27 research outputs found
Nuclear effects on J/{\psi} production in proton-nucleus collisions
The study of nuclear effects for J/{\psi} production in proton-nucleus
collisions is crucial for a correct interpretation of the J/{\psi} suppression
patterns experimentally observed in heavy-ion collisions. By means of three
representative sets of nuclear parton distribution, the energy loss effect in
the initial state and the nuclear absorption effect in the final state are
taken into account in the uniform framework of the Glauber model. A leading
order phenomenological analysis is performed on J/{\psi} production
cross-section ratios RW/Be(xF) for the E866 experimental data. The J/{\psi}
suppression is investigated quantitatively due to the different nuclear
effects. It is shown that the energy loss effect with resulting in the
suppression on RW/Be(xF) is more important than the nuclear effects on parton
distributions in high xF region. The E866 data in the small xF keep out the
nuclear gluon distribution with a large anti-shadowing effect. However, the new
HERA-B measurement is not in support of the anti-shadowing effect in the
nuclear gluon distribution. It is found that the J/{\psi}-nucleon inelastic
cross section {\sigma} J/{\psi} abs depends on the kinematical variable xF, and
increases as xF in the region xF > 0.2. 1 Introductio
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An ultra-wide passband (5-30µm) filter for FTIR studies of Photosystem II
This paper reports on the design and manufacture of an ultra-wide (5-30µm) infrared edge filter for use in FTIR studies of the low frequency vibrational modes of metallo-proteins. We present details of the spectral design and manufacture of such a filter which meets the demanding bandwidth and transparency requirements of the application, and spectra that present the new data possible with such a filter. A design model of the filter and the materials used in its construction has been developed capable of accurately predicting spectral performance at both 300K and at the reduced operating temperature at 200K. This design model is based on the optical and semiconductor properties of a multilayer filter containing PbTe (IV-VI) layer material in combination with the dielectric dispersion of ZnSe (II-VI) deposited on a CdTe (II-VI) substrate together with the use of BaF2 (II-VII) as an antireflection layer. Comparisons between the computed spectral performance of the model and spectral measurements from manufactured coatings over a wavelength range of 4-30µm and temperature range 300-200K are presented. Finally we present the results of the FTIR measurements of Photosystem II showing the improvement in signal to noise ratio of the measurement due to using the filter, together with a light induced FTIR difference spectrum of Photosystem II
Acoustic Monitoring of Plasma Arcs in Direct Current Electric Arc Furnaces
In this article, the extraction of features from acoustic signals generated by a 60-kW direct current electric arc furnace and the use of these features to infer the arc length of the plasma jets in the furnace were considered. A sensor capable of such measurements would be more robust to the unobservable fluctuations of the arc length and would, in principle, allow better control of smelting operations. The collected data comprised sets of five separate 10-second recordings of the acoustic signal, furnace current, and voltage, each at nominal arc lengths of 5, 15, and 25 mm. In the approach, time-frequency features initially were obtained through filter bank analysis of the signals. Reduction of the dimensionality of these filter bank features was then performed using a nonlinear subspace method called kernel Fisher discriminant analysis.Finally, kernel discriminant features were used to infer the arc length via a nearest neighborclassification model that associated three classes of arc lengths (5, 15, and 25 mm) with theircorresponding features. The results of the small number of experiments suggest that a significantstatistical relationship exists between the length of a plasma arc and its acoustic signal despitepotentially large variations in arc phenomena inside the furnace