## Atomic and Nuclear Physics

`GSL_CONST_MKS_ELECTRON_CHARGE`
  The charge of the electron, e.
`GSL_CONST_MKS_ELECTRON_VOLT`
  The energy of 1 electron volt, eV.
`GSL_CONST_MKS_UNIFIED_ATOMIC_MASS`
  The unified atomic mass, amu.
`GSL_CONST_MKS_MASS_ELECTRON`
  The mass of the electron, m_e.
`GSL_CONST_MKS_MASS_MUON`
  The mass of the muon, m_\mu.
`GSL_CONST_MKS_MASS_PROTON`
  The mass of the proton, m_p.
`GSL_CONST_MKS_MASS_NEUTRON`
  The mass of the neutron, m_n.
`GSL_CONST_NUM_FINE_STRUCTURE`
  The electromagnetic fine structure constant \alpha.
`GSL_CONST_MKS_RYDBERG`
  The Rydberg constant, Ry, in units of energy. This is related to the Rydberg inverse wavelength R by Ry = h c R.
`GSL_CONST_MKS_BOHR_RADIUS`
  The Bohr radius, a_0.
`GSL_CONST_MKS_ANGSTROM`
  The length of 1 angstrom.
`GSL_CONST_MKS_BARN`
  The area of 1 barn.
`GSL_CONST_MKS_BOHR_MAGNETON`
  The Bohr Magneton, \mu_B.
`GSL_CONST_MKS_NUCLEAR_MAGNETON`
  The Nuclear Magneton, \mu_N.
`GSL_CONST_MKS_ELECTRON_MAGNETIC_MOMENT`
  The absolute value of the magnetic moment of the electron, \mu_e. The physical magnetic moment of the election is negative.
`GSL_CONST_MKS_PROTON_MAGNETIC_MOMENT`
  The magnetic moment of the proton, \mu_p.