[en] The ion yields and energy distributions of C^- and C₂^- ions sputtered from a graphite target by a 20 keV Cs⁺ beam, have been measured in the temperature range 80-880K. Assuming a velocity-dependent ionisation probability, the measured changes in the position of the peak of the energy distribution have been used to calculate the changes in the work-function of the emitting surface. It is concluded that the work-function reaches a broad minimum at approximately 500 K increasing thereafter by about 1.3 eV at the maximum achievable temperature in the experiment; this increase is accompanied by a corresponding decrease in the negative ion current by about a factor of 6. (author)

[en] Daresbury Laboratory houses a 20 MV tandem which has been in operation for over 4 years. Various proposals have been made to upgrade the facility by the addition of a post accelerator. One of these involved the addition of a large superconducting heavy ion linac capable of accelerating all masses up to the Coulomb barrier (1). Because of financial restrictions it was not possible to proceed with this scheme, so that when the resonators and cryostats which were to have been installed on the Oxford University folded tandem became available it was decided to install these as a post accelerator on the Daresbury machine. These modules will add about 5 MeV/charge to the ion energy and this will extend the range of nuclear physics experiments possible by a useful factor. The addition of further linac modules is an obvious possibility and this has been kept in mind in the design and specification of the layout and the helium refrigeration system. 3 references, 2 figures

No abstract available

[en] Energy distribution measurements on 20 keV beams of ¹²C^-, ³²S^-, ¹²⁷I^-, H^- and ¹⁶O^- have shown no obvious differences between H^- and ¹⁶O^- on the one hand, which are believed to be produced in an adsorbed layer on the target, and ¹²C^-, ³²S^-, and ¹²⁷I^- on the other which are part of the target material. All spectra have a single peak and a FWHM of the order of 10-12 eV. The significance of the energy distribution in the calculation of beam brightness is also discussed

[en] The Oxford Van de Graaff accelerator has been converted from a heavy ion machine into a single-ended accelerator for electrons. The purpose of the conversion was to provide a relatively intense (∝200 mA) pulsed beam of electrons, in the energy range of 3-4 MeV, for an experiment on the Smith-Purcell radiation. This paper describes the main problems of such a conversion (beam injection and transport through inclined field accelerating tubes, beam stability and electron gun reliability) in a situation where the emphasis was on low cost, short time delay and use of existing components, as far as possible. (orig.)

No abstract available

[en] An automated system was developed for measuring the emittance of beams from negative ion sources. The data are stored as two-dimensional spectra in a kicksorter and subsequently analyzed with a PDP-10 computer. The system was first used to measure the properties of, and assess the value of design changes to, a Middleton sputter source. Subsequently, the emittance of several different types of negative ion source were compared. A retarding field energy analyzer of high resolution was used to measure the beam energy spreads from the Middleton sputter source and from other negative ion sources, including a direct extraction duoplasmatron and a sputter Penning source. Typical spectra have a width of a few eV, with a small group of higher energy ions

No abstract available

[en] The radiation emitted by the interaction of an ultra-relativistic particle with a metallic grating (Smith-Purcell radiation) could be used as a very sensitive position sensor for a future Linear Collider or X-ray Free Electron Laser, with position resolution of 1 μm, or better. This article analyzes the physical principles underlying the operation of such a device and concludes with some of the practical issues in its implementation

[en] Recent measurements at Frascati of the Smith-Purcell radiation emitted from the interaction of a 2.3 MeV (total) electron beam with a 2.5 mm grating show clear evidence of coherent enhancement of the radiation, with power levels exceeding 100 mW at emission angles around 90 deg. relative to the beam direction. The experimental results are in reasonable agreement with theoretical predictions and suggest that Smith-Purcell radiation may offer a simple way of determining the shape and duration of short (picosecond) electron bunches