  The Jiangmen Underground Neutrino Observatory (JUNO) is a 20 kton liquid
scintillator detector currently being built in a dedicated underground
laboratory in China. It is a multi-purpose underground experiment with a
physics program including neutrino mass hierarchy determination, precision
measurement of neutrino oscillation parameters, measurement of solar,
atmospheric, geo-neutrinos and other important neutrino physics searches.
Electron anti-neutrinos are detected via the inverse beta decay by measuring
the correlated positron and neutron signals. In this detection channel cosmic
ray muon induced radioactive isotopes are the main background, especially those
connected to cosmogenic backgrounds ($^{9}$Li/$^{8}$He and fast neutrons). They
are predominantly produced by showing muons which account for about 10\% of all
muons. Considering that the $^{9}$Li/$^{8}$He background is correlated with the
parent muon in time and space, the vertex reconstruction of showers along the
muon track is helpful to reject the backgrounds of $^{9}$Li/$^{8}$He and other
isotopes. Based on the waveform simulation analysis, we know that the
multi-peaks in waveform output by PMTs are mainly caused by these showers.
Waveform analysis of muon events and preliminary results of shower vertex
reconstruction based on detector simulation have been studied.
