Abstract
Errors in delivering a uniformly distributed radiation dose to biological and material samples exposed to charged particle beams are a significant problem for experimenters. In this paper, we discuss data collected on the uniform beam distributions produced for NASA's Space Radiation Laboratory (NSRL) at Brookhaven National Laboratory (BNL), using a method that was conceived theoretically and tested experimentally at BNL. This method [N. Tsoupas et al., Nucl. Sci. Eng. 126, 71 (1997)] of generating uniform beam distributions on a plane normal to the beam's direction relies only on magnetically focusing the transported beam; no collimation of the beam is required or any other type of interaction of the beam with materials other than the target material. The method compares favorably with alternative methods of producing such distributions, and it can be applied to the entire energy spectrum of charged particle beams that are delivered to the NSRL's experiments by the Booster for the Alternating Gradient Synchrotron at BNL.
Highlights
Researchers frequently require uniform irradiation of materials or biological samples by ion beams
The facility has provided uniformly distributed beams of various ions including protons, 12C, 16O, 28Si, 39Cl, 56Fe, and 48Ti, at the target. These ion beams are first accelerated by the Booster of the Alternating Gradient Synchrotron (AGS) to various energies from 50 to 3000 MeV=n, slowly extracted and transported via the NASA Space Radiation Laboratory (NSRL)’s beamtransport line to the sample’s location which is 100 m downstream from the beginning of this line
The construction of the NSRL facility at Brookhaven National Laboratory (BNL) was completed in March 2003, and the beam-transport line commissioned in June 2003 for use by NASA and other scientific organizations for experiments involving the irradiation of materials and biological samples [3,4]; part of NASA’s research effort is to expose biological samples to a variety of ions similar to those that will be encountered on a spacecraft traveling to Mars
Summary
Researchers frequently require uniform irradiation of materials or biological samples by ion beams. At the NASA Space Radiation Laboratory (NSRL) at Brookhaven National Laboratory (BNL), we employ a unique method of generating uniformly irradiated areas ranging from 10 10 cm to 20 20 cm2 [1,2] This facility, which started operations in 2003 [3], is used by NASA to uniformly irradiate various materials and biological samples with ion beams. The present method of producing uniformly distributed beams over a rectangular area normal to the beam’s direction is based on third-order magnetic optics; it employs octupole magnetic elements located along the beam line. These elements transform the otherwise normally distributed beam at the target into a uniformly distributed one. The projection of the ‘‘beam’s distribution’’ along the horizontal or vertical direction will be referred to, respectively, as the horizontal- or verticalbeam profile
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