  The Ultra High Energy Cosmic Ray (UHECR), by UHE neutrino-relic neutrino--Z
showering in Hot Dark Halos (HDM), shows an energy spectra, an anisotropy
following the relic neutrino masses and clustering in dark halo. The lighter
are the relic neutrinos masses, the higher their corresponding Z resonance
energy peaks. A twin light neutrino mass splitting may reflect into a twin Z
resonance and a complex UHECR spectra modulation as a twin bump at at highest
GZK energy cut-off. Each possible neutrino mass associates a characteristic
dark halo size (galactic, local, super cluster) and its anisotropy due to our
peculiar position within that dark matter distribution. The expected Z or WW,ZZ
showering into proton-anti proton and neutron-anti neutron might correspond to
peculiar clustering in observed UHECR at 10^{19}, 2 10^{19}, 4 10^{19} eV. A
neutrino light HDM halo around a Mpc will allow to the UHECR
neutron--anti-neutron secondary component at E_n> 10^{20} eV (due to Z decay)
to arise playing a role comparable with the charged p-bar{p} ones. Their
un-deflected n-bar{n} flight is shorter leading to a prompt and hard UHECR
trace pointing toward the original UHECR source direction. The direct
proton-antiproton pairs are split and spread by random magnetic fields into a
more diluted and smeared and lower energy UHECR signal around the original
source direction. Additional prompt TeVs signals by synchrotron radiation of
electro-magnetic Z showering must also occur solving the Infrared-TeV cut-off.
The observed hard doublet and triplets spectra, their time and space clustering
already favour the rising key role of UHECR n-bar n secondaries originated by
neutrino-Z tail shower.
