| # Gaudi Framework, version v20r2
Generated: 18 Jul 2008

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# PhysicalConstants.h File Reference

`#include "GaudiKernel/SystemOfUnits.h"`

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## Namespaces
namespace | Gaudi
namespace | Gaudi::Units
## Variables
static const double | Gaudi::Units::pi = 3.14159265358979323846
static const double | Gaudi::Units::twopi = 2*pi
static const double | Gaudi::Units::halfpi = pi/2
static const double | Gaudi::Units::pi2 = pi*pi
static const double | Gaudi::Units::Avogadro = 6.0221367e+23/mole
static const double | Gaudi::Units::c_light = 2.99792458e+8 * m/s
static const double | Gaudi::Units::c_squared = c_light * c_light
static const double | Gaudi::Units::h_Planck = 6.6260755e-34 * joule*s
static const double | Gaudi::Units::hbar_Planck = h_Planck/twopi
static const double | Gaudi::Units::hbarc = hbar_Planck * c_light
static const double | Gaudi::Units::hbarc_squared = hbarc * hbarc
static const double | Gaudi::Units::electron_charge = - eplus
static const double | Gaudi::Units::e_squared = eplus * eplus
static const double | Gaudi::Units::electron_mass_c2 = 0.51099906 * MeV
static const double | Gaudi::Units::proton_mass_c2 = 938.27231 * MeV
static const double | Gaudi::Units::neutron_mass_c2 = 939.56563 * MeV
static const double | Gaudi::Units::amu_c2 = 931.49432 * MeV
static const double | Gaudi::Units::amu = amu_c2/c_squared
static const double | Gaudi::Units::mu0 = 4*pi*1.e-7 * henry/m
static const double | Gaudi::Units::epsilon0 = 1./(c_squared*mu0)
static const double | Gaudi::Units::elm_coupling = e_squared/(4*pi*epsilon0)
static const double | Gaudi::Units::fine_structure_const = elm_coupling/hbarc
static const double | Gaudi::Units::classic_electr_radius = elm_coupling/electron_mass_c2
static const double | Gaudi::Units::electron_Compton_length = hbarc/electron_mass_c2
static const double | Gaudi::Units::Bohr_radius = electron_Compton_length/fine_structure_const
static const double | Gaudi::Units::alpha_rcl2
static const double | Gaudi::Units::twopi_mc2_rcl2
static const double | Gaudi::Units::k_Boltzmann = 8.617385e-11 * MeV/kelvin
static const double | Gaudi::Units::STP_Temperature = 273.15*kelvin
static const double | Gaudi::Units::STP_Pressure = 1.*atmosphere
static const double | Gaudi::Units::kGasThreshold = 10.*mg/cm3
static const double | Gaudi::Units::universe_mean_density = 1.e-25*g/cm3