K. Österberg

TOTEM has measured the differential cross-section for elastic proton-proton scattering at the LHC energy of analysing data from a short run with dedicated large-β* optics. A single exponential fit with a slope B=(20.1±0.2stat±0.3syst) GeV−2 describes the range of the four-momentum transfer squared |t| from 0.02 to 0.33 GeV2. After the extrapolation to |t|=0, a total elastic scattering cross-section of (24.8±0.2stat±1.2syst) mb was obtained. Applying the optical theorem and using the luminosity measurement from CMS, a total proton-proton cross-section of (98.3±0.2stat±2.8syst) mb was deduced which is in good agreement with the expectation from the overall fit of previously measured data over a large range of center-of-mass energies. From the total and elastic pp cross-section measurements, an inelastic pp cross-section of was inferred.

The TOTEM collaboration has measured the proton-proton total cross section at √s=8 TeV using a luminosity-independent method. In LHC fills with dedicated beam optics, the Roman pots have been inserted very close to the beam allowing the detection of ~90% of the nuclear elastic scattering events. Simultaneously the inelastic scattering rate has been measured by the T1 and T2 telescopes. By applying the optical theorem, the total proton-proton cross section of (101.7±2.9) mb has been determined, well in agreement with the extrapolation from lower energies. This method also allows one to derive the luminosity-independent elastic and inelastic cross sections: σ(el)=(27.1±1.4) mb; σ(inel)=(74.7±1.7) mb.

The TOTEM experiment has made a precise measurement of the elastic proton–proton differential cross-section at the centre-of-mass energy s=8TeV based on a high-statistics data sample obtained with the β⁎=90m 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|<0.2GeV2 with a significance greater than 7σ. 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.

The TOTEM Experiment will measure the total pp cross-section with the luminosity-independent method and study elastic and diffractive scattering at the LHC. To achieve optimum forward coverage for charged particles emitted by the pp collisions in the interaction point IP5, two tracking telescopes, T1 and T2, will be installed on each side in the pseudorapidity region 3.1 ⩽ |η| ⩽ 6.5, and Roman Pot stations will be placed at distances of ±147 m and ±220 m from IP5. Being an independent experiment but technically integrated into CMS, TOTEM will first operate in standalone mode to pursue its own physics programme and at a later stage together with CMS for a common physics programme. This article gives a description of the TOTEM apparatus and its performance.

Proton-proton elastic scattering has been measured by the TOTEM experiment at the CERN Large Hadron Collider at in dedicated runs with the Roman Pot detectors placed as close as seven times the transverse beam size (σbeam) from the outgoing 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 . In this letter, first results of the differential cross-section are presented covering a |t|-range from 0.36 to 2.5 GeV2. 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 ± 0.5stat ± 0.4syst) GeV−2, followed by a significant diffractive minimum at |t| = (0.53 ± 0.01stat ± 0.01syst) GeV2. For |t|-values larger than ∼1.5 GeV2, the cross-section exhibits a power law behaviour with an exponent of −7.8 ± 0.3stat ± 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.

The TOTEM experiment at the CERN LHC has measured elastic proton–proton scattering at the centre-of-mass energy $$\sqrt{s}=8\,$$ TeV and four-momentum transfers squared, |t|, from $$6\times 10^{-4}$$ to 0.2 GeV $$^{2}$$ . 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 $$\rho $$ -parameter is found to be $$0.12 \pm 0.03$$ . The results for the total hadronic cross-section are $$\sigma _\mathrm{tot} = (102.9 \pm 2.3)$$ mb and $$(103.0 \pm 2.3)$$ mb for central and peripheral phase formulations, respectively. Both are consistent with previous TOTEM measurements.

The TOTEM collaboration has measured the proton–proton total cross section at $$\sqrt{s}=13~\hbox {TeV}$$ with a luminosity-independent method. Using dedicated $$\beta ^{*}=90~\hbox {m}$$ beam optics, the Roman Pots were inserted very close to the beam. The inelastic scattering rate has been measured by the T1 and T2 telescopes during the same LHC fill. After applying the optical theorem the total proton–proton cross section is $$\sigma _\mathrm{tot}=(110.6~\pm ~3.4$$ ) mb, well in agreement with the extrapolation from lower energies. This method also allows one to derive the luminosity-independent elastic and inelastic cross sections: $$\sigma _\mathrm{el}=(31.0~\pm ~1.7)~\hbox {mb}$$ and $$\sigma _\mathrm{inel}=(79.5~\pm ~1.8)~\hbox {mb}$$ .

Abstract The TOTEM experiment at the LHC has performed the first measurement at $$\sqrt{s} = 13\,\mathrm{TeV}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msqrt><mml:mi>s</mml:mi></mml:msqrt><mml:mo>=</mml:mo><mml:mn>13</mml:mn><mml:mspace /><mml:mi>TeV</mml:mi></mml:mrow></mml:math> of the $$\rho $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>ρ</mml:mi></mml:math> parameter, the real to imaginary ratio of the nuclear elastic scattering amplitude at $$t=0$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>t</mml:mi><mml:mo>=</mml:mo><mml:mn>0</mml:mn></mml:mrow></mml:math> , obtaining the following results: $$\rho = 0.09 \pm 0.01$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>ρ</mml:mi><mml:mo>=</mml:mo><mml:mn>0.09</mml:mn><mml:mo>±</mml:mo><mml:mn>0.01</mml:mn></mml:mrow></mml:math> and $$\rho = 0.10 \pm 0.01$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>ρ</mml:mi><mml:mo>=</mml:mo><mml:mn>0.10</mml:mn><mml:mo>±</mml:mo><mml:mn>0.01</mml:mn></mml:mrow></mml:math> , depending on different physics assumptions and mathematical modelling. The unprecedented precision of the $$\rho $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>ρ</mml:mi></mml:math> measurement, combined with the TOTEM total cross-section measurements in an energy range larger than $$10\,\mathrm{TeV}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>10</mml:mn><mml:mspace /><mml:mi>TeV</mml:mi></mml:mrow></mml:math> (from 2.76 to $$13\,\mathrm{TeV}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>13</mml:mn><mml:mspace /><mml:mi>TeV</mml:mi></mml:mrow></mml:math> ), has implied the exclusion of all the models classified and published by COMPETE. The $$\rho $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>ρ</mml:mi></mml:math> results obtained by TOTEM are compatible with the predictions, from other theoretical models both in the Regge-like framework and in the QCD framework, of a crossing-odd colourless 3-gluon compound state exchange in the t -channel of the proton–proton elastic scattering. On the contrary, if shown that the crossing-odd 3-gluon compound state t -channel exchange is not of importance for the description of elastic scattering, the $$\rho $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>ρ</mml:mi></mml:math> value determined by TOTEM would represent a first evidence of a slowing down of the total cross-section growth at higher energies. The very low-| t | reach allowed also to determine the absolute normalisation using the Coulomb amplitude for the first time at the LHC and obtain a new total proton–proton cross-section measurement $$\sigma _{\mathrm{tot}} = (110.3 \pm 3.5)\,\mathrm{mb}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>σ</mml:mi><mml:mi>tot</mml:mi></mml:msub><mml:mo>=</mml:mo><mml:mrow><mml:mo>(</mml:mo><mml:mn>110.3</mml:mn><mml:mo>±</mml:mo><mml:mn>3.5</mml:mn><mml:mo>)</mml:mo></mml:mrow><mml:mspace /><mml:mi>mb</mml:mi></mml:mrow></mml:math> , completely independent from the previous TOTEM determination. Combining the two TOTEM results yields $$\sigma _{\mathrm{tot}} = (110.5 \pm 2.4)\,\mathrm{mb}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>σ</mml:mi><mml:mi>tot</mml:mi></mml:msub><mml:mo>=</mml:mo><mml:mrow><mml:mo>(</mml:mo><mml:mn>110.5</mml:mn><mml:mo>±</mml:mo><mml:mn>2.4</mml:mn><mml:mo>)</mml:mo></mml:mrow><mml:mspace /><mml:mi>mb</mml:mi></mml:mrow></mml:math> .

