Detection of limited-energy α particles using CR-39 in laser-induced p −11B reaction

Due to the harsh radiation environment produced by strong laser plasma, most of the detectors based on semiconductors cannot perform well. So, it is important to develop new detecting techniques with higher detection thresholds and highly charged particle resolution for investigating nuclear fusion reactions in laser-plasma environments. The Columbia Resin No. 39 (CR-39) detector is mainly sensitive to ions and insensitive to the backgrounds, such as electrons and photons. The detector has been widely used to detect charged particles in laser-plasma environments. In this work, we used a potassium–ethanol–water (PEW) etching solution to reduce the proton sensitivity of CR-39, by raising the detection threshold for the research of laser-induced 11B(p, α)2α reaction. We calibrated the 3–5 MeV α particles in an etching condition of 60°C PEW-25 solution (17% KOH + 25%C2H5OH + 58%H2O) and compared them with the manufacturer’s recommended etching conditions of 6.25 N NaOH aqueous solution at 98°C in our laser-induced nuclear reaction experiment. The results indicate, with the PEW-25 solution, that CR-39 is more suitable to distinguish α tracks from the proton background in our experiment. We also present a method to estimate the minimum detection range of α energy on specific etching conditions in our experiment

Age Structure and Body Size of The Tibetan Toad (Bufo tibetanus) Populations from Two Different Altitudes in China

Knowledge about the altitudinal patterns in age and body size helps to highlight the evolution of life history parameters in animals. In this study, we investigated the demographic traits of the Tibetan toad (Bufo tibetanus) between populations from low and high altitude habitats (2650 vs 3930m) using skeletochronology. We found 1) the mean age and body size of females were significantly greater than those of males in either population; 2) both sexes of toads from the higher altitude tended to be significantly older in age and larger in body size; 3) a significant positive relationship between age and body size within each sex of the toad at both altitudes; 4) growth rates varied between the two populations, with the higher rate observed in the low-altitude population, and lower in the high-altitude population. Our results suggest that factors other than age can influence altitudinal patterns in body size, such as altitude-associated temperature. Future research should pay attention to these factors and evaluate their influences on the growth patterns of animals.Knowledge about the altitudinal patterns in age and body size helps to highlight the evolution of life history parameters in animals. In this study, we investigated the demographic traits of the Tibetan toad (Bufo tibetanus) between populations from low and high altitude habitats (2650 vs 3930m) using skeletochronology. We found 1) the mean age and body size of females were significantly greater than those of males in either population; 2) both sexes of toads from the higher altitude tended to be significantly older in age and larger in body size; 3) a significant positive relationship between age and body size within each sex of the toad at both altitudes; 4) growth rates varied between the two populations, with the higher rate observed in the low-altitude population, and lower in the high-altitude population. Our results suggest that factors other than age can influence altitudinal patterns in body size, such as altitude-associated temperature. Future research should pay attention to these factors and evaluate their influences on the growth patterns of animals