| 1. |
- Behringer, Hans, et al.
(författare)
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Dynamics of biomolecular processes PREFACE
- 2013
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Ingår i: Physica Scripta. - : IOP Publishing. - 0031-8949 .- 1402-4896. ; 87:5, s. 058501-
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 2. |
- Clementson, Joel, et al.
(författare)
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Spectroscopy of M-shell x-ray transitions in Zn-like through Co-like W
- 2010
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Ingår i: Physica Scripta. - : IOP Publishing. - 0031-8949 .- 1402-4896. ; 81:1, s. 1-015301
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Tidskriftsartikel (refereegranskat)abstract
- The M-shell x-ray emission of highly charged tungsten ions has been investigated at the Livermore electron beam ion trap facility. Using the SuperEBIT electron beam ion trap and a NASA x-ray calorimeter array, transitions connecting to levels of the ground configurations in the 1500–3600 eV spectral range of zinc-like W44+ through cobalt-like W47+ have been measured. The measured spectra are compared with theoretical line positions and emissivities calculated using the FAC code.
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| 3. |
- DiJulio, Douglas, et al.
(författare)
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Shell model based Coulomb excitation gamma-ray intensity calculations in Sn-107
- 2012
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Ingår i: Physica Scripta. - 0031-8949. ; T150
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Tidskriftsartikel (refereegranskat)abstract
- In this work, we present recent shell model calculations, based on a realistic nucleon-nucleon interaction, for the light Sn-107,Sn-109 nuclei. By combining the calculations with the semi-classical Coulomb excitation code GOSIA, a set of gamma-ray intensities has been generated. The calculated intensities are compared with the data from recent Coulomb excitation studies in inverse kinematics at the REX-ISOLDE facility with the nucleus Sn-107. The results are discussed in the context of the ordering of the single-particle orbits relative to Sn-100.
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| 4. |
- Esposito, Giampiero, et al.
(författare)
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Towards obtaining Green functions for a Casimir cavity in de Sitter spacetime
- 2015
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Ingår i: Physica Scripta. - : IOP Publishing. - 0031-8949 .- 1402-4896. ; 90:7
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Tidskriftsartikel (refereegranskat)abstract
- Recent work in the literature has studied rigid Casimir cavities in a weak gravitational field, or in de Sitter spacetime, or yet other spacetime models. The present review paper studies the difficult problem of direct evaluation of scalar Green functions for a Casimir-type apparatus in de Sitter spacetime. Working to first order in the small parameter of the problem, i.e. twice the gravity acceleration times the plates' separation divided by the speed of light in vacuum, suitable coordinates are considered for which the differential equations obeyed by the zeroth- and first-order Green functions can be solved in terms of special functions. This result can be used, in turn, to obtain, via the point-split method, the regularized and renormalized energy–momentum tensor both in the scalar case and in the physically more relevant electromagnetic case.
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| 5. |
- Galant, Grzegorz, 1985, et al.
(författare)
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Simplified models for the nonlinear evolution of two fast-particle-driven modes near the linear stability threshold
- 2011
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Ingår i: Physica Scripta. - : IOP Publishing. - 1402-4896 .- 0031-8949. ; 83:5, s. 055502-
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Tidskriftsartikel (refereegranskat)abstract
- An analytical model that is based on purely differential equations of the nonlinear dynamics of two plasma modes driven resonantly by high-energy ions near the instability threshold is presented here. The well-known integro-differential model of Berk and Breizman (BB) extended to the case of two plasma modes is simplified here to a system of two coupled nonlinear differential equations of fifth order. The effects of the Krook, diffusion and dynamical friction (drag) relaxation processes are considered, whereas shifts in frequency and wavenumber between the modes are neglected. In spite of these simplifications the main features of the dynamics of the two plasma modes are retained. The numerical solutions to the model equations show competition between the two modes for survival, oscillations, chaotic regimes and 'blow-up' behavior, similar to the BB model.
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| 6. |
- Gellanki, Jnaneswari, et al.
