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IV TABLE OF ISOTOPES Isotope As A.1 As 70 As 71 As 72 As 73 As 74 As' As 76 As 77 Half life Some methods of preparation Principal types of decay Energy of principal Energy of principal P-radiations MeV v-radiations, MeV (with percentage of 7m Ge70(p, 3n) ff total y"s where shown) 15m Ge70(p, 2n) E.C. (~3%) jff*' (--97%) 2.9 52m Ge70(d. 2n) E.G. (3%) d. Se70 #*' (10%) 1.44 E.C. (5.3%) B* (74.7%) 2.144 E.G. (0.18%) 8* (6.1%) 2.89 y 1.04 62h Ge70(d,n) 71 fi~ (3%) 0.25 d. Se71 (? (6%) 0.79 E.G. (58%) 8* (33%) 0.813 y 0.175 26h Ga69(a, n) E.G. (21. 2%) Ge72(p, n) fi* (3.6%) Ge72(d, 2n) B* (56.2%) 2.50 d. Se72 B*~ (19%) 3.34 y 0.630 (8) y 0.835 (75) 76d Ge72(d, n) E.C. d. Se73 y 0.0135(e/y> 13OO) 0.054(e/y ~ 5) [N.B. These y's are from decay of 17. 5d Ga71(a, n) E.G. « 1%) Ge73m, tv4 0.33S]. Ge74(d, 2n) ff (< 0.1%) *J A Ge74(p, n) E.C. (38%) As75(n, 2n) & (25%) 0.92 E.C. (2.2%) ff (2.8%) 1.53 ff (16%) 0.69 /T (16%) 1.36 y 0.596 (80) 100% natural abundance y 0.635(20) 26.5h As75(n, y) fT (5 1%) As75(d. p) Br79 (n, a) Se76 (n, p) fT (6.9%) fT (35%) ff (53%) 1.748 2.405 2.965 y 0.559 (71) y 0.658 (6) y 1.127 (16) 39h Ge76 (d, n) 8~ (2.5%) fission 77 /S~ (97.5%) 0.69 d. Ge77 y (weak) 0.086 (4) y (weak) 0.160 (7) y (weak) 0.246 (67) y (weak) 0.524 (22)

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,..-... Some methods of Principal types Energy of principal Energy of principal isotope Halt lite preparation of decay jS-radiations MeV y-radiations MeV twith percentage of total y's where shown) As78 91m Br81(n, a) 0~ (30%) 1.4 Se78(n, p) ff (70%) 4.1 fission d. Ge78 y 0.270 y 0.610 Y 0.800 y 1.280 y 2.680 As79 9m Se80(y, p) /3~ (5%) Se80(n.pn) ff (95%) 2.15 Se82(d, an) A.80 15.35 Se80(n, p) £~ (0.8%) 0~(4.3%) 3.7 r5~(3.5%) 4.1 £~(1.7%) 4.2 0~ (1.4%) 4.5 ft~ (32%) 5.4 ft~ (56%) 6.0 y 0.66 As81 31s Se82(y, p) /S~ (100%) 3.8

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For further information on the radiations of the arsenic isotopes see:- B. S. Dzhelepov and L. K. Peker "Decay Schemes of radioactive isotopes", Pergamon Press, Oxford, 1961. D. Strominger, J. M. Hollander and G. T. Seaborg, Revs. Mod. Phys. 30.2 Part II 1958. 1960 Nuclear Data Tables NAS-NRC Washington 1960. 1959 Nuclear Data Tables NAS-NRC Washington 1959. Nuclear Level Schemes A = 40 to A = 92 NAS-NRC Washington 1955.