| 1. |
- Abdu, Y. A., et al.
(author)
-
High-temperature cation ordering in olivine : an in situ Mossbauer study of synthetic (Mg0.55Fe0.45)(2) SiO4
- 2008
-
In: Hyperfine Interactions. - : Springer Science and Business Media LLC. - 0304-3843 .- 1572-9540. ; 186:1-3, s. 99-103
-
Journal article (peer-reviewed)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.
|
|
| 2. |
|
|
| 3. |
- Aryal, M. M., et al.
(author)
-
Understanding of nuclear quadrupole interactions of Cl-35, Br-79 and I-129 and binding energies of solid halogens at first-principles level
- 2007
-
In: Hyperfine Interactions. - : Springer Science and Business Media LLC. - 0304-3843 .- 1572-9540. ; 176:1-3, s. 51-57
-
Journal article (peer-reviewed)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.
|
|
| 4. |
- Balkeståhl, Li Caldeira, et al.
(author)
-
Prospects for pp rarr YY studies at PANDA
- 2014
-
In: Hyperfine Interactions. - : Springer Science and Business Media LLC. - 0304-3843 .- 1572-9540. ; 229:1-3, s. 79-83
-
Journal article (peer-reviewed)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.
|
|
| 5. |
- Boezio, M., et al.
(author)
-
The PAMELA experiment and antimatter in the universe
- 2014
-
In: Hyperfine Interactions. - : Springer Science and Business Media LLC. - 0304-3843 .- 1572-9540. ; 228:1-3, s. 101-109
-
Journal article (peer-reviewed)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.
|
|
| 6. |
- Boezio, M., et al.
(author)
-
The PAMELA space mission for antimatter and dark matter searches in space
- 2012
-
In: Hyperfine Interactions. - : Springer Science and Business Media LLC. - 0304-3843 .- 1572-9540. ; 213:1-3, s. 147-158
-
Journal article (peer-reviewed)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.
|
|
| 7. |
- Butler, E., et al.
(author)
-
Towards antihydrogen trapping and spectroscopy at ALPHA
- 2011
-
In: Hyperfine Interactions. - : Springer Science and Business Media LLC. - 0304-3843 .- 1572-9540. ; 199:1, s. 39-48
-
Journal article (peer-reviewed)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.
|
|
| 8. |
- Cedervall, Johan, et al.
(author)
-
Mössbauer study of the magnetocaloric compound AlFe2B2
- 2016
-
In: Hyperfine Interactions. - : Springer Science and Business Media LLC. - 0304-3843 .- 1572-9540. ; 237
-
Journal article (peer-reviewed)abstract
- Mössbauer spectroscopy in the ferromagnetic AlFe2B2 reveals Tc=299 K and shows good agreement with magnetic measurements. The crystals are plate-shaped. The flakes are found from X-ray diffraction to be in the crystallographic ac-plane in the orthorhombic system. The axes of the principle electric field gradient tensor are, by symmetry, colinear with the crystal a-, b- and c-axes. By using information about the quadrupole splitting and line asymmetry in the paramagnetic regime together with the quadrupole shift of the resonance lines in the ferromagnetic regime the magnetic hyperfine field direction is found to be in the ab-plane having an angle =40° to the b-axis.
|
|
| 9. |
- Difi, Siham, et al.
(author)
-
Role of iron in Na1.5Fe0.5Ti1.5(PO4)(3)/C as electrode material for Na-ion batteries studied by operando Mossbauer spectroscopy
- 2016
-
In: Hyperfine Interactions. - : Springer Science and Business Media LLC. - 0304-3843 .- 1572-9540.
-
Conference paper (peer-reviewed)abstract
- The role of iron in Na1.5Fe0.5Ti1.5(PO4)(3)/C electrode material for Na batteries has been studied by Fe-57 Mossbauer spectroscopy in operando mode. The potential profile obtained in the galvanostatic regime shows three plateaus at different voltages due to different reaction mechanisms. Two of them, at 2.2 and 0.3 V vs Na+/Na-0, have been associated to redox processes involving iron and titanium in Na1.5Fe0.5Ti1.5(PO4)(3). The role of titanium was previously elucidated for NaTi2(PO4)(3) and the effect of the substitution of Fe for Ti was investigated with 57Fe Mossbauer spectroscopy. We show that iron is an electrochemically active center at 2.2 V with the reversible Fe3+/Fe2+ transformation and then remains at the oxidation state Fe2+ along the sodiation until the end of discharge at 0 V.
|
|
| 10. |
- Dubey, Archana, et al.
