A novel Monolithic Active Pixel Sensor (MAPS) for charged particle tracking made in a standard CMOS technology is proposed. The sensor is a photodiode, which is readily available in a CMOS technology. The diode has a special structure, which allows the high detection efficiency required for tracking applications. The partially depleted thin epitaxial silicon layer is used as a sensitive detector volume. Semiconductor device simulation, using either ToSCA based or 3-D ISE-TCAD software packages shows that the charge collection is efficient, reasonably fast (order of 100 ns), and the charge spreading limited to a few pixels only. A first prototype has been designed, fabricated and tested. It is made of four arrays each containing 64×64 pixels, with a readout pitch of 20 μm in both directions. The device is fabricated using standard submicron 0.6 μm CMOS process, which features twin-tub implanted in a p-type epitaxial layer, a characteristic common to many modern CMOS VLSI processes. Extensive tests made with soft X-ray source (55Fe) and minimum ionising particles (15 GeV/c pions) fully demonstrate the predicted performances, with the individual pixel noise (ENC) below 20 electrons and the Signal-to-Noise ratio for both 5.9 keV X-rays and Minimum Ionising Particles (MIP) of the order of 30. This novel device opens new perspectives in high-precision vertex detectors in Particle Physics experiments, as well as in other application, like low-energy beta particle imaging, visible light single photon imaging (using the Hybrid Photon Detector approach) and high-precision slow neutron imaging.

The backward region of the H1 detector has been upgraded in order to provide improved measurement of the scattered electron in deep inelastic scattering events. The centerpiece of the upgrade is a high-resolution lead/scintillating-fibre calorimeter. The main design goals of the calorimeter are: good coverage of the region close to the beam pipe, high angular resolution and energy resolution of better than 2% for 30 GeV electrons. The calorimeter should be capable of providing coarse hadronic energy measurement and precise time information to suppress out-of-time background events at the first trigger level. It must be compact due to space restrictions. These requirements were fulfilled by constructing two separate calorimeter sections. The inner electromagnetic section is made of 0.5 mm scintillating plastic fibres embedded in a lead matrix. Its lead-to-fibre ratio is 2.3:1 by volume. The outer hadronic section consists of 1.0 mm diameter fibres with a lead-to-fibre ratio of 3.4:1. The mechanical construction of the new calorimeter and its assembly in the H1 detector are described.

In a study ofpp collisions at $$\sqrt s = 63$$ GeV with more than 29 GeV total transverse energy emitted into 1.8 units of rapidity in the central region, we have extracted a sample of 4-jet events and compared it with models of the two sources of 4-jet production: double bremsstrahlung and double parton scattering. The data cannot be described by bremsstrahlung alone, and we extract the fraction of 4-jet events attributed to double parton scattering for various definitions of the 4-jet sample. We determine the double parton scattering/2-jet yield ratio, and this leads to a determination of the proton radius. We discuss the implications of our observations for the general understanding of high-ΣE T events.

The CMS detector at the CERN LHC features a silicon pixel detector as its innermost subdetector. The original CMS pixel detector has been replaced with an upgraded pixel system (CMS Phase-1 pixel detector) in the extended year-end technical stop of the LHC in 2016/2017. The upgraded CMS pixel detector is designed to cope with the higher instantaneous luminosities that have been achieved by the LHC after the upgrades to the accelerator during the first long shutdown in 2013–2014. Compared to the original pixel detector, the upgraded detector has a better tracking performance and lower mass with four barrel layers and three endcap disks on each side to provide hit coverage up to an absolute value of pseudorapidity of 2.5. This paper describes the design and construction of the CMS Phase-1 pixel detector as well as its performance from commissioning to early operation in collision data-taking.

We present results from a study of centrally produced mesons in 3 × 106 events with two small-angle protons at the CERN Intersecting Storage Rings. A high-statistics sample of exclusive pp → ppπ+π− events at √s = 63 GeV has been obtained, where the reaction mechanism is dominated by double pomeron exchange. Scalar or tensor glueballs may be produced by this process. The π+π− mass spectrum has a distinctive structure, and analysis shows that the data are dominantly S-wave up to 1600 MeV. The behaviour of the D-wave provides evidence for a 2++ resonance (M = 1480 ± 50 MeV, Γ = 150 ± 50 MeV) in addition to the f(1270). We also show data on exclusive K+K−, pp, and π+π−π+π− production, and on the analogous reaction αα → ααπ+π− at √s = 126 GeV. Flavour independence is suggested by the observation of approximately equal numbers of K+K− and π+π− pairs for mass above 1 GeV. The mass spectra are also apparently independent of √s (45, 63, 126 GeV) and incident particle type (p, α).

The result of a search at the LHC for heavy stable charged particles produced in pp collisions at $ \sqrt {s} = 7\;{\text{TeV}} $ is described. The data sample was collected with the CMS detector and corresponds to an integrated luminosity of 3.1 pb−1. Momentum and ionization-energy-loss measurements in the inner tracker detector are used to identify tracks compatible with heavy slow-moving particles. Additionally, tracks passing muon identification requirements are also analyzed for the same signature. In each case, no candidate passes the selection, with an expected background of less than 0.1 events. A lower limit at the 95% confidence level on the mass of a stable gluino is set at 398GeV/c 2, using a conventional model of nuclear interactions that allows charged hadrons containing this particle to reach the muon detectors. A lower limit of 311 GeV/c 2 is also set for a stable gluino in a conservative scenario of complete charge suppression, where any hadron containing this particle becomes neutral before reaching the muon detectors.

Hadronic event shapes have been measured in proton-proton collisions at sqrt(s)=7 TeV, with a data sample collected with the CMS detector at the LHC. The sample corresponds to an integrated luminosity of 3.2 inverse picobarns. Event-shape distributions, corrected for detector response, are compared with five models of QCD multijet production.

A measurement of the top-antitop production cross section in proton-proton collisions at a centre-of-mass energy of 7 TeV has been performed at the LHC with the CMS detector. The analysis uses a data sample corresponding to an integrated luminosity of 36 inverse picobarns and is based on the reconstruction of the final state with one isolated, high transverse-momentum electron or muon and three or more hadronic jets. The kinematic properties of the events are used to separate the top-antitop signal from W+jets and QCD multijet background events. The measured cross section is 173 + 39 - 32 (stat. + syst.) pb, consistent with standard model expectations.