(författare)
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High-spin Structure Studies in 62Zn
- 2012
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Ingår i: Physica Scripta. - 0031-8949. ; T150
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Tidskriftsartikel (refereegranskat)abstract
- A detailed experimental study of the Zn-62 nucleus was conducted by combining the data sets from four fusion-evaporation reaction experiments. Apart from the previous published data, the present results include ten new rotational band structures and two new superdeformed bands. The GAMMASPHERE Ge-detector array in conjunction with the 4 pi charged-particle detector array Microball allowed for detection of gamma-rays in coincidence with evaporated light particles. The deduced level scheme includes some 260 excited states, which are connected with 450 gamma-ray transitions. The multipolarities have been assigned via directional correlations of gamma-rays emitted from oriented states. The experimental characteristics of the rotational bands are analyzed and compared with the results from the cranked Nilsson-Strutinsky calculations.
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| 7. |
- Grumer, Jon, et al.
(författare)
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Unexpected transitions induced by spin-dependent, hyperfine and external magnetic-field interactions
- 2014
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Ingår i: Physica Scripta. - : IOP Publishing. - 0031-8949 .- 1402-4896. ; 89:11
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Tidskriftsartikel (refereegranskat)abstract
- Unexpected transitions are induced by weaker interactions not included in the gross structure model of the ion under investigation. We discuss different examples of such decay channels, starting with relativistic spin-induced transitions. These represented an important field of study a few decades ago, and we illustrate how some challenging cases can be treated very accurately with today's computational techniques, while close degeneracy sometimes still prevents ab initio methods from obtaining accurate results. For hyperfine induced transitions we review some recent results and discuss remaining challenges for experiment and theory. Finally, we discuss the newly opened field of accurate calculations for transitions induced by an external magnetic field and point to some examples of where these are accessible for experimental tests.
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| 8. |
- Hamamoto-Kuroda, Ikuko
(författare)
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Interplay between one-particle and collective degrees of freedom in nuclei
- 2016
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Ingår i: Physica Scripta. - : IOP Publishing. - 0031-8949 .- 1402-4896. ; 91:2
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Tidskriftsartikel (refereegranskat)abstract
- Some developments of nuclear-structure physics uniquely related to Copenhagen School are sketched based on theoretical considerations versus experimental findings and one-particle versus collective aspects. Based on my personal overview I pick up the following topics; (1) Study of vibration in terms of particle-vibration coupling; (2) one-particle motion in deformed and rotating potentials, and yrast spectroscopy in high-spin physics; (3) triaxial shape in nuclei: wobbling motion and chiral bands; (4) nuclear structure of drip line nuclei: in particular, shellstructure (or magic numbers) change and spherical or deformed halo phenomena; (5) shell structure in oblate deformation.
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| 9. |
- Heinasmaki, S., et al.
(författare)
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Distorted angular distribution of the 2p photoelectrons in argon
- 2013
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Ingår i: Physica Scripta. - : IOP Publishing. - 0031-8949 .- 1402-4896. ; 87:6
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Tidskriftsartikel (refereegranskat)abstract
- Two consecutive hemispherical electron energy analyzers have been used to measure the argon angular distribution of 2p photoelectron lines over two quadrants of the dipole plane. A significant anomaly in the intensity of the photolines is observed at several electron emission angles, suggesting asymmetry with respect to the electric field vector of synchrotron light. As a possible cause for the observed behavior, we consider an external field affecting the photoelectrons, and show that it is capable of breaking the left-right asymmetry of the angular distribution, giving rise qualitatively to the observed behavior.
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| 10. |
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| 11. |
- Kivimaeki, A., et al.
