Figure 1. Long-lasting flux enhancement measured by ORTEC spectrometer (blue curve); near-surface electric field measured by the electric mill EFM-100 located on the roof of the MAKET experimental hall. By red arrows, the time spans are shown corresponding to the frames a=d in Fig 2 (besides time span N 5) and shown in Table 1.
In Fig. 2 (a-d) we show energy spectra of 4 successive episodes of very long flux enhancement. Each episode covered 1-hour time; in episodes the spectral line of 214Bi isotope (609 keV) is most abundant; another Bismuth isotope 214Bi (1.12 MeV) also produces smaller peaks.