Details of IsPhoton rejection. ----------------------------- Case 1 ------ First three selections in Kmu2Analysis applied. 15 < PTrack < 35 cut applied, then fIsLKr , fIsLAV applied in turn, see plots iosmuLKr etc. Good muon is defined as mm**2 < 0.01 GeV**2. Bool_t isPhoton = fIsLKr||fIsLAV||fIsIRC||fIsSAC||fIsSAV||fIsNewLKr ? 1 : 0; The following Table lists the numbers of events rejected for each category in the isPhoton classification above. Total events Good muons good/total rejected rejected LKr 1231 187 0.15 LAV 729 264 0.36 IRC 185 68 0.37 SAC 45 13 0.29 SAV 174 55 0.31 NewLKr 31 28 0.90 isPhoton 1780 697 0.39

Fig. 1 Data Missing mass rejected events see plots 87 -92 for each entry in the preceding Table. Case 2 ------ First three selections in Kmu2Analysis applied. 15 < PTrack < 35 cut applied. Then if ( !positron && !isEarly && fIsOneParticle && !isSegment && isRICHLikeMuon && fPTrack < 73. && muon && !isMult && isFinalBeam){ and use fIsLKr , fIsLAV etc in turn to reject photons. Good muon is defined as mm**2 < 0.01 GeV**2. Plots: iosmuLKrSel etc. Total events Good muons good/total rejected rejected LKr 160 85 0.53 LAV 218 172 0.79 IRC 31 27 0.87 SAC 12 9 0.75 SAV 29 23 0.79 NewLKr 15 14 0.93 isPhoton 372 278 0.75

Fig. 3 Data Missing mass rejected events see plots 139 -147 that correspond to the above table. A good muon missing mass peak is evident in all plots.