The β-ray spectra of Ni
63, Zn
63, Zn
65, Zn
69 (57 m), Zn
69 (13.8 h), Ga
68, Ga
70, Ga
72, Ge
71, Ge
75 and Ge
77 have been investigated, by measuring the curvature of the tracks in a cloud chamber situated in a known magnetic field. The upper limit derived from K-U plots are summarised as follows.
Ni
63 2.5h e
- 1.65 × 10
6 eV 0.67 × 10
6 eV
Zn
63 35m e
+ 1.92 × 10
6 eV
Zn
65 210d e
+ 0.37 × 10
6 eV 0.19 × 10
6 eV
Zn
69 57m e
- 0.99 × 10
6 eV
Zn
69 13.8h e
- 0.99 × 10
6 eV
Ga
68 66m e
+ 1.37 × 10
6 eV
Ga
70 20m e
- 1.68 × 10
6 eV
Ga
72 14h e
- 1.71 × 10
6 eV
Ge
71 26h e
+ 1.15 × 10
6 eV
Ge
75 81m e
- 1.10 × 10
6 eV
Ge
77 8h e
- 1.92 × 10
6 eV
From the consideration of energy balance, the minimum neutron energies to produce neutron loss processes-, for Cu
62, Zn
63 and Ga
68 are estimated roughly to be 12.7, 9.8 and 9.0 MeV respectively, which are in good agreement with the values reported by one of the authors except the last case.
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