Alpha-induced Reactions Research Articles

Production routes analysis of PET agent 72As from alpha and proton induced reaction using different level density models

This study evaluated the production routes of the medically essential radioisotope 72As from the stable isotopes of gallium, germanium, arsenic, and selenium, where four alpha-induced reactions: 69Ga(α, n)72As, 71Ga(α, 3n)72As, 70Ge(α, np)72As, and 72Ge(α, nt)72As and five proton-induced reactions: 72Ge(p, n)72As, 73Ge(p, 2n)72As, 74Ge(p, 3n)72As, 75As(p, nt)72As, and 74Se(p, 2np)72As are evaluated using three phenomenological and one microscopic nuclear level density models in different energy ranges. The investigation compares the calculated results based on the chosen models and the experimental data collected from the EXFOR data library. Statistical factors H, D, and R were also computed to determine the level density model with the best fit to the experimental data. Some level density parameters were adjusted to enrich the fits further, and integral yield vs energy was calculated using the best-fitted models.

Cross section measurement of the Sm144(α,n)Gd147 reaction for studying the α -nucleus optical potential at astrophysical energies

Nuclear reactions involving alpha particles play an important role in various astrophysical processes such as the gamma-process of heavy element nucleosynthesis. The poorly known low-energy alpha-nucleus optical (AOMP) potential is a key parameter to estimate the rates of these reactions. The AOMP can be tested by measuring the cross section of alpha-scattering as well as alpha-induced reactions. Low energy elastic alpha-scattering on 144Sm has recently been measured with high precision. The aim of the present work was to complement that work by measuring the (a,n) cross sections on 144Sm at low energies. The experimental data shall be used to constrain the AOMP. From this potential the 144Sm(a,g)148Gd reaction rate can be derived with reduced uncertainties. The 144Sm(a,n)147Gd reaction was studied by bombarding Sm targets with alpha-beams provided by the cyclotron accelerator of Atomki. The cross section was determined using the activation method. The gamma-radiation following the decay of the 147Gd reaction product was measured with a HPGe detector. The experimental data are analyzed within the statistical model. The cross section was measured in the alpha-energy range between 13 and 20 MeV in 1 MeV steps, i.e., from close above the (a,n) threshold. The results were compared with statistical model calculations using various approaches and parametrizations for the AOMP, and excellent agreement was obtained for two recent potentials. However, these potentials cannot reproduce literature data for the 144Sm(a,g)148Gd reaction with the same accuracy. Constraints for the AOMP were derived from an analysis of the new 144Sm(a,n)147Gd data and literature data for 144Sm(a,g)148Gd. These constraints enable a determination of the reaction rate of the 144Sm(a,g)148Gd reaction with significantly reduced uncertainties of less than a factor of two.

Effects of combining some theoretical models in the cross-section calculations of some alpha-induced reactions for natSb

In cases where it is not possible to obtain the cross-section values experimentally due to various factors, the importance of obtaining them with theoretical models has been explained in many studies available in the literature. In this context, the comparison of the cross-section values obtained by using the theoretical models with the experimental data will also be very beneficial for updating and developing these models. Existing studies, which also serve this purpose, have given inspiration to this study and it is aimed to examine the effects of the simultaneous use of the alpha optical model potentials and the level density models on the cross-section calculations for some alpha-particle-induced reactions on natural antimony. The effects of theoretical models on the cross-section calculations were investigated by comparing the obtained calculation results with the experimental data taken from the literature. The TALYS code, which is frequently preferred in the literature, was used in all calculations within the scope of this study. For the comparison of the calculated results with the experimental data, not only a visual analysis by graphing the outcomes, but also a mean-weighted-deviation calculation was used, and the findings were interpreted by accounting for both of them.

Configuration and impurity quantification of AmLi sources using radiography and gamma spectroscopy

This paper presents the non-destructive assay of two AmLi sources used for detector characterization and active interrogation at PNNL, identified as MRC-101 and MRC-103. First, a detailed description of the internal configuration of 2724-BT encapsulated MRC sources is established. X-ray radiographs of the AmLi sources are reported for the first time to verify the dimensions and orientation of the encapsulation. Notably, a density variation was observed as a contrast change across the height of the source cavities. Contrary to commonly made assumptions in literature, it is indirectly observed that the AmLi source/target material only occupies a portion of the source cavity. The intensity of the prompt gamma-rays resulting from the inelastic scatter of alpha particles on 7Li was used to calculate the mass ratios of LiH:AmO2. The gamma-ray spectra revealed the presence of numerous impurities in both source and target material (243Am, 237Np, 154Eu, 23Na, and 9Be). Neutron-gamma production ratios were applied to the intensity of the Doppler-broadened peaks from alpha-induced reactions with 7Li, 9Be, and 23Na to calculate neutron rates for both sources. A neutron/alpha production yield (derived in this work) was then related to the atomic concentration of these isotopes to find the approximate masses within each source. Ultimately, the AmLi source density was estimated with prompt gamma analysis based on partial source volumes as 0.45±0.08g∕cm3.

