Current state and prospects of detectors in the terahertz range. Part 2. Heterodyne detection of terahertz radiation

The paper discusses the problems associated with the development of technology for terahertz radiation detectors. The main physical phenomena and recent progress in various methods of detecting terahertz radiation (direct detection and heterodyne detection) are considered. Advantages and disadvantages of direct detection sensors and sensors with heterodyne detection are discussed. In part 1, a number of features of direct detection are considered and some types of terahertz direct detection detectors are described. Part 2 will describe heterodyne detection and continue to describe some types of modern photonic terahertz receivers.

Current state and prospects of detectors in the terahertz range Part 1. Direct detection of terahertz radiation

The paper discusses the problems associated with the development of technology for terahertz radiation detectors. The main physical phenomena and recent pro-gress in various methods of detecting terahertz radiation (direct detection and het-erodyne detection) are considered. Advantages and disadvantages of direct detec-tion sensors and sensors with heterodyne detection are discussed. In part 1, a number of features of direct detection are considered and some types of terahertz direct detection detectors are described. Part 2 will describe heterodyne detection and continue to describe some types of modern photonic terahertz receivers.

A Complete CDW Theory for the Single Ionization of Multielectronic Atoms by Bare Ion Impact

A complete form of the post version of the continuum distorted wave (CDW) theory is used to investigate the single ionization of multielectronic atoms by fast bare heavy ion beams. The influence of the non-ionized electrons on the dynamic evolution is included through a residual target potential considered as a non-Coulomb central potential through a GSZ parametric one. Divergences found in the transition amplitude containing the short-range part of the target potential are avoided by considering, in that term exclusively, an eikonal phase instead of the continuum factor as the initial channel distortion function. In this way, we achieve the inclusion of the interaction between the target active electron and the residual target, giving place to a more complete theory. The present analysis is supported by comparisons with existing experimental electron emission spectra and other distorted wave theories.

Долинно-орбитальное взаимодействие в германии, легированном донорами V группы: количественный анализ

In the framework of the envelope function approximation, the wave functions of electrons localized at shallow donors P, As, Sb in Ge are calculated taking into account the valley-orbit coupling caused by the donor short-range potential. It is proposed an approach that makes it possible to include inter-valley mixing in the equation for a multi-component envelope function. The calculation of the effects of the valley-orbit interaction was carried out according to the perturbation theory, while the "bare" single-valley functions were found using the Ritz method. The parameters of the short-range part of the potential and the coefficient of inter-valley mixing were found individually for each donor, making it possible to obtain the best agreement with the results of experimental measurements of the energies of the singlet and triplet states. The envelope functions of the 1s(A1) and 1s(T2) states are calculated. The parameters of the valley-orbit interaction are found for each donor. It is also shown how the functions of the excited 2s, 2p0, 2p±, 3p0 states should be modified in order to remain orthogonal to the singlet and triplet functions within the framework of a more rigorous multivalley model.

Unveiling the strong interaction among hadrons at the LHC

One of the key challenges for nuclear physics today is to understand from first principles the effective interaction between hadrons with different quark content. First successes have been achieved using techniques that solve the dynamics of quarks and gluons on discrete space-time lattices1,2. Experimentally, the dynamics of the strong interaction have been studied by scattering hadrons off each other. Such scattering experiments are difficult or impossible for unstable hadrons3–6 and so high-quality measurements exist only for hadrons containing up and down quarks7. Here we demonstrate that measuring correlations in the momentum space between hadron pairs8–12 produced in ultrarelativistic proton–proton collisions at the CERN Large Hadron Collider (LHC) provides a precise method with which to obtain the missing information on the interaction dynamics between any pair of unstable hadrons. Specifically, we discuss the case of the interaction of baryons containing strange quarks (hyperons). We demonstrate how, using precision measurements of proton–omega baryon correlations, the effect of the strong interaction for this hadron–hadron pair can be studied with precision similar to, and compared with, predictions from lattice calculations13,14. The large number of hyperons identified in proton–proton collisions at the LHC, together with accurate modelling15 of the small (approximately one femtometre) inter-particle distance and exact predictions for the correlation functions, enables a detailed determination of the short-range part of the nucleon-hyperon interaction.

Integration of An Information System to Suggest A Drl Model in Radiology Department at Azadi Hospital in Duhok–kurdistan Region, Iraq

Computer Tomography is a useful technique in diagnostic radiology. However, it emits high radiation doses which may cause harm to patients. For this, a quality management system, Diagnostic Reference Levels (DRL) is used in European countries. The aim of this study was to suggest a DRL system in Duhok Hospitals. Patient’s data (70 – 80) were collected from Azadi Hospital for three main protocols head, chest and abdomen. Only 15 patients had complete data for calculations for the three protocols. The DRL results were then compared with the ones reported in several European countries. For example, in the head protocol for the a CTDI value of 81, the results of the calculated DLP and ED values were 1504 and 3.16 respectively. These values were found to be much higher than the corresponding values reported in Italy 13.12 and 2.76 respectively. As a result, the DRL using 75th percentiles corresponding to these three dosimetric values were also high. Similar high results for the abdomen protocol were recorded, however, the results of the chest protocol showed to be within the average range. Part two of this work involved designing a Flow Chart based on an Information System to help running the CT scan procedure more effectively. Additionally, an extra repository system was added to this model to solve the short capacity issue in Duhok Hospitals.