F. Nessi‐Tedaldi

The analyzing power in inclusive charged pion production has been measured using the 200 GeV Fermilab polarized proton beam. A striking dependence in xF is observed in which AN increases from 0 to 0.42 with increasing xF for the π+ data and decreases from 0 to −0.38 with increasing xF for π− data. The kinematic range covered is 0.2⩽xF⩽0.9 and 0.2⩽pT⩽2.0 GeV/c. In a simple model our data indicate that at large xF the transverse spin of the proton is correlated with that of its quark constituents.

The First G-APD Cherenkov Telescope (FACT) is designed to detect cosmic gamma-rays with energies from several hundred GeV up to about 10 TeV using the Imaging Atmospheric Cherenkov Technique. In contrast to former or existing telescopes, the camera of the FACT telescope is comprised of solid-state Geiger-mode Avalanche Photodiodes (G-APD) instead of photomultiplier tubes for photo detection. It is the first full-scale device of its kind employing this new technology. The telescope is operated at the Observatorio del Roque de los Muchachos (La Palma, Canary Islands, Spain) since fall 2011. This paper describes in detail the design, construction and operation of the system, including hardware and software aspects. Technical experiences gained after one year of operation are discussed and conclusions with regard to future projects are drawn.

This report describes the physics case, the resulting detector requirements, and the evolving detector concepts for the experimental program at the Electron-Ion Collider (EIC). The EIC will be a powerful new high-luminosity facility in the United States with the capability to collide high-energy electron beams with high-energy proton and ion beams, providing access to those regions in the nucleon and nuclei where their structure is dominated by gluons. Moreover, polarized beams in the EIC will give unprecedented access to the spatial and spin structure of the proton, neutron, and light ions. The studies leading to this document were commissioned and organized by the EIC User Group with the objective of advancing the state and detail of the physics program and developing detector concepts that meet the emerging requirements in preparation for the realization of the EIC. The effort aims to provide the basis for further development of concepts for experimental equipment best suited for the science needs, including the importance of two complementary detectors and interaction regions.This report consists of three volumes. Volume I is an executive summary of our findings and developed concepts. In Volume II we describe studies of a wide range of physics measurements and the emerging requirements on detector acceptance and performance. Volume III discusses general-purpose detector concepts and the underlying technologies to meet the physics requirements. These considerations will form the basis for a world-class experimental program that aims to increase our understanding of the fundamental structure of all visible matter.

We have tested new scintillator modules with silicon photodiode readout for the upgraded Active Lead Rings (ALR) of the L3 detector at LEP II. Results are presented from data recorded in muon and electron test beams with particular emphasis on the light production and collection as a function of the particle impact position on the scintillator modules. The results from the beam test data will be used for the design of the readout and trigger electronics in conjunction with the required ALR performance as an electron tagger and beam background monitor at LEP II.

A study of events containing at least four high transverse momentum jets and a search for double parton scattering (DPS) have been performed using data collected with the UA2 detector at the CERN pp Collider (√s=630 GeV). The results are in good agreement with leading order QCD calculations. A value of σDPS<0.82 nb at 95% confidence level (CL) is obtained for the DPS cross section.

The analyzing power AN in inclusive π− and π+ production has been measured with a 200 GeV/c transversely polarized antiproton beam over a wide xF range (0.2≤xF≤0.9) and at moderate pT (0.2≤pT≤1.5GeV/c). The asymmetry AN increases with increasing xF from zero to large positive values for π−'s, and decreases from zero to large negative values for π+'s. A threshold for the onset of the asymmetry is observed about pT∼0.5GeV/c, below which AN is essentially zero and above which AN increases (decreases) with pT for π−'s ( π+'s) in the covered pT range.Received 17 April 1996DOI:https://doi.org/10.1103/PhysRevLett.77.2626©1996 American Physical Society

The two-jet invariant mass spectrum as measured in the UA2 experiment is used to search for additional heavy vector bosons decaying to two-jets. The mass of an additional W boson that couples to fermions with a V+A form is constrained to be greater than 261 GeV to the 90% confidence level. A limit on the production cross section of additional W and Z bosons is given as a function of the boson mass. A limit on the production of excited quarks is also given as a function of the excited quark mass.

The W and Z bosons masses, mw and mz, are measured using saing samples of W→ev and Z→e+e− decays observed in pp collisions at √s=630 GeV. The ration is found to be mwmz=0.8813±0.0036 ± 0.0019. This gives a value sin2 θw = 0.2234 ± 0.0064 ± 0.0033, and in combination with precise mz measurements from LEP yields mw=80.35±0.33±0.17 GeV. This result is in good agreement with other experiments, and with the standard model for a top quark mass lighter than 250 GeV.

Parity nonconservation in pp scattering has been studied by measuring the helicity dependence of the cross section, ${A}_{z}$=(${\ensuremath{\sigma}}^{+}$-${\ensuremath{\sigma}}^{\ensuremath{-}}$)/(${\ensuremath{\sigma}}^{+}$+${\ensuremath{\sigma}}^{\ensuremath{-}}$), for longitudinally polarized incident protons of 45 MeV. We found ${A}_{z}$=(-1.50\ifmmode\pm\else\textpm\fi{}0.22)\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}7}$ for the angular range 23\ifmmode^\circ\else\textdegree\fi{} to 52\ifmmode^\circ\else\textdegree\fi{} (laboratory). The uncertainty is the root square sum of the error of the measured asymmetry (\ifmmode\pm\else\textpm\fi{}0.19\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}7}$), the error of the applied corrections (\ifmmode\pm\else\textpm\fi{}0.05\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}7}$), and of various systematic errors (\ifmmode\pm\else\textpm\fi{}0.09\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}7}$). This is the most accurate result ever obtained on parity nonconservation in the nucleon-nucleon interaction.

The first prototype of a lead—liquid-argon e.m. calorimeter with accordion-shaped absorber and electrode plates has been built and tested with electron and muon beams at the CERN SPS. This novel geometry combines good granularity with high readout speed and minimal dead space. For a response peaking time of 140 ns, an energy resolution of 10%/E[GeV] and a space resolution of 4.4 mm/E[GeV] with a 2.7 cm cell size have been achieved for electrons. The position accuracy for muons is better than 2 mm.

Parity nonconservation has been studied in elastic $p\ensuremath{\alpha}$ scattering at 46 MeV with longitudinally polarized protons. The longitudinal analyzing power averaged over the range of laboratory scattering angles of roughly 30\ifmmode^\circ\else\textdegree\fi{} to 60\ifmmode^\circ\else\textdegree\fi{} is found to be ${A}_{z}=(\ensuremath{-}3.3\ifmmode\pm\else\textpm\fi{}0.9)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}7}$. This result and measurements in other light nuclear systems are used to determine weak meson-nucleon coupling constants.

The anticipated performance of calorimeter crystals in the environment expected after the planned High-Luminosity upgrade of the Large Hadron Collider (HL-LHC) at CERN has to be well understood, before informed decisions can be made on the need for detector upgrades. Throughout the years of running at the HL-LHC, the detectors will be exposed to considerable fluences of fast hadrons that have been shown to cause cumulative transparency losses in Lead Tungstate scintillating crystals. In this study, we present direct evidence of the main underlying damage mechanism. Results are shown from a test that yields a direct insight into the nature of the hadron-specific damage in Lead Tungstate calorimeter crystals exposed to 24 GeV/c protons.

The process pp→evγ+X is studied as √s=630 GeV. The observed signal is used to extract a direct measurement of the parameters κ and λ which define the magnetic dipole and electric quadrupole moments of the W boson and therefore the WWγ coupling. We find κ=1+2.6−2.2 and λ=0+1.7−1.8 and their 95% confidence limits −3.5<κ<5.9 and −3.6<λ<3.5. The results are model indepedent and in good agreement with the standard model values, κ=1 and λ=0.

