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D. Zimmer,
V. Bagnoud,
B. Ecker,
U. Eisenbarth,
J. Habib,
D. Hochhaus,
D. Javorkova,
S. Kazamias,
T. Kuehl,
D. Ros, D. Ursescu,
B. Zielbauer,
Phelix Team
12/2008: pages 91-98; , ISBN: 0930-8989
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Sophie Kazamias,
Kevin Cassou,
D. Ros,
Fabien Ple,
Gérard Jamelot,
A. Klisnick,
O Lundh,
F Lindau,
A Persson,
C.G Wahlstrom,
Sébastien De Rossi,
Denis Joyeux,
B. Zielbauer, D. Ursescu,
T. Kuhl
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ABSTRACT: We present experimental results from an extensive investigation of a Ni-like Mo x-ray laser pumped in the transient regime and GRIP configuration (GRazing Incidence Pumping). The pump laser is a 10 Hz, 1 J, Ti:sapphire laser system. The main diagnostic is a monochromatic near-field imaging system with a 1.7 micron spatial resolution that shows the soft-x-ray laser source size and position relative to the target surface. Changes of those characteristics are observed for different GRIP angles, varied between 15° and 21° , while keeping all other parameters constant. Intense lasing is observed routinely at 18.9 nm with up to 3 microjoule output energy and stable operation is demonstrated at 10 Hz. We have investigated the role of several pumping parameters, in particular, the relative energy and delay between the long and short pulse. We show that this multiparameter scan leads to a well-defined optimal regime of operation and better understanding of the GRIP configuration. Finally, as the GRIP scheme requires careful tailoring of the plasma conditions to the specific soft-x-ray laser under investigation, we add a prepulse before the plasma producing long pulse to generate large-scale preplasmas. This increases the brightness of the soft-x-ray beam and leads to an almost Gaussian near-field spatial profile.
Physical Review A: Atomic, Molecular and Optical Physics. 01/2008; 77:03381.
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ABSTRACT: The structures, the electromagnetic transitions, and the beta decay strengths of exotic nuclei are investigated within an extended cluster model. We start by deriving an effective nuclear Hamiltonian within the $S_2$ correlation operator. Tensor forces are introduced in a perturbative expansion which includes up to the second order terms. Within this Hamiltonian we calculate the distributions and the radii of A=3,~4 nuclei. For exotic nuclei characterized by n valence protons/neutrons we excite the structure of the closed shell nuclei via mixed modes formed by considering correlations operators of higher order. Good results have been obtained for the calculated transitions and for the beta decay transition probabilities.
08/2007;
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F Lindau,
O Lundh,
A Persson,
K Cassou,
S Kazamias,
D Ros,
F Plé,
G Jamelot,
A Klisnick,
S de Rossi,
D Joyeux,
B Zielbauer, D Ursescu,
T Kühl,
C-G Wahlström
[show abstract]
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ABSTRACT: A soft x-ray laser from Ni-like Mo, pumped in grazing incidence (GRIP), is analyzed with regard to high repetition rate operation. Reliable lasing is obtained, but with significant energy fluctuations attributed mainly to beam pointing jitter from the pump laser. Two modes of operation are compared: continuously moving target and stationary target. With a moving target the soft X-ray output is constant on average, whereas the repeated use of the same target position leads to a pulse energy which increases for several tens of shots. This effect might be caused by improved guiding of the pump laser in the formed groove and the removal, through laser ablation, of the oxide layer on the target surface.
Optics Express 08/2007; 15(15):9486-93. · 3.59 Impact Factor
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K Cassou,
S Kazamias,
D Ros,
F Plé,
G Jamelot,
A Klisnick,
O Lundh,
F Lindau,
A Persson,
C-G Wahlström,
S de Rossi,
D Joyeux,
B Zielbauer, D Ursescu,
T Kühl
[show abstract]
[hide abstract]
ABSTRACT: We report the near-field imaging characterization of a 10 Hz Ni-like 18.9 nm molybdenum soft-x-ray laser pumped in a grazing incidence pumping (GRIP) geometry with a table-top laser driver. We investigate the effect of varying the GRIP angle on the spatial behavior of the soft-x-ray laser source. After multiparameter optimization, we were able to find conditions to generate routinely a high-repetition-rate soft-x-ray laser with an energy level of up to 3 microJ/pulse and to 6x10(17) photons/s/mm2/mrad2/(0.1% bandwidth) average brightness and 1x10(28) photons/s/mm2/mrad2/(0.1% bandwidth) peak brightness.
