is such that somebody is going to come up with a great idea of how we can use it to do something that we haven’t even thought of yet,” Bozek said.

“It’s like we’ve walked through a forest and all of a sudden there’s this beautiful pasture,” he added. “The possibilities are huge, and we don’t even know what they are yet.”