Design and test of a beam profile monitoring device for low intensity radioactive beams

Development efforts have gone into the construction and performance testing of a device that can be used to provide snap shot images of the beam profile. It is intended to function even at very low ion intensities, such as those expected from a rare-isotope accelerator. Intensity profiles and emittance analysis are among the most critical tools used for optimizing beam transport through accelerators. This article describes the design and performance of a beam image monitor. The device is sensitive at a wide dynamic range which spans from ;10 to ;10 pps. With the advent of double-plane slits or a pepper pot plate, this system can be used to scan transverse emittance profiles in both the x – x8 and y – y8 phase space planes, simultaneously. Conventional diagnostic devices used for heavy ion accelerators generally require at least 10 pps intensity to carry out similar diagnostics, which is not practical when considering beams with very low intensities, such as rare isotope beams. Furthermore, the detection system used here can be used for a wide range of incident ion velocities. Compared with solid-state detectors and scintillators that are inserted directly into the beam, this type of detection system is less susceptible to beam induced damage resulting in longer lifetimes and less maintenance. The test was done using single charge state Kr beams at energies ranging from 3.6 to 18 keV/u. The device’s sensitivity was monitored for intensities below 10 pps and an emittance scan was recorded and analyzed. The spatial resolution was characterized by comparing the emittance profile with that obtained by a wire scanning device which had better resolution but was sensitive only to intensities above 10 pps. Recently, the device has been used to aid in the transport of ;6 MeV/u radioactive beams, such as F, produced by pickup reactions with a gas cell target at the ATLAS accelerator facility. © 2002 American Institute of Physics. @DOI: 10.1063/1.1419227#