Studies of mono-crystalline CVD diamond pixel detectors Bugg, W.; Hollingsworth, M.; Spanier, S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
09/2011, Letnik:
650, Številka:
1
Journal Article
Recenzirano
The Pixel Luminosity Telescope (PLT) is a dedicated luminosity monitor, presently under construction, for the Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider (LHC). It measures ...the particle flux in several three layered pixel diamond detectors that are aligned precisely with respect to each other and the beam direction. At a lower rate it also performs particle track position measurements. The PLT's mono-crystalline CVD diamonds are bump-bonded to the same readout chip used in the silicon pixel system in CMS. Mono-crystalline diamond detectors have many attributes that make them desirable for use in charged particle tracking in radiation hostile environments such as the LHC. In order to further characterize the applicability of diamond technology to charged particle tracking we performed several tests with particle beams that included a measurement of the intrinsic spatial resolution with a high resolution beam telescope.
Separation of scintillation and Cherenkov light in an optical calorimeter Akchurin, N.; Atramentov, O.; Carrell, K. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
09/2005, Letnik:
550, Številka:
1
Journal Article
Recenzirano
Simultaneous measurement of the scintillation and the Cherenkov light produced in hadronic shower development makes it possible to eliminate the effects of fluctuations in the electromagnetic shower ...fraction, which dominate and spoil the performance of non-compensating calorimeters. In this paper, we report on a study to separate the light signal produced by an optical calorimeter into its scintillation and Cherenkov components. To this effect, we use differences in the time structure of these two signals, as well as differences in the angular distribution of these two types of light. Both methods give useful results, especially when the numbers of scintillation and Cherenkov photons are comparable.
The ab initio No-Core Shell Model (NCSM) adopts an intrinsic Hamiltonian for all nucleons in the nucleus. Realistic two-nucleon and tri-nucleon interactions are incorporated. From this Hamiltonian, ...an Hermitian effective Hamiltonian is derived for a finite basis space conserving all the symmetries of the initial Hamiltonian. The resulting finite sparse matrix problem is solved by diagonalization on parallel computers. Applications range from light nuclei to multiquark systems and, recently, to similar problems in quantum field theory. We present this approach with a sample of recent results.
Results from a beam test of a prototype PLT diamond pixel telescope Hall-Wilton, R.; Loos, R.; Ryjov, V. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2011, Letnik:
636, Številka:
1
Journal Article
Recenzirano
Odprti dostop
We describe results from a beam test of a telescope consisting of three planes of single-crystal, diamond pixel detectors. This telescope is a prototype for a small-angle luminosity monitor, the ...Pixel Luminosity Telescope (PLT), for CMS. We recorded the pixel addresses and pulse heights of all pixels over threshold as well as the fast-or signals from all three telescope planes. We present results on the telescope performance including occupancies, pulse heights, fast-or efficiencies and particle tracking. These results show that the PLT design meets all required specifications.
The ab initio No-Core Shell Model (NCSM) begins with an intrinsic Hamiltonian for all nucleons in the nucleus. Realistic two-nucleon and tri-nucleon interactions are incorporated such as those ...recently developed from effective-field theory and chiral perturbation theory. We then derive a finite basis-space dependent Hermitian effective Hamiltonian that conserves all the symmetries of the initial Hamiltonian. The resulting finite Hamiltonian matrix problem is solved by diagonalization on parallel computers. Applications range from light nuclei to multiquark systems and, recently, to quantum-field theory including systems with bosons. We present this approach with a sample of recent results.
High voltage system for the CMS forward calorimeter Akchurin, N.; Atramentov, O.; Dimitrov, L. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
03/2007, Letnik:
572, Številka:
2
Journal Article
Recenzirano
Odprti dostop
The power supply system developed for the photomultipliers (PMTs) of the forward calorimeter (HF) of the Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider is described. The 1728 ...PMTs of the HF are divided into 24 clusters of 72 with similar gain value. All of the PMTs within each cluster are powered by the same three high voltage (HV) power supplies, making a total of only 72 power supplies in the entire system. In this so-called parallel dynode voltage distribution, the three HV power supplies can be adjusted from 0 to −2000, −800, and −400V, respectively. All output voltages are floating to facilitate a single-point ground configuration. The system is computer controlled and integrated into the CMS detector slow control facility.
We report the results of a search for a heavy neutral gauge boson Z super(') decaying into the dielectron final state using data corresponding to an integrated luminosity of 5.4 fb super(-1) ...collected by the D0 experiment at the Fermilab Tevatron Collider. No significant excess above the standard model prediction is observed in the dielectron invariant-mass spectrum. We set inline image depending on the dielectron invariant mass. These cross section limits are used to determine lower mass limits for Z super(') bosons in a variety of models. For the sequential standard model Z super(') boson a lower mass limit of 1023 GeV is obtained.
We present a new measurement of the WZ-->l nu ll (l=e, mu ) cross section and limits on anomalous triple gauge couplings. Using 4.1 fb super(-1) of integrated luminosity of inline image collisions at ...inline image, we observe 34 WZ candidate events with an estimated background of 6.0+/-0.4 events. We measure the WZ production cross section to be inline image, in good agreement with the standard model prediction. We find no evidence for anomalous WWZ couplings and set 95% C.L. limits on the coupling parameters, -0.077< lambda sub(Z)<0.093 and -0.029< Delta Kappa sub(Z)<0.080 in the HISZ parameterization for a Lambda =2 TeV form factor scale. These are the best limits to date obtained from the direct measurement of the WWZ vertex.
We present a search for pair production of doubly-charged Higgs bosons in the processes qqbar to H++H-- decaying through H++/-- to tau tau, muon tau, muon muon. The search is performed in ppbar ...collisions at a center-of-mass energy of sqrt{s}=1.96 TeV using an integrated luminosity of 7.0 fb-1 collected by the D0 experiment at the Fermilab Tevatron Collider. The results are used to set 95% C.L. limits on the pair production cross section of doubly-charged Higgs bosons and on their mass for different H++/-- branching fractions. Models predicting different H++/-- decays are investigated. Assuming BR(H++ -> tau+ tau+)=1 yields an observed (expected) lower limit on the mass of a left-handed H++/-- boson of 128 (116) GeV and assuming BR(H++ -> mu+ tau+)=1 the corresponding limits are 144 (149) GeV. In a model with BR(H++ -> tau+ tau+)=BR(H++ -> mu+ tau+)=BR(H++ -> mu+ mu+)=1/3, we obtain M(H++(L) > 130 (138) GeV.
We present a measurement of the ratio of events with correlated t and tbar spins to the total number of ttbar events. This ratio f is evaluated using a matrix-element-based approach in events with a ...single lepton (electron or muon) and at least four jets. We analyze ppbar collisions data corresponding to an integrated luminosity of 5.3 fb^-1 collected with the D0 detector at the Fermilab Tevatron collider operating at a center of mass energy $\sqrt{s}=1.96$ TeV. Combining this result with a recent measurement of f in dilepton final states, we find f in agreement with the standard model. In addition, the combination provides evidence for the presence of spin correlation in ttbar events with a significance of more than three standard deviations.