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[en] On 17 December, after having seen many other physics machines come and go during its 33-year career, CERN's 600 MeV SynchroCyclotron (SC) is being shut down. Judged simply by its length (to say nothing of its quality), the research career of this machine testifies to the wisdom and imagination of the CERN pioneers who proposed it in the early 1950s
[en] AGOR is a cyclotron of the KVI in Groningen, Netherlands, used for research on theoretical physics. Plans are in progress to use the AGOR cyclotron for research and development of radiotherapy by means of 200 MeV protons. In this article attention is paid to several techniques to safely apply proton radiation therapy. 5 figs., 4 refs
[en] A spectrometer is being installed in a high intensity antiproton beam (LESBII) at the AGS. The beam momentum entering the target will be known to approximately +- 1/2%. The target is surrounded by a stereoscopic cylindrical drift chamber and thus the total charge of the event will be measured. The vertex will be reconstructed with an acccuracy of approximately +- 2 mm, allowing studies of annihilations with high resolution down to approximately 150 MeV/c. On one side of the target a large aperture (2.3 x .62 m2) magnet, covered on both sides with drift chambers and triggering - TOF scintillation counters, will measure particle and γ-ray energies with high resolution, as well as identify particles. The primary objective is to look for peaks in the γ-spectra coming from annihilations at rest by converting them in a thin (.05 x0) radiator before the magnet. Narrow peaks (< 1 MeV) which are produced with frequencies of approximately 10-3 or better are expected to be seen as 5sigma effects. The principle and details of the spectrometer are presented
[en] Relativistic, magnetically-focused proton radiography was invented at Los Alamos National Laboratory using the 800 MeV LANSCE beam, and is inherently well-suited to imaging dense objects, at areal densities >20 g cm-2. However, if the unscattered portion of the transmitted beam is removed at the Fourier plane through inverse-collimation, this system becomes highly sensitive to very thin media, of areal densities <100 mg cm-2. Here, this inversecollimation scheme is described in detail and demonstrated by imaging Xe gas with a shockwave generated by an aluminum plate compressing the gas at Mach 8.8. With a 5-mrad inverse collimator, an areal density change of just 49 mg cm-2 across the shock front is discernible with a contrast-to-noise ratio of 3. Geant4 modeling of idealized and realistic proton transports can guide the design of inverse-collimators optimized for specific experimental conditions and show that this technique performs better for thin targets with reduced incident proton beam emittance. This work increases the range of areal densities to which the system is sensitive to span from ~25 mg cm-2 to 100 g cm-2, exceeding three orders of magnitude. This enables the simultaneous imaging of a dense system, as well as thin jets and ejecta material that are otherwise difficult to characterize with high-energy proton radiography.