Chapter Head
Table of Contents
Glossary

Useful Quantities in Nuclear Science

atomic mass unit (u) mass 12C 1.6605402x10-27 kg
electric charge (coulomb) e 1.60217733x10-19 C
speed of light (vacuum) c 299792458 m/s (exact)
Particle Mass
Charge
Half-life
  (in u)
(in electron charge, e)
(in seconds)
proton, p 1.007276
+1
stable
neutron, n 1.008665
0
624
electron, e or e- 0.000549
-1
stable
neutrino, > 0
0
stable*
antiproton, 1.007276
-1
stable
antineutron, 1.008665
0
624
positron, e+ 0.000549
+1
stable
antineutrino, > 0
0
stable*
muon, m± 0.10565
+1, -1
3.17x10-6
pion, p± 0.14
+1, -1
3.76x10-8
pion, p0 0.14
0
6.63x10-17
photon, g 0
0
stable
gluon, g 0
0
 
up quark, u approximately 0.005
+2/3
 
down quark, d approximately 0.01
-1/3
 
strange quark, s 0.1 to 0.3
-1/3
 
charm quark, c 1.0 to 1.6
+2/3
 
bottom quark, b 4.1 to 4.5
-1/3
 
top quark, t 180 ± 12
+2/3
 
1H atom 1.007825
0
stable
2H nucleus 2.013553
+1
stable
2H atom 2.014102
0
stable
3H nucleus 3.015500
+1
3.88x108
3H atom 3.016049
0
3.88x108
3He nucleus 3.014932
+2
stable
3He atom 3.016029
0
stable
4He nucleus 4.001506
+2
stable
4He atom 4.002603
0
stable
12C atom 12.000000
0
stable
238U atom 238.050785
0
1.41x1017

Antiparticles are assumed to have same half-life as particles.
*Neutrinos (antineutrinos) can change into an other one of the same type.

From the Review of Particle Properties, R. M. Barnett et al., Physical Review D54, 1 (1996).

International System of Units (SI)–SI prefixes

value name symbol
10-24 yocto y
10-21 zepto z
10-18 atto a
10-15 femto f
10-12 pico p
10-9 nano n
10-6 micro m
10-3 milli m
10-2 centi c
10-1 deci d
10 deca da
102 hecto h
103 kilo k
106 mega M
109 giga G
1012 tera T
1015 peta P
1018 exa E
1021 zetta Z
1024 yotta Y

Example of a Branching Ratio

226Ac Æ Th + e- + 83%
226Ac + e Æ 226Fr + 17%
226Ac Æ 222Fr + 4He 0.006%

  last updated: August 9, 2000 webmaster