H. Rykaczewski

We report the analysis of the spatial energy distribution of data for ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}\mathrm{hadrons}$ obtained with the MARK-J detector at PETRA. We define the quantity "oblateness" to describe the flat shape of the energy configuration and the three-jet structure which is unambiguously observed for the first time. Our data can be explained by quantum chromodynamic predictions for the production of quark-antiquark pairs accompanied by hard noncollinear gluons.

Measurements of the total cross section have been performed at the ISR with c.m. energies between 23.5 GeV and 62.5 GeV. Two independent experimental methods have been applied, a measurement of total interaction rate and of small angle elastic scattering. Both experiments give consistent results showing that the total cross section increases by (11.8±1.5) % over the ISR energy range. This experiment has also measured the slope of the forward diffraction peak in elastic scattering at small momentum transfer. The elastic cross section shows the same relative rise as the total cross section, and the ratio λ of elastic to total cross section approaches a constant value of λ=0.178±0.003.

Measurements of the reactions ${e}^{+}+{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{e}^{+}+{e}^{\ensuremath{-}}$, ${\ensuremath{\mu}}^{+}+{\ensuremath{\mu}}^{\ensuremath{-}}$, and ${\ensuremath{\tau}}^{+}+{\ensuremath{\tau}}^{\ensuremath{-}}$ at PETRA energies (${s}^{\frac{1}{2}}=13,17,27.4,30 \mathrm{and} 31.6$ GeV) are reported. The results show that these reactions agree well with the predictions of quantum electrodynamics thus determining that all the known charged leptons are pointlike particles to a distance \ifmmode\times\else\texttimes\fi{} ${10}^{\ensuremath{-}16}$ cm.

PETRA, the e+e− collider, has operated at a maximum CM energy of 46.78 GeV. We update our previous results on new particle searches and set significantly better mass limits on some.

The exotic phenomena that can be studied in high energy esup(+-)p collisions are reviewed using the HERA ep collider as an example. Unique mass ranges, upto 180-200 GeV, are possible in the detection of new particles (leptoquarks, leptons, quarks, SUSY particles,...) and electron quark scattering can probe substructure at the 3-5 TeV mass scale as well as infer the existence of new currents corresponding to bosons (W',Z') of masses upto 500 GeV.

We report the measurement of the reaction e+ + e− → hadronic jets at a center-of-mass energy √s=30 GeV using the MARK-J detector at PETRA. By measuring the energy and angular distribution of both neutrals and charged particles we were able to isolate unambiguously the three-jet events in a kinematic region where the backgrounds from qq and phase space contributions and other processes are small. Various comparisons of the data with quantum chromodynamics were made. The relative yield of three-jet events and the shape distribution of the events enable us to determine αs = 0.23 ± 0.02 (statistical error) with a systematic error of ± 0.04.

The results of a high-statistics study of inclusive muon spectra at PETRA are reported.Improved mass limits have been obtained for heavy quarks, heavy leptons, and charged Higgs particles.It is shown that the fragmentation properties of b quarks and c quarks

This report reviews the experimental investigation of high energy e+e− interactions by the MARK J collaboration at PETRA, the electron-positron colliding beam accelerator at DESY in Hamburg, Germany. The physics objectives include studies of several purely electromagnetic processes and hadronic final states, which further our knowledge of the nature of the fundamental constituents and of their strong, electromagnetic and weak interactions. Before discussing the physics results, the main features and the principal components of the MARK J detector are discussed in terms of design, function, and performance. Several aspects of the on-line data collection and the off-line analysis are also outlined. Results are presented on tests of quantum electrodynamics using e+e− → e+e−, μ+μ− and τ+τ−, on the measurement of R, the ratio of the hadronic to the point-like muon pair cross section, on the search for new quark flavors, on the discovery of three jet events arising from the radiation of hard noncollinear gluons as predicted by quantum chromodynamics, and on the determination of the strong coupling constant αs.

With use of the MARK-J detector at $\sqrt{s}=34.7$ GeV 21 000 ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}\mathrm{hadron}$ events have been collected. By measurement of the asymmetry in angular energy correlations the strong coupling constant ${\ensuremath{\alpha}}_{s}=0.13\ifmmode\pm\else\textpm\fi{}0.01 (\mathrm{statistical})\ifmmode\pm\else\textpm\fi{}0.02 (\mathrm{systematic})$ is determined, in complete second order, and independent of the fragmentation models and QCD cutoff values used.

