Papers by Geoffrey Gaines
SPIE Proceedings, 2008
The Cosmic Hot Interstellar Plasma Spectrometer (CHIPS) observatory launched on 12 January 2003, ... more The Cosmic Hot Interstellar Plasma Spectrometer (CHIPS) observatory launched on 12 January 2003, and was the first and only successful GSFC UNEX (NASA Goddard Spaceflight Center University Explorer class) mission. The UNEX program was conceived by the National Aeronautics and Space Administration (NASA) as a new class of Explorer mission charged with demonstrating that significant science and/or technology experiments can be performed by small satellites with constrained budgets and a limited schedule. The purpose of the observatory was to examine details of the local bubble thermal pressure, spatial distribution and ionization history. The observatory was also used to observe solar spectra, both scattered from the Lunar surface and via a fortuitous 2 nd order scattering path. CHIPS confirmed that spectral features within the 90-260Ǻ band were much dimmer than was predicted by contemporary theories, and operated four years beyond its design lifetime. The observatory was placed in an extended safe-hold mode in April of 2008 for budgetary purposes. The spectrometer consisted of six spectrograph channels which delivered >λ/100 resolution spectra to a single detector. Cost constraints of UNEX led to a design based on a traditional aluminum structure, and an instrument with a large field of view (5º x 26º). All optical and optomechanical systems on the spectrometer performed flawlessly on orbit. We discuss the challenges, difficulties and lessons learned during the design, fabrication and execution stages of the mission.
The Far Ultraviolet Spectroscopic Explorer (FUSE) satellite was launched into orbit on June 24, 1... more The Far Ultraviolet Spectroscopic Explorer (FUSE) satellite was launched into orbit on June 24, 1999. FUSE is now making high resolution (</û< = 20,000- 25,000) observations of solar system, galactic, and extragalactic targets in the far ultraviolet wavelength region (905- 1187 Å). Its high effective area, low background, and planned three year life allow observations of objects which have been too faint for previous high resolution instruments in this wavelength range. In this paper, we describe the on-orbit performance of the FUSE satellite during its first nine months of operation,
We describe the design and development of the CHIPS microchannel plate detector. The Cosmic Hot I... more We describe the design and development of the CHIPS microchannel plate detector. The Cosmic Hot Interstellar Plasma Spectrometer will study the diffuse radiation of the interstellar medium in the extreme ultraviolet band pass of 90Å to 260Å. Astronomical fluxes are expected to be low, so high efficiency in the band pass, good out-of-band rejection, low intrinsic background, and minimal image non-linearities are crucial detector properties. The detector utilizes three 75mm diameter microchannel plates (MCPs) in an abutted Z stack configuration. A NaBr photocathode material deposited on the MCP top surface enhances the quantum detection efficiency. The charge pulses from the MCPs are centroided in two dimensions by a crossed-delayline (XDL) anode. A four panel thin-film filter array is affixed above the MCPs to reduce sensitivity to airglow and scattered radiation, composed of aluminum, polyimide/boron, and zirconium filter panes. The detector is housed in a flight vacuum chamber to p...
The microchannel plate, delay line, detectors developed for the Far Ultraviolet Spectroscopic Exp... more The microchannel plate, delay line, detectors developed for the Far Ultraviolet Spectroscopic Explorer 1 mission to be launched in 1998 are described. The two FUSE detectors have a large format (•184mm x 10mm split into two 88.5 x 10mm segments), with high spatial resolution (<20µm x 50µm FWHM,>9000 x 200 resolution elements) and good linearity (±25µm), high image stability, and counting rates in excess of 4 x 10 4 events sec-1. KBr opaque photocathodes have been employed to provide quantum detection efficiencies of 30-40 % in the 900- 1200Å range. Microchannel plates with 10µm pores and an 80:1 pore length to diameter ratio, with a 95mm x 20mm format have been used in a Z stack configuration to provide the photon amplification (gain • 2 x 10 7). These show narrow pulse height distributions (<35 % FWHM) even with uniform flood illumination, and good background levels (<0.3 event cm-2 sec-1). Flat field images are dominated by the microchannel plate multifiber boundary fi...
