13 research outputs found
Radiation Tolerance of Fully-Depleted P-Channel CCDs Designed for the SNAP Satellite
Thick, fully depleted p-channel charge-coupled devices (CCDs) have been
developed at the Lawrence Berkeley National Laboratory (LBNL). These CCDs have
several advantages over conventional thin, n-channel CCDs, including enhanced
quantum efficiency and reduced fringing at near-infrared wavelengths and
improved radiation tolerance. Here we report results from the irradiation of
CCDs with 12.5 and 55 MeV protons at the LBNL 88-Inch Cyclotron and with 0.1-1
MeV electrons at the LBNL Co60 source. These studies indicate that the LBNL
CCDs perform well after irradiation, even in the parameters in which
significant degradation is observed in other CCDs: charge transfer efficiency,
dark current, and isolated hot pixels. Modeling the radiation exposure over a
six-year mission lifetime with no annealing, we expect an increase in dark
current of 20 e/pixel/hr, and a degradation of charge transfer efficiency in
the parallel direction of 3e-6 and 1e-6 in the serial direction. The dark
current is observed to improve with an annealing cycle, while the parallel CTE
is relatively unaffected and the serial CTE is somewhat degraded. As expected,
the radiation tolerance of the p-channel LBNL CCDs is significantly improved
over the conventional n-channel CCDs that are currently employed in space-based
telescopes such as the Hubble Space Telescope.Comment: 11 pages, 10 figures, submitted to IEEE Transaction
Performance results of the GALEX cross delay line detectors
We describe the performance results for the Galaxy Evolution Explorer (GALEX) far ultraviolet (FUV) and near ultraviolet (NUV) detectors. The detectors were delivered to JPL/Caltech starting in the fall of 2000 and have undergone approximately 1000 hours of pre-flight system-level testing to date. The GALEX detectors are sealed tube micro-channel plate (MCP) delay line readout detectors. They have a 65 mm diameter active area, which will be the largest format on orbit. The FUV detector has a spectral bandpass from 115 - 180 nm and the NUV detector has a bandpass from 165 - 300 nm. We report here on the performance of the detectors before and after integration into the instrument. Characteristics measured include the background count rate and distribution, gain vs. applied high voltage, spatial resolution and linearity, flat fields, and quantum efficiency
Keck Planet Finder: design updates
The Keck Planet Finder (KPF) is a fiber-fed, high-resolution, high-stability spectrometer in development at the UC Berkeley Space Sciences Laboratory for the W.M. Keck Observatory. KPF is designed to characterize exoplanets via Doppler spectroscopy with a goal of a single measurement precision of 0.3 m s-1 or better, however its resolution and stability will enable a wide variety of astrophysical pursuits. Here we provide post-preliminary design review design updates for several subsystems, including: the main spectrometer, the fabrication of the Zerodur optical bench; the data reduction pipeline; fiber agitator; fiber cable design; fiber scrambler; VPH testing results and the exposure meter
Keck Planet Finder: design updates
The Keck Planet Finder (KPF) is a fiber-fed, high-resolution, high-stability spectrometer in development at the UC Berkeley Space Sciences Laboratory for the W.M. Keck Observatory. KPF is designed to characterize exoplanets via Doppler spectroscopy with a goal of a single measurement precision of 0.3 m s-1 or better, however its resolution and stability will enable a wide variety of astrophysical pursuits. Here we provide post-preliminary design review design updates for several subsystems, including: the main spectrometer, the fabrication of the Zerodur optical bench; the data reduction pipeline; fiber agitator; fiber cable design; fiber scrambler; VPH testing results and the exposure meter
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The Robotic Multi-Object Focal Plane System of the Dark Energy Spectroscopic Instrument (DESI)
A system of 5,020 robotic fiber positioners was installed in 2019 on the
Mayall Telescope, at Kitt Peak National Observatory. The robots automatically
re-target their optical fibers every 10 - 20 minutes, each to a precision of
several microns, with a reconfiguration time less than 2 minutes. Over the next
five years, they will enable the newly-constructed Dark Energy Spectroscopic
Instrument (DESI) to measure the spectra of 35 million galaxies and quasars.
DESI will produce the largest 3D map of the universe to date and measure the
expansion history of the cosmos. In addition to the 5,020 robotic positioners
and optical fibers, DESI's Focal Plane System includes 6 guide cameras, 4
wavefront cameras, 123 fiducial point sources, and a metrology camera mounted
at the primary mirror. The system also includes associated structural, thermal,
and electrical systems. In all, it contains over 675,000 individual parts. We
discuss the design, construction, quality control, and integration of all these
components. We include a summary of the key requirements, the review and
acceptance process, on-sky validations of requirements, and lessons learned for
future multi-object, fiber-fed spectrographs
The Robotic Multi-Object Focal Plane System of the Dark Energy Spectroscopic Instrument (DESI)
A system of 5,020 robotic fiber positioners was installed in 2019 on the Mayall Telescope, at Kitt Peak National Observatory. The robots automatically re-target their optical fibers every 10 - 20 minutes, each to a precision of several microns, with a reconfiguration time less than 2 minutes. Over the next five years, they will enable the newly-constructed Dark Energy Spectroscopic Instrument (DESI) to measure the spectra of 35 million galaxies and quasars. DESI will produce the largest 3D map of the universe to date and measure the expansion history of the cosmos. In addition to the 5,020 robotic positioners and optical fibers, DESI's Focal Plane System includes 6 guide cameras, 4 wavefront cameras, 123 fiducial point sources, and a metrology camera mounted at the primary mirror. The system also includes associated structural, thermal, and electrical systems. In all, it contains over 675,000 individual parts. We discuss the design, construction, quality control, and integration of all these components. We include a summary of the key requirements, the review and acceptance process, on-sky validations of requirements, and lessons learned for future multi-object, fiber-fed spectrographs