With a PETRA energy scan in \ensuremath{\le}30-MeV steps, the continuum production of open top quark up to 38.54 GeV is excluded. Over regions of energy scan from 29.90 to 38.63 GeV limits are set on the product of hadronic branching ratio and electronic width ${B}_{h}{\ensuremath{\Gamma}}_{\mathrm{ee}}$ for toponium to be less than 2.0 keV at the 95% confidence level. By a search for flavor-changing neutral currents in $b$ decay, models without a top quark are excluded.

The measurement of the nonelectromagnetic forward-backward charge asymmetry in the reaction e+eiz'tz at ~s-34.6 GeV and in the angular region 0& IcosOI&0.8 is re- ported.With a systematic error less than 1%, we observe an asymmetry of (-8.1+2.1)/p.This is in agreement with the standard electroweak theory prediction of (-7.6+ 0.6)%.The weak-current coupling constants are also reported.

The design and operation of precision drift chambers with multisampling as well as the concepts and methods for reaching an extraordinary degree of precision in mechanics and calibration are described. Specific instruments were developed for this purpose. The concept of reproducible positioning and the implementation to 30 μm accuracy, showing stability over three years, is given. Calibration and analysis with UV-laser and cosmic test measurements are outlined with the critical results. The experience of calibration and reliability of the large system in an actual L3 running experiment is analyzed. The resolution under “battle conditions” at LEP resulted in Δpp = (2.50±0.04)% at 45.6 GeV and will be presented in detail. The concept is well suited for future TeV energies.

We have performed a high-statistics measurement of Bhabha scattering and of the production of hadrons in electron-positron annihilation at PETRA energies ($12 \mathrm{GeV}<~\sqrt{s}<~36.7 \mathrm{GeV}$). Combining the results with measurements of ${\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$ and ${\ensuremath{\tau}}^{+}{\ensuremath{\tau}}^{\ensuremath{-}}$ production enables us to compare our results with electroweak theory. We find ${{sin}^{2}\ensuremath{\theta}}_{w}=0.27\ifmmode\pm\else\textpm\fi{}0.08$. This is in good agreement with the value obtained from neutrino experiments which were carried out in entirely different kinematic regions.

By combining results from the MARK-J at PETRA on Bhabha scattering, μ+μ- and τ+τ- production with recent world data from neutrino-electron scattering experiments, we determine unique values for the leptonic weak neutral current coupling constants gV and gA in the framework of electroweak models containing a single Z0. In contrast to previous analyses, we only use data from purely leptonic interactions, and therefore avoid the inherent uncertainties resulting from the use of hadronic targets. From the MARK-J data alone in the context of the standard SU(2) ⊗ U (1) model of Glashow, Weinberg and Salam, we find sin2θW=0.24±0.11.

This paper reports the results of a study of hadron production in e+e− collisions at c.m. system energies of 33, 35, and 35.8 GeV. Production of a new quark flavor has been sought. The measured values of the total cross section, the thrust distributions, and the study of inclusive muon production show no evidence for the production of a new charge-23e quark near threshold. In addition, during an energy scan in the region 29.9<~√s<~31.6 GeV, no hadron resonance indicating the existence of a bound state composed of charge-23e quarks has been found.Received 1 April 1980DOI:https://doi.org/10.1103/PhysRevLett.44.1722©1980 American Physical Society

We report on the measurement of the reaction ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{e}^{+}{e}^{\ensuremath{-}}$ with a large---solid-angle electromagnetic shower detector at center-of-mass energies $\sqrt{s}=13 \mathrm{and} 17$ GeV. Comparison of our results with predictions of quantum electrodynamics shows excellent agreement in both the angular distribution and energy dependence. Values of cutoff parameters are also given.

We report the first measurement of the ratio R=(σe+e−→hadrons)(σe+e−→μ+μ−) (with negligible τ-lepton contribution) at a center-of-mass energy s=13 GeV and s=17 GeV, from the just finished electron-positron colliding-beam facility PETRA. The detector, MARK-J, has an approximately 4π solid angle and measures γ, e, μ, and charged and neutral hadrons simultaneously. Our results yield R(s=17 GeV)=4.9±0.6 (statistical) ±0.7 (systematic error), and R(s=13 GeV)=4.6±0.5 (statistical) ±0.7 (systematic error). The ratio R(s=17 GeV)R(s=13 GeV) is 1.08±0.18.Received 6 February 1979DOI:https://doi.org/10.1103/PhysRevLett.42.1113©1979 American Physical Society