(author)
-
Nuclear quadrupole interactions and electronic structure of BF3 center dot H2O complex
- 2007
-
In: Hyperfine Interactions. - : Springer Science and Business Media LLC. - 0304-3843 .- 1572-9540. ; 176:1-3, s. 45-50
-
Journal article (peer-reviewed)abstract
- This work deals with first-principles investigation of the electronic structure of the BF3 center dot H2O complex which is important in catalysis of organic reactions and polymerization. The dissociation energy of the BF3 center dot H2O complex and the nuclear quadrupole interaction parameters for the excited nuclear state F-19* (I = 5/2) of the fluorine nuclei have been studied. Our investigation shows that the complexation bond BO between the BF3 and H2O units is strongly influenced by the larger electronegativity of Oxygen as compared to Nitrogen in BF3 center dot NH3. The quadrupole coupling constants of F-19* and the asymmetry parameter are however quite close to those for BF3 center dot NH3. The likely reasons for these features of these two important catalytic systems are suggested.
|
|
| 11. |
- Eklöw, N, et al.
(author)
-
Magnetic-field dependence in electron-deuteron recombination at very low relative energy
- 2000
-
In: Hyperfine Interactions. - 0304-3843 .- 1572-9540. ; 127:1-4, s. 251-255
-
Journal article (peer-reviewed)abstract
- The rate coefficient for recombination of D+ with low-energy electrons has been measured at different magnetic fields in the interaction region of the electron cooler at CRYRING. It is found that the measured recombination rate coefficient is influenced by the magnetic field.
|
|
| 12. |
- Eneroth, Erik, et al.
(author)
-
Fe-hydroxysulphates from bacterial Fe2+ oxidation
- 2004
-
In: Proceedings of the 27th International Conference on the Applications of the Mössbauer Effect (ICAME 2003) (Hyperfine Interactions). - 0304-3843 .- 1572-9540. ; 156-57:1-4, s. 423-429
-
Conference paper (peer-reviewed)abstract
- Precipitates formed due to Fe(II)-oxidation catalysed by Acidithiobacillus ferrooxidans between pH 1.6 and 3.2 have been studied by powder X-ray diffraction, infrared spectroscopy and Mossbauer spectroscopy. The precipitates consist of well crystalline, ammonium-containing jarosite at pH 1.6, and mixtures of jarosite and poorly crystalline schwertmannite at pH 2.5 and 3.2. At low temperatures ( 10 and 20 K) the components of the two phases overlap strongly. Jarosites ordered (c. 45 K - defect antiferromagnetic) at temperatures well below the ordering temperature for schwertmannite (c. 80 K at pH 3.2 and c. 70 K at pH 2.5). Thus thermoscans measured between 100 and 10 K facilitates characterization of these two minerals when occurring in mixtures.
|
|
| 13. |
- Ericsson, Tore, et al.
(author)
-
Non-magnetic stainless steels reinvestigated : A small effective field component in external magnetic fields
- 2004
-
In: Hyperfine Interactions. - 0304-3843 .- 1572-9540. ; 156/157, s. 151-155
-
Journal article (peer-reviewed)abstract
- Three standard non-magnetic stainl ess steels of composition (wt%) Fe 70 Cr 19 Ni 11 , Fe 70 Cr 17 Ni 13 and Fe 69 Cr 18 . 5 Ni 10 . 3 Mn 1 . 8 Ti 0 . 4 have been investigated by Mössbauer spectroscopy (5–295 K and in external fields 7 T at room temperature) and ma gnetization measurements (10– 300 K) using a SQUID magnetometer. There are indications of a field induced ferromagnetic inter- action in the samples at room temperature
|
|
| 14. |
- Ericsson, Tore, et al.