Eight production quality PbWO4 crystals of CMS have been irradiated in a 20 GeV/c proton beam up to fluences of 5.4E13cm-2. The damage recovery in these crystals has been followed for over a year. Comparative irradiations with 60Co photons have been performed on seven other crystals using a dose rate of 1 kGy/h. In proton irradiated crystals the light transmission band-edge shifts and the induced absorption length is proportional to the inverse of the 4th power of the wavelength. In gamma-irradiated crystals the band-edge does not shift but formation of absorption bands is seen clearly. The absorption length induced by gamma-radiation in crystals verified to have excellent radiation hardness, saturates at a level below 0.5 m-1. In the case of protons, we observe no correlation with the pre-characterised radiation hardness of the crystals and the induced absorption increases linearly with fluence. After a fluence of 5E13 cm-2, an induced absorption length of approx. 15m-1 is seen with no sign of saturation. These observations provide strong evidence that high-energy protons create damage that cannot be reproduced with gamma-irradiation. However, these hadronic effects manifest themselves only at integral fluences well beyond 1E12cm-2 and most likely would escape undetected at lower fluences. A large fraction of the damage, both in proton- and gamma-irradiated crystals, is either stable or recovers very slowly.

The inclusive jet cross-section has been measured at the CERN pp Collider (s = 630 GeV) as a function of the jet transverse momentum (pT) and pseudorapidity (η) for pT values up to 180 GeV and for−2<η<2. The results are consistent with leading order QCD calculations, and a lower limit Λc>825 GeV (95% CL) is set on the quark compositeness scale Λc.

The large sample of W→eν events collected by the UA2 experiment at the CERN pp̄ collider between 1988 and 1990 has been used to determine the strong coupling constant αs. From a measurement of the ratio of the production rate of W events with one jet to that with no jets, αs has been extracted to second order in the MS̄ scheme: αs(M2w)=0.123±0.0.18(stat.)±0.017 (syst.).

A new polarized-proton and -antiproton beam with 185 GeV/c momentum has been built at Fermilab. The design uses the parity-nonconserving decays of lambda and antilambda hyperons to produce polarized protons and antiprotons, respectively, a beam-transport system that minimizes depolarization effects, and a set of twelve dipole magnets that rotate the beam-particle spin direction. A beam-tagging system determines the momentum and polarization of individual beam particles. This allows a selection of particles in definite intervals of momentum and polarization. Measurements performed by two different polarimeters showed that the beam is polarized and the determination of polarization by beam-particle tagging is verified. A new measurement of the analyzing power of large-xFπ0 production may lead to another beam polarimeter.

A Cerium Fluoride crystal produced during early R&D studies for calorimetry at the CERN Large Hadron Collider was exposed to a 24 GeV/c proton fluence Phi_p=(2.78 +- 0.20) x 10EE13 cm-2 and, after one year of measurements tracking its recovery, to a fluence Phi_p=(2.12 +- 0.15) x 10EE14 cm-2. Results on proton-induced damage to the crystal and its spontaneous recovery after both irradiations are presented here, along with some new, complementary data on proton-damage in Lead Tungstate. A comparison with FLUKA Monte Carlo simulation results is performed and a qualitative understanding of high-energy damage mechanism is attempted.

Axial PET is a novel geometrical concept for Positron Emission Tomography (PET), based on layers of long scintillating crystals axially aligned with the bore axis. The axial coordinate is obtained from arrays of wavelength shifting (WLS) plastic strips placed orthogonally to the crystals. This article describes the design, construction and performance evaluation of a demonstrator set-up which consists of two identical detector modules, used in coincidence. Each module comprises 48 LYSO crystals of 100 mm length and 156 WLS strips. Crystals and strips are readout by Geiger-mode Avalanche Photo Diodes (G-APDs). The signals from the two modules are processed by fully analog front-end electronics and recorded in coincidence by a VME-based data acquisition system. Measurements with point-like 22Na sources, with the modules used both individually and in coincidence mode, allowed for a complete performance evaluation up to the focal plane reconstruction of point sources. The results obtained are in good agreement with expectations and proved the set-up to be ready for the next evaluation phase with PET phantoms filled with radiotracers.

Lutetium-Yttrium Orthosilicate doped with Cerium (LYSO), as a bright scintillating crystal, is a candidate for calorimetry applications in strong ionising-radiation fields and large high-energy hadron fluences are expected at the CERN Large Hadron Collider after the planned High-Luminosity upgrade. There, proton–proton collisions will produce fast hadron fluences up to ~5×1014cm−2 in the large-rapidity regions of the calorimeters. The performance of LYSO has been investigated, after exposure to different fluences of 24 GeV c−1 protons. Measured changes in optical transmission as a function of proton fluence are presented, and the evolution over time due to spontaneous recovery at room temperature is studied. The activation of materials will also be an issue in the described environment. Studies of the ambient dose induced by LYSO and its evolution with time, in comparison with other scintillating crystals, have also been performed through measurements and FLUKA simulations.

The decays W → ev and Z → e+e− are studied in [ovbar|p]p collisions at √s=630 GeV. The products of production cross section and branching ratio are measured as σew=682±12±40 pb and σew=65.6±4.0±3.8 pb. The results are in good agreement with O(α2s) calculations of the production cross sections. Many systematic effects cancel in the ratio, R=10.4±0.70.6±0.3, which can be used to give an indirect measurement of the total width of the W boson: Γw=2.10±0.13±0.09 GeV. The width gives a limit on the top quark mass, mtop>53 GeV (95% CL), which is independent of the top decay mode.

A measurement of the inclusive cross-section for production of direct photons in p̄p collisions at a centre of mass energy of 630 GeV is presented as a function of the photon transverse momentum. The data correspond to a total integrated luminosity of 7.4 pb−1. The results support predictions from QCD theory.

Parity nonconservation in the pp interaction was studied by elastic scattering of 44.8 MeV longitudinally polarized protons. The scattering chamber consisted of a 100 bar ${\mathrm{H}}_{2}$ gas target, surrounded by a cylindrical ionization chamber in an axially symmetric arrangement, and a Faraday cup. The relative cross sections, ${\ensuremath{\sigma}}^{+}$ and ${\ensuremath{\sigma}}^{\ensuremath{-}}$, for positive and negative helicity of the incident beam, were measured by integrating the current from the Faraday cup and from the ionization chamber during 20 ms intervals, and digitizing the charges. The parity nonconserving longitudinal analyzing power ${A}_{z}=\frac{({\ensuremath{\sigma}}^{+}\ensuremath{-}{\ensuremath{\sigma}}^{\ensuremath{-}})}{({\ensuremath{\sigma}}^{+}+{\ensuremath{\sigma}}^{\ensuremath{-}})}$ was deduced from 1.4 \ifmmode\times\else\texttimes\fi{} ${10}^{6}$ individual measurements of ${p}_{z}{A}_{z}$, where ${p}_{z}\ensuremath{\simeq}0.83$ is the beam polarization. The emphasis is on quantitative treatments of instrumental effects, the most important of which is caused by the nonuniform distribution of residual transverse polarization components in the beam. The final result for the helicity dependence of the total nuclear pp cross section at a laboratory energy of 44.8 MeV is ${A}_{z}^{\mathrm{tot}}=\ensuremath{-}(2.31\ifmmode\pm\else\textpm\fi{}0.89)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}7}$. The uncertainty includes the statistical error as well as the systematic uncertainties from transverse polarization, modulation of intensity, position, emittance, and energy of the beam associated with helicity reversal, double scattering, asymmetry from $\ensuremath{\beta}$ decay, and electronic cross talk. The result is compared to theoretical predictions and to related experiments.

