Comparisons of the MINOS near and far detector readout systems at a test beam
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 609:2-3 (2009) 106-113
Abstract:
MINOS is a long baseline neutrino oscillation experiment that uses two detectors separated by 734 km. The readout systems used for the two detectors are different and have to be independently calibrated. To verify and make a direct comparison of the calibrated response of the two readout systems, test beam data were acquired using a smaller calibration detector. This detector was simultaneously instrumented with both readout systems and exposed to the CERN PS T7 test beam. Differences in the calibrated response of the two systems are shown to arise from differences in response non-linearity, photomultiplier tube crosstalk, and threshold effects at the few percent level. These differences are reproduced by the Monte Carlo (MC) simulation to better than 1% and a scheme that corrects for these differences by calibrating the MC to match the data in each detector separately is presented. The overall difference in calorimetric response between the two readout systems is shown to be consistent with zero to a precision of 1.3% in data and 0.3% in MC with no significant energy dependence. © 2009 Elsevier B.V.Precision measurement of the X(3872) mass in J/psi pi(+) pi(-) decays.
Phys Rev Lett 103:15 (2009) 152001
Abstract:
We present an analysis of the mass of the X(3872) reconstructed via its decay to J/psi pi(+)pi(-) using 2.4 fb(-1) of integrated luminosity from pp collisions at square root(s)=1.96 TeV, collected with the CDF II detector at the Fermilab Tevatron. The possible existence of two nearby mass states is investigated. Within the limits of our experimental resolution the data are consistent with a single state, and having no evidence for two states we set upper limits on the mass difference between two hypothetical states for different assumed ratios of contributions to the observed peak. For equal contributions, the 95% confidence level upper limit on the mass difference is 3.6 MeV/c(2). Under the single-state model the X(3872) mass is measured to be 3871.61+/-0.16(stat)+/-0.19(syst) MeV/c(2), which is the most precise determination to date.Publisher's Note: Search for hadronic decays of W and Z bosons in photon events in pp̄ collisions at s=1.96TeV
Physical Review D - Particles, Fields, Gravitation and Cosmology 80:7 (2009)
Observation of the Ωb- baryon and measurement of the properties of the Ξb- and Ωb- baryons
Physical Review D - Particles, Fields, Gravitation and Cosmology 80:7 (2009)
Abstract:
We report the observation of the bottom, doubly-strange baryon Ωb- through the decay chain Ωb-→J/ψΩ-, where J/ψ→μ+μ-, Ω-→ΛK-, and Λ→pπ-, using 4.2fb-1 of data from pp̄ collisions at s=1.96TeV, and recorded with the Collider Detector at Fermilab. A signal is observed whose probability of arising from a background fluctuation is 4.0×10-8, or 5.5 Gaussian standard deviations. The Ωb- mass is measured to be 6054.4±6. 8(stat)±0.9(syst)MeV/c2. The lifetime of the Ωb- baryon is measured to be 1.13-0.40+0.53(stat)±0.02(syst)ps. In addition, for the Ξb- baryon we measure a mass of 5790.9±2.6(stat)±0.8(syst)MeV/c2 and a lifetime of 1.56-0.25+0.27(stat)±0.02(syst)ps. Under the assumption that the Ξb- and Ωb- are produced with similar kinematic distributions to the Λb0 baryon, we find σ(Ξb-)B(Ξb-→J/ψΞ-) σ(Λb0)B(Λb0→J/ψΛ)=0.167-0.025+0.037(stat) ±0.012(syst) and σ(Ωb-)B(Ωb-→J/ψΩ-) σ(Λb0)B(Λb0→J/ψΛ)=0.045-0.012+0.017(stat) ±0.004(syst) for baryons produced with transverse momentum in the range of 6-20GeV/c. © 2009 The American Physical Society.Precision measurement of the X(3872) mass in J/ψπ+π- decays
Physical Review Letters 103:15 (2009)