Holder, D. J.

Paper	Title	Page
MOPC040	COBALD - an Inverse Compton Back-scattering Source at Daresbury	160
	D. J. Holder STFC/DL/ASTeC, Daresbury, Warrington, Cheshire D. Laundy STFC/DL, Daresbury, Warrington, Cheshire G. Priebe STFC/DL/SRD, Daresbury, Warrington, Cheshire
	An inverse Compton Back-scattering (CBS) ultra-short pulsed x-ray source driven by the multi-terawatt laser installed at Daresbury’s Energy Recovery Linac Prototype (ERLP) is being developed. Hard x-rays, ranging from 15 keV to 30 keV, depending on the backscattering geometry, will be generated through the interaction of the laser pulse and an electron bunch delivered by ERLP. The X-rays created contain 15 ·106 photons per pulse from head-on collisions, with a pulse duration comparable to that of the incoming electron bunch, and 5 ·106 photons per pulse from side-on collisions, where the laser pulse defines the pulse width. The peak spectral brightness of ≈1020 photons/s/mm2/mrad2/0.1% ΔE/E is close to that of 4th-generation synchrotron light sources. Called COBALD, it will initially be used as a short pulse diagnostic for the ERLP electron beam and will explore the extreme challenges of photon/electron beam synchronization, which is a fundamental requirement for all accelerator-based (whether FEL or spontaneous SR) dynamics programmes. Furthermore, a fast-melting experiment will be used as a diagnostic tool to provide further information on the stability of the source.
MOPC062	Results from ALICE (ERLP) DC Photoinjector Gun Commissioning	208
	Y. M. Saveliev, D. J. Holder, B. D. Muratori, S. L. Smith STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
	The Energy Recovery Linac Prototype (ERLP) DC photoinjector gun has been commissioned and the beam characteristics measured. The gun has demonstrated the nominal ERLP parameters of 350 keV electron energy, 80pC bunch charge and ~140 ps bunch length (at 10% level). The bunch parameters were measured at different bunch charges from 1 pC up to 80 pC. Special attention was given to measurements of the beam transverse emittance (using a movable slit), correlated and uncorrelated energy spread (using an energy spectrometer) and bunch length (using a transverse RF kicker) at each bunch charge. The effect of the 1.3 GHz RF buncher on the bunch length was also investigated. The experimental results are then compared with ASTRA simulations. Experimental results obtained from the investigation of several other issues including the beam characteristics in the presence of field emission from the cathode and in the presence of strong beam halo are also presented and discussed.
TUOAM02	The Status of the Daresbury Energy Recovery Linac Prototype	1001
	D. J. Holder, P. A. McIntosh, S. L. Smith STFC/DL/ASTeC, Daresbury, Warrington, Cheshire N. Bliss STFC/DL, Daresbury, Warrington, Cheshire A. R. Goulden STFC/DL/SRD, Daresbury, Warrington, Cheshire
	This paper provides an update on the progress with the building and commissioning of the Energy Recovery Linac Prototype (ERLP). The past year has seen a number of notable achievements as well as a number of obstacles to overcome. The detailed results from the gun commissioning work are described elsewhere at this conference. ERLP is a 35 MeV technology demonstrator being built as part of the UK's R&D programme to develop its next-generation light source (NLS). It is based on a combination of a DC photocathode electron gun, a superconducting injector linac and a main linac operating in energy recovery mode. These drive an IR-FEL, an inverse Compton Back-Scattering (CBS) x-ray source and a terahertz beamline. The priorities for ERLP are to gain experience of operating a photoinjector gun and superconducting linacs; to produce and maintain high-brightness electron beams; to achieve energy recovery from an FEL-disrupted beam; the development of an electro-optic longitudinal profile monitor and to study challenging synchronisation issues. ERLP will also act as an injector for what will be the world's first non-scaling, Fixed-Field Alternating Gradient (FFAG) accelerator called EMMA.
	Slides
TUPC002	Design of a Tomography Module for the PITZ Facility	1038
	G. Asova, K. Floettmann DESY, Hamburg D. J. Holder, B. D. Muratori STFC/DL/ASTeC, Daresbury, Warrington, Cheshire S. Khodyachykh, S. A. Korepanov, M. Krasilnikov, S. Rimjaem, F. Stephan DESY Zeuthen, Zeuthen
	The goal of the Photo Injector Test Facility at DESY in Zeuthen (PITZ) is to develop sources of high phase-space density electron beams that are required for the successful operation of SASE FELs. This requires detailed characterization of the sources and therefore the development of suitable advanced diagnostics. As part of the ongoing upgrade towards higher beam energies, new diagnostics components are being installed. An example is a tomography module for transverse phase space reconstruction which is designed to operate in the energy range between 15 and 40 MeV. The module consists of four observation screens with three FODO cells between them. A number of upstream quadrupoles are used to match the beam envelope parameters to the optics of the FODO lattice. This contribution presents the final design of the tomography module. Data from numerical simulations are used to illustrate the expected performance and to compare it to a simplified setup of two quadrupoles. The quality of the reconstruction is revised with the help of different algorithms.
WEPC062	The SRS at Daresbury Laboratory: a Eulogy to the World's First Dedicated High-energy Synchrotron Radiation Source	2133
	D. J. Holder, N. G. Wyles STFC/DL/ASTeC, Daresbury, Warrington, Cheshire P. D. Quinn STFC/DL/SRD, Daresbury, Warrington, Cheshire
	2008 marks the last year of operation of the Synchrotron Radiation Source (SRS) at Daresbury Laboratory, which circulated its first 2 GeV beam in 1981. This paper provides a look back at the significant milestones passed on the way and records the achievements of many of those involved in its thirty-year programme. Many of the technologies and techniques developed at the SRS at Daresbury are now standard practice at synchrotron light sources around the world; and there are few light source laboratories that do not benefit from the skills of someone who spent their formative years working on the SRS. The provision of synchrotron light for the UK is now being met by DIAMOND, whose success is a testament to the skills of its designers, honed as they were on the SRS at Daresbury. These skills are now being used to design the UK’s next-generation light source, to provide the pulsed and longer-wavelength light that DIAMOND cannot.
WEPC085	Matching with Space Charge	2192
	B. D. Muratori, D. J. Holder STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
	This paper explores the possibility of performing matching in the presence of space charge to an acceptable and useful level. Space charge gives rise to a mismatch for beams at low energies. This mismatch can be very harmful for certain applications, for example the tomography diagnostic of the PITZ2 test line. In this case, the Twiss parameters at the start of the tomography section have to be as close as possible to the design ones. As can be shown by a thin lens approximation, all the Twiss parameters at the start of the tomography section are fully determined, as is the quadrupole strength, once the length of the FODO cells is chosen. With the presence of space charge it is necessary to introduce a modification to the original matching, itself performed with a standard optimizing routine. The idea is that this modification can only compensate for the linear part of space charge and it does so by changing the quadrupole strengths. The theory is verified by using an very simple test line consisting of just two quadrupoles and modeling it using GPT (General Particle Tracer). This results in modified values for the quadrupole strengths to accommodate the effect of space charge.