(författare)
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On the production of N-2(+) ions at the N 1s edge of the nitrogen molecule
- 2013
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Ingår i: Physica Scripta. - : IOP Publishing. - 0031-8949 .- 1402-4896. ; 87:6
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Tidskriftsartikel (refereegranskat)abstract
- The N-2(+) ion yield of the N-2 molecule has been measured at the N 1s -> Rydberg excitations. It displays Fano-type line shapes due to interference between direct outer-valence photoionization and participator decay of the core-excited Rydberg states. The N-2(+) ion yield is compared with the total intensity of the outer-valence photoelectron lines obtained recently with electron spectroscopy (Kivimaki et al 2012 Phys. Rev. A 86 012516). The increasing difference between the two curves at the higher core-to-Rydberg excitations is most likely due to soft x-ray emission processes that are followed by autoionization. The results also suggest that resonant Auger decay from the core-valence doubly excited states contributes to the N-2(+) ion yield at the photon energies that are located on both sides of the N 1s ionization limit.
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| 12. |
- Kristensson, Gerhard
(författare)
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The polarizability and the capacitance change of a bounded object in a parallel plate capacitor
- 2012
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Ingår i: Physica Scripta. - : IOP Publishing. - 0031-8949 .- 1402-4896. ; 86:3
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Tidskriftsartikel (refereegranskat)abstract
- Abstract in UndeterminedA method for solving the change in capacitance (or charge) if an object is introduced in a parallel plate capacitor is developed. The integral representation of the potential is exploited in a systematic way to solve the potential everywhere inside the capacitor. In particular, the change in capacitance is extracted. The method shows similarities with the null field approach for solving dynamic problems.
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| 13. |
- Lastusaari, M., et al.
(författare)
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Valences of dopants in Eu2+ persistent luminescence materials
- 2014
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Ingår i: Physica Scripta. - : IOP Publishing. - 0031-8949 .- 1402-4896. ; 89:4
-
Tidskriftsartikel (refereegranskat)abstract
- The existence and effect of different rare earth (R2+/3+/IV) ions in SrAl2O4:Eu2+, R3+ and M2MgSi2O7:Eu2+, R3+ (M: Sr, Ba) persistent luminescence materials was studied with XANES (x-ray absorption near edge structure) measurements at HASYLAB/DESY (Hamburg, Germany) and MAX-lab (Lund, Sweden). The experiments were carried out at 298K for selected rare earth (co-) dopants (Eu2+; Ce3+, Nd3+, Sm3+, Dy3+ and Yb3+). The co-existence of Eu2+ and Eu3+ was observed in all materials. The co-dopants were always in the trivalent form.
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| 14. |
- Lestinsky, M., et al.
(författare)
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CRYRING@ESR: present status and future research
- 2015
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Ingår i: Physica Scripta. - 0031-8949 .- 1402-4896. ; T166
-
Tidskriftsartikel (refereegranskat)abstract
- The former storage ring CRYRING has been shipped from the Manne Siegbahn Laboratory in Stockholm to Darmstadt as a Swedish in-kind contribution to FAIR. At its new location downstream of ESR all ion species presently accessible in ESR can be transferred to CRYRING, in which ions with rigidities between 1.44 and 0.054 Tm can be stored. The original Swedish layout has been modified by reconfiguring the sequence of straight sections and by slightly increasing the circumference to ESR/2. Ions can be injected from ESR or from an independent 300 keV/u RFQ test injector. The instrumentation of the ring includes an RF drift tube system for acceleration and deceleration (1 T s(-1), with a possibility for an upgrade to 7 T s(-1)), electron cooling, a free experimental section, and both fast and slow extraction of ions. We report on the present progress of this project, give a prospective timeline, and summarize the new research which will be enabled by this project. First beam for commissioning of the storage ring is expected for 2015, final bakeout to restore ultrahigh vacuum conditions in 2016 and ion beams injected through ESR in similar to 2017.
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| 15. |
- Lestinsky, M., et al.
