The TOTEM experiment at the CERN LHC has measured elastic proton-proton scattering at the centre-of-mass energy Formula omittedTeV and four-momentum transfers squared, |t|, from Formula omitted to ...0.2 GeV Formula omitted. Near the lower end of the t-interval the differential cross-section is sensitive to the interference between the hadronic and the electromagnetic scattering amplitudes. This article presents the elastic cross-section measurement and the constraints it imposes on the functional forms of the modulus and phase of the hadronic elastic amplitude. The data exclude the traditional Simplified West and Yennie interference formula that requires a constant phase and a purely exponential modulus of the hadronic amplitude. For parametrisations of the hadronic modulus with second- or third-order polynomials in the exponent, the data are compatible with hadronic phase functions giving either central or peripheral behaviour in the impact parameter picture of elastic scattering. In both cases, the Formula omitted-parameter is found to be Formula omitted. The results for the total hadronic cross-section are Formula omitted mb and Formula omitted mb for central and peripheral phase formulations, respectively. Both are consistent with previous TOTEM measurements.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Here, the TOTEM experiment at the CERN LHC has measured elastic proton–proton scattering at the centre-of-mass energy s√=8TeV and four-momentum transfers squared, |t|, from 6 × 10–4 to 0.2 GeV2. Near ...the lower end of the t-interval the differential cross-section is sensitive to the interference between the hadronic and the electromagnetic scattering amplitudes. This article presents the elastic cross-section measurement and the constraints it imposes on the functional forms of the modulus and phase of the hadronic elastic amplitude. The data exclude the traditional Simplified West and Yennie interference formula that requires a constant phase and a purely exponential modulus of the hadronic amplitude. For parametrisations of the hadronic modulus with second- or third-order polynomials in the exponent, the data are compatible with hadronic phase functions giving either central or peripheral behaviour in the impact parameter picture of elastic scattering. In both cases, the ρ-parameter is found to be 0.12±0.03. The results for the total hadronic cross-section are σtot = (102.9±2.3) mb and (103.0±2.3) mb for central and peripheral phase formulations, respectively. Both are consistent with previous TOTEM measurements.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The TOTEM experiment has made a precise measurement of the elastic proton–proton differential cross-section at the centre-of-mass energy s=8 TeV based on a high-statistics data sample obtained with ...the β⁎=90 m optics. Both the statistical and systematic uncertainties remain below 1%, except for the t-independent contribution from the overall normalisation. This unprecedented precision allows to exclude a purely exponential differential cross-section in the range of four-momentum transfer squared 0.027<|t|<0.2 GeV2 with a significance greater than 7 σ. Two extended parametrisations, with quadratic and cubic polynomials in the exponent, are shown to be well compatible with the data. Using them for the differential cross-section extrapolation to t=0, and further applying the optical theorem, yields total cross-section estimates of (101.5±2.1) mb and (101.9±2.1) mb, respectively, in agreement with previous TOTEM measurements.
(ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image).The pseudorapidity density of charged particles dN.../d... is measured by the TOTEM experiment in proton-proton collisions ...at ... TeV within the range ... and ... Data were collected in a low intensity LHC run with collisions 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 ... MeV/c, produced in inelastic interactions with at least one charged particle in ... or ... The dN.../d... has been found to decrease with ..., from 5.11 ... 0.73 at ... to 1.81 ... 0.56 at ...6.925. Several Monte Carlo generators are compared to the data and are found to be within the systematic uncertainty of the measurement.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The pseudorapidity density of charged particles dNch/dη is measured by the TOTEM experiment in proton–proton collisions at √s = 8 TeV within the range 3.9 < η < 4.7 and –6.95 < η < –6.9. Data were ...collected in a low intensity LHC run with collisions 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 pT > 0 MeV/c, produced in inelastic interactions with at least one charged particle in –7 < η < –6 or 3.7 < η < 4.8. The dNch/dη has been found to decrease with |η|, from 5.11 ± 0.73 at η = 3.95 to 1.81 ± 0.56 at η = –6.925. Several Monte Carlo generators are compared to the data and are found to be within the systematic uncertainty of the measurement.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
We describe the design and construction of the first triple-GEM chamber prototypes for the TOTEM detector at CERN LHC. The chambers are semicircular, with an inner and outer radius of the active area ...of about 40 and 150 mm; six to eight detectors will be mounted on each arm. Each chamber has analogue readout of the charge on concentric circular strips, at 400 /spl mu/m pitch, to obtain the radial coordinates, and about 1000 pads of sizes between 3/spl times/3 and 7/spl times/7 mm/sup 2/ with digital readout, used to generate the triggering in combination with the other chambers.
High resolution scanning system was used to locate the areas on GEM-foils that might contain short-circuit. These areas were analyzed by threshold method for fast identification. Different methods to ...remove short-circuits on GEM-foils were studied. Since using the standard procedure of “burning” shorts with high current might incur additional damage to the foil, we have also studied several non-destructive methods. These methods were for example washing with high power ultrasonic, manual extirpation and by using resonance frequencies. We will show results on locating and removing the GEM-shorts from standard bi-conical 10cm ¥ 10cm foils.
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