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Zombeck, M. V.

Publications and source records attributed to Zombeck, M. V..

16 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

Feasibility study of the use of synchrotron radiation in the calibration of AXAF - Initial reflectivity results

The 1-percent calibration accuracy goal of the Advanced X-ray Astrophysics Facility is being approached by way of an experiment at the National Synchrotron Light Source that will demonstrate the accuracy achievable in reflectance measurements conducted on coated flat mirrors in the 50 eV-12 keV energy range. The coatings will be of commercially produced Au, Ni, and Ir, deposited either by sputtering or by e-beam deposition. Optical constants will be estimated via the reflectance vs. angle-of-incidence method.

Graessle, D. E.↗
NASA NTRS1991

Uniformity and transmission of proportional counter window materials for use with AXAF

The X-ray detection system used to calibrate the Advanced X-ray Astrophysics Facility (AXAF) mirrors will include gas flow and sealed proportional counters. To meet the ultimate 1 percent goal of the calibration project, the transmission and uniformity of the windows must be well known for the soft X-ray wavelengths involved. Various window materials for use with proportional counters are examined for transmission at X-ray wavelengths in the range of 0.1 to 5.9 keV. These include the usual window materials (polypropylene and beryllium), as well as materials only recently employed for detector applications (polyimide and diamond). The transmission uniformity of beryllium at 1.49 keV is examined with a microchannel plate detector, producing a 'shadowgraph' of the window material illuminated with soft X-rays. This technique allows us to investigate nonuniformities on a spatial scale of about .2 mm.

Flanagan, K.↗
NASA NTRS1991

Proportional counter windows for the Bragg Crystal Spectrometer on AXAF

A Bragg Crystal Spectrometer (BCS) using a gas flow proportional counter as its primary detector is among the instruments under development for AXAF. The BCS will employ windows of 1-micron-thick polyimide coated on both sides with 200 A of Al; this window composition, while X-ray transmitting, will leak gas at a lower rate than the polypropylene film-based windows formerly employed. Accounts are given of the results obtained with additional innovative X-ray window materials currently under development, including diamond and Si-enriched Si3N4.

Markert, T. H.↗
NASA NTRS1990

Calibration of the Rosat High Resolution Imager (HRI)

The microchannel plate-based High Resolution Imager (HRI) is one of the focal plane instruments of the Rosat X-ray telescope that was launched on 1 June 1990. The calibration of the HRI is reported and preliminary results from the in-orbit calibration are presented. The quantum efficiency of the detector has been determined as a function of energy, the spatial variation of quantum efficiency, geometric nonlinearities, background, imaging performance, and UV sensitivity. Results of periodic tests of the temporal stability of the instrument are also reported.

Zombeck, M. V.↗
NASA NTRS1986

X-ray testing of the AXAF Technology Mirror Assembly (TMA) mirror

The X-ray performance of the Advanced X-ray Astrophysics Facility TMA in the 0.277-6.4-keV range. The precise figure and smooth surface originally specified (which were expected from the in-process optical and mechanical measurements) are verified. The paper primarily describes the test equipment and methods used and gives examples of the detailed on-axis and off-axis data.

Schwartz, D. A.↗
NASA NTRS1986

Correspondence between AXAF TMA X-ray performance and models based upon mechanical and visible light measurements

The AXAF Technology Mirror Assembly (TMA) was characterized prior to X-ray testing by properties measured mechanically or with visible light; these include alignment offsets, roundness and global-axial-slope errors, axial-figure errors with characteristic lengths greater than about five mm, and surface roughness with scale lengths between about 0.005 and 0.5 mm. The X-ray data of Schwartz et al. (1985) are compared with predictions based upon the mechanical and visible light measurements.

Van Speybroeck, L.↗
NASA NTRS1982

AXAF, a permanent orbiting X-ray observatory - Telescope and instrumentation plans

The Advanced X-ray Astrophysics Facility (AXAF) now under study is to be a long-lived X-ray observatory in space. It is to be launched by the Space Shuttle, maintainable on-orbit, and retrievable for ground re-furbishment. The AXAF is conceived as an X-ray telescope with 6 nested grazing incidence X-ray mirrors (with a maximum aperture of 1.2 m) and interchangeable and replaceable focal plane instruments. The optics will provide 0.5 arcsecond imagery over a several arcminute field and somewhat reduced resolution over 1 degree in the X-ray band from 0.1 to 10 keV (1.2 to 120 A). The characteristics and expected performance of the observatory are described.

Zombeck, M. V.↗
NASA NTRS1982

High resolution X-ray scattering measurements

The results of high angular resolution grazing incidence scattering measurements of highly polished, coated optical flats in the X-ray spectral range of 1.5 to 6.4 keV are reported. The interpretation of these results in terms of surface microtopography is presented and the implications for grazing incidence X-ray imaging are discussed.

