Isotopic Production Cross Sections Research Articles

Benchmarking of FLUKA production cross sections of positron emission tomography isotopes for in-vivo range verification in hadron therapy

Protons and carbon ions have been extensively used for radiotherapy treatments, and in comparison to conventional radiotherapy, they allow a more conformal dose to the target tumor, especially in case of deep-seated tumors. However, the accuracy of hadron therapy treatments is affected by uncertainties in the particle range calculations. Several techniques are under development for in-vivo range verification, one of which consists on measuring the activity distributions of positron emitters, such as 10C, 11C and 15O, which are produced in the patient body during proton and carbon ion treatments. A comparison between measured and expected positron emitter activity distributions can provide information on the quality of the delivered treatment and accuracy of the particle range calculations. In this work the FLUKA production cross sections for 10C, 11C and 15O originated from proton and carbon ion beams in carbon and oxygen targets were compared with experimental data, at low and therapeutic energies.

Cross-section measurement in the reactions of 136Xe on proton, deuteron and carbon

The isotopic production cross sections for the reactions of 136Xe induced by proton, deuteron and carbon at 168 MeV/u were obtained by using the inverse kinematics technique at RIKEN Radioactive Isotope Beam Factory. The target dependence of the cross sections was investigated systematically. It was found that for the light-mass products, the cross sections on carbon are larger than those on deuteron and proton. The measured cross sections on proton were compared with the previous data at higher reaction energies to study the energy dependence. The experimental results were compared with the theoretical calculations including both the intranuclear cascade and evaporation processes using PHITS and with the EPAX and SPACS empirical parameterizations.

Measurement of PET isotope production cross sections for protons and carbon ions on carbon and oxygen targets for applications in particle therapy range verification

Measured cross sections for the production of the PET isotopes , and from carbon and oxygen targets induced by protons (40–220 ) and carbon ions (65–430 ) are presented. These data were obtained via activation measurements of irradiated graphite and beryllium oxide targets using a set of three scintillators coupled by a coincidence logic. The measured cross sections are relevant for the PET particle range verification method where accurate predictions of the emitter distribution produced by therapeutic beams in the patient tissue are required. The presented dataset is useful for validation and optimization of the nuclear reaction models within Monte Carlo transport codes. For protons the agreement of a radiation transport calculation using the measured cross sections with a thick target PET measurement is demonstrated.

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

As an alternative production route for the medically interesting 178mTa isotope production cross sections of alpha particle induced nuclear reaction of the natHf(α,x)178W–178mTa process was investigated. Activation method, stacked target technique, and high resolution off-line γ-ray spectrometry were applied. Excitation functions of the natHf(α,x)178W reaction and of several other side reactions were determined up to 51 MeV. Activation cross section data were determined for the following reactions: natHf(α,x)176,177,178W, natHf(α,x)175,176,177,178g,180g,182g,183Ta, and natHf(α,x)173,175,179m2,180m,181Hf. The measured experimental data were compared with the results of earlier experimental data and the results of TALYS nuclear reaction model code calculation tabulated in the TENDL-2017 data library. Experimental data are presented for the first time in the 40–50 MeV energy region. Thick target yields were calculated for elemental hafnium target using the fitted experimental cross section data.

Possible production of neutron-rich Md isotopes in multinucleon transfer reactions with Cf and Es targets

The possibilities for production of yet unknown neutron-rich isotopes $^{261--265}\mathrm{Md}$ are explored in the multinucleon transfer reactions with stable beams bombarding on Cf and Es targets. The production of a given isotope of neutron-rich Md is optimized by appropriate choices of projectile-target combinations and bombarding energies. The production cross sections of neutron-rich Md isotopes in the $0n$ and $1n$ evaporation channels of multinucleon transfer reactions are compared. The prospects for the use of radioactive beams in the production of new Md isotopes are discussed.

Measurement of the Production Cross Sections for Isotopes of Transfermium Elements in Complete Fusion Reactions with the Subsequent Evaporation of a Proton and Neutrons

Experiments aimed at synthesizing and investigating the features of radioactive decay of isotopes of superheavy elements (Z ≥ 110) have been conducted in the Flerov Laboratory of Nuclear Reactions at the Joint Institute for Nuclear Research. Complete fusion reactions of an accelerated beam of 48Ca ions with transactinide targets with the subsequent evaporation of several neutrons from excited compound nucleus are typically used in these experiments. “Exotic” reaction channels with the evaporation of protons and several neutrons may be used to produce more neutron-rich isotopes of superheavy elements. The production cross sections were measured in experiments at the SHELS separator for Db and Rf isotopes produced in xn and pxn channels of the 50Ti + 209Bi → 259Db* reaction. The ratio of cross sections σ(xn)/σ(pxn) was on the order of 100.

