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Random/CLHEP/Units/PhysicalConstants.h
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1// -*- C++ -*-
2// $Id: PhysicalConstants.h,v 1.4 2010/06/16 17:12:28 garren Exp $
3// ----------------------------------------------------------------------
4// HEP coherent Physical Constants
5//
6// This file has been provided by Geant4 (simulation toolkit for HEP).
7//
8// The basic units are :
9// millimeter
10// nanosecond
11// Mega electron Volt
12// positon charge
13// degree Kelvin
14// amount of substance (mole)
15// luminous intensity (candela)
16// radian
17// steradian
18//
19// Below is a non exhaustive list of Physical CONSTANTS,
20// computed in the Internal HEP System Of Units.
21//
22// Most of them are extracted from the Particle Data Book :
23// Phys. Rev. D volume 50 3-1 (1994) page 1233
24//
25// ...with a meaningful (?) name ...
26//
27// You can add your own constants.
28//
29// Author: M.Maire
30//
31// History:
32//
33// 23.02.96 Created
34// 26.03.96 Added constants for standard conditions of temperature
35// and pressure; also added Gas threshold.
36// 29.04.08 use PDG 2006 values
37// 03.11.08 use PDG 2008 values
38
39#ifndef HEP_PHYSICAL_CONSTANTS_H
40#define HEP_PHYSICAL_CONSTANTS_H
41
42#include "CLHEP/Units/defs.h"
44
45namespace CLHEP {
46
47//
48//
49//
50static const double pi = 3.14159265358979323846;
51static const double twopi = 2*pi;
52static const double halfpi = pi/2;
53static const double pi2 = pi*pi;
54
55//
56//
57//
58static const double Avogadro = 6.02214179e+23/mole;
59
60//
61// c = 299.792458 mm/ns
62// c^2 = 898.7404 (mm/ns)^2
63//
64static const double c_light = 2.99792458e+8 * m/s;
65static const double c_squared = c_light * c_light;
66
67//
68// h = 4.13566e-12 MeV*ns
69// hbar = 6.58212e-13 MeV*ns
70// hbarc = 197.32705e-12 MeV*mm
71//
72static const double h_Planck = 6.62606896e-34 * joule*s;
73static const double hbar_Planck = h_Planck/twopi;
74static const double hbarc = hbar_Planck * c_light;
75static const double hbarc_squared = hbarc * hbarc;
76
77//
78//
79//
80static const double electron_charge = - eplus; // see SystemOfUnits.h
81static const double e_squared = eplus * eplus;
82
83//
84// amu_c2 - atomic equivalent mass unit
85// - AKA, unified atomic mass unit (u)
86// amu - atomic mass unit
87//
88static const double electron_mass_c2 = 0.510998910 * MeV;
89static const double proton_mass_c2 = 938.272013 * MeV;
90static const double neutron_mass_c2 = 939.56536 * MeV;
91static const double amu_c2 = 931.494028 * MeV;
92static const double amu = amu_c2/c_squared;
93
94//
95// permeability of free space mu0 = 2.01334e-16 Mev*(ns*eplus)^2/mm
96// permittivity of free space epsil0 = 5.52636e+10 eplus^2/(MeV*mm)
97//
98static const double mu0 = 4*pi*1.e-7 * henry/m;
99static const double epsilon0 = 1./(c_squared*mu0);
100
101//
102// electromagnetic coupling = 1.43996e-12 MeV*mm/(eplus^2)
103//
104static const double elm_coupling = e_squared/(4*pi*epsilon0);
105static const double fine_structure_const = elm_coupling/hbarc;
106static const double classic_electr_radius = elm_coupling/electron_mass_c2;
107static const double electron_Compton_length = hbarc/electron_mass_c2;
108static const double Bohr_radius = electron_Compton_length/fine_structure_const;
109
110static const double alpha_rcl2 = fine_structure_const
111 *classic_electr_radius
112 *classic_electr_radius;
113
114static const double twopi_mc2_rcl2 = twopi*electron_mass_c2
115 *classic_electr_radius
116 *classic_electr_radius;
117//
118//
119//
120static const double k_Boltzmann = 8.617343e-11 * MeV/kelvin;
121
122//
123//
124//
125static const double STP_Temperature = 273.15*kelvin;
126static const double STP_Pressure = 1.*atmosphere;
127static const double kGasThreshold = 10.*mg/cm3;
128
129//
130//
131//
132static const double universe_mean_density = 1.e-25*g/cm3;
133
134} // namespace CLHEP
135
136#ifdef ENABLE_BACKWARDS_COMPATIBILITY
137// backwards compatibility will be enabled ONLY in CLHEP 1.9
138using namespace CLHEP;
139#endif
140
141#endif /* HEP_PHYSICAL_CONSTANTS_H */
142
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146