6.6.1 Absolute coincident particle-gamma yields

[LPGaffney]

There is some confusion in this section with regards to the solid angle fraction when calculating absolute gamma-ray yields. It seems to imply that the final term in equation 6.65 should be a fraction of 4*pi, i.e. 0.5 for 50% of solid angle, but I believe that this should actually be the true solid angle in units of steradians as the units imply.

Therefore, the explanation which follows (top of page 94) is very confusing and in my opinion, wrong. I spent some time looking for a factor of ~10 in my calculations recently, when I should have included this 4*pi to account for the 100% solid angle which is assumed in my efficiency calculations. With the factor of 4*pi included, my calculations are correct.

I hope this isn't just my misunderstanding of what is already written, but if so, I still believe it can be better written to prevent future confusion.

Best wishes,
Liam