[Fast-Neutrons] Congrats! Re: First fast neutron images at Phoenix

Mon Nov 18 12:17:04 CET 2019

OK, perhaps Fuji now produce more efficient neutron imaging plates. I only
know that we have used Fuji plates at ILL for 25+ years for Laue
diffraction and had great difficulty persuading Fuji, with the help of a
famous Japanese scientist, to make special high efficiency plates for us.
The market is very small, so Fuji just converted ordinary x-ray plates to
their commercial neutron product. Those commercial plates were less
efficient and also had magnetic backing to stick to a support, not ideal
for neutrons.

I would be interested in a comparison of images with an image plate, a
photographic film in contact with a scintillator, a CCD camera, and a flat
solid state detector. The latter is also developed for x-rays, contains
materials that are activated by neutrons, and as Eberhard says, may be
damaged by the beam.

Alan
______________________________________________________
   Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE
                               from my telephone
<Alan.Hewat at NeutronOptics.com> +33.476.98.41.68
        http://www.NeutronOptics.com/hewat
______________________________________________________

On Mon, 18 Nov 2019, 11:52 Lehmann Eberhard (PSI), <eberhard.lehmann at psi.ch>
wrote:

> 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 …
>
>
>
> Regards
>
>
>
> Eberhard
>
>
>
> __________________________________________
> Paul Scherrer Institut
> Dr. Eberhard H. Lehmann
> WBBA/122
> Forschungsstrasse 111
> 5232 Villigen PSI
> Schweiz
>
> 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> +33.476.98.41.68
>         http://www.NeutronOptics.com/hewat
> ______________________________________________________
>
>
>
> On Mon, 18 Nov 2019, 08:42 Burkhard Schillinger, <
> Burkhard.Schillinger at frm2.tum.de> wrote:
>
> Hello Michael,
>
> 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
> detector.
>
>
> 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
> diffuse scatterer.
> A perfect edge does not exist.
>
> Good luck with your new 'toys', and Happy Holidays!
>
> Burkhard
>
>
>
>
> > 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
> > n/cm^2-s.
> >
> > 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
> >
> > Michael Taylor Ph.D.
> > Neutron Radiography Product Manager
> > Phoenix LLC
> > 2555 Industrial Drive
> > Madison, WI 53717
> > 608-515-3214
>
>
>
> --
> Dr. Burkhard Schillinger
> Technische Universität München - FRM II
> Heinz Maier-Leibnitz Zentrum
> Lichtenbergstr.1
> D-85748 Garching
> Germany
> Tel. +49 89 289-12185
>
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>
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