Letter | Published:

Nuclear Isomeric Transitions of Short Periods

Nature volume 162, pages 186187 (31 July 1948) | Download Citation



THE elements copper, molybdenum, silver, cadmium, indium and lead have been irradiated by a pulsed beam of X-rays, activity ascribable to metastable states being sought in the intervals between pulses. The electrons producing the X-ray pulses had energies up to 1.05 MeV., the pulse width was 5 µsec., repetition frequency 200 per sec. and mean current 15 µamp.; the mean current during the pulse was thus approximately 15 m.amp. The elements were irradiated within Geiger–Müller counters, counts between pulses being displayed on an oscillograph with time-base triggered by the pulses. No evidence of activity was obtained. Periods greater than 100µsec. could have been detected. Some details are given below of the experimental arrangements whereby a particular spurious effect can be eliminated, since these may be of interest in similar studies where more energetic X-rays are available.

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    , , and , Nature, 157, 840 (1946).

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    , and , Phys. Rev., 55, 245 (1939).

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    , and , Phys. Rev., 57, 338 (L) (1940).

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    , Phys. Rev., 67, 92 (1945).

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    See, for example, , and , Phys. Rev., 70, 569 (1946); 71, 380 (1947).

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  1. School of Physics, University of Sydney. March 30.

    • P. B. TREACY


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