[Fast-Neutrons] [EXTERNAL] Re: Congrats! Re: First fast neutron images at Phoenix
Aaron E. Craft
aaron.craft at inl.gov
Fri Jan 10 00:42:26 CET 2020
Sorry for the slow response - I just returned to work this week after five weeks of recovering from ankle surgery and being out of the office.
I would be happy to lend you a Siemens star. I can bring it with me to the upcoming ASTM meeting. Sound good to you?
Aaron E. Craft, Ph.D.
Characterization & Advanced Post-Irradiation Examination Division
Idaho National Laboratory | PO Box 1625 | Idaho Falls, ID 83415
Phone: 208-533-7673 | Cell: 208-201-4242
Aaron.Craft at inl.gov
From: fast-neutrons-bounces at neutronsources.org <fast-neutrons-bounces at neutronsources.org> on behalf of Michael Taylor <Michael.Taylor at phoenixwi.com>
Sent: Thursday, December 12, 2019 1:49 PM
To: Lehmann Eberhard (PSI) <eberhard.lehmann at psi.ch>; Alan <alan.hewat at gmail.com>; fast-neutrons at neutronsources.org <fast-neutrons at neutronsources.org>
Subject: [EXTERNAL] Re: [Fast-Neutrons] Congrats! Re: First fast neutron images at Phoenix
Does anyone already have a printed Siemens star they'd be willing to ship to me for testing? Has anyone come up with another method for measuring resolution for fast neutron imaging? We are otherwise going to image an edge on different pieces of material: Fe, W, Cu, Al, HDPE to see how they compare.
From: fast-neutrons-bounces at neutronsources.org <fast-neutrons-bounces at neutronsources.org> on behalf of Lehmann Eberhard (PSI) <eberhard.lehmann at psi.ch>
Sent: Monday, November 18, 2019 4:52 AM
To: Alan <alan.hewat at gmail.com>; fast-neutrons at neutronsources.org <fast-neutrons at neutronsources.org>
Subject: Re: [Fast-Neutrons] Congrats! Re: First fast neutron images at Phoenix
I disagree with Alan about the n-sensitive imaging plates: they are
made by Fuji on a commercial base adding Gd to the X-ray sensitive
material. Therefore the efficiency is not bad and much better than
film methods …
Paul Scherrer Institut
Dr. Eberhard H. Lehmann
5232 Villigen PSI
Telefon: +41 56 310 29 63
E-Mail: eberhard.lehmann at psi.ch
Von: fast-neutrons-bounces at neutronsources.org <fast-neutrons-bounces at neutronsources.org> Im Auftrag von Alan
Gesendet: Montag, 18. November 2019 10:43
An: fast-neutrons at neutronsources.org
Betreff: Re: [Fast-Neutrons] Congrats! Re: First fast neutron images at Phoenix
Hello Michael, Burkhard and Eberhard.
Thank you Michael for these nice images. I too am impressed by the resolution of your thermal images with an L/D of only 35, and agree that it would be good to take thermal images with a camera rather than a neutron image plate. The ordinary Fuji n-plates are just x-ray plates with extra 6LiF and I think only ~10% efficient. ~20 years ago Fuji made special n-plates for ILL that were ~25% efficient but they are no longer available (?). You should be able to reduce the exposure well below 20 minutes with a camera and a good 6LiF/ZnS thermal neutron scintillator even with only 10**4 n.cm-2.s-1. See the images Robert Zboray showed in Sydney from a very low flux Triga reactor, one of which I reproduced in my Munich talk.
It would also be good to compare your fast neutron image with a thermal neutron image using the same detector and L/D (with different scintillators). With such small objects, that can be put close to the scintillator, it would be interesting to see if fast neutrons still have some advantage for imaging such defects.
I also found Burkard's and Eberhard's comments about the best material and thickness for a fast neutron Siemens star interesting. It would be good to see images with these different resolution objects. I also printed a plastic Siemens star, but 40 mm thick, which I have not yet been able to test. A final trivial point; please don't use exponent e4 instead of 10**4 for flux; e has a different meaning for mathematicians.
Thanks again for sharing. Alan
Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE
from my telephone
<Alan.Hewat at NeutronOptics.com<mailto:Alan.Hewat at NeutronOptics.com>> +33.4188.8.131.52
On Mon, 18 Nov 2019, 08:42 Burkhard Schillinger, <Burkhard.Schillinger at frm2.tum.de<mailto:Burkhard.Schillinger at frm2.tum.de>> wrote:
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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