[Fast-Neutrons] Congrats! Re: First fast neutron images at Phoenix
Burkhard.Schillinger at frm2.tum.de
Mon Nov 18 08:41:01 CET 2019
congratulations for these nice images!
For a fast neutron image, that resolution is pretty good. Probably
better than ours - which shows that a high collimation is also
important for fast neutrons if you have large samples.
I am also surprised again by your thermal image at L/D of only 35 -
but that's what you get when you can put the samples up close to the
For an edge - about everything scatters fast neutrons, but I have
tried with a 10 mm thick polyethylen pattern (Siemens Star) that was
3D printed at our lab. When putting it directly on the detector, it
was a good measure to test the screen. The 1.5 mm thickness screen was
much better than the 2.4 mm.
Not sure what really happens if you take it further away - I assume
that 10 mm thickness is a good compromise between attenuation and
scattering blur. You might try 10 mm steel as well, but iron is also a
A perfect edge does not exist.
Good luck with your new 'toys', and Happy Holidays!
> Good day to all,
> I am happy to announce that we've taken our first fast neutron
> images at the Phoenix facility in Wisconsin, USA! Our source is
> operational now with a source strength of approximately 1.5e12 n/s
> and an L/D of 450 to achieve a flux at the image plane of
> approximately 5e5 n/cm^2-s. Over the next few weeks, we will be
> increasing our beam current and changing our target to a different
> material. We expect to get to full power and have a source strength
> of 3e13 n/s and a flux at the image plane of approximately 1e7
> The image attached was taken using a Varex XRD 1621 digital detector
> array and a PP:ZnS(Cu) screen provided by RCTritec. The
> scintillator field of view is 310mm x 310mm, but we plan to use the
> full field of view of the detector eventually, which is 430mm x
> 430mm. The image was taken last night and acquired with 15 frames
> at 20 seconds each. The frames were then added and the offsets were
> applied for background corrections. The sample is a simulated M982
> military round. It is 155mm in diameter. The outside casing is
> 1/8" steel and the inside simulant is an HMX equivalent, 6% 6656
> binder (simulated with 204 epoxy). Chemically it is similar to HMX
> and RDX but with much less nitrogen. I have outlined some of the
> defects of interest that we want to see.
> We would like to measure the resolution of the system next so I
> would like to ask if anyone has advice on what material to use as an
> edge and how thick it should be? We do not yet have any kind of
> standard measurement technique for this that I'm aware of, so I
> would like to know what others are doing.
> I've also attached a new image we acquired using thermal neutrons of
> several different military grade .50 caliber ammunition. We took an
> X-ray image for comparison and that is shown as well. The X-ray was
> done at 350kV but I don't recall the current. The neutron image was
> acquired using our thermal neutron generator with heavy water
> moderator, the L/D was 35 and the flux was approximately 1e4
> n/cm^2-s. The exposure time on a neutron sensitive image plate was
> 20 minutes.
> I hope everyone is well, it was great to meet so many of you in
> Garching last month and I wish you all happy holidays as they
> approach us soon.
> Best regards,
> Michael Taylor Ph.D.
> Neutron Radiography Product Manager
> Phoenix LLC
> 2555 Industrial Drive
> Madison, WI 53717
Dr. Burkhard Schillinger
Technische Universität München - FRM II
Heinz Maier-Leibnitz Zentrum
Tel. +49 89 289-12185
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