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UN/CEFACT


United Nations Centre for Trade Facilitation and Electronic Business
 
Trade Facilitation Recommendation N° 20

 

Units of Measure: Code elements listed by quantities

 

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Quantity
Level
Cat.
Use
Id.
Name
Convesion factors to SI units (1 unit equals)
Represen.
Symbol
Cross
ref.
Atomic and Nuclear Physics
proton number, atomic number 1   one   1 692
neutron number 1   one   1 693
nucleon number, mass number 1   one   1 694
mass of atom (of a nuclide x), 1   kilogram   kg 695
nuclidic mass 1   unified atomic mass unit  1,660 540 2 x 10-27 kg u 696
unified atomic mass constant            
(rest) mass of electron 1   one   1 698
(rest) mass of proton            
(rest) mass of neutron            
mass excess 1   kilogram   kg 701
mass defect 1   unified atomic mass unit 1,660 540 2 x 10-27 kg u 702
relative mass excess 1   one   1 703
relative mass defect            
packing fraction 1   one   1 705
binding fraction            
elementary charge 1   coulomb   C 707
Planck constant 1   joule second   J.s 708
Bohr radius 1   metre   m 709
  1   ångström 10-10m (exactly) Å 710
Rydberg constant 1   reciprocal metre   m 711
Hartree energy 1   joule   J 712
magnetic moment of partical or nucleus 1   ampere square metre   A.m² 713
Bohr magneton            
nuclear magneton            
gyromagnetic coefficient,
(gyromagnetic ratio)
1   ampere square metre per joule second   A.m²/(J.s) 716
g-factor of atom or electron 1   one   1 717
g-factor of nucleus or nuclear particle            
Larmor angular frequency 1   reciprocal second   s 719
nuclear precession 1   radian per second   rad/s 720
cyclotron angular frequency            
nuclear quadrupole moment 1   square metre   m² 722
nuclear radius 1   metre   m 723
electron radius            
Compton wavelength            
orbital angular momentum quantum number 1   one   1 726
spin angular momentum quantum number 1   one   1 727
total angular momentum quantum number 1   one   1 728
nuclear spin quantum number 1   one   1 729
hyperfine structure quantum number 1   one   1 730
principle quantum number 1   one   1 731
magnetic quantum number 1   one   1 732
fine structure constant 1   one   1 733
mean life 1   second   s 734
half life            
level width 1   joule   J 736
alpha disintegration energy            
maximum beta partical energy 1   electronvolt 1,602 177 33 x 10-19 J eV 738
beta disintegration energy            
internal conversion factor 1   one   1 740
activity 2   curie 3,7 x 10-10 Bq (exactly) Ci 741
  2S   millicurie   mCi 742
  2S   microcurie   µCi 743
activity 2S   kilocurie   kCi 744
  1   becquerel   Bq 745
  1M   gigabecquerel   GBq 746
  1S   kilobecquerel   kBy 747
  1S   megabecquerel   MBq 748
specific activity in a sample 2   curie per kilogram   Ci/kg 749
  1   becquerel per kilogram   Bq/kg 750
  1S   megabecquerel per kilogram   MBq/kg 751
  1S   kilobecquerel per kilogram   kBq/kg 752
volumic activity, 1   becquerel per metre cubed   Bq/m³ 753
activity concentration            
decay constant, 1   reciprocal second   s 755
disintegration constant            

 

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