TRIUMF extraction and 500 MeV beamline optics

Abstract

The 2A beamline, one of the TRIUMF cyclotron primary extraction beamlines, is 60 m in length. It is now routinely operating up to 70 uA (proton beam) at 500 MeV for ISAC. ISAC requires a diffuse spot of specific size on the radioactive beam production target at the end of 2A. To help achieve this, we developed a program aimed at obtaining a better understanding and more accurate description of 2A optics and the extracted beam from the cyclotron. The beam sizes along 2A were measured with profile monitors and compared with theoretical predictions. During the course of this work, we discovered that the transfer matrix, involved in the optics calculations, between the stripping foil and the beamline entrance was incorrect. After correcting this error, we obtained good agreement between the measured and calculated envelopes. We report on the details of this work as well as on a measurement of the beam characteristics as a function of stripper foil thickness.