EMuS at CSNS-II

Abstract

Experimental muon source (EMuS) at China’s spallation neutron source (CSNS) is a multidisciplinary project intended mainly for μSR, muon induced x-ray emission and imaging applications, and is envisaged for muonium to antimuonium conversion physics or neutrino cross sections measurements. These goals are achieved by intense beams of surface and decay muons produced by pions decaying at rest or in flight respectively, and neutrinos. At EMuS, pions are produced when a target of graphite is interacting with a 25 kW primary proton beam provided from the rapid cycling synchrotron (RCS) of CSNS at phase-II. Two schemes of EMuS are being studied. The main scheme is called baseline and is operating in surface or decay muons modes and secondary for neutrinos. It is employing a target station with a superconducting capture solenoid and a conical target of graphite for the capture and collection of surface muons or charged pions, a long superconducting line for the transport of surface muons or the decay of charged pions, and shorter beamlines with which extracted surface or decay muons are led to μSR, muon induced x-ray emission and imaging experiments. In addition, upstream from the superconducting target station, a vertical μSR beamline of quadrupoles is foreseen to run in parallel, employing a thin slab of graphite for the production of surface muons with high polarization. The secondary scheme is called simplified and operating for surface muons and possibly for muon induced x-ray emission experiments. It is employing a conventional rotated thick slab of graphite located sideways from a quadrupole triplet collector, a dipole and a beamline of quadrupoles for the selection and transport of surface muons respectively to μSR experiments. In this proceedings, the different layouts of target stations and beamlines are discussed.