Hello, I'm working on a lab report centered on Beta decay and I am confused how absorber thickness is obtained. We used varying thickness aluminum plates spaced 2cm from a Sr-90 source taking measurements with an ST350 counter/GM tube/software. By my understanding the absorber thickness [g or mg/cm^2] is calculated by getting the product of the material's density and thickness. Density of Material x Thickness Is this correct? The lab asks a question regarding fluctuating count values higher than 1400 mg/cm^2 thickness however my maximum thickness is 857 mg/cm^2. Thank you.