The charge asymmetry in the production of top quark and antiquark pairs is measured in proton-proton collisions at a center-of-mass energy of 8 TeV. The data, corresponding to an integrated luminosity of 19.6 inverse femtobarns, were collected by the CMS experiment at the LHC. Events with a single isolated electron or muon, and four or more jets, at least one of which is likely to have originated from hadronization of a bottom quark, are selected. A template technique is used to measure the asymmetry in the distribution of differences in the top quark and antiquark absolute rapidities. The measured asymmetry is A[c,y] = [0.33 +/- 0.26 (stat) +/- 0.33 (syst)]%, which is the most precise result to date. The results are compared to calculations based on the standard model and on several beyond-the-standard-model scenarios.

The properties of final modules of a high resolution lead/scintillating-fibre calorimeter to upgrade the backward region of the H1 detector were studied with electrons in the energy range from 2–60 GeV. The electromagnetic calorimeter consists of scintillating fibres with a diameter of 0.5 mm embedded in a lead matrix. This small fibre radius, in combination with a lead-to-fibre ratio of 2.27:1, ensures excellent energy resolution which has been measured to be δ/E=7.1%/ E/GeV ⊕ 1.0%. The spatial resolution as a function of energy for impact points at the center of a cell is given by 4.4 mm/ E/GeV + 1.0 mm. The time resolution was found to be better than 0.4 ns.

Bose-Einstein correlations between pions produced in the central region of rapidity in αα, pp and pp interactions have been studied at the ISR. The parameters r and τ c -often interpreted as the radius and depth of the π-emitting region - are found to be independent of incident particle type but to depend on the mean charged multiplicity. In high multiplicity events, the pions appear to originate from a larger space-time region.

The HELIOS experiment has measured inclusivep ⊥ spectra of negative particles in the rapidity region 1.0<y<1.9. The general shape of thep ⊥ spectra in p +W, O+W and S+W is similar, but cannot be described by a single exponential. Compared to p+p collisions, an excess is observed for low and highp ⊥. This effect increases with the projectile mass. Except for very lowE ⊥, the average transverse momentum <p ⊥> is found to be approximately constant up to the highest accessible values ofE ⊥.

The differential cross section for production of jets in pp interactions at y = 0 and pT from 6–12 GeV/c has been measured at √s = 45 GeV at the CERN Intersecting Storage Rings and compared with a previous measurement at √s = 63 GeV. The data were obtained using a 2.1 sr hadron calorimeter which was triggered on transverse energy. The energy dependence of the jet cross section is well described by (1−xT)mpT−n, with m = 10.6±1.0 and n = 5.3±0.2. The results are in good agreement with predictions obtained from a QCD-motivated model.

In pp and pp̄ collisions at the CERN Intersecting Storage Rings, a directional dependence of the size of the pion-emitting region is observed using Bose-Einstein interference between identical charged pions. The data reveal a substantially larger dimension in the direction parallel to the beam axis than in the transverse direction, indicating a prolate shape of the emission region. For αα interactions, the data are consistent with a spherical shape.

We have observed an enhanced production of pairs and triplets of identical charged particles at small momentum differences in events with two central jets produced inpp collisions at the CERN Intersecting Storage Rings. The size and structure of this ‘Bose-Einstein’ enhancement, shown by the particles within a jet, resembles that observed in minimum-bias events. The correlation function can be well parametrized by the single variableQ — the absolute value of the four-momentum transfer — and is more peaked than a single Gaussian.

Using annihilation in a calorimeter as a trigger on antiprotons, we have measured the relative production cross sections of p, Λ and Ξ at y∼0 in the transverse momentum range 1 to 2 GeV/c in pp collisions at √s=63 GeV. We investigate correlations between the antibaryons and associated produced particles, and find evidence for local baryon number conservation.

Events with a large transverse energy in a calorimeter with full azimuthal coverage and |y| < 0.9 have been investigated in pp collisions at √s = 30, 45, and 63 GeV. A striking change in the event structure, corresponding to a clear emergence of high-pT jets, is observed at √s = 63 and 45 GeV in the region between 25 and 35 GeV in transverse energy. At √s = 30 GeV, the data extend to ET ∼ 20 GeV, but no such change in the event structure is observed.

We present first results from a study of the exclusive reaction pp→pπ+π−p at √s=63 GeV with π+ and π− produced in the central region. This reaction has been suggested as a method of searching for gluonium states. The π+π− mass distribution shows rapid order of magnitude decreases in cross section at both 1000 MeV/c2 and 1500 MeV/c2. Further structure is observed above 2000 MeV/c2.

We have measured the production of direct photons, π0's, and η's in pp and pp collisions at √s=53 GeV in the range 2≈pT≈6 GeV/c for the central rapidity region |y| 0.4. No statistically significant difference between pp̄ and pp interactions is observed.

We report on the production of low-mass electron pairs and muon pairs in p-Be collisions at 450 GeV/c at the CERN SPS. For both electron and muon pairs the low-mass spectrum can be explained satisfactorily by lepton pairs from hadronic decays, and there is no need to invoke any "unconventional" source. The normalisation of the major hadronic sources is set by the data. The upper limit, at 90% confidence level, on any new source of lepton pairs is ∼20% of the hadronic decay contribution for muons, and ∼40% for electrons.

A search for non-statistical fluctuations was performed in 200 GeV per nucleon oxygen and sulphur ion-emulsion interactions selected by a high transverse energy trigger. No clear signal of dynamical correlations or of unusual fluctuations was found.

Transverse-energy distributions have been measured for the collisions of the 32S nucleus with Al, Ag, W, Pt, Pb, and U target nuclei, at an incident energy of 200 GeV per nucleon. The shapes of these distribution reflect the geometry of the collisions, including the deformation effects. For central collisions, the transverse-energy production in the region −0.1<ηlab<2.9 increases approximately as A0.5, where A is the atomic mass number of the target. This increase is accompanied by a relative depletion in the forward region ηlab > 2.9. These results are compared with those obtained under similar conditions with incident 16O nuclei. A comparison is also made with the predictions of a Monte Carlo generator based on the dual parton model. Finally, we give estimates of the energy density reached and its dependence on the atomic mass number of the projectile.

Conversion electrons from electromagnetic transitions preceding the fission decay of the shape isomers $^{236,238}\mathrm{U}$ have been measured. For both isomers highly converted transitions are observed which are tentatively interpreted as the decay of the lowest $\ensuremath{\beta}$-vibrational band, via $E0$ transitions, at excitation energies of 686.0\ifmmode\pm\else\textpm\fi{}0.7 and 647.8\ifmmode\pm\else\textpm\fi{}0.9 keV, respectively.

