Test beam results for an upgraded forward tagger of the L3 experiment at LEP II

doi:10.1016/0168-9002(94)91198-3

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

Volume 349, Issues 2–3, 1 October 1994, Pages 345-355

https://doi.org/10.1016/0168-9002(94)91198-3 Get rights and content

Abstract

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.

References (11)

B. Adeva
Nucl. Instr. and Meth. A
(1990)
M. Goyot
Nucl. Instr. and Meth. A
(1988)
B. Mouëllic
Note CERN/PS202
(1989)
M. Chemarin et al., to be...
B. Bertucci
Upgrade of the Active Lead Ring (ALR) for LEP200 Physics

There are more references available in the full text version of this article.

Cited by (169)

Analysis of the π+ π- π+ π- and π+ π0 π- π0 final states in quasi-real two-photon collisions at LEP
2006, Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
The reactions $γ γ \to π^{+} π^{-} π^{+} π^{-}$ and $γ γ \to π^{+} π^{0} π^{-} π^{0}$ are studied with the L3 detector at LEP in a data sample collected at centre-of-mass energies from 161 GeV to 209 GeV with a total integrated luminosity of 698 pb⁻¹. A spin-parity-helicity analysis of the $ρ^{0} ρ^{0}$ and $ρ^{+} ρ^{-}$ systems for two-photon centre-of-mass energies between 1 and 3 GeV shows the dominance of the spin-parity state $2^{+}$ with helicity 2. The contribution of $0^{+}$ and $0^{-}$ spin-parity states is also observed, whereas contributions of $2^{-}$ states and of a state with spin-parity $2^{+}$ and zero helicity are found to be negligible.
Precision electroweak measurements on the Z resonance
2006, Physics Reports
Citation Excerpt :
The experimental details of the four measurements are sufficiently different that no correlations are considered to exist in the experimental component of the luminosity errors. All four collaborations, however, use BHLUMI 4.04 [23], the best available Monte Carlo generator for small-angle Bhabha scattering, to calculate the accepted cross-section of their luminosity counters. Therefore significant correlations exist in the errors assigned to the scale of the measured cross-sections due to the uncertainty in this common theoretical calculation.
We report on the final electroweak measurements performed with data taken at the Z resonance by the experiments operating at the electron–positron colliders SLC and LEP. The data consist of 17 million Z decays accumulated by the ALEPH, DELPHI, L3 and OPAL experiments at LEP, and 600 thousand Z decays by the SLD experiment using a polarised beam at SLC. The measurements include cross-sections, forward–backward asymmetries and polarised asymmetries. The mass and width of the Z boson, $m_{Z}$ and $Γ_{Z}$ , and its couplings to fermions, for example the $ρ$ parameter and the effective electroweak mixing angle for leptons, are precisely measured:The number of light neutrino species is determined to be $2.9840 \pm 0.0082$ , in agreement with the three observed generations of fundamental fermions.
The results are compared to the predictions of the Standard Model (SM). At the Z-pole, electroweak radiative corrections beyond the running of the QED and QCD coupling constants are observed with a significance of five standard deviations, and in agreement with the Standard Model. Of the many Z-pole measurements, the forward–backward asymmetry in b-quark production shows the largest difference with respect to its SM expectation, at the level of 2.8 standard deviations.
Through radiative corrections evaluated in the framework of the Standard Model, the Z-pole data are also used to predict the mass of the top quark, $m_{t} = 173_{- 10}^{+ 13} GeV$ , and the mass of the W boson, $m_{W} = 80.363 \pm 0.032 GeV$ . These indirect constraints are compared to the direct measurements, providing a stringent test of the SM. Using in addition the direct measurements of $m_{t}$ and $m_{W}$ , the mass of the as yet unobserved SM Higgs boson is predicted with a relative uncertainty of about 50% and found to be less than $285 GeV$ at 95% confidence level.
Measurement of the running of the electromagnetic coupling at large momentum-transfer at LEP
2005, Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
