120781216
Minimono: An ultracompact permanent magnet ion source for singly charged ions
Minimono is a 2.45 GHz electron cyclotron resonance ion source for singly charged ions which uses only permanent magnets. Measurements of ionization efficiencies, maximum currents extracted, and emittances for H+, 3,4He+, N+, Ne+, Ar+, Kr+, S+, and Si+ were carried out. In the case of buckminster fullerenes, C60+, C602+, and C603+ ions were extracted. The results obtained, the general mechanical simplicity of this ion source, and its low cost make this source attractive for the production of stable and radioactive ions.
6513116
Differential cross section for neutron scattering from Bi209 at 37 MeV and the weak particle-core coupling
Differential scattering cross-section data have been measured at 43 angles from 11 deg. to 160 deg. for 37-MeV neutrons incident on {sup 209}Bi. The primary motivation for the measurements is to address the scarcity of neutron scattering data above 30 MeV and to improve the accuracy of optical-model predictions at medium neutron energies. The high-statistics measurements were conducted at the China Institute of Atomic Energy using the {sup 3}H(d,n){sup 4}He reaction as the neutron source, a pulsed deuteron beam, and time-of-flight (TOF) techniques. Within the resolution of the TOF spectrometer, the measurements included inelastic scattering components. The sum of elastic and inelastic scattering cross sections was computed in joint optical-model and distorted-wave Born approximation calculations under the assumption of the weak particle-core coupling. The results challenge predictions from well-established spherical optical potentials. Good agreement between data and calculations is achieved at 37 MeV provided that the balance between surface and volume absorption in a recent successful model [A. J. Koning and J. P. Delaroche, Nucl. Phys. A 713, 231 (2003)] is modified, thus suggesting the need for global optical-model improvements at medium neutron energies.
121772448
Challenging nuclear structure models through a microscopic description of proton inelastic scattering off 208Pb
A fully microscopic calculation of inelastic proton scattering off {sup 208}Pb is presented, and compared to experimental scattering data for incident proton energies between 65 and 201 MeV. By constructing the nucleon-nucleus interaction through the folding of nuclear structure information with a reliable nucleon-nucleon effective interaction that has no adjusted parameter, a consistent framework is built, for probing the influence of different descriptions of nuclear structure on nucleon inelastic scattering predictions. The absence of phenomenological normalization in this framework guarantees a unique and unambiguous interpretation of our calculations in terms of quality of the underlying nuclear structure description: a feature that had been reserved, until recently, to the electron probe. This tool is used to investigate the effect of long range correlations embedded in excited states, on calculated inelastic observables, demonstrating the sensitivity of nucleon scattering predictions to details of the nuclear structure.
119249498
Particle-particle random-phase approximation applied to beryllium isotopes
This paper is dedicated to the study of even-even {sup 8-14}Be isotopes, which uses the particle-particle random-phase approximation that accounts for two-body correlations in the core nucleus. A better description of energies and two-particle amplitudes is obtained in comparison with models that assume a neutron closed-shell (or subshell) core. A Woods-Saxon potential corrected by a phenomenological particle-vibration coupling term has been used for the neutron-core interaction and the D1S Gogny force for the neutron-neutron interaction. Calculated ground-state properties as well as excited-state ones are discussed and are compared to experimental data. In particular, results suggest the same 2s{sub 1/2}-1p{sub 1/2} shell inversion in {sup 13}Be as in {sup 11}Be.
117160842
Microscopic description of elastic and inelastic proton scattering from 208pb
Information on the equation of state (EOS) of neutron matter may be gained from studies of 208Pb. Descriptions of 208Pb require credible models of structure, taking particular note also of the spectrum. Such may be tested by analyses of scattering data. Herein, we report on such analyses using an RPA model for 208Pb in a folding model of the scattering. No a posteriori adjustment of parameters are needed to obtain excellent agreement with data. 
From those analyses, the skin thickness of 208Pb is constrained to lie in the range 0.13-0.17 fm.
121877783
Production of metallic ions with an ECRIS at GANIL
A summary of recent and future developments in metallic ion production with an electron cyclotron resonance ion source (ECRIS) at GANIL is presented. Multicharged metallic ions are routinely produced with an ECRIS (ECR4 14 GHz) and accelerated for nuclear and atomic physics experiments. We present the various methods which have been used to generate these multicharged metallic ions. The accelerator requires stable beams for periods of weeks. The results obtained recently by direct ion plasma sputtering of Ni, Nb, and U samples are remarkable and stable beams from these metals have been delivered continuously for weeks. A pulsed EXCIMER laser, injecting a beam axially through the extraction hole of the ECRIS, has been tested for ablation on a rotating uranium target for uranium beam production. The metal ions from volatile compounds technique using volatile compounds has been also tested with ferrocene [Fe(C5H5)2] to produce multicharged Fe ions. We plan to install a third high voltage platform using an EC...
