Search for metastable muonic 2s atomic states

An experimental search was made in low Z gas for the two-photon deexcitation of metastable 2s muonic states. Four intrinsic germanium (Ge) photon detectors were used to measure energetic photons (20-200 keV) occurring within 500 nsec of muon stops in various target gases. Time and energy information from photon events which were time coincident in two detectors were recorded on magnetic tape for subsequent analysis. Information from single photon events were recorded as histograms. N2, O2, and (B2H6) at pressures between 0.5 and 4.0 atmospheres were used as target gases in the search for two-photon deexcitation. Upper limits for formation of metastable 2s muonic states range from (1.9 +- 4.3) x 10-3 to (0. +- 7.2) x 10-4 of all muon stops. The single photon Lyman intensity ratios were compared to predictions made by a cascade computer program which used the electron refill time as a variable parameter. The observed intensity ratios in nitrogen gas agreed with predictions of a model which specified refill times of about 10-11 sec at the pressure used