The magnetized steel and scintillator calorimeters of the MINOS experiment Allison, W.W.M.; Andreopoulos, C.; Ayres, D.S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2008, Letnik:
596, Številka:
2
Journal Article
Recenzirano
Odprti dostop
The Main Injector Neutrino Oscillation Search (MINOS) experiment uses an accelerator-produced neutrino beam to perform precision measurements of the neutrino oscillation parameters in the ...“atmospheric neutrino” sector associated with muon neutrino disappearance. This long-baseline experiment measures neutrino interactions in Fermilab's NuMI neutrino beam with a near detector at Fermilab and again 735
km downstream with a far detector in the Soudan Underground Laboratory in northern Minnesota. The two detectors are magnetized steel-scintillator tracking calorimeters. They are designed to be as similar as possible in order to ensure that differences in detector response have minimal impact on the comparisons of event rates, energy spectra and topologies that are essential to MINOS measurements of oscillation parameters. The design, construction, calibration and performance of the far and near detectors are described in this paper.
The SeaSWIR dataset Knaeps, Els; Doxaran, David; Dogliotti, Ana ...
Earth system science data,
08/2018, Letnik:
10, Številka:
3
Journal Article
Recenzirano
Odprti dostop
The SeaSWIR dataset consists of 137 ASD (Analytical Spectral Devices, Inc.)
marine reflectances, 137 total suspended matter (TSM) measurements and 97
turbidity measurements gathered at three turbid ...estuarine sites (Gironde, La
Plata, Scheldt). The dataset is valuable because of the high-quality
measurements of the marine reflectance in the Short Wave InfraRed I region
(SWIR-I: 1000–1200 nm) and SWIR-II (1200–1300 nm) and
because of the wide range of TSM concentrations from 48 up to
1400 mg L−1. The ASD measurements were gathered using a detailed
measurement protocol and were subjected to a strict quality control. The
SeaSWIR marine reflectance is characterized by low reflectance at short
wavelengths (<450 nm), peak reflectance values between 600 and
720 nm and significant contributions in the near-infrared (NIR) and
SWIR-I parts of the spectrum. Comparison of the ASD water reflectance with
simultaneously acquired reflectance from a three-radiometer system revealed a
correlation of 0.98 for short wavelengths (412, 490 and 555 nm) and
0.93 for long wavelengths (686, 780 and 865 nm). The relationship
between TSM and turbidity (for all sites) is linear, with a correlation
coefficient of 0.96. The SeaSWIR dataset has been made publicly available
(https://doi.org/10.1594/PANGAEA.886287).
Theory and seaborne measurements are presented for the near infrared (NIR: 700-900 nm) water-leaving reflectance in turbid waters. According to theory, the shape of the NIR spectrum is determined ...largely by pure water absorption and is thus almost invariant. A "similarity" NIR reflectance spectrum is defined by normalization at 780 nm. This spectrum is calculated from seaborne reflectance measurements and is compared with that derived from laboratory water absorption measurements. Factors influencing the shape of the similarity spectrum are analyzed theoretically and by radiative transfer simulations. These simulations show that the similarity spectrum is valid for waters ranging from moderately turbid (e.g., water-leaving reflectance at 780 nm of order 10-4or total suspended matter concentration of order$0.3 g m^{-3}$) to extremely turbid (e.g., reflectance at 780 nm of order 10-1or total suspended matter of order$200 g m^{-3}$). Measurement uncertainties are analyzed, and the air-sea interface correction is shown to be critical for low reflectances. Applications of the NIR similarity spectrum to atmospheric correction of ocean color data and to the quality control of seaborne, airborne, and spaceborne reflectance measurements in turbid waters are outlined.
Results are presented of a three-dimensional model study of the tidally-averaged salinity field in the Rhine-Meuse plume. In conditions of low mixing (no wind, neap tide) freshwater emerges from the ...river as a jet, turns right under the influence of Coriolis force and attaches to the coast as a buoyancy current. Surface residual currents are essentially geostrophic. Within the plume the surface layer is strongly stratified and overlies a bottom mixed layer.
Results are strongly sensitive to the parameterization of vertical mixing: models ranging from constant diffusion coefficients through simple algebraic Richardson number dependent formulations to turbulence closure with evolution equations for turbulent kinetic energy and length scale were tested. Turbulence closure with a single evolution equation for turbulent kinetic energy and an algebraic length scale formulation was found to provide a suitable balance between physical realism (assessed by theoretical considerations and the practical ability to represent a well-mixed bottom boundary layer and stratified surface layer) and computational efficiency. Simpler models, which vary diffusion coefficients as function of Richardson number, may produce similar results, though require more careful calibration. Constant diffusion coefficients are clearly inadequate for the application considered. Even the preferred “
k” model requires some calibration as a “background” or “ambient” mixing coefficient had to be introduced to avoid unrealistically strong stratification.
The tidally-averaged salinity field was found to be qualitatively similar at neap and spring tide, though cross-shore penetration of the outflow jet was reduced, bottom-mixed layer thickness increased and overall stratification reduced at springs. In contrast, the salinity field was found to be strongly dependent on wind strength and direction, both through wind-induced surface mixing and advection by wind-driven surface currents.
Spontaneous light emission from fibers in MINOS Avvakumov, S.; Barrett, W.L.; Belias, T. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
06/2005, Letnik:
545, Številka:
1
Journal Article
Recenzirano
We report on the observation and measurements of unexpected background rates in the MINOS Far Detector. The noise level at the Far Detector is significantly greater than that expected from natural ...radioactivity and intrinsic photomultiplier dark current. We have conducted a series of additional tests which demonstrate that the excess rate is caused by spontaneous light emission in the wavelength-shifting fibers, which are used to read out signals from scintillator strips. This noise due to fibers exhibits an exponential fall off with time with a decay time constant of the order of 100 days.