The Far Ultraviolet Spectroscopic Explorer (FUSE) satellite was launched into orbit on June 24, 1... more The Far Ultraviolet Spectroscopic Explorer (FUSE) satellite was launched into orbit on June 24, 1999. FUSE is designed to make high resolution (O/'O = 20,000 -25,000) observations of solar system, galactic, and extragalactic targets in the far ultraviolet wavelength region (905 -1187 Å). Its high effective area, low background and planned three year life allow observations of objects which have been too faint for previous high resolution instruments in this wavelength range. The FUSE instrument includes two large format microchannel plate detectors. Each detector system consists of two microchannel plate segments in a Z-stack configuration with double delay line anodes and associated electronics. High detector spatial resolution was required in order to obtain scientific data with high spectral resolving power, and low detector background was necessary in order to observe faint objects. We describe the performance of the FUSE detectors during their first year on orbit, includin...
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 2002
The Cosmic Origins Spectrograph (COS) is a high throughput spectrometer that will be placed on th... more The Cosmic Origins Spectrograph (COS) is a high throughput spectrometer that will be placed on the Hubble Space Telescope (HST) during the last servicing mission in the year 2003. COS will be the most sensitive UV spectrograph ever flown aboard HST and will investigate such fundamental issues as the ionization and baryon content of the intergalactic medium and the origin
We performed in situ angle-resolved photoemission spectroscopy measurements on La 2/3 Sr 1/3 MnO ... more We performed in situ angle-resolved photoemission spectroscopy measurements on La 2/3 Sr 1/3 MnO 3 thin and ultrathin films deposited onto SrTiO 3 substrates in order to determine their electronic band structure. We directly identified, in ultrathin films, an enhancement of the occupation of the out-of-plane Mn 3d e g ͑3z 2r 2 ͒ band at the expense of the in-plane 3d e g ͑x 2y 2 ͒ band. Such a disproportionate change in orbital occupation is interpreted as the origin of the strong depression of the magnetotransport properties at the interface between manganite films and substrates.
Proceedings of …, 1994
Microchannel plate based detectors with cross delay line image readout have been rapidly implemen... more Microchannel plate based detectors with cross delay line image readout have been rapidly implemented for the SUMER and UVCS instruments aboard the Solar Orbiting Heliospheric Observatory (SOHO) mission to be launched in July 1995. In October 1993 a fast track program to ...
The direct absorption spectra of jet-cooled acetone and acetone-dâ have been measured from 51,000... more The direct absorption spectra of jet-cooled acetone and acetone-dâ have been measured from 51,000 to 54,000 cmâ»Â¹. Cooling in a molecular jet allows the resolution of several previously unreported vibronic bands and, consequently, a revised vibrational analysis. Sequence bands of the methyl torsional motion are also resolved; the frequencies of the two torsional vibrations in the Rydberg state are deduced to be 138 and 214 cmâ»Â¹. A single-methyl rotor calculation yields a barrier to the hindered rotation of 1140 cmâ»Â¹.
The direct absorption spectra of jet-cooled acetone and acetone-d/sub 6/ have been measured from ... more The direct absorption spectra of jet-cooled acetone and acetone-d/sub 6/ have been measured from 51,000 to 54,000 cm/sup -1/. Cooling in a molecular jet allows the resolution of several previously unreported vibronic bands and, consequently, a revised vibrational analysis. Sequence bands of the methyl torsional motion are also resolved; the frequencies of the two torsional vibrations in the Rydberg state are deduced to be 138 and 214 cm/sup -1/. A single-methyl rotor calculation yields a barrier to the hindered rotation of 1140 cm/sup -1/.
