Tl-208 decays through a beta emission and has a half-life of 3.05 minutes. Besides the beta emission, there are several gamma rays associated with the decay and these gamma emissions occur at different fractions.

Table 1. Thallium-208 gamma emission data

Energy of emission (MeV)	Fraction of decays
2.6146	0.9979
0.5831	0.8582
0.5108	0.2155
0.8604	0.1197

Table 2. Beryllium data

Nuclear data	Mass Excess (MeV)
Be-9	11.348
Be-8	4.942
n (nucleons)	8.071

a. Using the information in Table 1 and Table 2, and using 100% Be-9 as the target, which of the above gamma emissions will produce a photoneutron?

b. Using the same radio-isotope and target, if the material is in the 100% Be sphere, how many neutrons will a Tl-208 source with the activity of 40 GBq produce?

c. Instead of Tl-208, you substitute 10 Gbq of Na-24 and place this in the sphere. How many neutrons will be produced by each of the Na-24 gamma emissions if the neutron yield is 3.4E5 n/s for 10 Gbq. The Na-24 gamma-ray emissions are 1.3685 MeV (100%) and 2.7540 (99.863%).