First Neutron Pulse from SNS

kebes writes "The $1.4 billion Spallation Neutron Source is nearing completion, and has produced its first neutron pulse. The SNS is a scientific instrument that generates beams of neutrons, which can be used to probe anything from minuscule samples to industrial materials. When fully operational, the facility is expected to host up to 2,000 international scientists annually."

Comments

Re:How do they make a pulsed neutron beam?

[CaryTheSane]

IANAPP (I am not a Particle Physicist) but I *DO* work at the SNS site. I'm a software engineer in their Beam Diagnostics group, and was in the contorol room on Friday when we met this milestone. My basic understanding is that here we use our Linac to accelerate protons (H-). A minipuse sent down the linac is approx 700 ns long. They first go into an accumulator ring, and are "stacked" to increase the intensity of the pulse to target. On Friday we accumulated for around 180 pulses, design specs are for around 1000. Finally the the pulse is extracted from the ring and hits a target vessel filled with mercury. Again, IANAPP, but my understanding is that this intense pulse of protons only 700 ns long, hits the mecury, and "spalls" neutrons from the mercury atoms. Then as others have mentioned the neutrons are columnated and fly down different beam lines to be used in different refraction experiments (or they will be once this source is fully operational ;-) . Bottom line is that the particles that we acclerate are not the ones that contribute neutrons. Once more, IANAPP, but it helps me to think of it as we're accelerating cue balls, and hitting a (3D) rack of billard balls.

Re:Pyroelectric Fusion as Neutron Source?

[SlashSquatch]

Yep. The pyroelectric crystal can produce about 1000 neutrons per second. This spallation accelerator produces 1.5e10^14 protons per pulse. Each proton should generate 20-30 neutrons. Evidently this source is supposed to be brighter. If I estimate correctly, brighter by an order of 10^10 times.