ar X iv : a st ro - p h / 06 07 09 4 v 1 6 J ul 2 00 6 Studies of systematic uncertainties in the estimation of the monocular aperture of the HiRes experiment
نویسندگان
چکیده
We have studied several sources of systematic uncertainty in calculating the aperture of the High Resolution Fly’s Eye experiment (HiRes) in monocular mode, primarily as they affect the HiRes-II site. The energy dependent aperture is determined with detailed Monte Carlo simulations of the air showers and the detector response. We have studied the effects of changes to the input energy spectrum and composition used in the simulation. A realistic shape of the input spectrum is used in our analysis in order to avoid biases in the aperture estimate due to the limited detector resolution. We have examined the effect of exchanging our input spectrum with a simple E−3 power law in the “ankle” region. Uncertainties in the input composition are shown to be significant for energies below ∼ 1018 eV for data from the HiRes-II detector. Another source of uncertainties is the choice of the hadronic interaction model in the air shower generator. We compare the aperture estimate for two different models: QGSJet01 and SIBYLL 2.1. We also describe the implications of employing an atmospheric database with hourly measurements of the aerosol component, instead of using an average as has been used in our previously published measurements of the monocular spectra.
منابع مشابه
ar X iv : a st ro - p h / 06 07 09 4 v 2 2 4 M ay 2 00 7 Studies of systematic uncertainties in the estimation of the monocular aperture of the HiRes experiment
We have studied several sources of systematic uncertainty in calculating the aperture of the High Resolution Fly’s Eye experiment (HiRes) in monocular mode, primarily as they affect the HiRes-II site. The energy dependent aperture is determined with detailed Monte Carlo simulations of the air showers and the detector response. We have studied the effects of changes to the input energy spectrum ...
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Current analyses of VLT/UVES quasar spectra disagree with the Keck/HIRES evidence for a varying fine-structure constant, α. To investigate this we introduce a simple method for calculating the minimum possible uncertainty on ∆α/α for a given quasar absorber. For many absorbers in Chand et al. (2004) and for the single-absorber constraint of Levshakov et al. (2006) the quoted uncertainties are s...
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