We are proposing a mission devoted to high energy X-ray astronomy that is based on a focusing telescope operating in the 1–200 keV energy range but optimized for the hard X-ray range. The main scientific topics concern: Physics of compact objects: The proximity of compact objects provides a unique laboratory to study matter and radiation in extreme conditions of temperature and density in strong gravitational environment. The emission of high energy photons from these objects is far from being understood. The unprecedented sensitivity in the high energy domain will allow a precise determination of the non-thermal processes at work in the vicinity of compact objects. The full 1–200 keV energy coverage will be ideal to disentangle the emission processes produced in the spacetime regions most affected by strong-gravity, as well as the physical links: disk–thermal emission–iron line–comptonisation–reflection–non-thermal emission–jets. Neutron stars–magnetic field–cyclotron lines: Time resolved spectroscopy (and polarimetry) at ultra-high sensitivity of AXP, milliseconds pulsars and magnetars will give new tools to study the role of the synchrotron processes at work in these objects. Cyclotron lines–direct measurement of magnetic filed–equation of state constraints–short bursts–giant flares could all be studied with great details. AGN: The large sensitivity improvement will provide detailed spectral properties of the high energy emission of AGN’s. This will give a fresh look to the connection between accretion and jet emission and will provide a new understanding of the physical processes at work. Detection of high-redshift active nuclei in this energy range will allow to introduce an evolutionary aspect to high-energy studies of AGN, probing directly the origin of the Cosmic X-ray Background also in the non-thermal range (> 20 keV). Element formation–Supernovae: The energy resolution achievable for this mission (<0.5 keV) and a large high energy effective area are ideally suited for the 44Ti line study (68 and 78 keV). This radioactive nuclei emission will give an estimate of their quantities and speed in their environment. In addition the study of the spatial structure and spectral emission of SNR will advance our knowledge of the dynamics of supernovae explosions, of particles acceleration mechanisms and how the elements are released in the interstellar medium. Instrumental design: The progress of X-ray focusing optics techniques allows a major step in the instrumental design: the collecting area becomes independent of the detection area. This drastically reduces the instrumental background and will open a new era. The optics will be based on depth-graded multi-layer mirrors in a Wolter I configuration. To obtain a significant effective area in the hundred of keV range a focal length in the 40–50 meters range (attainable with a deployable mast) is needed. In addition such a mission could benefit from recent progress made on mirror coating. We propose to cover the 1–200 keV energy range with a single detector, a double-sided Germanium strip detector operating at 80 K. The main features will be: (a) good energy resolution (.150 keV at 5 keV and <.5 keV at 100 keV), (b) 3 dimensional event localization with a low number of electronic chains, (c) background rejection by the 3D localization, (d) polarisation capabilities in the Compton regime.

We present stdies of events triggered on two high-p T jets, produced inpp collisions at the CERN Intersecting Storage Rings (ISR) at $$\sqrt s $$ =63 GeV, using a large solid angle calorimeter. The cross-section for producing two jets is measured in the dijet mass range 17–50 GeV/c2. A high-statistics sample of dijet events, where each jet has transverse energy above 10 GeV, is used to study the structure of jets and the associated event. We find the longitudinal fragmentation function to be similar to that of jets emerging frome + e − collisions but considerably harder than that observed at the Super Proton Synchrotron (SPS) $$p\bar p$$ Collider. A steepening of the fragmentation function is observed when increasing the jet energy. Studies of the charge distribution in jets show that these predominantly originate from fragmenting valence quarks. The transverse energy and particle flows are presented as functions of the azimuthal distance from the jet axis.

The production of inclusive prompt positrons in pp collisions at √s = 63 GeV and θcm = 90° has been measured over the pT interval 0.08 <pT < 1.0 GeVc. The e/π ratio rises from ∼ 2 × 10−4 at pT = 0.9 GeVc to ∼ 1 × 10−3 at pT = 0.1 GeVc. This is a factor of 6 higher than would be expected from the sum of hadronic bremsstrahlung and the semileptonic decay of charm.

We have measured the production of prompt positrons in pp collisions at √s = 63 GeV and y = 0 in the pT interval 0.12<pT<1.0 GeV/c. The results indicate that the production of positrons at low pT (<0.4 GeV/c) is proportional to the square of the mean multiplicity in the central region |y| < 1. Such a quadratic dependence is not expected from final-state sources such as hadronic bremsstrahlung or hadronic decays, but is natural in models where low mass electron pairs are produced by interactions of constituents created during the collision.

Bose-Einstein correlations between identical charged kaons are observed in αα, pp, and pp collisions at the CERN Intersecting Storage Rings. The average radial extension of the K-enitting region is found to be (2.4±0.9) fm.

The transverse energy distributions have been measured for interactions of 32S nuclei with Al, Ag, W, Pt, Pb, and U targets, at an incident energy of 200 GeV per nucleon in the pseudorapidity region −0.1 < νlab < 5.5. These distributions are compared with those for 16OW interactions in the same pseudorapidity region and with earlier measurements performed with 16O and 32S projectiles in the region −0.1 < νlab < 2.9. These comparisons provide both a better understanding of the dynamics involved and improved estimates of stopping power and energy density.

Abstract The CMS Inner Tracker, made of silicon pixel modules, will be entirely replaced prior to the start of the High Luminosity LHC period. One of the crucial components of the new Inner Tracker system is the readout chip, being developed by the RD53 Collaboration, and in particular its analogue front-end, which receives the signal from the sensor and digitizes it. Three different analogue front-ends (Synchronous, Linear, and Differential) were designed and implemented in the RD53A demonstrator chip. A dedicated evaluation program was carried out to select the most suitable design to build a radiation tolerant pixel detector able to sustain high particle rates with high efficiency and a small fraction of spurious pixel hits. The test results showed that all three analogue front-ends presented strong points, but also limitations. The Differential front-end demonstrated very low noise, but the threshold tuning became problematic after irradiation. Moreover, a saturation in the preamplifier feedback loop affected the return of the signal to baseline and thus increased the dead time. The Synchronous front-end showed very good timing performance, but also higher noise. For the Linear front-end all of the parameters were within specification, although this design had the largest time walk. This limitation was addressed and mitigated in an improved design. The analysis of the advantages and disadvantages of the three front-ends in the context of the CMS Inner Tracker operation requirements led to the selection of the improved design Linear front-end for integration in the final CMS readout chip.

We have measured the inclusivep T spectra of soft photons produced at central and backward rapidities in 450 GeV/cp-Be collisions down to 1 MeV/c in transverse momentum. In the region 1<p T <20 MeV/c an excess of photons over those expected from hadronic decays is observed. This excess is comparable, within systematic errors, with estimates of direct photons produced via hadronic bremsstrahlung. An upper limit is derived on the presence of additional sources of direct photons at small transverse momentum.