The Compact Linear Collider (CLIC) is a multi-TeV high-luminosity linear e+e- collider under development. For an optimal exploitation of its physics potential, CLIC is foreseen to be built and operated in a staged approach with three centre-of-mass energy stages ranging from a few hundred GeV up to 3 TeV. The first stage will focus on precision Standard Model physics, in particular Higgs and top-quark measurements. Subsequent stages will focus on measurements of rare Higgs processes, as well as searches for new physics processes and precision measurements of new states, e.g. states previously discovered at LHC or at CLIC itself. In the 2012 CLIC Conceptual Design Report, a fully optimised 3 TeV collider was presented, while the proposed lower energy stages were not studied to the same level of detail. This report presents an updated baseline staging scenario for CLIC. The scenario is the result of a comprehensive study addressing the performance, cost and power of the CLIC accelerator complex as a function of centre-of-mass energy and it targets optimal physics output based on the current physics landscape. The optimised staging scenario foresees three main centre-of-mass energy stages at 380 GeV, 1.5 TeV and 3 TeV for a full CLIC programme spanning 22 years. For the first stage, an alternative to the CLIC drive beam scheme is presented in which the main linac power is produced using X-band klystrons.

The Compact Linear Collider (CLIC) is a TeV-scale high-luminosity linear $e^+e^-$ collider under development at CERN. Following the CLIC conceptual design published in 2012, this report provides an overview of the CLIC project, its current status, and future developments. It presents the CLIC physics potential and reports on design, technology, and implementation aspects of the accelerator and the detector. CLIC is foreseen to be built and operated in stages, at centre-of-mass energies of 380 GeV, 1.5 TeV and 3 TeV, respectively. CLIC uses a two-beam acceleration scheme, in which 12 GHz accelerating structures are powered via a high-current drive beam. For the first stage, an alternative with X-band klystron powering is also considered. CLIC accelerator optimisation, technical developments and system tests have resulted in an increased energy efficiency (power around 170 MW) for the 380 GeV stage, together with a reduced cost estimate at the level of 6 billion CHF. The detector concept has been refined using improved software tools. Significant progress has been made on detector technology developments for the tracking and calorimetry systems. A wide range of CLIC physics studies has been conducted, both through full detector simulations and parametric studies, together providing a broad overview of the CLIC physics potential. Each of the three energy stages adds cornerstones of the full CLIC physics programme, such as Higgs width and couplings, top-quark properties, Higgs self-coupling, direct searches, and many precision electroweak measurements. The interpretation of the combined results gives crucial and accurate insight into new physics, largely complementary to LHC and HL-LHC. The construction of the first CLIC energy stage could start by 2026. First beams would be available by 2035, marking the beginning of a broad CLIC physics programme spanning 25-30 years.

Abstract The TOTEM collaboration has measured the elastic proton-proton differential cross section $$\mathrm{d}\sigma /\mathrm{d}t$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>d</mml:mi><mml:mi>σ</mml:mi><mml:mo>/</mml:mo><mml:mi>d</mml:mi><mml:mi>t</mml:mi></mml:mrow></mml:math> at $$\sqrt{s}=13$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msqrt><mml:mi>s</mml:mi></mml:msqrt><mml:mo>=</mml:mo><mml:mn>13</mml:mn></mml:mrow></mml:math> TeV LHC energy using dedicated $$\beta ^{*}=90$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msup><mml:mi>β</mml:mi><mml:mrow><mml:mrow /><mml:mo>∗</mml:mo></mml:mrow></mml:msup><mml:mo>=</mml:mo><mml:mn>90</mml:mn></mml:mrow></mml:math> m beam optics. The Roman Pot detectors were inserted to 10 $$\sigma $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>σ</mml:mi></mml:math> distance from the LHC beam, which allowed the measurement of the range [0.04 GeV $$^{2}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msup><mml:mrow /><mml:mn>2</mml:mn></mml:msup></mml:math> ; 4 GeV $$^{2}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msup><mml:mrow /><mml:mn>2</mml:mn></mml:msup></mml:math> $$]$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mo>]</mml:mo></mml:math> in four-momentum transfer squared | t |. The efficient data acquisition allowed to collect about 10 $$^{9}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msup><mml:mrow /><mml:mn>9</mml:mn></mml:msup></mml:math> elastic events to precisely measure the differential cross-section including the diffractive minimum (dip), the subsequent maximum (bump) and the large-| t | tail. The average nuclear slope has been found to be $$B=(20.40 \pm 0.002^{\mathrm{stat}} \pm 0.01^{\mathrm{syst}})~$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>B</mml:mi><mml:mo>=</mml:mo><mml:mo>(</mml:mo><mml:mn>20.40</mml:mn><mml:mo>±</mml:mo><mml:mn>0</mml:mn><mml:mo>.</mml:mo><mml:msup><mml:mn>002</mml:mn><mml:mi>stat</mml:mi></mml:msup><mml:mo>±</mml:mo><mml:mn>0</mml:mn><mml:mo>.</mml:mo><mml:msup><mml:mn>01</mml:mn><mml:mi>syst</mml:mi></mml:msup><mml:mo>)</mml:mo><mml:mspace /></mml:mrow></mml:math> GeV $$^{-2}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msup><mml:mrow /><mml:mrow><mml:mo>-</mml:mo><mml:mn>2</mml:mn></mml:mrow></mml:msup></mml:math> in the | t |-range 0.04–0.2 GeV $$^{2}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msup><mml:mrow /><mml:mn>2</mml:mn></mml:msup></mml:math> . The dip position is $$|t_{\mathrm{dip}}|=(0.47 \pm 0.004^{\mathrm{stat}} \pm 0.01^{\mathrm{syst}})~$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mrow><mml:mo>|</mml:mo></mml:mrow><mml:msub><mml:mi>t</mml:mi><mml:mi>dip</mml:mi></mml:msub><mml:mrow><mml:mo>|</mml:mo><mml:mo>=</mml:mo></mml:mrow><mml:mrow><mml:mo>(</mml:mo><mml:mn>0.47</mml:mn><mml:mo>±</mml:mo><mml:mn>0</mml:mn><mml:mo>.</mml:mo><mml:msup><mml:mn>004</mml:mn><mml:mi>stat</mml:mi></mml:msup><mml:mo>±</mml:mo><mml:mn>0</mml:mn><mml:mo>.</mml:mo><mml:msup><mml:mn>01</mml:mn><mml:mi>syst</mml:mi></mml:msup><mml:mo>)</mml:mo></mml:mrow><mml:mspace /></mml:mrow></mml:math> GeV $$^{2}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msup><mml:mrow /><mml:mn>2</mml:mn></mml:msup></mml:math> . The differential cross section ratio at the bump vs. at the dip $$R=1.77\pm 0.01^{\mathrm{stat}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>R</mml:mi><mml:mo>=</mml:mo><mml:mn>1.77</mml:mn><mml:mo>±</mml:mo><mml:mn>0</mml:mn><mml:mo>.</mml:mo><mml:msup><mml:mn>01</mml:mn><mml:mi>stat</mml:mi></mml:msup></mml:mrow></mml:math> has been measured with high precision. The series of TOTEM elastic pp measurements show that the dip is a permanent feature of the pp differential cross-section at the TeV scale.

Abstract The proton–proton elastic differential cross section $${\mathrm{d}}\sigma /{\mathrm{d}}t$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>d</mml:mi><mml:mi>σ</mml:mi><mml:mo>/</mml:mo><mml:mi>d</mml:mi><mml:mi>t</mml:mi></mml:mrow></mml:math> has been measured by the TOTEM experiment at $$\sqrt{s}=2.76\hbox { TeV}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msqrt><mml:mi>s</mml:mi></mml:msqrt><mml:mo>=</mml:mo><mml:mn>2.76</mml:mn><mml:mspace /><mml:mtext>TeV</mml:mtext></mml:mrow></mml:math> energy with $$\beta ^{*}=11\hbox { m}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msup><mml:mi>β</mml:mi><mml:mrow><mml:mrow /><mml:mo>∗</mml:mo></mml:mrow></mml:msup><mml:mo>=</mml:mo><mml:mn>11</mml:mn><mml:mspace /><mml:mtext>m</mml:mtext></mml:mrow></mml:math> beam optics. The Roman Pots were inserted to 13 times the transverse beam size from the beam, which allowed to measure the differential cross-section of elastic scattering in a range of the squared four-momentum transfer (| t |) from 0.36 to $$0.74\hbox { GeV}^{2}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>0.74</mml:mn><mml:mspace /><mml:msup><mml:mtext>GeV</mml:mtext><mml:mn>2</mml:mn></mml:msup></mml:mrow></mml:math> . The differential cross-section can be described with an exponential in the | t |-range between 0.36 and $$0.54\hbox { GeV}^{2}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>0.54</mml:mn><mml:mspace /><mml:msup><mml:mtext>GeV</mml:mtext><mml:mn>2</mml:mn></mml:msup></mml:mrow></mml:math> , followed by a diffractive minimum (dip) at $$|t_{\mathrm{dip}}|=(0.61\pm 0.03)\hbox { GeV}^{2}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mrow><mml:mo>|</mml:mo></mml:mrow><mml:msub><mml:mi>t</mml:mi><mml:mi>dip</mml:mi></mml:msub><mml:mrow><mml:mo>|</mml:mo><mml:mo>=</mml:mo><mml:mrow><mml:mo>(</mml:mo><mml:mn>0.61</mml:mn><mml:mo>±</mml:mo><mml:mn>0.03</mml:mn><mml:mo>)</mml:mo></mml:mrow><mml:mspace /></mml:mrow><mml:msup><mml:mtext>GeV</mml:mtext><mml:mn>2</mml:mn></mml:msup></mml:mrow></mml:math> and a subsequent maximum (bump). The ratio of the $${\mathrm{d}}\sigma /{\mathrm{d}}t$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>d</mml:mi><mml:mi>σ</mml:mi><mml:mo>/</mml:mo><mml:mi>d</mml:mi><mml:mi>t</mml:mi></mml:mrow></mml:math> at the bump and at the dip is $$1.7\pm 0.2$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>1.7</mml:mn><mml:mo>±</mml:mo><mml:mn>0.2</mml:mn></mml:mrow></mml:math> . When compared to the proton–antiproton measurement of the D0 experiment at $$\sqrt{s} = 1.96\hbox { TeV}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msqrt><mml:mi>s</mml:mi></mml:msqrt><mml:mo>=</mml:mo><mml:mn>1.96</mml:mn><mml:mspace /><mml:mtext>TeV</mml:mtext></mml:mrow></mml:math> , a significant difference can be observed. Under the condition that the effects due to the energy difference between TOTEM and D0 can be neglected, the result provides evidence for the exchange of a colourless C-odd three-gluon compound state in the t -channel of the proton–proton and proton–antiproton elastic scattering.

