### 44.3 Atomic and Nuclear Physics

`GSL_CONST_MKSA_ELECTRON_CHARGE`

  The charge of the electron, e.

`GSL_CONST_MKSA_ELECTRON_VOLT`

  The energy of 1 electron volt, eV.

`GSL_CONST_MKSA_UNIFIED_ATOMIC_MASS`

  The unified atomic mass, amu.

`GSL_CONST_MKSA_MASS_ELECTRON`

  The mass of the electron, m_e.

`GSL_CONST_MKSA_MASS_MUON`

  The mass of the muon, m_\mu.

`GSL_CONST_MKSA_MASS_PROTON`

  The mass of the proton, m_p.

`GSL_CONST_MKSA_MASS_NEUTRON`

  The mass of the neutron, m_n.

`GSL_CONST_NUM_FINE_STRUCTURE`

  The electromagnetic fine structure constant \alpha.

`GSL_CONST_MKSA_RYDBERG`

  The Rydberg constant, Ry, in units of energy. This is related to the Rydberg inverse wavelength R_\infty by Ry = h c R_\infty.

`GSL_CONST_MKSA_BOHR_RADIUS`

  The Bohr radius, a_0.

`GSL_CONST_MKSA_ANGSTROM`

  The length of 1 angstrom.

`GSL_CONST_MKSA_BARN`

  The area of 1 barn.

`GSL_CONST_MKSA_BOHR_MAGNETON`

  The Bohr Magneton, \mu_B.

`GSL_CONST_MKSA_NUCLEAR_MAGNETON`

  The Nuclear Magneton, \mu_N.

`GSL_CONST_MKSA_ELECTRON_MAGNETIC_MOMENT`

  The absolute value of the magnetic moment of the electron, \mu_e. The physical magnetic moment of the electron is negative.

`GSL_CONST_MKSA_PROTON_MAGNETIC_MOMENT`

  The magnetic moment of the proton, \mu_p.

`GSL_CONST_MKSA_THOMSON_CROSS_SECTION`

  The Thomson cross section, \sigma_T.

`GSL_CONST_MKSA_DEBYE`

  The electric dipole moment of 1 Debye, D.