We present our new measurement of the cross-section for charm dimuon production in neutrino–iron interactions based upon the full statistics collected by the NOMAD experiment. After background ...subtraction we observe 15 344 charm dimuon events, providing the largest sample currently available. The analysis exploits the large inclusive charged current sample – about 9×106 events after all analysis cuts – and the high resolution NOMAD detector to constrain the total systematic uncertainty on the ratio of charm dimuon to inclusive Charged Current (CC) cross-sections to ∼2%. We also perform a fit to the NOMAD data to extract the charm production parameters and the strange quark sea content of the nucleon within the NLO QCD approximation. We obtain a value of mc(mc)=1.159±0.075 GeV/c2 for the running mass of the charm quark in the MS¯ scheme and a strange quark sea suppression factor of κs=0.591±0.019 at Q2=20 GeV2/c2.
Prediction of neutrino fluxes in the NOMAD experiment Astier, P; Autiero, D; Baldo-Ceolin, M ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2003, Letnik:
515, Številka:
3
Journal Article
Recenzirano
Odprti dostop
The method developed for the calculation of the flux and composition of the West Area Neutrino Beam used by NOMAD in its search for neutrino oscillations is described. The calculation is based on ...particle production rates computed using a recent version of FLUKA and modified to take into account the cross-sections measured by the SPY and NA20 experiments. These particles are propagated through the beam line taking into account the material and magnetic fields they traverse. The neutrinos produced through their decays are tracked to the NOMAD detector. The fluxes of the four neutrino flavours at NOMAD are predicted with an uncertainty of about 8% for νμ and νe, 10% for ν̄μ, and 12% for ν̄e. The energy-dependent uncertainty achieved on the νe/νμ prediction needed for a νμ→νe oscillation search ranges from 4% to 7%, whereas the overall normalization uncertainty on this ratio is 4.2%.
We propose precise and fast-track reconstruction at hadron collider experiments, for use in online trigger decisions. We describe the features of fast-track (FTK), a highly parallel processor ...dedicated to the efficient execution of a fast-tracking algorithm. The hardware-dedicated structure optimizes speed and size; these parameters are evaluated for the ATLAS experiment. We discuss some applications of high-quality tracks available to the trigger logic at an early stage, by using the LHC environment as a benchmark. The most interesting application is online selection of b-quarks down to very low transverse momentum, providing interesting hadronic samples: examples are Z/sup 0/spl rarr//bb~, potentially useful for jet calibration, and multi-b final states for supersymmetric Higgs searches. The paper is generated from outside the ATLAS experiment and has not been discussed by the ATLAS collaboration.
A method to study light attenuation effects in wavelength shifting fibres Cavasinni, V; Del Prete, T; Flaminio, V ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
01/2004, Letnik:
517, Številka:
1
Journal Article
Recenzirano
The quality of wavelength shifting fibres depends on two basic parameters: the transparency of the core material, polystyrene, and the reflection coefficients at the fibre internal interfaces ...(core–clad and clad–clad in double-clad fibres). We have developed a model to parameterize these effects. The model has been applied to study the light attenuation in fibres used in the ATLAS hadronic calorimeter (TILE Calorimeter), as well as in the ones produced by several firms.
A PMT-Block test bench Adragna, P.; Antonaki, A.; Boudagov, I. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/2006, Letnik:
564, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The front-end electronics of the ATLAS hadronic calorimeter (Tile Cal) is housed in a unit, called
PMT-Block. The PMT-Block is a compact instrument comprising a light mixer, a PMT together with its ...divider and a
3-in-1 card, which provides shaping, amplification and integration for the signals. This instrument needs to be qualified before being assembled on the detector. A PMT-Block test bench has been developed for this purpose. This test bench is a system which allows fast, albeit accurate enough, measurements of the main properties of a complete PMT-Block. The system, both hardware and software, and the protocol used for the PMT-Blocks characterization are described in detail in this report. The results obtained in the test of about 10
000 PMT-Blocks needed for the instrumentation of the ATLAS (LHC-CERN) hadronic Tile Calorimeter are also reported.
A device to characterize optical fibres Bosi, F.; Burdin, S.; Cavasinni, V. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
06/2002, Letnik:
485, Številka:
3
Journal Article
Recenzirano
Odprti dostop
ATLAS is a general purpose experiment approved for the LHC collider at CERN. An important component of the detector is the central hadronic calorimeter; for its construction more than 600,000 Wave ...Length Shifting fibres (corresponding to a total length of
1120
km
) have been used. We have built and put into operation a dedicated instrument for the measurement of light yield and attenuation length over groups of 20 fibres at a time. The overall accuracy achieved in the measurement of light yield (attenuation length) is 1.5% (3%). We also report the results obtained using this method in the quality control of a large sample of fibres.
