We have processed large-area strip sensors on silicon wafers grown by the magnetic Czochralski (MCZ) method. The n-type MCZ silicon wafers manufactured by Okmetic Oyj have nominal resistivity of ...900Ωcm and oxygen concentration of less than 10ppma. The Photoconductive Decay (PCD) measurements, current–voltage measurements and capacitance–voltage measurements were made to characterise the samples. The leakage current of 3μA at 900V bias voltage was measured on the 32.5cm2 detector. Detector depletion took place at about 420V. According to PCD measurements, process induced contamination was effectively bound and neutralised by the oxygen present in Czochralski silicon. During the sample processing, the silicon resistivity increased in spite of the lack of specific donor-killing heat treatment.
We have processed pin-diodes on Czochralski silicon (Cz-Si), standard float zone silicon (Fz-Si), and diffusion oxygenated float zone silicon (DOF) and irradiated them with 10- and 20-MeV protons. ...Evolutions of depletion voltage and leakage current as a function of irradiation dose were measured. Space charge sign inversion (SCSI) was investigated by an annealing study and verified by transient current technique (TCT). Czochralski silicon was found to be significantly more radiation hard than the other materials.
We have processed full-size strip detectors on Czochralski grown silicon wafers with resistivity of about 1.2
k
Ω
cm. Wafers grown with Czochralski method intrinsically contain high concentrations of ...oxygen, and thus have potential for high radiation tolerance. Detectors and test diodes were irradiated with 10
MeV protons. The 1-MeV neutron equivalent irradiation doses were 1.6×10
14 and 8.5×10
13
cm
−2 for detectors, and up to 5.0×10
14
cm
−3 for test diodes. After irradiations, depletion voltages and leakage currents were measured. Czochralski silicon devices proved to be significantly more radiation hard than the reference devices made on traditional detector materials.
We processed pin-diodes on Czochralski silicon (Cz-Si), standard Float Zone silicon (Fz-Si) and oxygenated Fz-Si. The diodes were irradiated with 10, 20, and
30
MeV
protons. Depletion voltages and ...leakage currents were measured as a function of the irradiation dose. Additionally, the samples were characterized by TCT and DLTS methods. The high-resistivity Cz-Si was found to be more radiation hard than the other studied materials.
A search for new dielectron-mass resonances using data recorded by the CDF II detector and corresponding to an integrated luminosity of 5.7 fb(-1) is presented. No significant excess over the ...expected standard model prediction is observed. In this data set, an event with the highest dielectron mass ever observed (960 GeV/c(2)) was recorded. The results are interpreted in the Randall-Sundrum (RS) model. Combined with the 5.4 fb(-1) diphoton analysis, the RS-graviton lower-mass limit for the coupling k/M¯(Pl)=0.1 is 1058 GeV/c(2), making it the strongest limit to date.
We present the first measurement of polarization and CP-violating asymmetries in a B{sub s}{sup 0} decay into two light vector mesons, B{sub s}{sup 0}{yields}{phi}{phi}, and an improved determination ...of its branching ratio using 295 decays reconstructed in a data sample corresponding to 2.9 fb{sup -1} of integrated luminosity collected by the CDF experiment at the Fermilab Tevatron collider. The fraction of longitudinal polarization is determined to be f{sub L}=0.348{+-}0.041(stat){+-}0.021(syst), and the branching ratio B(B{sub s}{sup 0}{yields}{phi}{phi})=2.32{+-}0.18(stat){+-}0.82(syst)x10{sup -5}. Asymmetries of decay angle distributions sensitive to CP violation are measured to be A{sub u}=-0.007{+-}0.064(stat){+-}0.018(syst) and A{sub v}=-0.120{+-}0.064(stat){+-}0.016(syst).
We present a measurement of the top-quark mass using a sample of tt events in 5.7 fb{sup -1} of integrated luminosity from pp collisions at the Fermilab Tevatron with {radical}(s)=1.96 TeV and ...collected by the CDF II Detector. We select events having large missing transverse energy, and four, five, or six jets with at least one jet tagged as coming from a b quark, and reject events with identified charged leptons. This analysis considers events from the semileptonic tt decay channel, including events that contain tau leptons. The measurement is based on a multidimensional template method. We fit the data to signal templates of varying top-quark masses and background templates, and measure a top-quark mass of M{sub top}=172.32{+-}2.4(stat){+-}1.0(syst) GeV/c{sup 2}.
We present the results of a search for pair production of a heavy toplike (t') quark decaying to Wq final states using data corresponding to an integrated luminosity of 5.6 fb{sup -1} collected by ...the CDF II detector in pp collisions at {radical}(s)=1.96 TeV. We perform parallel searches for t'{yields}Wb and t'{yields}Wq (where q is a generic down-type quark) in events containing a lepton and four or more jets. By performing a fit to the two-dimensional distribution of total transverse energy versus reconstructed t{sup '} quark mass, we set upper limits on the t't' production cross section and exclude a standard model fourth-generation t' quark decaying to Wb (Wq) with mass below 358 (340) GeV/c{sup 2} at 95% C.L.
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