Search for gluinos and squarks using like-sign dileptons in pp macro collisions at square root of s = 1.8 TeV.
Phys Rev Lett 87:25 (2001) 251803
Abstract:
We present results of the first search for like-sign dilepton ( e(+/-)e(+/-), e(+/-)mu(+/-), mu(+/-)mu(+/-)) events associated with multijets and large missing energy using 106 pb(-1) of data in pp macro collisions at square root of s = 1.8 TeV collected during 1992-1995 by the CDF experiment. Finding no events that pass our selection, we examine pair production of gluinos (tilde g) and squarks (tilde q) in a constrained framework of the minimal supersymmetric standard model. At tan beta = 2 and mu = -800 GeV/c(2), we set 95% confidence level limits of M(tilde g)>221 GeV/c(2) for M(tilde g) approximately M(tilde q), and M(tilde q)>168 GeV/c(2) for M(tilde q)>>M(tilde g), both with small variation as a function of mu.Observation of diffractive J/ψ production at the Fermilab Tevatron
Physical Review Letters 87:24 (2001) 2418021-2418026
Abstract:
The first observation of diffractive J/ψ(→μ+μ-) production in p̄p collisions at s√=1.8 TeV was presented. Events were selected with a pair of muon candidates using a three-level dimuon trigger system. The dimuon mass distribution was fitted with a sum of a Gaussian and a linear function to evaluate the fraction of background events in the signal region. A value of 0.59±0.15 for the gluon fraction of the diffractive structure function of the proton was extracted.Search for quark-lepton compositeness and a heavy W′ Boson using the eν channel in pp̄ Collisions at √s = 1.8 TeV
Physical Review Letters 87:23 (2001) 2318031-2318036
Abstract:
A study on searches for quark-lepton compositeness and a heavy boson at high electron-neutrino transverse mass was presented. The data collected in pp̄ collisions at √s=1.8 TeV was used for the analysis. The data obtained is found to be consistent with the standard model (SM) predictions.A study of a combination of MICROMEGAS+ GEM chamber in Ar-CO2 gas
IEEE Nuclear Science Symposium and Medical Imaging Conference 1 (2001) 265-268
Abstract:
A MICROMEGAS is a micropatterned gaseous detector that has great potential in many applications including high energy physics and astronomy. The detector consists of a micromesh supported by thin pillars (50 μm) and the space between the micromesh and the anode plane defines an amplification gap. The detector has a high rate capability and good spatial resolution. The performance of the MICROMEGAS can be improved by a preamplification device like a GEM to factor the gas multiplication into two stages. With the added preamplication, it is possible to minimize spark rates in detecting heavily ionizing particles without sacrificing gas gain significantly. The additional gas gain provided by the GEM also allows the detector to operate in a clean gas mixture like Ar-CO2 The use of a clean gas mixture allows the device to be radiation hard.Evidence for the decay D0 → Κ+π-π+π-
Physical Review D 64:11 (2001)