Isobar Magnetic Field Calculation (2012 Mass Table)

Isobar Magnetic Field Calculation (2012 Mass Table)
Testing this at this time

Enter mass number (A) and atomic number (Z). Energy is assumed to be 39.585 keV and 198.185 keV as calculated from optics calculations fit to our usual 40 and 200 keV setpoint values.

A =
Z =



Comments about isobar separation at HRIBF:

  • Mass excess values are from the 2012 mass table of G. Audi, M. Wang, A. H. Wapstra, F. G. Kondev, M. MacCormick, X. Xu, and B. Pfeiffer, Chinese Physics C 36, 1287 (2012) and M. Wang, G. Audi, A. H. Wapstra, F. G. Kondev, M. MacCormick, X. Xu, and B. Pfeiffer, Chinese Physics C 36, 1603 (2012). This version of the Mass Table was taken from AMDC at IMP in China;
  • Isobaric mass differences are given as
    M/dM = A * 931.5 / (dM1 - dM2)
    where dM1 is the mass excess of the desired beam and dM2 is the mass excess of the neighboring isobars.
  • The isobar separator has a resolving power of M/dM~20,000; however, the isobaric separation actually achieved will depend not only on isobaric mass differences but also on the beam emittance, energy spread, and isobar intensity ratios.
  • The dispersion of the isobaric separator is given by:
    dx(mm) = 5163 * dM/M (or dE/E if energy spread dominates).
    This corresponds to 0.258 mm for M/dM = 20,000.
  • Partial isobaric separation will usually be possible for M/dM<10,000, but may result in reduced beam intensity.
  • Energy is determined by the anode voltage (+0.150 kV), ion source voltage (+/-40 kV), and platform voltage (+/-160 kV). Typical energy for injection into the tandem is 200.15 keV.

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