[povik]

To nitpick here: You need less than kilogram of electrons to screen a kilogram of protons (roughly 2 grams it seems)

[cbkeller]

Quite true! I thought about saying “kg of positrons and kg of electrons” or such so that the mass/charge ratio would be more equivalent.

[jschwartzi]

You're actually looking for a mol of electrons and a mol of protons.