Journal of Physical Chemistry, 1988
... Phys. 1982, 76, 543. The n,-3s Rydberg State of Acetone: Absorption Spectroscopy of Jet-Coole... more ... Phys. 1982, 76, 543. The n,-3s Rydberg State of Acetone: Absorption Spectroscopy of Jet-Cooled (CH3)2C0 and (CD3)2C0 Geoffrey A. Gaines, D. J. Donaldson, SJ Strickler, and Veronica Vaida* ... Phys. 1971, (5) Vaida, V. Ace. Chem. Res. 1986, 19, 114. ...
Journal of Physical Chemistry, 1988
... The intensities of these overtone modes may also be enhanced via Fermi resonance with the us ... more ... The intensities of these overtone modes may also be enhanced via Fermi resonance with the us mode. This as-signment is supported by the Franck-Condon calculation reported above. ... (2) Donaldson, DJ; Leone, SR J. Chem. Phys. 1986, 85, 817. ...
EUV, X-Ray, and Gamma-Ray Instrumentation for Astronomy, 1990
ABSTRACT Measurements of the EUV quantum detection efficiency (QDE) of opaque RbBr, CsBr, and KBr... more ABSTRACT Measurements of the EUV quantum detection efficiency (QDE) of opaque RbBr, CsBr, and KBr photocathodes are described and investigations of their photoemission characteristics over the 44-1560 A wavelength range are reported. The results show that high QDEs can be obtained in the EUV. Narrow QDE peaks at soft X-ray wavelengths occur at slightly different wavelengths for each of the materials studied. The long-wavelength thresholds vary according to the material band gap. Data on the photoemission from the photocathode layer on the microchannel plate interchannel web area are used to determine the number and energy distribution of the emitted photoelelectrons as a function of wavelength.© (1990) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Proceedings of SPIE - The International Society for Optical Engineering
Measurements of the EUV quantum detection efficiency (QDE) of opaque RbBr, CsBr, and KBr photocat... more Measurements of the EUV quantum detection efficiency (QDE) of opaque RbBr, CsBr, and KBr photocathodes are described and investigations of their photoemission characteristics over the 44-1560 A wavelength range are reported. The results show that high QDEs can be obtained in the EUV. Narrow QDE peaks at soft X-ray wavelengths occur at slightly different wavelengths for each of the materials studied. The long-wavelength thresholds vary according to the material band gap. Data on the photoemission from the photocathode layer on the microchannel plate interchannel web area are used to determine the number and energy distribution of the emitted photoelelectrons as a function of wavelength.
UV/EUV and Visible Space Instrumentation for Astronomy II, 2003
Page 1. Performance of the Cosmic Hot Interstellar Plasma Spectrometer Martin M. Sirk , Geoffrey ... more Page 1. Performance of the Cosmic Hot Interstellar Plasma Spectrometer Martin M. Sirk , Geoffrey Gaines , Ellen R. Taylor , Michael Sholl , William Marchant , Richelieu Hemphill , Randy A. Kimble , Timothy Sasseen , Mario Marckwordt , and William Donakowski ...
UV/EUV and Visible Space Instrumentation for Astronomy II, 2003
We describe the design and development of the CHIPS microchannel plate detector. The Cosmic Hot I... more We describe the design and development of the CHIPS microchannel plate detector. The Cosmic Hot Interstellar Plasma Spectrometer will study the diffuse radiation of the interstellar medium in the extreme ultraviolet band pass of 90Å to 260Å. Astronomical fluxes are expected to be low, so high efficiency in the band pass, good out-of-band rejection, low intrinsic background, and minimal image non-linearities are crucial detector properties. The detector utilizes three 75mm diameter microchannel plates (MCPs) in an abutted Z stack configuration. A NaBr photocathode material deposited on the MCP top surface enhances the quantum detection efficiency. The charge pulses from the MCPs are centroided in two dimensions by a crossed-delayline (XDL) anode. A four panel thin-film filter array is affixed above the MCPs to reduce sensitivity to airglow and scattered radiation, composed of aluminum, polyimide/boron, and zirconium filter panes. The detector is housed in a flight vacuum chamber to preserve the hygroscopic photocathode, the pressure sensitive thin-film filters, and to permit application of high voltage during ground test.
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Papers by Geoffrey Gaines