The DELPHI Microvertex detector, which has been in operation since the start of the 1990 LEP run, consists of three layers of silicon microstrip detectors at average radii of 6.3, 9.0 and 11.0 cm. The 73728 readout strips, oriented along the beam, have a total active area of 0.42 m2. The strip pitch is 25 μm and every other strip is read out by low power charge amplifiers, giving a signal to noise ratio of 15:1 for minimum ionizing particles. On-line zero suppression results in an average data size of 4 kbyte for Z0 events. After a mechanical survey and an alignment with tracks, the impact parameter uncertainty as determined from hadronic Z0 decays is well described by (69pt)2 + 242 μm, with pt in GeV/c. For the 45 GeV/c tracks from Z0 → μ− decays we find an uncertainty of 21 μm for the impact parameter, which corresponds to a precision of 8 μm per point. The stability during the run is monitored using light spots and capacitive probes. An analysis of tracks through sector overlaps provides an additional check of the stability. The same analysis also results in a value of 6 μm for the intrinsic precision of the detector.

The silicon strip microvertex detector of the DELPHI experiment at the CERN LEP collider has been recently upgraded from two coordinates (RΦ only) to three coordinates reconstruction (RΦ and z). The new Microvertex detector consists of 125 952 readout channels, and uses novel techniques to obtain the third coordinate. These include the use of AC coupled double sided silicon detectors with strips orthogonal to each other on opposite sides of the detector wafer. The routing of signals from the z strips to the end of the detector modules is done with a second metal layer on the detector surface, thus keeping the material in the sensitive area to a minimum. Pairs of wafers are daisy chained, with the wafers within each pair flipped with respect to each other in order to minimize the load capacitance on the readout amplifiers. The design of the detector and its various components are described. Results on the performance of the new detector are presented, with special emphasis on alignment, intrinsic precision and impact parameter resolution. The new detector has been taking data since spring of 1994, performing up to design specifications.

The first double diffractive cross-section measurement in the very forward region has been carried out by the TOTEM experiment at the LHC with center-of-mass energy of sqrt(s)=7 TeV. By utilizing the very forward TOTEM tracking detectors T1 and T2, which extend up to |eta|=6.5, a clean sample of double diffractive pp events was extracted. From these events, we measured the cross-section sigma_DD =(116 +- 25) mub for events where both diffractive systems have 4.7 <|eta|_min < 6.5 .

The TOTEM experiment has measured the charged-particle pseudorapidity density dNch/dη in pp collisions at for 5.3<|η|<6.4 in events with at least one charged particle with transverse momentum above 40 MeV/c in this pseudorapidity range. This extends the analogous measurement performed by the other LHC experiments to the previously unexplored forward η region. The measurement refers to more than 99% of non-diffractive processes and to single and double diffractive processes with diffractive masses above ∼3.4 GeV/c2, corresponding to about 95% of the total inelastic cross-section. The dNch/dη has been found to decrease with |η|, from 3.84 ± 0.01(stat) ± 0.37(syst) at |η|=5.375 to 2.38±0.01(stat)±0.21(syst) at |η|=6.375. Several MC generators have been compared to data; none of them has been found to fully describe the measurement.

The DELPHI Silicon Tracker, an ensemble of microstrips, ministrips and pixels, was completed in 1997 and has accumulated over 70pb−1 of high-energy data. The Tracker is optimised for the LEP2 physics programme. It consists of a silicon microstrip barrel and endcaps with layers of silicon pixel and ministrip detectors. In the barrel part, three-dimensional b tagging information is available down to a polar angle of 25°. Impact parameter resolutions have been measured of 28μm ⊕71/(psin3/2θ)μm in Rφ and 34μm ⊕69/pμm in Rz, where p is the track momentum in GeV/c. The amount of material has been kept low with the use of double-sided detectors, double-metal readout, and light mechanics. The pixels have dimensions of 330×330μm2 and the ministrips have a readout pitch of 200μm. The forward part of the detector shows average efficiencies of more than 96%, has signal-to-noise ratios of up to 40 in the ministrips, and noise levels at the level of less than one part per million in the pixels. Measurements of space points with low backgrounds are provided, leading to a vastly improved tracking efficiency for the region with polar angle less than 25°.

Proton-proton elastic scattering has been measured by the TOTEM experiment at the CERN Large Hadron Collider at √s = 7 TeV in special runs with the Roman Pot detectors placed as close to the outgoing beam as seven times the transverse beam size. The differential cross-section measurements are reported in the |t|-range of 0.36 to 2.5 GeV2. Extending the range of data to low t values from 0.02 to 0.33 GeV2, and utilizing the luminosity measurements of CMS, the total proton-proton cross section at √s = 7 TeV is measured to be (98.3 ±0.2stat ±2.8syst) mb.

The TOTEM Experiment is designed to measure the total proton-proton cross-section with the luminosity-independent method and to study elastic and diffractive pp scattering at the LHC. To achieve optimum forward coverage for charged particles emitted by the pp collisions in the interaction point IP5, two tracking telescopes, T1 and T2, are installed on each side of the IP in the pseudorapidity region 3.1 < = |eta | < = 6.5, and special movable beam-pipe insertions - called Roman Pots (RP) - are placed at distances of +- 147 m and +- 220 m from IP5. This article describes in detail the working of the TOTEM detector to produce physics results in the first three years of operation and data taking at the LHC.

This paper describes the design and the performance of the timing detector developed by the TOTEM Collaboration for the Roman Pots (RPs) to measure the Time-Of-Flight (TOF) of the protons produced in central diffractive interactions at the LHC . The measurement of the TOF of the protons allows the determination of the longitudinal position of the proton interaction vertex and its association with one of the vertices reconstructed by the CMS detectors. The TOF detector is based on single crystal Chemical Vapor Deposition (scCVD) diamond plates and is designed to measure the protons TOF with about 50 ps time precision. This upgrade to the TOTEM apparatus will be used in the LHC run 2 and will tag the central diffractive events up to an interaction pileup of about 1. A dedicated fast and low noise electronics for the signal amplification has been developed. The digitization of the diamond signal is performed by sampling the waveform. After introducing the physics studies that will most profit from the addition of these new detectors, we discuss in detail the optimization and the performance of the first TOF detector installed in the LHC in November 2015.

Silicon detectors for the Roman Pots of the large hadron collider TOTEM experiment aim for full sensitivity at the edge where a terminating structure is required for electrical stability. This work provides an innovative approach reducing the conventional width of the terminating structure to less than 100 microns, still using standard planar fabrication technology. The objective of this new development is to decouple the electric behaviour of the surface from the sensitive volume within tens of microns. The explanation of the basic principle of this new approach together with the experimental confirmation via electric measurements and beam test are presented in this paper, demonstrating that silicon detectors with this new terminating structure are fully operational and efficient to under 60 microns from the die cut.

