Başar Şarer

PRE-EQUILIBRIUM EMISSION IN DIFFERENTIAL CROSS-SECTION CALCULATIONS AND ANALYSIS OF EXPERIMENTAL DATA FOR 232Th

In this study, neutron-emission spectra produced by (n,xn) reactions on nuclei 232Th have been calculated. Angle-integrated cross-sections in neutron induced reactions on targets 232Th have been calculated at the bombarding energies from 2 MeV to 18 MeV. We have investigated multiple pre-equilibrium matrix element constant from internal transition for 232Th(n,xn) neutron emission spectra. In the calculations, the geometry dependent hybrid model and the cascade exciton model including the effects of pre-equilibrium have been used. Pre-equilibrium direct effects have been examined by using full exciton model. In addition, we have described how multiple pre-equilibrium emissions can be included in the Feshbach–Kerman–Koonin (FKK) fully quantum-mechanical theory. By analyzing (n,xn) reaction on 232Th, with the incident energy from 2 MeV to 18 MeV, the importance of multiple pre-equilibrium emission can be seen clearly. All calculated results have been compared with experimental data. The obtained results have been discussed and compared with the available experimental data and found agreement with each other.

Investigation of the (n, p) reaction cross-sections of some nuclei in the rare-earth elements for an incident energy range of 8–24 MeV

In this study, the (n, p) reaction cross-sections of some target nuclei in the rare-earth elements have been investigated for an incident energy range of 8–24 MeV. In these calculations, the geometry-dependent hybrid model and the cascade exciton model including the effects of pre-equilibrium have been used. The full exciton model has also been used to investigate the pre-equilibrium direct effects. All calculated results have been compared with experimental data. In addition, the ratios of experimental (n, p) cross-sections to calculated cross-sections using empirical and semi-empirical formulae have been calculated.

Comparisons of the Calculations Using Different Codes Implemented in MCNPX Monte Carlo Transport Code for Accelerator Driven System Target

The MCNPX code offers options based on physics packages; the Bertini, ISABEL, INCL4 intra-nuclear models, and Dresner, ABLA evaporation-fission models and CEM2k cascade-exciton model. The study analyzes the main quantities determining ADS performance, such as neutron yield, neutron leakage spectra, and neutron and proton spectrain the target andin the beam window calculated by the MCNPX-2.5.0 Monte Carlo transport code, which is a combination of LAHET and MCNP codes. The results obtained by simulating different models, cited above and implemented in MCNPX are compared with each other.The investigated system is composed of a natural lead cylindrical target and stainless steel (HT9) beam window. Target has been optimized to produce maximum number of neutrons with a radius of 20 cm and 70 cm of height. Target is bombarded with a high intensity linear accelerator by a 1 GeV, 1 mA proton beam. The protons are assumed uniformly distributed across the beam of radius 3 cm, and entering the target through a hole of 5.3 cm radius. The proton beam has an outer radius of 5.3 cm and an inner radius 5.0 cm. The maximum of the neutron flux in the target is observed on the axis ~ 10 cm below the beam window, where the maximum difference between 7 different models is ~ 15 %. The total neutron leakage out of the of the target calculated with the Bertini/ABLA is 1.83×1017 n/s, and is about 14 % higher than the value calculated by the INCL4/Dresner (1.60×1017 n/s). Bertini/ABLA calculates top, bottom and side neutron leakage fractions as 20 %, 2.3 %, 77.6 % of the total leakage, respectively, whereas, they become 18.6 %, 2.3 %, 79.4 % with INCL4/Dresner combination.

The application of the IRSL dating technique to feldspars from Kayseri-Turkey ☆

The aim of this study is to test the suitability for luminescence dating of polymineral sediment samples taken from Kayseri, Turkey, an important area for both geologists and archaeologists. Feldspars isolated from samples were heated at different temperatures for 10 min to optimise the preheat temperature. The optimal pre-heat temperature was found to be 220°C for 10 min. The IRSL technique was applied using both single- and multiple-aliquot procedures. Although both of these methods gave comparable results, the age obtained using multiple-aliquot procedures was found to be more reliable than those obtained by other methods. The results obtained were in good agreement with those of geological interpretations.

Hızlandırıcı Güdümlü Sistemlerde Nötronik Hesaplamalar

Bir kritikalti (k<1) sistemde Pb hedef, He, Na, Pb, Hg, W, PbBi sogutucular ve uzun yari omurlu bir nukleer atik, 99Tc, kullanilarak 6 farkli Hizlandirici Gudumlu Sistem (HGS) tasarimi yapilmistir. 1 GeV enerji, 10 mA akim siddeti ve 3 cm yaricapina sahip proton demeti dogal kursun hedefe gonderilmistir. Bu enerji icin proton basina uretilen parcacik sayisi (cogaltma faktoru), notron aki dagilimlari, isinma (heating) ve atik donusum miktarlari hesaplanmistir. Sistem; 200 cm yukseklik, 200 cm yaricap ve 2 cm duvar kalinlikli paslanmaz celikten yapilmis silindir seklinde bir celik kap, merkezinde 80 cm yukseklik ve 15 cm yaricapli bir silindirik dogal kursun hedef ve silindirik atik cubuklarindan olusmustur. Uc boyutlu nukleonik hesaplamalar, MCNPX bilgisayar programi ve ENDF/B-VI nukleer veri kutuphanesi kullanilarak gerceklestirilmistir.

Radiative corrections of order α to superallowed Fermi β-decays

The outer radiative corrections of order α to superallowed Fermi β-decays (14O,26mAl,34Cl,42Sc,46V,50Mn and54Co) are calculated by applying an approximation to Fermi function. The results are compared to other studies.

Comparison of two- and one-component preequilibrium exciton model calculations for some neutron induced reactions

Two-component preequilibrium, used by Gupta, and analogously one-component exciton model descriptions are applied to neutron induced reactions such as46Ti(n,n′),46Ti(n,xp) and27Al(n,xp) at 14.6 MeV. This is the first complete calculation made by the two-component approach of Gupta. In order to obtain mean lives the time-integrated form of master equations is used.

Detour transitions in internal bremsstrahlung from204Tl

The contribution of detour transitions to the internal bremsstrahlung accompanying nuclear β-decay from204Tl was calculated. It is shown that detour transition is important for204Tl which is unique first forbidden case. The photon spectrum was calculated and compared with the experimental spectrum measured.