The results are reported of a search for excited muons (${\ensuremath{\mu}}^{*}$) and electrons (${e}^{*}$) and for a stable charged heavy lepton by measurements of the ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}\ensuremath{\gamma}$, ${\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}\ensuremath{\gamma}$, ${\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}\ensuremath{\gamma}\ensuremath{\gamma}$, and $\ensuremath{\gamma}\ensuremath{\gamma}$ final states. Excluded are large regions of the $\ensuremath{\lambda}$ (coupling constant), $M$ (mass) planes for spin-\textonehalf{} ${\ensuremath{\mu}}^{*}$ and ${e}^{*}$, and a new stable charged heavy lepton with mass 14 GeV.

We use the reaction e+ e p, + p, , in the Mark J detector at the DESY high-energy e+ e col- lider PETRA, to test the standard electroweak theory and find good agreement.We also set limits on the parameters of several extended gauge theories.

We report mass limits on the ${\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{Z}}^{0}$ and ${\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{W}}^{\ifmmode\pm\else\textpm\fi{}}$, supersymmetric partners of the ${Z}^{0}$ and ${W}^{\ifmmode\pm\else\textpm\fi{}}$, respectively, using the MARK-J detector at PETRA. The experimental signatures in both cases are acoplanar lepton pairs with missing energy. For the ${\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{W}}^{\ifmmode\pm\else\textpm\fi{}}$, an additional signature is a single energetic lepton. No evidence is found for either the ${\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{Z}}^{0}({M}_{{\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{Z}}^{0}}&lt;35\mathrm{GeV})$ or the ${\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{W}}^{\ifmmode\pm\else\textpm\fi{}}({M}_{\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{W}}&lt;25\mathrm{GeV})$.

We have used our measurements of final states from e+e− containing an isolated muon and a hadronic or electron shower to search for new spin 0 charged particles. We exclude (95% CL) a supersymmetric partner of the τ with a mass less than 14 GeV/c2. We obtain upper limits on the branching ratio to τvτ for charged Higgs particles or technipions with masses up to 14 GeV/c2. This disagrees with some technicolor model predictions.

We have searched for resonances in the reaction ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}\mathrm{hadrons}, \ensuremath{\gamma}\ensuremath{\gamma}, \ensuremath{\mu}\ensuremath{\mu}, \mathrm{and} \mathrm{ee}$, in the energy range $39.79&lt;\sqrt{s}&lt;45.52$ GeV, using the Mark J detector at PETRA. We obtain stringent upper limits on the production of toponium and particles postulated to explain ${Z}^{0}\ensuremath{\rightarrow}\mathrm{lepton}\mathrm{pair}+\ensuremath{\gamma}$ events observed at the CERN $\stackrel{-}{p}p$ collider. We also set limits on the mass and coupling constant of excited electrons.

We use the reaction e+e−→hadrons, in the Mark J detector at the DESY electron-positron collider PETRA, to determine the hadronic cross section up to 46.78 GeV. The production of a top quark with a charge equal to (2/3) is excluded up to 46.6 GeV with 95% C.L. The observed rise in the cross section at higher energies is consistent with the electroweak prediction for a Z0 mass of 93 GeV. We describe some unusual muon inclusive events.Received 27 January 1986DOI:https://doi.org/10.1103/PhysRevD.34.681©1986 American Physical Society

CMS (compact muon solenoid) is a general-purpose detector designed to run at the highest luminosity at the CERN Large Hadron Collider (LHC). Its distinctive features include a 4 T superconducting solenoid with 6 m diameter by 12.5 m long free bore, enclosed inside a 10,000-ton return yoke. The stored magnetic energy is 2.6 GJ. The magnet is being assembled in a surface hall and will be tested at the beginning of 2005 before being transferred to an experimental hall 90 m below ground level. The design and construction of the magnet is a common project of the CMS Collaboration. The task is organized by a CERN based group with strong technical and contractual participation of CEA Saclay, ETH Zurich, Fermilab, INFN Genova, ITEP Moscow, University of Wisconsin and CERN. The return yoke, 21 m long and 14 m in diameter, is equivalent to a thickness of 1.5 m of saturated iron interleaved with four muon stations. Manufacture of the yoke and vacuum tank is completed and the first sub-detectors have been installed. The indirectly-cooled, pure-aluminum-stabilized coil is made up from five modules internally wound with four layers of a 20 kA mechanically-reinforced conductor. The manufacture of the conductor is completed and winding is in progress for a final assembly in 2004. All ancillaries are delivered or under contract. The magnet project is described, with emphasis on the present status of the fabrication.

