Appendix 8, Decay of Cerium-144
Description:
As part of an earlier program of investigation in this laboratory, studies were made of the gamma ray spectrum and the beta ray spectrum of cerium-144. In the present work, seme coincidence studies were made on one of the beta groups appearing in the cerium-144 decay and on the gamma rays appearing in the deexcitations from the energy levels of praseodymium-144. Sources of cerium-144 were prepared frcm carrier free radioactive cerium-144 as supplied by the Oak Ridge National Laboratory. The sample material was more than two years old at the time of preparation of sources. No additional chemical purification was attempted. Sources for use in the beta crystal spectrometer were mounted on thin Formvar film on spectrometer ring mounts. The gamma ray spectrum of cerium-144 in the energy range 20 kev to 180 kev is shown in Figure 1. This spectrum was determined using a 2-inch by 2-inch NaI(Tl) crystal. The pulse spectrum was analyzed by a Radiation Instrument Development Laboratory (RIDL) 200 channel analyzer. The spectrum gives clear evidence of gamma ray peaks at 34 {+-} 3 kev and 134 {+-} 2 kev. A rather broad peak at 80 kev is observed. An indication of a gamma ray group of energy near 100 kev is also shown. The resolution of the detecting assembly was 9.8 percent at 662 kev. The uncorrected relative intensities of the three groups of 34, 80 and 134 kev are 95, 35, and 100, respectively. These intensities are for the gamma radiation exclusive of internal conversion. Gamma-gamma coincidence measurements were made using two of the 2-inch by 2-inch sodium iodide crystals placed at 90 degrees to one another, Ganmma radiation of a particular energy was selected by means of a single channel analyzer and the 200 channel analyzer was used to analyze any coincident pulses …
Date:
June 1, 1960
Creator:
Sathoff, H. J. & Azuma, T.
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