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Novel materials and concepts for Neutron Image Plates

Michael Schlapp 1,2Alexander Ioffe 2Sergey Masalovich 2Harald Conrad 2Thomas Brückel 2Hartmut Fuess 1Heinz Von Seggern 1

1. Technische Universität Darmstadt, Institute of Materials Science, Petersenstr. 23, Darmstadt 64287, Germany
2. Forschungszentrum Jülich, IFF, Streumethoden, Jülich 52425, Germany


Neutron image plates (NIPs) provide the means for two-dimensional, position-sensitive detection of neutrons. Commercially available NIPs consist of a mixture of the neutron converter Gd2O3 and the storage phosphor BaFBr:Eu2+, dispersed in an organic binder supported by a flexible sheet. Since BaFBr is an excellent storage phosphor for X-rays, these NIPs are prone to the γ-background always present at neutron experiments. In this contribution we present a system of converter (6LiF) and storage phosphor (KCl:Eu2+ or KBr:Eu2+) which shows a high efficiency for the detection of neutrons while at the same time features a low γ-sensitivity due to the low atomic numbers. It was found that storage phosphors mixed with LiF feature a signal per absorbed neutron that is twice as high as those samples containing GdF3 as converter. This advantage results from a much higher usable energy output of LiF after a neutron absorption reaction. Combining the large signal with the γ-absorption of KCl, which amounts to about 10% of BaFBr, one obtains a neutron equivalent for KCl:Eu2+-6LiF image plates of 1/20 neutron per photon for soft γ-rays (< 300 keV) while the equivalent for hard γ-quanta (>300 keV) is 1/400 neutron per absorbed photon.
Three different morphologies of NIPs were fabricated based on KCl:Eu2+-LiF: polymer supported (P-NIPs), ceramic (C-NIPs) and pixelated (Pix-NIPs) neutron image plates. Pix-NIPs represent a novel morphology in which the scattered light is confined to the cell of a honeycomb structure embedded in the image plate. Due to this confinement, the resolution of such an image plate is primarily independent of scattering properties of the NIP and is primary a function of the size of the honeycomb structure used.
Determining the Detective Quantum Efficiency DQE for a C-NIP consisting of KCl:Eu2+-6LiF resulted in a value of 38 % which corresponds to an efficiency comparable to commercially available NIPs.


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Presentation: invited oral at E-MRS Fall Meeting 2004, Symposium D, by Michael Schlapp
See On-line Journal of E-MRS Fall Meeting 2004

Submitted: 2004-04-06 16:35
Revised:   2009-06-08 12:55