| 1. |
- Fretwell, P., et al.
(författare)
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Bedmap2 : improved ice bed, surface and thickness datasets for Antarctica
- 2013
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Ingår i: The Cryosphere. - : Copernicus GmbH. - 1994-0416 .- 1994-0424. ; 7:1, s. 375-393
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Tidskriftsartikel (refereegranskat)abstract
- We present Bedmap2, a new suite of gridded products describing surface elevation, ice-thickness and the seafloor and subglacial bed elevation of the Antarctic south of 60 degrees S. We derived these products using data from a variety of sources, including many substantial surveys completed since the original Bedmap compilation (Bedmap1) in 2001. In particular, the Bedmap2 ice thickness grid is made from 25 million measurements, over two orders of magnitude more than were used in Bedmap1. In most parts of Antarctica the subglacial landscape is visible in much greater detail than was previously available and the improved data-coverage has in many areas revealed the full scale of mountain ranges, valleys, basins and troughs, only fragments of which were previously indicated in local surveys. The derived statistics for Bedmap2 show that the volume of ice contained in the Antarctic ice sheet (27 million km(3)) and its potential contribution to sea-level rise (58 m) are similar to those of Bedmap1, but the mean thickness of the ice sheet is 4.6% greater, the mean depth of the bed beneath the grounded ice sheet is 72m lower and the area of ice sheet grounded on bed below sea level is increased by 10 %. The Bedmap2 compilation highlights several areas beneath the ice sheet where the bed elevation is substantially lower than the deepest bed indicated by Bedmap1. These products, along with grids of data coverage and uncertainty, provide new opportunities for detailed modelling of the past and future evolution of the Antarctic ice sheets.
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| 2. |
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| 3. |
- Miyoshi, Y., et al.
(författare)
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The energization and radiation in geospace (ERG) project
- 2012
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Ingår i: Dynamics of The Earth's Radiation Belts and Inner Magnetosphere. - : American Geophysical Union (AGU). - 9780875904894 ; , s. 103-116
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Konferensbidrag (refereegranskat)abstract
- The Energization and Radiation in Geospace (ERG) project for solar cycle 24 will explore how relativistic electrons in the radiation belts are generated during space storms. This geospace exploration project consists of three research teams: the ERG satellite observation team, the ground-based network observation team, and the integrated data analysis/simulation team. Satellite observation will provide in situ measurements of features such as the plasma distribution function, electric and magnetic fields, and plasma waves, whereas remote sensing by ground-based observations using, for example, HF radars, magnetometers, optical instruments, and radio wave receivers will provide the global state of the geospace. Various kinds of data will be integrated and compared with numerical simulations for quantitative understanding. Such a synergetic approach is essential for comprehensive understanding of relativistic electron generation/loss processes through crossenergy and cross-regional coupling in which different plasma populations and regions are dynamically coupled with each other. In addition, the ERG satellite will utilize a new and innovative measurement technique for wave-particle interactions that can directly measure the energy exchange process between particles and plasma waves. In this paper, we briefly review some of the profound problems regarding relativistic electron accelerations and losses that will be solved by the ERG project, and we provide an overview of the project.
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| 4. |
- Ferreira da Silva, A., et al.
(författare)
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Improved theoretical model of InN optical properties
- 2014
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Ingår i: Physica Status Solidi (C) Current Topics in Solid State Physics. - : Wiley. - 1862-6351. ; 11:3-4, s. 581-584
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Tidskriftsartikel (refereegranskat)abstract
- The optical properties of InN are investigated theoretically by employing the projector augmented wave (PAW) method within Green's function and the screened Coulomb interaction approximation (GWo). The calculated results are compared to previously reported calculations which use local density approximation combined with the scissors-operator approximation. The results of the present calculation are compared with reported values of the InN bandgap and with low temperature near infrared luminescence measurements of InN films deposited by a modified Ion Beam Assisted Deposition technique.
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| 5. |
- Kumar, Mukesh, et al.
(författare)
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Bulk properties of InN films determined by experiments and theory
- 2014
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Ingår i: Journal of Crystal Growth. - : Elsevier BV. - 0022-0248 .- 1873-5002. ; 403, s. 124-127
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Tidskriftsartikel (refereegranskat)abstract
- Built properties of InN are determined by combining experimental and theoretical studies. In this work, we produced high quality InN film deposited on GaN templates by a modified ion beam assisted deposition technique confirmed by low temperature photoluminescence and absorption. The density of states, real and imaginary parts of the complex dielectric function and the absorption coefficient are calculated by means of first principles beyond density functional theory. The quasi particle aspect is described in the framework of a quasi particle method (the GW approximation). The calculated band gap energy is similar to 0.8 eV whereas significance in the optical absorption occurs at similar to 1.2 eV, which are consistent with both luminescence and absorption results. The Bethe-Salpeter equation is utilized to model the two particle exciton interactions, revealing a strong excitonic peak just below the absorption edge of InN.
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| 6. |
- Takada, A., et al.
(författare)
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SMILE-II : Observation of celestial and atmosphereic MeV gamma rays using a balloon-borne wide fields of view Electron-Tracking Compton Camera
- 2011
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Ingår i: Proceedings of the 20th ESA Symposium on European Rocket and Balloon Programmes and Related Research. - Noordwijk : European Space Agency, ESA. ; , s. 567-571
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Konferensbidrag (refereegranskat)abstract
- We have developed an Electron Tracking Compton Camera (ETCC) as an MeV gamma-ray telescope in the next generation. The ETCC consists of a gaseous time projection chamber and a position sensitive scintillation camera. We had launched a small size ETCC loaded on a balloon in 2006, and it was successful to obtain the fluxes of diffuse cosmic and atmospheric gamma rays in the energy range between 125 keV and 1.25 MeV. As the next flight (SMILE-II), we planned a long duration flight using a circumpolar balloon launched from Kiruna, and it will observe the celestial bright sources and the atmospheric gamma-ray burst due to the relativistic electron from the radiation belt. In this paper, we report the concepts of our detector and the performance of the SMILE-Il prototype.
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| 7. |
- Takahashi, H., et al.
(författare)
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A thermal-neutron detector with a phoswich system of LiCaAlF6 and BGO crystal scintillators onboard PoGOLite
- 2010
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Ingår i: 2010 IEEE Nuclear Science Symposium, Medical Imaging Conference, NSS/MIC 2010 and 17th International Workshop on Room-Temperature Semiconductor X-ray and Gamma-ray Detectors, RTSD 2010. ; , s. 32-37
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Konferensbidrag (refereegranskat)abstract
- To measure the flux of atmospheric neutrons and study the neutron contribution to the background of the main detector of the PoGOLite (Polarized Gamma-ray Observer) balloon-borne experiment, a thermal-neutron detector with a phoswich system of LiCaAlF6 (Eu) and BGO crystal scintillators is developed. The performance to separate thermal-neutron events from those of gamma-rays and charged particles is validated with 252Cf on ground. The detector is attached to the PoGOLite instrument and is launched in 2011 from the Esrange facility in the North of Sweden. Although the emission wavelength of the LiCaAlF6 (Ce) is 300 nm and overlaps with the absorption wavelength of the BGO, the phoswich capability of the LiCaAlF6 (Ce) with the BGO is also confirmed with installing a waveform shifter.
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