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X-Ray Detector, Cross Grid, Developmental "Bread Board Model"


Display Status:

This object is on display in the Explore the Universe exhibition at the National Air and Space Museum in Washington, DC.

Collection Item Summary:

This is an imaging x-ray detector built by Steve Murray in the early 1970s as part of his PhD research program in 2-dimensional imaging techniques. Under the direction of Riccardo Giacconi, he laboriously hand wound this breadboard model to show that his "cross-grid" design was viable. The copper wire grid is wound in two orthogonal layers and is part of an electronic circuit that is sensitive to incoming electrons. To make it detect x-rays, Murray placed what is called a microchannel plate on top of the grid. Incoming X-rays from a hot source would first hit the front of the microchannel plate and be converted into electrons. The microchannel plate then amplified the resulting electronic charge producing a stream that then hit the dense grid of very fine wires on the detector. The intersections of the wires in the two layers define the x and y coordinates of the charge stream. The resulting signal is used to construct images of the sources of original X-ray pattern. The proof of principle provided by this breadboard detector led to the high resolution X-ray imagers used on orbiting X-ray observatories including HEAO-2 (Einstein), ROSAT, and AXAF (Chandra).

It was transferred to NASM from SAO in 2002.

Collection Item Long Description:

Data Source

National Air and Space Museum


Do not reproduce without permission from the Smithsonian Institution, National Air and Space Museum

Credit Line

Transferred from the Smithsonian Astrophysical Observatory, Harvard University.


  • Plastic
  • Electronics


3-D: 12.7 × 10.2 × 2.2cm (5 × 4 × 7/8 in.)

Country of Origin

United States of America



Inventory Number