Isotopic Production Cross Sections Research Articles

Production cross sections of new neutron-rich isotopes with Z=92–106 in the multinucleon transfer reaction Au197+Th232

The multinucleon transfer reactions $^{197}\mathrm{Au}+^{232}\mathrm{Th}, ^{186}\mathrm{W}+^{232}\mathrm{Th}$, and $^{238}\mathrm{U}+^{232}\mathrm{Th}$ are investigated within the framework of dinuclear system (DNS) model with a decay model gemini$++$. The calculated isotopic production cross sections in the $^{136}\mathrm{Xe}+^{249}\mathrm{Cf}$ reaction at ${E}_{\mathrm{c}.\mathrm{m}.}=567\phantom{\rule{0.28em}{0ex}}\mathrm{MeV}$ can reproduce the experimental data well. Due to the subshell closures, the behavior of ``inverse'' quasifission process is found in the collisions of $^{186}\mathrm{W}+^{232}\mathrm{Th}$ and $^{197}\mathrm{Au}+^{232}\mathrm{Th}$. The reaction $^{197}\mathrm{Au}+^{232}\mathrm{Th}$ is more advantageous to produce neutron-rich isotopes with $Z=92--106$ than $^{186}\mathrm{W}+^{232}\mathrm{Th}$ and $^{238}\mathrm{U}+^{232}\mathrm{Th}$, because it has the lowest value of the potential energy that needed to overcome in the nucleon transfer process. Furthermore, the incident energy dependence of isotopic production cross sections in the reaction $^{197}\mathrm{Au}+^{232}\mathrm{Th}$ is studied. It is found that ${E}_{\mathrm{c}.\mathrm{m}.}=756.47$ MeV is more suitable for producing new isotopes with $Z=92--98$, while ${E}_{\mathrm{c}.\mathrm{m}.}=690.69$ MeV is the optimal incident energy for $Z=99--106$. The effect of incident energy on the interaction time is also investigated. The production cross sections of 88 unknown neutron-rich transuranium nuclei are predicted with the cross sections at the order of ${10}^{\ensuremath{-}6}$ to $10\phantom{\rule{4pt}{0ex}}\ensuremath{\mu}\mathrm{b}$.

Multinucleon transfer mechanism inCf250+Th232collisions using the quantal transport description based on the stochastic mean-field approach

The production of elements close to the superheavy island of stability, with $Z>100$, is one of the most appealing challenges in nuclear physics. Based on a stochastic extension of the time-dependent Hartree-Fock theory, this article presents accurate microscopic calculations of multinucleon transfer for the ${}^{250}$Cf+${}^{232}$Th system at ${E}_{\mathrm{c}.\mathrm{m}.}=950$ MeV. Isotope production cross sections are described without any adjustable parameters, thus providing a benchmark to new experimental searches.

Production of unknown neutron-rich isotopes with Z=99–102 in multinucleon transfer reactions near the Coulomb barrier

Multinucleon transfer reactions provide a possible access to the synthesis of new neutron-rich isotopes. Within the theoretical framework of a hybrid model combining the dinuclear system model and the GRAZING model together, the transfer reaction is investigated in $^{86}\mathrm{Kr}+^{248}\mathrm{Cm}$. In this work, it is found that the hybrid model can reproduce experimental transfer cross sections well. After the verification of the hybrid model, the transfer reactions $^{112,124,132}\mathrm{Sn}+^{249}\mathrm{Cf}$ are investigated by the influence of charge equilibration on the production cross sections of the exotic nuclei. The neutron-deficient projectile $^{112}\mathrm{Sn}$ shows advantages of producing neutron-deficient nuclei, while $^{124,132}\mathrm{Sn}$ are favorable to produce neutron-rich nuclei. In order to obtain available production cross sections of the unknown neutron-rich isotopes with $Z=99\text{\ensuremath{-}}102$, the dependence of cross sections on incident energy in the reaction $^{132}\mathrm{Sn}+^{249}\mathrm{Cf}$ is also investigated. It is found that the reaction $^{132}\mathrm{Sn}+^{249}\mathrm{Cf}$ at 510 MeV is a potential candidate to produce unknown neutron-rich isotopes of trans-target.

