A theoretical study of excitation functions of isomers and isomeric cross section ratios in alpha induced reactions on Ag

A theoretical study based on statistical and pre-equilibrium calculations of the excitation functions and relevant isomeric cross-section ratios for the ¹⁰⁷Ag (α, n) ¹¹⁰In^m,g, ¹⁰⁷Ag (α, 3n) ¹⁰⁸In^m,g, ¹⁰⁹Ag (α, 3n) ¹¹⁰In^m,g, and ¹⁰⁷Ag (α, αn)¹⁰⁶Ag^m reactions have been carried out in the 10-40 MeV alpha energy range in a consistent way. The calculated excitation functions for the isomeric states, ground states and their ratios have been compared with reported measurements and TENDL-2010 and discussed.     

Nuclear model calculations on the production of Sb via various nuclear reactions

Only very few radionuclides exist that decay exclusively by EC-mode without accompanying radiation, ¹¹⁹Sb is one of them. Auger emitter ¹¹⁹Sb (T_1/2 = 38.9 h, I_EC = 100%) is a potent nuclide for targeted radionuclide therapy based on theoretical dosimetry calculations at a subcellular scale. Auger electron emitting radionuclides in cancer therapy offer the opportunity to deliver a high radiation dose to the tumor cells with high radiotoxicity while minimizing toxicity to normal tissue.     

Excitation functions of (n,p) reactions for stable isotopes of Cr,Fe and Ni from threshold to 20 MeV

The excitation functions of (n,p) reactions for the stable isotopes of Cr, Fe and Ni were calculated using EMPIRE 3.0 β1 (ARCOLE) from threshold to 20 MeV. The cross-sections are calculated using full featured Hauser–Feshbach statistical model with pre-equilibrium effects by invoking DEGAS option in the code. A good agreement between the calculated and experimental data (EXFOR data base) as well as evaluated data is obtained with option of neutron and proton potentials by Koning (Global) and HFB parity dependent nuclear level density. This is an important step to the validation of nuclear model with superior predictive power. The compound nucleus and pre-equilibrium reaction mechanisms as well as the isotopic effects were also studied.     

Activation cross sections of proton induced nuclear reactions on natural hafnium

In a systematic study of light charged particle induced nuclear reactions we investigated the excitation functions of proton induced reactions on natural hafnium targets. Experimental excitation functions of proton induced reactions up to 36 MeV on high purity natural hafnium were determined using the stacked foil activation technique. High resolution off-line gamma-ray spectrometry was applied to assess the activity of each foil. From the measured activity independent and/or cumulative elemental or isotopic cross section data for production of Ta, Hf and Lu radioisotopes were determined. The experimental data were compared to the data published earlier by other authors and to results of TALYS theoretical code taken from TENDL-2010 database. Thick target yields of the investigated radionuclides were calculated from the excitation function that was deduced as an analytical fit to our experimental cross section data points.     

Double differential cross sections of n + Cu reactions

The energy spectra and double differential cross sections of neutron, proton, deuteron, triton, helium and alpha-particle emissions for n + ^63,65,nat.Cu reactions are calculated and analyzed at incident neutron energies below 200 MeV. The optical model, the intra-nuclear cascade model, direct reaction theories, the unified Hauser–Feshbach and exciton model which includes the improved Iwamoto–Harada model are used. Theoretically calculated results are compared with the existing experimental data.     

Activation cross-sections of deuteron induced nuclear reactions on gold up to 40 MeV

Cross-sections of deuteron induced nuclear reactions on gold were measured up to 40 MeV by using the standard stacked foil irradiation technique and high resolution gamma-ray spectroscopy. Experimental cross-sections and derived integral yields are reported for the ¹⁹⁷Au(d,xn)^{197m,197g,195m,195g}Hg and ¹⁹⁷Au(d,x)^{198g,196m,196g,195,194}Au nuclear reactions. The experimental data are analyzed and compared to literature and predictions of the ALICE-IPPE, EMPIRE and TALYS theoretical model codes. The application of the new cross-sections for accelerator technology, medical radioisotope production, thin layer activation and dose calculation is discussed.     