Role of breakup processes in deuteron-induced spallation reactions at 100–200 MeV/nucleon

Use of deuteron-induced spallation reactions at intermediate energies has recently been proposed for transmutation of several long-lived fission products (LLFPs). In the design study of a transmutation system using a deuteron primary beam, accurate cross section data of deuteron-induced reactions on the LLFPs are indispensable. Reliable model predictions play an important role in completing the necessary cross section data since currently available experimental data are very limited. Under the circumstances, we have been developing a code system dedicated for deuteron-induced reactions, which is called DEURACS. Aiming to predict the production cross sections of residual nuclei, the purpose of the present work is to clarify a role of deuteron breakup processes in deuteron-induced spallation reactions at intermediate energies. Isotopic production cross sections of residual nuclei in the deuteron-induced reactions on 93Zr and 107Pd at 100-200 MeV/nucleon are analyzed using DEURACS, in which the breakup processes are explicitly taken into account. The calculated cross sections are decomposed into individual components corresponding to the absorption of either neutron or proton in the incident deuteron, or the deuteron itself. The calculated cross sections reproduced the experimental data well over a wide mass number range of residual nuclei. From a component-by-component analysis, it was found that the components of nucleon absorption have the significant contributions to the production of residual nuclei. Consideration of the breakup processes is essential to predict the production cross sections of residual nuclei in deuteron-induced reactions. The framework of DEURACS is applicable to deuteron-induced spallation reactions at intermediate energies.

Current status and desired precision of the isotopic production cross sections relevant to astrophysics of cosmic rays: Li, Be, B, C, and N.

The precision of the current generation of cosmic-ray (CR) experiments, such as AMS-02, PAMELA, CALET, and ISS-CREAM, is now reaching ≈1-3% in a wide range in energy per nucleon from GeV/nucleon to multi-TeV/nucleon. Their correct interpretation could potentially lead to discoveries of new physics and subtle effects that were unthinkable just a decade ago. However, a major obstacle in doing so is the current uncertainty in the isotopic production cross sections that can be as high as 20-50% or even larger in some cases. While there is a recently reached consensus in the astrophysics community that new measurements of cross sections are desirable, no attempt to evaluate the importance of particular reaction channels and their required precision has been made yet. It is, however, clear that it is a huge work that requires an incremental approach. The goal of this study is to provide the ranking of the isotopic cross sections contributing to the production of the most astrophysically important CR Li, Be, B, C, and N species. In this paper, we (i) rank the reaction channels by their importance for a production of a particular isotope, (ii) provide comparisons plots between the models and data used, and (iii) evaluate a generic beam time necessary to reach a 3% precision in the production cross sections pertinent to the AMS-02 experiment. This first road map may become a starting point in the planning of new measurement campaigns that could be carried out in several nuclear and/or particle physics facilities around the world. A comprehensive evaluation of other isotopes Z ⩽ 30 will be a subject of follow-up studies.

Multinucleon transfer process in the reaction Gd160 + W186

The multinucleon transfer reaction $^{160}\mathrm{Gd}$ + $^{186}\mathrm{W}$ is investigated within the framework of the dinuclear system (DNS) model combining gemini code. The DNS + gemini model is improved by including deformation degree of freedom. The shell effects on charge equilibration are investigated. Because of shell closure $N=126$, the behavior of inverse charge equilibration is found, which results in remarkable effects on production of exotic nuclei around $N=126$. The incident energy effects on production cross sections are investigated. Interestingly, it is found that the production yields of actinide neutron-rich nuclei strongly depend on the incident energy. However, for producing heavy neutron-rich nuclei around $N=126$ the incident energy effects are weak, in which the slight decrease of yields with increasing incident energy comes from damping of shell effects. Also, the contour map of isotope production cross sections are calculated at different incident energies. We predict that several unknown heavy neutron-rich nuclei around $A=180$ can be produced with cross sections at the order of ${10}^{\ensuremath{-}6}$ to ${10}^{\ensuremath{-}4}$ mb.

Theoretical study on production of unknown neutron-deficient Fl280–283 and neutron-rich Fl290–292 isotopes by fusion reactions

We attempt to calculate the production cross sections of unknown $^{280--283}\mathrm{Fl}$ and $^{290--292}\mathrm{Fl}$ isotopes by using hot fusion reaction mechanism within the dinuclear system model. The production of unknown neutron-deficient Fl isotopes ($^{280--283}\mathrm{Fl}$) is studied in the reactions $^{44}\mathrm{Ca}+^{242}\mathrm{Pu}$ and $^{36}\mathrm{S}+^{249}\mathrm{Cf}$ with the maximum evaporation residue cross sections values 0.91 pb, 6.17 pb, 36.16 pb, and 2.02 pb, respectively. The use of neutron-rich radioactive beams $^{44}\mathrm{Ar}$ and $^{46}\mathrm{Ar}$ may help us produce new neutron-rich Fl isotopes via fusion reaction mechanism only if an extremely high beam intensity were to be achieved in the future. The maximum production cross sections of unknown neutron-rich isotopes ($^{290--292}\mathrm{Fl}$) in the reactions $^{46}\mathrm{Ar}+^{248}\mathrm{Cm}$ and $^{46}\mathrm{Ar}+^{250}\mathrm{Cm}$ are predicted to be 4.06 pb, 8.55 pb, and 3.35 pb, respectively. At present, reaction with radioactive ion beams is not a promising method to produce neutron-rich superheavy nuclei and other reaction mechanisms such as transfer reaction need to be developed.