Production of neutron-rich heavy nuclei around $$N = 162$$ in multinucleon transfer reactions

Within the framework of the dinuclear system model, the production mechanism of neutron-rich heavy nuclei around \(N = 162\) has been investigated systematically. The isotopic yields in the multinucleon transfer reaction of \(^{238}\)U + \(^{248}\)Cm are analyzed and compared with the available experimental data at GSI. Systematics on the production of superheavy nuclei via the collisions of \(^{238}\)U on actinide nuclides \(^{252,254}\)Cf, \(^{254}\)Es and \(^{257}\)Fm is investigated thoroughly. It is found that the shell effect is of importance in the formation of neutron-rich nuclei around \(N~=~162\) owing to the enhancement of fission barrier and neutron separation energy. The fragments in the multinucleon transfer reactions manifest the broad isotopic distribution and are dependent on the beam energy. The polar angles of the fragments tend to the forward emission with increasing the beam energy. The production cross sections of new isotopes are estimated and the heavier targets are available for the neutron-rich superheavy nucleus formation. The optimal reaction system and beam energy are proposed for the future experimental measurements.

Isotopic production cross sections of fragmentation residues produced by 18O ions on a carbon target near 260 MeV/nucleon* *Supported in part by the National Natural Science Foundation of China (11905260, 12005314), the Western Light Project of Chinese Academy of Sciences, the Heavy Ion Research Facility in Lanzhou (HIRFL), and the open research project of CAS large research infrastructures

The isotopic cross sections of residual nuclei produced in fragmentation reactions of 18O projectiles impinging on a carbon target at energies near 260 MeV/nucleon were measured at the HIRFL facility in Lanzhou (China). A full identification of atomic and mass numbers of fragments was achieved from the determination of their magnetic rigidity, energy loss, and time of flight. The production cross sections for a dozen of nitrogen, carbon, and boron isotopes were determined with uncertainties below 30% for most of the cases. The obtained cross sections for N and B isotopes show a rather good agreement with previous experimental data obtained with different projectile energies. The cross sections for some C isotopes seem to exhibit a dependence on the projectile energy. A comparison of the data and several theoretical model calculations are presented.

Theoretical study on the production of neutron-rich transuranium nuclei with radioactive beams in multinucleon transfer reactions

The production of neutron-rich transuranium nuclei with $Z=93--98$ in multinucleon transfer reactions induced by radioactive beams $^{92}\mathrm{Kr}, ^{132}\mathrm{Sn}$, and $^{144}\mathrm{Xe}$ with actinide target $^{238}\mathrm{U}$ is investigated within the dinuclear system model with decay code gemini$++$. The isotopic distributions for reactions $^{136}\mathrm{Xe}+^{248}\mathrm{Cm}$ and $^{136}\mathrm{Xe}+^{249}\mathrm{Cf}$ are calculated and compared with the available experimental data. Theoretical calculations can reproduce the experimental results well. Both the $N/Z$ ratio equilibration mechanism and driving potential dominate the transfer process of nucleons. Reaction $^{132}\mathrm{Sn}+^{238}\mathrm{U}$ is an optimal projectile-target combination to obtain large production cross sections of neutron-rich isotopes with $Z=93--98$. The corresponding optimal incident energy is also explored. The production cross sections of 41 unknown neutron-rich transuranium isotopes with cross sections greater than 1 nb are predicted. The reaction $^{132}\mathrm{Sn}+^{238}\mathrm{U}$ at ${E}_{\mathrm{c}.\mathrm{m}.}=521.3$ MeV shows huge advantages in producing neutron-rich transuranium nuclei with $Z=93--98$.

Reaction mechanism study for multinucleon transfer processes in collisions of spherical and deformed nuclei at energies near and above the Coulomb barrier: The O16+Sm154 reaction

Background: Multinucleon transfer reactions at energies around the Coulomb barrier offer a vital opportunity to study rich physics of nuclear structure and dynamics. Despite the continuous development in the field, we have still limited knowledge about how deformation - one of the representative nuclear structures - affects multinucleon transfer reactions. Purpose: To shed light on the effect of deformation in multinucleon transfer processes, we study the $^{16}$O+$^{154}$Sm reaction at $E_{\rm lab}$=85 MeV (around the Coulomb barrier) and 134 MeV (substantially above the Coulomb barrier), where the target nucleus, $^{154}$Sm, is a well-established, deformed nucleus. Results: Angular distributions for elastic scattering and for various transfer channels were measured over a wide angular range at the BARC-TIFR pelletron-Linac accelerator facility, Mumbai. The $Q$-value- and angle-integrated isotope production cross sections have been extracted from the measured angular distributions. The experimental data are analyzed along with time-dependent Hartree-Fock calculations. For the lower incident energy case, we find a reasonable agreement between the measurements and the TDHF calculations for a-few-nucleon transfer channels; whereas TDHF underestimates cross sections for many-nucleon transfers, consistent with earlier works. On the other side, we find that calculated cross sections for secondary reaction products for the higher incident energy case, qualitatively explains the measured trends of isotopic distributions observed for the lower energy. The latter observation indicates possible underestimation of excitation energies in the present TDHF+GEMINI analysis. Although certain orientation effects were observed in TDHF results, it is difficult to disentangle them from the $Q$-value- and angle-integrated production cross sections. (Shortened due to the arXiv's length limit.)

