In a fixed-field alternating-gradient (FFAG) accelerator, eliminating pulsed magnet operation per... more In a fixed-field alternating-gradient (FFAG) accelerator, eliminating pulsed magnet operation permits rapid acceleration to synchrotron energies, but with a much higher beam-pulse repetition rate. Conceived in the 1950s, FFAGs are enjoying renewed interest, fuelled by the need to rapidly accelerate unstable muons for future high-energy physics colliders. Until now a ‘scaling’ principle has been applied to avoid beam blow-up and loss. Removing this restriction produces a new breed of FFAG, a non-scaling variant, allowing powerful advances in machine characteristics. We report on the first non-scaling FFAG, in which orbits are compacted to within 10 mm in radius over an electron momentum range of 12–18 MeV/c. In this strictly linear-gradient FFAG, unstable beam regions are crossed, but acceleration via a novel serpentine channel is so rapid that no significant beam disruption is observed. This result has significant implications for future particle accelerators, particularly muon and high-intensity proton accelerators.
The CERN PC-based ISOLDE control system has been installed at the SRS electron storage ring at Da... more The CERN PC-based ISOLDE control system has been installed at the SRS electron storage ring at Daresbury Laboratory. The use of Windows NT for the control consoles together with PC and VME front-end computers running under several operating systems has resulted in a flexible and reliable system for accelerator control. The implementation and philosophy of control application programs, based around a suite of Microsoft Visual Basic and Excel programs, is described. In particular, the use of Excel to provide adaptable programs online allows rapid generation of new control functions; orbit correction and servoing at the application level are described as examples of this
4GLS is a suite of accelerator-based light sources planned to provide state-of-the-art radiation ... more 4GLS is a suite of accelerator-based light sources planned to provide state-of-the-art radiation in the low energy photon regime. Superconducting energy recovery linac (ERL) technology will be utilised in combination with a variety of free electron lasers (IR to XUV), undulators and bending magnets. The 4GLS undulators will generate spontaneous high flux, high brightness radiation, of variable polarisation from 3 - 800 eV, optimised in the lower harmonics up to about 200 eV. Viable radiation at energies up to several keV may be provided from multipole wiggler magnet radiation. The ERL technology of 4GLS will allow shorter bunches and higher peak photon fluxes than possible from storage ring sources. It will also give users the added bonuses of pulse structure flexibility and effectively an infinite beam lifetime. VUV and XUV FELs will be used to generate short pulses (in the fs regime) of extreme ultraviolet light that is broadly tuneable and more than a million times more intense than the equivalent spontaneous undulator radiation. A strong feature of the scientific programme planned for 4GLS is dynamics experiments in a wide range of fields. Pump probe experiments will allow the study of chemical reactions and short-lived intermediates on the timescale of bond breaking and bond making, even for very dilute species. The high intensity of the FEL radiation will allow very high resolution in imaging applications. Funding for the first three years of the 4GLS project was announced by the UK Government in April 2003. This includes the research and development work necessary to produce a design study report, with the construction of an ERL-prototype. Additional funds have recently been awarded that will enable a study of the production of ultra-short pulsed X-rays from the ERL-prototype via Thomson scattering. It is anticipated that the full 4GLS facility will be available to users in 2011.
In a fixed-field alternating-gradient (FFAG) accelerator, eliminating pulsed magnet operation per... more In a fixed-field alternating-gradient (FFAG) accelerator, eliminating pulsed magnet operation permits rapid acceleration to synchrotron energies, but with a much higher beam-pulse repetition rate. Conceived in the 1950s, FFAGs are enjoying renewed interest, fuelled by the need to rapidly accelerate unstable muons for future high-energy physics colliders. Until now a ‘scaling’ principle has been applied to avoid beam blow-up and loss. Removing this restriction produces a new breed of FFAG, a non-scaling variant, allowing powerful advances in machine characteristics. We report on the first non-scaling FFAG, in which orbits are compacted to within 10 mm in radius over an electron momentum range of 12–18 MeV/c. In this strictly linear-gradient FFAG, unstable beam regions are crossed, but acceleration via a novel serpentine channel is so rapid that no significant beam disruption is observed. This result has significant implications for future particle accelerators, particularly muon and high-intensity proton accelerators.
The CERN PC-based ISOLDE control system has been installed at the SRS electron storage ring at Da... more The CERN PC-based ISOLDE control system has been installed at the SRS electron storage ring at Daresbury Laboratory. The use of Windows NT for the control consoles together with PC and VME front-end computers running under several operating systems has resulted in a flexible and reliable system for accelerator control. The implementation and philosophy of control application programs, based around a suite of Microsoft Visual Basic and Excel programs, is described. In particular, the use of Excel to provide adaptable programs online allows rapid generation of new control functions; orbit correction and servoing at the application level are described as examples of this
4GLS is a suite of accelerator-based light sources planned to provide state-of-the-art radiation ... more 4GLS is a suite of accelerator-based light sources planned to provide state-of-the-art radiation in the low energy photon regime. Superconducting energy recovery linac (ERL) technology will be utilised in combination with a variety of free electron lasers (IR to XUV), undulators and bending magnets. The 4GLS undulators will generate spontaneous high flux, high brightness radiation, of variable polarisation from 3 - 800 eV, optimised in the lower harmonics up to about 200 eV. Viable radiation at energies up to several keV may be provided from multipole wiggler magnet radiation. The ERL technology of 4GLS will allow shorter bunches and higher peak photon fluxes than possible from storage ring sources. It will also give users the added bonuses of pulse structure flexibility and effectively an infinite beam lifetime. VUV and XUV FELs will be used to generate short pulses (in the fs regime) of extreme ultraviolet light that is broadly tuneable and more than a million times more intense than the equivalent spontaneous undulator radiation. A strong feature of the scientific programme planned for 4GLS is dynamics experiments in a wide range of fields. Pump probe experiments will allow the study of chemical reactions and short-lived intermediates on the timescale of bond breaking and bond making, even for very dilute species. The high intensity of the FEL radiation will allow very high resolution in imaging applications. Funding for the first three years of the 4GLS project was announced by the UK Government in April 2003. This includes the research and development work necessary to produce a design study report, with the construction of an ERL-prototype. Additional funds have recently been awarded that will enable a study of the production of ultra-short pulsed X-rays from the ERL-prototype via Thomson scattering. It is anticipated that the full 4GLS facility will be available to users in 2011.
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