This study aims to assess the artificial and natural radiation dose levels in certain districts of Kocaeli province within the Marmara region, 37 years after the Chernobyl nuclear accident, and evaluate the current status prior to potential nuclear leakage events from Zaporijya or other nuclear power plants. Radioactive concentrations of 232Th, 238U, 40K and 137Cs were determined using HPGe gamma spectrometry in 26 soil samples collected from the region of interest. The average concentrations were found to be 22.35 Bqkg−1 for 238U, 26.36 Bqkg−1 for 232Th, 368.34 Bqkg−1 for 40K, and 2.44 Bqkg−1 for 137Cs. Furthermore, the study revealed an absorbed dose rate of 41.73 nGyh−1, an annual effective dose equivalent of 51.18 µSvy−1, and an excess lifetime cancer risk of 0.00018.

A radiological baseline study was carried out by means of a computational analysis to evaluate the distribution of 226Ra, 232Th, 40K and 137Cs in samples of beach sand collected from the coastal areas of Antalya, Turkey. The results of the radiological risk assessment indicated that the calculated radiological risk for workers and tourists was below the level that could pose an endangerment to life or the safe operation. There was also no evidence of recent migration of 137Cs or other isotopes through precipitation, dust transport, or by indirect means such as sea currents.

Proton-rich nuclei are synthesized via photodisintegration and reverse reactions. To examine this mechanism and reproduce the observed p-nucleus abundances, it is crucial to know the reaction rates and thereby the reaction cross sections of many isotopes. Given that the number of experiments on the reactions in astrophysical energy regions is very rare, the reaction cross sections are determined by theoretical methods whose accuracy should be tested. In this study, given that ^121 Sb is a stable seed isotope located in the region of medium-mass p-nuclei, we investigated the cross sections and reaction rates of the ^121 Sb( α , γ ) ^125 I reaction using the TALYS computer code with 432 different combinations of input parameters (OMP, LDM, and SFM). The optimal model combinations were determined using the threshold logic unit method. The theoretical reaction cross-sectional results were compared with the experimental results reported in the literature. The reaction rates were determined using the two input parameter sets most compatible with the measurements, and they were compared with the reaction rate databases: STARLIB and REACLIB.

There are 35 proton-rich isotopes between 74Se and 196Hg that cannot be synthesized through neutron captures and β− decays (s- and r-processes). A third process is therefore required for the production of these nuclei, the so-called p-process. The abundance and the origin of the p-nuclei are still not fully understood even though significant experimental and theoretical efforts in astrophysical modeling have been expended in the last two decades. The experimental studies with the activation method to measure cross sections of the relevant reactions have some limitations: the reaction product must be radioactive, should have an appropriate half-life, and its decay should be followed by proper γ-radiations. If the cross section cannot be calculated with the radiation followed by the first beta decay of the product, it can be measured using the second beta decay as an alternative method. In this study, the method and candidate reactions for the cross-section measurements via the second beta decay of the reaction product using the activation method are discussed.

Background: The reaction rates used in gamma-process nucleosynthesis network calculations are mostly derived from theoretical, statistical model cross sections. Experimental data is scarce for charged particle reactions at astrophysical, low energies. Where experimental (alpha,gamma) data exists, it is often strongly overestimated by Hauser-Feshbach statistical model calculations. Further experimental alpha-capture cross sections in the intermediate and heavy mass region are necessary to test theoretical models and to gain understanding of heavy element nucleosynthesis in the astrophysical gamma process. Purpose: The aim of the present work is to measure the Sb-121(alpha,gamma) I-125, Sb-121(alpha, n) I-124, and Sb-123(alpha, n) I-126 reaction cross sections. These measurements are important tests of astrophysical reaction rate predictions and extend the experimental database required for an improved understanding of p-isotope production. Method: The alpha-induced reactions on natural and enriched antimony targets were investigated using the activation technique. The (alpha,gamma) cross sections of Sb-121 were measured and are reported for the first time. To determine the cross section of the Sb-121(alpha,gamma) I-125, Sb-121(alpha, n) I-124, and Sb-123(alpha, n) I-126 reactions, the yields of. rays following the beta decay of the reaction products were measured. For the measurement of the lowest cross sections, the characteristic x rays were counted with a low-energy photon spectrometer detector. Results: The cross section of the Sb-121(alpha,gamma) I-125, Sb-121(alpha, n) I-124, and Sb-123(alpha, n) I-126 reactions were measured with high precision in an energy range between 9.74 and 15.48 MeV, close to the astrophysically relevant energy window. The results are compared with the predictions of statistical model calculations. The (alpha, n) data show that the a widths are predicted well for these reactions. The (alpha,gamma) results are overestimated by the calculations but this is because of the applied neutron and gamma widths. Conclusions: Relevant for the astrophysical reaction rate is the alpha width used in the calculations. While for other reactions the alpha widths seem to have been overestimated and their energy dependence was not described well in the measured energy range, this is not the case for the reactions studied here. The result is consistent with the proposal that additional reaction channels, such as Coulomb excitation, may have led to the discrepancies found in other reactions.