The pseudorapidity density of charged particles dN $$_{ ch }$$ /d $$\eta $$ is measured by the TOTEM experiment in proton–proton 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 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 $$p_T>0$$ MeV/c, produced in inelastic interactions with at least one charged particle in $$-7<\eta <-6$$ or $$3.7<\eta <4.8$$ . The dN $$_{ ch }$$ /d $$\eta $$ has been found to decrease with $$|\eta |$$ , from 5.11 $$\pm $$ 0.73 at $$\eta =3.95$$ to 1.81 $$\pm $$ 0.56 at $$\eta =-$$ 6.925. Several Monte Carlo 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 detected, 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.

Abstract The TOTEM collaboration at the CERN LHC has measured the differential cross-section of elastic proton–proton scattering at $$\sqrt{s} = 8\,\mathrm{TeV}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msqrt> <mml:mi>s</mml:mi> </mml:msqrt> <mml:mo>=</mml:mo> <mml:mn>8</mml:mn> <mml:mspace /> <mml:mi>TeV</mml:mi> </mml:mrow> </mml:math> in the squared four-momentum transfer range $$0.2\,\mathrm{GeV^{2}}&lt; |t| &lt; 1.9\,\mathrm{GeV^{2}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mn>0.2</mml:mn> <mml:mspace /> <mml:msup> <mml:mi>GeV</mml:mi> <mml:mn>2</mml:mn> </mml:msup> <mml:mo>&lt;</mml:mo> <mml:mrow> <mml:mo>|</mml:mo> <mml:mi>t</mml:mi> <mml:mo>|</mml:mo> </mml:mrow> <mml:mo>&lt;</mml:mo> <mml:mn>1.9</mml:mn> <mml:mspace /> <mml:msup> <mml:mi>GeV</mml:mi> <mml:mn>2</mml:mn> </mml:msup> </mml:mrow> </mml:math> . This interval includes the structure with a diffractive minimum (“dip”) and a secondary maximum (“bump”) that has also been observed at all other LHC energies, where measurements were made. A detailed characterisation of this structure for $$\sqrt{s} = 8\,\mathrm{TeV}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msqrt> <mml:mi>s</mml:mi> </mml:msqrt> <mml:mo>=</mml:mo> <mml:mn>8</mml:mn> <mml:mspace /> <mml:mi>TeV</mml:mi> </mml:mrow> </mml:math> yields the positions, $$|t|_{\mathrm{dip}} = (0.521 \pm 0.007)\,\mathrm{GeV^2}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub> <mml:mrow> <mml:mo>|</mml:mo> <mml:mi>t</mml:mi> <mml:mo>|</mml:mo> </mml:mrow> <mml:mi>dip</mml:mi> </mml:msub> <mml:mo>=</mml:mo> <mml:mrow> <mml:mo>(</mml:mo> <mml:mn>0.521</mml:mn> <mml:mo>±</mml:mo> <mml:mn>0.007</mml:mn> <mml:mo>)</mml:mo> </mml:mrow> <mml:mspace /> <mml:msup> <mml:mi>GeV</mml:mi> <mml:mn>2</mml:mn> </mml:msup> </mml:mrow> </mml:math> and $$|t|_{\mathrm{bump}} = (0.695 \pm 0.026)\,\mathrm{GeV^2}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub> <mml:mrow> <mml:mo>|</mml:mo> <mml:mi>t</mml:mi> <mml:mo>|</mml:mo> </mml:mrow> <mml:mi>bump</mml:mi> </mml:msub> <mml:mo>=</mml:mo> <mml:mrow> <mml:mo>(</mml:mo> <mml:mn>0.695</mml:mn> <mml:mo>±</mml:mo> <mml:mn>0.026</mml:mn> <mml:mo>)</mml:mo> </mml:mrow> <mml:mspace /> <mml:msup> <mml:mi>GeV</mml:mi> <mml:mn>2</mml:mn> </mml:msup> </mml:mrow> </mml:math> , as well as the cross-section values, $$\left. {\mathrm{d}\sigma /\mathrm{d}t}\right| _{\mathrm{dip}} = (15.1 \pm 2.5)\,\mathrm{{\mu b/GeV^2}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub> <mml:mfenced> <mml:mrow> <mml:mi>d</mml:mi> <mml:mi>σ</mml:mi> <mml:mo>/</mml:mo> <mml:mi>d</mml:mi> <mml:mi>t</mml:mi> </mml:mrow> </mml:mfenced> <mml:mi>dip</mml:mi> </mml:msub> <mml:mo>=</mml:mo> <mml:mrow> <mml:mo>(</mml:mo> <mml:mn>15.1</mml:mn> <mml:mo>±</mml:mo> <mml:mn>2.5</mml:mn> <mml:mo>)</mml:mo> </mml:mrow> <mml:mspace /> <mml:mrow> <mml:mi>μ</mml:mi> <mml:mi>b</mml:mi> <mml:mo>/</mml:mo> <mml:msup> <mml:mi>GeV</mml:mi> <mml:mn>2</mml:mn> </mml:msup> </mml:mrow> </mml:mrow> </mml:math> and $$\left. {\mathrm{d}\sigma /\mathrm{d}t}\right| _{\mathrm{bump}} = (29.7 \pm 1.8)\,\mathrm{{\mu b/GeV^2}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub> <mml:mfenced> <mml:mrow> <mml:mi>d</mml:mi> <mml:mi>σ</mml:mi> <mml:mo>/</mml:mo> <mml:mi>d</mml:mi> <mml:mi>t</mml:mi> </mml:mrow> </mml:mfenced> <mml:mi>bump</mml:mi> </mml:msub> <mml:mo>=</mml:mo> <mml:mrow> <mml:mo>(</mml:mo> <mml:mn>29.7</mml:mn> <mml:mo>±</mml:mo> <mml:mn>1.8</mml:mn> <mml:mo>)</mml:mo> </mml:mrow> <mml:mspace /> <mml:mrow> <mml:mi>μ</mml:mi> <mml:mi>b</mml:mi> <mml:mo>/</mml:mo> <mml:msup> <mml:mi>GeV</mml:mi> <mml:mn>2</mml:mn> </mml:msup> </mml:mrow> </mml:mrow> </mml:math> , for the dip and the bump, respectively.

Abstract The TOTEM experiment, small in size compared to the others at the LHC, is dedicated to the measurement of the total proton–proton cross-sections with a luminosity-independent method and to the study of elastic and diffractive scattering at the LHC. To achieve optimum forward coverage for charged particles emitted by the pp collisions in the IP5 interaction point, two tracking telescopes, T1 and T2, will be installed on each side in the pseudo-rapidity region between 3.1 and 6.5, and Roman Pot stations will be placed at distances of 147 and 220 m from IP5. The telescope closest to the interaction point (T1, centred at z=9 m) consists of Cathode Strip Chambers (CSC), while the second one (T2, centred at 13.5 m), makes use of Gas Electron Multipliers (GEM). The proton detectors in the Roman Pots are silicon devices designed by TOTEM with the specific objective of reducing down to a few tens of microns the insensitive area at the edge. High efficiency as close as possible to the physical detector boundary is an essential feature. It maximizes the experimental acceptance for protons scattered elastically or interactively at polar angles down to a few micro-radians at IP5. To measure protons at the lowest possible emission angles, special beam optics have been conceived to optimize proton detection in terms of acceptance and resolution. The read-out of all TOTEM subsystems is based on the custom-developed digital VFAT chip with trigger capability.

The TOTEM experiment will detect leading protons scattered in angles of microradians from the interaction point at the large hadron collider. This will be achieved using detectors with a minimized dead area at the edge. The collaboration has developed an innovative structure at the detector edge reducing the conventional dead width to less than 100 μm, still using standard planar fabrication technology. In this new development, the current of the surface is decoupled from the sensitive volume current within a few tens of micrometers. The basic working principle is explained in this paper. Final size detectors have been produced using this approach. The current–voltage and current–temperature characteristics of the detectors were studied and the detectors were successfully tested in a coasting beam experiment.

3D detectors with electrodes penetrating through the silicon wafer and covering the edges were tested in the SPS beam line X5 at CERN in autumn 2003. Detector parameters including efficiency, signal-to-noise ratio, and edge sensitivity were measured using a silicon telescope as a reference system. The measured sensitive width and the known silicon width were equal within less than 10 mum.

