def synchrotron_cooling_constant(B):
    """
    Compute the characteristic cooling constant for synchrotron cooling

    Define a factor that is dependent on the magnetic field B.
    The cooling time of an electron at energy gamma is
    DT = 6 * pi * me*c / (sigma_T B^2 gamma)
    DT = (1.29234E-9 B^2 gamma)^-1 seconds
    DT = (cool * gamma)^-1 seconds
    where B is in Gauss.

    """
    bulk_gamma = 300.0
    const_factor = 1.29234e-09
    C0 = const_factor * B ** 2
    return C0
