We apply a quasi-model-independent strategy ("Sleuth") to search for new high p(T) physics in approximately 100 pb(-1) of pp collisions at square root of (s) = 1.8 TeV collected by the D0 experiment ...during 1992-1996 at the Fermilab Tevatron. We systematically analyze many exclusive final states and demonstrate sensitivity to a variety of models predicting new phenomena at the electroweak scale. No evidence of new high p(T) physics is observed.
B-physics results from DØ Baarmand, M.M.
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/1998, Letnik:
408, Številka:
1
Journal Article
Recenzirano
A number of B-physics results from the DØ
experiment at the Fermilab Tevatron Collider are reported. Measurements of
b
b
̄
production in
p
p
̄
interactions at
s
=1800
and 630
GeV are used to ...evaluate, for the first time with the same detector, the center-of-mass energy and rapidity dependence of b-quark production cross section. A measurement of the
b
b
̄
angular correlations using dimuon triggers is also presented. Preliminary results from these measurements are compared with the next-to-leading order QCD predictions. Finally, dimuon data samples are used to study
p
T and rapidity dependence of b-produced and direct charmonium productions.
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%.
A simple network of comparators applied to the strip signals of a cathode strip chamber allows quick hit localization to within a halfstrip width, or ± a quarter-strip. A six-plane chamber with 6.4
...mm wide strips was tested in a high-energy muon beam. The chamber was placed behind a 30
cm thick iron block. We show that patterns of hits localized to within a halfstrip allowed us to identify 300
GeV/c muon tracks with 99% probability and 0.7
mm spatial resolution in the presence of bremsstrahlung radiation. This technique of finding muon tracks will be used in the cathode strip chambers of the CMS Endcap Muon System.
A search for exotic unstable neutral and charged heavy leptons as well as for stable charged heavy leptons is performed with the L3 detector at LEP. Sequential, vector and mirror natures of heavy ...leptons are considered. No evidence for their existence is found and lower limits on their masses are set.
The response of the CMS barrel calorimeter (electromagnetic plus hadronic) to hadrons, electrons and muons over a wide momentum range from 2 to 350 GeV/
c
has been measured. To our knowledge, this is ...the widest range of momenta in which any calorimeter system has been studied. These tests, carried out at the H2 beam-line at CERN, provide a wealth of information, especially at low energies. The analysis of the differences in calorimeter response to charged pions, kaons, protons and antiprotons and a detailed discussion of the underlying phenomena are presented. We also show techniques that apply corrections to the signals from the considerably different electromagnetic (EB) and hadronic (HB) barrel calorimeters in reconstructing the energies of hadrons. Above 5 GeV/
c
, these corrections improve the energy resolution of the combined system where the stochastic term equals 84.7±1.6% and the constant term is 7.4±0.8%. The corrected mean response remains constant within 1.3%
rms
.
Tests of cathode strip chamber prototypes Baarmand, M.M; Bonushkin, Yu; Chrisman, D ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
1998, 1998-1-00, Letnik:
402, Številka:
1
Journal Article
Recenzirano
Odprti dostop
We report on the results of testing two six-layer 0.6 × 0.6 m
2 cathode strip chamber (CSC) prototypes in a muon beam at CERN. The prototypes were designed to simulate sections of the end-cap muon ...system of the Compact Muon Solenoid (CMS) detector which will be installed at the Large Hadron Collider (LHC). We measured the spatial and time resolutions of each chamber for different gains, different orientations with respect to the beam direction and different strength magnetic fields. The single-layer spatial resolution of a prototype with a strip pitch of 15.88 mm ranged from 78 to 468 μm, depending on whether the particle passed between two cathode strips or through the center of a strip; its six-layer resolution was found to be 44 μm. The single-layer spatial resolution of a prototype with a strip pitch of 6.35 mm ranged from 54 to 66 μm; its six-layer resolution was found to be 23 μm. The efficiency for collecting an anode wire signal from one of six layers within a 20 ns time window appropriate for the LHC was found to be greater than 95% in normal running conditions.
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.
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