Development of a μLCR facility at LAMPF

Abstract

It has long been recognized thatμLCR could profitably be done with the high intensity surface beam at LAMPF [1]. A spectrometer has been built that is matched to the LAMPF beam characteristics. The polarization information is obtained from a downstream array of counters while side counters, containing no polarization signal, monitor theμ ⁺ beam. Degraders select higher energy e⁺, thereby reducing rates and required counter segmentation while maintaining information content. We apply a ramped longitudinal field in addition to the static one to average over instabilities in theμ ⁺ beam. This field scan allows direct interpretation of data and does not require a prior estimate of the resonance structure of a sample. Flux coils monitor the applied ramp field and eddy-current induced fields. High average rate (2×10⁷ μ ⁺/s). good stability, and the versatile field scan permitted useful data to be collected from Cu, Al(Cu), Al, Si(Al), and polycrystalline Si targets.