Radioactivity in Silver Induced by Fast Neutrons

Radioactive silver, Ag¹¹², has been produced by fast neutron bombardment of Cd¹¹² and In¹¹⁵. A half-life period of 3.2 hours is observed with the upper limit of the electron beta-ray spectrum at 2.2 Mev. Gamma-rays are also emitted, the number per beta-ray is about four. The radioactive silver isomer, Ag¹⁰⁶, produced by fast neutron bombardment of Ag¹⁰⁷, has a positron beta-ray spectrum upper limit of 1.9 Mev and an electron beta-ray spectrum upper limit of 1.3 Mev. The half-life periods are respectively 24.5 min. and 8.2 days. The former emits no gamma-rays other than the annihilation radiation. The latter emits a complex gamma-ray spectrum. The number of gamma-rays per beta-ray is about 35. Nuclear K electron capture is offered to explain this anomalously high gamma to beta ratio. A total of twenty nuclear reactions all leading to the production of radioactive silver have been observed.