[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

More conversions (slight return)

Hello from the UK!

Re: Paul Vitalis' point about Sb-125.

The relationship between Bq and atoms is straightforward;

Bq =	(g x L(a) x ln(2))/(m x t)

where;

g = 	grams of active material
L(a) =	Avogadro's constant (number of atoms in one mole of material, ie
	6.022E23)
ln(2) =	natural logarithm of 2, ie 0.6931471
m =	mass number of active material
t =	half life in seconds

In addition;

N(a) =	(g x L(a))/m

where;

N(a) =	number of atoms

thus;

N(a) =	(Bq x t)/ln(2)

Since t = 1007.7 +/- 0.6 days for Sb-125 (see IAEA Tecdoc-619) we find;

1 uBq Sb-125 = 126 atoms (approx)...not a lot.

Hope that helps.

Simon Jerome
Centre for Ionising Radiation and Acoustics
National Physical Laboratory