Methods for detecting events in double-phase argon chambers

Abstract

Multichannel wire gas electron multipliers in combination with pin anodes are proposed for detection of events in the gas phase of a double-phase argon chamber. Hydrogen with a concentration of 10 vol % is added to argon to eliminate feedbacks by photons emitted by excited argon molecules in avalanche development processes while detecting events in the argon gas. A maximum electron multiplication coefficient of ∼300 has been obtained for the multichannel wire gas electron multipliers with a 1-mm gap used to detect α particles in the Ar + 10% H₂ mixture at a pressure of 1 atm (abs.). When a pin anode is used, the maximum electron multiplication factor is ∼2.5 × 10⁵ for α particles and 3 × 10⁶ for β particles (⁶³Ni). It has been experimentally shown that adding H₂ with a concentration of 100 ppm to liquid argon has no effect on the singlet component of the scintillation signal in the liquid argon and reduces the emission efficiency relative to the pure argon gas phase only slightly (by 20%).