Isomeric Ratios 109m,gPd in the (γ, n) and (n, 2n) Reactions

The method of induced activity of the investigated cross-sections of excitation of isomeric states in the 110Pd(y,n)109m,gPd and 110Pd(n,2n)109m,gPd reactions in the energy range 12–35 MeV is studied. The experimental results are compared with those of calculations carried out using the software package TALYS-1.6.

Ground-state and isomeric-state cross-sections for 92Mo(n,α)89Zr and 95Mo(n,p)95Nb reactions in the 13–15 MeV energy region

The (n,α) and (n,p) cross-sections and their isomeric ratios (σ m /σ g ) were measured at 13–15 MeV for 92Mo and 95Mo by activation and off-line γ-ray spectrometry. The activated Mo samples combined with Al foils were used to obtain the cross-section values and the neutron flux, generated using the 3H(d,n)4He reaction. The cross-sections of the ground states were obtained using the metastable state absolute cross-sections and the residual nuclear decay rule. The excitation functions, total cross-sections, and isomeric ratios for the 92Mo(n,α)89m,gZr and 95Mo(n,p)95m,gNb reactions were calculated using the TALYS-1.95 software. 92Mo(n,α)89m + gZr and 95Mo(n,p)95m + gNb reaction excitation functions were obtained using the EMPIRE-3.2.3 package. These simulation results were compared with the corresponding experimental data and with the evaluated data from the ENDF/B-VIII.0, JEFF-3.3, CENDL-3, and ROSFOND libraries. Only partial agreements were observed.

ESTIMATION AND SOURCES OF POLYCYCLIC AROMATIC HYDROCARBONS (PAHs) IN DUST AT FUEL FILLING STATIONS IN THE TAMALE METROPOLIS, GHANA

The aim of the study was to identify and quantify the concentrations and potential sources of Polycyclic Aromatic Hydrocarbons (PAHs) present in dust particles at fuel filling stations in the Tamale Metropolis. Sixteen USEPA recognised PAHs were identified after samples were analysed and their potential sources identified using PAH isomeric ratios. Sample extraction was conducted using an Accelerated Solvent Extractor (ASE) and PAH levels in samples were further analysed using the GC-MS system. The total PAHs concentrations in the High-Vehicular Traffic Areas fuel filling stations ranged from 38.70 µg/kg to 1,423,280 µg/kg with an average concentration of 158,080 ± 102,650 µg/kg, while that of the Low-Vehicular Traffic Areas ranged from 305 µg/kg to 3,176,400 µg/kg with an average concentration of 370,220 ± 218,140 µg/kg. Amongst the 16 PAHs identified, Benzo(a)Anthracene had the highest concentration for both Traffic Areas. The average concentration of Benzo(a)Pyrene was 39,310 µg/kg and this was 200 times higher than that recorded from the US urban background soils. The PAH isomeric ratios indicated a strong influence from petroleum and combustion sources on PAH concentration in the fuel filling stations. It is therefore necessary that appropriate measures are taken with regards to pollution control and risk management at fuel filling stations. Keywords: Benzo(a)Anthracene, Benzo(a)Pyrene, Pyrene, Source Identification, Fuel Filling Stations

ISOMER RATIOS IN PHOTONUCLEAR REACTIONS WITH MULTIPLE NEUTRON EMISSION

The aim of this work is studying of gamma-quanta energy dependence of isomeric ratios in A(γ,xn)m,g(A − xn) reactions in energy range 35...100MeV , i.e. beyond Great Dipole Resonance (GDR) region. Experimental data were taken from international database EXFOR for a wide range of nuclear mases (55 < A < 181). Theoretical values of isomeric ratios were obtained using TALYS-1.8 code. Several models of level densities with both enabled and disabled pre-equilibrium mechanism were considered in our simulations. Obtained results let us to make conclusions about different mechanisms of photonuclear reactions on certain nuclei, energy dependence of their relative contribution.