Alpha induced reactions on Sn: An experimental study of excitation functions and possible production pathways

In the frame of a systematic study of light ion induced threshold reactions on natural tin (Sn) excitation functions for alpha particles induced reactions are presented in a 12–38 MeV energy domain. Using a stacked foil activation method the following radioisotopes were identified: ¹¹⁶Te, ¹¹⁷Te, ¹¹⁸Te, ¹¹⁹Te, ¹²¹Te, ¹²³Te, ¹¹⁷Sb, ¹¹⁸Sb, ¹²⁰Sb, ¹²²Sb, ¹²⁴Sb, ¹²⁶Sb, ¹¹⁷Sn, ¹¹¹In. The experimental cross sections for these isotopes are presented for the first time in this energy range and a direct comparison with values calculated with the ALICE-IPPE code is discussed. Possible use of these data for production of some isotopes relevant in nuclear medicine is suggested.     

Indirect measurement of inelastic cross section of relativistic protons in Pb target

The inelastic cross section of relativistic protons in Pb was determined indirectly by measuring the neutron distribution along a Lead spallation neutron source. The spallation neutron source was irradiated by 1, 1.5 and 2 GeV protons. The experimental results were obtained using passive methods. By the use of the beam attenuation coefficient, deduced by a fitting procedure of experimental data, the inelastic cross section of protons in Pb was determined.     

A critical survey of experimental cross section data, comparison with nuclear model calculations and estimation of production yields of Br and Kr in no-carrier-added form via various nuclear processes

Experimentally investigated nuclear reactions for production of no-carrier-added ⁷⁷Br and ⁷⁷Kr were critically surveyed. The survey covered nine reactions for the formation of ⁷⁷Br and six reactions for ⁷⁷Kr. Both radionuclides are simultaneously produced in many of the studied nuclear processes. The experimental data were compared with the results of nuclear model calculations based on the computer code ALICE-IPPE and the third version of TALYS-based Evaluated Nuclear Data Library, TENDL-2010. Good agreement was found over extended energy regions for the p-, ³He- and α-particle induced reactions on several target materials. In case of d-induced reactions, however, considerable discrepancies were noted between the experimental and theoretical data. The concordant sets of experimental cross section data for each reaction were fitted by a polynomial function to obtain a trend curve. From the thus obtained trend curves the yields of both ⁷⁷Br and ⁷⁷Kr were calculated. A discussion of suitable production routes is given.     

Theoretical cross sections of Bi,Th, U and U on deuteron-induced reactions

There are many application fields for fast neutrons. The main application fields of the fast neutrons are accelerator-driven sub-critical systems (ADS) and fusion–fission (hybrid) reactor systems for fission energy production. Thorium (Th) and uranium (U) are nuclear fuels in fusion–fission (hybrid) reactor systems and bismuth (Bi) is also the target nucleus in the ADS reactor systems. In this study, neutron production cross sections produced by (d, xn) reactions for spallation targets such as ²⁰⁹Bi, ²³²Th, ²³⁵U and ²³⁸U have been investigated. New evaluated hybrid model and geometry dependent hybrid model have been used to calculate the pre-equilibrium neutron production cross sections. For the reaction equilibrium component, Weisskopf–Ewing model calculations have been preferred. The obtained results have been discussed and compared with the available experimental data and found in agreement with each other.     

Calculation and evaluations for n+Cu reactions

All cross sections of neutron induced reactions, angular distributions, energy spectra and double differential cross sections are consistently calculated and analyzed for n+^63,65,nat.Cu reactions at incident neutron energies below 200 MeV based on the nuclear theoretical models. The optical model, preequilibrium and equilibrium reaction theories, the distorted wave Born approximation theory are used. Theoretical calculated results are compared with existing experimental data and the evaluated results in ENDF/B-VII and JENDL-3 libraries. The optical model potential parameters are obtained according to the experimental data of total, nonelastic scattering cross sections and elastic scattering angular distributions.     

Excitation functions of alpha-particle induced nuclear reactions on natural ytterbium

Excitation functions of the reactions ^natYb(α,xn)^{170,171,173,175,177m2}Hf, ^natYb(α,x)^{171g,172g,177g,178m}Lu and ^natYb(α,x)^169g,177gYb have been measured up to 39 MeV, among them seven (^{170,171,173,177m2}Hf, ^177g,178mLu, ^177gYb) are reported for the first time. The experimental excitation functions are compared to the theoretical calculations based on the model code ALICE-IPPE and to the only data-set found in the literature. Yields of different production routes of the therapeutically relevant ¹⁷⁷Lu are compared.     