Diffractive dissociation of nuclei (Be, Al, W) in collisions with 450 GeV/c protons,pA→pX, has been measured with the HELIOS spectrometer at the CERN Super Proton synchrotron. The dependence of the single-diffraction cross-section on the nuclear massA can be parametrized as σSD mb×A 0.35±0.02, showing the peripheral nature of the process. The differential cross-section dσSD=(3.8±0.3)mb ×A 0.35±0.02, is exponential with the slope parameter, increasing from 6.2±0.4 (GeV/c)−2 for beryllium to 7.9±0.5 (GeV/c)−2 for tungsten. The slope parameter also increases with increasing massM X of the diffractively produced state. The rapidity, multiplicity, and transverse-momentum distributions of the particles of the diffractively produced stateX show a longitudinal phase-space population and are remarkably insensitive to the nuclear mass. This, together with theA 1/3 dependence of σSD, suggests that the dominant process of nuclear diffractive excitation is the dissociation of single nucleons.

During summer 2006 a fraction of the CMS silicon strip tracker was operated in a comprehensive slice test called the Magnet Test and Cosmic Challenge (MTCC). At the MTCC, cosmic rays detected in the muon chambers were used to trigger the readout of all CMS sub-detectors in the general data acquisition system and in the presence of the 4 T magnetic field produced by the CMS superconducting solenoid. This document describes the operation of the Tracker hardware and software prior, during and after data taking. The performance of the detector as resulting from the MTCC data analysis is also presented.

A new CMS tracker detector will be installed for operation at the High Luminosity LHC (HL-LHC). This detector comprises modules with two closely spaced parallel sensor plates and front-end ASICs capable of transmitting tracking information to the CMS Level-1 (L1) trigger at the 40 MHz beam crossing rate. The inclusion of tracking information in the L1 trigger decision will be essential for selecting events of interest efficiently at the HL-LHC. The CMS Binary Chip (CBC) has been designed to read out and correlate hits from pairs of tracker sensors, forming so-called track stubs. For the first time, a prototype irradiated module and a full-sized module, both equipped with the version 2 of the CBC, have been operated in test beam facilities. The efficiency of the stub finding logic of the modules for various angles of incidence has been studied. The ability of the modules to reject tracks with transverse momentum less than 2 GeV has been demonstrated. For modules built with irradiated sensors, no significant drop in the stub finding performance has been observed. Results from the beam tests are described in this paper.

To cope with the challenging environment of the planned high luminosity upgrade of the Large Hadron Collider (HL-LHC), scheduled to start operation in 2029, CMS will replace its entire tracking system. The requirements for the tracker are largely determined by the long operation time of 10 years with an instantaneous peak luminosity of up to 7.5 × 1034 cm−2 s−1 in the ultimate performance scenario. Depending on the radial distance from the interaction point, the silicon sensors will receive a particle fluence corresponding to a non-ionising energy loss of up to Φeq= 3.5 × 1016 cm−2. This paper focuses on planar pixel sensor design and qualification up to a fluence of Φeq = 1.4 × 1016 cm−2.For the development of appropriate planar pixel sensors an R&D program was initiated, which includes n+-p sensors on 150 mm (6”) wafers with an active thickness of 150 µm with pixel sizes of 100×25 µm2 and 50×50 µm2 manufactured by Hamamatsu Photonics K.K. (HPK). Single chip modules with ROC4Sens and RD53A readout chips were made. Irradiation with protons and neutrons, as well was an extensive test beam campaign at DESY were carried out. This paper presents the investigation of various assemblies mainly with ROC4Sens readout chips. It demonstrates that multiple designs fulfil the requirements in terms of breakdown voltage, leakage current and efficiency. The single point resolution for 50×50 µm2 pixels is measured as 4.0 µm for non-irradiated samples, and 6.3 µm after irradiation to Φeq = 7.2 × 1015 cm−2.

Abstract The Large Hadron Collider at CERN will undergo an upgrade in order to increase its luminosity to 7.5 × 10 34 cm -2 s -1 . The increased luminosity during this High-Luminosity running phase, starting around 2029, means a higher rate of proton-proton interactions, hence a larger ionizing dose and particle fluence for the detectors. The current tracking system of the CMS experiment will be fully replaced in order to cope with the new operating conditions. Prototype planar pixel sensors for the CMS Inner Tracker with square 50 μm × 50 μm and rectangular 100 μm × 25 μm pixels read out by the RD53A chip were characterized in the lab and at the DESY-II testbeam facility in order to identify designs that meet the requirements of CMS during the High-Luminosity running phase. A spatial resolution of approximately 3.4 μm (2 μm) is obtained using the modules with 50 μm × 50 μm (100 μm × 25 μm) pixels at the optimal angle of incidence before irradiation. After irradiation to a 1 MeV neutron equivalent fluence of Φ eq = 5.3 × 10 15 cm -2 , a resolution of 9.4 μm is achieved at a bias voltage of 800 V using a module with 50 μm × 50 μm pixel size. All modules retain a hit efficiency in excess of 99% after irradiation to fluences up to 2.1 × 10 16 cm -2 . Further studies of the electrical properties of the modules, especially crosstalk, are also presented in this paper.

Inclusive photonp ⊥ spectra were measured with 200 GeV/u proton,16O and32S beams on W and Pt targets, using a conversion method. The measurement of charged pions in the same apparatus allows a comparison of the γ data with the expected γ's from hadronic decays π0, η, η', ω). In all data sets, no deviation from the expected shape is observed in the range of 0.1<p ⊥<1.5 GeV/c. The number of photons normalized to pions agrees within the statistical (4%–11%) and systematical (9%) errors with the number of photons expected from hadronic decays in the integrated ranges ranges ofp ⊥>0.1 GeV/c andp ⊥>0.6 GeV/c.

Multiplicity distributions of charged particles produced in the pseudorapidity range 0.9 < ηlab < 5.5 were measured in oxygen-nucleus collisions for Al, Ag, and W target nuclei at incident energies of 60 and 200 GeV per nucleon. The multiplicity differential cross sections and the pseudorapidity distributions as a function of transverse energy are presented for the various target nuclei. The correlation between charged multiplicity and transverse energy is studied as a function of transverse energy. Data are compared with predictions of the IRIS and FRITIOF generators.

