972 research outputs found
Battery Earth: using the subsurface at Boulby underground laboratory to investigate energy storage technologies
Renewable energy provides a low-carbon alternative to power generation in the UK. However, the resultant supply varies on daily, weekly and seasonal cycles, such that for green energies to be fully exploited new grid-scale energy storage systems must be implemented. Two pilot facilities in Germany and the United States have demonstrated the potential of the Earth as a battery to store compressed air, using off-peak surplus energy. Natural accumulations of salt (halite deposits) in the UK represent a large and untapped natural storage reservoir for compressed air with the ability to provide instantaneous green energy to meet peak demand. To realise the potential of this emerging technology, a detailed knowledge of the relationship between mechanics, chemistry and geological properties is required to optimise cavern design, storage potential and economic feasibility. The variable stresses imposed on the rock matrix by gas storage, combined with the cyclic nature of cavern pressurisation are barriers to deployment that need to be addressed to enable large-scale adoption of schemes. Well-designed field experiments are a lynchpin for advancing research in this area, especially when supported by state-of-the-art characterisation and modelling techniques. The research facility at STFC’s Boulby Underground Laboratory presents the ideal location to tackle these fundamental issues to optimise “Battery Earth”
The Cosmology Large Angular Scale Surveyor
The Cosmology Large Angular Scale Surveyor (CLASS) is a four telescope array
designed to characterize relic primordial gravitational waves from inflation
and the optical depth to reionization through a measurement of the polarized
cosmic microwave background (CMB) on the largest angular scales. The
frequencies of the four CLASS telescopes, one at 38 GHz, two at 93 GHz, and one
dichroic system at 145/217 GHz, are chosen to avoid spectral regions of high
atmospheric emission and span the minimum of the polarized Galactic
foregrounds: synchrotron emission at lower frequencies and dust emission at
higher frequencies. Low-noise transition edge sensor detectors and a rapid
front-end polarization modulator provide a unique combination of high
sensitivity, stability, and control of systematics. The CLASS site, at 5200 m
in the Chilean Atacama desert, allows for daily mapping of up to 70\% of the
sky and enables the characterization of CMB polarization at the largest angular
scales. Using this combination of a broad frequency range, large sky coverage,
control over systematics, and high sensitivity, CLASS will observe the
reionization and recombination peaks of the CMB E- and B-mode power spectra.
CLASS will make a cosmic variance limited measurement of the optical depth to
reionization and will measure or place upper limits on the tensor-to-scalar
ratio, , down to a level of 0.01 (95\% C.L.)
CLASS Observations of Atmospheric Cloud Polarization at Millimeter Wavelengths
The dynamic atmosphere imposes challenges to ground-based cosmic microwave
background observation, especially for measurements on large angular scales.
The hydrometeors in the atmosphere, mostly in the form of clouds, scatter the
ambient thermal radiation and are known to be the main linearly polarized
source in the atmosphere. This scattering-induced polarization is significantly
enhanced for ice clouds due to the alignment of ice crystals under gravity,
which are also the most common clouds seen at the millimeter-astronomy sites at
high altitudes. This work presents a multifrequency study of cloud polarization
observed by the Cosmology Large Angular Scale Surveyor (CLASS) experiment on
Cerro Toco in the Atacama Desert of northern Chile, from 2016 to 2022, at the
frequency bands centered around 40, 90, 150, and 220 GHz. Using a
machine-learning-assisted cloud classifier, we made connections between the
transient polarized emission found in all four frequencies with the clouds
imaged by monitoring cameras at the observing site. The polarization angles of
the cloud events are found to be mostly from the local meridian,
which is consistent with the presence of horizontally aligned ice crystals. The
90 and 150 GHz polarization data are consistent with a power law with a
spectral index of , while an excess/deficit of polarization
amplitude is found at 40/220 GHz compared with a Rayleigh scattering spectrum.
These results are consistent with Rayleigh-scattering-dominated cloud
polarization, with possible effects from supercooled water absorption and/or
Mie scattering from a population of large cloud particles that contribute to
the 220 GHz polarization.Comment: 16 pages, 14 figures, submitted to Ap
The Cosmology Large Angular Scale Surveyor
The Cosmology Large Angular Scale Surveyor (CLASS) is a four telescope array designed to characterize relic primordial gravitational waves from inflation and the optical depth to reionization through a measurement of the polarized cosmic microwave background (CMB) on the largest angular scales. The frequencies of the four CLASS telescopes, one at 38 GHz, two at 93 GHz, and one dichroic system at 145217 GHz, are chosen to avoid spectral regions of high atmospheric emission and span the minimum of the polarized Galactic foregrounds: synchrotron emission at lower frequencies and dust emission at higher frequencies. Low-noise transition edge sensor detectors and a rapid front-end polarization modulator provide a unique combination of high sensitivity, stability, and control of systematics. The CLASS site, at 5200 m in the Chilean Atacama desert, allows for daily mapping of up to 70% of the sky and enables the characterization of CMB polarization at the largest angular scales. Using this combination of a broad frequency range, large sky coverage, control over systematics, and high sensitivity, CLASS will observe the reionization and recombination peaks of the CMB E- and B-mode power spectra. CLASS will make a cosmic variance limited measurement of the optical depth to reionization and will measure or place upper limits on the tensor-to-scalar ratio, r, down to a level of 0.01 (95% C.L.)
The Cosmology Large Angular Scale Surveyor (CLASS) Telescope Architecture
We describe the instrument architecture of the Johns Hopkins University-led CLASS instrument, a groundbased cosmic microwave background (CMB) polarimeter that will measure the large-scale polarization of the CMB in several frequency bands to search for evidence of inflation
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