It is crucial to measure reaction cross sections relevant to the astrophysical gamma process so that theoretical reaction rates can be tested and validated with experimental data. The total cross sections for the Er-162(p,gamma)Tm-163 and the Er-162(p,n)Tm-162 reactions have been measured by the activation method in center-of-mass energies from 3.973 to 8.944 MeV and from 5.962 to 8.944 MeV, respectively. The nucleus Er-162 is the heaviest p nuclide to be measured by the activation method using gamma-ray spectroscopy, so far. It is important to note that the energy range for the (p, gamma) reaction measurement covers a large fraction of the astrophysically relevant energy region between 2.71 and 5.34 MeV. The targets were prepared by evaporating 28.2% isotopically enriched (Er2O3)-Er-162 powder onto carbon backing foils, and bombarded with proton beams provided by the FN Tandem Accelerator at the University of Notre Dame. The reaction yields have been determined by the observed activity of produced radioactive isotopes, which was detected offline by a high-purity germanium detector. The results are presented and compared with calculations from two statistical model codes: NON-SMOKER and TALYS.

Elastic alpha scattering cross sections on the even-odd 115In nucleus have been measured at energies Elab. = 16.15 MeV and 19.50 MeV. The high precision experimental data are used to derive the parameters of a local a nucleus optical potential.

Cross sections of the 107Ag(α, γ)111In and 107Ag(α,n)110In reactions have been measured with the activation method at effective center-of-mass energies between 7.79 MeV and 12.00 MeV close to the astrophysical energy range. The irradiation and counting of the 107Ag targets was carried out at ATOMKI using the cyclotron accelerator and the low background counting facility, respectively. Cross section results are presented and compared with the predictions of Hauser-Feshbach statistical model calculations using the NON-SMOKER and TALYS-1.4 codes. In general, above 10 MeV, the model calculation are able to reproduce reasonably well the experimental data, but below 10 MeV, depending on some input parameters strong deviations are also found.

Alpha induced reactions on natural and enriched antimony targets were investigated via the activation technique in the energy range from 9.74 MeV to 15.48 MeV, close to the upper end of the Gamow window at a temperature of 3 GK relevant to the γ-process. The experiments were carried out at the Institute for Nuclear Research, the Hungarian Academy of Sciences (MTA Atomki). 121Sb(α,γ)125I, 121Sb(α,n)124I and 123Sb(α,n)126I reactions were measured using a HPGe detector. In this work, the 121Sb(α,n)124 cross section results and the comparison with the theoretical predictions (obtained with standard settings of the statistical model codes NON-SMOKER and TALYS) were presented.

Background: alpha-nucleus potentials play an essential role for the calculation of alpha-induced reaction cross sections at low energies in the statistical model... Purpose: The present work studies the total reaction cross section sigma_reac of alpha-induced reactions at low energies which can be determined from the elastic scattering angular distribution or from the sum over the cross sections of all open non-elastic channels. Method: Elastic and inelastic 64Zn(a,a)64Zn angular distributions were measured at two energies around the Coulomb barrier at 12.1 MeV and 16.1 MeV. Reaction cross sections of the (a,g), (a,n), and (a,p) reactions were measured at the same energies using the activation technique. The contributions of missing non-elastic channels were estimated from statistical model calculations. Results: The total reaction cross sections from elastic scattering and from the sum of the cross sections over all open non-elastic channels agree well within the uncertainties. This finding confirms the consistency of the experimental data. At the higher energy of 16.1 MeV, the predicted significant contribution of compound-inelastic scattering to the total reaction cross section is confirmed experimentally. As a by-product it is found that most recent global alpha-nucleus potentials are able to describe the reaction cross sections for 64Zn around the Coulomb barrier. Conclusions: Total reaction cross sections of alpha-induced reactions can be well determined from elastic scattering angular distributions. The present study proves experimentally that the total cross section from elastic scattering is identical to the sum of non-elastic reaction cross sections. Thus, the statistical model can reliably be used to distribute the total reaction cross section among the different open channels.