We report results of the HELIOS Collaboration on low-mass dilepton and soft photon production in 450 GeV/c proton-beryllium interactions and preliminary results on sulphur tungsten collisions. Both electron and muon pairs were measured in a double spectrometer with similar kinematic acceptance for both parts. The observed dilepton yield is found to be in good agreement with the expected cumulative lepton pair production by meson decays. Based on the simultaneous direct measurements of the η, via the Dalitz decay channel, which represents the main component of the decay background, the remaining systematic errors of this experiment are as small as 20–30%. With a specially modified experimental set-up the HELIOS-3 collaboration measured low-mass muon pairs in 200 GeV/c proton-tungsten and sulfur-tungsten collisions. We show first preliminary results. For this analysis the mesonic Dalitz decay contributions are evaluated using cross-section parametrization leading to larger systematic errors. No significant additional dilepton source is detected within the framework of this preliminary analysis. Soft (pT ≤ 50 MeV/c) photon production was measured with two special independent set-ups in 450 GeV/c proton beryllium collisions. The observed production rates and spectra are well reproduced by hadronic bremsstrahlung calculations.

We have determined the double inclusive cross-section for opposite-side high-p T photons and away-side jets withθ γ ≈θ jet≈90° produced inpp collisions at the CERN Intersecting Storage Rings at $$\sqrt s = 63$$ GeV. Under the assumption that these events arise predominantly from the QCD gluon Compton process we have calculated the gluon structure function in the range 0.15≦x≦0.30 at an average square of the four-momentum transfer of 40 GeV2/c2. The data favour a soft gluon distribution in the proton.

The inclusive production of η-mesons in pp collisions at √s=63GeV and ϑCM=90° has been measured for pT<1.5GeV/c. The η/π ratio decreases from its previously measured asymptotic value of η/π ∼ 0.5 at high transverse momentum, to η/π ≈0.3 at PT = 750MeV/c and η/π ≈ 0.01 at PT=300MeV/c, in a way that consistent with phase-space considerations, e.g.mT scaling. The η/π ratio, integrated from 0.2–1.5 GeV/c, is found to be η/π=0.07±0.055.

Abstract Amorphous Ga films (a-Ga) and crystalline Ga films (α-Ga) have been irradiated at low temperatures ( The as-quench condensed amorphous phase is stable with respect to Ar irradiation, however, it transforms into the β-phase by He irradiation. The crystalline α-phase can be transformed into the amorphous state by Ar irradiation, but not by He irradiation. Rather small Ar fluences φ Since the average deposited energy was the same for the Ar and He irradiation, the different results observed for these two projectiles demonstrate the importance of the energy density within cascades for attaining a crystalline-amorphous transition by irradiation.

The production of direct photons has been measured relative to π0's in the rapidity range 2.00 < y < 2.75 in pp collisions at s = 63 GeV at the CERN Intersecting Storage Rings. The γ/π0 ratio increases from ⪅2% at pT = 1.5 GeV/c to ∼8% at pT = 4.25 GeV/c, similar to the value observed near 90°. The results indicate no strong enhancement of single-photon production due to quark bremsstrahlung in this kinematic region.

Relative yields of $\ensuremath{\varphi}$ and charged $K$ mesons are measured as functions of charged multiplicity in the central rapidity region for $\mathrm{pp}$, $\mathrm{dd}$, $p\ensuremath{\alpha}$, and $\ensuremath{\alpha}\ensuremath{\alpha}$ collisions at $\sqrt{{s}_{\mathrm{NN}}}=3.15 \mathrm{and} 44$ GeV. No anomalous strange-particle production is observed in $\ensuremath{\alpha}\ensuremath{\alpha}$ reactions relative to $\mathrm{pp}$ even at large multiplicities corresponding to events comprising less than 3.6\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}4}$ of the inclusive cross section.

We have measured the inclusive cross-section as a function of missing energy, due to the production of neutrinos or new weakly interacting neutral particles in 450 GeV/c proton-nucleus collisions, using calorimetric measurements of visible event energy. Upper limits are placed on the production of new particles as a function of their energy. These upper limits are typically an order

We have studiedpp collisions at the CERN ISR at $$\sqrt s = 63 GeV$$ using a jet trigger. We demonstrate that a sample of well-separated triple high-p T jet events can be described as due to the QCD bremsstrahlung process. The energy flow of these 3-jet events is well described by an independent fragmentation model, with a gluon-jet transverse width 33% greater than the quark-jet width. From the ratio of the 3- and 2-jet production crosssections the strong coupling is determined to lowest order in QCD. We find α s =0.18±0.03 (stat.) ±0.04 (stst.). The error does not include the theoretical uncertainty in the fragmentation scheme. We compare our results with measurements at the SPS Collider and discuss the different methods used.

We present measurements of the αα elastic scattering differential cross section at √s = 126 GeV in the range 0.05 ⩽ ‖t‖ </ 0.19 (GeV/c)2. The data give an improved definition of the first cross section minimum at ‖t‖ = 0.098 (GeV/c)2 and are consistent with theotheoretical models of nucleus-nucleus scattering. The αα total cross section obtained by extrapolation to the optical point is 280 ± 70 mb.

During the high-luminosity phase of the LHC (HL-LHC), planned to start in 2027, the accelerator is expected to deliver an instantaneous peak luminosity of up to 7.5×1034 cm−2 s−1. A total integrated luminosity of 0300 or even 0400 fb−1 is foreseen to be delivered to the general purpose detectors ATLAS and CMS over a decade, thereby increasing the discovery potential of the LHC experiments significantly. The CMS detector will undergo a major upgrade for the HL-LHC, with entirely new tracking detectors consisting of an Outer Tracker and Inner Tracker. However, the new tracking system will be exposed to a significantly higher radiation than the current tracker, requiring new radiation-hard sensors. CMS initiated an extensive irradiation and measurement campaign starting in 2009 to systematically compare the properties of different silicon materials and design choices for the Outer Tracker sensors. Several test structures and sensors were designed and implemented on 18 different combinations of wafer materials, thicknesses, and production technologies. The devices were electrically characterized before and after irradiation with neutrons, and with protons of different energies, with fluences corresponding to those expected at different radii of the CMS Outer Tracker after 0300 fb−1. The tests performed include studies with β sources, lasers, and beam scans. This paper compares the performance of different options for the HL-LHC silicon sensors with a focus on silicon bulk material and thickness.

We have studied the inclusive production of the hadrons π±, K±, p, p, Λ, Λ, ρ and ⋉ in the central region at the ISR s = 53 GeV, in both pp and pp collisions. Differences are observed only for K±, p, and p production. We then study also correlations between low-pT pp and pp pairs in the two types of collisions, separating the contribution from baryon pair production and from the incident particles (stopping protons). We observe a positive correlation between two stopping protons; between the production of two pairs, and between a stopping proton and a pair production, there are negative correlations.

