662 



TABLE 719.— ATOMIC WEIGHTS AND OTHER CHARACTERISTICS OF ISOTOPES 



(continued) 



Quadrupole 

 moment t " 



(+2.8) 

 +2.6 



+ -5 



Part 3. — Thallium to curium (1950) I 



The masses have been derived as outlined by Stern.* The mass of the a-particle is assumed 

 to be 4.00389 mass units and the mass of Pb is 206.04519 mass units. The masses of thallium, 

 lead, and bismuth isotopes are determined from the following neutron binding energies (in Mev) : 



Tl"* 6.52±0.03 



Tl** 7.48±0.15 



Tl** 6.30±0.03 



Pb 206 .... 8.15 ±0.05 

 Pb 207 .... 6.719±0.016 

 Pb 208 .... 7.38 ±0.008 



Pb 200 .... 3.87±0.05 



Bi 200 7.44±0.05 



Bi 210 4.62±0.015 



The decay energies are taken from a paper by Wapstra ' except for two corrections. The 

 decay energy of Ra 223 is taken to be 170 Kev higher than that given by Wapstra as was assumed 

 by Stern. Also, it is assumed that the decay of Ra 225 is 700 Kev, and the masses based on this 

 assumption are in parentheses. A few other disintegration energies not given by Wapstra were 

 taken from Perlman, et al/ 



Z 



81 



Tl 



82 Pb 



83 Bi 



(continued) 



SMITHSONIAN PHYSICAL TABLES 