The single spin asymmetry for inclusive direct-photon production has been measured using a polarized proton beam of 200 GeV/c with an unpolarized proton target at −0.15 < xf < 0.15 and 2.5 < pt < 3.1 GeV/c at Fermilab. The data on the cross section for pp → γX at 2.5 < pt < 3.8 GeV/c are also provided. The measurement was done using lead-glass calorimeters and photon detectors which surrounded the fiducial area of the calorimeters. Background rejection has been done using these surrounding photon detectors. The cross section obtained is consistent with the results of previous measurements assuming a nuclear dependence of A1.0. The single spin asymmetry, AN, for the direct-photon production is consistent with zero within experimental uncertainty.

Eight PbWO4 crystals produced for the electromagnetic calorimeter of the CMS experiment at LHC have been irradiated in a 20GeV/c proton beam up to fluences of 5.4×1013p/cm2. The damage recovery in these crystals, stored in the dark at room temperature, has been followed for over a year. Comparative irradiations with 60Co photons have been performed on seven other crystals using a dose rate of 1 kGy/h. The issue whether hadrons cause a specific damage to the scintillation mechanism has been studied through light output measurements on the irradiated crystals using cosmic rays. The correlation between light output changes and light transmission changes is measured to be the same for proton-irradiated crystals and for γ-irradiated crystals. Thus, within the precision of the measurements and for the explored range of proton fluences, no additional, hadron-specific damage to the scintillation mechanism is observed.

The two-spin parameter ALL in inclusive π0 productionby longitudinally-polarized protons and antiprotons on a longitudinally-polarized proton target has been measured at the 200 GeV Fermilab spin physics facility, for π0's at xF=0 with 1⩽pt⩽3 GeV/c. The results exclude, at the 95% confidence level, values of ALL (pp) > 0.1 and < − 0.1 for π0's produced by protons, and values of ALL (pp) > 0.1 and < −0.2 for incident antiprotons. The relevance of ALL (pp) for the gluon spin density is discussed. The data are in good agreement with “conventional”, small or zero, gluon polarization.

The ${\mathrm{\ensuremath{\pi}}}^{0}$ inclusive and semi-inclusive, single-spin asymmetries have been measured using transversely polarized, 200-GeV/c proton and antiproton beams colliding with an unpolarized hydrogen target. The measured asymmetries are consistent with zero within the experimental uncertainties for the kinematic region -0.15${\mathit{x}}_{\mathit{F}}$+0.15 and 1${\mathit{p}}_{\mathit{T}}$4.5 GeV/c. Improvements in the data analysis showed that our earlier large asymmetries at ${\mathit{p}}_{\mathit{T}}$\ensuremath{\gtrsim}3 GeV/c were not correct. These data indicate that PQCD expectations seem confirmed and the higher-twist contribution to the single-spin asymmetry in ${\mathrm{\ensuremath{\pi}}}^{0}$ production at ${\mathit{x}}_{\mathit{F}}$=0 is not large. Additional evidence for such a conclusion comes from the measurement of a semi-inclusive ${\mathrm{\ensuremath{\pi}}}^{0}$ asymmetry, where associated charged particles are detected opposite to the ${\mathrm{\ensuremath{\pi}}}^{0}$ azimuthal direction. This experiment also provides high-statistics data on the inclusive ${\mathrm{\ensuremath{\pi}}}^{0}$ cross sections for pp and p\ifmmode\bar\else\textasciimacron\fi{}p collisions at \ensuremath{\surd}s\ensuremath{\approxeq}19.4 GeV. \textcopyright{} 1996 The American Physical Society.

The analyzing power AN in inclusive π0 production has been measured with use of the new 185-GeV/c Fermilab polarized proton beam. We obtain the value AN=0.10±0.03 for π0's in the kinematic region 0.2<xF<0.8 and 0.3<pT<1.2 GeV/c. In certain models of particle production this suggests that the spin of the proton is carried by its valence quarks.Received 25 July 1988DOI:https://doi.org/10.1103/PhysRevLett.61.1918©1988 American Physical Society

Surprisingly large polarizations in hyperon production by unpolarized protons have been known for a long time. The spin dynamics of the production process can be further investigated with polarized beams. Recently, a negative asymmetry ${A}_{N}$ was found in inclusive ${\ensuremath{\Lambda}}^{0}$ production with a $200\mathrm{GeV}/c$ transversely polarized proton beam. The depolarization ${D}_{\mathrm{NN}}$ in $p\ensuremath{\uparrow}+p\ensuremath{\rightarrow}{\ensuremath{\Lambda}}^{0}+X$ has been measured with the same beam over a wide ${x}_{F}$ range and at moderate ${p}_{T}$. ${D}_{\mathrm{NN}}$ reaches positive values of about 30% at high ${x}_{F}$ and ${p}_{T}\ensuremath{\sim}1.0\mathrm{GeV}/c$. This result shows a sizable spin transfer from the incident polarized proton to the outgoing ${\ensuremath{\Lambda}}^{0}$.

The analyzing power AN of proton-proton elastic scattering in the Coulomb-nuclear interference region has been measured using the 200-GeV/c Fermilab polarized proton beam. A theoretically predicted interference between the hadronic non-spin-flip amplitude and the electromagnetic spin-flip amplitude is shown for the first time to be present at high energies in the region of 1.5 × 10−3 to 5.0 × 10−2 (GeV/c)2 four-momentum transfer squared, and our results are analyzed in connection with theoretical calculations. In addition, the role of possible contributions of the hadronic spin-flip amplitude is discussed.Received 6 April 1993DOI:https://doi.org/10.1103/PhysRevD.48.3026©1993 American Physical Society

A measurement of the single-spin asymmetry AN in p↑ + p→π0 + X at 200 GeV with xF = 0 shows a transition in the production process from a “low-xT” regime with AN = 0, through an intermediate region of negative asymmetry, to a “high-xT” regime with AN > 0.3. This transition occurs at xT ≈ 0.4 and is consistent with xT-scaling of AN in pion production using polarized beams or targets from √−s=5.2 to 19.4 GeV. Results for AN in η production by polarized protons and in π0 production by polarized antiprotons are also presented.

A measurement of the cross-sections for single and double prompt photon production in pp interactions at s = 630GeV is presented. The data sample corresponds to an integrated luminosity of 13.2 pb−1. The results are in good agreement with the predictions of perturbative QCD. The signal from double prompt photon production has a statistical significance of 4.3 standard deviations.

The observation of Higgs boson production in association with a top quark-antiquark pair is reported, based on a combined analysis of proton-proton collision data at center-of-mass energies of √s = 7, 8, and 13 TeV, corresponding to integrated luminosities of up to 5.1, 19.7, and 35.9  fb^(-1), respectively. The data were collected with the CMS detector at the CERN LHC. The results of statistically independent searches for Higgs bosons produced in conjunction with a top quark-antiquark pair and decaying to pairs of W bosons, Z bosons, photons, τ leptons, or bottom quark jets are combined to maximize sensitivity. An excess of events is observed, with a significance of 5.2 standard deviations, over the expectation from the background-only hypothesis. The corresponding expected significance from the standard model for a Higgs boson mass of 125.09 GeV is 4.2 standard deviations. The combined best fit signal strength normalized to the standard model prediction is 1.26^(+0.31)_(−0.26).

