The CERN Neutrino beam to Gran Sasso (NGS) Addendum to report CERN 98-02, INFN/AE-98/05

The conceptual technical design of the NGS (CERN neutrino beam to Gran Sasso) facility has been presented in the report CERN 98-02 / INFN-AE/98-05. Additional information, in particular an update on various neutrino beam options for the NGS facility, has been provided in a memorandum to the CERN-SPSC Committee (CERN-SPSC/98-35). In the present report, further improvements on the NGS design and performance, in particular new scenarios for SPS proton cycles for NGS operation and a new version of the NGS 'high-energy' neutrino beam for appearance experiments, are described. This new NGS reference beam is estimated to provide three times more events per year than the beam presented in the 1998 report. The radiological aspects of the NGS facility have been re-examined with the new beam design. An updated version of the construction schedule is also presented.