Optics Letters 02/2007; 32(2):139-41. · 3.40 Impact Factor
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ABSTRACT: The structures and distributions of light nuclei are investigated within a microscopic correlation model. Two particle correlations are responsible for the scattering of model particles either to low momentum- or to high momentum-states. The low momentum states form the model space while the high momentum states are used to calculate the G-matrix. The three and higher order particle correlations do not play a role in the latter calculation especially if the correlations induced by the scattering operator are of sufficient short range. They modify however, via the long tail of the nuclear potential, the Slater determinant of the (A) particles by generating excited Slater's determinants.
01/2007;
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ABSTRACT: Energy spectra and electromagnetic transitions of nuclei are strongly depending from the correlations of the bound nucleons. Two particle correlations are responsible for the scattering of model particles either to low momentum- or to high momentum-states. The low momentum states form the model space while the high momentum states are used to calculate the G-matrix. The three and higher order particle correlations do not play a role in the latter calculation especially if the correlations induced by the scattering operator are of sufficient short range. They modify however, via the long tail of the nuclear potential, the Slater determinant of the A particles by generating excited Slater's determinants. In this work the influence of the correlations on the level structure and ground state distributions of even open shell nuclei is analyzed via the boson dynamic correlation model BDCM. The model is based on the unitary operator $e^S$ ({\it S} is the correlation operator) formalism which in this paper is presented within a non perturbative approximation. The low lying spectrum calculated for $^6$Li reproduce very well the experimental spectrum while for $^6$He a charge radius slightly larger than that obtained within the isotopic-shift (IS) theory has been calculated. Good agreement between theoretical and experimental results has been obtained without the introduction of a genuine three body force.
01/2007;
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ABSTRACT: Significant reduction of the total pumping energy for a transient collisionally excited (TCE) x-ray laser (XRL) was made possible
by using nonnormal main pulse pumping. In the attempt to scale to shorter XRL wavelengths, it is described here a theoretical
investigation of the influence of the pumping pulse parameters on the gain generation in a Ni-like Ag x-ray laser (XRL). The
possibility of gain generation closer to the critical density is shown by the EHYBRID code for a set of optimized parameters,
corresponding to a possible setup at the PHELIX laser facility.
12/2006: pages 269-273;
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ABSTRACT: An extended ray-tracing study of the main pumping pulse (MP) focusing optics was made in order to develop a transient collisionally excited (TCE) x-ray laser (XRL) set-up for sub 10 nm wavelength by using non-normal incidence pumping. The study takes into account limitations determined by the large beam dimensions of the high energy MP. A setup using two off-the-shelf spherical mirrors is proposed, corresponding to a possible realization at the PHELIX laser facility.
12/2006: pages 69-73;
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S. Kazamias,
K. Cassou,
D. Ros,
F. Plé,
G. Jamelot,
A. Klisnick,
O. Lundh,
F. Lindau,
A. Persson,
C.-G. Wahlström,
S. de Rossi,
D. Joyeux,
B. Zielbauer, D. Ursescu,
T. Kühl
[show abstract]
[hide abstract]
ABSTRACT: We present recent results on the extensive investigation of a Ni-like Mo X-ray laser pumped in the transient regime and GRIP
configuration (grazing incidence pumping). The pump laser was the 10 Hz, multiterawatt, Ti:Sa Lund University laser system
in Sweden. The main diagnostic was a monochromatic near-field imaging system with a 1.7 micron spatial resolution. Intense
lasing was observed routinely at 18.9 nm with up to 3 microJoule output energy and stable operation at 10 Hz was demonstrated
in 100-shot sequences. We have investigated the role of several pumping parameters, in particular the relative energy and
delay between the long and short pulse. A preliminary investigation was done on the effect of a low energy prepulse. Finally,
the grazing angle of the pumping pulse was systematically varied between 13 and 21°, while keeping all parameters constant.
We show that this multi-parameter scan leads to a well-defined optimal zone of operation and better understanding of the GRIP
configuration.
12/2006: pages 173-181;
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B. Zielbauer, D. Ursescu,
T. Kühl,
S. Kazamias,
K. Cassou,
D. Ros,
A. Klisnick,
F. Plé,
S. de Rossi,
D. Joyeux,
O. Lundh,
F. Lindau,
A. Persson,
C.-G. Wahlström
[show abstract]
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ABSTRACT: Soft x-ray emission, above 600 eV, from a grazing incidence pumped Ni-like Mo x-ray laser (GRIP-XRL) [1] plasma was investigated.
Using a pinhole camera looking along the target surface, perpendicular to the direction of the XRL emission, spatially-resolved
information was obtained with a resolution which was limited only by the pinhole size of 10 μm. The relative distance from
the target surface to the plasma zone heated by th e picosecond pulse was investigated for different GRIP angles, energy ratios
and delays between the plasma producing and the plasma heating pulses.
