INTRODUCTION Effect of low dose radiation on health is an important subject in the field of radiation protection. There are several places in the world where the level of natural radiation is much higher than in other areas. Epidemiological and cytogenetical studies on the people in such areas provide good information about the effect of low dose radiation on health. We performed the cytogeneti...

The observed cosmic microwave background (CMB) radiation provides strong evidence for the hot big bang. The success of pri-mordial nucleosynthesis calculations (see Sec. 16, " Big-bang nucle-osynthesis ") requires a cosmic background radiation (CBR) characterized by a temperature kT ∼ 1 MeV at a redshift of z ≃ 10 9. In their pioneering work, Gamow, Alpher, and Herman [1] realized this and pred...

There have been great and rapid progresses in the field of γ-ray bursts (denoted as GRBs) since BeppoSAX and other telescopes discovered their afterglows in 1997. Here, we will first give a brief review on the observational facts of GRBs and direct understanding from these facts, which lead to the standard fireball model. The dynamical evolution of the fireball is discussed, especially a generi...

In this work we reexamine the opacity of the cosmic background radiation to the propagation of extremely high energy cosmic rays. We use the continuous energy loss approximation to provide spectral modification factors for several hypothesized cosmic ray sources. Earlier problems with this approximation are resolved including the effects of resonances other than the ∆.

Twelve high schools in Japan (of which six are in Fukushima Prefecture), four in France, eight in Poland and two in Belarus cooperated in the measurement and comparison of individual external doses in 2014. In total 216 high-school students and teachers participated in the study. Each participant wore an electronic personal dosimeter 'D-shuttle' for two weeks, and kept a journal of his/her wher...

We report a new Fabry-Perot search for Hα emission from the intergalactic cloud HI 1225+01 in an attempt to measure the low redshift ionizing background radiation. We set a new 2σ upper limit on Hα emission of 8 mR (5 × 10 ergs cm s arcsec). Conversion of this limit to limits on the strength of

We bring together some known ingredients beyond the standard model physics that can explain the hot big bang model with the observed baryon asymmetry and also the fluctuations in the cosmic microwave background radiation with a minimal set of assumptions. We propose an interesting scenario where the inflaton energy density is dumped into an infinitely large extra dimension. Instead of the infla...

People living in the plateaus of Colorado or New Mexico receive about 1.5 mSv more per year than those living near sea level. The added dose from cosmic rays during a coast-to-coast round trip flight in a commercial airplane is about 0.03 mSv. Altitude plays a big role, but the largest source of background radiation comes from radon gas in our homes (about 2 mSv per year). Like other sources of...

We study primordial gravitational waves produced during inflation in quantum gravity at a Lifshitz point proposed by Horava. Assuming power-counting renormalizability, foliation-preserving diffeomorphism invariance, and the condition of detailed balance, we show that primordial gravitational waves are circularly polarized due to parity violation. The chirality of primordial gravitational waves ...

This paper presents the analysis, design, and characterization of the thirty gigahertz instrument receiver developed for the Q-U-I Joint Tenerife experiment. The receiver is aimed to obtain polarization data of the cosmic microwave background radiation from the sky, obtaining the Q, U, and I Stokes parameters of the incoming signal simultaneously. A comprehensive analysis of the theory behind t...