Search results for "Linear accelerator"
showing 10 items of 20 documents
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.
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…
High-Gradient issues in S-band RF Acceleration Structure for Hadrontherapy accelerators and Radio Frequency Quadrupoles
2020
La investigación de estructuras de microondas de alto gradiente en aceleradores lineales es un tema clave en instalaciones de física de altas energías, y en particular en sistemas de física médica basados en hadronterapia. Esta Tesis Doctoral se centra en el estudio de los problemas que surgen al emplear sistemas de alto gradiente en estructuras aceleradoras de radiofrecuencia no superconductoras. Uno de los efectos que aparecen durante la operación de alta potencia en estos sistemas son los arcos de vacío de RF, llamados breakdown. Esto ocurre debido a los altos campos electromagnéticos de RF que aparecen en las estructuras aceleradoras. Tales eventos tienen un impacto en el rendimiento de…
Precision luminosity measurements at LHCb
2014
Measuring cross-sections at the LHC requires the luminosity to be determined accurately at each centre-of-mass energy $\sqrt{s}$. In this paper results are reported from the luminosity calibrations carried out at the LHC interaction point 8 with the LHCb detector for $\sqrt{s}$ = 2.76, 7 and 8 TeV (proton-proton collisions) and for $\sqrt{s_{NN}}$ = 5 TeV (proton-lead collisions). Both the "van der Meer scan" and "beam-gas imaging" luminosity calibration methods were employed. It is observed that the beam density profile cannot always be described by a function that is factorizable in the two transverse coordinates. The introduction of a two-dimensional description of the beams improves sig…
Investigation of ISIS and Brookhaven National Laboratory ion source electrodes after extended operation.
2012
Linac4 accelerator of Centre Européen de Recherches Nucléaires is under construction and a RFdriven H− ion source is being developed. The beam current requirement for Linac4 is very challenging: 80 mA must be provided. Cesiated plasma discharge ion sources such as Penning or magnetron sources are also potential candidates. Accelerator ion sources must achieve typical reliability figures of 95% and above. Investigating and understanding the underlying mechanisms involved with source failure or ageing is critical when selecting the ion source technology. Plasma discharge driven surface ion sources rely on molybdenum cathodes. Deformation of the cathode surfaces is visible after extended opera…
Monte Carlo simulations of high-energy electron beams : model validation and dose calculations
2017
Komponenttisäteilytykseen valjastetusta Varian Clinac 2100 C/D -lineaarikiihdyttimestä luotiin Monte Carlo -menetelmiä hyödyntävä simulaatiomalli. Malli luotiin aineen ja säteilyn vuorovaikutuksien laskennalliseen mallintamiseen tarkoitettua Geant4 -ohjelmointityökalupakettia käyttäen. Mallin kyky ennustaa mittaustuloksia kiihdyttimen tuottamasta 20 MeV:in elektronisuihkusta todennettiin laskettuja ja mitattuja tuloksia vertailemalla, ja mallin jatkokehityksen kannalta tärkeimmät toimenpiteet määriteltiin. Lisäksi arvioitiin mallin ennustamaa absorpoitunutta annosta vesi- ja piifantomeissa, sekä laskettiin viitearvo absorpoituneen annoksen ja elektronivuon suhteelle. Lasketut annosprofiilit…
Search for lepton flavor violating decays τ±→l± ω
2008
A search for lepton flavor violating decays of a {tau} to a lighter-mass charged lepton and an {omega} vector meson is performed using 384.1 fb{sup -1} of e{sup +}e{sup -} annihilation data collected with the BABAR detector at the Stanford Linear Accelerator Center PEP-II storage ring. No signal is found, and the upper limits on the branching ratios are determined to be {beta}({tau}{sup {+-}} {yields} e{sup {+-}}{omega}) < 1.1 x 10{sup -7} and {beta}({tau}{sup {+-}} {yields} {mu}{sup {+-}}{omega}) < 1.0 x 10{sup -7} at 90% confidence level.
High-gradient testing of an $S$-band, normal-conducting low phase velocity accelerating structure
2020
A novel high-gradient accelerating structure with low phase velocity, $v/c=0.38$, has been designed, manufactured and high-power tested. The structure was designed and built using the methodology and technology developed for CLIC $100\text{ }\text{ }\mathrm{MV}/\mathrm{m}$ high-gradient accelerating structures, which have speed of light phase velocity, but adapts them to a structure for nonrelativistic particles. The parameters of the structure were optimized for the compact proton therapy linac project, and specifically to 76 MeV energy protons, but the type of structure opens more generally the possibility of compact low phase velocity linacs. The structure operates in S-band, is backward…
Untersuchung der beiden ersten angeregten Zustände des Li6-Kernes durch Elektronenstreuung
1969
Inelastic electron cross sections for Li6 were measured using the facilities at the 300 MeV linear accelerator of the Institut fur Kernphysik in Mainz. The form factor for theC 2 transition to the 2.184 MeV level is given in the region of momentum transfer 0.4 fm−1<q<1.9 fm−1. It was possible to determine the form factor for the 3.562 MeVM 1 transition up toq=1.2 fm−1.
Innovative remotely-controlled bending device for thin silicon and germanium crystals
2020
Steering of negatively charged particle beams below 1 GeV has demonstrated to be possible with thin bent silicon and germanium crystals. A newly designed mechanical holder was used for bending crystals, since it allows a remotely-controlled adjustment of crystal bending and compensation of unwanted torsion. Bent crystals were installed and tested at the MAMI Mainz MIcrotron to achieve steering of 0.855-GeV electrons at different bending radii. We report the description and characterization of the innovative bending device developed at INFN Laboratori Nazionali di Legnaro (LNL).