The electron-to-nucleon ratio or electron fraction is a key parameter in many astrophysical studies. Its value is determined by weakinteraction rates that are based on theoretical calculations subject to several nuclear physics uncertainties. Consequently, it is important to have a model independent way of constraining the electron fraction value in different astrophysical environments. Here we...

A new calibration protocol, developed by the AAPM Task Group 51 (TG-51) to replace the TG-21 protocol, is based on an absorbed-dose to water standard and calibration factor (N(D,w)), while the TG-21 protocol is based on an exposure (or air-kerma) standard and calibration factor (N(x)). Because of differences between these standards and the two protocols, the results of clinical reference dosime...

The electron Linacs found wide industrial and medical applications. Industrial Linacs include systems for scanning and output electron beam to air with foil window. The critical analysis of electron Linacs for the treatment of materials (degradation of PTFE, curing of composites and others) and food safety is considered in this report. The kind of radiation technologies on the basis of electron...

Atomic absorption spectroscopy Atomic absorption spectroscopy (AAS) was developed in the early 1950’s by Alan Walsh. It works on the principle that certain elements absorb certain wavelengths, and this level of absorption is characteristic of each element. Also, electrons in atoms can only exist in particular energy levels, and when an electron moves to a higher energy level, electromagnetic ra...

Several high-frequency peaked BL Lac objects such as Mrk 501 are strong TeV emitters. However, a significant fraction of the TeV gamma rays emitted are likely to be absorbed in interactions with the diffuse IR background, yielding electron-positron pairs. Hence, the observed TeV spectrum must be steeper than the intrinsic one. Using the recently derived intrinsic γ-ray spectrum of Mrk 501 durin...

We use electric force microscopy (EFM) to study single nanocrystal photoionization in two classes of high-quality nanocrystals whose exciton luminescence quantum yields approach unity in solution. The CdSe/CdS/ZnS core/shell nanocrystals do not photoionize, while the CdSe/CdS nanocrystals do show substantial photoionization. This verifies the theoretical prediction that the ZnS shell confines t...

PBDTTPD is one of the best conjugated polymers for solar cell applications (up to 8.5% efficiency). We have investigated the dynamics of charge generation in the blend with fullerene (PCBM) and addressed highly relevant topics such as the role of bulk heterojunction structure, fullerene excitation, and excess energy. We show that there are multiple charge separation pathways. These include elec...