Decay scheme and sources

23-875-keV decay [1, 2] from the first excited state. The precursor is metastable Sn which has a half-life of250 days and can be prepared in adequate activity by neutron capture in isotopically enriched Sn. Because the capture reaction also results in considerable production of Sn in the ground state the preparation is not carrier-free in terms of the resonant isotope. The 23-88-keV transition is a f i magnetic dipole transition and as such may 

5-13 [4]) but the basic decay scheme is uncomplicated and efficient counting can be achieved. The 65-66-keV 7-ray is even more strongly converted and is consequently weak in intensity the resulting 25 04- and 25-27-keV X-rays can 

The nuclear parameters determining the probability of a recoilless event are closely matched to those of Fe, although the preponderance of organo-metallic compounds in tin chemistry has meant that most measurements are made at liquid nitrogen temperature because of the low effective Debye temperature of these materials. It is not, however, difficult to obtain a source with an adequate recoilless fraction for use at room temperature. 

As already discussed in Chapter 12, it is not unusual for anomalous charge states to be produced following nuclear transitions involving electron 

An alternative source preparation which has not been widely adopted is the Sn( /, ) Sb reaction using 10-MeV deuterons in a cyclotron [6]. The Sb decays by electron capture with a 38-hour half-life to the 23-88-keV level as shown in Fig. 14.1. 25-keV K-X-rays are also produced in the electron-capture process, so that in most respects the decay is similar to the ii9ffl5 transition. 

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