The considerable polarization of hyperons produced at high xF has been known for a long time and has been interpreted with various theoretical models in terms of the constituents' spin. Recently, the analyzing power in inclusive Λ0 hyperon production has also been measured using the 200GeV/c Fermilab polarized proton beam. The covered kinematic range is 0.2≤xF≤1.0 and 0.1≤pT≤1.5GeV/c. The data indicate a negative asymmetry at large xF and moderate pT. These results can further test the current ideas on the underlying mechanisms for hyperon polarization.Received 5 December 1994DOI:https://doi.org/10.1103/PhysRevLett.75.3073©1995 American Physical Society

The Brookhaven Alternating Gradient Synchrotron polarized proton beam incident on a beryllium target was used for inclusive \ensuremath{\Lambda} production at beam momenta of 13.3 and 18.5 GeV/c. The beam polarization was transverse to the beam direction with magnitude 0.63 at 13.3 GeV/c and 0.40 at 18.5 GeV/c. The \ensuremath{\Lambda} polarization was measured and found to be in agreement with results from earlier experiments which used unpolarized proton beams. Analyzing power ${A}_{N}$ and spin transfer ${D}_{\mathrm{NN}}$ of the \ensuremath{\Lambda}'s were both measured and compared with a hyperon-polarization model in which the polarization arises from a Thomas-precession effect. There is good agreement with its predictions: ${A}_{N}$=0 and ${D}_{\mathrm{NN}}$=0. In particular, our measurement of 〈${D}_{\mathrm{NN}}$〉=-0.009\ifmmode\pm\else\textpm\fi{}0.015 supports the idea that the valence quarks carry all of the hadron spin, since this assumption is implicit in the model's use of SU(6) wave functions to form final-state hadrons from beam fragments and sea quarks. The presence of substantial ${K}_{S}$ samples at both beam momenta and \ensuremath{\Lambda}\ifmmode\bar\else\textasciimacron\fi{}'s at 18.5 GeV/c prompted a measurement of their analyzing powers, which yielded ${A}_{N}$(${K}_{S}$)=-0.094\ifmmode\pm\else\textpm\fi{}0.012 at 13.3 GeV/c beam momentum and -0.076\ifmmode\pm\else\textpm\fi{}0.015 at 18.5 GeV/c, and ${A}_{N}$(\ensuremath{\Lambda}\ifmmode\bar\else\textasciimacron\fi{})=0.03\ifmmode\pm\else\textpm\fi{}0.10.

A PbWO4 crystal produced for the electromagnetic calorimeter of the CMS experiment at the LHC was cut into three equal-length sections. The central one was irradiated with 290MeV/c positive pions up to a fluence of (5.67±0.46)×1013cm-2, while the other two were exposed to a 24GeV/c proton fluence of (1.17±0.11)×1013cm-2. The damage recovery in these crystals, stored in the dark at room temperature, has been followed over two years. The comparison of the radiation-induced changes in light transmission for these crystals shows that damage is proportional to the star densities produced by the irradiation.

The invariant double-differential cross section, E1E2d6σ / dp31dp32, and the double-spin asymmetry, A LL, for inclusive multi-γ pair production in which γ-rays came from neutral mesons were measured with a 200 GeV/c longitudinally-polarized proton beam and a longitudinally-polarized proton target. Most of the multi-γ pairs comes from two-jet type events which are sensitive to partonic interaction. The ALL values were found to be consistent with zero. The invariant double-differential cross section for inclusive π0π0 production was also measured. These measured cross sections are consistent with LUND Monte Carlo simulations. Using the LUND Monte Carlo simulation package with the Carlitz-Kaur model of spin dependent distribution functions of valence quarks, the ALL values have been compared with theoretical predictions of gluon polarization, ΔG/G. The results put restrictions on the size of ΔG/G in the region of 0.05 ⪅ x ⪅ 0.35.

A prototype lead-liquid-argon electromagnetic calorimeter with parallel plates and Accordion geometry has been equipped with high speed readout electronics and tested with electron and muon beams at the CERN SPS. For a response peaking time of about 35 ns, fast enough for operation at the future hadron colliders, the energy resolution for electrons is 9.6%/√E[GeV] with a local constant term of 0.3% and a noise contribution of 0.33E[GeV]. The spatial accuracy achieved with a detector granularity of 2.7 cm is 3.7mmE[GeV] and the angular resolution 12 mrad at 60 GeV.

Parity nonconservation in the hadronic interaction was studied by elastic scattering of 46 MeV longitudinally polarized protons on $^{4}\mathrm{He}$. The scattering chamber consisted of a 110 bar helium gas target, surrounded by a cylindrical ionization chamber in an axially symmetric arrangement, and a Faraday cup. The relative cross sections, ${\ensuremath{\sigma}}^{+}$ and ${\ensuremath{\sigma}}^{\mathrm{\ensuremath{-}}}$, for positive and negative helicity of the incident beam were measured by integrating the currents from the Faraday cup and from the ionization chamber during 20 ms intervals, and digitizing the charges. The angular acceptance function of the ionization chamber extends from ${\mathrm{theta}}_{\mathrm{lab}=31}$\ifmmode^\circ\else\textdegree\fi{} to approximately 80\ifmmode^\circ\else\textdegree\fi{}, with maximum weight at 41\ifmmode^\circ\else\textdegree\fi{}. The parity nonconserving longitudinal analyzing power ${A}_{z}$=(${\ensuremath{\sigma}}^{+}$-${\ensuremath{\sigma}}^{\mathrm{\ensuremath{-}}}$)/(${\ensuremath{\sigma}}^{+}$+\ensuremath{\sigma} $^{\mathrm{\ensuremath{-}}}$) was deduced from 2.3\ifmmode\times\else\texttimes\fi{}${10}^{6}$ individual measurements of ${p}_{z}$${A}_{z}$. The magnitude of the beam polarization was \ensuremath{\Vert}${p}_{z}$\ensuremath{\Vert}\ensuremath{\simeq}0.83. The emphasis is on quantitative treatments of instrumental effects, the most important of which is caused by the nonuniform distribution of residual transverse polarization components of the beam. The final result for the longitudinal analyzing power at a mean laboratory energy of 46 MeV is ${A}_{z}$=-(3.3\ifmmode\pm\else\textpm\fi{}0.9)\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}7}$. The uncertainty includes the statistical error as well as the systematic uncertainties from transverse polarization, modulation of intensity, position, emittance, and energy of the beam associated with helicity reversal, double scattering, asymmetry from \ensuremath{\beta} decay, and electronic cross talk. The result is compared to theoretical predictions and to related experiments.

We describe the concept and first experimental tests of a novel 3D axial Positron Emission Tomography (PET) geometry. It allows for a new way of measuring the interaction point in the detector with very high precision. It is based on a matrix of long Lutetium-Yttrium OxyorthoSilicate (LYSO) crystals oriented in the axial direction, each coupled to one Geiger Mode Avalanche Photodiode (G-APD) array. To derive the axial coordinate, Wave Length Shifter (WLS) strips are mounted orthogonally and interleaved between the crystals. The light from the WLS strips is read by custom-made G-APDs. The weighted mean of the signals in the WLS strips has proven to give very precise axial resolution. The achievable resolution along the three axes is mainly driven by the dimensions of the LYSO crystals and WLS strips. This concept is inherently free of parallax errors. Furthermore, it will allow identification of Compton interactions in the detector and for reconstruction of a fraction of them, which is expected to enhance image quality and sensitivity. We present the results of proof-of-principle tests and qualification measurements of the various components prepared to build a larger scale demonstrator consisting of two matrices of 8×6 LYSO crystals and 312 WLS strips.

