linac energy

Hi all, this is my first time posting.

This may seem too vauge but could a 2m long linac accelerating electrons (with electron gun as source) achive 1.5MeV? I.e. Could it make positrons via pair production? (0.511MeV For electron same for positron plus a litle extra to be safe) asuming it uses quadropole and sextupole magnets (copper) liquid nitrogen cooled. Electrostaticly acelerated via muliple staged electrodes (max voltage=~100 000v). Thanx to you geniuses in advace