3He–Ne–CH4 Mixtures in a Proportional Counter for Thermal Neutrons

Some mixtures of 3He, neon, and methane have been investigated and found to have advantages as fillings for proportional counters to detect thermal neutrons. Recipes which were satisfactory in a counter with a 3.5-in. diam include 15.7 psi of 3He+17 psi of neon+14 psi of methane and 1.0 psi of 3He+25 psi of neon+8 psi of methane.