SEARCH Articles Figures Tables Double focusing Double mass spectrometer Double-focusing mass Double-focusing sector Double-focusing sector field Double-focusing sector field mass Double-focusing sector field mass spectrometer Double-focusing sector mass Double-focusing sector mass spectrometer Double-focusing spectrometer Focusing geometry Johnson Mass spectrometer Nier-Johnson Mass spectrometer sector field Nier mass spectrometer Nier-Johnson double-focusing Nier-Johnson geometry Sector Sector field Sector mass spectrometers Sectorization