ME- μSR MgO study: search for O[-1] earthquake-like precursors

We analyze O-¹ earthquake-like precursor effects by studying the μSR signals of MgO using Muon-Spin Resonance and Maximum Entropy (ME). Due to its abundance in the earth crust, MgO is ideal for studying these features: O-¹ (or positive hole) formation results from a break in an oxygen anion pair under elevated temperature or high pressure conditions. For a 3N-MgO single crystal above RT, a small percentage (<1%) is predicted to be in an O-¹ state, instead of typical O-² ions. ME analysis of transverse field (100 Oe) MgO data show asymmetrical μSR peaks at ~ 1.4 MHz. Small T-dependent deviations from a Lorentzian (Lor) signal could be effects of O-¹ states in MgO. We have fitted ME transforms with three Lorentzians to obtain a reasonable description of the 1.4-MHz peak. The T dependences of this 3-Lor set and their B-field dependences at 17°C are reported and discussed, and their relation to precursor earthquake-like O-valency effects. Research supported by RSCA-SJSU, SETI, WiSE-SJSU and AFC San Jose.