Testbeam studies of production modules of the ATLAS Tile Calorimeter Alexa, C.; Anderson, K.; Biscarat, C. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/2009, Letnik:
606, Številka:
3
Journal Article
Recenzirano
Odprti dostop
We report test beam studies of 11% of the production ATLAS Tile Calorimeter modules. The modules were equipped with production front-end electronics and all the calibration systems planned for the ...final detector. The studies used muon, electron and hadron beams ranging in energy from 3 to 350GeV.
Two independent studies showed that the light yield of the calorimeter was ∼70pe/GeV, exceeding the design goal by 40%. Electron beams provided a calibration of the modules at the electromagnetic energy scale. Over 200 calorimeter cells the variation of the response was 2.4%. The linearity with energy was also measured. Muon beams provided an intercalibration of the response of all calorimeter cells. The response to muons entering in the ATLAS projective geometry showed an RMS variation of 2.5% for 91 measurements over a range of rapidities and modules. The mean response to hadrons of fixed energy had an RMS variation of 1.4% for the modules and projective angles studied. The response to hadrons normalized to incident beam energy showed an 8% increase between 10 and 350GeV, fully consistent with expectations for a noncompensating calorimeter. The measured energy resolution for hadrons of σ/E=52.9%/E⊕5.7% was also consistent with expectations.
Other auxiliary studies were made of saturation recovery of the readout system, the time resolution of the calorimeter and the performance of the trigger signals from the calorimeter.
We present a search for neutrino induced events containing a single, exclusive photon using data from the NOMAD experiment at the CERN SPS where the average energy of the neutrino flux is ≃25 GeV. ...The search is motivated by an excess of electron-like events in the 200–475 MeV energy region as reported by the MiniBooNE experiment. In NOMAD, photons are identified via their conversion to e+e− in an active target embedded in a magnetic field. The background to the single photon signal is dominated by the asymmetric decay of neutral pions produced either in a coherent neutrino–nucleus interaction, or in a neutrino–nucleon neutral current deep inelastic scattering, or in an interaction occurring outside the fiducial volume. All three backgrounds are determined in situ using control data samples prior to opening the ‘signal-box’. In the signal region, we observe 155 events with a predicted background of 129.2±8.5±3.3. We interpret this as null evidence for excess of single photon events, and set a limit. Assuming that the hypothetical single photon has a momentum distribution similar to that of a photon from the coherent π0 decay, the measurement yields an upper limit on single photon events, <4.0×10−4 per νμ charged current event. Narrowing the search to events where the photon is approximately collinear with the incident neutrino, we observe 78 events with a predicted background of 76.6±4.9±1.9 yielding a more stringent upper limit, <1.6×10−4 per νμ charged current event.
We present a study of exclusive neutral pion production in neutrino–nucleus Neutral Current interactions using data from the NOMAD experiment at the CERN SPS. The data correspond to 1.44×106 ...muon-neutrino Charged Current interactions in the energy range 2.5⩽Eν⩽300 GeV. Neutrino events with only one visible π0 in the final state are expected to result from two Neutral Current processes: coherent π0 production, ν+A→ν+A+π0 and single π0 production in neutrino–nucleon scattering. The signature of coherent π0 production is an emergent π0 almost collinear with the incident neutrino while π0's produced in neutrino–nucleon deep inelastic scattering have larger transverse momenta. In this analysis all relevant backgrounds to the coherent π0 production signal are measured using data themselves. Having determined the backgrounds, and using the Rein–Sehgal model for the coherent π0 production to compute the detection efficiency, we obtain 4630±522(stat)±426(syst) corrected coherent-π0 events with Eπ0⩾0.5 GeV. We measure σ(νA→νAπ0)=72.6±8.1(stat)±6.9(syst)×10−40 cm2/nucleus. This is the most precise measurement of the coherent π0 production to date.
A description of the response of the NOMAD electromagnetic calorimeter to electrons and photons is discussed. In particular, the dependence of the two-dimensional shower shape on the angle and energy ...of the incident particle is parametrized by analytical functions. Some applications to the neutrino event reconstruction are also reported.
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