In order to determine the radioactivity level at Izmit Bay Marmara Sea, marine sediment samples were collected from five different locations. The radioactivity concentrations of naturally occurring U-238,Th-232 and K-40 isotopes and also that of an artificial isotope Cs-137 were measured by using gamma-ray spectroscopy. Preliminary results show that the radioactivity concentrations of (238)w and Th-232 isotopes are lower than the average worldwide values while the radioactivity concentrations of the 40K are higher than the average worldwide value. A small amount of Cs-137 contamination, which might be caused by the Chernobyl accident, was also detected.

Background: Astrophysical reaction rates, which are mostly derived from theoretical cross sections, are necessary input to nuclear reaction network simulations for studying the origin of p nuclei. Past experiments have found a considerable difference between theoretical and experimental cross sections in some cases, especially for (alpha,gamma) reactions at low energy. Therefore, it is important to experimentally test theoretical cross section predictions at low, astrophysically relevant energies.Purpose: The aim is to measure reaction cross sections of Ag-107(alpha,gamma)In-111 and Ag-107(alpha,gamma)In-110 at low energies in order to extend the experimental database for astrophysical reactions involving alpha particles towards lower mass numbers. Reaction rate predictions are very sensitive to the optical model parameters and this introduces a large uncertainty into theoretical rates involving alpha particles at low energy. We have also used Hauser-Feshbach statistical model calculations to study the origin of possible discrepancies between prediction and data.Method: An activation technique has been used to measure the reaction cross sections at effective center of mass energies between 7.79 MeV and 12.50 MeV. Isomeric and ground state cross sections of the (alpha,n) reaction were determined separately.Results: The measured cross sections were found to be lower than theoretical predictions for the (alpha,gamma) reaction. Varying the calculated averaged widths in the Hauser-Feshbach model, it became evident that the data for the (alpha,gamma) and (alpha,n) reactions can only be simultaneously reproduced when rescaling the ratio of gamma to neutron width and using an energy-dependent imaginary part in the optical alpha + Ag-107 potential.Conclusions: The new data extend the range of measured charged-particle cross sections for astrophysical applications to lower mass numbers and lower energies. The modifications in the model predictions required to reproduce the present data are fully consistent with what was found in previous investigations. Thus, our results confirm the previously suggested energy-dependent modification of the optical alpha+nucleus potential.

C. Yalçın, 2, ∗ Gy. Gyürky, T. Rauscher, 4 G. G. Kiss, † N. Özkan, R. T. Güray, Z. Halász, T. Szücs, ‡ Zs. Fülöp, J. Farkas, Z. Korkulu, and E. Somorjai Kocaeli University, Department of Physics, Umuttepe 41380, Kocaeli, Turkey Institute for Nuclear Research (MTA Atomki), H-4001 Debrecen, POB.51., Hungary Centre for Astrophysics Research, University of Hertfordshire, Hatfield AL10 9AB, United Kingdom Department of Physics, University of Basel, 4056 Basel, Switzerland (Dated: April 8, 2015)

The total cross sections for the $^{152}$Gd(p,$\gamma$)$^{153}$Tb and $^{152}$Gd(p,n)$^{152}$Tb reactions have been measured by the activation method at effective center-of-mass energies \mbox{$3.47 \leq E_\mathrm{c.m.}^\mathrm{eff}\leq 7.94$ MeV} and \mbox{$4.96 \leq E_\mathrm{c.m.}^\mathrm{eff} \leq 7.94$ MeV}, respectively. The targets were prepared by evaporation of 30.6\% isotopically enriched $^{152}$Gd oxide on aluminum backing foils, and bombarded with proton beams provided by a cyclotron accelerator. The cross sections were deduced from the observed $\gamma$-ray activity, which was detected off-line by a HPGe detector in a low background environment. The results are presented and compared with predictions of statistical model calculations. This comparison supports a modified optical proton+$^{152}$Gd potential suggested earlier.