Near-Barrier Proton Transfer in Reactions with 3He Nucleus

Calculations of production cross sections for isotopes 194Au in the 3He + 194Pt reaction and 45Ti in the 3He + 45Sc reaction are performed, based on the solution to a time-dependent Schrodinger equation in combination with calculations in the statistical model using the computational code of the NRV data base. The experimental differences in the near-barrier energy dependences of the isotope production cross sections in these reactions are explained by the difference between the proton and neutron shells of the target nuclei, and by the different evolutions of the probability density for protons of the projectile nucleus and neutrons of the target nuclei in collisions.

Effect of isospin diffusion on the production of neutron-rich nuclei in multinucleon transfer reactions

The isospin dissipation dynamics in multinucleon transfer reactions has been investigated within the dinuclear system model. Production cross sections of neutron-rich isotopes around projectile-like and target-like fragments are estimated in collisions of $^{58,64}\mathrm{Ni}+^{208}\mathrm{Pb}$ and $^{78,86,91}\mathrm{Kr}+^{198}\mathrm{Pt}$ near Coulomb barrier energies. The isospin diffusion in the nucleon transfer process is coupled to the dissipation of relative motion energy and angular momentum of colliding system. The available data of projectile-like fragments via multinucleon transfer reactions are nicely reproduced. It is found that the light projectile-like fragments are produced in the neutron-rich region because of the isospin equilibrium in two colliding nuclei. However, the heavy target-like fragments tend to be formed on the neutron-poor side above the $\ensuremath{\beta}$-stability line. The neutron-rich projectiles move the maximal yields of heavy nuclei to the neutron-rich domain and are available for producing the heavy exotic isotopes, in particular around the neutron shell closure of $N=126$.

Deep-inelastic multinucleon transfer processes in the O16+Al27 reaction

The reaction mechanism of deep-inelastic multinucleon transfer processes in the $^{16}$O+$^{27}$Al reaction at an incident $^{16}$O energy ($E_{\rm lab}=134$ MeV) substantially above the Coulomb barrier has been studied both experimentally and theoretically. Elastic-scattering angular distribution, total kinetic energy loss spectra and angular distributions for various transfer channels have been measured. The $Q$-value- and angle-integrated isotope production cross sections have been deduced. To obtain deeper insight into the underlying reaction mechanism, we have carried out a detailed analysis based on the time-dependent Hartree-Fock (TDHF) theory. A recently developed method, TDHF+GEMINI, has been applied to evaluate production cross sections for secondary products. From a comparison between the experimental and theoretical cross sections, we find that the theory qualitatively reproduces the experimental data. Significant effects of secondary light-particle emissions are demonstrated. Possible interplay between fusion-fission, deep-inelastic, multinucleon transfer and particle evaporation processes are discussed.

Production mechanism of new neutron-rich heavy nuclei in the [formula omitted] reaction

The multinucleon transfer reaction of Xe136+198Pt at Elab=7.98 MeV/nucleon is investigated by using the improved quantum molecular dynamics model. The quasielastic, deep-inelastic, and quasifission collision mechanisms are studied via analyzing the angular distributions of fragments and the energy dissipation processes during the collisions. The measured isotope production cross sections of projectile-like fragments are reasonably well reproduced by the calculation of the ImQMD model together with the GEMINI code. The isotope production cross sections for the target-like fragments and double differential cross sections of 199Pt, 203Pt, and 208Pt are calculated. It is shown that about 50 new neutron-rich heavy nuclei can be produced via deep-inelastic collision mechanism, where the production cross sections are from 10−3 to 10−6 mb. The corresponding emission angle and the kinetic energy for these new neutron-rich nuclei locate at 40∘–60∘ and 100–200 MeV, respectively.

