Abstract
We elaborated a technique of pulsed laser ablation in gas mixtures (He-N
2
), maintained under residual pressures of 0.5–5 Torr to deposit silicon (Si)-based nanostructured films on a ...substrate. We show that the deposited films can exhibit strong photoluminescence (PL) emission with the position of peaks depending on the pressure of ambient gas and the ratio of gases in the mixture. Nanostructured films prepared in pure He gas exhibited a strong band in the infrared range (around 760 nm) and a weak band in the green range (550 nm), which were attributed to quantum-confined excitonic states in small Si nanocrystals and radiative transitions via the localized electronic states in silicon suboxide coating, respectively. In contrast, nanostructured films prepared in He-N
2
mixtures exhibited more intense “green-yellow” PL band centered at 580 nm, which was attributed to a radiative recombination in amorphous oxynitride (a-SiN
x
O
y
) coating of Si nanocrystals. We also present a detailed analysis of morphology of nanostructures Si-based films prepared by laser ablation. Finally, we show that the nanocrystals can be removed from the substrate and milled by ultrasound to form aqueous solutions of colloidal Si nanopartiles. The fabricated Si-based nanocrystals present a promising object for theranostics, combining imaging functionality based on PL emission and a series of therapy functionalities (photo and radiofrequency hyperthermia, photodynamic therapy).
An integrated hardware–software approach was proposed to record the analytical response of sensor matrices exposed for a long time to liquid hydrocarbons and their vapors. A cell was designed and ...3D-printed to detect hydrocarbons by photonic-crystal sensor matrices with computer recording and accumulation of the diffuse reflectance spectra with subsequent metrological signal processing. The low content of volatile organic compounds in the air of the working area was determined, and the obtained data agree well with the stages of the working cycle in paint and varnish production. The statistical significance of the changes in the analytical signal of the photonic-crystal sensor that were caused by the time variation of the concentration of hydrocarbons was confirmed.
Photothermal properties of boron (B) nanoparticles (NPs) synthesized by pulsed laser ablation in liquid (PLAL) are studied. It is found that B NPs have high optical extinction coefficient in the near ...infrared (IR) region, in particular, its value was 0.2 l/(cm g) at a wavelength of 800 nm. It is shown that aqueous suspensions of B NPs can be heated during laser irradiation with a wavelength of 830 nm and a radiation power of 1 W. Here, the temperature increase varied from 6.5 to 36°C under the increase of the particle concentration from 0.04 to 0.8 g/L; while the relevant parameter in the absence of particles was 2°C. B NPs were able to provide a stable photothermal response during several irradiation cycles. The results evidence a high potential of B NPs as sensitizers of photothermal therapy (PTT).
A corrected energy dependence of the depth of the maximum in the wide range of energies 10
15
to 10
18
eV is obtained using data collected at the Tunka-133 facility over 7 years of operation ...(2009–2017) and the TAIGA-HiSCORE facility in the 2019–2020 season. At the highest energies, our results match those of the Pierre Auger observatory. The results are converted to parameter ❬ln
A
❭, which characterizes the mean EAS composition.
The Tunka-133 Cherenkov complex for recording extensive air showers (EAS) collected data over seven winters from 2009 to 2017. The differential energy spectra of all particles was acquired in the 6 × ...10
15
–3 × 10
18
eV range of energies over 2175 h. The TAIGA-HiSCORE complex is continually being expanded and upgraded. Data acquired by 30 first-line stations over 35 days during the period 2017–2018 is analyzed in this work. As at the Tunka-133 setup, the primary particle energies above 10
15
eV are measured using the density of the Cherenkov light flux at a distance of 200 m from a shower’s axis. Data on lower energies are collected by determining the energy of the light flux near a shower’s axis. This results in a spectrum of 2 × 10
14
–10
17
eV. The combined spectrum for the two systems covers a range of 2 × 10
14
–2 × 10
18
eV.
Status and First Results of TAIGA Tluczykont, M.; Astapov, I. I.; Awad, A. K. ...
Physics of atomic nuclei,
11/2021, Letnik:
84, Številka:
6
Journal Article
Recenzirano
The Tunka Advanced Instrument for Gamma-ray and cosmic ray Astrophysics (TAIGA) is a hybrid experiment for the measurement of Extensive Air Showers (EAS) with good spectral resolution in the TeV to ...PeV energy range. In this domain, the long-sought Pevatrons can be detected. Currently the TAIGA detector complex combines a two wide angle shower front Cherenkov light sampling timing arrays (HiSCORE and Tunka-133), two 4 m class, 10
aperture Imaging Air Cherenkov Telescopes (IACTs) and 240 m
surface and underground charged particle detector stations. Our goal is to introduce a new hybrid reconstruction technique, combining the good angular and shower core resolution of HiSCORE with the gamma-hadron separation power of imaging air Cherenkov telescopes. This approach allows to maximize the effective area and simultaneously to reach a good gamma-hadron separation at low energies (few teraelectronvolts). At higher energies, muon detectors are planned to enhance gamma-hadron separation. During the commissioning phase of the first and second IACT, several sources were observed. First detections of known sources with the first telescope show the functionality of the TAIGA IACTs. Here, the status of the TAIGA experiment will be presented, along with first results from the current configuration.
Monte Carlo Simulation of the TAIGA Experiment Postnikov, E. B.; Astapov, I. I.; Bezyazeekov, P. A. ...
Bulletin of the Russian Academy of Sciences. Physics,
08/2019, Letnik:
83, Številka:
8
Journal Article
Recenzirano
—
The TAIGA (Tunka Advanced Instrument for cosmic ray physics and Gamma-ray Astronomy) experiment aims at observing gamma-rays in the energy range from 1 TeV to several 100 TeV. The operation of the ...observatory is based on a new hybrid approach that combines imaging air Cherenkov telescopes (IACTs) and wide-angle Cherenkov detectors (TAIGA-HiSCORE) for measuring times of extensive air shower (EAS) light front arrival. Monte Carlo simulations are compared to real data to determine the performance of the detector setup. Dedicated software and algorithms are described, model parameters are given, and an overview of the current status of model-based performance studies is presented.
Work is currently under way in the Tunka Valley, 50 km from Lake Baikal, to create the TAIGA gamma observatory for studying gamma radiation and cosmic ray fluxes in the 10
13
–10
18
eV range of ...energies. To detect gamma rays with energies above tens of TeV, a hybrid method of detecting showers is implemented. It is based on data obtained by the TAIGA Imaging Atmospheric Cherenkov Telescope (IACT) and the wide-angle TAIGA-HiSCORE array. The preliminary results from processing the telescope’s data for the low-energy region (>2–3 TeV) are presented. Joint events with energy more than 50 TeV are analyzed and compared to Monte Carlo calculations.
High-energy cosmic-ray research via the detection of Cherenkov radiation from extensive air showers was begun in the Tunka valley (50 km to the west from the southern extremity of Lake Baikal) in the ...early 1990s. A series of large arrays combined into the TAIGA (Tunka Advanced Instrument for cosmic-ray physics and Gamma Astronomy) astrophysical facility and designed to study gamma rays and charged cosmic rays have been created in the elapsed time. Descriptions of the facility arrays and the main results obtained while investigating high-energy cosmic rays are presented. Plans for a further development of the astrophysical facility are discussed.
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