Measurement of the Photon Structure Function at High Q^2 at LEP
ArXiv hep-ex/0004005 (2000)
Extraction of the width of the W boson from measurements of σ(pp̄→W+X)×B(W→eν) and σ(pp̄→Z+X)×B(Z→ee) and their ratio
Physical Review D - Particles, Fields, Gravitation and Cosmology 61:7 (2000) 1-22
Abstract:
We report on measurements on inclusive cross sections times branching fractions into electrons for W and Z bosons produced in pp̄ collisions at s=1.8 TeV. From an integrated luminosity of 84.5 pb-1 recorded in 1994-1995 using the DØ detector at the Fermilab Tevatron, we determine σ(pp̄→W+X)×B(W→eν) = 2310±10(stat)±50(syst)±100(lum)pb and σ(pp̄→Z+X)×B(Z→ee)=221±3(stat)±4(syst) ±10(lum) pb. From these, we derive σ(pp̄→W+X)×B(W→eν)/σ(pp̄→Z+X) ×B(Z→ee)=10.43±0.15(stat) ±0.20(syst)±0.10(NLO), B(W→eν)=0.1044±0.0015(stat)±0.0020(syst)±0. 0017(theory)±0.0010(NLO), and Γ W=2.169±0.031(stat)±0.042(syst)±0.041(theory) ±0.022(NLO)GeV. We use the latter to set a 95% confidence level upper limit on the partial decay width of the W boson into nonstandard model final states, ΓWinv, of 0.213 GeV. Combining these results with those from the 1992-1993 data gives σ(pp̄→W+X) ×B(W→eν)/σ(pp̄→Z+X)×B(Z→ee)=10. 51±0.25,ΓW=2.152±0.066 GeV, and a 95% C.L. upper limit on ΓWinv of 0.191 GeV. Using a sample with a luminosity of 505 nb-1 taken at s=630 GeV, we measure σ(pp̄→W+X)×B(W→eν)=658±67 pb. ©2000 The American Physical Society.The NA48(1) LKr calorimeter readout electronics
IEEE T NUCL SCI 47:2 (2000) 136-141
Abstract:
The NA48 experiment at the CERN SPS accelerator is making a measurement of the direct CP violation parameter epsilon'/epsilon by comparing the four rates of decay of K-S and K-L into 2(pi)(0) and pi(+)pi(-). To reconstruct the decays into 2 pi(0) the information from the almost 13500 channels of a quasi-homogeneous liquid krypton electromagnetic calorimeter is used. The readout electronics of the calorimeter has been designed to provide a dynamic range from a few MeV to about 50 GeV energy deposition per cell, and to sustain a high rate of incident particles. The system is made by cold charge preamplifiers (working at 120 degrees K), low-noise fast shapers followed by digitizer electronics at 40 MHz sampling rate that employs a gain switching technique to expand the dynamic range, where the gain can be selected for each sample individually (i.e. every 25 ns). To reduce the amount of data collected the system contains a zero suppression circuit based on halo expansion.Differential production cross section of Z bosons as a function of transverse momentum at √s = 1.8 TeV
Physical Review Letters 84:13 (2000)
Abstract:
We present a measurement of the transverse momentum distribution of Z bosons produced in pp collisions at √s = 1.8 TeV from data collected by the D experiment at the Fermilab Tevatron Collider. We find good agreement between our results and current resummation calculations, and also use our data to extract nonperturbative parameters for a particular version of the resummation formalism. The resulting values are significantly more precise than obtained in previous determinations. © 2000 The American Physical Society.Isolated photon cross section in p p̄ collisions at √s = 1.8 TeV
Physical Review Letters 84:13 (2000)