Anti-TNF alpha-induced immune-mediated skin adverse reactions resolved by switching to ustekinumab

Anti-TNF alpha-induced immune-mediated skin adverse reactions resolved by switching to ustekinumab

Production cross sections of ytterbium and thulium radioisotopes in alpha-induced nuclear reactions on natural erbium

Activation cross sections of alpha-induced reactions on natural erbium were measured using a 50.9-MeV alpha-beam at the RIKEN AVF cyclotron. Well-established methods for the measurements, the stacked-foil activation technique and gamma-ray spectrometry, were used. Production cross sections of 166,169Yb and 165,166,167,168,170,173Tm were determined. This is the first measurement of the cross sections of 166,170Tm. The integral yield of the medical radionuclide 169Yb was derived from the measured excitation function.

Excitation function measurement for zirconium-89 and niobium-90 production using alpha-induced reactions on yttrium-89

An experiment of α-induced reactions on yttrium-89 was performed to investigate the excitation functions of 89Zr and 90Nb, which are suitable for immuno-PET studies. The stacked-foil method, activation technique, and off-line γ-ray spectrometry were used for this investigation. The excitation functions of 92m,91m,89m,89gNb,88Zr, and 90m,88g,87m,87gY were also derived and compared with earlier experimental and the TENDL-2017 data. Good agreements with part of the previous studies were found.

Parametrization study for the estimation of light particles (p, d, 3He, α) induced total reaction cross sections of target mass greater than 9 within the energy range of 10–200 MeV

In this study, semi-empirical total reaction cross section relation has been suggested for proton, deuteron, 3He, alpha-induced reactions up to the projectile energy of 200 MeV. Fitting parameters have been listed for each light particle reaction. It is applicable for all target nuclei with mass number greater than 9, and all particle kinetic energies below 200 MeV. The present results have been compared with the experimental data available in literature and with the calculated values based on Talys 1.9 and Empire 3.2 codes. The results showed that the parametrized relation could calculate the total reaction cross sections as accurate as of different nuclear codes for light particles at the intermediate incident energies.

Activation cross sections of alpha-induced reactions on natural ytterbium up to 50 MeV

Activation cross sections of α-particle induced reactions on natYb were measured. The stacked foil technique, the activation method and the γ-ray spectrometry were used. The stacked target consisted of natYb and natTi foils was irradiated with a 51.0-MeV α beam at the RIKEN AVF cyclotron. The γ rays emitted from the irradiated foils were measured using a high-resolution HPGe detector. Production cross sections of 170,171,172,173,175Hf, 171,172,173,177gLu and 169Yb were determined. The results were compared with previous experimental studies and theoretical calculations. For most of the reactions a consistent agreement was found.

A new study on pre-equilibrium and equilibrium effects of excitation functions of alpha-induced reactions on 51V, 55Mn and 59Co nuclei

In this article, the cross section simulations of 51V(α,n)54Mn, 55Mn(α,n)58Co, 55Mn(α,2n)57Co, 59Co(α,2n)61Cu and 59Co(α,α2n)57Co nuclear reactions were carried out using the pre-equilibrium and equilibrium models. TALYS 1.9 and ALICE/ASH codes for the above nuclear reactions were used to describe the formation of the reaction process. Besides, the contribution on the cross section calculations of initial exciton number for alpha-induced reactions at the pre-equilibrium emissions is discussed. The results of this paper are compared with the measured nuclear data found in the literature. It was found that the initial exciton number n0 = 5 appears to give a good harmony to the measured values.

Activation cross sections of α-induced reactions on natZn for Ge and Ga production

The production cross sections of $^{68,69}$Ge and $^{66,67}$Ga by \alpha-induced reactions on $^{nat}$Zn have been measured using the stacked-foil activation method and off-line \gamma-ray spectrometry from their threshold energies to 50.7 MeV. The derived cross sections were compared with the previous experimental data and the calculated values in the TENLD-2017 library. Our result shows a slightly larger amplitude than the previous data at the peak, though the peak energy is consistent with them.

Activation cross sections of alpha-induced reactions on nat In for 117m Sn production

Abstract The production of 117mSn by charged-particle induced reactions is an interesting topic for medical application. Production cross sections of α-induced reactions on natIn for 117mSn up to 50 MeV were measured using the stacked foil technique and activation method. The integral yield of 117mSn was estimated using the measured cross sections. The results were compared with experimental data investigated earlier and theoretical calculation. Measured cross sections for 113Sn and 116m,117,118mSb isotopes were also presented.

