A cost effective method employing polysulphone, nalidixic acid, 8-methoxypsoralen and phenothiazine as UV dosimeters is presented for evaluating the UV spectrum. The exposure measured by each dosimeter is a function of the source spectrum and the spectral response of the material. Each material has a different spectral response and records a different dose for the same exposure. A least squares...

The dip is a feature in the diffuse spectrum of UHE protons in energy range 1 × 10 − 4 × 10 eV, which is caused by electron-positron pair production on CMB photons. Calculated for power-law generation spectrum with index γg = 2.7, the shape of the dip is confirmed with high accuracy by data of Akeno AGASA, HiRes, Yakutsk and Fly’s Eye detectors. The predicted shape of the dip is robust: it is v...

The dip is a feature in the diffuse spectrum of UHE protons in energy range 1× 1018− 4× 10 eV, which is caused by electron-positron pair production on CMB photons. Calculated for power-law generation spectrum with index γg = 2.7, the shape of the dip is confirmed with high accuracy by data of Akeno AGASA, HiRes, Yakutsk and Fly’s Eye detectors. The predicted shape of the dip is robust: it is va...

This work reports on investigation of the sensitivity of a Fourier-transform spectrometer to noise sources based on Monte-Carlo simulation of measurement of a single spectrum. Flexibility of this approach permits easily to imitate various noise contaminations of the interferograms and to obtain statistically reliable results for widely varying noise characteristics. More specifically, we evalua...

We show that a dual-population unification scheme provides a successful paradigm with which to describe the evolution and beaming of all bright extragalactic radio sources. The paradigm consists of two intrinsic radio-source populations, based on the two distinct radio-galaxy morphologies of Fanaroff-Riley classes I and II. These represent the 'unbeamed' or 'side-on' parent populations of steep...

With the sophisticated radiation transport codes available today, solving discrete inverse problems using transport is possible. We examine an inverse source problem where the unknowns are the • source spatial distribution and • source energy spectrum. For a tractable problem, we assume that the following are given: • the geometric configuration of the system and • the material properties (that...

We present XMM-Newton observations of the AGN SDSS 1430-0011. The low S/N spectrum of this source obtained in a snap shot Chandra observation showed an unusually flat continuum. With the follow up XMM-Newton observations we find that the source spectrum is complex; it either has an ionized absorber or a partially covering absorber. The underlying power-law is in the normal range observed for AG...