A Bragg Detector For AMS Measurement

AMS is the most sensitive mass spectrometer for determination of ratio of isotopes. The limitation of detection of AMS can reach 104 atoms, or isotopic ratio of 10-15. The most difficulty in AMS measurements comes from the interference of isobars, for example, the interference of 26Mg in 26A1 measurement. Detector is one of the important parts of AMS instrument. The kind of detector for AMS should be chosen according to the ions to be measured. In order to measure heavy ions with better discriminating isobars, A Bragg detector has been set up for AMS in our lab.The Bragg detector is mainly made up of gas filled ionization chamber that absorbs all projects while working, including three main parts: anode, cathode and grid. Circles were set between the cathode and grid in order to attain a parallel electric field. Bragg curve achieved at the projectile direction can provide the information of total energy and Bragg peak. Then the ions can be identified through Z-E matrix.Characterization of the detector was initially tested with alpha particles of 241Am. Good results for energy and charge resolution wereobtained in the condition of 0.2V/cm.T