Production of unknown neutron-rich transuranium isotopes 245–249Np, 248–251Pu, 248–254Am, and 252–254Cm in multinucleon transfer reactions

The production cross sections of unknown neutron-rich transuranium isotopes of elements Np, Pu, Am and Cm are investigated in multinucleon transfer (MNT) reactions based on the dinuclear system model with GEMINI code. The influence of the incident energy on the production of neutron-rich transuranium nuclei in actinide–actinide collisions is studied. The calculation results show that the final isotopic production cross sections are larger at 1.06–1.10 V cont than at other energies. Considering the high fissility of transuranium nuclides, 1.06 V cont is chosen as the optimal incident energy. The N/Z ratio equilibration mechanism in the nucleon transfer process is also studied in this work. The larger difference of N/Z ratio between projectile and target corresponds to larger neutron diffusion during the nucleon exchange process. The 238U beam with high N/Z ratio and neutron-rich actinide targets are good selections to produce neutron-rich transuranium nuclides. The production cross sections of unknown neutron-rich transuranium isotopes 245–249Np, 248–251Pu, 248–254Am, and 252–254Cm are predicted in 238U-induced actinide-based (249Bk, 249Cf, and 252Cf) MNT reactions. It is found that a large number of these unknown neutron-rich transuranium nuclei could be generated at the level of nb to μb in the reactions 238U + 249Bk and 238U + 252Cf. Our research indicates that the reaction 238U + 249Bk is a suitable projectile-target combination in the current experimental conditions and the reaction 238U + 252Cf could be a promising candidate to produce unknown neutron-rich transuranium nuclides in case that the 252Cf target were to be achieved in the future.

Nuclear Reaction Mechanisms of Neutron Induced Fission of 237Np Nucleus

At FLNP JINR Dubna new prospects for developing new neutron facilities have already been started, that will replace the IBR-2 neutron pulsed research reactor which shut down in the year 2032. Several agreed projects use the fission processes induced by neutrons on neptunium-based fuels. An investigation of the neutron fission process on the 237Np nucleus was conducted in the present research. Several parameters were analyzed during neutron-induced fission of 237Np including the neutron cross-section, mass distributions, prompt neutron emission, isotope production, and neutron spectra. Evaluations of the above observables were conducted using TALYS – 9.1 Software, with incident neutron energies ranging from 0.4 to 25 MeV. The exact value of cross-section was obtained as 5 – 5.5 MeV in the present work, whereas from literature, it was found up to 10 MeV. Neutron spectra were analyzed and separated contributions from different nuclear reaction mechanisms were obtained. Our investigations have revealed some important yields and isotope production cross-sections that were in good agreement with literature data.

Unified description of fusion and multinucleon transfer processes within the dinuclear system model

To compare fusion-evaporation (FE) and multinucleon transfer (MNT) approaches and make more reliable predictions for producing superheavy nuclei, the unified description of FE and MNT processes is performed in the reaction $^{48}\mathrm{Ca}+^{238}\mathrm{U}$ within the (DNS) model. We extend the fusion concept in the DNS model based on the deformation degree of freedom. Our calculations support the experimental result [Nishio et al., Phys. Rev. C 77, 064607 (2008)] that compact configuration enhances the fusion probability. The experimental production cross sections of isotopes in FE and MNT processes can be simultaneously reproduced. By comparing the production cross sections in the MNT reaction $^{238}\mathrm{U}+^{248}\mathrm{Cm}$ with the FE reactions $^{48}\mathrm{Ca}+^{238}\mathrm{U}$ and $^{54}\mathrm{Cr}+^{248}\mathrm{Cm}$, we find that the FE process shows great advantages of cross sections for producing Cn isotopes and is the only approach that could produce superheavy elements beyond oganesson.

