Achievement of 0.005 % combined transfer uncertainties in the NIST detector calibration facility

Improvements in a lamp-monochromator-based facility at the National Institute of Standards and Technology (NIST), the Visible near-infrared Spectral Comparator Facility (VisSCF) which is used to calibrate optical detectors for spectral radiant power responsivity from 300 nm to 1100 nm, are described. These changes include extending the VisSCF operational range down to 300 nm from 350 nm, thereby fully covering the ultraviolet-A (UVA) spectral region and partially covering the UVB range. These improvements have lowered the magnitudes of most of the components in the uncertainty budget and have led to combined 0.005 % transfer (k=1) uncertainties in the spectral power responsivity calibrations over most of the spectral range. Redevelopment of the uncertainty budget results in total expanded uncertainties of spectral responsivities of less than 0.1 % (k=2) over the spectral range from 380 nm to 980 nm, with the greatest uncertainty term coming from the calibrations of the transfer standards.

VALIDATION OF THE GEIGER-MULLER COUNTER MODEL OF BDMG-04-02 USING THE MONTE-CARLO TECHNIQUE

The model of the Geiger-Muller counter as the internal part of BDMG-04-02 detection unit in the calibration fa-cility UPGD-2 was developedin MCNP6.2. The different methods are used for the determination of the Geiger-Muller counter response. The F1 and F8 tally applicability is briefly described. BDMG-04-02 model was validated by comparative analysis of the calculated results and experimental values of the counter responses that obtained on the UPGD-2 calibration facility. Additionally, the absolute, geometric and intrinsic registration efficiency of BDMG-04-02 was determined. The paper has been emphasized the disadvantages of using the method of direct counting of the electrons on the surface of the Geiger-Muller counter (F1).

Radiometric Performance Evaluation of FY-4A/AGRI Based on Aqua/MODIS

Fengyun-4A (FY-4A) is the first satellite of the Chinese second-generation geostationary orbit meteorological satellites (FY-4). The Advanced Geostationary Radiation Imager (AGRI), onboard FY-4A does not load with high-precision calibration facility in visible and near infrared (VNIR) channel. As a consequence, it is necessary to comprehensively evaluate its radiometric performance and quantitatively describe the attenuation while using its VNIR data. In this paper, the radiometric performance at VNIR channels of FY-4A/AGRI is evaluated based on Aqua/MODIS data using the deep convective cloud (DCC) target. In order to reduce the influence of view angle and spectral response difference, the bi-directional reflectance distribution function (BRDF) correction and spectral matching have been performed. The evaluation result shows the radiometric performance of FY-4A/AGRI: (1) is less stable and with obvious fluctuations; (2) has a lower radiation level because of 24.99% lower compared with Aqua/MODIS; 3) has a high attenuation with 9.11% total attenuation over 2 years and 4.0% average annual attenuation rate. After the evaluation, relative radiometric normalization between AGRI and MODIS in VNIR channel is performed and the procedure is proved effective. This paper proposed a more reliable reference for the quantitative applications of FY-4A data.

Hyperspectral-reflectance dataset of dry, wet and submerged marine litter

This paper describes a dataset consisting of 47 hyperspectral-reflectance measurements of plastic litter samples. The plastic litter samples include virgin and real samples from the Port of Antwerp. They were measured in dry conditions in the Flemish Institute for Technological Research (VITO) calibration facility, and a selection of the samples were also measured in wet conditions and submerged in a water tank at Flanders Hydraulics. The construction on top of the tank allowed us to submerge the plastics and keep sediments in suspension. The spectral measurements were performed using an Analytical Spectral Devices (ASD) FieldSpec 4 and a Spectral Evolution (SEV) spectrometer. The datasets are available on the 4TU.ResearchData open-access repository (ASD dataset: https://doi.org/10.4121/12896312.v2, Knaeps et al., 2020; SEV dataset: https://doi.org/10.4121/uuid:9ee3be54-9132-415a-aaf2-c7fbf32d2199; Garaba et al., 2020).

LaBr3(Ce) Crystal Spectrometric Detection Unit for Studying the Field of Capture Gamma Radiation with Energies from 4 MeV to 9 MeV

The paper describes some features of the LaBr3(Ce) crystal in comparison with the NaI(Tl) crystal. The instrumental spectra obtained by the spectrometric detection unit with a LaBr3(Ce) crystal in the fields of high-energy capture gamma radiation at neutron calibration facility AT-140 in the energy range from 4 MeV to 9 MeV are presented. It was shown that the energy calibration of LaBr3(Ce) – based spectrometers can be performed in the range from 30 keV to 10 MeV using high-energy capture gamma radiation at AT-140 and the lanthanum intrinsic radioactivity line without resorting to OSGI sources.