Search for O[-1] earthquake-like precursors: a ME$\mu $\textbf{SR MgO study }

We study O$^{\mathrm{-1}}$ earthquake-like precursor effects [1,2] by analyzing Muon-Spin-Resonance ($\mu $SR) MgO data using Maximum Entropy (ME). [3,4] Due to its presence in the Earth's crust, MgO is ideal to study these features. O$^{\mathrm{-1}}$ formation results from a 2-stage break-up in an O anion pair at high-temperature or high-pressure conditions. [2] As T increases above room temperature, a small {\%} of oxygen is predicted to produce an O$^{\mathrm{-1}}$ state. ME analysis of 100-Oe $\mu $SR data of a pure 3N-MgO single crystal produces a broad Gaussian at 1.36 MHz and a sharp Lorentzian at 1.4 MHz. The latter could be effects of extended O$^{\mathrm{-1}}$ states, as positive muons probe near O ions. There is no sharp 1.4-MHz signal observed in the $\mu $SR data of insulators Al$_{\mathrm{2}}$O$_{\mathrm{3}}$ [5] and PrBCO$_{\mathrm{6}}$ data, only the expected 100-Oe Gaussian. We have fitted ME$\mu $SR transforms of MgO to obtain an empirical description of 1.36- and 1.4- MHz peaks. Their T dependences above room temperature appear to be positive-hole effects. Relations to precursor earthquake-like O-valency effects are discussed. Research supported by ISIS-UK, LANL--DOE, SETI-NASA, SJSU {\&} AFC. 1] FT Freund, Nat Hazards Earth Sys Sci \textbf{7} (2007) 1. 2] FT Freund \textit{et al,} Phys Chem Earth \textbf{31} (2006) 389. 3] C Boekema and MC Browne, MaxEnt 2008, AIP Conf Proc {\#}1073 p260. 4] S Lee \textit{et al,} HUIC Educ, Math {\&} Eng Tech Conf, Uo HI (2013); C Boekema \textit{et al}, Bull Am Phys Soc, March 2015. 5] C Boekema \textit{et al}, Hyperfine Interactions 32 (1986) 667.