Possibilities of direct production of superheavy nuclei with Z=112–118 in different evaporation channels

The production cross sections of heaviest isotopes of superheavy nuclei with charge numbers 112–118 are predicted in the xn–, pxn–, and αxn–evaporation channels of the 48Ca-induced complete fusion reactions for future experiments. The estimates of synthesis capabilities are based on a uniform and consistent set of input nuclear data. Nuclear masses, deformations, shell corrections, fission barriers and decay energies are calculated within the macroscopic-microscopic approach for even-even, odd-Z and odd-N nuclei. For odd systems the blocking procedure is used. To find saddle points, the Imaginary Water Flow technique is used and non-axiallity is taken into account. As shown, our calculations, based on a new set of mass and barriers, agree very well with the experimentally known cross-sections, especially in the 3n–evaporation channel. The dependencies of these predictions on the mass/fission barriers tables, the ratio af/a, and fusion models are discussed. A way is shown to produce directly unknown superheavy isotopes in the 1n– or 2n–evaporation channels. The synthesis of new superheavy isotopes unattainable in reactions with emission of neutrons is proposed in the promising channels with emission of protons (σpxn≃10−200 fb) and alphas (σαxn≃50−500 fb).

Production of neutron deficient isotopes in the multinucleon transfer reaction Ca48(Elab=5.63MeV/nucleon)+Cm248

The yields of products of multinucleon transfer reaction $^{48}\mathrm{Ca}+^{248}\mathrm{Cm}$ at energy ${E}_{\mathrm{lab}}=5.63\phantom{\rule{0.28em}{0ex}}\mathrm{MeV}/\mathrm{nucleon}$ around the corresponding Coulomb barrier are analyzed within the dinuclear system model. The calculation results are compared with the experimental data obtained with the separator for heavy-ion reaction products SHIP at GSI. The model describes rather well the experimental production cross sections of isotopes with $Ng126$ but deviates from the experimental cross sections for the very neutron-deficient Pa and U isotopes.

Quantal diffusion approach for multinucleon transfer processes in theNi58,64+Pb208reactions: Toward the production of unknown neutron-rich nuclei

Background: In recent years, substantial efforts have been made for the study of multinucleon transfer reactions at energies around the Coulomb barrier both experimentally and theoretically, aiming at the production of unknown neutron-rich heavy nuclei. It is crucial to provide reliable theoretical predictions based on microscopic theories with sufficient predictive power.Purpose: This paper aims to clarify the applicability of the quantal diffusion approach based on the stochastic mean-field (SMF) theory for multinucleon transfer processes. Isotope production cross sections are evaluated for the reactions of $^{64}\mathrm{Ni}+^{208}\mathrm{Pb}$ at ${E}_{\mathrm{c}.\mathrm{m}.}$ $=$ 268 MeV and $^{58}\mathrm{Ni}+^{208}\mathrm{Pb}$ at ${E}_{\mathrm{c}.\mathrm{m}.}$ $=$ 270 MeV and are compared with available experimental data.Methods: Three-dimensional time-dependent Hartree-Fock (TDHF) calculations are carried out for a range of initial orbital angular momenta with Skyrme SLy4d functional. Quantal diffusion equations, derived based on the SMF theory, for variances and covariance of neutron and proton numbers of reaction products are solved, with microscopic drift and diffusion coefficients obtained from time evolution of occupied single-particle orbitals in TDHF. Secondary de-excitation processes, both particle evaporation and fission, are simulated by a statistical compound-nucleus de-excitation model, gemini++.Results: Dynamics of a fast isospin equilibration process followed by a slow drift toward the mass symmetry are commonly observed, as expected. Various reaction outcomes are evaluated, including average mass and charge numbers of reaction products, total kinetic energy loss (TKEL), scattering angle, contact time, and production cross sections for primary and secondary products. By comparing with the experimental data, we find that SMF and TDHF quantitatively reproduce experimental data for few-nucleon-transfer channels around the average values. In contrast, for many-nucleon-transfer channels, we find that the SMF approach provides much better description of the experimentally measured isotopic distributions. The results underline the importance of beyond-mean-field effects, especially one-body (mean-field) fluctuations and correlations, in describing multinucleon transfer processes. Moreover, through a combined analysis of SMF with a statistical model, gemini++, we find a significant contribution of transfer-induced fission, which is consistent with the experimental observation. In some cases, the SMF approach overestimates the isotopic width, requiring further improvements of the theoretical description. Possible ways to improve the description are discussed.Conclusions: The SMF approach is designed to describe the quantum many-body problem according to an ensemble of mean-field trajectories, taking into account part of many-body correlations in the description. As it requires feasible computational costs comparable to the ordinary TDHF approach, together with further model improvements, it will be a promising tool in the search for optimal reaction conditions to produce yet-unknown neutron-rich heavy nuclei through the multinucleon transfer reaction.

