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PhysicalConstants.py
Go to the documentation of this file.
1 # File: AthenaCommon/share/PhysicalConstants.py
2 # Author: Wim Lavrijsen (LBNL, WLavrijsen@lbl.gov)
3 # Created: 01/21/04
4 # Last: 10/15/04
5
6 # This script is a direct adaptation of CLHEP/Units/PhysicalConstants.h
7 # and the following is the originial CLHEP comment:
8 #
9 # -----
10 # This file has been provided by Geant4 (simulation toolkit for HEP).
11 #
12 # The basic units are :
13 # millimeter
14 # nanosecond
15 # Mega electron Volt
16 # positon charge
17 # degree Kelvin
18 # amount of substance (mole)
19 # luminous intensity (candela)
20 # radian
21 # steradian
22 #
23 # Below is a non exhaustive list of Physical CONSTANTS,
24 # computed in the Internal HEP System Of Units.
25 #
26 # Most of them are extracted from the Particle Data Book :
27 # Phys. Rev. D volume 50 3-1 (1994) page 1233
28 #
29 # ...with a meaningful (?) name ...
30 #
31 # You can add your own constants.
32 #
33 # Author: M.Maire
34 #
35 # History:
36 #
37 # 23.02.96 Created
38 # 26.03.96 Added constants for standard conditions of temperature
39 # and pressure; also added Gas threshold.
40 # -----
41
42 from GaudiKernel.SystemOfUnits import *
43
44 #
45 #
46 #
47 pi = 3.14159265358979323846
48 twopi = 2*pi
49 halfpi = pi/2
50 pi2 = pi*pi
51
52 #
53 #
54 #
55 Avogadro = 6.0221367e+23/mole
56
57 #
58 # c = 299.792458 mm/ns
59 # c^2 = 898.7404 (mm/ns)^2
60 #
61 c_light = 2.99792458e+8 * m/s
62 c_squared = c_light * c_light
63
64 #
65 # h = 4.13566e-12 MeV*ns
66 # hbar = 6.58212e-13 MeV*ns
67 # hbarc = 197.32705e-12 MeV*mm
68 #
69 h_Planck = 6.6260755e-34 * joule*s
70 hbar_Planck = h_Planck/twopi
71 hbarc = hbar_Planck * c_light
72 hbarc_squared = hbarc * hbarc
73
74 #
75 #
76 #
77 electron_charge = - eplus # see SystemOfUnits.h
78 e_squared = eplus * eplus
79
80 #
81 # amu_c2 - atomic equivalent mass unit
82 # amu - atomic mass unit
83 #
84 electron_mass_c2 = 0.51099906 * MeV
85 proton_mass_c2 = 938.27231 * MeV
86 neutron_mass_c2 = 939.56563 * MeV
87 amu_c2 = 931.49432 * MeV
88 amu = amu_c2/c_squared
89
90 #
91 # permeability of free space mu0 = 2.01334e-16 Mev*(ns*eplus)^2/mm
92 # permittivity of free space epsil0 = 5.52636e+10 eplus^2/(MeV*mm)
93 #
94 mu0 = 4*pi*1.e-7 * henry/m
95 epsilon0 = 1./(c_squared*mu0)
96
97 #
98 # electromagnetic coupling = 1.43996e-12 MeV*mm/(eplus^2)
99 #
100 elm_coupling = e_squared/(4*pi*epsilon0)
101 fine_structure_const = elm_coupling/hbarc
102 classic_electr_radius = elm_coupling/electron_mass_c2
103 electron_Compton_length = hbarc/electron_mass_c2
104 Bohr_radius = electron_Compton_length/fine_structure_const
105
106 alpha_rcl2 = fine_structure_const*classic_electr_radius*classic_electr_radius
107
108 twopi_mc2_rcl2 = twopi*electron_mass_c2*classic_electr_radius*classic_electr_radius
109 #
110 #
111 #
112 k_Boltzmann = 8.617385e-11 * MeV/kelvin
113
114 #
115 #
116 #
117 STP_Temperature = 273.15*kelvin
118 STP_Pressure = 1.*atmosphere
119 kGasThreshold = 10.*mg/cm3
120
121 #
122 #
123 #
124 universe_mean_density = 1.e-25*g/cm3