Polarized muon spins in pulsed magnetic fields: A new method to study delayed muonium formation

A transverse pulsed (less than or similar to 10 mT) magnetic field method i n mu SR is presented and studied in detail in view of applications to exper imental investigations of "delayed" muonium and muonium radical formation. The presence of longitudinal static fields for initial "spin-locking" purpo ses is analyzed and tested in the context of the adiabatic approximation. T he crossover between the sudden and adiabatic regimes is measured for both muonium and free muons. The method also makes mu SR experiments possible at frequencies above the natural bandwidth of pulsed beams.