Bromine nuclides

Bromine-82 has a half-life of 36 hours. A sample containing Br-82 was found to have an activity of 1.2 X 105 disintegrations/min. How many grams of Br-82 were present in the sample Assume that there were no other radioactive nuclides in the sample. 

The abundances of krypton and xenon are determined exclusively from nucleosynthesis theory. They can be interpolated from the abundances of neighboring elements based on the observation that abundances of odd-mass-number nuclides vary smoothly with increasing mass numbers (Suess and Urey, 1956). The regular behavior of the s-process also provides a constraint (see Chapter 3). In a mature -process, the relative abundances of the stable nuclides are governed by the inverse of their neutron-capture cross-sections. Isotopes with large cross-sections have low abundance because they are easily destroyed, while the abundances of those with small cross-sections build up. Thus, one can estimate the abundances of krypton and xenon from the abundances of. v-only isotopes of neighboring elements (selenium, bromine, rubidium and strontium for krypton tellurium, iodine, cesium, and barium for xenon). 

The natural abundance of Li is high enough so that any lithium salt can be used provided it is acceptable in other respects, such as solubility and freedom from unwanted nuclide production. Lithium bromide would be a poor choice since recoil-bromine atoms are also produced. Lithium carbonate is ideal in this respect but suffers from solubility difficulties. Choice of a suitable chemical form for lithium has been covered in reviews by Rowland and Wolfgang (1956) and Wolf (1960). A typical irradiation will involve a 10% (by weight) solution or slurry of an appropriate lithium salt in an organic liquid or it may be a 10% admixture with an organic solid. 

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