This paper reports on the first results of the study of e+e collisions at 4's =27.4 GeV and vs = 27.7 GeV at PETRA, using the 47'-sr electromagnetic and calorimetric detector MARK-J.We obtain an average A=a(e+e hadrons)/o(e+e p+p ) = 8.8+0.3 (statis- tical) + 0.6 (systematic) and a relative R = 1.0+ 0.2 between the two energies.The R values, the measured thrust distribution, and average spherocity show no evidence for the production of new quark flavors.

We report on the results of the study of e+e− collisions at the highest PETRA energy of √s = 31.57 GeV, using the 4π sr, electromagnetic and calorimetric detector Mark J. Based on 88 hadron events, and an integrated luminosity of 243 nb−1 we obtain R = σ(e+e− → hadrons)/σ(e+e− → μ+μ−) = 4.0 ± 0.5 (statistical) ± 6 (systematic). The R value, the measured thrust distribution and average spherocity show no evidence for the production of new quark flavors.

A Higgs particle produced in association with a Z boson and decaying into two photons is searched for in the data collected by the L3 experiment at LEP. All possible decay modes of the Z boson are investigated. No signal is observed in 447.5 pb^-1 of data recorded at centre-of-mass energies up to 209 GeV. Limits on the branching fraction of the Higgs boson decay into two photons as a function of the Higgs mass are derived. A lower limit on the mass of a fermiophobic Higgs boson is set at 105.4 GeV at 95% confidence level.

Using the Mark-J detector at the high-energy ${e}^{+}{e}^{\ensuremath{-}}$ collider PETRA, we compare the data from hadron production with the complete second-order QCD calculation over the energy region 22 to 46.78 GeV. We determine the QCD parameter $\ensuremath{\Lambda}=100\ifmmode\pm\else\textpm\fi{}{30}_{\ensuremath{-}45}^{+60}$ MeV which yields the strong-coupling constant ${\ensuremath{\alpha}}_{s}=0.12\ifmmode\pm\else\textpm\fi{}0.02$ for $\sqrt{s}=44$ GeV.

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 Mark J Collaboration at the DESY e+e− collider PETRA presents results on the electroweak reactions e+e−→μ+μ−τ+τ−,μ+μ−γ, and e+e−μ+μ−. The c.m. energy range is 12 to 46.78 GeV. In the μ+μ− and τ+τ− channels the total cross sections and the forward-backward asymmetries are reported and compared with other experiments. The results are in excellent agreement with the standard model. The weak-neutral-current vector and axial-vector coupling constants are determined. The values for muons and τ’s are compatible with universality and with the predictions of the standard model. In the μ+μ−γ channel, all measured distributions, including the forward-backward muon asymmetry, are in excellent agreement with the electroweak theory. Our data on the two-photon process, e+e−μ+μ−, agrees with QED to order α4 over the entire energy range and the Q2 range from 0.7 to 166 GeV2.Received 29 April 1988DOI:https://doi.org/10.1103/PhysRevD.38.2665©1988 American Physical Society

A study of τ-lepton production in the CMS energy region from 14 to 46.8 GeV at PETRA is reported. The cross section, the decay branching ratio into μνν, and the electroweak parameters are determined with a total integrated luminosity of 115 pb−1.

We have performed a high statistics measurement of the production rate and the energy flow pattern of hadron events between √s=33 and 36.7 GeV. The data show no evidence for the production of a new quark with charge 23e. Planar events in e+e−→hadrons are shown to have three well separated jets. The production rate and the shape of three-jet events are compared with many models and we find that only the QCD model can explain the data.

Abstract We present a design study, based on our experience in the construction of the L3 detector at LEP, of a large solid angle muon detector for a high luminosity (> 10 33 cm −2 /sec) pp collider. It is shown that a resolution of ΔM / M ∼ 1% can be reached for a one TeV particle T→ μ + μ − . Hadron jets can also be measured.

