Optimum Parameters for Electron Cooling

In modern accumulator/storage rings, electron cooling has become an indispensable tool to obtain high quality ion beams with long lifetimes. Many parameters influence the quality of the cooling process: electron-ion beam alignment, electron beam intensity, the length of the cooling section and the ring lattice parameters. The influence of these parameters on the cooling time was studied experimentally with protons and Pb ions in the LEAR ring in two separate 'machine development' sessions during 1996 and 1997. We present the results of these measurements and compare them to what one expects from conventional electron cooling theor

Electron Cooling Experiments at LEIR

The LEIR electron cooler is the first of a new generation of coolers utilising high-perveance variable-density electron beams for the cooling and accumulation of heavy ion beams. It was commissioned at the end of 2005 and has since been routinely used to provide high brightness Pb ion beams required for future LHC ion runs. High perveance, or intensity, is required to rapidly reduce the phase-space dimensions of a newly injected "hot" beam whilst the variable density helps to efficiently cool particles with large betatron oscillations and at the same time improve the lifetime of the cooled stack. In this report we present the results of recent measurements made to check and to better understand the influence of the electron beam size, intensity and density profile on the cooling performance

Diffraction Radiation Angular Spectral Distributions

In a previous paper we have shown that, when applied to CLIC type beams, diffraction radiation (DR) should provide enough photons in the visible range to allow diagnostics measurements of the particle beam. In the present note we analyze in detail the horizontal and vertical polarization component distributions. Special emphasis is given to the influence of the electron beam r.m.s width and divergence

Gas Electron Multipliers for the Antiproton Decelerator

The new beam profile measurement for the Antiproton Decelerator (AD) at CERN is based on a single Gas Electron Multiplier (GEM) with a 2D readout structure. This detector is very light (~0.4% X0), and measures horizontal and vertical profiles directly in one plane. This overcomes the problems previously encountered with multi-wire proportional chambers for the same purpose, where beam interactions with the detector severely affect the obtained profiles. A prototype was installed and successfully tested in late 2010, with another five detectors now installed in the ASACUSA and AEGIS beam lines. This paper will provide a detailed description of the detector and discuss the results obtained.Comment: Paper presented at DIPAC 2011, Hambur

Beam Diagnostics with Schottky Noise in LEIR

The high density Lead ion beams, needed for LHC, are obtained in the Low Energy Ion Ring (LEIR) at CERN by multi-turn injection followed by electron cooling and stacking. During this injection and stacking phases where the circulating beam is unbunched, diagnostics with Schottky noise are used for probing essential beam parameters, such as tune, momentum spread, emittance and their evolution with time... The hardware facility and first results obtained during the recent commissioning of LEIR are described

Histological features of the distal third metacarpal bone in thoroughbred racehorses, with and without lateral condylar fractures

A detailed histopathological study of the distal third metacarpal bone of Thoroughbred racehorses was undertaken to characterize lesions observed previously on magnetic resonance imaging (MRI). The bones were selected and grouped on the basis of MRI features. Representative sections in different planes were processed for histopathology. All lesions observed in the articular cartilage (AC) and subchondral bone (SCB) were recorded and graded with a scoring system, based partially on the Osteoarthritis Research Society International grading system. The scoring system included the severity of the lesion. Descriptive statistics and linear mixed effects models were performed. A positive correlation was observed between the severity of histopathological changes in the superficial and deeper osteochondral tissues, and between the number of race starts and AC score. Age was not correlated with AC or SCB score. A moderate variation in AC and SCB scores was observed between the groups; however, there were differences within individual bones. Bones with focal palmar necrosis (FPN) showed significant differences in the histological scoring of the AC compared with bones without FPN. Bones with incomplete fractures or larger areas of bone remodelling showed significant differences in SCB pathology when compared with bones with FPN. Haematoidin was detected in areas with excessive SCB and cancellous bone sclerosis and/or irregular bone density. This finding is suggestive of poor blood perfusion in these areas

First Results from the LEIR Ionisation Profile Monitors

The role of the Low Energy Ion Ring, LEIR, is to transform long pulses of lead ions from the Linac 3 to short dense bunches for transfer to the LHC. This is accomplished by the accumulation of up to 4 Linac pulses by electron cooling. In order to non-destructively monitor the cooling performance and determine the accumulated beam characteristics, two prototype ionisation profile monitors have been built and were tested during the LEIR commissioning runs with O4+ and Pb54+ ions in 2006. In this paper we present the results obtained with the prototype monitors, the problems encountered and describe the modifications made for the final design. The modified monitors have been installed on the LEIR machine and are waiting for the next ion run planned in August

Formations en résolution des conflits et facilitation : incidence sur les participants

Résumé: La rétention et le transfert des apprentissages, au coeur de cet essai, ont été mesurés au moyen d'entrevues. Les récits des interviewés de deux formations en résolution des conflits en milieu organisationnel sont analysés à l'aide du modèle conceptuel de Kirkpatrick. Trois niveaux du modèle sont mesurés afin de découvrir l'incidence de ces formations une fois que l'apprenant est retourné au travail et éventuellement se trouve face à un conflit. Les entrevues permettent une évocation de la rétention et de l'utilisation des apprentissages. La triangulation méthodologique assure que les résultats de recherche sont fiables . Ceux-ci démontrent un très faible taux de rétention des cinq jours passés en salle de cours malgré la réaction des apprenants sur le formulaire complété le dernier jour de ces formations qui fait foi d 'un taux de satisfaction très élevé. Les résultats portant sur l'utilisation conforme aux enseignements sont également faibles. Des insuffisances sont relevées et jaillissent principalement des récits des interviewés. Des commentaires, suggestions et annexes concernant les nombreuses notions de ces formations sont également élaborées. ||Abstract: Learning recall and transfer, at the heart of this essay, have been measured through interviews. lnterviewee's narratives on two separate organizational conflict resolution workshops are analyzed using the Kirkpatrick's conceptual model. The model 's three first levels are measured to determine the impacts of these workshops once the learner returns to work and eventually faces a conflict situation. Interviews are used to measure the recall and use of the learning. A methodological triangulation ensures that the results are valid. This methodology shows a very weak retention level of the five days classroom workshops even though the learners' reactions, offered through the feedback forms completed on the workshops ' last day present, a very high satisfaction level. Results regarding the use of the learning is (sic) also weak. lnsufficiencies are noted and highlighted mainly from the interviewee 's stories. Comments, suggestions and appendixes regarding the workshop numerous concepts are also presented

Evaluating the Effects of Colour in LineSets

There are a number of graphical choices to be made when drawing LineSets; one of these choices is colour. This paper identifies how colour (hue, value, or monochrome) should be applied to LineSets drawn on networks