Phys ica l Backgro und
3
Table 1.1. C haracteri stics of radi oisotopes used in hydrobio logy
R adioisoto pe
E mitted
E nergy of
H alf-life
Commo n
particle type
radi ation (MEV )
che mical forms
3H
13
0.01 8
12 years
H 2; organic
compounds
14C
13
0.155
5730 years
Na2C03;
NaH C 0 3; CH 4-;
orga nic
compounds
32 p
13
1.71
14.3 d ays
H 3P 04; organic
compounds
33p
13
0.25
25.5 d ays
"
, "s
13
0.1 7
87.4 d ays
Na2S04; Na2S20 j;
Na2Sx9H20
45Ca
13
0.25
164 days
CaCh
" Fe
X-ray Auger
0.006
2.7 years
FeCh
e lectro ns
57CO
y
0.20
271 days
CoCh
100
75
50
25
E, Mev
0
0
0,005
0,01
0,015
0,02
100
75
50
Emax=0.156
25
, E, Mev
0,05
0,1
0,15
0,2
Fig. 1.lA,B. Beta spectra of A tritium COH ) and B 14C-carbo n. I Re lative intensity of
radi atio n (e.g., proba bility of emissio n of the particles of that energy); E energy of
p articles emitted (energy of r adiation); Em"x maximal energy of radiatio n