A Penning-trap facility for high-precision mass spectrometry based on a novel detection method has been built. This method consists in measuring motional frequencies of singly-charged ions trapped in strong magnetic fields through the fluorescence photons from laser-cooled 40 Ca + ions, to overcome limitations faced in electronic single-ion detection techniques. The key element of this facility is an open-ring Penning trap coupled upstream to a preparation Penning trap similar to those used at Radioactive Ion Beam facilities. Here we present a full characterization of the trap and demonstrate motional frequency measurements of trapped ions stored by applying external radiofrequency fields in resonance with the ions' eigenmotions, in combination with time-of-flight identification. The infrastructure developed to observe the fluorescence photons from 40 Ca + , comprising the 12 laser beams and the optical system to register the image in a high-sensitive CCD sensor, has been proved by taking images of the trapped and cooled 40 Ca + ions. This demonstrates the functionality of the proposed laser-based mass-spectrometry technique, providing a unique platform for precision experiments with implications in different fields of physics.

In this article, the dynamics of an unbalanced two-ion crystal comprising the 'target' and the 'sensor' ions confined in a Penning trap has been studied. First, the low amplitude regime is addressed. In this regime, the overall potential including the Coulomb repulsion between the ions can be considered harmonic and the axial, magnetron and reduced-cyclotron modes split up into the so-called 'stretch' and 'common' modes, that are generalizations of the well-known 'breathing' and 'center-of-mass' motions of a balanced crystal made of two ions. By measuring the frequency modes of the crystal and the sensor ion eigenfrequencies using optical detection, it will be possible to determine the target ion's free-cyclotron frequency. The measurement scheme is described and the non-harmonicity of the Coulomb interaction is discussed since this might cause large systematic effects.I. * mjgutierrez@ugr.es.; This work is part of the PhD thesis of M.J. Gutiérrez. † danielrodriguez@ugr.es

This article discusses two phenomena of linguistic change that are taking place in the Spanish spoken by the Mexican-American community of the United States. It tries to determine whether changes occurring in descriptive discourse, specifically in the opposition ser/estar, and in conditional discourse, specifically in the apodosis of the conditional sentences with present/future reference, occur as manifestations of simplification processes. It also tries to determine the role played by the contact language in these processes of linguistic changes. The data examined show that the acceleration of the two changes in the bilingual community has been the result of processes of linguistic simplification. This strategy, used by the speakers to reduce the cognitive load, has brought about the development of linguistic systems much simpler than the previous ones. The two resulting linguistic systems represent linguistic innovations because the previous systems only had the conservative forms. The present systems have at least two forms that are competing for the same semantic domain, but the innovative forms are very powerful and their imposition seems to be probable.

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