Search results for "Accelerators and Storage Rings"
showing 10 items of 55 documents
High Gradient Performance of an S-Band Backward Traveling Wave Accelerating Structure for Medical Hadron Therapy Accelerators
2018
The high-gradient performance of an accelerating structure prototype for a medical proton linac is presented. The structure was designed and built using technology developed by the CLIC collaboration and the target application is the TULIP (Turning Linac for Proton therapy) proposal developed by the TERA foundation. The special feature of this design is to produce gradient of more than 50 MV /m in low-β accelerating structures (v/c=0.38). The structure was tested in an S-band test stand at CERN. During the tests, the structure reached over above 60 MV/m at 1.2 μs pulse length and breakdown rate of about 5x10⁻⁶ bpp. The results presented include ultimate performance, long term behaviour and …
Direct measurement of resonance driving terms in the super proton synchrotron (SPS) of cern using beam position monitors
2003
El objetivo principal de esta tesis consiste en desarrollar un metodo para medir los terminos resonantes del Hamiltoniano de un acelerador mediante la transfomada de Fourier de la posicion del haz vuelta tras vuelta. Dos aspectos fundamentales de este metodo de medida son: el efecto de la decoherencia del haz en el espectro de Fourier y la variacion longitudinal de estos terminos resonantes. Ambos se estudian analiticamente y mediante simulaciones numericas. Con el fin de probar la validez de esta tecnica se realizaron experimentos en dos aceleradores de hadrones: el SPS del CERN y el RHIC del BNL. Por ultimo se estudia como utilizar dipolos AC para que esta tecnica no sea destructiva
Present status and first results of the final focus beam line at the KEK Accelerator Test Facility
2011
ATF2 is a final-focus test beam line which aims to focus the low emittance beam from the ATF damping ring to a vertical size of about 37 nm and to demonstrate nanometer level beam stability. Several advanced beam diagnostics and feedback tools are used. In December 2008, construction and installation were completed and beam commissioning started, supported by an international team of Asian, European, and U.S. scientists. The present status and first results are described.
New exotic beams from the SPIRAL 1 upgrade
2018
Since 2001, the SPIRAL 1 facility has been one of the pioneering facilities in ISOL techniques for reaccelerating radioactive ion beams: the fragmentation of the heavy ion beams of GANIL on graphite targets and subsequent ionization in the Nanogan ECR ion source has permitted to deliver beams of gaseous elements (He, N, O, F, Ne, Ar, Kr) to numerous experiments. Thanks to the CIME cyclotron, energies up to 20 AMeV could be obtained. In 2014, the facility was stopped to undertake a major upgrade, with the aim to extend the production capabilities of SPIRAL 1 to a number of new elements. This upgrade, which is presently under commissioning, consists in the integration of an ECR booster in the…
Simulations and measurements of beam loss patterns at the CERN Large Hadron Collider
2014
The CERN Large Hadron Collider (LHC) is designed to collide proton beams of unprecedented energy, in order to extend the frontiers of high-energy particle physics. During the first very successful running period in 2010-2013, the LHC was routinely storing protons at 3.5-4 TeV with a total beam energy of up to 146 MJ, and even higher stored energies are foreseen in the future. This puts extraordinary demands on the control of beam losses. An uncontrolled loss of even a tiny fraction of the beam could cause a superconducting magnet to undergo a transition into a normal-conducting state, or in the worst case cause material damage. Hence a multistage collimation system has been installed in ord…
UFOs in the LHC: Observations, studies and extrapolations
2012
Unidentified falling objects (UFOs) are potentially a major luminosity limitation for nominal LHC operation. They are presumably micrometer sized dust particles which lead to fast beam losses when they interact with the beam. With large-scale increases and optimizations of the beam loss monitor (BLM) thresholds, their impact on LHC availability was mitigated from mid 2011 onwards. For higher beam energy and lower magnet quench limits, the problem is expected to be considerably worse, though. In 2011/12, the diagnostics for UFO events were significantly improved: dedicated experiments and measurements in the LHC and in the laboratory were made and complemented by FLUKA simulations and theore…
The n_TOF facility: Neutron beams for challenging future measurements at CERN
2016
The CERN n TOF neutron beam facility is characterized by a very high instantaneous neutron flux, excellent TOF resolution at the 185 m long flight path (EAR-1), low intrinsic background and coverage of a wide range of neutron energies, from thermal to a few GeV. These characteristics provide a unique possibility to perform high-accuracy measurements of neutron-induced reaction cross-sections and angular distributions of interest for fundamental and applied Nuclear Physics. Since 2001, the n TOF Collaboration has collected a wealth of high quality nuclear data relevant for nuclear astrophysics, nuclear reactor technology, nuclear medicine, etc. The overall efficiency of the experimental prog…
First attempt of the measurement of the beam polarization at an accelerator with the optical electron polarimeter POLO
2005
The conventional methods for measuring the polarization of electron beams are either time consuming, invasive or accurate only to a few percent. We developped a method to measure electron beam polarization by observing the light emitted by argon atoms following their excitation by the impact of polarized electrons. The degree of circular polarization of the emitted fluorescence is directly related to the electron polarization. We tested the polarimeter on a test GaAs source available at the MAMI electron accelerator in Mainz, Germany. The polarimeter determines the polarization of a 50 keV electron beam decelerated to a few eV and interacting with an effusive argon gas jet. The resulting de…
Optimization of the Electron Emission From Carbon Nanotubes for Electron Cooling in ELENA
2021
Electron cooling is a process that guarantees beam quality in low energy antimatter facilities. In ELENA the electron cooler allows to reduce the emittance blow-up of the antiproton beam, thus delivering highly focused and bright beams at the unprecedented low energy of 100 keV to the experiments. In order to have a "cold" beam at such low energy, the electron gun of the cooler must emit a monoenergetic and relatively intense electron beam. Simulations have shown that efficient cooling can be achieved with a 5 mA electron beam having transverse energy spread of less than 100 meV and longitudinal energy spread of about 1 meV. A thermionic gun is currently used in operation, although it limit…
H$^{-}$ extraction systems for CERN’s Linac4 H$^{-}$ ion source
2018
Linac4 is a 160 MeV linear H accelerator at CERN. It is an essential part of the beam luminosity upgrade of the Large Hadron Collider (LHC) and will be the primary injector into the chain of circular accelerators. It aims at increasing the beam brightness by a factor of 2, when compared to the currently used 50 MeV linear proton accelerator, Linac2. Linac4’s ion source is a cesiated RF-plasma H ion source. Several beam extraction systems were designed for H beams of 45 keV energy, 50 mA intensity and an electron to H ratio smaller than 5. The goal was to extract a beam with an rms-emittance of mm mrad. One of the main challenges in designing an H extraction system is dumping of the co-extra…