At CERNs Large Hadron Collider, a unique possibility to study central exclusive processes such as the production of low mass resonances, charmonium states and jets, as well as to search for missing mass or momentum signatures opens up by the detection of both leading protons with the special β* = 90 m optics. At [Formula: see text] with that optics the leading proton acceptance of the TOTEM Roman Pots covers all diffractive masses, provided that the proton four-momentum transfer |t| ≳ 0.04 GeV 2 . This paper describes the physics potential with an integrated luminosity of 10 pb -1 and 100 pb -1 for common CMS and TOTEM data taking at β* = 90 m optics.

The design and first results from double-sided silicon microstrip detectors designed for use in the DELPHI experiment at LEP are presented. The detectors are AC-coupled on both the n- and p-side. A novel readout scheme using a second metal layer has been implemented, allowing the readout of both coordinates on the same edge of the detector. The detectors have been tested in a high energy beam at the CERN SPS. Results on spatial resolution, pulse-height correlation and charge division are presented. The spatial resolution of the n-side has been measured as a function of the beam particle incident angle from 0 to 60°.

Single crystal CVD (scCVD) diamond is an attractive material for particle detection in high energy physics for its good time resolution and reported outstanding radiation tolerance. In addition to direct signal loss via charge carrier trapping, polarization effect, caused by non-homogeneous filling of trap defects, is a known cause of signal degradation in irradiated scCVD diamond. This phenomenon was studied by intentionally polarizing irradiated diamonds. Even the relatively lightly irradiated (1014 protons/cm2) diamonds exhibited strong enough polarization to collapse the electric field with moderate rate of 5 MeV alpha particles. The transient current measurements were reproduced with TCAD simulations. The hypothesis that the polarization is caused by single neutral defect type in the bulk, was tested using two generic models. Neither one has a satisfactory agreement with the measurement data, which indicates that trapping at the interfaces play a significant role in space charge polarization.

We report on a CDF measurement of the total cross section and rapidity distribution, d{sigma}/dy, for q{bar q} {yields} {gamma}{sup *}/Z {yields} e{sup +} e {sup -} events in the Z boson mass region (66 < M {sub ee} < 116 GeV/c {sub 2}) produced in p{bar p} collisions at {radical}s = 1.96 TeV with 2.1 fb{sup -1} of integrated luminosity. The measured cross section of 257 {+-} 16pb and d{sigma}/dy distribution are compared with Next-to-Leading-Order (NLO) and Next-to-Next-to-Leading-Order (NNLO) QCD theory predictions with CTEQ and MRST/MSTW parton distribution functions (PDFs). There is good agreement between the experimental total cross section and d{sigma}/dy measurements with theoretical calcualtion with the most recent NNLO PDFs.

Abstract A new silicon microstrip detector was designed by the CDF collaboration for the proposed high-luminosity operation of the Tevatron p p ¯ collider (Run IIb). The detector is radiation-tolerant and will still be functional after exposure to particle fluences of 10 14 1 - MeV equivalent neutrons / cm 2 and radiation doses of 20 MRad. The detector will maintain or exceed the performance of the current CDF silicon detector throughout Run IIb. It is based on an innovative silicon “supermodule” design. Critical detector components like the custom radiation-hard SVX4 readout chip, the beryllia hybrids and mini-port (repeater) cards, and the silicon sensors fulfill their specifications and were produced with high yields. The design goals and solutions of the CDF Run IIb silicon detector are described, and the performance of preproduction modules is presented in detail. Results relevant for the development of future silicon systems are emphasized.

The TOTEM collaboration has measured the proton-proton total cross section at $\sqrt{s}=13$ TeV with a luminosity-independent method. Using dedicated $β^{*}=90$ m beam optics, the Roman Pots were inserted very close to the beam. The inelastic scattering rate has been measured by the T1 and T2 telescopes during the same LHC fill. After applying the optical theorem the total proton-proton cross section is $σ_{\rm tot}=(110.6 \pm 3.4$) mb, well in agreement with the extrapolation from lower energies. This method also allows one to derive the luminosity-independent elastic and inelastic cross sections: $σ_{\rm el} = (31.0 \pm 1.7)$ mb and $σ_{\rm inel} = (79.5 \pm 1.8)$ mb.

The CMS and TOTEM experiments intend to carry out a joint diffractive/forward physics program with an unprecedented rapidity coverage. The present document outlines some aspects of such a physics program, which spans from the investigation of the low-x structure of the proton to the diffractive production of a SM or MSSM Higgs boson.

The physics programme of the TOTEM experiment requires the detection of very forward protons scattered by only a few microradians out of the LHC beams. For this purpose, stacks of planar Silicon detectors have been mounted in moveable near-beam telescopes (Roman Pots) located along the beamline on both sides of the interaction point. In order to maximise the proton acceptance close to the beams, the dead space at the detector edge had to be minimised. During the detector prototyping phase, different sensor technologies and designs have been explored. A reduction of the dead space to less than 50 μm has been accomplished with two novel silicon detector technologies: one with the Current Terminating Structure (CTS) design and one based on the 3D edge manufacturing. This paper describes performance studies on prototypes of these detectors, carried out in 2004 in a fixed-target muon beam at CERN's SPS accelerator. In particular, the efficiency and accuracy in the vicinity of the beam-facing edges are discussed.

The total punchthrough probability of showers produced by negatively charged pions of momenta 30, 40, 50, 75, 100, 200 and 300 GeV/c, has been measured in the RD5 experiment at CERN using a toroidal spectrometer. The range of the measurement extends to 5.3 m of equivalent iron. Our results have been obtained by two different analysis methods and are compared with the resutls of a previous experiment.

To fulfil the mechanical requirements set by the luminosity goals of the CLIC collider, currently under study, the 2-m two-beam modules, the shortest repetitive elements in the main linac, have to be controlled at micrometer level. At the same time these modules are exposed to variable high power dissipation while the accelerator is ramped up to nominal power as well as when the mode of CLIC operation is varied. This will result into inevitable temperature excursions driving mechanical distortions in and between different module components. A FEM model is essential to estimate and simulate the fundamental thermo-mechanical behaviour of the CLIC two-beam module to facilitate its design and development. In this paper, the fundamental thermal environments for the RF-components of the module are described. Also the thermal and structural results for the studied module configuration are presented showing the fundamental thermo-mechanical behaviour under the main CLIC collider operation conditions.

We calibrated and determined the measurement uncertainty of a custom-made Fourier domain short coherence interferometer operated in laboratory conditions. We compared the optical thickness of two thickness standards and three coverslips determined with our interferometer to the geometric thickness determined by SEM. Using this calibration data, we derived a calibration function with a 95% confidence level system uncertainty of (5.9×10(-3)r+2.3) μm, where r is the optical distance in μm, across the 240 μm optical measurement range. The confidence limit includes contributions from uncertainties in the optical thickness, geometric thickness, and refractive index measurements as well as uncertainties arising from cosine errors and thermal expansion. The results show feasibility for noncontacting absolute distance characterization with micrometer-level accuracy. This instrument is intended for verifying the alignment of the discs of an accelerating structure in the possible future compact linear collider.

The internal shape and alignment of accelerator discs is crucial for efficient collider operation at the future compact linear collider (CLIC). We applied a calibrated custom-made Fourier-domain short coherence interferometer to measure the height of 40 and 60 μm ultraprecisely turned steps (surface roughness Ra≤25 nm, flatness ≤2 μm) on an oxygen-free electronic copper disc. The step heights were quantified to be (39.6±2.6) μm and (59.0±2.3) μm. The uncertainties are quoted at 95% confidence level and include contributions from calibration, refractive index of air, cosine error, surface roughness, and thermal expansion in comparison to standard temperature of 20°C. The results were verified by measuring the same steps using a commercial white light interferometer Veeco—NT3300. Our instrument can ensure that the accelerator discs of the CLIC are aligned within the tolerance required for efficient collider operation.

The papers review the main theoretical and experimental aspects of the Forward Physics at the Large Hadron Collider.

In order to fully exploit the physics potential of a future high energy e+e- linear collider, a Vertex Tracker, providing high resolution track reconstruction, is required. Hybrid Silicon pixel sensors are an attractive option, for the sensor technology, due to their read-out speed and radiation hardness, favoured in the high rate environment of the TESLA e+e- linear collider design but have been so far limited by the achievable single point space resolution. In this paper, a conceptual design of the TESLA Vertex Tracker, based on a novel layout of hybrid pixel sensors with interleaved cells to improve their spatial resolution, is presented.

