Background Subtraction Approach Research Articles

The atmospheric neutrino flavor ratio from a 3.9 fiducial kiloton-year exposure of Soudan 2

We report a measurement of the atmospheric neutrino flavor ratio, R, using a sample of quasi-elastic neutrino interactions occurring in an iron medium. The flavor ratio (tracks/showers) of atmospheric neutrinos in a 3.9 fiducial kiloton-year exposure of Soudan 2 is 0.64±0.11(stat.)±0.06(syst.) of that expected. Important aspects of our main analysis have been checked by carrying out two independent, alternative analyses; one is based upon automated scanning, the other uses a multivariate approach for background subtraction. Similar results are found by all three approaches.

Brightness‐independent Measurements of Gamma‐Ray Burst Durations

We demonstrate that a brightness bias exists in the third BATSE catalog duration measurements of cosmic gamma-ray bursts. This bias, caused by the fact that the outlying emission from bright bursts is easier to detect than from dim bursts, is sufficient to obscure a time-dilation factor of order 2. To avoid this problem, we construct brightness-independent measures of duration and apply them to a sample of long bursts containing no known brightness biases. We render all bursts to the same signal-to-noise ratio level, and thereby miss comparable amounts of temporal structure in both dim and bright bursts. We show that of two popular duration measures, T50 and T90, the former is to be preferred when the primary requirement is a comparison between bright and dim bursts. Our background subtraction approach involves the simultaneous examination of time profiles from all eight of the BATSE's large area detectors and all four energy channels, enabling us to identify appropriate background regions and to discriminate effectively between burst and nonburst emission. We report the first brightness-independent duration measurements over a continuous range of peak flux. These results indicate an increasing time-dilation factor with decreasing flux. We estimate that the energy dependence of the derived durations is relatively small. Under the cosmological hypothesis, a self-consistent treatment, including the corresponding energy correction implied by redshift, indicates that (1 + zdim)/(1 + zbrt) is ~2.

Practical peak area measurements in X‐ray photoelectron spectroscopy

AbstractAn assessment of the reliability of peak area measurements using the simple linear background subtraction approach has been made by comparing the results obtained by a number of workers from a set of simulated spectra mixing the Fe 2p peaks from Fe metal and Fe2O3. The simulated spectra are generated from Gaussian peaks with a step background similar to that of Shirley, but modified to reproduce the sloping background on the low kinetic energy side of the peak. The results show that systematic errors in the total area of the Fe 2p peak may be as great as 40% using the workers best estimate of the background line. An alternative approach involving the areas of both 2p3/2 and 2p1/2 peaks reduces this error to 17%.