670 



TABLE 727.— METHODS OF PRODUCING ELEMENTS BEYOND URANIUM 228 



The heavier elements, Np, Pu, Am, Cm, Bk, and Cf may be produced by artificial trans- 

 formation of U, followed by radioactive breakdown. A few examples follow : 



» 2 U 238 + on l -> u ,U 2:,,, + 7 



^U^-^^Np 28 ' + /3"(23 min) 

 ^Np 2 " — » „ 4 Pu 2J " + /3"(2.3 days) 



«U" + oil 1 -» ■bU 2 * 7 + o>« 1 + oh 1 



„U M7 -^ !!2 Np^ +/3-(6.8d) 



..U 238 + ,H 2 _» U3 Np 238 + „ M l + on 1 



, : ,Np 2 s — » wPu"* + j8"(2.0 d) 

 „U 2 * + .He 4 _>..Pu* , \ii I 



M Pu i "^ „ i Am"' + /3'(~10 yr) 



For quantity production : 

 M Pu 23u + on 1 _» M Pu 240 + 7 



M Pu 2,0 + »n , ->»Pu ! " + 7 

 94 Pu 2J1 -> u ,-Am 2, ' + r 

 94PU 230 + 2 He 4 _» ,,,Cm 242 + o" 1 



or ooCm 210 + gft 1 + ow 1 + o»' 



For quantity production : 



» 5 Am 241 + on 1 -» „ 5 Am ffi + 7 



u.Am 212 * -> M Cm M + p- 

 »oAm 241 4- 2 He 4 _» „;Bk 2 ' 3 4- » l 4- on 1 

 » Cm 242 + 2 He 4 -» a.Cf 1 " 4 4- on 1 + on 1 



2 -' ,, G. T. Seaborg, private communication. 

 * Sixteen-hour + 100-year isomers. 



TABLE 728.— PILE YIELDS OF SOME ISOTOPES* 



Calculated for 10 liters of material exposed to 10'° neutrons cm" 3 sec" 1 



* Revised by J. L. Rhodes. For reference, see footnote 226, p. 667. 



SMITHSONIAN PHYSICAL TABLES 



