CLHEP 2.0.4.7 Reference Documentation
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00001 // -*- C++ -*- 00002 // $Id: PhysicalConstants.h,v 1.3.4.1.2.1 2008/11/04 17:24:39 garren Exp $ 00003 // ---------------------------------------------------------------------- 00004 // HEP coherent Physical Constants 00005 // 00006 // This file has been provided by Geant4 (simulation toolkit for HEP). 00007 // 00008 // The basic units are : 00009 // millimeter 00010 // nanosecond 00011 // Mega electron Volt 00012 // positon charge 00013 // degree Kelvin 00014 // amount of substance (mole) 00015 // luminous intensity (candela) 00016 // radian 00017 // steradian 00018 // 00019 // Below is a non exhaustive list of Physical CONSTANTS, 00020 // computed in the Internal HEP System Of Units. 00021 // 00022 // Most of them are extracted from the Particle Data Book : 00023 // Phys. Rev. D volume 50 3-1 (1994) page 1233 00024 // 00025 // ...with a meaningful (?) name ... 00026 // 00027 // You can add your own constants. 00028 // 00029 // Author: M.Maire 00030 // 00031 // History: 00032 // 00033 // 23.02.96 Created 00034 // 26.03.96 Added constants for standard conditions of temperature 00035 // and pressure; also added Gas threshold. 00036 // 29.04.08 use PDG 2006 values 00037 // 03.11.08 use PDG 2008 values 00038 00039 #ifndef HEP_PHYSICAL_CONSTANTS_H 00040 #define HEP_PHYSICAL_CONSTANTS_H 00041 00042 #include "CLHEP/Units/defs.h" 00043 #include "CLHEP/Units/SystemOfUnits.h" 00044 00045 namespace CLHEP { 00046 00047 // 00048 // 00049 // 00050 static const double pi = 3.14159265358979323846; 00051 static const double twopi = 2*pi; 00052 static const double halfpi = pi/2; 00053 static const double pi2 = pi*pi; 00054 00055 // 00056 // 00057 // 00058 static const double Avogadro = 6.02214179e+23/mole; 00059 00060 // 00061 // c = 299.792458 mm/ns 00062 // c^2 = 898.7404 (mm/ns)^2 00063 // 00064 static const double c_light = 2.99792458e+8 * m/s; 00065 static const double c_squared = c_light * c_light; 00066 00067 // 00068 // h = 4.13566e-12 MeV*ns 00069 // hbar = 6.58212e-13 MeV*ns 00070 // hbarc = 197.32705e-12 MeV*mm 00071 // 00072 static const double h_Planck = 6.62606896e-34 * joule*s; 00073 static const double hbar_Planck = h_Planck/twopi; 00074 static const double hbarc = hbar_Planck * c_light; 00075 static const double hbarc_squared = hbarc * hbarc; 00076 00077 // 00078 // 00079 // 00080 static const double electron_charge = - eplus; // see SystemOfUnits.h 00081 static const double e_squared = eplus * eplus; 00082 00083 // 00084 // amu_c2 - atomic equivalent mass unit 00085 // - AKA, unified atomic mass unit (u) 00086 // amu - atomic mass unit 00087 // 00088 static const double electron_mass_c2 = 0.510998910 * MeV; 00089 static const double proton_mass_c2 = 938.272013 * MeV; 00090 static const double neutron_mass_c2 = 939.56536 * MeV; 00091 static const double amu_c2 = 931.494028 * MeV; 00092 static const double amu = amu_c2/c_squared; 00093 00094 // 00095 // permeability of free space mu0 = 2.01334e-16 Mev*(ns*eplus)^2/mm 00096 // permittivity of free space epsil0 = 5.52636e+10 eplus^2/(MeV*mm) 00097 // 00098 static const double mu0 = 4*pi*1.e-7 * henry/m; 00099 static const double epsilon0 = 1./(c_squared*mu0); 00100 00101 // 00102 // electromagnetic coupling = 1.43996e-12 MeV*mm/(eplus^2) 00103 // 00104 static const double elm_coupling = e_squared/(4*pi*epsilon0); 00105 static const double fine_structure_const = elm_coupling/hbarc; 00106 static const double classic_electr_radius = elm_coupling/electron_mass_c2; 00107 static const double electron_Compton_length = hbarc/electron_mass_c2; 00108 static const double Bohr_radius = electron_Compton_length/fine_structure_const; 00109 00110 static const double alpha_rcl2 = fine_structure_const 00111 *classic_electr_radius 00112 *classic_electr_radius; 00113 00114 static const double twopi_mc2_rcl2 = twopi*electron_mass_c2 00115 *classic_electr_radius 00116 *classic_electr_radius; 00117 // 00118 // 00119 // 00120 static const double k_Boltzmann = 8.617343e-11 * MeV/kelvin; 00121 00122 // 00123 // 00124 // 00125 static const double STP_Temperature = 273.15*kelvin; 00126 static const double STP_Pressure = 1.*atmosphere; 00127 static const double kGasThreshold = 10.*mg/cm3; 00128 00129 // 00130 // 00131 // 00132 static const double universe_mean_density = 1.e-25*g/cm3; 00133 00134 } // namespace CLHEP 00135 00136 #ifdef ENABLE_BACKWARDS_COMPATIBILITY 00137 // backwards compatibility will be enabled ONLY in CLHEP 1.9 00138 using namespace CLHEP; 00139 #endif 00140 00141 #endif /* HEP_PHYSICAL_CONSTANTS_H */ 00142 00143 00144 00145 00146