Measurement of the specific activity of ~(39)Ar in natural argon

摘要

We report on the measurement of the specific activity of ~(39)Ar in natural argon. The measurement was performed with a 2.3-1 two-phase (liquid and gas) argon drift chamber. The detector was developed by the WARP Collaboration as a prototype detector for WIMP Dark Matter searches with argon as a target. The detector was operated for more than two years at Laboratori Nazionali del Gran Sasso, Italy, at a depth of 3400 m w.e. The specific activity measured for ~(39)Ar is 1.01 ± 0.02(stat) ± 0.08(syst)Bq per kg of ~(nat)Ar.