In this work we present the experimental details and the results of the α scattering measurement on 64 Zn performed at the Atomki cyclotron, at energies close to the Coulomb barrier (12.08 MeV and 16.15 MeV).A comparison of the cross sections to different global α-nucleus potential predictions is also presented.Inelastic scattering cross sections leading to the first few excited states of 64 Zn were also determined.Total cross sections important for the statistical model are also derived and compared with the available experimental data.

The total cross sections for the $^{152}\mathrm{Gd}(p,\ensuremath{\gamma})^{153}\mathrm{Tb}$ and $^{152}\mathrm{Gd}(p,{n)}^{152}\mathrm{Tb}$ reactions have been measured by the activation method at effective center-of-mass energies $3.47\ensuremath{\le}{E}_{\mathrm{c}}.\mathrm{m}{.}^{\mathrm{eff}}\ensuremath{\le}7.94$ MeV and $4.96\ensuremath{\le}{E}_{\mathrm{c}}.\mathrm{m}{.}^{\mathrm{eff}}\ensuremath{\le}7.94$ MeV, respectively. The targets were prepared by evaporation of 30.6% isotopically enriched $^{152}\mathrm{Gd}$ oxide on aluminum backing foils, and bombarded with proton beams provided by a cyclotron accelerator. The cross sections were deduced from the observed $\ensuremath{\gamma}$-ray activity, which was detected off-line by an HPGe detector in a low background environment. The results are presented and compared with predictions of statistical model calculations. This comparison supports a modified optical proton+$^{152}\mathrm{Gd}$ potential suggested earlier.

A. Ornelas∗a,b, D. Galavizb, Gy. Gyürkya, G. Kissa, Zs. Fülöpa, E. Somorjaia, T. Szücsa,1, M.P. Takácsa,1, P. Mohra,c, R.T. Gürayd , Z. Korkulua,d , N. Özkand , C. Yalçınd aATOMKI, H-4001 Debrecen, POB. 51, Hungary bCentro de Física Nuclear, University of Lisbon, 1649-003 Lisbon, Portugal cDiakonie-Klinikum, D-74523 Schwäbisch Hall, Germany dKocaeli University, Department of Physics, TR-41380 Umuttepe, Kocaeli, Turkey 1current adress: Helmholtz-Zentrum Dresden-Rossendorf (HZDR), D-01328 Dresden, Germany

R. T. Güray, N. Özkan, C. Yalçın, T. Rauscher, 3 Gy. Gyürky, J. Farkas, Zs. Fülöp, Z. Halász, and E. Somorjai Department of Physics, Kocaeli University, Umuttepe 41380, Kocaeli, Turkey Centre for Astrophysics Research, School of Physics, Astronomy and Mathematics, University of Hertfordshire, Hatfield 9AL 10AB, United Kingdom Department of Physics, University of Basel, CH-4056 Basel, Switzerland MTA Institute for Nuclear Research (MTA Atomki), 4001 Debrecen, Hungary (Dated: June 6, 2021)

Background: The γ process in supernova explosions is thought to explain the origin of proton-rich isotopes between Se and Hg, the so-called p nuclei. The majority of the reaction rates for γ process reaction network studies have to be predicted in Hauser-Feshbach statistical model calculations using global optical potential parametrizations. While the nucleon + nucleus optical potential is fairly well known, for the α + nucleus optical potential several different parametrizations exist and large deviations are found between the predictions calculated using different parameter sets. Purpose: By the measurement of elastic α-scattering angular distributions at energies around the Coulomb barrier a comprehensive test for the different global α + nucleus optical potential parameter sets is provided. Methods: Between 20 ◦ and 175 ◦ complete elastic alpha scattering angular distributions were measured on the 113 In p nucleus with high precision at Ec.m. = 15.59 and 18.82 MeV. Results: The elastic scattering cross sections of the 113 In(α,α) 113 In reaction were measured for the first time at energies close to the astrophysically relevant energy region. The high precision experimental data were used to evaluate the predictions of the recent global and regional α + nucleus optical potentials. Parameters for a local α + nucleus optical potential were derived from the measured angular distributions. Conclusions: Predictions for the reaction cross sections of 113 In(α, γ ) 117 Sb and 113 In(α,n) 116 Sb at astrophysically relevant energies were given using the global and local optical potential parametrizations.