(author)
-
Vacancy ordering in FeTSes-FeTS8 solid solutions studied by Mössbauer, X-ray and magnetization techniques
- 1994
-
In: Hyperfine Interactions. - 0304-3843 .- 1572-9540. ; 90:1, s. 515-520
-
Journal article (peer-reviewed)abstract
- Superstructures, due to cation vacancy ordering, form in the NiAs-related pseudobinary solid solution Fe7Se8-Fe7S8 close to both end compositions (Fe-7(SxSe1-x)(8) with x less than or equal to 0.15 and x greater than or equal to 0.85) during rapid cooling of quartz ampoules from 600 degrees C, according to X-ray diffractometry (XRD) and magnetization (SQUID) measurements. Mossbauer spectroscopy indicates local vacancy ordering in the whole interval, but XRD and SQUID data exclude long-range vacancy ordering when the anion proportion of sulphur is between 15% and 85%.
|
|
| 15. |
- Fedosseev, V. N., et al.
(author)
-
Ionization scheme development at the ISOLDE RILIS
- 2005
-
In: Hyperfine Interactions. - : Springer Science and Business Media LLC. - 0304-3843 .- 1572-9540. ; 162:1-4, s. 15-27
-
Journal article (peer-reviewed)abstract
- The resonance ionization laser ion source (RILIS) of the ISOLDE on-line isotope separation facility is based on the method of laser step-wise resonance ionization of atoms in a hot metal cavity. The atomic selectivity of the RILIS complements the mass selection process of the ISOLDE separator magnets to provide beams of a chosen isotope with greatly reduced isobaric contamination. Using a system of dye lasers pumped by copper vapour lasers, ion beams of 24 elements have been generated at ISOLDE with ionization efficiencies in the range of 0.5-15%. As part of the ongoing RILIS development off-line resonance ionization spectroscopy studies carried out in 2003 and 2004 have determined the optimal three-step ionization schemes for scandium, antimony, dysprosium and yttrium.
|
|
| 16. |
- Ferrow, Embaie, et al.
(author)
-
Oxidation of pyrite grains: A Mossbauer spectroscopy and mineral magnetism study
- 2005
-
In: Hyperfine Interactions. - : Springer Science and Business Media LLC. - 1572-9540 .- 0304-3843. ; 163:1-4, s. 95-108
-
Journal article (peer-reviewed)abstract
- Fe2+ in pyrite is found in a low-spin d(6) configuration, a necessary condition for diamagnetic and semi-conducting properties of material. The semi-conducting property of pyrite has been studied since the time when pyrite was used as a rectifier in early radios. Pyrite posses the highest possible crystal field stabilisation energy and offers a better altemative as solar material compared to Si- based materials. Unfortunately, pyrite is difficult to study due to its inherent deviation from stoichiometry and its ease of oxidation. Since pyrite and its oxidation products are all Fe-bearing phases, combining Mossbauer spectroscopy with mineral magnetic methods provides enough information to monitor the oxidation of pyrite in air and identify the different phases produced and their relation to different experimental parameters. For mm-sized grain samples, heating FeS2 at temperatures between 450 degrees C and 650 degrees C five different mineral assemblages are identified. FeS2 is oxidized to alpha-Fe2O3 along two separate routes: FeS2 -> FeSO4 -> epsilon-Fe2O3 -> alpha-Fe2O3; and FeS2 -> FeSO4 -> Fe-2 (SO4)(3) -> ss-Fe2O3 -> alpha-Fe2O3.
|
|
| 17. |
- Ferrow, Embaie, et al.
