  In view of the safe operation of the quadrupoles in the luminosity upgrade of
the LHC accelerator, the response of the copper stabilizer at low temperatures
to the various high energy radiation sources is of primary importance. The
present study takes into account the expected high energy spectrum of the
simultaneous radiation by neutrons, protons, pions, electrons and photons,
calculated using the FLUKA code by F. Cerutti (CERN) as well as on literature
values. It was found that proton irradiation causes a considerably higher
damage than neutron irradiation: in spite of a 3.8% proton fraction, the
measured damage is of the order of 20%, which fits with the calculations of N.
Mokhov (Fermilab) on the contribution of protons to the dpa. The same
calculations indicate that the total effect of protons, pions and electrons is
at least as high as that of neutrons. Since recent neutron experiments of
Nakamoto et al. show that the RRR of Cu is reduced from 200 to 50-120 for a
fluence of 10^{21} n/cm^{2}, it follows that the inclusion of all high energy
sources would lead to RRR values well below 50, thus endangering stability and
protection. This result confirms the necessity of including a tungsten shield
inside the quadrupoles.
