[en] We investigate the out of equilibrium dynamics of global chiral supersymmetry at finite energy density. We concentrate on two specific models. The first is the massive Wess-Zumino model which we study in a self-consistent one-loop approximation. We find that for energy densities above a certain threshold, the fields are driven dynamically to a point in field space at which the fermionic component of the superfield is massless. The state, however, is found to be unstable, indicating a breakdown of the one-loop approximation. To investigate further, we consider an O(N) massive chiral model which is solved exactly in the large N limit. For sufficiently high energy densities, we find that for late times the fields reach a nonperturbative minimum of the effective potential degenerate with the perturbative minimum. This minimum is a true attractor for O(N) invariant states at high energy densities, and this provides a mechanism for determining which of the otherwise degenerate vacua is chosen by the dynamics. The final state for large energy density is a cloud of massless particles (both bosons and fermions) around this new nonperturbative supersymmetric minimum. By introducing boson masses which softly break the supersymmetry, we demonstrate a see-saw mechanism for generating small fermion masses. We discuss some of the cosmological implications of our results

[en] We have studied the fragmentation of thymidine and deoxyadenosine induced by slow multiply charged ions. The measured mass spectra specify as an important reaction channel the separation of the molecules into their basic and osidic parts, combined with some structural modifications. In particular for higher projectile charges singly and doubly charged small-size fragments (m<100) are produced, but also the formation of large molecules (modified dimers or trimers) occurs in the sputtering process. The sputtering yield increases with the charge state, the grazing angle as well as the kinetic energy of the projectile

[en] For the needs of future heavy ions accelerators, electron cyclotron resonance ion sources (ECRIS) should be able to deliver intense beams of multiply charged ions. The 1 emA level intensity has been reached by ECRIS for medium charge states (e.g. O⁶⁺, Ar⁸⁺). However, thanks to a better optimization of the ionic lifetimes inside the ion source, high charge states intensities are also been improved. After a presentation of some scaling laws governing the ECRIS behavior, different ion sources will be shown: new compact all permanent magnet source shown, upgrade of the CAPRICE type source and a fully superconducting source

[en] The accelerated expansion of the Universe measured by high redshift Type Ia supernova observations is explained using the nonequilibrium dynamics of naturally soft boson fields. Spinodal instabilities inevitably present in such systems yield a very attractive mechanism for arriving at the required equation of state at late times, while satisfying all the known constraints on models of quintessence. (c) 2000 The American Physical Society

[en] We analyze the dynamics of spinodal decomposition in inflationary cosmology using the closed time path formalism of out of equilibrium quantum field theory combined with the non-perturbative Hartree approximation. In addition to a general analysis, we compute the detailed evolution of two inflationary models of particular importance: λΦ⁴ new inflation and natural inflation. We compute the metric fluctuations resulting from inflationary phase transitions in the slow roll approximation, showing that there exists a regime for which quantum fluctuations of the inflaton field result in a significant deviation in the predictions of the spectrum of primordial density perturbations from standard results. We provide case examples for which a blue tilt to the power spectrum (i.e. n_s>1) results from the evolution of a single inflaton field, and demonstrate that field fluctuations may result in a scalar amplitude of fluctuations significantly below standard predictions, resulting in a slight alleviation of the inflationary fine-tuning problem. We show explicitly that the metric perturbation spectrum resulting from inflation depends upon the state at the outset of the inflationary phase. (c) 2000 The American Physical Society

[en] Out-of-equilibrium, non-perturbative, quantum effects significantly modify the standard picture of inflation in a wide class of models including new, natural, and hybrid inflation. We find that the quantum evolution of a single real inflaton field may be modeled by a classical theory of two homogeneous scalar fields. We briefly discuss the important observational consequences that are expected to result. copyright 1999 The American Physical Society

