Incomplete Fusion Reactions Research Articles

A Systematic Study: Some Insights into the Low-energy Incomplete Fusion Reactions

A Systematic Study: Some Insights into the Low-energy Incomplete Fusion Reactions

Towards Understanding Incomplete Fusion Reactions at Low Beam Energies: Modified Sum Rule Model

We investigated the enhanced production of nuclei formed via incomplete fusion (ICF) reactions near and above the Coulomb barrier energies (5–8 MeV/A). The cross-sections of the evaporation residues formed in the reactions—11B+124Sn, 10B+124Sn and 11B+122Sn—were measured using off-line gamma-ray spectrometry. The sum rule model (SRM) by Wilczyński et al. predicted the cross-section values too low compared to our experimental results. In earlier studies, the same model has been very successful in explaining ICF reactions at high beam energies (>10 MeV/A). We, therefore, modified the SRM, specifically incorporating the energy dependence in the definition of critical angular momentum ℓcr. The resulting modified SRM gave an improved theoretical estimate for the reactions we studied.

A Study of Complete and Incomplete Reactions of 12C + 169Tm System at Energy Range ≈ 4.16 –7.5 MeV/Nucleon

An attempt was made in this study to measure the excitation functions of 169Tm(12C, 4n)177Re, 169Tm(12C, 5n)176Re, 169Tm(12C, αn)176Ta, 169Tm(12C, α2n)175Ta, 169Tm(12C, α3n) 174Ta, 169Tm(12C, α4n)173Ta and 169Tm(12C, 2α2n)171Lu reaction channels populated in the interaction of 12C projectile with 169Tm target were considered in order to investigate the mechanisms of complete and incomplete fusion reactions. The theoretically predicted excitation functions using the PACE4 code were compared with the previously measured excitation functions. For non α emitting channels cross-section values predicted by PACE4 in general were found to be in good agreement with the experimentally measured values. However, for α-emitting channels, the measured cross-section values were found to be higher than the values predicted by PACE4. The observed disagreement may be credited to projectile break-up in the vicinity of n-n interaction.

Incomplete fusion reaction producing Pa nuclides in the 232Th + 7Li reaction

Abstract The 237Np (t 1/2 = 2.1 × 106 y) nuclide is produced in nuclear facilities. Its investigation is relevant to earth sciences as concerns environmental pollution and material circulation. We expected that this nuclide should be able to be analyzed by mass spectrometry with a neptunium tracer as a spike, such as that of 236gNp (t 1/2 = 1.5 × 105 y). Our research group has collected fundamental data for cross-sections of the 232Th + 7Li reaction for use in spike production. In addition to the complete fusion reaction, incomplete fusion also occurs, especially in the reaction of 7Li, which splits into α and t, and only a part of the projectile fuses with the target nucleus. In this study, the excitation functions of Pa isotopes, as products of the incomplete fusion reaction, were measured. The reaction mechanism is discussed by comparing the experimental values with those calculated using the EMPIRE code. In addition, we investigated the effect of incomplete fusion reaction on the entire reaction.

Understanding the low-energy incomplete fusion reactions

With a motivation to find out the systematics for the low-energy ($\ensuremath{\approx}4$--7 MeV/nucleon) incomplete fusion reactions, the experimentally measured excitation functions for evaporation residues, which were populated during the interactions of $^{18}\mathrm{O}$ with $^{159}\mathrm{Tb}$ target nuclei, have been studied. The analysis clearly exhibits that the $xn/pxn$ channels are populated to a large extent through the complete fusion processes. Although, the production cross-section of the $\ensuremath{\alpha}$-emitting channels, despite of deducting the precursor decay contribution, found to be significantly under-estimated by the statistical model predictions. The observed enhancement, which may be attributed due to the involvement of break-up fusion processes, is found to be get larger with the incident energy. In addition, the present work in light of the literature data imparts the reliance of incomplete fusion processes on various entrance channel parameters, such as the mass-asymmetry of the interacting partners, fissility parameter and also on the ${Z}_{P}{Z}_{T}$ (Coulomb factor). These systematics inarguably indicates the projectile type dependency of the incomplete fusion reactions, and the results may be explained on the basis of the $\ensuremath{\alpha}\text{\ensuremath{-}}Q$ value of the projectile. Furthermore, an attempt has been made to explain the trends of incomplete fusion fractions through the total asymmetry parameter and the system parameter, where system parameter seems to explain the data more satisfactorily, as it incorporates the Coulomb factor as well as the masses of the interacting partners.

Low Energy Incomplete Fusion Reactions: Probing of Entrance Channel Effect

Low Energy Incomplete Fusion Reactions: Probing of Entrance Channel Effect

A Study of Reaction Dynamics in the Interaction of 14N+59Co System at 32-56 MeV

The present work was done to investigate the reaction mechanisms involved in the interaction of 14 N projectile with 59 Co target at beam energies ∼32-56 MeV. The experimentally measured excitation functions available in the literature [2] were compared and analyzed with the statistical model code PACE4 calculation. For non-α emitting channels populated via complete fusion reaction, the measured excitation functions, after correcting them for possible contributions coming from higher charge isobaric precursor decays, were in general found to be in good agreement with theoretical predictions. However, for α-emitting channels, the experimentally measured excitation functions had more production cross-sections than what PACE4 predicted. The observed enhancement in the present case may be attributable to process of incomplete fusion from break-up of 14 N projectile. It may be pointed out that incomplete fusion reaction increases with increase in projectile energy. The observation of high incomplete fusion reaction is attributable to the prompt breakup of 14 N projectile into α-cluster. DOI: 10.7176/APTA/86-03 Publication date: October 31 st 2022