Further tests of lead tungstate crystal matrices made in high-energy electron beams in 1996, using new crystals, new APDs and an improved test setup confirm that an energy resolution of better than 0.6% at 100 GeV can be obtained when the longitudinal uniformity of the struck crystal is adequate. Light loss measurements under low dose irradiation are reported. It is shown that there is no loss of energy resolution after irradiation and it is demonstrated that the calibration change due to light loss can be tracked with a precision monitoring system. Successful tests with a preshower device, equipped with a silicon strip detector readout, are also described.

The process t→H+b, H+→τ+v, τ+→hadrons+v and its charge conjugate are investigated by seeking an excess in number of observed τ's beyond that expected from the standard model under the assumption of e-τ universality. No such excess is found and new regions of the mH−mt plane are excluded for B(H+→τv) = 0.5 and 1.0. In addition, the ratio of couplings of the τ and e to the W is precisely measured as gwτ/gwe = 1.02 ± 0.04(stat.)±0.04(syst.).

We have measured the polarization of \ensuremath{\Lambda}'s inclusively produced by the polarized proton beam at the Brookhaven Alternating Gradient Synchrotron at 13.3 and 18.5 GeV/c. Data were taken in the central and beam-fragmentation region with hyperon transverse momenta from 0.4 to 2.5 GeV/c. The \ensuremath{\Lambda} polarization parameter P is found to be large in agreement with earlier data at other energies. The analyzing power ${A}_{N}$ and spin transfer ${D}_{\mathrm{NN}}$ are nearly zero in the same kinematic region, as predicted by certain models of particle production.

A novel geometry for a sampling calorimeter employing inorganic scintillators as an active medium is presented. To overcome the mechanical challenges of construction, an innovative light collection geometry has been pioneered, that minimises the complexity of construction. First test results are presented, demonstrating a successful signal extraction. The geometry consists of a sampling calorimeter with passive absorber layers interleaved with layers of an active medium made of inorganic scintillating crystals. Wavelength-shifting (WLS) fibres run along the four long, chamfered edges of the stack, transporting the light to photodetectors at the rear. To maximise the amount of scintillation light reaching the WLS fibres, the scintillator chamfers are depolished. It is shown herein that this concept is working for cerium fluoride (CeF3) as a scintillator. Coupled to it, several different types of materials have been tested as WLS medium. In particular, materials that might be sufficiently resistant to the High- Luminosity Large Hadron Collider radiation environment, such as cerium-doped Lutetium- Yttrium Orthosilicate (LYSO) and cerium-doped quartz, are compared to conventional plastic WLS fibres. Finally, an outlook is presented on the possible optimisation of the different components, and the construction and commissioning of a full calorimeter cell prototype is presented.

We report on measurements of mass and total decay width of the W boson and of triple-gauge-boson couplings, γWW and ZWW, with the L3 detector at LEP. W-pair events produced in e+e− interactions between 161 GeV and 172GeV centre-of-mass energy are selected in a data sample corresponding to a total luminosity of 21.2 pb−1. The mass and total decay width of the W boson are determined to be MW = 80.75−0.27+0.26(exp.) ± 0.03 (LEP) GeV and ΓW = 1.74−0.78+0.88(stat.) ± 0.25(syst.)GeV, respectively. Limits on anomalous triple-gauge-boson couplings, γWW and ZWW, are determined, in particular −1.5 < δZ < 1.9 (95% CL), excluding vanishing ZWW coupling at more than 95% confidence level.

A measurement method is described which allows to accurately track the scintillation light yield changes of lead tungstate crystals. The method has been used to study crystals to which post-growth high-temperature annealing treatments in various atmospheres were applied; it has allowed to select the most radiation resistant crystals and thus to optimize the annealing process. We describe the irradiation facility, irradiation procedure and results obtained. This work has led to the production of radiation resistant 50 mm long crystals and the process is now being extended to 230 mm long crystals.

The highest-energy measurement of ΔσL(pp) and the first ever measurement of ΔσL(p¯p), the differences between proton-proton and antiproton-proton total cross sections for pure longitudinal spin states, are described. Data were taken using 200-GeV/c polarized beams incident on a polarized-proton target. The results are measured to be ΔσL(pp)=−42±48(stat)±53(syst) μb and ΔσL(p¯p)=−256±124(stat)±109(syst) μb. Many tests of systematic effects were investigated and are described, and a comparison to theoretical predictions is also given. Measurements of parity nonconservation at 200 GeV/c in proton scattering and the first ever of antiproton scattering have also been derived from these data. The values are consistent with zero at the 10−5 level. Received 3 May 1996DOI:https://doi.org/10.1103/PhysRevD.55.1159©1997 American Physical Society

A description is given of a TPC system that operates in a relativistic heavy-ion beam and yields good track reconstruction efficiency in very-high-multiplicity events. The mechanical construction of the chamber is discussed. A set of custom hybrid circuits are used to build a very compact, cost-effective electronics system mounted directly on the chamber. Results from running in test beams and from preliminary experimental runs are given.

We have measured the analyzing power in π+, π−, and KS0 production by a polarized proton beam at 13.3 and 18.5 GeV/c. The data cover the central and the beam fragmentation region, in the transverse-momentum range up to 2 GeV/c. The results indicate that sizable effects are present at high xF and also persist into the hard-scattering region for KS0 and π+. A zero value of the analyzing power was observed for π− production.Received 3 August 1989DOI:https://doi.org/10.1103/PhysRevD.41.13©1990 American Physical Society

A search has been made for scalar leptoquark pair production with the upgraded UA2 detector at the CERN pp Collider at √s = 630 GeV, investigating decays of the leptoquark into a quark and either an electron or an electron neutrino. From an event sample corresponding to an integrated luminosity of 13 pb−1 a lower limit has been determined for the mass of first generation leptoquarks, yielding 67 GeV (95% CL) for a scalar leptoquark decaying with a 50% branching ratio into a quark and an electron.

The analyzing power (spin-dependent azimuthal asymmetry) has been observed for the first time in the nuclear Coulomb coherent production process, the ``Primakoff process,'' with the use of the newly constructed 185-GeV/c Fermilab polarized proton beam. We have observed a large asymmetry of this process in the regions of \ensuremath{\Vert}t'\ensuremath{\Vert}0.001 (GeV/c${)}^{2}$ and 1.36(${\ensuremath{\pi}}^{0}$p)1.52 GeV/${c}^{2}$, where the Coulomb process is predominant. The measured asymmetry is consistent with the analyzing power of the existing low-energy \ensuremath{\gamma}+p\ensuremath{\rightarrow}${\ensuremath{\pi}}^{0}$+p data.

The analyzing power AN of proton-proton, proton-hydrocarbon, and antiproton-hydrocarbon, scattering in the Coulomb-nuclear interference region has been measured using thhe 185 GeV/c Fermilab polarized-proton and -antiproton beams. The results are found to be consistent with theoretical predictions within statistical uncertainties.

We have measured the polarization P, the analyzing power A, and the polarization transfer D of ${\ensuremath{\Sigma}}^{0}$'s produced inclusively by a polarized proton beam at 18.5 GeV/c. Our data cover a region of moderate ${p}_{T}$ (average 1 GeV/c) and Feynman x up to 0.75. We find agreement with a previous measurement of the ${\ensuremath{\Sigma}}^{0}$ polarization P. We observe nonzero values for A and D, but they are significantly smaller than predictions based on a simple parton-recombination model. We have extended this model to include finite transversity spin flips, which improves agreement with the data considerably.

