R&D on novel sensor routing and test structure development Hoffmann, K.-H.; Auzinger, G.; Bergauer, T. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2011, Letnik:
628, Številka:
1
Journal Article
Recenzirano
The Central European Consortium designed and prototyped generic test structures (TS) in a R&D study to allow standard monitoring of the process quality of silicon sensors of any given vendor. ...Furthermore, some novel signal routing strategies for silicon sensors have been applied on the wafers to achieve an implementation of a pitch adapter directly in the sensor, either in the first metal layer or in a second additional metal routing layer. These improvements would allow to connect the readout chip directly to the sensor, omitting an additional pitch adapter. The on-sensor pitch adapter would be reflected by a substantial material budget saving which would be of special interest for the tracking detectors at the super-LHC.
After a first batch of improved TS was produced in 2007, a second batch of enhanced TS and additional sensors, with integrated pitch adapters, has been produced by the Institute of Electron Technology in Warsaw, Poland. Some improvements of the TS and the designs of the sensors will be shown. Afterwards a selection of measurements on TS and sensors will be discussed as well as a testbeam and its first results.
Optimising the strip geometry for very fine pitch silicon strip sensors Dragicevic, M.; Bergauer, T.; Dolezal, Z. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2010, Letnik:
617, Številka:
1
Journal Article
Recenzirano
Future collider experiments will require tracking detectors with more precise silicon sensors for improved track reconstruction precision and possibly with the ability to provide input to the first ...level trigger. One way to enhance the tracking performance is the minimization of the readout pitch. We investigated the performance of such fine pitch strip sensors using multigeometry testsensors with a fixed readout pitch of
50
μ
m
and a varying number of intermediate strips and different strip widths. Results from a testbeam with
120
GeV
/
c
pions are presented, suggesting the best geometry for optimal spatial resolution. Furthermore we studied the possibility to derive the incidence angle of a particle from the cluster width, which could be used as a tracking trigger on transverse momentum.
Measurements are reported of differential cross sections for the production of a W boson, which decays into a muon and a neutrino, in association with jets, as a function of several variables, ...including the transverse momenta ( ) and pseudorapidities of the four leading jets, the scalar sum of jet transverse momenta ( ), and the difference in azimuthal angle between the directions of each jet and the muon. The data sample of pp collisions at a centre-of-mass energy of 7 TeV was collected with the CMS detector at the LHC and corresponds to an integrated luminosity of 5.0 fb super(-1). The measured cross sections are compared to predictions from Monte Carlo generators, MadGraph + pythia and sherpa, and to next-to-leading-order calculations from BlackHat + sherpa. The differential cross sections are found to be in agreement with the predictions, apart from the distributions of the leading jets at high values, the distributions of the at high- and low jet multiplicity, and the distribution of the difference in azimuthal angle between the leading jet and the muon at low values.
A peaking structure in the J/ psi phi J/ psi phi mass spectrum near threshold is observed in B super( plus or minus ) arrow right J/ psi phi K super( plus or minus )B plus or minus arrow right J/ psi ...phi K plus or minus decays, produced in pp collisions at s=7 TeV collected with the CMS detector at the LHC. The data sample, selected on the basis of the dimuon decay mode of the J/ psi J/ psi , corresponds to an integrated luminosity of 5.2 fb super(-1). Fitting the structure to an S -wave relativistic Breit-Wigner lineshape above a three-body phase-space nonresonant component gives a signal statistical significance exceeding five standard deviations. The fitted mass and width values are m=4148.0 plus or minus 2.4(stat.) plus or minus 6.3(syst.)MeV and Gamma =28-11+15(stat.) plus or minus 19(syst.)MeV, respectively. Evidence for an additional peaking structure at higher J/ psi phi J/ psi phi mass is also reported.
(ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image).Dijet production has been measured in ... collisions at a nucleon-nucleon centre-of-mass energy of 5.02... A data sample ...corresponding to an integrated luminosity of 35 ... was collected using the Compact Muon Solenoid detector at the Large Hadron Collider. The dijet transverse momentum balance, azimuthal angle correlations, and pseudorapidity distributions are studied as a function of the transverse energy in the forward calorimeters (...). For ... collisions, the dijet transverse momentum ratio and the width of the distribution of dijet azimuthal angle difference are comparable to the same quantities obtained from a simulated ... reference and insensitive to ... In contrast, the mean value of the dijet pseudorapidity is found to change monotonically with increasing ..., indicating a correlation between the energy emitted at large pseudorapidity and the longitudinal motion of the dijet frame. The pseudorapidity distribution of the dijet system in minimum bias ... collisions is compared with next-to-leading-order perturbative QCD predictions obtained from both nucleon and nuclear parton distribution functions, and the data more closely match the latter.
(ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image).A measurement of W super(+)W super(-) production in pp collisions at ... is presented. The data were collected with the CMS ...detector at the LHC, and correspond to an integrated luminosity of 4.92 plus or minus 0.11 fb super(-1). The W super(+)W super(-) candidates consist of two oppositely charged leptons, electrons or muons, accompanied by large missing transverse energy. The W super(+)W super(-) production cross section is measured to be 52.4 plus or minus 2.0 (stat.) plus or minus 4.5 (syst.) plus or minus 1.2 (lum.) pb. This measurement is consistent with the standard model prediction of 47.0 plus or minus 2.0 pb at next-to-leading order. Stringent limits on the WW gamma and WWZ anomalous triple gauge-boson couplings are set.
Results are presented of a search for compositeness in electrons and muons using a data sample of pp collisions at a center-of-mass energy s = 7 TeV collected with the CMS detector at the LHC and ...corresponding to an integrated luminosity of 5.0 fb - 1 . Excited leptons (a a) are assumed to be produced via contact interactions in conjunction with a standard model lepton and to decay via a a a a gamma , yielding a final state with two energetic leptons and a photon. The number of events observed in data is consistent with that expected from the standard model. The 95% confidence upper limits for the cross section for the production and decay of excited electrons (muons), with masses ranging from 0.6 to 2 TeV, are 1.48 to 1.24 fb (1.31 to 1.11 fb). Excited leptons with masses below 1.9 TeV are excluded for the case where the contact interaction scale equals the excited lepton mass. The limits on the cross sections are the most stringent ones published to date.
An inclusive search for supersymmetric processes that produce final states with jets and missing transverse energy is performed in pp collisions at a centre-of-mass energy of 8 TeV. The data sample ...corresponds to an integrated luminosity of 11.7 fb super(-1) collected by the CMS experiment at the LHC. In this search, a dimensionless kinematic variable, alpha sub(T), is used to discriminate between events with genuine and misreconstructed missing transverse energy. The search is based on an examination of the number of reconstructed jets per event, the scalar sum of transverse energies of these jets, and the number of these jets identified as originating from bottom quarks. No significant excess of events over the standard model expectation is found. Exclusion limits are set in the parameter space of simplified models, with a special emphasis on both compressed-spectrum scenarios and direct or gluino-induced production of third-generation squarks. For the case of gluino-mediated squark production, gluino masses up to 950-1125 GeV are excluded depending on the assumed model. For the direct pair-production of squarks, masses up to 450 GeV are excluded for a single light first- or second-generation squark, increasing to 600 GeV for bottom squarks.
A measurement of the t t A= production cross section in pp collisions at s = 7 TeV is presented. The results are based on data corresponding to an integrated luminosity of 2.3 fb-1 collected by the ...CMS detector at the LHC. Selected events are required to have one isolated, high transverse momentum electron or muon, large missing transverse energy, and hadronic jets, at least one of which must be consistent with having originated from a b quark. The measured cross section is 158.1 +/- 2.1 (stat .) +/- 10.2 (syst .) +/- 3.5 (lum .) pb , in agreement with standard model predictions.
An updated search for heavy narrow resonances decaying to muon or electron pairs using the CMS detector is presented. Data samples from pp collisions at s = 7 TeV and 8 TeV at the LHC, with ...integrated luminosities of up to 5.3 and 4.1 fb - 1 , respectively, are combined. No evidence for a heavy narrow resonance is observed. The analysis of the combined data sets excludes, at 95% confidence level, a Sequential Standard Model Z SSM a2 resonance lighter than 2590 GeV, a superstring-inspired Z I a2 lighter than 2260 GeV, and KaluzaaKlein gravitons lighter than 2390 (2030) GeV, assuming that the coupling parameter k / M A= Pl is 0.10 (0.05). These are the most stringent limits to date.
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