(author)
-
Reaction kinetics and oxidation mechanisms of the conversion of pyrite to ferrous sulphate: A Mossbauer spectroscopy study
- 2005
-
In: Hyperfine Interactions. - : Springer Science and Business Media LLC. - 1572-9540 .- 0304-3843. ; 163:1-4, s. 109-119
-
Journal article (peer-reviewed)abstract
- Pyrite undergoes a series of exothermic reactions during mine roasting to porous hematite. At low temperatures, the first non-refractive phase to form is ferrous sulphate and could be a cheaper alternative to hematite roasting for the mining industry. In this study, pyrite powder is heated in air at temperatures between 200 and 370 degrees C for 1 to 256 h in a temperature and time series. The rate of oxidation of pyrite to ferrous sulphate is modelled by combining the Arrhenius equation with the Weibull function to extract reliable thermodynamic data, including the energy of activation, the frequency factor and the overall order of reaction. From the thermodynamic data obtained, two possible oxidation mechanisms are recognized, depending on the bond dissociation energies of the S-S and Fe-S bonds in pyrite.
|
|
| 18. |
- Froelich, Piotr, et al.
(author)
-
Four-body treatment of the antihydrogen-positronium system : binding, structure, resonant states and collisions
- 2019
-
In: Hyperfine Interactions. - : Springer. - 0304-3843 .- 1572-9540.
-
Conference paper (peer-reviewed)abstract
- We have developed a coupled-rearrangement-channel method allowing the rigorous non-adiabatic treatment of the multi-channel scattering problem for four particles. We present the study of the binding, resonant and collisional properties of the (H) over bar -Ps system with the total angular momentum J = 0(+) (singlet positronic configuration). The binding energy, the life-times of the resonant states and the collisional cross sections are calculated and discussed. We present the preliminary cross sections for the elastic and inelastic (H) over bar -Ps scattering, notably for the excitation of Ps and for the rearrangement reaction producing the (H) over bar (+) ions.
|
|
| 19. |
- Gadelshin, V. M., et al.
(author)
-
First laser ions at the CERN-MEDICIS facility
- 2020
-
In: Hyperfine Interactions. - : Springer Science and Business Media LLC. - 0304-3843 .- 1572-9540. ; 241:1
-
Journal article (peer-reviewed)abstract
- The CERN-MEDICIS facility aims to produce emerging medical radionuclides for the theranostics approach in nuclear medicine with mass separation of ion beams. To enhance the radioisotope yield and purity of collected samples, the resonance ionization laser ion source MELISSA was constructed, and provided the first laser ions at the facility in 2019. Several operational tests were accomplished to investigate its performance in preparation for the upcoming production of terbium radioisotopes, which are of particular interest for medical applications. © 2020, The Author(s).
|
|
| 20. |
- Gismelseed, A. M., et al.
(author)
-
Investigations of Al-Dalang and Al-Hawashat meteorites
- 2016
-
In: Hyperfine Interactions. - : Springer Science and Business Media LLC. - 0304-3843 .- 1572-9540.
-
Conference paper (peer-reviewed)abstract
- Mossbauer spectroscopy, X-ray diffraction (XRD) measurements, and electron microprobe analysis (EMPA) have been performed on two meteorites named Al-Dalang and Al-Hawashat after identifying their falling sites in the Western region of Sudan. These two meteorites are ordinary chondrites with similar mineralogy. XRD and EMPA show that the two specimens consist of primary olivine, ortho-pyroxene and later crystallising clino-pyroxene as reaction rims against plagioclase. Fe-metal phases are dominated by kamacite (approximate to 6 wt.% Ni) and minor amounts of tetrataenite (approximate to 52 wt.% Ni). Troilite (FeS) and alabandite (MnS) are optically observed as sulphide phases. The Mossbauer measurements at 295 and 78 K are in agreement with the above characterizations, showing at least two paramagnetic doublets which are assigned to olivine and pyroxene and magnetic sextets assigned to kamacite (hyperfine field approximate to 33.5 T) and troilite FeS (hyperfine field approximate to 31 T).
|
|
| 21. |
- Grzonka, D., et al.
(author)
-
Search for polarized antiproton production
- 2019
-
In: Hyperfine Interactions. - : Springer Nature. - 0304-3843 .- 1572-9540. ; 240
-
Journal article (peer-reviewed)abstract
- The production of antiprotons is studied in view of possible polarization effects as basis for a polarized antiproton beam. If antiprotons are produced with some polarization, a quite simple procedure for the generation of a polarized antiproton beam could be worked out. The experiments are performed at the CERN PS test beam T11 where secondary particles with momenta around 3.5 GeV/c are selected. The polarization analysis is performed by measuring the asymmetry of the elastic (p) over barp-scattering in the Coulomb-nuclear interference region. The detection system includes Cherenkov and tracking detectors for the particle identification and the 3d track reconstruction. Details on the detection system and the status of the analysis are given.
|
|
| 22. |
- Habs, D., et al.
