The Mainz energy recovering Superconducting accelerator (MESA) - a versatile experimental arrangement based on a compact accelerator
Dr. Kurt Aulenbacher (Institut für Kernphysik)

Many breakthroughs in particle physics have been achieved by creating an innovative, accelerator-based experimental regime. The purpose of MESA is to explore such an opportunity by using the recently established Energy-Recovery-LINAC (ERL-) technology which allows for high luminosities (L ~ 1035 cm-2 s-1 ) on internal targets at /low/ electron beam energies of ~100 MeV. The ‘*M*ainz *E*nergy recovering *S*uperconducting *A*ccelerator’ (*MESA*) will provide a 100MeV c.w.-beam, a beam current of 10mA and a geometrical beam emittance of <50nm, the latter allowing for virtually lossless focussing through a windowless gas-target.
Due to energy recovery, the installed r.f-power can be reduced by a factor ~20 if compared to a conventional accelerator. * *MESA will also provide a high intensity, spin polarized external beam at 200 MeV. MESA will be used for at least two different particle physics experiments. First, ERL-operation will be exploited for “dark photon” (g’-) search in a region of the parameter space which adjoins the exclusion area covered by (g-2)m - one of the most prospective hunting grounds for explorative experiments. Second, considering a precision measurement of the Weinberg angle, the low energy, spin-polarized external beam of MESA creates significant advantages if compared to far bigger facilities.