Cosmogenic activation of materials

Experiments looking for rare events like the direct detection of dark matter particles, neutrino interactions or the nuclear double beta decay are operated deep underground to suppress the effect of cosmic rays. But, the production of radioactive isotopes in materials due to previous exposure to cosmic rays is a hazard when ultra-low background conditions are required. In this context, the generation of long-lived products by cosmic nucleons has been studied for many detector media and for other materials commonly used. Here, the main results obtained on the quantification of activation yields on the Earth’s surface will be summarized, considering both measurements and calculations following different approaches. The isotope production cross-sections and the cosmic ray spectrum are the two main ingredients when calculating this cosmogenic activation; the different alternatives for implementing them will be discussed. Activation that can take place deep underground mainly due to cosmic muons will be briefly commented too. Presently, the experimental results for the cosmogenic production of radioisotopes are scarce and discrepancies between different calculations are important in many cases, but the increasing interest on this background source which is becoming more and more relevant can help to change this situation.

Neutron transfer in the C13+Au197 reaction from gold isotope residuals

Residual gold nuclei were produced via neutron transfer at multiple energies using a 130-MeV $^{13}\mathrm{C}$ beam incident on a stacked-foil target consisting of alternating layers of $^{197}\mathrm{Au}$ and $^{27}\mathrm{Al}$. Production cross sections, over an energy range of 56 to 129 MeV, for seven gold isotopes and two gold isomers were determined through activation analysis. By using the Wilczy\ifmmode \acute{n}\else \'{n}\fi{}ski binary transfer model with a modified version of the recoil formula and a standard evaporation model, we were able to reproduce the isotopic production cross sections at high beam energy, with some disagreement at lower beam energies. This limiting angular momentum model does not predict the transfer of sufficient angular momentum to reproduce the observed isomeric populations.

Ranking and validation of spallation models for isotopic production cross sections of heavy residua

.The production cross sections of isotopically identified residual nuclei of spallation reactions induced by 136Xe projectiles at 500AMeV on hydrogen target were analyzed in a two-step model. The first stage of the reaction was described by the INCL4.6 model of an intranuclear cascade of nucleon-nucleon and pion-nucleon collisions whereas the second stage was analyzed by means of four different models; ABLA07, GEM2, GEMINI++ and SMM. The quality of the data description was judged quantitatively using two statistical deviation factors; the H-factor and the M-factor. It was found that the present analysis leads to a different ranking of models as compared to that obtained from the qualitative inspection of the data reproduction. The disagreement was caused by sensitivity of the deviation factors to large statistical errors present in some of the data. A new deviation factor, the A factor, was proposed, that is not sensitive to the statistical errors of the cross sections. The quantitative ranking of models performed using the A-factor agreed well with the qualitative analysis of the data. It was concluded that using the deviation factors weighted by statistical errors may lead to erroneous conclusions in the case when the data cover a large range of values. The quality of data reproduction by the theoretical models is discussed. Some systematic deviations of the theoretical predictions from the experimental results are observed.

Production of heavy neutron-rich nuclei with radioactive beams in multinucleon transfer reactions

The production mechanism of heavy neutron-rich nuclei is investigated by using the multinucleon transfer reactions of $$^{136,148}{\hbox {Xe}}+^{208}$$ Pb and $$^{238}{\hbox {U}}+^{208}$$ Pb in the framework of a dinuclear system model. The evaporation residual cross sections of target-like fragments are studied with the reaction system $$^{148}{\hbox {Xe}}+^{208}$$ Pb at near barrier energies. The results show that the final isotopic production cross sections in the neutron-deficient side are very sensitive to incident energy while it is not sensitive in the neutron-rich side. Comparing the isotopic production cross sections for the reactions of $$^{208}$$ Pb bombarded with stable and radioactive projectiles, we find that neutron-rich radioactive beams can significantly increase the production cross sections of heavy neutron-rich nuclei.

Production cross sections of 169Yb and Tm isotopes in deuteron-induced reactions on 169Tm

The excitation functions of deuteron-induced reactions on 169Tm were measured using the stacked-foil method and high resolution gamma-ray spectrometry. The production cross sections of a medical radionuclide 169Yb were investigated. The result was compared with the previous experiments and found to be in good agreement. In addition to 169Yb, the production cross sections of Tm isotopes, 170Tm, 168Tm and 167Tm, were measured. These results were compared with the TALYS calculations taken from the TENDL-2015 online data library.

Measurement of the delayed neutron characteristics in the interaction of relativistic protons with 238U nuclei

In present paper the method and set-up for measurements of the delayed neutron characteristics in the interaction of relativistic protons with heavy nuclei are described. On the basis of this method the time dependence of delayed neutron activity has been measured for the interaction of 238U sample with 1 GeV pulsed proton beam of the synchrocyclotron of the Petersburg Institute of Nuclear Physics, Gatchina. The measured data were analyzed in the framework of the 8-group precursor's model with a consistent set of half-lives. The obtained results on the relative abundances of delayed neutron precursors are compared with appropriate data from the fast neutron induced fission of 233U, systematics data developed for neutron induced fission and data calculated on the basis of the isotopic production cross sections obtained for the reaction products from the inverse kinematics measurements 238U(1 A GeV)+p.