(författare)
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CRYRING@ESR: present status and future research
- 2015
-
Ingår i: Physica Scripta. - : IOP Publishing. - 1402-4896 .- 0031-8949. ; 2015:T166
-
Konferensbidrag (refereegranskat)abstract
- The former storage ring CRYRING has been shipped from the Manne Siegbahn Laboratory in Stockholm to Darmstadt as a Swedish in-kind contribution to FAIR. At its new location downstream of ESR all ion species presently accessible in ESR can be transferred to CRYRING, in which ions with rigidities between 1.44 and 0.054 Tm can be stored. The original Swedish layout has been modified by reconfiguring the sequence of straight sections and by slightly increasing the circumference to ESR/2. Ions can be injected from ESR or from an independent 300 keV/u RFQ test injector. The instrumentation of the ring includes an RF drift tube system for acceleration and deceleration (1 T s(-1), with a possibility for an upgrade to 7 T s(-1)), electron cooling, a free experimental section, and both fast and slow extraction of ions. We report on the present progress of this project, give a prospective timeline, and summarize the new research which will be enabled by this project. First beam for commissioning of the storage ring is expected for 2015, final bakeout to restore ultrahigh vacuum conditions in 2016 and ion beams injected through ESR in similar to 2017.
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| 16. |
- Li, M., et al.
(författare)
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A strong visible line in the spectrum of W11
- 2016
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Ingår i: Physica Scripta. - : IOP Publishing. - 0031-8949 .- 1402-4896. ; 91:10
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Tidskriftsartikel (refereegranskat)abstract
- We have investigated the visible spectrum of W11+ and found a very strong line at the wave length of 527.61 nm from the 4f135s25p2 (2F7/2-2F5/2) transition. We show that this line is strong since the excitation energy of the upper level opens up the possibility to capture a large population. We discuss the possibility that this strong line could be the unknown line seen in charge exchange spectra recorded at the JET fusion facility.
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| 17. |
- Malcheva, G., et al.
(författare)
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Lifetime measurements of even and odd states in neutral terbium (Tb I)
- 2013
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Ingår i: Physica Scripta. - : IOP Publishing. - 0031-8949 .- 1402-4896. ; 88:4
-
Tidskriftsartikel (refereegranskat)abstract
- Radiative lifetimes of 7 odd and 11 even parity states of Tb I (Z = 65) have been measured by the time resolved laser induced fluorescence method (TR-LIF). Experimental data for 9 out of the 18 states are obtained for the first time. The radiative lifetimes presented in this study are in good agreement with previous TR-LIF experimental results but systematically shorter than those obtained by the delayed coincidence technique.
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| 18. |
- Pal, L., et al.
(författare)
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Stochastic aspects of neutron slowing down processes
- 2010
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Ingår i: Physica Scripta. - : IOP Publishing. - 1402-4896 .- 0031-8949. ; 82:1
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a review of all the aspects of slowing down phenomena in which stochastic considerations of the process need to be taken into account. The cases both with and without absorption are treated. A consistent treatment is given of the energy distribution functions, the moments of collisions to slow down past a certain energy, the speed of neutrons and the slowing down time, with explicit expressions for the expectation and variance in all cases. Besides a compact and uniform derivation of known results, some new results are also presented.
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| 19. |
- Pfalzner, S., et al.
(författare)
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The formation of the solar system
- 2015
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Ingår i: Physica Scripta. - : IOP Publishing. - 0031-8949 .- 1402-4896. ; 90:6
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The solar system started to form about 4.56 Gyr ago and despite the long intervening time span, there still exist several clues about its formation. The three major sources for this information are meteorites, the present solar system structure and the planet-forming systems around young stars. In this introduction we give an overview of the current understanding of the solar system formation from all these different research fields. This includes the question of the lifetime of the solar protoplanetary disc, the different stages of planet formation, their duration, and their relative importance. We consider whether meteorite evidence and observations of protoplanetary discs point in the same direction. This will tell us whether our solar system had a typical formation history or an exceptional one. There are also many indications that the solar system formed as part of a star cluster. Here we examine the types of cluster the Sun could have formed in, especially whether its stellar density was at any stage high enough to influence the properties of today's solar system. The likelihood of identifying siblings of the Sun is discussed. Finally, the possible dynamical evolution of the solar system since its formation and its future are considered.
