An advanced laboratory in nuclear-isotope mass spectroscopy

We describe an experiment in nuclear-isotope mass spectroscopy, suitable fo r an advanced physics laboratory, which,utilizes a relatively inexpensive c ommercial 60 degrees-dipole residual gas analyzer. Students measure the ter restrial abundance of the isotope Ne-22 relative to Ne-20 and compare this with recent measurements of this ratio in meteorites. These ratios provide clues to the astrophysical sites, astrophysical processes, and nuclear reac tions which formed these isotopes. The mass spectrometer is also used as a residual gas analyzer to examine the gas composition (O-2, N-2, H2O,...) at various pressures in a typical vacuum system. This gives students insight into the design of vacuum apparatus including the optimal selection of comp onents such as vacuum pumps for particular applications. (C) 1998 American Association of Physics Teachers.