Effect of Beam Dynamics Processes in the Low Energy Ring ThomX

As part of the R\&D for the 50 MeV ThomX Compton source project, we have studied the effect of several beam dynamics processes on the evolution of the beam in the ring. The processes studied include among others Compton scattering, intrabeam scattering, coherent synchrotron radiation. We have performed extensive simulations of a full injection/extraction cycle (400000 turns). We show how each of these processes degrades the flux of photons produced and how a feedback system contributes to recovering most of the flux.Comment: Submitted to IPAC'14, WEPRO00

Compton scattering of polarized electron beam

Compton scattering of polarized photon beam by polarized relativistic electron beam is considered in the report. The numerical comparison of Compton scattering intensity and polarization intensity has been carried out for different directions of initial photon and electron polarization. It was shown that the use of polarized beam leads to considerable increasing of Compton scattering intensity in the range of high photon energy for initial electron beam energy beginning from 5 GeV. The effect of initial polarization of photon and electron beams to final polarization of scattered photon beam was considered.Розглянуто комптонівське розсіяння фотонного пучка на поляризованому релятивістському електроні. Розглянуто диференційний перетин комптонівського розсіяння з урахуванням ефектів поляризації. Доведено, що застосування поляризованих пучків призводить до значного зросту спектральної інтенсивності фотонів, в області високих енергій для початкової енергії електронного пучка від 5 ГеВ. Розглянуто вплив поляризації початкових фотонів на поляризацію комптонівських фотонів.Рассматривается комптоновское рассеяние поляризованного фотонного пучка на поляризованном релятивистском электроне. Рассмотрено дифференциальное сечение комптоновского рассеяния с учетом эффектов поляризации. Было сделано сравнение для различных поляризаций. Показано, что применение поляризованных пучков приводит к значительному увеличению спектральной интенсивности фотонов, в области высоких энергий, для начальной энергии электронного пучка от 5 ГэВ. Рассмотрено влияние поляризации начальных фотонов на поляризацию комптоновских фотонов

Реформа децентралізації в Україні: поточний стан та перспективи розвитку

Decentralization is a process aimed at creating an effective structure of local self-government bodies with signs of openness and flexibility, which will help to strengthen representative decision-making systems at the community level. By empowering local communities to manage their own affairs, as well as deepening cooperation between central and local authorities, an efficient system of local self-government will allow them to respond more adequately to the needs and priorities of people of a community, thereby ensuring that the government is able to regulate a wide range of economic and social issues, for instance, the problem of poverty reduction, job creation, gender equality, and environmental protection. Moreover, the introduction of a full-fledged local self-government of the European model will enable the country to fully integrate into the European community. Therefore, the purpose of the article is to analyse the results, problems and consequences of the implementation of the decentralization reform in Ukraine. In the course of the research the essence of decentralization is defined; mechanisms that are used nowadays to increase the financial autonomy of local authorities are outlined. The influence of decentralization on the economic nature and socio-economic development of regions is grounded. The key advantages and disadvantages of budget decentralization in Ukraine in recent years have been revealed. The dynamics of creation of united territorial communities is analysed. The influence of quantitative changes in the basis of the calculation of taxes, fees and compulsory payments on the dynamics of changes in the nominal revenues of local budgets is revealed. The dependence of local budgets on the State Budget and insufficiency of the volume of own and fixed revenues for the implementation of self-governing and delegated powers were identified. The proposals aimed at increasing the efficiency of budgetary regulation in the process of implementing reforms, which will be considered when developing and using tools and methods for improving budgetary regulation, have been developed.Досліджено особливості бюджетної децентралізації як складової частини реформи, що нині триває в Україні. Розкрито теоретичні основи бюджетної децентралізації, її сутнісні характеристики, функції, принципи та вплив на соціально-економічний розвиток регіонів. З'ясовано цільову спрямованість децентралізації задля створення економічно стабільного та збалансованого розвитку України. Виявлено ключові переваги та недоліки бюджетної децентралізації в Україні за останні роки. Проаналізовано динаміку створення об'єднаних територіальних громад. Виявлено вплив кількісних змін бази нарахування податків, зборів та обов'язкових платежів на динаміку зміни номінальних доходів місцевих бюджетів. Встановлено залежність місцевих бюджетів від Державного бюджету та недостатність обсягу власних і закріплених доходів для виконання самоврядних та делегованих повноважень. Виділено основні проблемні питання, котрі потребують вирішення для реалізації наймасштабнішої реформи в Україні

