7 results on '"Gavrin VN"'
Search Results
2. Solar structure and evolution.
- Author
-
Christensen-Dalsgaard, Jørgen
- Subjects
STELLAR evolution ,STELLAR structure ,SOLAR neutrinos ,SOLAR surface ,SOLAR cycle ,SOLAR magnetic fields ,LIGHT elements - Abstract
The Sun provides a critical benchmark for the general study of stellar structure and evolution. Also, knowledge about the internal properties of the Sun is important for the understanding of solar atmospheric phenomena, including the solar magnetic cycle. Here I provide a brief overview of the theory of stellar structure and evolution, including the physical processes and parameters that are involved. This is followed by a discussion of solar evolution, extending from the birth to the latest stages. As a background for the interpretation of observations related to the solar interior I provide a rather extensive analysis of the sensitivity of solar models to the assumptions underlying their calculation. I then discuss the detailed information about the solar interior that has become available through helioseismic investigations and the detection of solar neutrinos, with further constraints provided by the observed abundances of the lightest elements. Revisions in the determination of the solar surface abundances have led to increased discrepancies, discussed in some detail, between the observational inferences and solar models. I finally briefly address the relation of the Sun to other similar stars and the prospects for asteroseismic investigations of stellar structure and evolution. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
3. The production of Ar-37 using a thermal neutron reactor flux.
- Author
-
Kelly, D. G., Arnaud, Q., Brossard, A. E., Corcoran, E. C., Durnford, D., Gerbier, G., Faurschou, A., McDonald, J. M., Mumby, T., and Samuleev, P.
- Subjects
ISOTOPES ,THERMAL neutrons ,NUCLEAR activation analysis ,ARGON ,NANOPARTICLES - Abstract
Ar-37 has been prepared from micron- and nano- diameter CaO by irradiation in the predominantly thermal flux of a SLOWPOKE-2 reactor. A polyether ether ketone irradiation vial facilitates irradiation in vacuo to yield radio-argon as the sole gaseous product. Gamma-emitting Ar-41(T
1/2 = 110 min) is used to infer Ar-37 activity, although40 Ar(n, γ)41 Ar also occurs as a result of air entrapped within the CaO matrix. Less air is present in the nano-CaO matrix and more radio-argon is liberated to the gas phase. Using nano-CaO, 96 ± 10% of predicted Ar-41 is observed following Ar-41 diffusion to an un-irradiated container. [ABSTRACT FROM AUTHOR]- Published
- 2018
- Full Text
- View/download PDF
4. Phase stability and lithium loading capacity in a liquid scintillation cocktail.
- Author
-
Bergeron, Denis, Mumm, H., and Tyra, M.
- Subjects
LITHIUM ,LIQUID scintillation counting ,LIQUID scintillators ,SCINTILLATION counters ,EMULSIONS - Abstract
Liquid scintillation cocktails loaded with neutron capture agents such as Li are used in both neutron and neutrino detectors. For detectors designed to operate over extended timespans, long-term stability can be a concern. We demonstrate the identification of thermodynamically unstable emulsions as distinct from stable microemulsions, driving phase separation with centrifugation. Phase separation was identified by monitoring the quench indicating parameter, measured using an external Compton source. Samples were also characterized by dynamic light scattering, where in an extreme case, phase separation could be observed in real time. We describe a stable cocktail with 0.01 mass fraction added Li, a relatively high Li concentration. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
5. Global seismology of the Sun.
- Author
-
Basu, Sarbani
- Subjects
SEISMOLOGY ,HELIOSEISMOLOGY ,ROTATION of the Sun ,OSCILLATIONS ,SOLAR activity ,MATHEMATICAL models - Abstract
The seismic study of the Sun and other stars offers a unique window into the interior of these stars. Thanks to helioseismology, we know the structure of the Sun to admirable precision. In fact, our knowledge is good enough to use the Sun as a laboratory. We have also been able to study the dynamics of the Sun in great detail. Helioseismic data also allow us to probe the changes that take place in the Sun as solar activity waxes and wanes. The seismic study of stars other than the Sun is a fairly new endeavour, but we are making great strides in this field. In this review I discuss some of the techniques used in helioseismic analyses and the results obtained using those techniques. I focus on results obtained with global helioseismology, i.e., the study of the Sun using its normal modes of oscillation. I also briefly touch upon asteroseismology, the seismic study of stars other than the Sun, and discuss how seismic data of others stars are interpreted. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
6. Global seismology of the Sun.
- Author
-
Basu, Sarbani
- Subjects
SEISMOLOGY ,SUN ,HELIOSEISMOLOGY ,SOLAR activity ,OSCILLATIONS - Abstract
The seismic study of the Sun and other stars offers a unique window into the interior of these stars. Thanks to helioseismology, we know the structure of the Sun to admirable precision. In fact, our knowledge is good enough to use the Sun as a laboratory. We have also been able to study the dynamics of the Sun in great detail. Helioseismic data also allow us to probe the changes that take place in the Sun as solar activity waxes and wanes. The seismic study of stars other than the Sun is a fairly new endeavour, but we are making great strides in this field. In this review I discuss some of the techniques used in helioseismic analyses and the results obtained using those techniques. I focus on results obtained with global helioseismology, i.e., the study of the Sun using its normal modes of oscillation. I also briefly touch upon asteroseismology, the seismic study of stars other than the Sun, and discuss how seismic data of others stars are interpreted. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
7. Radioargon production through the irradiation of calcium oxide.
- Author
-
Egnatuk, Christine and Biegalski, Steven
- Subjects
ARGON isotopes ,IRRADIATION ,LIME (Minerals) ,NEUTRON flux ,RESEARCH reactors - Abstract
The production of radioargon through the irradiation of CaO was performed in an in-core facility within the The University of Texas at Austin MARK II TRIGA reactor. The major radioargon isotope produced was Ar via the Ca(n,α)Ar reaction pathway. The CaO powder was vacuumed sealed in a quartz ampoule. The sample was irradiated in a Cd-lined Al alloy canister for 2 h at 500 kW. After the irradiation, the sample was counted using an HPGe detector five times with increasing count times. Ar, K, K, and Ca were detected in the spectra. The induced activities of Ar, Ar, Ar, K, K, and Ca were calculated using a 63-group energy-dependent neutron flux determined utilizing a neutron energy flux profile calculated from a MCNPX model of the TRIGA reactor core. The production ratios generated from the model allowed for the estimation of induced Ar and Ar activities through the measured induced activities of Ar, K, K, and Ca. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.