Statistical significance of non-reproducibility of cross sectionsmeasured in dissipative reactions ^19F＋^93Nb

Two independent measurements of cross sections for the ^19F ^93Nb dissipative heavy-ion collision (DHIC) have been performed at incident energies from 100 to 108 MeV in steps of 250 keV. Two independently prepared targets were used respectively with all other experimental conditions being identical in both experiments. The data indicate non-reproducibility of the non-self-averaging oscillation yields in the two measurements. The statistical analysis of this non-reproducibility supports recent theoretical predictions of spontaneous coherence, slow phase randomization and extreme sensitivity in highly excited quantum many-body systems.     

239pu alpha spectrum analysis based on PIPS detector response function and variations with vacuum and distance

Effect factors of the absorption of the source,air,entrance window,and dead layer of a detector must be considered in the measurement of monoenergetic alpha particles,along with statistical noise and other factors that collectively cause the alpha spectrum to exhibit a well-known low-energy tail.Therefore,the estabUshment of an alpha spectrum detector response function from the perspective of a signaling system must consider the various factors mentioned above.The detector response function is the convolution of an alphaparticle pulse function,two exponential functions,and a Gaussian function,followed by calculation of the parameters of the detector response function using the weighted leastsquares fitting method as proposed in this paper.In our experiment,~(239)Pu alpha spectra were measured by a highresolution,passivated implanted planar silicon(PIPS)detector at 10 levels of vacuum and 10 source-detector distances.The spectrum-fitting results were excellent as evaluated by reduced Chi-square(x~2) and correlation coefficients.Finally,the variation of parameters with vacuum level and source-detector distance was studied.Results demonstrate that σ,τ_1,and τ_2 exhibit no obvious trend of variation with vacuum in the range 2000-20,000 mTorr,and at a confidence level of 95%,the values of τ_1 and τ_2 decline in a similar fashion with source-detector distance by the power exponential function,while the value of a declines linearly.     

Double differential cross sections of neutron and proton emission in neutron induced reactions on Fe

The energy spectra and double differential cross sections of neutron and proton emissions for n+^54,56,57,58Fe reactions are studied at incident neutron energies below 200 MeV based on the nuclear theoretical models, which are based on pre-equilibrium and equilibrium reaction theories. Theoretical calculated results are compared with existing experimental data.     

Differential cross section calculations of positron and electron impact ionization of Ar (3p)

We report the distorted wave Born approximation results of triple differential cross section of Ar (3p) by positron and electron impact. We compare the results of our calculations with the recent available experimental and theoretical results. We also provide a comparison of our positron impact ionization results with the electron impact ionization results to understand the effect of projectile charge on the projectile-target interaction.     

Double differential cross sections of light charged particle emission in neutron induced reactions on Fe

The energy spectra and double differential cross sections of the light composite particle (deuteron, triton, helium and alpha-particle) emissions for n + ^54,56,57,58Fe reaction are studied by integrating the optical model, the intra-nuclear cascade model, direct reaction theories, equilibrium reaction theory and the exciton model which included the improved Iwamoto–Harada model. Theoretical calculated results are compared with existing experimental data.     

Study of activation cross sections of proton induced reactions on erbium for practical applications

Excitation functions of the ^natEr(p,x)^{163,166,167,168,170}Tm and ^natEr(p,x)^cum161Er reactions were measured experimentally from the respective threshold up to 36 MeV incident proton energy and in the range of 60-70 MeV. The cross sections were measured with activation method using the stacked foil irradiation technique. A theoretical interpretation of contributing reactions based on results of the ALICE-IPPE code was done. From our experimental cross section data integral production yields were calculated which were compared to the experimental integral yield data reported in the literature.     

Evaluated activation cross sections of longer-lived radionuclides produced by deuteron induced reactions on natural titanium

Selected charged particle induced reactions are used to monitor the actual parameters of bombarding particle beams. One of these reactions is ^natTi(d, x)⁴⁸V for which recommended cross section data are available in one of the databases of the International Atomic Energy Agency (http://www-nds.iaea.or.at/medical/). This database contains all together 22 monitor reactions for practical applications covering energy up to 100 MeV depending on the reactions. In the case of the ^natTi(d, x)⁴⁸V reaction recommended data are given in the 9-50 MeV energy interval because at the time of creation not precise enough experimental data were available to recommend values from threshold up to 9 MeV. In this work we measured the excitation function in this relevant low energy range, collected new experimental data and suggest high confidence recommended values for the missing low energy part of the monitor excitation function.