Experimental Evidence of Beam Trapping with one-third and one-fifth Resonance Crossing

Beam trapping in stable islands of the horizontal phase space generated by non-linear magnetic fields is realized by means of a given tune variation so to cross a resonance of order n. Whenever the resonance is stable, n + 1 beamlets are created whereas if the resonance is unstable, the beam is split in n parts. Experiments at the CERN Proton Synchrotron showed protons trapped in stable islands while crossing the one-third and one-fifth resonance with the creation of 3 and 6 stable beamlets, respectively. The results are presented and discussed

Adiabaticity and Reversibility Studies for Beam Splitting using Stable Resonances

At the CERN Proton Synchrotron, a series of beam experiments proved beam splitting by crossing the one-fourth resonance. Depending on the speed at which the horizontal resonance is crossed, the splitting process is more or less adiabatic, and a different fraction of the initial beam is trapped in the islands. Experiments prove that when the trapping process is reversed and the islands merged together, the final distribution features thick tails. The beam population in such tails is correlated to the speed of the resonance crossing and to the fraction of the beam trapped in the stable islands. Experiments and possible theoretical explanations are discussed

Progress in the Beam preparation for the Multi-Turn Extraction at the CERN Proton Synchrotron

A new type of extraction based on beam trapping inside stable islands in the horizontal phase space will become operational during 2008 at the CERN Proton Synchrotron. A series of beam experiments was carried out to prove lossless capture with high intensity and multi-bunched beams, up to $1.5 × 10^{13}$ protons per pulse, in preparation of the extraction commissioning. These fundamental steps for the new Multi-turn Extraction are presented and discussed in details

Chromaticity dependence of the transverse effective impedance in the CERN Proton Synchrotron

The current knowledge of the transverse beam coupling impedance of the CERN Proton Synchrotron (PS) has been established with beam-based measurements at different energies. The transverse coherent tune shift as a function of the beam intensity has been measured in order to evaluate the total effective imaginary part of the transverse impedance in the accelerator at the energies of 7, 13 and 25 GeV. Measurements have been performed changing the vertical chromaticity for each vertical tune scan with intensity. The data analysis revealed an increase of impedance with chromaticity for all the considered energies. The transverse impedance can be compared with the previously evaluated theoretical impedance budget taking into account the individual contribution of several machine devices

Il filtro di Wiener per la determinazione della superficie dinamica media degli oceani

Una superficie dinamica media degli oceani (Mean Dynamic Ocean Topography) globale è stata calcolata usando esclusivamente dati da satellite: il geoide è ottenuto da un modello di gravità basato sui dati del satellite GOCE, mentre la superficie media del mare (Mean Sea Surface) è ottenuta usando solo misure altimetriche. Poiché il modello di gravità considerato (TIMR5) è disponibile fino a grado e ordine 280, la corrispondente MDT deve essere filtrata consistentemente. In particolare la MDT viene rappresentata in serie di armoniche sferiche e successivamente filtrata applicando il principio di minimizzazione di Wiener. La rappresentazione in armoniche sferiche richiede di avere valori su tutta la superficie terrestre e non soltanto sulla superficie degli oceani, è quindi necessario coprire la superficie dei continenti con valori fittizi. Per questo scopo è stata adottata una procedura di riempimento tale da garantire che il segnale globale abbia la stessa covarianza del segnale solo sugli oceani. Infine, propagando l’errore del geoide e della MSS, sono state calcolate le matrici di varianza-covarianza della MDT stessa e delle velocità geostrofiche da questa derivate

Physics Potential of Very Intense Conventional Neutrino Beams

The physics potential of high intensity conventional beams is explored. We consider a low energy super beam which could be produced by a proposed new accelerator at CERN, the Super Proton Linac. Water Cherenkov and liquid oil scintillator detectors are studied as possible candidates for a neutrino oscillation experiment which could improve our current knowledge of the atmospheric parameters and measure or severely constrain the parameter connecting the atmospheric and solar realms. It is also shown that a very large water detector could eventually observe leptonic CP violation. The reach of such an experiment to the neutrino mixing parameters would lie in-between the next generation of neutrino experiments (MINOS, OPERA, etc) and a future neutrino factory.Comment: Talk given at the Venice Conference on Neutrino Telescopes, Venice, March, 200

Phase Rotation, Cooling And Acceleration Of Muon Beams: A Comparison Of Different Approaches

Experimental and theoretical activities are underway at CERN with the aim of examining the feasibility of a very-high-flux neutrino source. In the present scheme, a high-power proton beam (some 4 MW) bombards a target where pions are produced. The pions are collected and decay to muons under controlled optical condition. The muons are cooled and accelerated to a final energy of 50 GeV before being injected into a decay ring where they decay under well-defined conditions of energy and emittance. We present the most challenging parts of the whole scenario, the muon capture, the ionisation-cooling and the first stage of the muon acceleration. Different schemes, their performance and the technical challenges are compared.Comment: LINAC 2000 CONFERENCE, paper ID No. THC1