[en] Grenoble Test Source (GTS) is a room temperature electron cyclotron resonance ion source whose purpose is to deepen the knowledge of this type of device. GTS was designed according to magnetic scaling laws determined with the SERSE source [Hitz et al., Rev. Sci. Instrum. 73, 509 (2002); Gammino et al., ibid. 72, 4090 (2001)] while keeping enough flexibility in terms of magnetic confinement and rf heating to determine best conditions for the production of intense beams of any charge state. First results were presented 1 year ago [Hitz et al., 8th European Particle Accelerator Conference, 2002; 15th International Workshop on ECR Ion Sources, 2002]. Since then, some improvements have been performed mostly in the magnetic confinement, beam extraction and analysis. Updated ion beam intensities are presented: e.g., 0.5 mA of Ar¹¹⁺ at 18 GHz, 20 μA of Ar¹⁶⁺ and 1.8 μA of Ar¹⁷⁺ when GTS is operated at 14.5 GHz. On the other hand, charge coupled device imagers have been installed to diagnose and monitor the ion beam and some beam images are shown

[en] We consider an O(N) model coupled self-consistently to gravity in the semiclassical approximation, where the field is subject to open-quotes new inflationclose quotes type initial conditions. We study the dynamics self-consistently and non-perturbatively with non-equilibrium field theory methods in the large N limit. We find that spinodal instabilities drive the growth of non-perturbatively large quantum fluctuations which shut off the inflationary growth of the scale factor. We find that a very specific combination of these large fluctuations plus the inflaton zero mode assemble into a new effective field. This new field behaves classically and it is the object which actually rolls down. We show how this reinterpretation saves the standard picture of how metric perturbations are generated during inflation and that the spinodal growth of fluctuations dominates the time dependence of the Bardeen variable for superhorizon modes during inflation. We compute the amplitude and index for the spectrum of scalar density and tensor perturbations and argue that in all models of this type the spinodal instabilities are responsible for a open-quotes redclose quotes spectrum of primordial scalar density perturbations. A criterion for the validity of these models is provided and contact with the reconstruction program is established validating some of the results within a non-perturbative framework. The decoherence aspects and the quantum to classical transition through inflation are studied in detail by following the full evolution of the density matrix and relating the classicality of cosmological perturbations to that of long-wavelength matter fluctuations. copyright 1998 The American Physical Society

[en] We study the nonlinear dynamics of quantum fields in matter- and radiation-dominated universes, using the nonequilibrium field theory approach combined with the nonperturbative Hartree and the large N approximations. We examine the phenomenon of explosive particle production due to spinodal instabilities and parametric amplification in expanding universes with and without symmetry breaking. For a variety of initial conditions, we compute the evolution of the inflaton, its quantum fluctuations, and the equation of state. We find explosive growth of quantum fluctuations, although particle production is somewhat sensitive to the expansion of the universe. In the large N limit for symmetry-breaking scenarios, we determine generic late time solutions for any flat Friedmann-Robertson-Walker (FRW) cosmology. We also present a complete and numerically implementable renormalization scheme for the equation of motion and the energy momentum tensor in flat FRW cosmologies. In this scheme the renormalization constants are independent of time and of the initial conditions. copyright 1997 The American Physical Society

[en] This paper addresses foams which are known as non-stochastic foams, lattice structures, or repeating open cell structure foams. The paper reports on preliminary research involving the design and fabrication of non-stochastic Ti-6Al-4V alloy structures using the electron beam melting (EBM) process. Non-stochastic structures of different cell sizes and densities were investigated. The structures were tested in compression and bending, and the results were compared to results from finite element analysis simulations. It was shown that the build angle and the build orientation affect the properties of the lattice structures. The average compressive strength of the lattice structures with a 10% relative density was 10 MPa, the flexural modulus was 200 MPa and the strength to density ration was 17. All the specimens were fabricated on the EBM A2 machine using a melt speed of 180 mm/s and a beam current of 2 mA. Future applications and FEA modeling were discussed in the paper