A direct test is presented of higher-order QED (${\ensuremath{\alpha}}^{4}$) at large momentum transfers (up to \ensuremath{\sim}100 Ge${\mathrm{V}}^{2}$). These tests were carried out with the MARK-J detector at PETRA by comparing the measured cross section for the process ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{e}^{+}{e}^{\ensuremath{-}}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$ with the prediction of QED for $12 \mathrm{GeV}&lt;~\sqrt{s}&lt;~36.7 \mathrm{GeV}$. The cross sections and the various kinematic distributions agree with QED.

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.

We have measured the probability, n(g->cc~), of a gluon splitting into a charm-quark pair using 1.7 million hadronic Z decays collected by the L3 detector. Two independent methods have been applied to events with a three-jet topology. One method relies on tagging charmed hadrons by identifying a lepton in the lowest energy jet. The other method uses a neural network based on global event shape parameters. Combining both methods, we measure n(g->cc~)= [2.45 +/- 0.29 +/- 0.53]%.

The strong interaction coupling constant αs has been measured with a new method, the planar triple energy correlation in the reaction e+e- → hadrons at center-of-mass energies ranging from 14 GeV to 46.78 GeV. A complete second-order perturbative QCD calculation was used. ΛMS = 110 ± 30 −55+70 MeV is found.

The L3 detector is designed to measure the muon momentum with a 2% resolution at p = 45 GeV/c. We discuss here the systems we developed to reach the required accuracy and control the mechanical alignment at running time. We also report on the test done on the muon spectrometer with UV lasers and cosmic rays.

The L3 muon spectrometer is presented. Characteristics, useful for experiments at future accelerators, are highlighted. Particular emphasis is given to the systems envisaged to keep the error on the relative alignment of detectors below 30 μm and so reach a momentum resolution Δpp = 2% at p = 45 GeV/c.

We study the production of single γ, e and μ at high πt using the high energy data of the Mark-J detector at PETRA. We find good agreement with QED. We give mass limits of the SUSY particles γ̃, ṽ, ẽ and W̃ studying the associated production of W̃ and ẽ and radiative production of pairs of γ̃ or ṽ in three-body reactions.

The Atacama Large Millimeter and Submillimeter Array (ALMA) will provide an unprecedented combination of sensitivity, angular resolution, spectral resolution, and imaging fidelity at the shortest radio wavelengths for which the Earth’s atmosphere is transparent. The three major scientific goals for ALMA can be summarised as: to detect spectral line emission from CO or C ii at a redshift of z = 3 in less than 24 h of observation; to image gas kinematics in protostars and protoplanetary discs at a distance of 150 pc, enabling the study of the physical, chemical and magnetic field structures; to provide images with an angular resolution of 0.1?.

The Atacama Large Millimeter/submillimeter Array (ALMA) is the largest astronomical ground based global collaboration. The project is a partnership of organisations and institutes located in four continents, each bringing its own organisational structures, scientific objectives, and management. This brings a richness of different experiences and expertise to the project, but is also a challenge to build and provide the public and the science users a unified project. In this talk we will review the ALMA organisation and management structure, its successes, difficulties and experience gained for future projects of similar complexity and challenge.

Measurements of cosmic rays in the L3 multisampling chambers are presented. The study of tracks with polar angles from 30° < θ < 130° w.r.t. the wires show increasing pulse height like 1/sin θ. Using inclined tracks, we find a ±1.5 cm region of reduced accuracy near the glass supports of the 5.4 m long wires.

Data from the MARK-J detector on the reactions e/sup +/e/sup -/..--> mu../sup +/..mu../sup -/,tau/sup +/tau/sup -/ in the center-of-mass energy range from 12 to 36.7 GeV are presented. The ..mu..,tau radii are shown to be <10/sup -16/ cm. A search has been made for the production of a new heavy lepton and for the production of spin-0 supersymmetric partners of the muon. 95%-confidence-level lower limits of 16 GeV for the mass of a new charged heavy lepton and 15 GeV for the mass of the scalar partners of the muon are obtained.

Data from the MARK-J detector on the reactions ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$, ${\ensuremath{\tau}}^{+}{\ensuremath{\tau}}^{\ensuremath{-}}$ in the center-of-mass energy range from 12 to 36.7 GeV are presented. The $\ensuremath{\mu}$, $\ensuremath{\tau}$ radii are shown to be ${10}^{\ensuremath{-}16}$ cm. A search has been made for the production of a new heavy lepton and for the production of spin-0 supersymmetric partners of the muon. 95%-confidence-level lower limits of 16 GeV for the mass of a new charged heavy lepton and 15 GeV for the mass of the scalar partners of the muon are obtained.