Interactions of 16O and 32S at 200 GeV per nucleon in emulsion and in emulsion-tungsten chamber targets were tagged by transverse energy and multiplicity triggers in the HELIOS apparatus at CERN. As a first sample, 375 events, covering a wide range of transverse energies, were located and studied in emulsion. Results are reported in this paper. The angular distribution has been measured, event by event, with a wide pseudorapidity coverage, both in emulsion and in the HELIOS calorimeters. The total charged multiplicity and the transverse energy per charged particle have been obtained as a function of the transverse energy and of the pseudorapidity. The measured distributions are compared with the predictions of the Dual Parton Model, as coded in the IRIS generator. Assuming that 59% of the ET is transported by charged particles, and estimating the energy density by a full transparency picture, a comparison with cosmic-ray data has also been attempted.

A search is performed for the production of a massive W′ boson decaying to a top and a bottom quark. The data analysed correspond to an integrated luminosity of 19.7 fb−1 collected with the CMS detector at the LHC in proton-proton collisions at $$ \sqrt{s}=8 $$ TeV. The hadronic decay products of the top quark with high Lorentz boost from the W′ boson decay are detected as a single top flavoured jet. The use of jet substructure algorithms allows the top quark jet to be distinguished from standard model QCD background. Limits on the production cross section of a right-handed W′ boson are obtained, together with constraints on the left-handed and right-handed couplings of the W′ boson to quarks. The production of a right-handed W′ boson with a mass below 2.02 TeV decaying to a hadronic final state is excluded at 95% confidence level. This mass limit increases to 2.15 TeV when both hadronic and leptonic decays are considered, and is the most stringent lower mass limit to date in the tb decay mode.

Hadronic response and electron identification performance of the new H1 lead-scintillating fibre calorimeter are investigated in the 1 to 7 GeV energy range using data taken at the CERN Proton Synchrotron. The energy response to minimum ionizing particles and interacting pions are studied and compared to Monte Carlo simulations. The measured energy of pions interacting either in the electromagnetic or in the hadronic section is found to scale linearly with the incident energy, providing an energy resolution σE ∼ 38% within a depth of one interaction length and σE ∼ 29% for a total depth of two interaction lengths. Several electron identification estimators are studied and combined as a function of energy and impact point. The probability for pions to be misidentified as electrons of any measured energy above 1 GeV ranges from 5% (for 2 GeV incident pions) to 0.4% (at 7 GeV) for an electron detection efficiency of 90%. The probability for pions of a given energy to be misidentified as electrons of the same energy falls to 0.25% at 7 GeV.

We have studied the processpp→γγ+X at $$\sqrt s = 63 GeV$$ GeV in the central rapidity region. We report a positive signal at 96% C.L., a ratio γγ/e + e −=4.0±3.0 when the transverse momentum of each photon is above 2 GeV/c, and a cross-sectiondσ/dydM γγ=(5.5±2.7)×10−34 cm2/GeV when |y|<0.5,4<M γγ<6 GeV.

The inclusive π0 production cross-section and the η/π0 ratio have been measured inpp collisions at $$\sqrt s = 63 GeV$$ at the CERN Intersecting Storage Rings in the rapidity range 2.00<y<2.75. The π0 cross-section exhibits a strongy-dependence and falls more steeply as a function ofp T, compared with the cross-section measured aty∼0. We find a value of 0.46±0.07 for the η/π0 ratio with no significantp T dependence over the range 2.0<p T<4.0 GeV/c.

Inelastic nuclear collisions of hadrons incident on silicon sensors can generate secondary highly ionising particles (HIPs) and deposit as much energy within the sensor bulk as several hundred minimum ionising particles. The large signals generated by these ‘HIP events’ can momentarily saturate the APV25 front-end readout chip for the silicon strip tracker (SST) sub-detector of the compact muon solenoid (CMS) experiment, resulting in deadtime in the detector readout system. This paper presents studies of this phenomenon through simulation, laboratory measurements and dedicated beam tests. A proposed change to a front-end component to reduce the APV25 sensitivity to HIP events is also examined. The results are used to infer the expected effect on the performance of the CMS SST at the future large hadron collider. The induced inefficiencies are at the percent level and will have a negligible effect on the physics performance of the SST.

CYRCé is a TR24 cyclotron installed at the Institut Pluridisciplinaire Hubert Curien (IPHC) of Strasbourg operating at energies of 16–25 MeV and at intensities up to 400 μA. The accelerator is used to produce and provide radio-elements for PET and for SPECT. In 2015, IPHC started to develop a platform with the aim of performing radiobiological experiments. The PRECy platform foresees to contain three-to-five experimental stations linked to beamlines expanded from the second exit port of the cyclotron. This extension allows devoting one of the beamlines for detector studies within the framework of the CMS project. The design, the development and the commissioning of the first two beamlines are discussed in this paper.

The subsystems of the CMS silicon strip tracker were integrated and commissioned at the Tracker Integration Facility (TIF) in the period from November 2006 to July 2007. As part of the commissioning, large samples of cosmic ray data were recorded under various running conditions in the absence of a magnetic field. Cosmic rays detected by scintillation counters were used to trigger the readout of up to 15\,\% of the final silicon strip detector, and over 4.7~million events were recorded. This document describes the cosmic track reconstruction and presents results on the performance of track and hit reconstruction as from dedicated analyses.

Results from the HELIOS External Spectrometer on kaon production in 200 GeV/A S + W and p + W collisions are presented. The Kπ ratios are compared with results from a lower beam energy and are found to be remarkably similar. Evidence for secondary production of K+ by meson-baryon rescattering is reviewed. Our results at y = 1.0–1.5 are compared with neutral strange particle results at midrapidity.

In this report we describe construction and performance of two identical units of electromagnetic shower counters which were installed in the axial-field spectrometer at the CERN-ISR in 1982 to provide improved detection of photons and electrons over a 1.3 sr solid angle of the AFS calorimeter. Thallium doped sodium-iodide in the form of small blocks served as an active shower material. Vacuum photodiodes and low-noise charge sensitive electronics were used for the deposited energy measurement and signal amplification. The stable performance of the detectors over a period of more than 18 months until the closure of the ISR has proven that vacuum photodiodes can reliably be utilized in highly modularized large scale detectors operating in a high magnetic field environment.

In 2017 a new pixel detector was installed in the CMS detector. This so-called Phase-1 pixel detector features four barrel layers in the central region and three disks per end in the forward regions. The upgraded pixel detector requires an upgraded data acquisition (DAQ) system to accept a new data format and larger event sizes. A new DAQ and control system has been developed based on a combination of custom and commercial microTCA parts. Custom mezzanine cards on standard carrier cards provide a front-end driver for readout, and two types of front-end controller for configuration and the distribution of clock and trigger signals. Before the installation of the detector the DAQ system underwent a series of integration tests, including readout of the pilot pixel detector, which was constructed with prototype Phase-1 electronics and operated in CMS from 2015 to 2016, quality assurance of the CMS Phase-1 detector during its assembly, and testing with the CMS Central DAQ. This paper describes the Phase-1 pixel DAQ and control system, along with the integration tests and results. A description of the operational experience and performance in data taking is included.

