Index of content:
Volume 80, Issue 3, March 2009
- PARTICLE SOURCES, OPTICS AND ACCELERATION; PARTICLE DETECTORS
80(2009); http://dx.doi.org/10.1063/1.3086424View Description Hide Description
This article reports on an experimental method to fully reconstruct laser-accelerated proton beam parameters called radiochromic filmimaging spectroscopy (RIS). RIS allows for the characterization of proton beams concerning real and virtual source size, envelope- and microdivergence, normalized transverse emittance, phase space, and proton spectrum. This technique requires particular targets and a high resolution protondetector. Therefore thin gold foils with a microgrooved rear side were manufactured and characterized. Calibrated GafChromic radiochromic film (RCF) types MD-55, HS, and HD-810 in stack configuration were used as spatial and energy resolved filmdetectors. The principle of the RCF imaging spectroscopy was demonstrated at four different laser systems. This can be a method to characterize a laser system with respect to its proton-acceleration capability. In addition, an algorithm to calculate the spatial and energy resolved proton distribution has been developed and tested to get a better idea of laser-accelerated proton beams and their energy deposition with respect to further applications.
80(2009); http://dx.doi.org/10.1063/1.3093810View Description Hide Description
Single-turn extraction from the Japan Atomic Energy Agency AVF cyclotron with a number of 110 using a flat-top (FT) acceleration system has been achieved to reduce the energy spread of an ion beam for microbeam formation with energy up to hundreds of MeV and to increase extraction efficiency from the cyclotron. In order to generate a FT waveform voltage using the fifth-harmonic frequency on a dee electrode, a FT resonator was designed using MAFIA code to achieve downsizing and low power consumption. The FT resonator, coupled to the main resonator through a coupling capacitor, covered the full range of the fifth harmonic frequency from 55 to 110 MHz. Various ion beams, accelerated using different acceleration harmonic modes of and 2, such as 220 MeV , 260 MeV , and 45 MeV , were developed by FT acceleration. A clear turn separation of the beam bunches was successfully observed at the extraction region of the large-scale AVF cyclotron with number of revolutions greater than 200. As a result, high extraction efficiency (over 95%) from the cyclotron was achieved. Single-turn extraction was confirmed by counting the number of beam bunches out of the cyclotron for an injected beam pulsed by a beam chopping system in the injection line. The energy spread of the 260 MeV beam was measured using an analyzing magnet, and we verified a reduction in the energy spread from to 0.05% by single-turn extraction after FT acceleration.