Wednesday, January 30, 2013

A Laser-Based Table-Top Neutron Source? I'll Take One!

Exciting news for those who depend on neutron sources for to study things. A new development in using high-powered laser to produce energetic neutrons with reasonable flux has been reported.

Neutrons are a valuable tool for scientists in many fields, allowing them to probe the structure and dynamics of a range of materials. Today, the main drawback of neutron science is that intense beams of neutrons must be produced in either nuclear reactors or dedicated accelerator facilities – making a laser-based table-top source very attractive.

This scheme has now been put into practice by Markus Roth of the Technische Universit├Ąt Darmstadt and colleagues at Los Alamos and Sandia National Laboratories. Roth's team directed extremely powerful and well defined pulses from the Los Alamos TRIDENT laser onto a 400-nm-thick plastic target doped with deuterium atoms. This was positioned just 5 mm in front of a secondary target made from beryllium.

Even though the pulses delivered less than a quarter of the energy employed in previous experiments, they produced neutrons that were nearly 10 times as energetic – up to 150 MeV – and also nearly 10 times as numerous. In addition, many of these neutrons were emitted in the forward direction, which the researchers attribute to one specific kind of nuclear reaction, the break-up of deuterons.
This has the potential to either replace, or supplement spallation neutron sources. There's still a lot of work to be done, but it looks like this could make having neutron source for material study as easily has having x-ray sources for such a study. Of course, we haven't considered the safety issues here since neutrons are significantly more dangerous to deal with here.


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