Measuring and matching transport optics at Jefferson Lab

Well-controlled optical transport over long range is important for many types of nuclear and high energy physics experiments. It is essential in achieving the desired beam parameters, minimizing optical sensitivity, and ensuring acceptable helicity correlated orbit differences for parity-type experiments. A precise and rigorous program for evaluating optical matching errors, and a deterministic algorithm for obtaining global matching solutions thus holds considerable promise for both accelerator design and operation, although the latter has defied attempts so far due to its almost intractable complexity. For the CEBAF accelerator at Jefferson Lab, this difficulty is further exacerbated by the extreme matching condition necessary for a 5 pass recirculating linac, elements that can introduce considerable optical error, and loss of longrange difference orbit orthogonality due to these effects, all of which impose a very tight demand on the accuracy of the measured transfer matrix as input to the matching algorithm. Research in methods for both measuring and matching optical transport has led to recent successful demonstration of deterministic matching of the optical transport of CEBAF. The global nature of the matching algorithm allows efficient exploration of solutions not easily accessible by traditional methods and serves to signal configuration flaws in the machine.