A 3D hydrodynamical model has been set up to describe the distribution and variability of the salinity in Belgian coastal waters. Particular attention was paid to determining the relative impact of ...the Scheldt and Rhine/Meuse freshwater plumes and testing the hypothesis that the salinity of Belgian waters is primarily a mix between salty offshore water and freshwater from the Scheldt Estuary. Attention was also paid to determining whether the Seine has significant impact on the Belgian zone.
The 3D hydrodynamical model, based on COHERENS, has been applied to the Channel and the Southern Bight of the North Sea using a 5′ (longitude) by 2.5′ (latitude) grid. The model has been run for the years 1991–2002. Real river runoffs have been taken into account for the main rivers within the domain: the Scheldt, the Rhine/Meuse, the Seine and the Thames.
Model tracers were used to characterise the signature of water masses in terms of Atlantic and riverine waters. Results indicate that the salinity of Belgian waters is dominated by inflow of the Channel water mass which mixes with freshwater originating mainly from the Rhine/Meuse with a much smaller contribution from the Scheldt Estuary. This conclusion is further supported by simulation results obtained when each river discharge is separately set to zero. Thus, the ‘generally accepted’ hypothesis of a ‘continental coastal river’ with fresher coastal water flowing north-eastward up the French-Belgian-Dutch coast and picking up freshwater from successive outflows seems inappropriate for Belgian waters where horizontal dispersion of Rhine/Meuse water in the opposite direction is significant.
Ocean colour applications from medium-resolution polar-orbiting satellite sensors have now matured and evolved into operational services. These applications are enabled by the Sentinel-3 OLCI space ...sensors of the European Earth Observation Copernicus programme and the VIIRS sensors of the US Joint Polar Satellite System programme. Key drivers for the Copernicus ocean colour services are the national obligations of the EU member states to report on the quality of marine, coastal and inland waters for the EU Water Framework Directive and Marine Strategy Framework Directive. Further applications include CO2 sequestration, carbon cycle and climate, fisheries and aquaculture management, near-real-time alerting to harmful algae blooms, environmental monitoring and forecasting, and assessment of sediment transport in coastal waters. Ocean colour data from polar-orbiting satellite platforms, however, suffer from fractional coverage, primarily due to clouds, and inadequate resolution of quickly varying processes. Ocean colour remote sensing from geostationary platforms can provide significant improvements in coverage and sampling frequency and support new applications and services. EUMETSAT's SEVIRI instrument on the geostationary Meteosat Second Generation platforms (MSG) is not designed to meet ocean colour mission requirements, however, it has been demonstrated to provide valuable contribution, particularly in combination with dedicated ocean colour polar observations. This paper describes the ongoing effort to develop operational ocean colour water turbidity and related products and user services from SEVIRI. SEVIRI's multi-temporal capabilities can benefit users requiring improved local-area coverage and frequent diurnal observations. A survey of user requirements and a study of technical capabilities and limitations of the SEVIRI instruments are the basis for this development and are described in this paper. The products will support monitoring of sediment transport, water clarity, and tidal dynamics by providing hourly coverage and long-term time series of the diurnal observations. Further products and services are anticipated from EUMETSAT's FCI instruments on Meteosat Third Generation satellites (MTG), including potential chlorophyll a products.
Three turbulence closure schemes, designed for stratified shallow water flows, are presented. They are based upon κ-ε theory and use respectively two, one or zero transport equations for turbulent ...variables. The models are first tested on the evolution of a wind-driven turbulent layer in a stratified fluid. The results are at least qualitatively in agreement with observational and experimental data. A discussion is given about the existence of self-similar solutions. The models are compared next with the observational data of the Rhine outflow area. The periodic variation in the density structure, forced by wind and tides and which is clearly visible in the data, is predicted by the model. A physical interpretation of the model results is given in the absence of wind forcing. The effects of estuarine circulation, tidal straining and mixing on the development or breakdown of stratification are well represented by the model calculations.
On the linearity of the MINOS light-injection calibration system Adamson, P; Barrett, L; Belias, A ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2004, Letnik:
521, Številka:
2
Journal Article
Recenzirano
The MINOS light-injection calibration system has been fully documented in a previous article (Nucl. Instr. and Meth. A 492 (2002) 353). Upon commissioning in the MINOS detectors, the system was found ...to give a non-linear response to variations in the intensity of injected light. The source of this non-linearity has been traced to a small change in the spectrum of the injected light as a function of the current applied to the original blue LEDs, in combination with a rapidly varying spectral response function of the wavelength-shifting fibre used in the detector. Both aspects of the problem have been addressed successfully by use of LEDs with different spectral characteristics, and the system now has a linear response.
The goal of this paper is to present in situ data for the reflectance and transparency of river plumes and to interpret the observed variability in terms of hydrodynamic processes. The data was ...obtained for river plumes in the Black Sea and in Arctic Ocean regions. Spectral reflectance was measured in the 400- 700nm band by a ship/helicopter-mounted spectroradiometer and was supplemented by shipboard measurements of vertical profiles of the light attenuation coefficient. Remotely-sensed data shows the transition from freshwater to sea water with both sharp boundary fronts and wide mixing zones. Internal fronts and quasi-periodic spatial variability of reflectance were also observed within the river plume. The observations are related to the relevant hydrodynamic processes (fronts, advection and settling of particulate matter, internal waves). A radiance model was developed to match the vertical profile of optical properties to the observed variation of remotely-sensed reflectance.
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