Using matrices of lead tungstate crystals, energy resolutions better than 0.6% at 100 GeV have been achieved in the test beam in 1995. It has been demonstrated that a lead tungstate electromagnetic calorimeter read out by avalanche photodiodes can consistently achieve the excellent energy resolutions necessary to justify its construction in the CMS detector. The performance achieved has been understood in terms of the properties of the crystals and photodetectors.

Abstract We present the results of a measurement of neutral V production with 14.6 × A GeV/ c Si beams on Au and Cu targets. The Λ and K s 0 yields were measured as a function of negative particle multiplicity. Effective temperatures were determined from an exponential fit to the transverse mass distributions.

The design and construction of a PET camera module with high sensitivity, full 3-D spatial reconstruction and very good energy resolution is presented. The basic principle consists of an axial arrangement of long scintillation crystals around the Field Of View (FOV), providing a measurement of the transverse coordinates of the interacting 511 keV gamma ray. On top of each layer of crystals, an array of Wave-Length Shifter (WLS) strips, which collect the light leaving the crystals sideways, is positioned orthogonal to the crystal direction. The signals in the WLS strips allow a precise measurement of the z (axial) co-ordinate of the 511 keV γ-ray gamma impact. The construction of two modules used for demonstration of the concept is described. First preliminary results on spatial and energy resolution from one full module will be shown.

Abstract Standard Positron Emission Tomography (PET) cameras need to reach a compromise between spatial resolution and sensitivity. To overcome this limitation we developed a novel concept of PET. Our AX-PET demonstrator is made of LYSO crystals aligned along the z coordinate (patient's axis) and WLS strips orthogonally placed with respect to the crystals. This concept offers full 3D localization of the photon interaction inside the camera. Thus the spatial resolution and the sensitivity can be simultaneously improved and the reconstruction of Compton interactions inside the detector is also possible. Moreover, by means of G-APDs for reading out the photons, both from LYSO and WLS, the detector is insensitive to magnetic fields and it is then suitable to be used in a combined PET/MRI apparatus. A complete Monte Carlo simulation and dedicated reconstruction software have been developed. The two final modules, each composed of 48 crystals and 156 WLS strips, have been built and fully characterized in a dedicated test set-up. The results, obtained with a 22 Na point source (0.25 mm diameter), of the single module performances and a first estimation of the performances with the two module system are reported.

While the CMS experiment is currently harvesting LHC collision data at CERN, the performance of its electromagnetic calorimeter (ECAL) is being constantly monitored, and work has started to assess the need for changes to the detector to ensure an adequate performance for High-Luminosity LHC (HL-LHC) running, which is planned for 2022 and beyond. In this paper, results from CMS running, beam tests and laboratory measurements are combined to anticipate the detector performance evolution at the HL-LHC. Further, various R&D studies are illustrated, that will provide a useful choice for electromagnetic calorimetry at the HL-LHC.

A measurement of the gluon structure fusion using direct photon events observed with the UA2 detector in pp collisions at √s=630 GeV is presented. The x-range covered by this analysis is between 0.049 and 0.207 and the Q2 range is between 280 GeV2 and 3670 GeV2. The data sample corresponds to an integrated luminosity of 7.14 pb−1. The results are found to be in good agreement with the gluon distributions measured in deep inelastic scattering experiments extrapolated to the UA2 Q2 values.

Following the observation of an excess of single photoelectrons in the scintillation spectrum of some lead tungstate crystals after irradiation, a method has been developed and applied to crystals grown under various conditions to determine whether scintillating lead tungstate crystals also respond to γ irradiation with long-term afterglow, in the minutes to hours range.

Crystals are used as a homogeneous calorimetric medium in many high-energy physics experiments. For some experiments, performance has to be ensured in very difficult operating conditions, like a high radiation environment, very large particle fluxes, high collision rates, placing constraints on response and readout time. An overview is presented of recent achievements in the field, with particular attention given to the performance of Lead Tungstate (PWO) crystals exposed to high particle fluxes.

The First G-APD Cherenkov telescope (FACT) is the first telescope using silicon photon detectors (G-APD aka. SiPM). It is built on the mount of the HEGRA CT3 telescope, still located at the Observatorio del Roque de los Muchachos, and it is successfully in operation since Oct. 2011. The use of Silicon devices promises a higher photon detection efficiency, more robustness and higher precision than photo-multiplier tubes. The FACT collaboration is investigating with which precision these devices can be operated on the long-term. Currently, the telescope is successfully operated from remote and robotic operation is under development. During the past months of operation, the foreseen monitoring program of the brightest known TeV blazars has been carried out, and first physics results have been obtained including a strong flare of Mrk501. An instantaneous flare alert system is already in a testing phase. This presentation will give an overview of the project and summarize its goals, status and first results.

A sampling calorimeter using cerium fluoride scintillating crystals as active material, interleaved with heavy absorber plates, and read out by wavelength-shifting (WLS) fibers is being studied as a calorimeter option for detectors at the upgraded High-Luminosity LHC (HL-LHC) collider at CERN. A prototype has been exposed to electron beams of different energies at the INFN Frascati (Italy) Beam Test Facility. This paper presents results from the studies performed on the prototype, such as signal amplitudes, light yield and energy resolution.

Since two years, the FACT telescope is operating on the Canary Island of La Palma. Apart from its purpose to serve as a monitoring facility for the brightest TeV blazars, it was built as a major step to establish solid state photon counters as detectors in Cherenkov astronomy. The camera of the First G-APD Cherenkov Telesope comprises 1440 Geiger-mode avalanche photo diodes (G-APD), equipped with solid light guides to increase the effective light collection area of each sensor. Since no sense-line is available, a special challenge is to keep the applied voltage stable although the current drawn by the G-APD depends on the flux of night-sky background photons significantly varying with ambient light conditions. Methods have been developed to keep the temperature and voltage dependent response of the G-APDs stable during operation. As a cross-check, dark count spectra with high statistics have been taken under different environmental conditions. In this presentation, the project, the developed methods and the experience from two years of operation of the first G-APD based camera in Cherenkov astronomy under changing environmental conditions will be presented.

We describe our R&D effort to develop radiation-hard scintillating and wavelength shifting fibers by doping fused-silica with cerium. This new type of cerium-doped fiber potentially offers myriad new applications in calorimeters for high-energy physics, tracking systems, and profiling of charged particle beams.

The status is given of the lead tungstate (PbWO4) electromagnetic crystal calorimeter for the CMS detector at LHC. This includes the progress on the engineering design of the calorimeter and its readout system, latest results on PbWO4 crystals and photodetector development, with particular attention to radiation hardness issues, and results from test measurements in particle beams.

Scintillating ceramics are a promising, new development for various applications in science and industry. Their application in calorimetry for particle physics experiments is expected to involve an exposure to high levels of ionizing radiation. In this paper, changes in performance have been measured for scintillating ceramic samples of different composition after exposure to penetrating ionizing radiation up to a dose of 38 kGy.

Studies have been done and continue on the design and construction of a Shashlik detector using Radiation hard quartz capillaries filled with wavelength shifting liquid to collect the scintillation light from LYSO crystals for use as a calorimeter in the Phase II CMS upgrade at CERN. The work presented here focuses on the studies of the capillaries and liquids that would best suit the purpose of the detector. Comparisons are made of various liquids, concentrations, and capillary construction techniques will be discussed.

