Discussion Jan 15, 2015.

1. Cross section
1. 1 barn = 10^(-28) m^2
2. 1 mb = 10 ^(-27) cm^2
3. pp cross section at 7 TeV ~ 100 mb
   Luminosity ~ 10^34 cm^2 / s
   Cross-section ~ 100 mb
   than : about 10^9 events / s
4. Bunch spacing : 50 ns at 7 & 8 TeV and will be 25s at 13 TeV
2. Cross section
1. ttbar -> 250 pb at 8TeV , 800 pb (~10^-33 cm^2) at 14TeV
2. Instant Luminosity : 10 ^ 33 cm^-2 s^-1
3. about 1 ttbar events per 1 sec, about 10pi M events per year.
3. Next time
1. quark and gluon property
2. Neutrino cross section -> 1GeV of it 10^-38cm^2 (nu p)