106,185 research outputs found
Performance of the Imaging Fourier Transform Spectrometer with Photoconductive Detector Arrays: An Application for the AKARI Far-Infrared Instrument
We have developed an imaging Fourier transform spectrometer (FTS) for
space-based far-infrared astronomical observations. The FTS employs a newly
developed photoconductive detector arrays with a capacitive trans-impedance
amplifier, which makes the FTS a completely unique instrument. The FTS was
installed as a function of the far-infrared instrument (FIS: Far-Infrared
Surveyor) on the Japanese astronomical satellite, AKARI, which was launched on
February 21, 2006 (UT) from the Uchinoura Space Center. The FIS-FTS had been
operated for more than one year before liquid helium ran out on August 26,
2007. The FIS-FTS was operated nearly six hundreds times, which corresponds to
more than one hundred hours of astronomical observations and almost the same
amount of time for calibrations. As expected from laboratory measurements, the
FIS-FTS performed well and has produced a large set of astronomical data for
valuable objects. Meanwhile, it becomes clear that the detector transient
effect is a considerable factor for FTSs with photoconductive detectors. In
this paper, the instrumentation of the FIS-FTS and interesting phenomena
related to FTS using photoconductive detectors are described, and future
applications of this kind of FTS system are discussed.Comment: 10 pages, 6 figures, 2 tables, accepted for publication in PASJ AKARI
special issu
Revealing sub-{\mu}m inhomogeneities and {\mu}m-scale texture in H2O ice at Megabar pressures via sound velocity measurements by time-domain Brillouin scattering
Time-domain Brillouin scattering technique, also known as picosecond
ultrasonic interferometry, which provides opportunity to monitor propagation of
nanometers to sub-micrometers length coherent acoustic pulses in the samples of
sub-micrometers to tens of micrometers dimensions, was applied to
depth-profiling of polycrystalline aggregate of ice compressed in a diamond
anvil cell to Megabar pressures. The technique allowed examination of
characteristic dimensions of elastic inhomogeneities and texturing of
polycrystalline ice in the direction normal to the diamond anvil surfaces with
sub-micrometer spatial resolution via time-resolved measurements of variations
in the propagation velocity of the acoustic pulse traveling in the compressed
sample. The achieved two-dimensional imaging of the polycrystalline ice
aggregate in-depth and in one of the lateral directions indicates the
feasibility of three-dimensional imaging and quantitative characterization of
acoustical, optical and acousto-optical properties of transparent
polycrystalline aggregates in diamond anvil cell with tens of nanometers
in-depth resolution and lateral spatial resolution controlled by pump laser
pulses focusing.Comment: 32 pages, 5 figure
The Long Wavelength Array Software Library
The Long Wavelength Array Software Library (LSL) is a Python module that
provides a collection of utilities to analyze and export data collected at the
first station of the Long Wavelength Array, LWA1. Due to the nature of the data
format and large-N (100 inputs) challenges faced by the LWA, currently
available software packages are not suited to process the data. Using tools
provided by LSL, observers can read in the raw LWA1 data, synthesize a filter
bank, and apply incoherent de-dispersion to the data. The extensible nature of
LSL also makes it an ideal tool for building data analysis pipelines and
applying the methods to other low frequency arrays.Comment: accepted to the Journal of Astronomical Instrumentation; 24 pages, 4
figure
- …