Zombeck, M. V.↗
NASA NTRS1982

AXAF, a permanent orbiting X-ray observatory - Telescope and instrumentation plans

The Advanced X-ray Astrophysics Facility (AXAF) now under study is to be a long-lived X-ray observatory in space. It is to be launched by the Space Shuttle, maintainable on-orbit, and retrievable for ground re-furbishment. The AXAF is conceived as an X-ray telescope with 6 nested grazing incidence X-ray mirrors (with a maximum aperture of 1.2 microns) and interchangeable and repleceable focal plane instruments. The optics will provide 0.5 arcsecond imagery over a several arcminute field and somewhat reduced resolution over 1 degree in the X-ray band from 0.1 to 10 keV (1.2 to 120 A). The characteristics and expected performance of the observatory are described.

Zombeck, M. V.↗
NASA NTRS1981

High resolution X-ray scattering measurements for Advanced X-ray Astrophysics Facility /AXAF/

The Advanced X-ray Astrophysics Facility (AXAF) is to be an orbiting X-ray observatory with high resolution imaging capabilities. Specific goals of 0.5 arcsecond resolution, and an encircled energy of 60% within a 1.0 arcsecond diameter circle at 2.5 keV have been established for AXAF. Imaging X-ray optics are primarily limited by scattering of the X-rays from the mirror surfaces. To ensure that the AXAF goals can be met, comprehensive X-ray scattering measurements are being conducted on a large number of flat samples. Sub-arcsecond resolution is achieved in these measurements through use of the MSFC 1000 ft X-ray calibration facility and a high spatial resolution X-ray detector. Flats of various materials, various coatings, and a range of rms surface roughness are being evaluated. Direct evaluation of surface microroughness is also provided by a variety of optical and non-optical means. This paper describes the scattering measurement program, the instrumentation used to obtain the measurements and preliminary results of measurements on several of the sample flats.

Zombeck, M. V.↗
NASA NTRS1981

Preliminary results from a single-photon imaging X-ray charge coupled device /CCD/ camera

A CCD camera is described which has been designed for single-photon X-ray imaging in the 1-10 keV energy range. Preliminary results are presented from the front-side illuminated Fairchild CCD 211, which has been shown to image well at 3 keV. The problem of charge-spreading above 4 keV is discussed by analogy with a similar problem at infrared wavelengths. The total system noise is discussed and compared with values obtained by other CCD users.

Griffiths, R. E.↗
NASA NTRS1978

An atlas of soft X-ray images of the solar corona from Skylab

An atlas is presented which contains daily full-sun photographs of the soft X-ray solar corona taken in two filters with an X-ray telescope on the Apollo telescope mount of Skylab for the period from May 29 to November 27, 1973. The passband of the first filter covers the wavelength regions from 2 to 32 A and 44 to 54 A; the second filter covers the region from 2 to 17 A. Characteristics of the instrument, the wavelength response, and sensitivity are described along with the total data base, of which the atlas represents only 1%. Comparisons are made with observations of the white-light corona, photospheric magnetic field, H-alpha radiation from the chromosphere, and 284-A Fe XV emission from the corona. A complete bibliography of scientific papers that have used the data base and a bibliography of catalogs and atlases containing related data for the same observational period are provided.

Zombeck, M. V.↗
NASA NTRS1978

The XUV spectroheliometer on SMM

The XUV spectroheliometer for the Solar Maximum Mission (SMM) is described. This instrument is a grazing-incidence polychromatic photoelectric spectrometer illuminated by a grazing-incidence telescope mirror. The wavelength range is 20-1336 A, the spectral resolution is between 0.1 and 0.3 A, and the spatial resolution is 4 arcsec. Simultaneous spectroheliograms in twelve spectral lines are obtained by rastering the instrument at variable rates. The scientific objectives and the mission operations concept are also described.

Reeves, E. M.↗
NASA NTRS1977

The S-054 X-ray telescope experiment on Skylab

A description of the S-054 X-ray telescope on Skylab is presented with a discussion of the experimental objectives, observing program, data reduction and analysis. Some results from the Skylab mission are given. The telescope photographically records high-resolution images of the solar corona in several broadband regions of the soft X-ray spectrum. It includes an objective grating used to study the line spectrum. The spatial resolution, sensitivity, dynamic range and time resolution of the instrument were chosen to survey a wide variety of solar phenomena. It embodies improvements in design, fabrication, and calibration techniques which were developed over a ten-year period. The observing program was devised to optimize the use of the instrument and to provide studies on a wide range of time scales. The data analysis program includes morphological studies and quantitative analysis using digitized images. A small sample of the data obtained in the mission is presented to demonstrate the type of information that is available and the kinds of results that can be obtained from it.

Vaiana, G. S.↗
NASA NTRS1975

A comparison of coronal X-ray structures of active regions with magnetic fields computed from photospheric observations

The appearances of several X-ray active regions observed on March 7, 1970 and June 15, 1973 are compared with the corresponding coronal magnetic-field topology. Coronal fields have been computed from measurements of the longitudinal component of the underlying magnetic fields, based on the current-free hypothesis. An overall correspondence between X-ray structures and calculated field lines is established, and the magnetic counterparts of different X-ray features are also examined. A correspondence between enhanced X-ray emission and the location of compact closed field lines is suggested. Representative magnetic-field values calculated under the assumption of current-free fields are given for heights up to 200 sec.

Poletto, G.↗