Charge noise in single-electron transistors and charge qubits may be caused by metallic grains

We report on measurements of low-frequency noise in a single-electron transistor (SET) from a few hertz up to 10 MHz. Measurements were done for different bias and gate voltages, which allow us to separate noise contributions from different noise sources. We find a 1/f noise spectrum with two Lorentzians superimposed. The cut-off frequency of one of the Lorentzians varies systematically with the potential of the SET island. Our data is consistent with two single-charge fluctuators situated close to the tunnel barrier. We suggest that these are due to random charging of aluminum grains, each acting as a single-electron box with tunnel coupling to one of the leads and capacitively coupled to the SET island. We are able to fit the data to our model and extract parameters for the fluctuators

Insights into the copper HiPIMS discharge:deposition rate and ionised flux fraction

The influence of pulse length, working gas pressure, and peak discharge current density on the deposition rate and ionised flux fraction in high power impulse magnetron sputtering discharges of copper is investigated experimentally using a charge-selective (electrically biasable) magnetically shielded quartz crystal microbalance (or ionmeter). The large explored parameter space covers both common process conditions and extreme cases. The measured ionised flux fraction for copper is found to be in the range from ≈10% to 80%, and to increase with increasing peak discharge current density up to a maximum at ≈ 1.25 A cm − 2 , before abruptly falling off at even higher current density values. Low working gas pressure is shown to be beneficial in terms of both ionised flux fraction and deposition rate fraction. For example, decreasing the working gas pressure from 1.0 Pa to 0.5 Pa leads on average to an increase of the ionised flux fraction by ≈ 14 percentage points (pp) and of the deposition rate fraction by ≈ 4 pp taking into account all the investigated pulse lengths.</p

Target ion and neutral spread in high power impulse magnetron sputtering

In magnetron sputtering, only a fraction of the sputtered target material leaving the ionization region is directed toward the substrate. This fraction may be different for ions and neutrals of the target material as the neutrals and ions can exhibit a different spread as they travel from the target surface toward the substrate. This difference can be significant in high power impulse magnetron sputtering (HiPIMS) where a substantial fraction of the sputtered material is known to be ionized. Geometrical factors or transport parameters that account for the loss of produced film-forming species to the chamber walls are needed for experimental characterization and modeling of the magnetron sputtering discharge. Here, we experimentally determine transport parameters for ions and neutral atoms in a HiPIMS discharge with a titanium target for various magnet configurations. Transport parameters are determined to a typical substrate, with the same diameter (100 mm) as the cathode target, and located at a distance 70 mm from the target surface. As the magnet configuration and/or the discharge current are changed, the transport parameter for neutral atoms ζ tn remains roughly the same, while transport parameters for ions ζ ti vary greatly. Furthermore, the relative ion-to-neutral transport factors, ζ ti / ζ tn, that describe the relative deposited fractions of target material ions and neutrals onto the substrate, are determined to be in the range from 0.4 to 1.1

On the electron energy distribution function in the high power impulse magnetron sputtering discharge

We apply the Ionization Region Model (IRM) and the Orsay Boltzmann equation for ELectrons coupled with Ionization and eXcited states kinetics (OBELIX) model to study the electron kinetics of a high power impulse magnetron sputtering (HiPIMS) discharge. In the IRM the bulk (cold) electrons are assumed to exhibit a Maxwellian energy distribution and the secondary (hot) electrons, emitted from the target surface upon ion bombardment, are treated as a high energy tail, while in the OBELIX the electron energy distribution is calculated self-consistently using an isotropic Boltzmann equation. The two models are merged in the sense that the output from the IRM is used as an input for OBELIX. The temporal evolutions of the particle densities are found to agree very well between the two models. Furthermore, a very good agreement is demonstrated between the bi-Maxwellian electron energy distribution assumed by the IRM and the electron energy distribution calculated by the OBELIX model. It can therefore be concluded that assuming a bi-Maxwellian electron energy distribution, constituting a cold bulk electron group and a hot secondary electron group, is a good approximation for modeling the HiPIMS discharge

Faire l’Union. La refondation des parties de droite après les élections de 2002

Un nouveau parti de droite, pour le moment dénommé UMP, a été mis en place entre des deux tours de l'élection présidentielle. Cet article se donne pour objectif d'analyser les enjeux de cette transformation. La genèse de l'UMP permet de saisir dans quelle mesure un parti poli-tique peut être conçu comme la connexion d'un ensemble de systèmes de coopération organisés autour de postes à conquérir. En effet, l'impératif d'unification de la droite française est lié au décalage persistant existant entre les systèmes de coopération législatif et présidentiel. Mais les questions soulevées par cette fusion partisane (l'UMP inclut le RPR, DL et une majeure partie de l'UDF) montrent que cette vision ne peut suffire et que les partis ne sont pas seulement des systèmes de coopération mais aussi des systèmes de production. Dès lors, leurs logiques d'organisation internes pèsent sur ce travail de transformation du social en politique, de la plu-ralité en homogénéité. Dans le cas de l'UMP, il s'agit d'abord de mettre en commun des modes de fonctionnement, en particulier de définir la place et la légitimité accordées respectivement aux adhérents et aux élus, mais aussi d'organiser l'expression de la pluralité idéologique par la mise en place de courants

Evaluation of low-cost computer monitors for the detection of cervical spine injuries in the emergency room: an observer confidence-based study

Background: To compare the diagnostic value of low-cost computer monitors and a Picture Archiving and Communication System (PACS) workstation for the evaluation of cervical spine fractures in the emergency room. Methods: Two groups of readers blinded to the diagnoses (2 radiologists and 3 orthopaedic surgeons) independently assessed–digital radiographs of the cervical spine (anterior–posterior, oblique and trans-oral-dens views). The radiographs of 57 patients who arrived consecutively to the emergency room in 2004 with clinical suspicion of a cervical spine injury were evaluated. The diagnostic values of these radiographs were scored on a 3-point scale (1 = diagnosis not possible/bad image quality, 2 = diagnosis uncertain, 3 = clear diagnosis of fracture or no fracture) on a PACS workstation and on two different liquid crystal display (LCD) personal computer monitors. The images were randomised to avoid memory effects. We used logistic mixed-effects models to determine the possible effects of monitor type on the evaluation of x ray images. To determine the overall effects of monitor type, this variable was used as a fixed effect, and the image number and reader group (radiologist or orthopaedic surgeon) were used as random effects on display quality. Group-specific effects were examined, with the reader group and additional fixed effects as terms. A significance level of 0.05 was established for assessing the contribution of each fixed effect to the model. Results: Overall, the diagnostic score did not differ significantly between standard personal computer monitors and the PACS workstation (both p values were 0.78). Conclusion: Low-cost LCD personal computer monitors may be useful in establishing a diagnosis of cervical spine fractures in the emergency room