12/2006: pages 75-80;
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T. Kühl, D. Ursescu,
V. Bagnoud,
D. Javorkova,
O. Rosmej,
D. Zimmer,
K. Cassou,
S. Kazamias,
A. Klisnick,
D. Ros,
B. Zielbauer,
K. Janulewicz,
P. Nickles,
G. Pert,
P. Neumayer,
J. Dunn
[show abstract]
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ABSTRACT: One of the unique features of the PHELIX laser installation is the combination of the ultra-high intensity laser with the
heavy-ion accelerator facility at GSI and its planned extension FAIR. Due to this combination, PHELIX will allow novel investigations
in the fields of plasma physics, atomic physics, nuclear physics, and accelerator studies. An important issue within the scientific
program is the generation of high quality x-ray laser beams for x-ray laser spectroscopy of highly-charged ions. The long
range perspective is the study of nuclear properties of radioactive isotopes within the FAIR [1] project. A novel single mirror
focusing scheme for the TCE XRL has been successfully implemented by the LIXAM/MBI/GSI collaboration under different pump
geometries. Intense and stable laser operation with Ni-like Zr and Ni-like Ag was demonstrated at pump energies between 2
J and 5 J from the PHELIX pre-amplifier section.
12/2006: pages 427-433;
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ABSTRACT: In this contribution we present calculations performed for interacting electron systems within a non-perturbative formulation of the cluster theory. Extrapolation of the model to describe the time dependence of the interacting systems is feasible and planed. The theory is based on the unitary operator $e^{iS}$ ({\it S} is the correlation operator) formalism which, in this paper, is treated non perturbatively within many-particle correlations. The application of the derived equations to few-body systems is realized in terms of Generalized Linearization Approximations (GLA) and via the Cluster Factorization Theory (CFT). To check the reliability of the model we present two different applications. In the first we evaluate the transitions energies in Helium-, Lithium-, Beryllium-, and Boron-like Oxygen. The calculation aims to a precise determination of the satellite transitions which play an important role in plasma diagnostics. In a second we investigate a non-perturbative method to evaluate the charge radii of the Helium and Lithium isotopes by using the Isotopic Shift theory. We have found that our model leads naturally to components of $e^--e^+$ pair in the two-electron wave functions of the Helium isotopes and three-electron wave functions of the Lithium isotopes. The possible connection of these terms to the QED leading diagrams is postulated. Comment: To be publised in the Canadian Journal of Physics
12/2006;
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ABSTRACT: For a better understanding of the dynamics of exotic nuclei it is of crucial importance to develop a practical microscopic theory easy to be applied to a wide range of masses. Theoretically the basic task consists in formulating an easy solvable theory able to reproduce structures and transitions of known nuclei which should be then used to calculate the sparely known properties of proton- or neutron-rich nuclei. In this paper we start by calculating energies and distributions of A≤4 nuclei within a unitary correlation model restricted to include only two-body correlations. The structure of complex nuclei is then calculated extending the model to include correlation effects of higher order.
Progress in Particle and Nuclear Physics. 12/2006;
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ABSTRACT: To facilitate the use of the extended nuclear shell model (NSM), a Fermi module for calculating some of its basic quantities in the framework of Maple is provided. The Moshinsky brackets, the matrix elements for several central and non-central interactions between nuclear two-particle states as well as their expansion in terms of Talmi integrals are easily given within a symbolic formulation. All of these quantities are available for interactive work.Program summaryTitle of program:FermiCatalogue identifier:ADVOProgram summary URL:http://cpc.cs.qub.ac.uk/summaries/ADVOProgram obtainable from: CPC Program Library, Queen's University of Belfast, N. IrelandLicensing provisions:NoneComputer for which the program is designed and others on which is has been tested:All computers with a licence for the computer algebra package Maple [Maple is a registered trademark of Waterloo Maple Inc., produced by MapleSoft division of Waterloo Maple Inc.]Instalations:GSI-Darmstadt; University of Kassel (Germany)Operating systems or monitors under which the program has beentested: WindowsXP, Linux 2.4Programming language used:Maple 8 and 9.5 from MapleSoft division of Waterloo Maple Inc.Memory required to execute with typical data:30 MBNo. of lines in distributed program including test data etc.:5742No. of bytes in distributed program including test data etc.:288 939Distribution program:tar.gzNature of the physical problem:In order to perform calculations within the nuclear shell model (NSM), a quick and reliable access to the nuclear matrix elements is required. These matrix elements, which arise from various types of forces among the nucleons, can be calculated using Moshinsky's transformation brackets between relative and center-of-mass coordinates [T.A. Brody, M. Moshinsky, Tables of Transformation Brackets, Monografias del Instituto de Fisica, Universidad Nacional Autonoma de Mexico, 1960] and by the proper use of the nuclear states in different coupling notations.Method