The magnetic toroidal sector as a broad-band electron–positron pair spectrometer I. lepton trajectories

Abstract

We report an analysis of electron-optical properties of a toroidal magnetic sector spectrometer and examine parameters for its implementation in a relativistic heavy-ion storage ring like HESR. For studies of free-free pair production in heavy-ion atom collisions this spectrometer exhibits very high efficiencies for coincident e + -epair spectroscopy over a wide range of momenta of emitted lepton pairs. The high coincidence efficiency of the spectrometer is the key for stringent tests of theoretical predictions for the coincident positron-and electron emission characteristics and for the phase space correlation of lepton vector momenta in free-free pair production.

Heavy-ion storage rings and their use in precision experiments with highly charged ions

“…This resulting challenge on coincidence efficiencies has so far inhibited any benchmark test of the predictions of theory. A new toroidal lepton spectrometer for simultaneous cover of the entire electron and positron phase space suitable for implementation into the future HESR storage ring has been recently proposed [351]. This should open a new window on stringent tests for the most advanced pair production theories.…”