A collimation system for ELI-NP Gamma Beam System - design and simulation of performance

The purpose of this study was to evaluate the performance and refine the design of the collimation system for the gamma radiation source (GBS) currently being realised at ELI-NP facility. The gamma beam, produced by inverse Compton scattering, will provide a tunable average energy in the range between 0.2 and 20 MeV, an energy bandwidth 0.5% and a flux of about 108 photons/s. As a result of the inverse Compton interaction, the energy of the emitted radiation is related to the emission angle, it is maximum in the backscattering direction and decreases as the angle increase [1,2]. Therefore, the required energy bandwidth can be obtained only by developing a specific collimation system of the gamma beam, i.e. filtering out the radiation emitted at larger angles. The angular acceptance of the collimation for ELI-NP-GBS must be continuously adjustable in a range from about 700 to 60 μrad, to obtain the required parameters in the entire energy range. The solution identified is a stack of adjustable slits, arranged with a relative rotation around the beam axis to obtain an hole with an approximately circular shape. In this contribution, the final collimation design and its performance evaluated by carrying out a series of detailed Geant4 simulations both of the high-energy and the low-energy beamline are presented

Two-colour X-gamma ray inverse Compton back-scattering source

We present a simple and new scheme for producing two-colour Thomson/Compton radiation with the possibility of controlling separately the polarization of the two different colours, based on the interaction of one single electron beam with two light pulses that can come from the same laser setup or from two different lasers and that collide with the electrons at different angle. One of the most interesting cases for medical applications is to provide two X-ray pulses across the iodine K-edge at 33.2 keV. The iodine is used as contrast medium in various imaging techniques and the availability of two spectral lines accross the K-edge allows one to produce subtraction images with a great increase in accuracy

Compensation of Non-Linear Bandwidth Broadening by Laser Chirping in Thomson Sources

A new laser chirping prescription is derived by means of the phase-stationary method for an inci- dent Gaussian laser pulse in conjunction with a Li enard-Wiechert calculation of the scattered radia- tion flux and spectral brilliance. This particularly efficient laser chirp has been obtained using the electric field of the laser and for electrons and radiation on axis. The frequency modulation is some- what reduced with respect to that proposed in the previous literature, allowing the application of this procedure to lasers with larger values of the parameter a0. Numerical calculations have been performed using mildly focused and narrow bandwidth laser pulses, confirming a larger efficiency of the chirp prescription here introduced. The chirp efficiency has been analysed as a function of the laser parameter and focusing. Published by AIP Publishing

Generation of primary photons through inverse Compton scattering using a Monte Carlo simulation code

Photon sources based on inverse Compton scattering, namely, the interaction between relativistic electrons and laser photons, are emerging as quasimonochromatic energy-tunable sources either as compact alternatives to synchrotron facilities for the production of low-energy (10–100 keV) x rays or to reach the 1–100 MeV photon energy range, which is inaccessible at synchrotrons. Different interaction layouts are possible for electron and laser beams, and several applications are being studied, ranging from fundamental research in nuclear physics to advanced x-ray imaging in the biomedical field, depending on the radiation energy range, intensity, and bandwidth. Regardless of the specific application, a reliable tool for the simulation of the radiation produced is essential for the design, the commissioning, and, subsequently, the study and optimization of this kind of source. Different computational tools have been developed for this task, based on both a purely analytical treatment and Monte Carlo simulation codes. Each of these tools has strengths and weaknesses. Here, we present a novel Monte Carlo code based on GEANT4 for the simulation of inverse Compton scattering in the linear regime. The code produces results in agreement with CAIN, one of the most used Monte Carlo tools, for a wide range of interaction conditions at a computational time reduced by 2 orders of magnitude. Furthermore, the developed tool can be easily embedded in a GEANT4 user application for the tracking of photons generated through inverse Compton scattering in a given experimental setup