A cerium fluoride matrix composed of nine longitudinally segmented towers, approximately 25X0 long, has been tested in electron, muon and pion beams of momenta ranging from 10 to 150 GeV/c. The results are discussed in terms of light yield, electronic noise, energy and position resolution. In spite of serious imperfections in geometry and quality of some of the crystals, an electron energy resolution of ∼0.5% has been obtained with a silicon photodiode readout, for energies above 50 GeV. The performance of cerium fluoride in a beam, its high density, high light yield and fast response, radiation resistance and ruggedness make it a very good candidate for high-resolution calorimetry at future colliders. The best conditions for production of large high-quality crystals are being studied in several firms over the world. Many CeF3 crystals, 2 × 2 cm2 or 3 × 3 cm2 in cross section and up to 28 cm long, were received in 1994 from four companies, some of them with excellent light yield and radiation hardness.

A prototype liquid argon preshower detector with a strip granularity of 2.5 mm has been tested at the CERN SPS in front of a liquid argon Accordion calorimeter. For charged tracks a signal-to-noise ratio of 9.4 and a space resolution of 340 μm were measured; the rejection power against overlapping photons produced in the decay of 50 GeV π0's is larger than 3; the precision on

Abstract A prototype of a lead liquid argon accordion calorimeter with two types of cylindrical geometry was constructed and equipped with high speed readout electronics. The energy resolution for electrons is 10%/√E (GeV) with a local constant term of 0.65%. The resolutions obtained for position and angular measurements are given.

Scintillating crystals are used for calorimetry in several high-energy physics experiments. For some of them, performance has to be ensured in difficult operating conditions, like a high radiation environment, very large particle fluxes and high collision rates. Results are presented here from a thorough series of measurements concerning mainly the effect of charged hadrons on lead tungstate. It is also shown how these results can be used to predict the effect on crystals due to a given flux of particles.

The Axial PET (AX-PET) concept proposes a novel detection geometry for PET, based on layers of long scintillating crystals axially aligned with the bore axis. Arrays of wavelength shifting (WLS) strips are placed orthogonally and underneath the crystal layers; both crystals and strips are individually readout by G-APDs. The axial coordinate is obtained from the WLS signals by means of a Center-of-Gravity method combined with a cluster algorithm. This design allows spatial resolution and sensitivity to be decoupled and thus simultaneously optimized. In this work we present the latest results obtained with the 2-module AX-PET scanner prototype, which consists of 6 radial layers of 8 LYSO crystals each (crystal size: 3 × 3 × 100 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> ). The WLS arrays comprise 26 strips (3-mm wide) per layer. The estimated energy resolution from point-like measurements is 11.8% (FWHM at 511 keV). The intrinsic spatial resolution was measured for the two modules in coincidence at two different configurations using point-like sources, showing very little degradation when the modules were placed oblique to each other. The axial spatial resolution was 1.5 mm (FWHM) in all the studied cases. Tomographic data of extended phantoms filled with fluorine-18 have been acquired. Imaging a larger transaxial Field-of-View (when compared to the previous measurement campaign) was possible thanks to implementing secondary motion of one of the modules. We have also developed various reconstruction approaches which take into account the particular nature of AX-PET data, as well as a count rate model which allowed us to develop an acquisition protocol able to compensate for count losses. The reconstructed phantom images confirm the imaging capabilities of AX-PET, and the recent advancements in the DAQ let us expect significant improvements for future campaigns.

A prototype for a sampling calorimeter made out of cerium fluoride crystals interleaved with tungsten plates, and read out by wavelength-shifting fibres, has been exposed to beams of electrons with energies between 20 and 150 GeV, produced by the CERN Super Proton Synchrotron accelerator complex. The performance of the prototype is presented and compared to that of a Geant4 simulation of the apparatus. Particular emphasis is given to the response uniformity across the channel front face, and to the prototype׳s energy resolution.

Calculations of parity non-conserving (PNC) amplitudes are presented and used to analyze a measurement of the longitudinal analyzing power Az in 45 MeV p-p scattering. For the PNC interaction the usual parametrization in terms of one meson exchanges is used while the strong scattering states are obtained from the Paris potential and, for comparison, also from the Reid soft core potential. The dependence on weak and strong parameters is exhibited.

Geiger-mode avalanche photodiodes (G-APD, SiPM) are a much discussed alternative to photomultiplier tubes in Cherenkov astronomy. The First G-APD Cherenkov Telescope (FACT) collaboration builds a camera based on a hexagonal array of 1440 G-APDs and has now finalized its construction phase. A light-collecting solid PMMA cone is glued to each G-APD to eliminate dead space between the G-APDs by increasing the active area, and to restrict the light collection angle of the sensor to the reflector area in order to reduce the amount of background light. The processing of the signals is integrated in the camera and includes the digitization using the domino ring sampling chip DRS4.

The ratio of branching fractions of theW decaying to τ ande leptons is measured using $$\bar pp$$ collisions at $$\sqrt s = 630$$ GeV. The ratio of the electroweak charged current couplings to theW is then determined to beg /g =0.997±0.056 (stat.)±0.042 (syst.). The decay modeZ→τ+→τ+ is observed and also found to be consistent withe-τ universality.

We describe a PET device based on a novel method to extract the coordinates of the interaction point of the 511keV γ rays from 100 mm long and thin LYSO (Lutetium Yttrium OxyorthoSilicate) scintillator bars, positioned axially in the tomograph. The coordinate along the hit crystal is measured by using a hodoscope of Wave Length Shifting (WLS) plastic strips mounted perpendicularly to each plane of scintillators. As photodetectors, new Geiger mode Avalanche PhotoDetectors (G-APDs) with integrated electronics are being used to detect both the hit crystal in a block (x and y coordinates) and the interaction point in the crystal (z coordinate) through the light escaping from the crystal and transmitted to the WLS strips. In this way, the γ interaction point can be determined with a spatial resolution of few cubic millimeters down to a minimum deposited energy of about 50 keV, resulting in a volumetric precision very close to the limits imposed by the physics of the positron annihilation. The method allows to increase the detection efficiency without affecting the spatial resolution by adding scintillator planes in the radial direction. A demonstrator scanner, based on two matrices of 8 × 6 LYS crystals and 312 WLS strips, slotted in between the crystals, is under construction. Preliminary results from the feasibility studies of the various components will be presented.

The AX-PET is a new geometrical concept for a high resolution 3D PET scanner, based on matrices of axially oriented LYSO crystals interleaved by stacks of WLS, both individually read out by G-APDs. A PET demonstrator, based on two detector modules used in coincidence, is currently under construction.

We have evaluated the performance of a Ce-doped fused-silica fiber as wavelength shifter coupled to a CeF3 crystal using electron beams at CERN . The pulse shape and collection efficiency were measured using irradiated (100 kGy) and un-irradiated fibers. In addition, we evaluated the light yield of various Ce-doped fibers and explored the possibility of using them in the future, including for precision timing applications in a high-luminosity collider environment.

In PET imaging, improving sensitivity while maintaining very good spatial resolution is crucial. To achieve this goal, we propose a novel concept of PET scanner, with axially arranged crystals, providing a high sensitivity and a 3D reconstruction of the gamma interaction point. The trans-axial coordinate is given by the crystal hit, while the z coordinate is reconstructed by the weighted distribution of light escaping the crystal and entering into an array of Wave Length Shifting (WLS) strips interleaving the crystal layers. This novel configuration allows full identification of Compton interactions in the crystals that can be included in image reconstruction thus enhancing the sensitivity. We present preliminary results obtained by a small prototype consisting of 4×4 crystals with orthogonally interleaved WLS strips. Experimental data are compared to simulated data.