The TOTEM experiment is dedicated to the measurement of the total proton–proton cross-section with the luminosity-independent method and the study of elastic and diffractive scattering processes. Two tracking telescopes, T1 and T2, integrated in the CMS detector, cover the pseudo-rapidity region between 3.1 and 6.5 on both sides of the interaction point IP5. The Roman Pot (RP) stations are located at distances of ±147 m and ±220 m with respect to the interaction point to measure the very forward scattered protons at very small angles. During the LHC technical stop in winter 2010/2011, the TOTEM experiment was completed with the installation of the T1 telescope and the RP stations at ±147 m. In 2011, the LHC machine provided special optics with the large ß⁎=90 m, allowing TOTEM to measure the elastic scattering differential cross-section, down to the four-momentum transfer squared |t|=2×10−2 GeV2. Using the optical theorem and extrapolation of the differential cross-section to t=0 (optical point), the total p–p cross-section at the LHC energy of s=7TeV could be computed for the first time. Furthermore we measured with standard LHC beam optics and the energy of s=7TeV the forward charged particle pseudorapidity density dn/dη in the range of 5.3<|η|<6.4. The status of the experiment, the performance of the detectors with emphasis on the RPs are described and the first physics results are presented.

The innermost layer (L00) of the Run IIa silicon detector of CDF was planned to be replaced for the high luminosity Tevatron upgrade of Run IIb. This new silicon layer (L0) is designed to be a radiation tolerant replacement for the otherwise very similar L00 from Run IIa. The data are read out via long, fine-pitch, low-mass cables allowing the hybrids with the chips to sit at higher z(/spl sim/70 cm), outside of the tracking volume. The design and first results from the prototyping phase are presented. Special focus is placed on the amount and the structure of induced noise as well as signal-to-noise values.

We describe the characteristics of silicon microstrip sensors fabricated by Hamamatsu Photonics for the CDF Run 2b silicon detector. A total of 953 sensors, including 117 prototype sensors, have been produced and tested. Five sensors were irradiated with neutrons up to 1.4 /spl times/10/sup 14/ n/cm/sup 2/ as a part of the sensor quality assurance program. The electrical and mechanical characteristics are found to be superior in all aspects and fulfill our specifications. We comment on charge-up susceptibility of the sensors that employ a <100> crystal structure.

The various generations of Silicon Vertex Detectors (SVX, SVX', SVXII) for Collider Detector at Fermilab (CDF) at the Fermilab Tevatron have been fundamental tools for heavy-flavor tagging via secondary vertex detection. The CDF Run IIb Silicon Vertex Detector (SVXIIb) has been designed to be a radiation-tolerant replacement for the currently installed SVXII because SVXII was not expected to survive the Tevatron luminosity anticipated for Run IIb. One major change in the new design is the use of a single mechanical and electrical element throughout the array. This element, called a stave, carries six single-sided silicon sensors on each side and is built using carbon fiber skins with a high thermal conductivity on a foam core with a built-in cooling channel. A Kapton bus cable carries power, data and control signals underneath the silicon sensors on each side of the stave. Sensors are read out in pairs via a ceramic hybrid glued on one of the sensors and equipped with four SVX4 readout chips. This new design concept leads to a very compact mechanical and electrical unit, allowing streamlined production and ease of testing and installation. A description of the design and mechanical performance of the stave is given. Results on the electrical performance obtained using prototype staves are also presented.

The main building block and readout unit of the planned CDF Run IIb silicon detector is a "stave," a highly integrated mechanical, thermal, and electrical structure. One of its characteristic features is a copper-on-Kapton flexible cable for power, high voltage, data transmission, and control signals that is placed directly below the silicon microstrip sensors. The dense packaging makes deadtime-less operation of the stave a challenge since coupling of bus cable activity into the silicon sensors must be suppressed efficiently. The stave design features relevant for deadtime-less operation are discussed. The electrical performance achieved with stave prototypes is presented.

The TOTEM collaboration has developed and tested the first prototype of its Roman Pots to be operated in the LHC. TOTEM Roman Pots contain stacks of silicon detectors with strips oriented in two orthogonal directions. To measure proton scattering angles of a few microradians, the detectors will approach the beam centre to a distance of 10σ + 0.5 mm (= 1.3 mm). Dead space near the detector edge is minimised by using two novel "edgeless" detector technologies. The silicon detectors are used both for precise track reconstruction and for triggering. The first full-sized prototypes of both detector technologies as well as their read-out electronics have been developed, built and operated. The tests took place in the proton beam-line of the SPS accelerator ring. In addition, the pot's shielding against electromagnetic interference and the longitudinal beam coupling impedance have been measured with the wire method.

The TOTEM experiment intends to measure the total proton proton cross-section at 14 TeV and the LHC luminosity with a precision of ≤ 5 % in short runs with a special β* = 90 m optics at an early stage of LHC operation. Furthermore, this will allow a measurement of the elastic proton proton scattering cross-section in a |t|-range from 0.04 to 1 GeV2, a study of soft proton proton diffraction with a large diffractive proton acceptance as well as provide precise information on the horizontal distribution of the proton proton interaction vertices.

The odderon observation recently published by the D0 and TOTEM collaborations has been widely accepted by a majority of the particle physics community and its importance recognized through dedicated physics seminars in the world major labs and physics institute. Naturally also some questions and objections have been raised, either privately or publicly, in discussion sessions and articles. In this proceedings article, a comprehensive list of these questions and objections are answered and supplementary material is provided. The methods and assumptions used in the extrapolation of the $pp$ elastic differential cross section to $\sqrt{s}$ = 1.96 TeV and its comparison to the D0 measurement in $p\bar{p}$ are shown to be valid and reasonable. Likewise, the methods and choices used for the $\rho$ measurement at LHC. Furthermore, objections against the odderon interpretation are demonstrated not to be valid. Finally, the combination of the different odderon significances, leading to the first experimental observation of odderon exchange, is shown to be well founded.

All four LEP experiments are equipped with vertex detectors based on silicon microstrip sensors. Most of them were upgraded to meet the requirements of LEP2, having the Higgs boson search as a prime target. This article reviews these detectors and focuses on their performances at LEP2. Aspects concerning alignment and geometrical stability are also discussed.

The authors propose to add high precision track detectors 55 m downstream on both (E and W) sides of CDF, to measure high Feynman-x protons and antiprotons in association with central states. A primary motivation is to search for the Higgs boson, and if it is seen to measure its mass precisely. The track detectors will be silicon strip telescopes backed up by high resolution time-of-flight counters. They will have four spectrometer arms, for both sides of the p and {bar p} beams. The addition of these small detectors effectively converts the Tevatron into a gluon-gluon collider with {radical}s from 0 to {approx} 200 GeV. This experiment also measures millions/year clean high- |t| elastic p{bar p} scattering events and produce millions of pure gluon jets. Besides a wealth of other unique QCD studies they will search for signs of exotic physics such as SUSY and Large Extra Dimensions. They ask the Director to ask the PAC to take note of this Letter of Intent at its April meeting, to consider a proposal at the June meeting and to make a decision at the November 2001 meeting. They request that the Directorage ask the Beams Division to evaluate the consequences and cost of the proposed Tevatron modifications, and CDF to evaluate any effect on its baseline program and to review the technical aspects of the detectors, DAQ and trigger integration.

The internal shape and alignment of accelerator discs is crucial for efficient collider operation in the possible future compact linear collider. We applied a custom made and calibrated Fourier domain short coherence interferometer to measure the height of 40 and 60 &mu;m machined steps on a copper disc in our laboratory. The step heights were determined to be: (43.0 &plusmn; 3.1) &mu;m and (46.5 &plusmn; 3.2) &mu;m for the 40 &mu;m nominal step, and (46.6 &plusmn; 3.6) μm for the 60 &mu;m nominal step. The errors represent 95% confidence level uncertainties and include uncertainty contributions from the calibration, refractive index of air, cosine error, and surface roughness. The step heights were validated by a calibrated contact stylus profilometer which resulted into (44.5 &plusmn; 0.8) &mu;m and (45.9 &plusmn; 1.0) μm for the 40 μm nominal step, and (45.5 &plusmn; 1.7) &mu;m for the 60 &mu;m nominal step at 95% confidence level. The results show feasibility for noncontacting absolute shape and step height characterization with micrometer-level accuracy. This instrument is a first step towards a quality assurance tester for the accelerating structures of the compact linear collider.

The TOTEM experiment is dedicated to the measurement of the total proton-proton cross-section with the luminosity-independent method and the study of elastic and diffractive scattering processes. Two tracking telescopes, T1 and T2, integrated in the CMS detector, cover the pseudo-rapidity region between 3.1 and 6.5 on both sides of the interaction point IP5. The Roman Pot (RP) stations are located at distances of ± 147m and ± 220 m with respect to the interaction point to measure the very forward scattered protons at very small angles. During the LHC technical stop in winter 2010/2011, the TOTEM experiment was completed with the installation of the T1 telescope and the RP stations at ± 147 m. In 2011, the LHC machine provided special optics with the large ß* = 90 m, allowing TOTEM to measure the elastic scattering differential cross section, down to the four-momentum transfer squared |t| = 2×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−2</sup> GeV <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . Using the optical theorem and extrapolation of the differential cross section to t = 0 (optical point), the total p-p cross section at the LHC energy of √v = 7 TeV could be computed for the first time. The status of the experiment, the performance of the detectors with emphasis on the RPs are described and the first physics results are presented.

