I have a Ludlum 3030P alpha beta counter. This has windows set from 70 - 700 mV and 1000 - 4000 mV but i only use it to measure Alpha smears. This instrument comes optional with detector shielding which reduces background betas. Since I'm not measuring betas does it matter that I don't have the shielding? I know that there is some beta to alpha crosstalk but would allowing this background beta in significantly impact my alpha counts?