| 1. |
- Abdu, Y. A., et al.
(författare)
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High-temperature cation ordering in olivine : an in situ Mossbauer study of synthetic (Mg0.55Fe0.45)(2) SiO4
- 2008
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Ingår i: Hyperfine Interactions. - : Springer Science and Business Media LLC. - 0304-3843 .- 1572-9540. ; 186:1-3, s. 99-103
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Tidskriftsartikel (refereegranskat)abstract
- High- temperature in situ Mossbauer spectroscopy measurements ( 300 950. C) were done on synthetic olivine of composition ( Mg0.55Fe0.45) 2 SiO4 (= Fa45) in order to study the distribution of Fe2+ over the M1 and M2 octahedral sites. The spectra are fit with two doublets, which are assigned to Fe2+ at the M1 ( smaller splitting) and M2 sites. The Fe2+ site- occupancies at M1 and M2, obtained from the Mossbauer relative areas, suggest that Fe2+ has a slight preference for the M1 site at temperatures below similar to 500. C, with a tendency of disordering around this temperature. At higher temperatures, Fe2+ again prefers to occupy the M1 site, where it shows a considerable order at this site up to 750C. At still higher temperatures, the spectra indicated partial reduction of the Fa- component into metallic iron and the resolution of the doublets was severely deteriorated.
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| 2. |
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| 3. |
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| 4. |
- Aryal, M. M., et al.
(författare)
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Understanding of nuclear quadrupole interactions of Cl-35, Br-79 and I-129 and binding energies of solid halogens at first-principles level
- 2007
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Ingår i: Hyperfine Interactions. - : Springer Science and Business Media LLC. - 0304-3843 .- 1572-9540. ; 176:1-3, s. 51-57
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Tidskriftsartikel (refereegranskat)abstract
- This paper deals with the understanding at a first-principles level of the nuclear quadrupole interaction (NQI) parameters of solid chlorine, bromine and iodine as well as the intermolecular binding of these molecules in the solid. The electronic structure investigations that we have carried out to study these properties of the solid halogens are based on the Hartree-Fock Cluster approach using the Roothaan variational procedure with electron correlation effects included using many-body perturbation theory with the empty orbitals used in the perturbation theory investigations for the excited states. The results of our investigations provide good agreement with the measured NQI parameters primarily from the Hartree-Fock one electron wave-functions with many-body effects making minor contributions. The binding (dissociation) energies for the molecules with the solid state environment on the other hand arises from intermolecular many body effects identified as the Van der Waals attraction with one-electron Hartree-Fock contribution being repulsive in nature.
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| 5. |
- Balkeståhl, Li Caldeira, et al.
(författare)
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Prospects for pp rarr YY studies at PANDA
- 2014
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Ingår i: Hyperfine Interactions. - : Springer Science and Business Media LLC. - 0304-3843 .- 1572-9540. ; 229:1-3, s. 79-83
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Tidskriftsartikel (refereegranskat)abstract
- Strangeness and charm production provide an excellent probe of QCD in the confinement domain. With the PANDA detector at FAIR, this can be studied in e.g., hyperon production in the pp rarr YY reactions. In PANDA, all ground state strange hyperons and single charmed Lambda's will be accessible. Simulations show that the differential cross sections and spin observables can be well reconstructed for these reaction channels.
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| 6. |
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| 7. |
- Boezio, M., et al.
(författare)
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The PAMELA experiment and antimatter in the universe
- 2014
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Ingår i: Hyperfine Interactions. - : Springer Science and Business Media LLC. - 0304-3843 .- 1572-9540. ; 228:1-3, s. 101-109
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Tidskriftsartikel (refereegranskat)abstract
- On the 15th of June 2006, the PAMELA satellite-borne experiment was launched from the Baikonur cosmodrome and it has been collecting data since July 2006. The primary scientific goal is the measurement of the antiproton and positron energy spectra. Antiparticles are a natural component of the cosmic radiation being produced in the interaction between cosmic rays and the interstellar matter. They have been shown to be extremely interesting for understanding the propagation mechanisms of cosmic rays. Furthermore, novel sources of primary cosmic-ray antiparticles of either astrophysical or exotic origin (e.g. annihilation of dark matter particles) can also be probed. In this paper we review the PAMELA antiparticle results and their significance for the field of astroparticle physics.
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| 8. |
- Boezio, M., et al.
(författare)
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The PAMELA space mission for antimatter and dark matter searches in space
- 2012
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Ingår i: Hyperfine Interactions. - : Springer Science and Business Media LLC. - 0304-3843 .- 1572-9540. ; 213:1-3, s. 147-158
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Tidskriftsartikel (refereegranskat)abstract
- The PAMELA satellite-borne experiment has presented new results on cosmic-ray antiparticles that can be interpreted in terms of DM annihilation or pulsar contribution. The instrument was launched from the Baikonur cosmodrome and it has been collecting data since July 2006. The combination of a permanent magnet silicon strip spectrometer and a silicon-tungsten imaging calorimeter allows precision studies of the charged cosmic radiation to be conducted over a wide energy range with high statistics. The primary scientific goal is the measurement of the antiproton and positron energy spectrum in order to search for exotic sources. PAMELA is also searching for primordial antinuclei (anti-helium), and testing cosmic-ray propagation models through precise measurements of the antiparticle energy spectrum and precision studies of light nuclei and their isotopes. This talk illustrates the most recent scientific results obtained by the PAMELA experiment.
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| 9. |
- Burghart, FJ, et al.
(författare)
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Muons and muonium in Zn-spinels
- 1997
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Ingår i: HYPERFINE INTERACTIONS. - : BALTZER SCI PUBL BV. - 0304-3843. ; 106:1-4, s. 187-192
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- We have studied the magnetic spinel (Zn)[Fe-2]O-4 (T-N approximate to 10.5 K) and the non-magnetic spinels (Zn)[Al-2]O-4, (Zn)[Ga-2]O-4, (Zn)[ZnTi]O-4 and (Zn)[ZnSn]O-4, both with surface and decay channel muons. In (Zn)[Fe-2]O-4 the relaxation rate incre
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| 10. |
- Butler, E., et al.
(författare)
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Towards antihydrogen trapping and spectroscopy at ALPHA
- 2011
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Ingår i: Hyperfine Interactions. - : Springer Science and Business Media LLC. - 0304-3843 .- 1572-9540. ; 199:1, s. 39-48
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Tidskriftsartikel (refereegranskat)abstract
- Spectroscopy of antihydrogen has the potential to yield high-precision tests of the CPT theorem and shed light on the matter-antimatter imbalance in the Universe. The ALPHA antihydrogen trap at CERN’s Antiproton Decelerator aims to prepare a sample of antihydrogen atoms confined in an octupole-based Ioffe trap and to measure the frequency of several atomic transitions. We describe our techniques to directly measure the antiproton temperature and a new technique to cool them to below 10 K. We also show how our unique position-sensitive annihilation detector provides us with a highly sensitive method of identifying antiproton annihilations and effectively rejecting the cosmic-ray background.
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