(author)
-
The REX-ISOLDE project
- 2000
-
In: Hyperfine Interactions. - 0304-3843 .- 1572-9540. ; 129:1-4, s. 43-66
-
Journal article (peer-reviewed)abstract
- The Radioactive Beam Experiment REX-ISOLDE [1-3] is a pilot experiment at ISOLDE (CERN) testing the new concept of post acceleration of radioactive ion beams by using charge breeding of the ions in a high charge state ion source and the efficient acceleration of the highly charged ions in a short LINAC using modern ion accelerator structures. In order to prepare the ions for the experiments singly charged radioactive ions from the on-line mass separator ISOLDE will be cooled and bunched in a Penning trap, charge bred in an electron beam ion source (EBIS) and finally accelerated in the LINAC. The LINAC consists of a radiofrequency quadrupole (RFQ) accelerator, which accelerates the ions up to 0.3 MeV/u, an interdigital H-type (IH) structure with a final energy between 1.1 and 1.2 MeV/u and three seven gap resonators, which allow the variation of the final energy. With an energy of the radioactive beams between 0.8 MeV/u and 2.2 MeV/u a wide range of experiments in the field of nuclear spectroscopy, astrophysics and solid state physics will be addressed by REX-ISOLDE.
|
|
| 23. |
- Hobein, Matthias, 1981-, et al.
(author)
-
SMILETRAP II
- 2011
-
In: Hyperfine Interactions. - : Springer Netherlands. - 0304-3843 .- 1572-9540. ; 199:1-3, s. 141-150
-
Journal article (peer-reviewed)abstract
- The new Penning trap mass spectrometer SMILETRAP II has been set up at the AlbaNova Research Center, Stockholm. Based on the former spectrometer SMILETRAP I, it uses the merits of highly-charged ions to achieve high precision in the mass measurements. Various improvements over the SMILETRAP I setup will allow to routinely perform mass measurements with relative uncertainties of 10−10 and below. In this paper we will discuss the limitations of SMILETRAP I and present the corresponding improvements of SMILETRAP II. An overview on the SMILETRAP II setup is given.
|
|
| 24. |
- Huyse, M., et al.
(author)
-
Anomalies in the alpha-decay energies and half-lives of neutron-deficient Po isotopes
- 2001
-
In: Hyperfine Interactions. - 0304-3843 .- 1572-9540. ; 132:04-jan, s. 141-146
-
Journal article (peer-reviewed)abstract
- The transition rates of DeltaL = 0 alpha transitions in them lightest Po isotopes are considerably slower than the transition rates of the heavier ones, even leading to a considerable deviation in the classical Geiger-Nuttall plot. Evidence will be given that due to particle-hole excitations through the Z = 82 proton shell, the groundstate of the lighter Po isotopes becomes deformed and direct alpha decay to the spherical groundstate of the corresponding Ph isotopes is highly retarded.
|
|
| 25. |
- Häggström, Lennart, et al.
(author)
-
Mössbauer and magnetisation studies of iron oxide nanocrystals
- 2008
-
In: Hyperfine Interactions. - : Springer Science and Business Media LLC. - 0304-3843 .- 1572-9540. ; 183:1-3, s. 49-53
-
Journal article (peer-reviewed)abstract
- Monodisperse iron oxide nanocrystals have been produced following non-hydrolytic, thermal decomposition routes. Spherically shaped particles with diameter of 4 and 12 nm and cubic shaped particles with an edge length of 9 nm have been studied. The particles have been shown to consist of mainly maghemite. A reduction of the saturation magnetic hyperfine field is observed for the 4 nm particles as compared to the corresponding bulk value. The anisotropy energy determined from the temperature variation of the magnetic hyperfine field was strongly enhanced for the 4 nm particles.
|
|
