FORMATION AND MONITORING OF SECONDARY X-RAY RADIATION UNDER PRODUCT PROCESSING WITH ELECTRON BEAM

When conducting an industrial radiation processes at an electron accelerator, a part of the beam energy is trans-formed into bremsstrahlung radiation. In such a way, the mixed e,X-radiation is formed in the area behind an irra-diated object. The intensity of the electron and photon components in the radiation is determined by the energy and power of the primary electron beam, as well as by the parameters of the object and devices located behind it. In paper, the characteristics of the e,X-radiation accompanying the product processing by a scanning electron beam with energy 8…12 MeV at a LU-10 Linac of NSC KIPT are studied. The conditions for obtaining a source of sec-ondary X-rays in the state of electronic equilibrium, as well as its monitoring using an extended free-air ionization chamber are explored. Such an extra-source of radiation can be used for carrying out various non-commercial pro-grams like radiation tests, sanitization of archival materials and cultural heritage objects, etc.

Assessing the WRF-Solar model performance using satellite-derived irradiance from the National Solar Radiation Database

WRF-Solar is a numerical weather prediction (NWP) model specifically designed to meet the increasing demand for accurate solar irradiance forecasting. The model provides flexibility in the representation of the aerosol-cloud-radiation processes. This flexibility can be argued to make more difficult to improve the model’s performance due to the necessity of inspecting different configurations. To alleviate this, WRF-Solar has a reference configuration to use it as a benchmark in sensitivity experiments. However, the scarcity of high-quality ground observations is a handicap to accurately quantify the model performance. An alternative to ground observations are satellite irradiance retrievals. Herein we analyze the adequacy of the National Solar Radiation Database (NSRDB) to validate the WRF-Solar performance using high-quality global horizontal irradiance (GHI) observations across the CONUS. Based on the sufficient performance of NSRDB, we further analyze the WRF-Solar forecast errors across the CONUS, the growth of the forecasting errors as a function of the lead time, sensitivities to the grid spacing, and to the representation of the radiative effects of unresolved clouds. Our results based on WRF-Solar forecasts spanning the year of 2018 reveal a 7% median degradation of the mean absolute error (MAE) from the first to the second daytime period. Reducing the grid spacing from 9 km to 3 km leads to a 4% improvement in the MAE, whereas activating the radiative effects of unresolved clouds is desirable over most of the CONUS even at 3 km of grid spacing. A systematic overestimation of the GHI is found. These results illustrate the potential of GHI retrievals to contribute increasing the WRF-Solar performance.

Morphological and genetic data suggest a complex pattern of inter-island colonisation and differentiation for mining bees (Hymenoptera: Anthophila: Andrena) on the Macaronesian Islands

Oceanic islands have long been considered engines of differentiation and speciation for terrestrial organisms. Here we investigated colonisation and radiation processes in the Madeira Archipelago and the Canary Islands of the Andrena wollastoni group of bees (subgenus Micrandrena), which comprises six endemic species and five endemic subspecies on the islands. Mitochondrial COI sequences support the monophyly of the four species of the Canary Islands and the two species of the Madeira Archipelago and suggest a relatively young age for all taxa. The data do not support a simple stepping-stone model (eastern-western colonisation from the mainland, with splitting into new taxa), but suggest Andrena gomerensis (extant on La Gomera and La Palma) or its ancestor as the basal lineage from which all other taxa evolved. Andrena lineolata (Tene-rife) or its putative ancestor (A. gomerensis) is sister to A. dourada (Porto Santo), A. catula (Gran Canaria), and A. acuta (also Tenerife). Andrena dourada (Porto Santo) and A. wollastoni (Madeira Island) are sister species. Morphologically and morphometrically defined subspecies were not distinguishable with COI DNA sequences. Colonisation likely led from the Canary Islands to the Madeira Archipelago and not from the mainland directly to the latter.

