AMS AT THE MUNICH GAS-FILLED ANALYZING MAGNET SYSTEM GAMS

A dedicated gas-fined magnet with a deflection angle of 135 degrees ha s been installed for isobaric suppression in AMS. The optimum bending angle of 135 degrees has been calculated with a Monte Carlo code. Amon g different gases studied, nitrogen showed the best compromise between multiple scattering and charge changing cross sections for superior r esolution of isobars. Other components of this system are a time-of-fl ight measurement with a 250 ps resolution and an ionization chamber wi th five Delta E measurements, position and angle sensitivity in the ho rizontal plane and angle sensitivity in the vertical. Test measurement s have been performed for Cl-36, Mn-53, Ni-59 and Fe-60. The excellent resolution achieved allows for the first time sensitive AMS measureme nts of Mn-53. The measurement of the Fe-60 concentration in the meteor ite Tlacotepec registered no events at a sensitivity level of 1.5 x 10 (-14).