Thickness Vs. for 511 KeV.

Table 2: Thickness Vs. $l n \frac{I_{o}}{I}$ for 511 KeV.

I_o= 87799
Source	Energy in KeV	Absorber	Thickness in cm	I	IoI	$l n \frac{I_{o}}{I}$
²²Na	511	Zinc	0.04	84827	1.0350	0.0344
			0.08	81796	1.0733	0.0708
			0.12	79100	1.1099	0.1043