Preliminary design of a synchrotron radiation exit port crotch for Cornell B-factory

The proposed Cornell B-factory offers great possibilities for the next generation of synchrotron sources and at the same time presents many challenges to today's high heat-load cooling technology. One of the challenges, the exit port crotch, is discussed in this article. Its preliminary design consists of a beryllium thin tube with water cooling. Finite elements analysis shows that such a design should be able to tolerate a normal incident power density of 4.7 kW/mm2 at 2 meters from bending magnet radiation with a 55 meter radius at 8 GeV and 1 ampere of positron current. Our design consists of a tube that is almost parallel to the synchrotron beam with an incident angle of 2 degree(s). This dilutes the power density by a factor of approximately 30 reducing the heat load to a more manageable level. The tilt angle can be 15 degree(s) if the crotch is located 4 meters instead of 2 meters from the source.