spnego authentication logs

HEllo experts,we have enabled desktop SSO using spnego on portal(nw7.3 ehp1 sp7),but could not find authentication logs in security audit log if user has succesfully logon or not.

where to check if user has succesfully logon using sso .if we rlogin with password we can find an entry with login ok for the user id but for sso no entry.

Thanks,

Siddharth