Four-dimensional emittance measurement at the Spallation Neutron Source

A coasting hadron beam with an elliptical transverse profile, uniform charge density, and small four-dimensional (4D) emittance could improve accelerator performance in several contexts. phase space painting method to generate such a distribution is being tested the Spallation Neutron Source (SNS) accumulator ring. critical component of these efforts measure 4D during accumulation. The can be reconstructed from measured profiles two ways: multi-optics method, optics between reconstruction measurement location are varied; fixed-optics multiple locations used without modifying optics. faster but lead large uncertainty emittance. In this paper, we implement variant using four available wire-scanners near SNS target. We also modify wire-scanner region reduce method. then demonstrate usefulness by reconstructing evolution accumulation