Numerical simulation of measurements in radiation technologies

Radiation plays a very important role in the life of humans. Measurements in radiation technologies and radiation processes are very important. Usually measurements in radiation technologies are made with dosimeters of various types: solid state dosimeters, liquid dosimeters and gaseous dosimeters. Dose measurements are based on different principles: temperature increase, collection of electric charge, development of gases, accumulation of free radicals, trapping of electron in the matrix, color change, change of solution conductivity, radiation chemical oxidation, radiation chemical reduction. To measure absorbed doses the dosimetry system should be used which consists of dosimeters, measurement instrumentation, the calibration curve, reference standards and procedure for the system’s use. Computer processing power has increased rapidly and significantly over the past decades. Modern computers with proper software and mathematical methods allow to simulate very complicated processes, for example passage of ionizing radiation through the matter. Article shows that GEANT4 can be used for numerical simulations to determine the absorbed doses, dose rates, and other values inside irradiated objects under radiation. The relative uncertainty is up to 11.8%. Simulation of radiation processing of complex objects can be performed with good accuracy. In order to use numerical simulations to measure radiation, metrological support should be developed.

Acridin-9(10H)-one based thermally activated delayed fluorescence material: simultaneous optimization of RISC and radiation processes to boost luminescence efficiency

The high radiation and RISC rate constants were achieved simultaneously for a TADF emitter with acridin-9(10H)-one as acceptor due to high molecular rigidity and multichannel RISC processes, OLED with this TADF emitter exhibits a high EQE of 30.6%.

Study of the process $$e^+e^- \rightarrow \eta \pi ^0\gamma $$ in the energy range $$\sqrt{s} = {1.05-2.00}$$ GeV with the SND detector

The process $$e^+e^-\rightarrow \eta \pi ^0\gamma $$ e + e - → η π 0 γ is studied in the center-of-mass energy range 1.05–2.00 GeV using data with an integrated luminosity of 94.5 $$\hbox {pb}^{-1}$$ pb - 1 collected by the SND detector at the VEPP-2000 $$e^{+}e^{-}$$ e + e - collider. The $$e^+e^-\rightarrow \eta \pi ^0\gamma $$ e + e - → η π 0 γ cross section is measured for the first time. It is shown that the dominant mechanism of this reaction is the transition through the $$\omega \eta $$ ω η intermediate state. The measured cross section of the subprocess $$e^+e^-\rightarrow \omega \eta \rightarrow \eta \pi ^0\gamma $$ e + e - → ω η → η π 0 γ is consistent with previous measurements in the $$e^+e^-\rightarrow \pi ^+\pi ^-\pi ^0\eta $$ e + e - → π + π - π 0 η mode. It is found, with a significance of $$5.6\sigma $$ 5.6 σ , that the process $$e^+e^-\rightarrow \eta \pi ^0\gamma $$ e + e - → η π 0 γ is not completely described by hadronic vector-pseudoscalar intermediate states. The cross section of this missing contribution, which can originate from radiation processes, e. g. $$e^+e^-\rightarrow a_{0}(1450)\gamma $$ e + e - → a 0 ( 1450 ) γ , is measured. It is found to be 15–20 pb in the wide energy range from 1.3 to 1.9 GeV.

Cygnus survey with the Giant Metrewave Radio Telescope at 325 and 610 MHz: the catalog

Context. Observations at the radio continuum band below the gigahertz band are key when the nature and properties of nonthermal sources are investigated because their radio radiation is strongest at these frequencies. The low radio frequency range is therefore the best to spot possible counterparts to very high-energy (VHE) sources: relativistic particles of the same population are likely to be involved in radio and high-energy radiation processes. Some of these counterparts to VHE sources can be stellar sources. Aims. The Cygnus region in the northern sky is one of the richest in this type of sources that are potential counterparts to VHE sources. We surveyed the central ∼15 sq deg of the Cygnus constellation at the 325 and 610 MHz bands with angular resolutions and sensitivities of 10″ and 6″, and 0.5 and 0.2 mJy beam−1, respectively. Methods. The data were collected during 172 h in 2013–2017, using the Giant Metrewave Radio Telescope with 32 MHz bandwidth, and were calibrated using the SPAM routines. The source extraction was carried out with the PyBDSF tool, followed by verification through visual inspection of every putative catalog candidate source in order to determine its reliability. Results. In this first paper we present the catalog of sources, consisting of 1048 sources at 325 MHz and 2796 sources at 610 MHz. By cross-matching the sources from both frequencies with the objects of the SIMBAD database, we found possible counterparts for 143 of them. Most of the sources from the 325-MHz catalog (993) were detected at the 610 MHz band, and their spectral index α was computed adopting S(ν) ∝ να. The maximum of the spectral index distribution is at α = −1, which is characteristic of nonthermal emitters and might indicate an extragalactic population.