of solution:Moshinsky's transformation brackets as well as two-nucleon matrix elements are provided within the framework of Maple. The transformation brackets are evaluated recursively for a given number of shells and utilized for the computation of the two-particle matrix elements for different coupling schemes and interactions. Moreover, a simple notation has been introduced to handle the two-particle nuclear states in ll-, LSJ-, and jj-coupling, both in the center-of-well and the relative and center-of-mass coordinates.Restrictions onto the complexity of the problem:The program supports in principle an arbitrary number of shell states with the only limitation given by the computer resources themselves. Typically, the time requirements for the recursive computation of the Moshinsky brackets and matrix elements increase rapidly with the number of the allowed shell states but can be reduced significantly by the pre-calculation of the transformation brackets.Unusual features of the program:Moshinsky brackets are computed and provided in either numeric, algebraic or some symbolic form. In addition, the two-particle matrix elements are calculated for a scalar potential, spin-orbit coupling and tensorial forces, both in floating-point and algebraic notation. All two-particle matrix elements are expressed in terms of the Talmi integrals but can be evaluated also explicitly for several predefined types of the interaction. To simplify the handling of the program, a short but very powerful notation has been introduced which help the user to deal with the two-particle states in various coupling notations. The main commands of the current version of the program are described in detail in Appendix B.Typical running time:The computation of all Moshinsky brackets in floating-point notation, up to ρ=6, takes about 5 s at a 2.26 GHz Intel Pentium IIII processor with 512 MB; in algebraic form, the same computations take about 13 s. Similarly, the computation of these brackets up to ρ=10 requires in numeric and algebraic form about 5 and 15 min, respectively. Once these coefficients have been stored, however, the program replies rather promptly on most further requests.
Computer Physics Communications. 01/2005;
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ABSTRACT: The structure and dynamics of an n-particle system are described with coupled nonlinear Heisenberg's commutator equations where the nonlinear terms are generated by the two-body interaction that excites the reference vacuum via particle-particle and particle-hole excitations. Nonperturbative solutions of the system are obtained with the use of dynamic linearization approximation and cluster transformation coefficients. The dynamic linearization approximation converts the commutator chain into an eigenvalue problem. The cluster coefficients factorize the matrix elements of the (n)-particles or particle-hole systems in terms of the matrix elements of the (n-1)-systems coupled to a particle-particle, particle-hole, and hole-hole boson. Group properties of the particle-particle, particle-hole, and hole-hole permutation groups simplify the calculation of these coefficients. The particle-particle vacuum-excitations generate superconductive diagrams in the dynamics of 3-quarks systems. Applications of the model to fermionic and bosonic systems are discussed. Comment: 13 pages, 5 figures, Wigner Proceedings for Conference Wigner Centenial Pecs, July 8-12, 2002
10/2002;
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S. Kazamias,
K Cassou,
D. Ros,
F Plé,
G. Jamelot,
A. Klisnick,
O Lundh,
F Lindau,
A Persson,
C-G Wahlström,
S de Rossi,
D Joyeux,
B. Zielbauer, D. Ursescu
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ABSTRACT: Nous présentons des résultats récents de laser X collisionnel transitoire pompé en incidence rasante à haut taux de répétition. Ils ont été obtenus à partir du laser de pompe Titane :Saphir 30 TW disponible sur l'installation européenne du LLC à Lund (Suède). Nous avons démontré lors de cette expérience qu'il était possible d'obtenir en routine près de 3 microjoule par impulsion à 18,9 nm avec seulement 1 J d'énergie de pompe infrarouge. Nous avons plus particulièrement étudié l'influence de l'angle de rasance sur cible de l'impulsion laser qui vient pomper le plasma, quelques centaines de picosecondes après la première impulsion responsable de sa création. Un système d'imagerie XUV à haute résolution nous a en effet permis d'obtenir des informations précieuses sur la pupille de sortie du laser X, comme l'énergie totale dans la tache mais aussi la distance d'émission par rapport à la cible, et encore les dimensions horizontale et verticale de la source.
http://dx.doi.org/10.1051/jp4:2006138003.
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ABSTRACT: For a better understanding of the dynamics of complex exotic nuclei it is of crucial importance to develop a practical microscopic theory easy to be applied to a wide range of masses. In this paper we propose to calculate the structure of neutron-rich nuclei within a dynamic model based on the EoM theory.
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ABSTRACT: The effects of the microscopic correlations on the matter and charge radii of light mass nuclei have been investigated within a dynamic model. The polarization diagrams of the theory increase the charge radii, thus giving a signal for the departure from the single particle approximation generally used in the investigation of the charge radii of exotic-nuclei.
pages 435-437;
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Nuclear Physics A. 790:246C-250C.