The evolution of the electromagnetic coupling, α, in the momentum-transfer range $1800 {GeV}^{2} < - Q^{2} < 21600 {GeV}^{2}$ is studied with about 40 000 Bhabha-scattering events collected with the L3 detector at LEP at centre-of-mass energies $\sqrt{s} = 189 – 209 GeV$ . The running of α is parametrised as: where $α_{0} \equiv α (Q^{2} = 0)$ is the fine-structure constant and $C = 1$ corresponds to the evolution expected in QED. A fit to the differential cross section of the $e^{+} e^{-} \to e^{+} e^{-}$ process for scattering angles in the range $| \cos θ | < 0.9$ excludes the hypothesis of a constant value of α, $C = 0$ , and validates the QED prediction with the result: where the first uncertainty is statistical and the second systematic.
Measurement of the photon structure function F<inf>2</inf>γ with the L3 detector at LEP
2005, Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
The $e^{+} e^{-} \to e^{+} e^{-} hadrons$ reaction, where one of the two electrons is detected in a low polar-angle calorimeter, is analysed in order to measure the hadronic photon structure function $F_{2}^{γ}$ . The full high-energy and high-luminosity data set, collected with the L3 detector at centre-of-mass energies $189 GeV ⩽ \sqrt{s} ⩽ 209 GeV$ , corresponding to an integrated luminosity of 608 pb⁻¹ is used. The $Q^{2}$ range $11 {GeV}^{2} ⩽ Q^{2} ⩽ 34 {GeV}^{2}$ and the x range $0.006 ⩽ x ⩽ 0.556$ are considered. The data are compared with recent parton density functions.
Measurement of the cross section for open-beauty production in photon-photon collisions at LEP
2005, Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
The cross section for open-beauty production in photon–photon collisions is measured using the whole high-energy and high-luminosity data sample collected by the L3 detector at LEP. This corresponds to 627 pb⁻¹ of integrated luminosity for electron–positron centre-of-mass energies from 189 to 209 GeV. Events containing b quarks are identified through their semi-leptonic decay into electrons or muons. The $e^{+} e^{-} \to e^{+} e^{-} b \bar{b} X$ cross section is measured within our fiducial volume and then extrapolated to the full phase space. These results are found to be in significant excess with respect to Monte Carlo predictions and next-to-leading order QCD calculations.
Compton scattering of quasi-real virtual photons at LEP
2005, Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
Compton scattering of quasi-real virtual photons, $γ e^{\pm} \to γ e^{\pm}$ , is studied with 0.6 fb⁻¹ of data collected by the L3 detector at the LEP $e^{+} e^{-}$ collider at centre-of-mass energies $\sqrt{s} = 189 – 209 GeV$ . About 4500 events produced by the interaction of virtual photons emitted by $e^{\pm}$ of one beam with $e^{\mp}$ of the opposite beam are collected for effective centre-of-mass energies of the photon–electron and photon–positron systems in the range from $\sqrt{s^{'}} = 35 GeV$ up to $\sqrt{s^{'}} = 175 GeV$ , the highest energy at which Compton scattering was ever probed. The cross sections of the $γ e^{\pm} \to γ e^{\pm}$ process as a function of $\sqrt{s^{'}}$ and of the rest-frame scattering angle are measured, combined with previous L3 measurements down to $\sqrt{s^{'}} ≃ 20 GeV$ , and found to agree with the QED expectations.

View all citing articles on Scopus

^∗: corresponding author.

¹: Now at Eidgenössische Technische Hochschule, Zürich, Switzerland.

View full text

Article preview

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

Abstract

References (11)

Nucl. Instr. and Meth. A

Nucl. Instr. and Meth. A

Note CERN/PS202

Upgrade of the Active Lead Ring (ALR) for LEP200 Physics

Cited by (169)

Analysis of the π<sup>+</sup> π<sup>-</sup> π<sup>+</sup> π<sup>-</sup> and π<sup>+</sup> π<sup>0</sup> π<sup>-</sup> π<sup>0</sup> final states in quasi-real two-photon collisions at LEP

Precision electroweak measurements on the Z resonance

Measurement of the running of the electromagnetic coupling at large momentum-transfer at LEP

Measurement of the photon structure function F<inf>2</inf><sup>γ</sup> with the L3 detector at LEP

Measurement of the cross section for open-beauty production in photon-photon collisions at LEP

Compton scattering of quasi-real virtual photons at LEP