Document Details
PURL
(491 K)
Title:
PINEX: The pinhole neutron experiment
Author(s):
Document Type:
REPORT
Publication Date:
1958 Nov 21
Declassification Date:
1996 Feb 22
Declassification Status:
Declassified
Document Pages:
10 p.
Accession Number:
OOL20100215
Document Number(s):
UCRL-ID-124986
Originating Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
OpenNet Entry Date:
1997 Feb 13
OpenNet Modified Date:
2022 Nov 30
Description/Abstract:
The pinhole neutron experiment is sometimes called ``Pinex``, a name which has also been used to describe the pin method of measuring the time required for imploding metals to travel to certain locations in space. The two experiments are not related and should not be confused with each other. The pinhole neutron experiment is very similar to the optical pinhole camera in which light passing through a pinhole in an opaque screen produces an inverted image of the source. In the pinhole neutron experiment 14 Mev neutrons from a thermonuclear device travel in straight.lines from their respective points of origin outward in all directions. Those which pass through a pinhole in an opaque neutron shield make an inverted neutron image of the source. Some of the neutrons which form the image are captured by threshold detector plates which have been suitably located behind the pinhole. Neutrons that have sufficient energy react with the nuclei of the detector plate to form radioactive nuclei that by their decay locate the position of the image on the plate. The image may be made visible by autoradiography or counting techniques. In the autoradiograph, an x-ray film is placed in contact with the image plate. As the radioactive nuclei decay, they expose the film. The image is visible when the film has been adequately exposed and developed. In the counting method, the image plate is cut into small pieces; each the size of a resolution element. Each piece is separately counted. The number of neutrons causing its radioactivity is determined and plotted on a drawing of the plate. These numbers indicate the shape of the D-T plasma at the time of ``burn``. It is the object of this paper to discuss the factors affecting the various parameters in the experiment and what information is required to optimize these parameters for a given set of conditions. Formulae are written in many alternative ways to emphasize the effect to be expected from a change in any one of the many parameters.