Calorimeter measurements of dσdet for pp, dd, pα, and αα collisions at Snn=31.5 GeV are presented for the pseudorapidity interval |ηcm| ⩽ 0.7, extending over eight decades to Et ⩾ 30 GeV. The data are compared with models that predict nuclear cross sections directly from pp data, under the assumption of independent nucleon scatters.

A novel type of wire chamber has been constructed and first results have been obtained. The chamber has a specially constructed cathode plane, consisting of 1.5 × 2 mm2 pads in parallel rows. The pads in a row are connected resistively and every nth pad is read out. A position resolution of about 100 μm has been measured along the pad rows using charge division, with 6 mm between the readout points.

Abstract The Large Hadron Collider (LHC) at CERN will undergo major upgrades to increase the instantaneous luminosity up to 5–7.5×10 34 cm -2 s -1 . This High Luminosity upgrade of the LHC (HL-LHC) will deliver a total of 3000–4000 fb -1 of proton-proton collisions at a center-of-mass energy of 13–14 TeV. To cope with these challenging environmental conditions, the strip tracker of the CMS experiment will be upgraded using modules with two closely-spaced silicon sensors to provide information to include tracking in the Level-1 trigger selection. This paper describes the performance, in a test beam experiment, of the first prototype module based on the final version of the CMS Binary Chip front-end ASIC before and after the module was irradiated with neutrons. Results demonstrate that the prototype module satisfies the requirements, providing efficient tracking information, after being irradiated with a total fluence comparable to the one expected through the lifetime of the experiment.

The properties of high-E T events produced inpp collisions at $$\sqrt s $$ =63 GeV have been studied at the CERN Intersecting Storage Rings. The fragmentation of the jets is found to be very similar to that of jets produced ine + e − annihilation and at the SPS $$p\bar p$$ collider. We measure an excess of soft particles compared withe + e − events and this underlying event is found to be sensitive to the trigger. Thep T balance between the jets is measured. The distribution of charges in the jets indicates that a substantial fraction of the jets originate from valence quarks.

We have measured the production of one and two large transverse momentum hadrons in pp and pp interactions in the range 2 < pT < 6 GeV/c for the central rapidity region |y| < 0.9 at s = 63 and 31 GeV. No statistically significant difference between pp and pp collisions is observed. The results are in accordance with lowest order QCS perturbative calculations and rule out a large contribution of Constituent Interchange Model (CIM), di-quark of quark-fusion subprocesses in this kinematic range.

We present measurements of the rapidity and transverse-momentum distributions of the protons emitted in S+W, O+W, andp+W reactions at 200 GeV/A around the target rapidity (y=1). The rapidity density rises linearly with the transverse energy for all three systems, but the slope forp+W is much steeper than for O+W and S+W. The rapidity density forp+W is much higher than predicted by summing single nucleonnucleon collisions without any nuclear effects, indicating substantial rescattering of the produced particles. The predictions of the VENUS 3 model, including rescattering, show reasonable agreement with the data for all three systems. We do not have evidence for a strong collective flow of the outgoing particles.

We report on the production ofe ± μ∓ pairs in 450 GeV/c pBe collisions at the CERN SPS. Theeμ signal, which has average missing energy of 21 GeV, is shown to be consistent with expectations from charm decay, and implies a σ ×B for $$c\bar c$$ production in p-nucleon collisions of 0.63 ± 0.35μb. Alternatively, using an estimate of charm production from other experiments, the data imply a 95% confidence level upper limit of 1.16μb on any new physics process which producese ± μ ∓.

Abstract A system of detector modules consisting of a large size Gas Electron Multiplier (GEM), coupled to Micro Strip Gas Counters (MSGC), has been exposed to a pion beam at the Paul Scherrer Institute Cyclotron facility. As part of a CMS tracker milestone, the aim of this test was to investigate the robustness of such detectors when exposed to experimental conditions close to what is expected at the Large Hadron Collider (LHC) of CERN. Eighteen detector modules have been operated at voltage settings corresponding to 98% detection efficiency for Minimum Ionizing Particles during a period of 5 weeks. Sparking rates and strip losses have been monitored throughout the exposure. An operation margin of at least a factor of three with respect to the required gas gain has been demonstrated.

Abstract The Short Strip ASIC (SSA) is one of the four front-end chips designed for the upgrade of the CMS Outer Tracker for the High Luminosity LHC. Together with the Macro-Pixel ASIC (MPA) it will instrument modules containing a strip and a macro-pixel sensor stacked on top of each other. The SSA provides both full readout of the strip hit information when triggered, and, together with the MPA, correlated clusters called stubs from the two sensors for use by the CMS Level-1 (L1) trigger system. Results from the first prototype module consisting of a sensor and two SSA chips are presented. The prototype module has been characterized at the Fermilab Test Beam Facility using a 120 GeV proton beam.

The new lead/scintillating-fibre calorimeter (“SpaCal”) for the backward region of the H1 experiment at HERA (DESY) is equipped with fine mesh phototubes which operate in a magnetic field close to 1 T. A large sample of these tubes of the types Hamamatsu R5505 and R5506, and Hamamatsu R2490-05, have been tested in fields of up to 1.2T. We have investigated the cathode homogeneity with and without magnetic field, the gain loss under the influence of the magnetic field, and stability with time. For a subsample of tubes, we have performed additional studies on stability with respect to temperature changes, variation of gain as a function of the magnetic field, high voltage discharges, single photo-electron response, and linearity. We finally summarize the experience with these tubes after one year of operation in the experiment.

The results of two sets of transverse energy measurements, performed with incident proton beams of 200 and 450 GeV/c momentum on several nuclear targets, are presented. The transverse energy cross sections dσ/dE T are measured in a pseudorapidity range including the target fragmentation region (−0.1<η<2.9) for both data sets and also in a nearly complete pseudorapidity coverage (−0.1<η<5.5) for the data taken at 200 GeV/c incident momentum. A comparison is made of the transverse energy distributions in the target fragmentation region and in the full η region. We find that the mean value of pseudorapidity of the dE T /dη distributions shifts towards the target fragmentation region as the atomic mass number of the target increases or a selection of high transverse energy events is made. A parametrization based on a simple geometrical nucleonnucleon scattering approach was found to be inadequate to describe all features of the transverse energy distributions. Finally, the VENUS model is compared with the experimental data.

