Jet measurement with the CASTOR calorimeter

The measurement of low $p_T$ ($> 3$ GeV) very forward ($\sim 6$) jets with the CASTOR calorimeter of the CMS experiment is presented. The CASTOR (Centauro And STrange Objects Research) calorimeter is covering the pseudorapidity range $-6.6 < \eta < -5.2$ and is located at -14.37 m from the interaction point. This study is based on a very low pile-up sample of proton-proton collisions at a centre-of-mass energy $\sqrt{s} = 7$ TeV, taken by the CMS experiment during the Commissioning 2010 run period.