23,449 research outputs found
Microwave apparatus for gravitational waves observation
In this report the theoretical and experimental activities for the
development of superconducting microwave cavities for the detection of
gravitational waves are presented.Comment: 42 pages, 28 figure
Pulsed response of a traveling-wave tube
The consequence of frequency-domain multiple access (FDMA) channelization in a satellite communications system is that the ground- and space-based components are often required to operate at reduced output power to prevent the generation of distortions. However, the components of a time-division multiple access (TDMA) satellite system, such as a traveling-wave tube (TWT), can operate at the highest output power because the channelization technique is relatively insensitive to the distortions resulting from saturated operation. A Hughes 30-GHz TWT was tested to determine the suitability of such a device in a TDMA system. Testing was focused on the ability of the TWT to rise up to full power at the leading edge of TDMA bursts, which were simulated by a pulse train. A Wavetek model 8502A peak power meter was used to display and measure the pulsed signal waveform. Measurements of the TWT output signal rise time indicate that the TWT lengthened the rise time by 10 to 20 nsec. Imposing a modulator turn-on time that precedes the data burst by the TWT rise time is a logical approach to coordinating the traveling-wave tube amplifier and modulator specifications
Precision of cavity-enhanced optical rotation measurements
The signal to noise ratio in atomic magnetometry is fundamentally limited by the optical depth of the atomic ensemble. During the last decade, different technics for optical depth enhancement has been developed by several groups, some of them involving the implementation of an optical cavity. This thesis evaluates the performance of such an implementation by the polarization read out noise analysis of an optical cavity with similar characteristics as the already implemented by other groups. We obtained an estimated value for the signal to noise ratio enhancement with a cavity of 814 Finesse, and we studied the behaviour of the different sources of polarization noise in this system
Planetary film reconnaissance system
Design, fabrication, assembly of planetary film reconnaissance syste
Gemini Planet Imager Observational Calibrations II: Detector Performance and Calibration
The Gemini Planet Imager is a newly commissioned facility instrument designed
to measure the near-infrared spectra of young extrasolar planets in the solar
neighborhood and obtain imaging polarimetry of circumstellar disks. GPI's
science instrument is an integral field spectrograph that utilizes a HAWAII-2RG
detector with a SIDECAR ASIC readout system. This paper describes the detector
characterization and calibrations performed by the GPI Data Reduction Pipeline
to compensate for effects including bad/hot/cold pixels, persistence,
non-linearity, vibration induced microphonics and correlated read noise.Comment: 11 pages, 6 figures. Proceedings of the SPIE, 9147-28
The Calibration and Data Products of the Galaxy Evolution Explorer
We describe the calibration status and data products pertaining to the GR2
and GR3 data releases of the Galaxy Evolution Explorer (GALEX). These releases
have identical pipeline calibrations that are significantly improved over the
GR1 data release. GALEX continues to survey the sky in the Far Ultraviolet
(FUV, ~154 nm) and Near Ultraviolet (NUV, ~232 nm) bands, providing
simultaneous imaging with a pair of photon counting, microchannel plate, delay
line readout detectors. These 1.25 degree field-of-view detectors are
well-suited to ultraviolet observations because of their excellent red
rejection and negligible background. A dithered mode of observing and photon
list output pose complex requirements on the data processing pipeline,
entangling detector calibrations and aspect reconstruction algorithms. Recent
improvements have achieved photometric repeatability of 0.05 and 0.03 mAB in
the FUV and NUV, respectively. We have detected a long term drift of order 1%
FUV and 6% NUV over the mission. Astrometric precision is of order 0.5" RMS in
both bands. In this paper we provide the GALEX user with a broad overview of
the calibration issues likely to be confronted in the current release.
Improvements are likely as the GALEX mission continues into an extended phase
with a healthy instrument, no consumables, and increased opportunities for
guest investigations.Comment: Accepted to the ApJS (a special GALEX issue
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