D.A. Faus(1), M. Haguenauer(2), K. Kasahara(3), K. Masuda(4), Y. Matsubara(4), Y. Muraki(4), T. Sako(4), T. Tamura(5), S. Torii(5), W.C. Turner(6), J. Velasco(1) ( The LHCf collaboration (tentative) )

1. Why LHC ?2. What we can measure 3. Importance of measurement 4. Detector 5. Expected performance6. Bonus7. Conclusions

2004/02/26: ICRR

LHC 2007. 7 TeV x 7 TeV 10⇒ 17 eV 　 Lab.Energy

No knowledge of particle production spectrum at high energies ( esp. at large 　 Feynmann 　 x ). Exception: UA7 exp. at 200TeV

General Structure of LHCBeam collision point Point 140m away

Beam center finding by 40k events

Bonus: LPM effect

1. X distribution of photons at x>0.05.

2. Inelasticity information from neutron spectrum

3. ⇒Calibration of M.C code

4. Bonus. LPM effect.

5. If everything goes well, only ~a day measurement with the smallest detector in the largest accelerator gives us valuable information.