Fermilab experiment E835 has measured the cross section for the reaction p̄p→e+e− at s=11.63, 12.43, 14.40 and 18.22 GeV2. From the analysis of the 66 observed events new high-precision measurements ...of the proton magnetic form factor are obtained.
CDF Run II silicon vertex detector annealing study Stancari, M.; Knoepfel, K.; Behari, S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2014, Letnik:
743
Journal Article
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Between Run II commissioning in early 2001 and the end of operations in September 2011, the Tevatron collider delivered 12fb−1 of pp¯ collisions at s=1.96TeV to the Collider Detector at Fermilab ...(CDF). During that time, the CDF silicon vertex detector was subject to radiation doses of up to 12Mrad. After the end of operations, the silicon detector was annealed for 24days at 18°C. In this paper, we present a measurement of the change in the bias currents for a subset of sensors during the annealing period. We also introduce a novel method for monitoring the depletion voltage throughout the annealing period. The observed bias current evolution can be characterized by a falling exponential term with time constant τI=17.88±0.36(stat.)±0.25(syst.) days. We observe an average decrease of (27±3)% in the depletion voltage, whose evolution can similarly be described by an exponential time constant of τV=6.21±0.21days. These results are consistent with the Hamburg model within the measurement uncertainties.
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The spin-exchange collision cross-section for hydrogen atoms has been measured for the first time in the low temperature range 40–100 K by using the polarized hydrogen gas target of the HERMES ...experiment at DESY (Hamburg, Germany). The results agree with a previous measurement in the overlapping temperature region 80–100 K, while seem to hint an increasing behaviour with temperature in the region 50–80 K.
We report on the decay to two photons of the χc0(13P0) charmonium resonance formed in p̄p interactions at Fermilab experiment E835. We have measured the product of branching ratios ...BR(χc0→p̄p)×BR(χc0→γγ)=(6.52±1.18(stat)+0.48−0.72(sys))×10−8. Using values from the 2002 PDG, this measurement leads to the partial width Γ(χc0→γγ)=2.9±0.9 keV.
A gas analyzer for the internal polarized target of the HERMES experiment Baumgarten, C; Braun, B; Contalbrigo, M ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/2003, Letnik:
508, Številka:
3
Journal Article
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A gas analyzer has been developed for the internal polarized target of the HERMES experiment at DESY in order to determine the relative amount of atomic and molecular hydrogen or deuterium in a gas ...sample. The precise quantitative knowledge of this ratio is crucial because the nucleons in atoms and molecules contribute differently to the average nuclear polarization of the target gas. A new calibration technique used to derive the relative sensitivity to atoms and molecules is presented. As an example, it is shown how the gas analyzer is used within the HERMES environment to divide the molecules in the gas sample into an unpolarized and a potentially polarized fraction.
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