liquid_argon  runs 2: pulse speed 766.1 m/s +- 82.2  (each run, right/left: 973/724; 870/498);  reference 840.4 m/s at 87 K, 1 atm;  ratio 0.9116
liquid_argon_wide runs 2: pulse speed 857.1 m/s +- 10.5  (each run, right/left: 862/831; 909/826);  reference 840.4 m/s at 87 K, 1 atm;  ratio 1.0198