A TPC (time projection chamber) detector system has been developed to function in the very-high-multiplicity environment of relativistic-heavy-ion experiments. A TPC was chosen because it directly gives three-dimensional points on the tracks, which is a very significant help for track-finding. Of prime importance is a combination of high efficiency, low noise, and two track resolution capability. A significant development is a system of hybridized, high-sensitivity, on-chamber digitizing electronics. A description of the TPC modules, the digitizing electronics, and test results is given.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A sampling calorimeter using cerium fluoride scintillating crystals as active material, interleaved with absorber plates made of tungsten, and read out by wavelength-shifting fibres has been tested with high-energy electron beams at the CERN SPS H4 beam line, as well as with lower-energy beams at the INFN Frascati Beam Test Facility in Italy. Energy resolution studies revealed a low stochastic term (<10%/E). This result, combined with high radiation hardness of the material used, marks this sampling calorimeter as a good candidate for the detectors׳ forward regions during the high luminosity phase of LHC.

The First G-APD Cherenkov Telescope (FACT) became operational at La Palma in October 2011. Since summer 2012, due to very smooth and stable operation, it is the first telescope of its kind that is routinely operated from remote, without the need for a data-taking crew on site. In addition, many standard tasks of operation are executed automatically without the need for manual interaction. Based on the experience gained so far, some alterations to improve the safety of the system are under development to allow robotic operation in the future. We present the setup and precautions used to implement remote operations and the experience gained so far, as well as the work towards robotic operation.

The High-Luminosity phase of the Large Hadron Collider at CERN (HL-LHC) poses stringent requirements on calorimeter performance in terms of resolution, pileup resilience and radiation hardness. A tungsten-CeF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> sampling calorimeter is a possible option for the upgrade of current detectors. A prototype, read out with different types of wavelength-shifting fibers, has been built and exposed to high energy electrons, representative for the particle energy spectrum at HL-LHC, at the CERN SPS H4 beam line. This paper shows the performance of the prototype, mainly focussing on energy resolution and uniformity. A detailed simulation has been also developed in order to compare with data and to extrapolate to different configurations to be tested in future beam tests. Additional studies on the calorimeter and the R&D projects ongoing on the various components of the experimental setup will be also discussed.

Results on the cross section for the production of electron pairs in pp collisions at √s = 630 GeV are presented. The measured value is σ = 405 ± 51 (syst.) ± 84 (syst.) pb, in the invariant mass interval 10 < m< 70 GeV. The results are compared to recent theoretical calculations which include O(αs2) QCD contributions. The comparison of these data with those of lower energy experiments show approximate scaling as a function of the variable √τ =m√s.

Within the FACT project, we construct a new type of camera based on Geiger-mode avalanche photodiodes (G-APDs). Compared to photomultipliers, G-APDs are more robust, need a lower operation voltage and have the potential of higher photon-detection efficiency and lower cost, but were never fully tested in the harsh environments of Cherenkov telescopes. The FACT camera consists of 1440 G-APD pixels and readout channels, based on the DRS4 (Domino Ring Sampler) analog pipeline chip and commercial Ethernet components. Preamplifiers, trigger system, digitization, slow control and power converters are integrated into the camera.

AX-PET is a novel PET concept based on long crystals axially arranged and orthogonal Wavelength shifter (WLS) strips, both individually readout by Geiger-mode Avalanche Photo Diodes (G-APD). Its design was conceived in order to reduce the parallax error and simultaneously improve spatial resolution and sensitivity. The assessment of the AX-PET concept and potential was carried out through a set of measurements comprising individual module characterizations and scans in coincidence mode of point-like and extended sources. The estimated energy and spatial resolutions from point-like measurements are R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">FWHM</sub> =11.6% (at 511 keV) and 1.7-1.9 mm (FWHM) respectively as measured with point-like sources placed in different positions of the FOV. First results from scans of extended phantoms confirmed our expectations.

A prototype of the trigger and digital processing electronics for the electromagnetic calorimeter of the CMS experiment, coupled to a prototype of the PbWO4 crystal calorimeter, was tested during summer 1996 in the H4 beamline at the CERN SPS. A very successful operation was achieved for this system, which runs in synchronous and pipelined mode at the LHC clock frequency, and performs the basic trigger and data acquisition functions needed in the CMS electromagnetic calorimeter. The performance of the trigger front-end electronics is well within the established requirements: a highly efficient bunch-crossing identification (>99.9%), a good trigger-energy resolution (σ/E∼9%/E⊕2%) and a highly efficient electron cluster shape identification (∼99%) have been achieved. The FERMI digitising system based on a dynamic analog compressor and a sampling ADC showed a very good performance, in particular the energy resolution for 150 GeV electrons was 0.54%, equal to the resolution obtained with a conventional charge integration ADC system.

We present experimental results on measuring a single spin asymmetry in η-meson production in the interaction of transversely polarized protons and antiprotons at plab = 200 GeV/c with a proton target in the region 0.2 < xF < 0.7 for p↑p, 0.3 < xF < 0.7 for p̄↑p and 0.7 < pT < 2.0 GeV/c. A comparison of single spin asymmetries in π- and η-meson production is made.

Lead tungstate crystals will be used as calorimetric medium in high energy physics at CERN, in a particularly hostile radiation environment. Methods of testing their behaviour under irradiation are discussed here and are illustrated by some R&D results.

The AX-PET demonstrator is based on a new concept in PET detectors, with LYSO crystals aligned along the z coordinate (patient's axis) and WLS (Wave-length shifter) strips placed orthogonal to them. This kind of structure permits to avoid parallax errors due to different depths of interaction of the photons in the crystals, to register the three coordinates of the impinging photon and to reconstruct Compton events. In this way both the spatial resolution and the sensitivity can be highly improved. Moreover, as both the LYSO crystals and the strips are readout via Geiger-mode Avalanche Photo Diodes (G-APDs) the detector is insensitive to magnetic fields and is then suitable to be used in a combined PET/MRI apparatus. A complete Monte Carlo simulation and dedicated reconstruction software, suited to the particular geometry arrangement, have been developed. The two final modules, each composed by 48 crystals and 156 WLS strips have been built and fully characterized in a dedicated test set-up. The results on the performances of the system obtained with a <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">22</sup> Na point source (0.25 mm diameter) are reported.

Results are given on a search for the decay W±→π±γ with the UA2 detector in pp collisions at √s=630 GeV. No signal for such a process is observed and upper limits on the ration R=Γ(W±→π±γ)/Γ(W±→e±v)<4.9×10−3 and on the branching ratio BR(W±→π±γ)<5.4×10−4 are derived at 95% confidence level.

Hadrons emerging from high-energy collisions, as it is the case for protons and pions at the CERN Large Hadron Collider, can produce a damage to inorganic crystals that is specific and cumulative. The mechanism is well understood as due to bulk damage from fragments caused by fission. In this paper, the existing experimental evidence for lead tungstate, LYSO and cerium fluoride is summarised, a study using FLUKA simulations is described and its results are discussed and compared to measurements. The outcome corroborates the confidence in the predictive power of such simulations applied to inorganic scintillators, which are relevant to their adoption as scintillators for calorimetry.

The principal detector for AGS Experiment 810 is a Time Projection Chamber (TPC) in which it is intended to measure momenta and angles of a major fraction of the charged particles from each light ion collision. This report describes the results of a test of a prototype of the TPC in a beam of (14.6 × 16 = 233.6 GeVc) oxygen ions run in June of this year.

An overview status is given of the Lead Tungstate electromagnetic calorimeter which is being developped for the CMS detector at LHC. This includes the development status of PbW04 crystals, the mechanical design of the calorimeter, the read-out and a brief look into results from test measurements in particle beams.

An overview is given of the Lead Tungstate (PbWO/sub 4/) electromagnetic crystal calorimeter for the CMS detector at the Large Hadron Collider (LHC) at CERN in Geneva. This includes a description of the engineering design, the development of the calorimeter components, the read-out system and results obtained in particle beams.