Yes, if the lead is placed within the free path of the alpha particles, a scintillator will detect them.
Newly refined lead carries with it certain relatively short half lived isotopes which give off very low level radiation. After 100 years this signature is virtually gone.
This fact is used to detect forged oil paintings as the lead in the paints of older genuine paintings will have the isotopes vastly reduced and is a dead giveaway if modern paint is used.
Sources of bonifide older lead is often sought out by forgers and people doing sensitive measurements of radiation where the noise floor must be a couple of orders of magnitude below that of standard lead shielding.
It is a non issue here as the source is constant and can be nulled out rather effectively as a background item in long counts.
We will just never have a device that will give and honest "click" for an honest fast neutron entering a detector. It is all averaging statics for a best guess in even the finest and most expensive detectors.
Simple,plastic, scintillator detctors not specifically using proton recoil into silver activated ZnS are strictly, go, no-go detectors as mentioned earlier.
Richard Hull
Created on Wednesday, January 17, 2001 11:23 AM EDT by Richard Hull