Accelerating Neutrons

[Excom]

Main Question or Discussion Point

Hi, is there anyone that can tell how neutrons are accelerated for experimental use.

 

[humanino]

Hi, and welcome to PF

neutrons basically can not be accelerated. You need a neutron source. Roughly, you take huge nuclei, throw bunches of high-energy (so-called spallation) smaller guys, then somehow getting rid of anything charged you end up with only neutrons going out of your source.

http://www.mrl.ucsb.edu/~pynn/primer.pdf [Broken]

 

[Astronuc]

Hi, is there anyone that can tell how neutrons are accelerated for experimental use.

Neutron beams may be generated 1) from nuclear reactors, but there is a broad spectrum of energies, 2) from fusion reactions, e.g. d+t -> alpha (3.5 MeV) + n (14.1 MeV), or 3) from spallation (p,n) reactions, in which accelerated protons are used to knock neutrons out of nuclei.

 

[Vanadium 50]

That said, what people often do is accelerate beams of deuterium (one proton + one neutron) and beams of protons, and subtract the off the proton measurement. It's not quite the same as a beam of neutrons, but it's close.

 

[Excom]

Thanks for the answers.

 

[pam]

You can accelerate deuterons into a thin target that strips the proton, leaving a high energy neutron beam.

 

[malawi_glenn]

You can accelerate deuterons into a thin target that strips the proton, leaving a high energy neutron beam.

Do you know what kind of targets one can use for this purpose?

 

[pam]

This paper describes generating a 50 MeV neutron beam:
http://www.fynu.ucl.ac.be/themes/he/cms/neutron_beam/neutrons-beam.html.

Higher energy neutron beams are now produced at Los Alamos. A paper with this beam is:
Phys. Rev. C 75, 031001 (2007). They describe it as:
"At the LANSCE-WNR facility at the Los Alamos National
Laboratory, a pulsed neutron beam is produced by an 800-MeV
proton beam incident on a 7.5-cm-long water-cooled tungsten
spallation target."
This neutron beam experiment finally confirms theoretical predictions from 1972.