118728019
Spin Foam Models for Quantum Gravity and semi-classical limit
The spinfoam framework is a proposal for a regularized path integral for quantum gravity. Spinfoams define quantum space-time structures describing the evolution in time of the spin network states for quantum geometry derived from Loop Quantum Gravity (LQG). The construction of this covariant approach is based on the formulation of General Relativity as a topological theory plus the so-called simplicity constraints which introduce local degrees of freedom. The simplicity constraints are essential in turning the non-physical topological theory into 4d gravity. In this PhD manuscript, an original way to impose the simplicity constraints in 4d Euclidean gravity using harmonic oscillators is proposed and new coherent states, solutions of the constraints, are given. Moreover, a consistent spinfoam model for quantum gravity has to be connected to LQG and must have the right semi-classical limit. An explicit map between the spin network states of LQG and the boundary states of spinfoam models is given connecting the canonical and the covariant approaches. Finally, new techniques to compute semiclassical asymptotic expressions for the transition amplitudes of 3d quantum gravity and to extract semi-classical information from a spinfoam model are introduced. Explicit computations based on approximation methods and on the use of recurrence relations on spinfoam amplitudes have been performed. The results are relevant to derive quantum corrections to the dynamics of the gravitational field.
119164220
Lifting SU(2) spin networks to projected spin networks
Projected spin network states are the canonical basis of quantum states of geometry for the recent EPRL-FK spinfoam models for quantum gravity introduced by Engle-Pereira-Rovelli-Livine and Freidel-Krasnov. They are functionals of both the Lorentz connection and the time-normal field. We analyze in detail the map from these projected spin networks to the standard SU(2) spin networks of loop quantum gravity. We show that this map is not one to one and that the corresponding ambiguity is parameterized by the Immirzi parameter. We conclude with a comparison of the scalar products between projected spin networks and SU(2) spin network states.
56019250
Tensor Operators in Loop Quantum Gravity
We discuss how the quantization of the spinorial formalism for Loop Quantum Gravity naturally leads to the notion of tensor operators. These objects encode the natural structure to discuss observables associated to the intertwiner space. They allow in particular to deal with any type of gauge group, classical or quantum. After reviewing the standard case of \(\mathrm {SU}(2)\), we focus on the specific example of \({{\fancyscript{U}}_{q}({\mathfrak su}(2))}\) and illustrate how dealing with a quantum group leads to the notion of quantum curved geometry.
119171972
Holomorphic simplicity constraints for 4D spinfoam models
Within the framework of spinfoam models, we revisit the simplicity constraints reducing topological BF theory to 4D Riemannian gravity. We use the reformulation of SU(2) intertwiners and spin networks in terms of spinors, which has come out from both the recently developed U(N) framework for SU(2) intertwiners and the twisted geometry approach to spin networks and spinfoam boundary states. Using these tools, we are able to perform a holomorphic/anti-holomorphic splitting of the simplicity constraints and define a new set of holomorphic simplicity constraints, which are equivalent to the standard ones at the classical level and which can be imposed strongly on intertwiners at the quantum level. We then show how to solve these new holomorphic simplicity constraints using coherent intertwiner states. We further define the corresponding coherent spin network functionals and introduce a new spinfoam model for 4D Riemannian gravity based on these holomorphic simplicity constraints and whose amplitudes are defined from the evaluation of the new coherent spin networks.
119459711
Revisiting the simplicity constraints and coherent intertwiners
In the context of loop quantum gravity and spinfoam models, the simplicity constraints are essential in that they allow one to write general relativity as a constrained topological BF theory. In this work, we apply the recently developed U(N) framework for SU(2) intertwiners to the issue of imposing the simplicity constraints to spin network states. More particularly, we focus on solving on individual intertwiners in the 4D Euclidean theory. We review the standard way of solving the simplicity constraints using coherent intertwiners and we explain how these fit within the U(N) framework. Then we show how these constraints can be written as a closed algebra and we propose a set of U(N) coherent states that solves all the simplicity constraints weakly for an arbitrary Immirzi parameter.