A shashlik calorimeter with longitudinal segmentation for a linear collider Benvenuti, A.C.; Britvich, I.; Camporesi, T. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2001, Letnik:
461, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Two techniques for longitudinal segmentation of shashlik calorimeters are proposed. Results concerning energy resolution and e/π separation are reported.
DELPHI data collected at centre-of-mass energies up to 208 GeV have been analysed to search for charginos, neutralinos and sfermions in the framework of the Minimal Supersymmetric Standard Model ...(MSSM) with R-parity conservation. No evidence for a signal was found in any of the channels. The results of each search were used to derive limits on production cross-sections and particle masses. In addition, the combined result of all searches excludes regions in the parameter space of the constrained MSSM, leading to limits on the mass of the Lightest Supersymmetric Particle and other supersymmetric particles.
The production of single- and multi-photon events has been studied in the reaction e(+) e(-) --> gamma(gamma) + invisible particles. The data collected with the DELPHI detector during the years 1999 ...and 2000 at centre-of-mass energies between 191 GeV and 209 GeV was combined with earlier data to search for phenomena beyond the Standard Model. The measured number of light neutrino families was consistent with three and the absence of an excess of events beyond that predicted by the Standard Model processes was used to set limits on new physics. Both model-independent searches and searches for new processes predicted by supersymmetric and extra-dimensional models have been made. Limits on new non-standard model interactions between neutrinos and electrons were also determined.
We report on the test beam results and calibration methods using high energy electrons, pions and muons with the CMS forward calorimeter (HF). The HF calorimeter covers a large pseudorapidity region ...(
), and is essential for a large number of physics channels with missing transverse energy. It is also expected to play a prominent role in the measurement of forward tagging jets in weak boson fusion channels in Higgs production. The HF calorimeter is based on steel absorber with embedded fused-silica-core optical fibers where Cherenkov radiation forms the basis of signal generation. Thus, the detector is essentially sensitive only to the electromagnetic shower core and is highly non-compensating (e/h≈5). This feature is also manifest in narrow and relatively short showers compared to similar calorimeters based on ionization. The choice of fused-silica optical fibers as active material is dictated by its exceptional radiation hardness. The electromagnetic energy resolution is dominated by photoelectron statistics and can be expressed in the customary form as
. The stochastic term a is 198% and the constant term b is 9%. The hadronic energy resolution is largely determined by the fluctuations in the neutral pion production in showers, and when it is expressed as in the electromagnetic case, a = 280% and b = 11%.
An electromagnetic shashlik calorimeter with longitudinal segmentation Benvenuti, A.C; Britvich, I; Camporesi, T ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/1999, Letnik:
432, Številka:
2-3
Journal Article
Recenzirano
Odprti dostop
A novel technique for longitudinal segmentation of shashlik calorimeters has been tested in the CERN West Area beam facility. A 25 tower very fine samplings e.m. calorimeter has been built with ...vacuum photodiodes inserted in the first 8 radiation lengths to sample the initial development of the shower. Results concerning energy resolution, impact point reconstruction and e/π separation are reported.
In the frame of research and development for electromagnetic calorimetry at future e/sup +/e/sup -/ linear colliders, different techniques have been studied to implement longitudinal segmentation in ...Shashlik calorimeters. Two prototypes with 5/spl times/5 cm/sup 2/ lead/scintillator towers and readout by means of wavelength-shifting fibers have been built. The longitudinal segmentation of the shower is achieved by modifying the front part of the detector. In the first prototype, vacuum photodiodes have been inserted laterally for the first eight X/sub 0/, while in the second prototype a slow scintillator has been used in the first five X/sub 0/. Both of the prototypes have been exposed to beam at CERN. The performance in term of energy resolution, spatial resolution, and e//spl pi/ separation are described.
Moments of the hadronic invariant mass and of the lepton energy spectra in semileptonic B decays have been determined with the data recorded by the DELPHI detector at LEP. From measurements of the ...inclusive b-hadron semileptonic decays, and imposing constraints from other measurements on b- and c-quark masses, the first three moments of the lepton energy distribution and of the hadronic mass distribution, have been used to determine parameters which enter into the extraction of |V_cb| from the measurement of the inclusive b-hadron semileptonic decay width. The values obtained in the kinetic scheme are: m_b(1 GeV) = 4.591 +/- 0.062 +/- 0.039 +/- 0.005 GeV/c^2 m_c(1 GeV) = 1.170 +/- 0.093 +/- 0.055 +/- 0.005 GeV/c^2 mu_{pi}^2(1 GeV) = 0.399 +/- 0.048 +/- 0.034 +/- 0.087 GeV^2 \tilde{\rho}_D^3 = 0.053 +/- 0.017 +/- 0.011 +/- 0.026 GeV^3, and include corrections at order 1/m_b^3. Using these results, and present measurements of the inclusive semileptonic decay partial width of b-hadrons at LEP, an accurate determination of |V_cb| is obtained: |V_cb| = 0.0421 x (1 +/- 0.014 (meas.) +/- 0.014 (fit) +/- 0.015 (th.)).
Extensive measurements have been made with pions, electrons and muons on four production wedges of the compact muon solenoid (CMS) hadron barrel (HB) calorimeter in the H2 beam line at CERN with ...particle momenta varying from 20 to 300 GeV/
c
. The time structure of the events was measured with the full chain of preproduction front-end electronics running at 34 MHz. Moving-wire radioactive source data were also collected for all scintillator layers in the HB. The energy dependent time slewing effect was measured and tuned for optimal performance.
The DELPHI detector at LEP has been used to measure multi-muon bundles originating from cosmic ray interactions with air. The cosmic events were recorded in “parasitic mode” between individual e
+e
− ...interactions and the total live time of this data taking is equivalent to 1.6
×
10
6
s. The DELPHI apparatus is located about 100
m underground and the 84 metres rock overburden imposes a cutoff of about 52
GeV/c on muon momenta. The data from the large volume Hadron Calorimeter allowed the muon multiplicity of 54,201 events to be reconstructed. The resulting muon multiplicity distribution is compared with the prediction of the Monte Carlo simulation based on CORSIKA/QGSJET01. The model fails to describe the abundance of high multiplicity events. The impact of QGSJET internal parameters on the results is also studied.
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