He and 
He gas targets are sometimes used instead of the more usual
LH2 and LD2 target configuration. The helium targets are typically operated at 5.5K
and 200 psia. Clearly, the primary concern associated with LH2 and LD2
targets discussed in the previous section, namely the flammable gas
hazard, is not a problem with helium targets.
These targets are contained in a scattering chamber, so thin vacuum window eye and ear protection is still required in the vicinity of the pivot while the scattering chamber is evacuated.
The high pressure associated with these targets also presents a hazard. The target cells are pressure tested to 1.5 times the design operating pressure of 15 atm. Pressure relief valves (set to 400 psi) can be found on every section of piping that can be isolated. The primary pressure relief is a solenoid valve tied to a pressure switch, in parallel with 260 psi relief valves, a 300 psi rupture disk, and a 400 psi relief valve.
Finally, new deliveries of He are checked
for tritium contamination. The JLab radcon group has insured that the
tritium concentration in the current 3900 STP liter He inventory is
less than 15 
Ci.