66 research outputs found
X-ray radiation from ions with K-shell vacancies
Abstract New types of space resolved X-ray spectra produced in light matter experiments with high intensity lasers have been investigated experimentally and theoretically. This type of spectra is characterised by the disappearance of distinct resonance line emission and the appearance of very broad emission structures due to the dielectronic satellite transitions associated to the resonance lines. Atomic data calculations have shown, that rather exotic states with K-shell vacancies are involved. For quantitative spectra interpretation we developed a model for dielectronic satellite accumulation (DSA-model) in cold dense optically thick plasmas which are tested by rigorous comparison with space resolved spectra from ns-lasers. In experiments with laser intensities up to 10 19 W/cm 2 focused into nitrogen gas targets, hollow ion configurations are observed by means of soft X-ray spectroscopy. It is shown that transitions in hollow ions can be used for plasma diagnostic. The determination of the electron temperature in the long lasting recombining regime is demonstrated. In Light-matter interaction experiments with extremely high contrast (up to 10 10 ) short pulse (400 fs) lasers electron densities of n e ≈3×10 23 cm −3 at temperatures between kT e =200–300 eV have been determined by means of spectral simulations developed previously for ns-laser produced plasmas. Expansion velocities are determined analysing asymmetric optically thick line emission. Further, the results are checked by observing the spectral windows involving the region about the He α -line and the region from the He β -line to the He-like continuum. Finally, plasmas of solid density are characteristic in experiments with heavy ion beams heating massive targets. We report the first spectroscopic investigations in plasmas of this type with results on solid neon heated by Ar-ions. A spectroscopic method for the determination of the electron temperature in extreme optically thick plasmas is developed
Large neutrino telescope Baikal-GVD: recent status
The Baikal-GVD is a deep-underwater neutrino telescope being constructed in
Lake Baikal. After the winter 2023 deployment campaign the detector consists of
3456 optical modules installed on 96 vertical strings. The status of the
detector and progress in data analysis are discussed in present report. The
Baikal-GVD data collected in 2018-2022 indicate the presence of cosmic neutrino
flux in high-energy cascade events consistent with observations by the IceCube
neutrino telescope. Analysis of track-like events results in identification of
first high-energy muon neutrino candidates. These and other results from
2018-2022 data samples are reviewed in this report
Studies of the ambient light of deep Baikal waters with Baikal-GVD
The Baikal-GVD neutrino detector is a deep-underwater neutrino telescope
under construction and recently after the winter 2023 deployment it consists of
3456 optical modules attached on 96 vertical strings. This 3-dimensional array
of photo-sensors allows to observe ambient light in the vicinity of the
Baikal-GVD telescope that is associated mostly with water luminescence. Results
on time and space variations of the luminescent activity are reviewed based on
data collected in 2018-2022
Monitoring of optical properties of deep waters of Lake Baikal in 2021-2022
We present the results of the two-year (2021-2022) monitoring of absorption
and scattering lengths of light with wavelength 400-620 nm within the effective
volume of the deep underwater neutrino telescope Baikal-GVD, which were
measured by a device Baikal-5D No.2. The Baikal-5D No.2. was installed during
the 2021 winter expedition at a depth of 1180 m. The absorption and scattering
lengths were measured every week in 9 spectral points. The device Baikal-5D
No.2 also has the ability to measure detailed scattering and absorption
spectra. The data obtained make it possible to estimate the range of changes in
the absorption and scattering lengths over a sufficiently long period of time
and to investigate the relationship between the processes of changes in
absorption and scattering. An analysis was made of changes in absorption and
scattering spectra for the period 2021-2022
Search for directional associations between Baikal Gigaton Volume Detector neutrino-induced cascades and high-energy astrophysical sources
Baikal-GVD has recently published its first measurement of the diffuse
astrophysical neutrino flux, performed using high-energy cascade-like events.
We further explore the Baikal-GVD cascade dataset collected in 2018-2022, with
the aim to identify possible associations between the Baikal-GVD neutrinos and
known astrophysical sources. We leverage the relatively high angular resolution
of the Baikal-GVD neutrino telescope (2-3 deg.), made possible by the use of
liquid water as the detection medium, enabling the study of astrophysical point
sources even with cascade events. We estimate the telescope's sensitivity in
the cascade channel for high-energy astrophysical sources and refine our
analysis prescriptions using Monte-Carlo simulations. We primarily focus on
cascades with energies exceeding 100 TeV, which we employ to search for
correlation with radio-bright blazars. Although the currently limited neutrino
sample size provides no statistically significant effects, our analysis
suggests a number of possible associations with both extragalactic and Galactic
sources. Specifically, we present an analysis of an observed triplet of
neutrino candidate events in the Galactic plane, focusing on its potential
connection with certain Galactic sources, and discuss the coincidence of
cascades with several bright and flaring blazars.Comment: 10 pages, 3 figure
Nurses' perceptions of aids and obstacles to the provision of optimal end of life care in ICU
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