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| 20. |
- Sjöstrand, Torbjörn
(författare)
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Challenges for QCD theory: some personal reflections
- 2013
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Ingår i: Physica Scripta. - 0031-8949. ; T158
-
Tidskriftsartikel (refereegranskat)abstract
- At the LHC all processes are QCD ones, whether 'signal' or 'background'. In this review the frontiers of current QCD research are addressed, towards increased understanding, improved calculational precision, and role in potential future discoveries. Issues raised include: the limits of perturbative QCD calculations and parton distribution usage, the nature of multiparton interactions, the impact of colour reconnection on physical observables, the need for progress on hadronization modelling, the improvements of parton showers and their combination with the matrix-element description, the use of QCD concepts in Beyond-the-Standard-Model scenarios and the key position of event generators and other software in the successful exploration of LHC physics. On the way, several questions are posed, where further studies are needed.
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| 21. |
- Svensson, Bengt E Y
(författare)
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On the interpretation of quantum mechanical weak values
- 2014
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Ingår i: Physica Scripta. - 0031-8949. ; T163
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Tidskriftsartikel (refereegranskat)abstract
- After a brief review of how quantum mechanical weak measurements plus post-selection give rise to the weak value concept, I criticize an interpretation of a weak value as any sort of straightforward, bona fide property of the system under investigation.
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| 22. |
- Törnqvist, Hans, 1985, et al.
(författare)
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Implementation and evaluation of tilted foils polarization at REX-ISOLDE
- 2012
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Ingår i: Physica Scripta. - 1402-4896 .- 0031-8949. ; T150:T150
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Tidskriftsartikel (refereegranskat)abstract
- The progress within atomic and nuclear physics relies on refining and adding new observables. One of these is the polarization of the nuclear spin, where there is a manifest interest in accessing a wide variety of polarized beams, e. g. at energies suitable for Coulomb excitation and transfer experiments. In particular, exotic nuclei with half-lives considerably less than one second are difficult to produce, but the issues present in traditional methods could be overcome by using the tilted foils technique. Two setups for measuring the degree of polarization of an ion beam after the REX-ISOLDE linear accelerator at CERN are being evaluated. An approach based on Coulomb excitation has been utilized in an experiment and preliminary results will be presented. Furthermore, a beta-NMR setup is currently under construction that will take radioactive beams soon.
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| 23. |
- Wang, G.Q., et al.
(författare)
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Zonal flows near marginal stability in drift wave transport
- 2015
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Ingår i: Physica Scripta. - : IOP Publishing. - 1402-4896 .- 0031-8949. ; 90:6, s. Art. no. 065604-
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Tidskriftsartikel (refereegranskat)abstract
- The Dimits nonlinear upshift has for the first time been explained with good quantitative agreement. This was done with the reactive toroidal advanced fluid model. This is also the first time that the Dimits shift has been simulated in a transport code. The upshift of the critical gradient for transport is due to the fluid resonance, enhancing the zonal flow and the finite width is due to detuning of the resonance by the linear growth rate.
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| 24. |
- Ward, Daniel, et al.
(författare)
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Alpha-particle formation and decay rates from Skyrme-HFB wave functions
- 2014
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Ingår i: Physica Scripta. - : IOP Publishing. - 0031-8949 .- 1402-4896. ; 89:5
-
Tidskriftsartikel (refereegranskat)abstract
- alpha decay is treated microscopically, where the unstable mother nucleus and residual daughter nucleus are described using Hartree-Fock-Bogoliubov (HFB) wave functions, obtained with the Skyrme effective interaction. From these wave functions the amplitude for forming alpha particles in the mother nucleus is computed. Two different Skyrme parametrizations with different pairing properties are compared, and we find good agreement with experiment for relative decay rates in both cases. The absolute values of the decay rates are underestimated.
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| 25. |
- Weiland, Jan, 1944
(författare)
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Thermal instabilities in drift wave turbulence
- 2015
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Ingår i: Physica Scripta. - : IOP Publishing. - 1402-4896 .- 0031-8949. ; 90:8, s. Art. no. 088009-
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Tidskriftsartikel (refereegranskat)abstract
- The difference between simple drift waves driven by the density gradient and thermal instabilities driven by the temperature gradient is discussed. It is shown that thermal instabilities basically are of a kinetic nature although they can also be accurately described by an advanced fluid model.
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