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 &lt; eta &lt; 4.7 and -6.95 &lt; eta &lt; -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 p_T &gt; 0 MeV/c, produced in inelastic interactions with at least one charged particle in -7 &lt; eta &lt; -6 or 3.7 &lt; eta &lt;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.

A two-dimensional single sided Si strip detector using cross connected short strips interleaved with long strips has been designed. In the design, the z coordinate (along the strips) can be measured by finding the crossing point of the strips. No sacrifice is necessary on the r phi coordinate resolution in the design.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The Compact Linear Collider (CLIC) is currently under development at CERN as a potential multi-TeV e + e – collider. The manufacturing and assembly tolerances for the required RF components are essential for the final efficiency and for the operation of CLIC. The proper function of an accelerating structure is sensitive to mechanical errors in the shape and the alignment of the accelerating cavity. The current tolerances are in the micron range. This raises challenges in the field of mechanical design and demands special manufacturing technologies and processes. Currently the mechanical design of the accelerating structures is based on a disk design. Alternatively, it is possible to create the accelerating assembly from quadrants, which has the potential to be favoured for the mass production due to simplicity and cost. In this case, the functional shape inside of the accelerating structure remains the same and a single assembly uses less parts. This paper focuses on the development work done in design and simulation for prototype accelerating structures and describes its application to series production.

Proton-proton elastic scattering has been measured by the TOTEM experiment at the CERN Large Hadron Collider at $\sqrt{s} = 7 $ TeV in special runs with the Roman Pot detectors placed as close to the outgoing beam as seven times the transverse beam size. The differential cross-section measurements are reported in the |t|-range of 0.36 to 2.5 GeV^2. Extending the range of data to low t values from 0.02 to 0.33 GeV^2,and utilizing the luminosity measurements of CMS, the total proton-proton cross section at sqrt(s) = 7 TeV is measured to be (98.3 +- 0.2(stat) +- 2.8(syst)) mb.

A study of a possible layout of a Silicon tracker has been done. The design is based on simulations done in the context of the Compact Muon Solenoid (CMS) detector for the LHC. The high granularity of the silicon strip detectors yields to low occupancies. New type of a silicon strip detector, single sided stereo angle detector (SSSD), has been designed to match the requirements of a LHC tracker. This detector allows a z-coordinate measurement without increasing the number of channels i.e. power consumption and it facilitates a tracker design with reasonable complicity.

Abstract An unusual strain of coagulase-positive, penicillin-resistant staphylococcus was isolated repeatedly from the blood of a patient with bacterial endocarditis involving the aortic valve. Although improvement occurred following antibiotic therapy, the patient died of congestive failure. Studies of this unique strain revealed that growth was maximal only in the presence of added CO 2 and that dwarf colonies were produced on the surface of agar plates. The strain had attenuated virulence when tested in mice. The characteristics of this strain were reproducible after repeated subcultures, indicating its stability. It is suggested that such strains might arise more often than realized as a result of exposure to antibiotics.

The physics goals at the future e+e- linear collider require high performance vertexing and impact parameter resolution. Two possible technologies for the vertex detector of an experimental apparatus are outlined in the paper: an evolution of the Hybrid Pixel Sensors already used in high energy physics experiments and a new detector concept based on the monolithic CMOS sensors.

TOTEM is dedicated experiment at the LHC to the measurements of total cross-section, elastic scattering and diffraction. Elastically and diffractively scattered protons are measured in Roman Pots and charged particles by the T1 and T2 telescopes in the pseudorapidity range 3.1 to 6.5. TOTEM has measured the luminosity-independent total, elastic and inelastic proton-proton crosssections at √ s = 7 TeV and 8 TeV using low-pileup runs with a dedicated β ∗ = 90 m optics. At √ s = 7 TeV, the cross-sections were also determined using the CMS luminosity giving results that are in excellent agreement with the luminosity-independent ones, despite having very different systematic dependencies. Moreover, since TOTEM is capable to detect diffractive events with masses down to 3.4 GeV, a limit on the cross section for low mass diffraction has been set from the difference between the overall inelastic cross section (measured only using elastic scattering) and visible inelastic cross section (measured using T1 and T2). The differential elastic protonproton cross section has been measured over a wide range in |t| for √ s = 7 TeV. TOTEM has also determined double diffractive cross-section in the forward region at √ s = 7 TeV as well as studied soft single diffraction. In addition, TOTEM has performed an inclusive forward charged particle pseudorapdity density measurement in 7 TeV proton-proton collisions for the range 5.3 < |η| < 6.4 using T2. Next, TOTEM will together with CMS measure the charged particle pseudorapidity density at √ s = 8 TeV simultaneously in the central (CMS tracker) and forward (T2) region.

Abstract A telescope designed for the study of position sensitive detectors has been used for beam position monitoring. The telescope consists of eight silicon strip detectors and it is installed in the RD5 experiment at CERN. The telescope was tested with pion and muon beams in the energy range between 30 and 300 GeV/ c in the North Area of the SPS accelerator. The best impact point errors were 2.5 μm in the vertical and 2.9 μm in the horizontal direction. The signal-to-noise ratios of the detectors were around 40 and the efficiencies above 96%. The alignment of the telescope was very accurate and the correction for possible tilts did not essentially improve the performance.

The luminosity goal of the CLIC collider, currently under study, imposes micrometer mechanical stability of the 2-m long two-beam modules, the shortest repetitive elements of the main linacs. These modules will be exposed to variable high power dissipation during operation resulting in mechanical distortions in and between module components. The stability of the CLIC module will be tested in laboratory conditions at CERN in a full-scale prototype module. In this paper, the FEA model developed for CLIC prototype module is described. The thermal and structural results for the new module configuration are presented considering the thermo-mechanical behavior of the CLIC collider in its primary operation modes. These results will be compared to the laboratory measurements to be done during 2011 and 2012 with the full-scale prototype module. The experimental results will allow for better understanding of the module behaviour and they will be propagated back to the present thermo-mechanical model.

Micron-level stability of the Compact LInear Collider (CLIC) two-beam modules, two-meter repetitive units constituting the main linacs, is one of the most important requirements to achieve the final luminosity target. High power dissipation during normal operation modes of modules will result in misalignments in and between different elements of the linacs, thus affecting the final resulting luminosity. In this paper, updated finite element models of CLIC two-beam modules are presented and the structural behaviour of them is studied in more detail than in the earlier simulations. In particular, the models have been refined by improving the modelling of actuators and bellows as well as studying the most updated versions of CLIC modules. Based on the main operation modes of the CLIC collider, the results of thermal and structural analysis of two-beam modules are presented. These numerical results will be validated by experimental tests to be performed in 2012 with full-scale CLIC prototype modules. They will allow for better understanding the thermo-mechanical behaviour and they will be propagated back to numerical modelling.

The first physics results from the TOTEM experiment are here reported, concerning the measurements of the total, differential elastic, elastic and inelastic pp cross-section at the LHC energy of $\sqrt{s}$ = 7 TeV, obtained using the luminosity measurement from CMS. A preliminary measurement of the forward charged particle $\eta$ distribution is also shown.

TOTEM is an experiment designed to perform total cross section, elastic scattering, and diffractive dissociation measurements at the LHC. It is made up of elastic detectors set in the tunnel (Roman Pots) and two inelastic telescopes: T1 and T2, located in the same cavern as the CMS experiment. The T2 telescope is placed at the very forward region of the CMS's detector, in a high radioactive environment, as revealed by measurements performed using radiation sensors. The amount of particles produced in the interaction with material in front of and around the detector was found to be particularly challenging for both detector performances and physics analysis. The offline software developed for the reconstruction of inelastic events tracks is briefly described. Internal and general alignments of the telescopes have been another complex issue: the strategy to correct the misalignment biases are explained. A preliminary measurements of the forward charged particle η distribution performed by T2 is also presented.

The first physics results from the TOTEM experiment are here reported, concerning the measurements of the total, differential elastic, elastic and inelastic pp cross-section at the LHC energy of $\sqrt{s}$ = 7 TeV, obtained using the luminosity measurement from CMS. A preliminary measurement of the forward charged particle $η$ distribution is also shown.

