I AN ASSESS~MENT OF THE EFFECTS OF RADIATION ON PERMANENT-MAGNET MATERIAL IN THE ALS INSERTION DEVICES *

Electrons that are IOSI from the beam during nom-A operation of a synchrotron radiation source and during a beam dump at the end of 1 mn produce both ionizing radiation and neutrons. This radiation has the potentirl oi damaging sensitive maxials. in particular those that ne:rd to be very close to the beam. In the ~1,‘ooiers and undulators for the.Wxnced Light Source (ALS) 31 LBL. magnetic materials such 3s the veq-high-performance neodymium-iron-boron uill be 3s close 3s I cm 3wny from the electron beam during operation. TINS mxctial. which is preferred because of its high rcmsnsnce. is known ‘o be more sensitive IO radiation than some other magnetic m;ltcrisls. Simple energy loss estimates and the EGSJ code were used to estimztr the radiation levels in the ALS insertion devices in the regions of the magnetic mzmxi~ls. The radiation levels were estimated for both aluminum and stanless steel vacuum chambers to determine if one would provide significantly better shis!ding. \Vs conclude that SVd-Fe-B can be used in the ALS insertion devices and that there is little difference in the radiation levels for aluminum 2nd stainless steel vacuum vessels. 1. lnncduction The issue of radiation damage in permanent-magnet material \vas raised when initial work on the concept of! _ a generic insertion device structure for the.L\LS began in the fall of 1989. Two important questions had IO be addressed before proceeding with the detailed design