About creation of a techological tomograph using the ELIAS accelerator

Estimates were made for the possibility of creating a technological tomograph based on the registration of Compton scattering of photons through the use of the Van de Graaff accelerator (ELIAS) at NSC KIPT. The GEANT3 package was used to simulate the process of production of a sharply directed bremsstrahlung beam, to define the converter thickness, and to determine the angular distribution and energy spectrum of photons. The computation of counting rate for the tomograph’s detector has shown that for materials of a density up to 3 g/cm3 the counting rate can reach 2600 counts/sec, this being quite sufficient for tomographs of this type

Research of the work of technological compton scattering tomograph on the photon beam of the source ¹³⁷Cs

The results of the works, which have been carried out in NSC KIPT, on creation of a stationary technological Compton scattering tomograph are submitted. Modeling physical processes under program GEANT 3 is carried out, the design of a tomograph for a case of use is determined as a source of photons of the accelerator Van de Graaf on energy 3 MeV. Tests results of a tomograph work on a photon beam of the source ¹³⁷Cs are submitted.Представлено результати виконаних у ННЦ ХФТІ робіт по створенню стаціонарного технологічного комптонівського томографа. Проведено моделювання фізичних процесів по програмі GEANT 3, визначено конструкцію томографа для випадку використання як джерело фотонів прискорювача Ван де Граафа на енергію 3 МеВ. Представлено результати випробування роботи томографа на пучку фотонів джерела ¹³⁷Cs.Представлены разультаты выполненных в ННЦ ХФТИ работ по созданию стационарного технологического комптоновского томографа. Проведено моделирование физических процессов по программе GEANT 3, определена конструкция томографа для случая использования в качестве источника фотонов ускорителя Ван де Граафа на энергию 3 МэВ. Представлены результаты испытания работы томографа на пучке фотонов источника ¹³⁷Cs

Radiative Decay of a Long-Lived Particle and Big-Bang Nucleosynthesis

The effects of radiatively decaying, long-lived particles on big-bang nucleosynthesis (BBN) are discussed. If high-energy photons are emitted after BBN, they may change the abundances of the light elements through photodissociation processes, which may result in a significant discrepancy between the BBN theory and observation. We calculate the abundances of the light elements, including the effects of photodissociation induced by a radiatively decaying particle, but neglecting the hadronic branching ratio. Using these calculated abundances, we derive a constraint on such particles by comparing our theoretical results with observations. Taking into account the recent controversies regarding the observations of the light-element abundances, we derive constraints for various combinations of the measurements. We also discuss several models which predict such radiatively decaying particles, and we derive constraints on such models.Comment: Published version in Phys. Rev. D. Typos in figure captions correcte