Possible production of neutron-rich No isotopes

We investigate possible production of neutron-rich isotopes of nobelium. We calculate the production cross sections of $^{261--266}\mathrm{No}$ in the multinucleon transfer reactions of the same projectiles ($^{36}\mathrm{S},\phantom{\rule{0.28em}{0ex}}^{40}\mathrm{Ar},\phantom{\rule{0.28em}{0ex}}^{48}\mathrm{Ca}$, and $^{50}\mathrm{Ti}$) and targets ($^{254}\mathrm{Es}$ and $^{248--251}\mathrm{Cf}$) that were used in the previous study for the possible production of neutron-rich isotopes of Md. We find that the production cross sections of neutron-rich No isotopes are about an order of magnitude smaller than those for neutron-rich Md isotopes. By combining the results for the production of neutron-rich No and Md isotopes, we suggest simple expressions which can trace the isotopic trends of the production cross sections of heavy neutron-rich isotopes. The logarithm of the production cross section is proportional to isospin of projectile or target and the $Q$ value.

Differential Production Cross Sections for Isotopes of Light Nuclei in the $$\boldsymbol{{}^{18}\textrm{O}+^{181}}$$Ta Reaction

The results of experiments performed at a high-resolution magnetic spectrometer (MAVR) are presented. The differential production cross sections for oxygen isotopes in the $${}^{18}\textrm{O}+^{181}$$ Ta reaction at the projectile energy of 10 MeV per nucleon were measured at the MAVR facility. The yield of reaction products is analyzed theoretically in the finite-range distorted-wave Born approximation (FR-DWBA method) by means of the FRESCO code. The theoretical differential cross sections are calculated for sequential neutron transfer. The contributions of the mechanisms of sequential neutron transfer and dineutron-cluster transfer to the production cross sections for the neutron-rich oxygen isotopes $${}^{20,22,24}$$ O are studied.

Approaching the neutron-rich heavy and superheavy nuclei by multinucleon transfer reactions with radioactive isotopes

The dynamical mechanism of multinucleon transfer (MNT) reactions has been investigated within the dinuclear system (DNS) model, in which the sequential nucleon transfer is described by solving a set of microscopically derived master equations. Production cross sections, total kinetic energy spectra, angular distribution of formed fragments in the reactions of $^{124,132}$Sn+ $^{238}$U/$^{248}$Cm near Coulomb barrier energies are thoroughly analyzed. It is found that the total kinetic energies of primary fragments are dissipated from the relative motion energy and rotational energy of the two colliding nuclei. The fragments are formed in the forward angle domain. The energy dependence of the angular spectra is different between projectile-like and target-like fragments. Isospin equilibrium is governed under the potential energy surface. The production cross sections of neutron-rich isotopes are enhanced around the shell closure.

Predictions of New Neutron-Rich Isotopes at N = 126 in the Multinucleon Transfer Reaction 136Xe + 194Ir

Aiming to produce new neutron-rich nuclei around $N=126$, the multi-nucleon transfer reaction $^{136}$Xe+$^{194}$Ir is investigated by using the GRAZING model and the three-dimensional time-dependent Hartree-Fock (TDHF) approach. De-excitation processes of the primary fragments are taken into account in both models. The results of GRAZING indicate that this system is a promising candidate for producing new neutron-rich isotones with $N=126$. In contrast, no such nuclei are observed in TDHF. Nucleon transfer process in TDHF collisions is studied and the relation to final isotopic production cross sections is discussed.

Isotope-production cross sections of residual nuclei in proton- and deuteron-induced reactions on 93Zr at 50 MeV/u

The isotope-production cross sections in p- and d-induced reactions on 93Zr at approximately 50 MeV/nucleon were measured by using the inverse-kinematics method at RIKEN RI Beam Factory. The measured data were compared with the previous experimental 93Zr + p, d at 105 and 209 MeV/nucleon data. This comparison represents that the isotopic distribution of production cross sections at 51 MeV p-induced reaction is appreciably different from those at 105 and 209 MeV. On the other hand, these three data sets show that the shape of isotopic distribution is similar in the case of the d-induced reaction. Also, the measured production cross sections were compared with the theoretical model calculations with Particle and Heavy Ion Transport code System (PHITS) version 3.10 in order to investigate the reproducibility of the models implemented in PHITS. The calculations well reproduced the experimental data even in such low incident energy, while several discrepancies were still seen as in the p- and d-induced reactions at 105 and 209 MeV/nucleon.

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.