Diffraction and rapidity gap measurements in ATLAS

Pseudorapidity gap distributions in Large Hadron Collider proton-proton collisions at sqs\nare studied using a minimum bias data sample of integrated luminosity $7.1 { m mu b^{-1}}$. Cross sections are measured differentially in the size detaf of the larger of the pseudorapidity regions extending to the limits of the ATLAS sensitivity, at $eta = pm 4.9$, in which no final state particles are produced above a transverse momentum threshold ptcut. The measurements span the region $0 < detaf < 8$ for $200 < ptcut < 800$~MeV. The measured data, at large detaf, constrain value of pomeron intercept appropriate to triple Regge models while at small detaf, data test reliability of hadronisation models in describing rapidity and transverse momentum fluctuations in final state particle production.