COLLECTION OPTICS WITH THE HORN TYPE FOCUCING ELMENT MADE WITH SEPARATE CONDUCTORS
We describe the device for focusing of charged particles by the system of separated conductors which follow the parabolic profile. Basically this is a horn-type focuser, but with the individual conductors instead of continuous surface. This device allows substantial reduction of fabrication cost with the same focusing properties as the continuous parabolic surface. We recommend this “bird-cage” type system for focusing pions/muons in the projects under discussion in many Laboratories around the World. OVERVIEW Necessity for good quality secondary beams is well argumented topic for the high energy physics [1]-[3]. The horn-like focusing elements (lenses) are broadly in use in many laboratories for collection of secondary particles in the proton lines. One example of usage of miniature copy of such lens for collection of positrons is known from Budker INP [4]. For collection of pions the horns reach sized of ~0.5 m in diameter and ~2 m long [5]. Fabrication of thin wall parabolic surface of this scale represents substantional technological difficulties. Typically it is fabricated from solid billets of 40-6061-T6 Aluminum with typical lengths of 40 cm [5]. Three segments are electron beam welded together. Typical thickness of the parabolic wall is around 2mm. In all horn-like focusing devises the secondary beams running through material of paraboloid. In this publication we made a proposition to approximate continuous surface of paraboloid with limited number of separate conductors. This approach delivers significant simplifications in technology of fabrication. The payoff for this-a distortions of trajectories can be made acceptable as the angular spread of secondary beams is significant. Any way it is comparable with divergences obtained as a result of multiple scattering in material of paraboloid.
Fermilab Neutrino - Horn Focussing System
The study of neutrino physics at Fermilab in the 15-foot bubble chamber and in electronic counter detectors is being actively and agressively pursued. To increase the flux of neutrinos through the detectors over the entire neutrino energy spectrum, a high efficiency horn-focussed beam was developed. The horn system is well known for its high acceptance and hi hly achromatic focussing of charged particles 4 produced at the production target into a low divergence beam. This meson beam is allowed to decay in a 400 m long vacuum region producing neutrinos and muons. The muons are absorbed from the beam by using 1 Km of earth allowing the filtered neutrino beam to pass through the experimental detectors. This report covers the equipment and results of the focussing region.
PULSE: a high-repetition-rate linac driver for x-ray FELs
We describe a staged concept for a linac-based freeelectron laser providing coherent tuneable VUV and soft X-ray output with pulse lengths down to 10 fs or less. Use of 1.3 GHz cryomodules operated with CW RF will allow flexible pulse patterns at potentially very high repetition rates up to 1 MHz. We consider the options for FELs that may be included in a facility of this type.