Engineering topics

Reid, P. B.

Publications and source records attributed to Reid, P. B..

8 records

NASA NTRS2014

Development Status of Adjustable X-Ray Optics with 0.5 Arcsecond Resolution

We report on the continuing development of adjustable, grazing incidence X-ray optics for 0.5 arcsec telescopes. Adjustable X-ray optics offer the potential for achieving sub-arcsecond imaging resolution while sufficiently thin and light-weight to constitute a mirror assembly with several square meters collecting area. The adjustable mirror concept employs a continuous thin film of piezoelectric material deposited on the back of the paraboloid and hyperboloid mirror segments. Individually addressable electrodes on the piezoelectric layer allow the introduction of deformations in localized "cells" which are used to correct mirror figure errors resulting from fabrication, mounting and aligning the thin mirrors, residual gravity release and temperature changes. We describe recent results of this development. These include improving cell yield to approx. 100 per cent, measurements of hysteresis and stability, comparisons of modeled and measured behavior, simulations of mirror performance, and the development and testing of conical Wolter- I mirror segments. We also present our plans going forward toward the eventual goal of achieving TRL 6 prior to the 2020 Decadal Review.

Reid, P. B.↗

NASA NTRS2008

Optics Requirements For The Generation-X X-Ray Telescope

US, European, and Japanese space agencies each now operate successful X-ray missions -- NASA s Chandra, ESA s XMM-Newton, and JAXA s Suzaku observatories. Recently these agencies began a collaboration to develop the next major X-ray astrophysics facility -- the International X-ray Observatory (IXO) -- for launch around 2020. IXO will provide an order-of-magnitude increase in effective area, while maintaining good (but not sub-arcsecond) angular resolution. X-ray astronomy beyond IXO will require optics with even larger aperture areas and much better angular resolution. We are currently conducting a NASA strategic mission concept study to identify technology issues and to formulate a technology roadmap for a mission -- Generation-X (Gen-X) -- to provide these capabilities. Achieving large X-ray collecting areas in a space observatory requires extremely lightweight mirrors.

O'Dell, S. .↗

NASA NTRS1991

Fabrication of the first pair of optics for the Advanced X-ray Astrophysics Facility (AXAF)

The first two mirrors for the Advanced X-Ray Astrophysics Facility (AXAF) have been successfully fabricated and tested. The methodology developed has demonstrated figure convergence rates previously unseen on large area, precision optics. These results were based on developing a unified systems approach to fabrication and testing aided by the extensive use of analytical models. This paper presents a summary of the optic requirements, an overview of the fabrication process, the metrology used, and a summary of the results.

Reid, P. B.↗

NASA NTRS1988

Measurement of micro-roughness and effects of detector bandwidth and finite width

Surface micro-roughness of grazing incidence optics has long been recognized as a critical parameter in the control of the scattered X-ray intensity and its effects on the point spread function half-energy width. Accurate knowledge of the amplitude of surface micro-roughness is vital to assess optic predicted performance during the final stages of fabrication. This requires not only a knowledge of the spatial bandwidth over which surface features must be measured, but also knowledge of the bandwidth of the measurement instrument. We show that the standard assumption that instruments respond up to their Nyquist limit is an oversimplification which neglects the finite detector size and its bandwidth limiting effects when sampling a real (i.e., two-dimensional) surface.

Reid, P. B.↗

NASA NTRS1982

An X-ray image of Tycho's supernova remnant

An image of Tycho's SNR has been obtained using the imaging proportional counter aboard the Einstein Observatory, revealing a nearly circular, 8 arcmin, open shell of emission. The X-ray and radio shells are spatially coincident, although there is no correlation in intensity between the two wavelengths. Adopting a distance of 3 kpc, a 0.15-4.5 keV luminosity of 5 x 10 to the 36th ergs/sec is inferred. The mass of the X-ray emitting material is 7-15 solar masses if the SNR is in the adiabatic stage of its evolution. This is consistent with the interpretation that the SNR was the result of a Type I explosion and that the distance to Tycho's SNR is between 2.2 and 4.3 kpc.

Reid, P. B.↗

NASA NTRS1979

A drift multiwire proportional counter for cosmic soft X-ray imaging

Multiwire proportional counters with 1 micrometer polypropylene windows, of dimensions 75 mm x 75 mm and 100 mm x 100 mm, have been built to map soft cosmic X-rays. The counters are constructed with a large drift region which makes it possible to use the center-of-gravity technique to improve the counter's efficiency and position resolution. Using 330 torr of propane as the gas fill and an anode plane composed of 20 micrometer diameter, gold-plated tungsten wire spaced 1mm apart, a position resolution of better than 280 micrometers (FWHM) in two orthogonal directions at an X-ray energy of 0.94 keV was achieved.

Reid, P. B.↗

NASA NTRS1979

Imaging proportional counter for X-ray astronomy

A position-sensitive proportional counter capable of imaging X-rays (0.1-3 keV) over a 10 cm x 10 cm aperture has been constructed. Positioning is obtained by sensing the signals induced by an X-ray event on the two orthogonal sets of cathode wires. Each cathode is divided into a series of cathode strips, each 0.5 cm wide. An X-ray event induces signals on several adjacent strips. Signals from each cathode strip are amplified separately and then added in an equally weighted and an unequally weighted summing amplifier. The position in each direction is obtained by dividing the output of the unequally weighted summer by that of the equally weighted summer. At 0.94 keV, the accuracy of the position sensing is 190 microns. At the same energy, the energy resolution is approximately 65% (FWHM). The proportional counter system is currently being incorporated into a sounding rocket payload having metal mirror optics, which is being constructed by the X-ray astronomy group at the California Institute of Technology.

Long, K. S.↗

NASA NTRS1978

The application of a drift multiwire proportional counter to the imaging of low energy X-rays

A 75 mm x 75 mm multiwire proportional counter (MWPC) with a 1 micron polypropylene window has been built to map low energy X-rays. The MWPC is constructed with a large drift region which allows us to use the center-of-gravity technique to improve the counter's efficiency and position resolution. Using 330 torr of propane as the gas fill and an anode plane composed of 20 micron diameter Au-plated tungsten wire spaced 1 mm apart, a position resolution of better than 240 microns (FWHM) in two orthogonal directions at an X-ray energy of 0.94 keV has been achieved.

Ku, W. H.-M.↗