The pseudorapidity density of charged particles dN(ch)/deta is measured by the TOTEM experiment in pp collisions at sqrt(s) = 8 TeV within the range 3.9 < eta < 4.7 and -6.95 < eta < -6.9. Data were collected in a low intensity LHC run with collision
s occurring at a distance of 11.25 m from the nominal interaction point. The data sample is expected to include 96-97% of the inelastic proton-proton interactions. The measurement reported here considers charged particles with p_T > 0 MeV/c, produced in inelastic interactions with at least one charged particle in -7 < eta < -6 or 3.7 < eta <4.8 . The dN(ch)/deta has been found to decrease with |eta|, from 5.11 +- 0.73 at eta = 3.95 to 1.81 +- 0.56 at eta= - 6.925. Several MC generators are compared to the data and are found to be within the systematic uncertainty of the measurement.
Precise knowledge of the beam optics at the LHC is crucial to fulfil the physics goals of the TOTEM experiment, where the kinematics of the scattered protons is reconstructed with the near-beam telescopes -- so-called Roman Pots (RP). Before being de
tected, the protons trajectories are influenced by the magnetic fields of the accelerator lattice. Thus precise understanding of the proton transport is of key importance for the experiment. A novel method of optics evaluation is proposed which exploits kinematical distributions of elastically scattered protons observed in the RPs. Theoretical predictions, as well as Monte Carlo studies, show that the residual uncertainty of this optics estimation method is smaller than 0.25 percent.
Proton-proton elastic scattering has been measured by the TOTEM experiment at the CERN Large Hadron Collider at {surd}s = 7 TeV in dedicated runs with the Roman Pot detectors placed as close as seven times the transverse beam size (sbeam) from the ou
tgoing beams. After careful study of the accelerator optics and the detector alignment, |t|, the square of four-momentum transferred in the elastic scattering process, has been determined with an uncertainty of d t = 0.1GeV p|t|. In this letter, first results of the differential cross section are presented covering a |t|-range from 0.36 to 2.5GeV2. The differential cross-section in the range 0.36 < |t| < 0.47 GeV2 is described by an exponential with a slope parameter B = (23.6{pm}0.5stat {pm}0.4syst)GeV-2, followed by a significant diffractive minimum at |t| = (0.53{pm}0.01stat{pm}0.01syst)GeV2. For |t|-values larger than ~ 1.5GeV2, the cross-section exhibits a power law behaviour with an exponent of -7.8_pm} 0.3stat{pm}0.1syst. When compared to predictions based on the different available models, the data show a strong discriminative power despite the small t-range covered.