Low-transverse-momentum photon production at the CERN ISR is compared in high- and low-multiplicity events. High-transverse-energy pp collisions and low-multiplicity \ensuremath{\alpha}\ensuremath{\alpha} and pp collisions are studied. Relative photon-to-charged-track production is found to be the same in pp minimum bias, \ensuremath{\alpha}\ensuremath{\alpha} minimum bias, and pp high-transverse-energy collisions, to within 15%. No low-${P}_{T}$ excess is seen; the limits are dominated by systematic uncertainties.

In order to check the system aspects of the forward–backward MSGC tracker designed for the future CMS experiment at LHC, 38 trapezoidal MSGC counters assembled in six multi-substrates detector modules were built and exposed to a muon beam at the CERN SPS. Results on the gain uniformity along the wedge-shaped strip pattern and across the detector modules are shown together with measurements of the detection efficiency and the spatial resolution.

The electronic system developed for the SpaCal lead/scintillating-fibre calorimeters of the H1 detector in operation at the HERA ep collider is described in detail and the performance achieved during H1 data-taking is presented. The 10 MHz bunch crossing rate of HERA puts severe constraints on the requirements of the electronics. The energy and time readout are performed respectively with a 14-bit dynamic range and with a resolution of about 0.4 ns. The trigger branch consists of a nanosecond-resolution calorimetric time-of-flight for background rejection and an electron trigger based on analog `sliding windows'. The on-line background rejection currently achieved is o(10**6). The electron trigger allows a low energy trigger threshold to be set at about 0.50 +/- 0.08 (RMS) GeV with an efficiency >99.9%. The energy and time performance of the readout and trigger electronics is based on a newly-developed low noise (sigma_noise ca. 0.4 MeV) wideband (f < 200 MHz) preamplifier located at the output of the photomultipliers which are used for the fibre light readout in the ca. 1 Tesla magnetic field of H1.

A small series production of detector modules made of MicroStrip Gas Counters (MSGC) and a Gas Electron Multiplier (GEM) foil has been exposed to a high-intensity hadron beam. We report about the reproductibility and stability of the detector responses and about the occurrence and consequences of discharges in the detector. The interdependence of the four voltage differences used in the detector has been studied by simulation and with X-ray measurements. Rate dependence of the signal amplitude is observed. The behaviour of the MSGC+GEM is compared to that of a state-of-the-art MSGC. Influence of various parameters on the detector response is investigated.

The APVD is a radiation-hard integrated circuit fabricated in DMILL technology and developed for the front-end electronic to read out the tracking detectors of CMS. This paper reports test results obtained with prototypes connected to silicon and Micro-Strip Gas Chambers (MSGC) detectors in a 200GeV/c pion beam. A signal-to-noise ratio of 12 and 7, affected by residual excess noise from common mode oscillations, a spatial resolution of 7 and 11μm and a detection efficiency of 98% and 93% were measured for silicon detectors in peak and deconvolution modes, respectively. With the MSGC detector, we obtained a signal-to-noise ratio of 17 and a detection efficiency of 97%. The response of an MSGC with this electronic has also been studied with perpendicular and inclined particle tracks and good agreement with a simulation of detector and electronic was obtained.

A search for massive resonances decaying to a Z boson and a photon is performed in events with a hadronically decaying Z boson candidate, separately in light-quark and b quark decay modes, identified using jet substructure and advanced b tagging techniques. Results are based on samples of proton-proton collisions collected with the CMS detector at the LHC at center-of-mass energies of 8 and 13 TeV, corresponding to integrated luminosities of 19.7 and 2.7 inverse femtobarns, respectively. The results of the search are combined with those of a similar search in the leptonic decay modes of the Z boson, based on the same data sets. Spin-0 resonances with various widths and with masses in a range between 0.2 and 3.0 TeV are considered. No significant excess is observed either in the individual analyses or the combination. The results are presented in terms of upper limits on the production cross section of such resonances and constitute the most stringent limits to date for a wide range of masses.

The inelastic hadronic cross section in proton-lead collisions at a centre-of-mass energy per nucleon pair of 5.02 TeV is measured with the CMS detector at the LHC. The data sample, corresponding to an integrated luminosity of 12.6 +/- 0.4 inverse nanobarns, has been collected with an unbiased trigger for inclusive particle production. The cross section is obtained from the measured number of proton-lead collisions with hadronic activity produced in the pseudorapidity ranges 3<abs(eta)<5 and/or -5<abs(eta)<-3, corrected for photon-induced contributions, experimental acceptance, and other instrumental effects. The inelastic cross section is measured to be sigma[inel,pPb]=2061 +/- 3 (stat) +/- 34 (syst) +/- 72 (lum) mb. Various Monte Carlo generators, commonly used in heavy ion and cosmic ray physics, are found to reproduce the data within uncertainties. The value of sigma[inel,pPb] is compatible with that expected from the proton-proton cross section at 5.02 TeV scaled up within a simple Glauber approach to account for multiple scatterings in the lead nucleus, indicating that further net nuclear corrections are small.

Proposed in response to the ESA call for the third Medium size mission (M3), CAPSiTT is a small mission designed for a 3-year survey of the non-thermal high energy sky from an equatorial LEO orbit.With a large effective area and a very wide field of view, its single instrument, a silicon tracker, provides good imaging, spectroscopic and polarimetric capabilities with a sensitivity 10-100 times better than COMPTEL.Nucleosynthesis and particle acceleration mechanisms in various sites are the main scientific topics addressed by CAPSiTT.

A measurement of the ttbar production cross section at sqrt(s)=13 TeV is presented using proton-proton collisions, corresponding to an integrated luminosity of 2.3 inverse femtobarns, collected with the CMS detector at the LHC. Final states with one isolated charged lepton (electron or muon) and at least one jet are selected and categorized according to the accompanying jet multiplicity. From a likelihood fit to the invariant mass distribution of the isolated lepton and a jet identified as coming from the hadronization of a bottom quark, the cross section is measured to be sigma(ttbar)= 835 +/- 3 (stat) +/- 23 (syst) +/- 23 (lum) pb, in agreement with the standard model prediction. Using the expected dependence of the cross section on the pole mass of the top quark (m[t]), the value of m[t] is found to be 172.7+2.4-2.7 GeV.

Proposed in response to the ESA call for the third Medium size mission (M3), CAPSiTT is a small mission designed for a 3-year survey of the non-thermal high energy sky from an equatorial LEO orbit. With a large effective area and a very wide field of view, its single instrument, a silicon tracker, provides good imaging, spectroscopic and polarimetric capabilities with a sensitivity 10-100 times better than COMPTEL. Nucleosynthesis and particle acceleration mechanisms in various sites are the main scientific topics addressed by CAPSiTT.