Silicon strip detectors with double-sided readout have been designed and processed on 100-mm silicon wafers. Detectors with integrated coupling capacitors and polysilicon bias resistors were tested by static electrical measurements. A detector with VLSI readout electronics was measured in a test beam. Test beam measurements show signal over noise ratios of 39 on the detector p-side and 26 on the n-side.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The papers review the main theoretical and experimental aspects of the Forward Physics at the Large Hadron Collider.

V. Avati , M. Berretti, M. Besta, E. Brucken, P. Dadel, F. Ferro, F. Garcia, S. Giani, L. Grzanka, J. Hallila, P. Janhunen , J. Kaspar, G. Latino, R. Leszko, D. Mierzejewski, H. Niewiadomski, T. Novak, T. Nuotio, E. Oliveri, K. Osterberg, F. Oljemark, S. Sadilov, M. Tuhkanen , T. Vihanta, M. Zalewski, Z. Zhang, J. Welti Case Western Reserve University, Dept. of Physics, Cleveland, OH, USA CERN, Geneve, Switzerland Helsinki Institute of Physics and Dept. of Physics, University of Helsinki,Finland Institute of Physics of the Academy of Sciences, Praha, Czech Republic MTA KFKI RMKI, Budapest, Hungary INFN Sezione di Genova, Italy Universita di Siena and INFN Sezione di Pisa, Italy On leave from AGH Univ. of Sci. and Technology, Krakow, Poland On leave from University of Applied Sciences, Rovaniemi, Finland ∗Corresponding Author E-mail: valentina.avati@cern.ch

The TOTEM experiment at the LHC measures the total proton-proton cross section with the luminosity-independent method and the elastic proton-proton cross-section over a wide |t|-range. It also performs a comprehensive study of diffraction, spanning from cross-section measurements of individual diffractive processes to the analysis of their event topologies. Hard diffraction will be studied in collaboration with CMS taking advantage of the large common rapidity coverage for charged and neutral particle detection and the large variety of trigger possibilities even at large luminosities. TOTEM will take data under all LHC beam conditions including standard high luminosity runs to maximize its physics reach. This contribution describes the main features of the TOTEM physics programme including measurements to be made in the early LHC runs. In addition, a novel scheme to extend the diffractive proton acceptance for high luminosity runs by installing proton detectors at IP3 is described.

The purpose of the Low-$x$ Workshop series is to stimulate discussions between experimentalists and theorists in diffractive hadronic physics, QCD dynamics at low $x$, parton saturation, and exciting problems in QCD at HERA, Tevatron, LHC, RHIC, and the future EIC. The central topics of the workshop, summarized in the current Proceedings, were: Diffraction in ep and e-ion collisions (including EIC physics); Diffraction and photon-exchange in hadron-hadron, hadron-nucleus, and nucleus-nucleus collisions; Spin Physics; Low-$x$ PDFs, forward physics, and hadronic final states. This Workshop has been the XXVIII edition in the series of the workshop.

The TOTEM experiment at the LHC measures the total proton-proton cross section with the luminosity-independent method and the elastic proton-proton cross-section over a wide |t|-range. It also performs a comprehensive study of diffraction, spanning from cross-section measurements of individual diffractive processes to the analysis of their event topologies. Hard diffraction will be studied in collaboration with CMS taking advantage of the large common rapidity coverage for charged and neutral particle detection and the large variety of trigger possibilities even at large luminosities. TOTEM will take data under all LHC beam conditions including standard high luminosity runs to maximize its physics reach. This contribution describes the main features of the TOTEM physics programme including measurements to be made in the early LHC runs. In addition, a novel scheme to extend the diffractive proton acceptance for high luminosity runs by installing proton detectors at IP3 is described.

The momentum and angular distributions of punchthrough muons have been measured after a 10 λ calorimeter using an iron toroid magnet with 1.5 T as spectrometer. The calorimeter was inside a variable magnetic field of 0 to 3 T. The incident momentum of the π− beam ranged from 20 to 300 GeV/c. Measurements were also done at some beam momenta for π+, K+ and p. The results are compared with Monte Carlo predictions. A parameterization for the momentum spectrum of punchthrough muons was derived from the data.

At the Tevatron, the total p¯p cross-section has been measured by CDF at 546 GeV and 1.8TeV, and by E710/E811 at 1.8TeV. The two results at 1.8TeV disagree by 2.6 standard deviations, introducing big uncertainties into extrapolations to higher energies. At the LHC, the TOTEM collaboration is preparing to resolve the ambiguity by measuring the total pp cross-section with a precision of about 1%. Like at the Tevatron experiments, the luminosity-independent method based on the Optical Theorem will be used. The Tevatron experiments have also performed a vast range of studies about soft and hard diffractive events, partly with antiproton tagging by Roman Pots, partly with rapidity gap tagging. At the LHC, the combined CMS/TOTEM experiments will carry out their diffractive programme with an unprecedented rapidity coverage and Roman Pot spectrometers on both sides of the interaction point. The physics menu comprises detailed studies of soft diffractive differential cross-sections, diffractive structure functions, rapidity gap survival and exclusive central production by Double Pomeron Exchange.

The group refractive index is important in length calibration of Fourier domain interferometers by transparent transfer standards. We demonstrate accurate group refractive index quantification using a Fourier domain short coherence Sagnac interferometer. Because of a justified linear length calibration function, the calibration constants cancel out in the evaluation of the group refractive index, which is then obtained accurately from two uncalibrated lengths. Measurements of two standard thickness coverslips revealed group indices of 1.5426±0.0042 and 1.5434±0.0046, with accuracies quoted at the 95% confidence level. This agreed with the dispersion data of the coverslip manufacturer and therefore validates our method. Our method provides a sample specific and accurate group refractive index quantification using the same Fourier domain interferometer that is to be calibrated for the length. This reduces significantly the requirements of the calibration transfer standard.

The radiation hardness of diamond at the sensor level is studied by irradiating five sensors and studying them with various particle sources, without making any modifications to the sensors in between. The electronics used in the characterization is not irradiated to ensure that any observed effect is merely due to the sensor. Three sensors have received a fluence of 10 14 protons cm −2 and two 5⋅10 15 protons cm −2 . At the lower fluence, the impact on the charge collection efficiency is very small, when the applied bias voltage is above 1 V μm −1 . For the higher fluence, the charge collection efficiency is lower than expected based on earlier studies of diamond radiation hardness on the substrate level. Furthermore, it is noticed that the irradiation has a stronger impact on the signal amplitude recorded with a fast timing than with a charge sensitive amplifier.

The TOTEM experiment at the LHC has performed the first measurement at $\sqrt{s} = 13$ TeV of the $ρ$ parameter, the real to imaginary ratio of the nuclear elastic scattering amplitude at $t=0$, obtaining the following results: $ρ= 0.09 \pm 0.01$ and $ρ= 0.10 \pm 0.01$, depending on different physics assumptions and mathematical modelling. The unprecedented precision of the $ρ$ measurement, combined with the TOTEM total cross-section measurements in an energy range larger than 10 TeV (from 2.76 to 13 TeV), has implied the exclusion of all the models classified and published by COMPETE. The $ρ$ results obtained by TOTEM are compatible with the predictions, from alternative theoretical models both in the Regge-like framework and in the QCD framework, of a colourless 3-gluon bound state exchange in the $t$-channel of the proton-proton elastic scattering. On the contrary, if shown that the 3-gluon bound state $t$-channel exchange is not of importance for the description of elastic scattering, the $ρ$ value determined by TOTEM would represent a first evidence of a slowing down of the total cross-section growth at higher energies. The very low-$|t|$ reach allowed also to determine the absolute normalisation using the Coulomb amplitude for the first time at the LHC and obtain a new total proton-proton cross-section measurement $σ_{tot} = 110.3 \pm 3.5$ mb, completely independent from the previous TOTEM determination. Combining the two TOTEM results yields $σ_{tot} = 110.5 \pm 2.4$ mb.

In this contribution, we present a first systematic study of the precision of the momentum measurement of protons produced in the central exclusive diffractive processes, pp → p+X+p, as well as the accuracy of the reconstructed mass for particle state X based on these proton measurements. The scattered protons are traced along the LHC beam line using the nominal LHC optics, accounting for uncertainties related to beam transport and proton detection. To search for and precisely measure new particle states X with masses below 200 GeV, additional leading proton detectors are required at about 420 m from the interaction point in addition to the already approved detectors. Using these additional detectors, a mass resolution of the order of 1 GeV can be achieved for masses beyond ∼ 120 GeV.