Studies on excitation functions of alpha-induced reactions on natFe from threshold to 45 MeV

Excitation functions of the natFe(\( \alpha\), x)57Ni, natFe(\(\alpha\), x)55, 56, 57, 58m, gCo and natFe(\(\alpha\), x)52, 54Mn reactions were measured using the stacked-foil activation technique. The induced radioactivities in both the target and monitor foils were measured using an off-line \(\gamma\)-ray spectrometric technique. The cross sections for the above reactions were also calculated theoretically using the TALYS-1.8 code. The measured results were compared with the other experimental data and theoretical values. The theoretically calculated values are described well by our experimental data. It is observed that the rate of proton emission is larger than the neutron one. The measured results for the formation of few radionuclides are new and the other measured data strengthen the database. The experimental and theoretical studies on the investigated reactions should lead to a useful insight into the mechanisms of those reactions.

Alpha-induced reaction cross-section for Sm, U, Np targets: influence of hexadecapole deformation and deformed surface diffuseness

Alpha-induced reactions on 154Sm, 233,235,236,238U, and 237Np deformed nuclei are studied theoretically. The effects of hexadecapole deformation, deformed surface diffuseness parameter, and orientation on barrier height and position, fusion cross-section at any angle, and fusion cross-section have been investigated. Both hexadecapole deformation and deformed surface diffuseness can affect barrier characteristics and enhance fusion cross-section. Good agreement between experimental data and theoretical calculations with quadrupole and hexadecapole deformation and deformed surface diffuseness were observed for the 4He+154Sm, 235U, 237Np reactions.

Alpha-induced reactions on selenium between 11 and 15 MeV

The production of 77,79,85,85mKr and 77Br via the reaction Se() was investigated between and 15 MeV using the activation technique. The irradiation of natural selenium targets on aluminum backings was conducted at the Physikalisch-Technische Bundesanstalt (PTB) in Braunschweig, Germany. The spectroscopic analysis of the reaction products was performed using a high-purity germanium detector located at PTB and a low energy photon spectrometer detector at the Goethe University Frankfurt, Germany. Thick-target yields were determined. The corresponding energy-dependent production cross sections of 77,79,85,85mKr and 77Br were calculated from the thick-target yields. Good agreement between experimental data and theoretical predictions using the TALYS-1.6 code was found.

Study of the (p, γ) and (α, γ) reactions for 96,98,104Ru and 112,114,116Sn at astrophysically relevant energies

Cross section and S factor of the proton- and alpha-induced reactions have been studied for the Ruthenium and tin isotopes in the effective energy range, i.e. Gamow window. These reactions are important for developing the understanding for nucleosynthesis, particularly for the synthesis of p nuclei (p process). In this work, cross sections and S factor have been calculated through TALYS in Hauser–Feshbach formalism using nuclear densities calculated in relativistic mean field (RMF) formalism. Calculated results of cross sections, S factor and nuclear structure have been compared with existing theoretical as well as experimental results available and are found to be in good agreement.

Measurement of excitation functions of the natAg(α,x) reactions up to 45 MeV

We measured excitation functions for the production of the 108m,108g,109g,110m,110g,111gIn, the 109g,111mCd, and the 105g,106m,110m,111gAg in alpha-induced reactions on natAg in the energy range from their respective threshold to 45 MeV by using a stacked-foil activation and off-line γ-ray spectrometric technique. The present data were compared with the literature data and the theoretical values obtained from the TENDL-2015 library based on the TALYS-1.8 code. The integral yields for a thick target of the investigated radionuclides were also obtained from their measured cross sections and the stopping power. The measured excitation functions play important roles in various applications such as medical and industrial radioisotope production as well as for the improvement of nuclear model calculations.

α scattering and α -induced reaction cross sections of Zn64 at low energies

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.

Excitation function calculations for α + 93Nb nuclear reactions

In this study, the excitation functions of alpha-induced reactions on the 93Nb target nucleus were calculated by using ALICE-ASH code. The hybrid model, Weisskopf-Ewing model and geometry dependent hybrid model in this code were used to understand the alpha-niobium interaction. The contribution on the nuclear interaction of compound and pre-compound processes, with variation of the incident alpha particle energy, was presented. Furthermore, the reaction cross sections were calculated by using different level density models such as Superfluid nuclear model, Fermi gas model and Kataria-Ramamurthy Fermi gas model. Obtaining a good agreement between the calculated and the measured cross sections, the exciton numbers and the nuclear level density models were varied. Finally, the proper choice of the exciton numbers and the nuclear level density models was found to be quite important in order to obtain the more realistic cross section values.

Investigation of Alpha-Induced Reactions on 107Ag at Astrophysical Energies

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.