Nuclear gamma-ray lines

Nuclear gamma-ray lines constitute the most genuine diagnostic tool of nuclear astrophysics, since they allow for an unambiguous identification of isotopic species. Gamma-ray lines produced by the radioactive decay of unstable nuclei carry unique information related to the decay time scale, and provide us with unprecedented data about nucleosynthesis processes and activity. The annihilation of positrons leads to characteristic gamma-ray emission which carries information about the annihilation environment and the galactic magnetic field. Interaction of energetic particles with ambient matter populates excited nuclear levels, leading to gamma-ray lines that inform about the energetic particle spectrum and composition, the interstellar medium composition, and the gas-to-dust ratio.
The following table shows a compilation of the most important gamma-ray lines originating from radioactive isotopes. Lines marked in red have already been observed by gamma-ray telescopes. A tentative detection of the 1173 and 1333 keV gamma-ray lines from 60Fe has been reported using observations of the RHESSI telescope, yet still awaits confirmation by SPI/INTEGRAL. Click on the isotopes to learn more about the astrophysics involved.

Isotope
Lifetime
Line energy (keV)
57Ni
2.14 d
1378
56Ni
8.5 d
158 (98.80%), 750 (49.89%), 812 (87.4%)
59Fe
64.2 d
1099 (56.5%), 1292 (43.2%)
7Be
77 d
478
56Co
112 d
812, 847 (100%), 1238(100%)
65Zn
169 d
1116
54Mn
216 d
835
57Co
392 d
122 (86%), 136(11%)
22Na
3.76 yr
1275
60Co
7.61 yr
1173 (99.9%), 1333 (99.98%)
44Ti 
79 yr
68, 78, 1157
26Al
106 yr
1809
60Fe
2.2 * 106 yr
59, 1173, 1333
 

If you want to learn more about gamma-ray telescopes then click here.


Jürgen Knödlseder, CESR, 28-11-2003