Study of incomplete fusion reaction dynamics for the system 14N + 169Tm using the forward Recoil Range distribution technique

Studies in the past have demonstrated that complete fusion and incomplete fusion (ICF) dynamics are both significant just above the Coulomb barrier, yet the dynamics of ICF are elusive since they are so complex below 10 MeV/nucleon. In order to investigate low-energy ICF dynamics, we measured the forward recoil range distribution (FRRD) of evaporation residues (ERs) populated in the system 14N + 169Tm at energy ≈5.9 MeV/nucleon. A stack target-catcher activation technique followed by offline-γ-spectroscopy was used to estimate the FRRD of the ERs. In order to investigate a new parameter for describing ICF dynamics, the ICF fraction (F ICF(%)) for the present system was estimated from the range-integrated cross-sections and compared with other systems in the literature. The FRRD and range integrated cross-sections of seven ERs have been estimated experimentally. These cross-section results agree well with the experimental results obtained from the excitation functions. On re-investigation of entrance channel systematics for Q α -value of projectile, mass-asymmetry (μ MA), and Coulomb factor (Z P Z T), it has been found that the Q α -value systematic for 14N is not valid at all projectile energies. The FRRD measurement is one of the direct methods available to probe the complete and ICF contributions in ERs at low projectile energy. It has also been observed that the dynamics of ICF are not only dependent on the parameters of one entrance channel but on multiple entrance channels. We have also introduced the entrance channel parameter zeta (ζ) for the first time in ICF reactions to see the combined effect of mass-asymmetry (μ MA) and Z P Z T, as this parameter is better suited than μ MA and Z P Z T individually and has a linear dependency on F ICF(%).

Rare isotope formation in complete fusion and multinucleon transfer reactions in collisions of Ca48+Cm248 near Coulomb barrier energies

Within the framework of the dinuclear system model, the reaction mechanisms for synthesizing target-like isotopes from Bk to compound nuclei Lv are thoroughly investigated in complete and incomplete fusion reaction of $^{48}$Ca +$^{248}$Cm around Coulomb barrier energies. Production cross-section of $^{292,293}$Lv as a function of excitation energy in fusion-evaporation reactions and target-like isotopic yields in multinucleon transfer reactions are evaluated, in which a statistical approach is used to describe the decay process of excited nuclei. The available experimental data can be reproduced well with the model reasonably. The products of all possible formed isotopes in the dynamical pre-equilibrium process for collision partners at incident energy $E_{\rm lab}$ = 5.5 MeV/nucleon are exported, systematically. It is found that the quasi-fission fragments are dominant in the yields. The optimal pathway from the target to compound nuclei shows up along the valley of potential surface energy. The effective impact parameter of two colliding partners leading to compound nuclei is selected from head-on collision to semi-central collision with $L$ = 52 $\rm \hbar$. The timescale boundary between complete fusion and multinucleon transfer reactions is about 5.7$\times 10^{-21}$ s with effective impact parameters. Synthesis cross-section of unknown neutron-rich actinides from Bk to Rf have been predicted around several nanobarns.

Effect of non- α -cluster projectile on incomplete-fusion dynamics: Experimental study of the N14+Ta181 system

In order to study incomplete fusion (ICF) reaction dynamics, the present work manifests the role of a non-$\ensuremath{\alpha}$-cluster $^{14}\mathrm{N}$ projectile on $^{181}\mathrm{Ta}$ target at energies $\ensuremath{\approx}4--7$ MeV/nucleon using the offline $\ensuremath{\gamma}$-ray spectroscopy. The excitation functions for 15 reaction residues populated in $^{14}\mathrm{N}+^{181}\mathrm{Ta}$ system have been measured and analyzed within the framework of statistical model code PACE4. The experimentally measured excitation functions of evaporation residues populated via xn/pxn channels are found to be well reproduced by the predictions of code PACE4, which confirms their production solely via complete fusion process. However, an enhancement in the measured excitation function as compared to PACE4 calculations, particularly in tail portion of $^{192}\mathrm{Hg}$ residue ($3n$ channel) has been observed indicating the presence of precompound emission. A significant contribution from precursor decay in pxn channels has also been observed. An enhancement in the measured excitation functions for $\ensuremath{\alpha}$-emitting channels as compared to the PACE4 predictions has been observed and attributed to the incomplete fusion process. Further, the contribution from incomplete fusion process in the $^{14}\mathrm{N}+^{181}\mathrm{Ta}$ system has also been deduced in terms of strength function (${F}_{\mathrm{ICF}}$). The results have been discussed in terms of the parameters which influence the dynamics of ICF process. The ${F}_{\mathrm{ICF}}$ is found to depend strongly on projectile energies, the product of projectile and target charges, and $\ensuremath{\alpha}\ensuremath{-}Q$ value of the projectile.

Projectile Break-up Effect on Fusion in 16O + 156Gd Reaction at Energy Range 4.3-6.3 MeV/A

We discuss our present understanding of the incomplete fusion (ICF) reaction dynamics, the excitation function of six evaporation residues (ERs) have been measured in 16O + 156Gd reaction at projectile energy range, E/A ~ 4.3-6.3 MeV/Nucleon. Some of the ERs are produced directly & indirectly (i.e. through pre-cursor), the pre-cursor contributions have been separated out from the measured cumulative cross-section with the help of Cavinato et al.1. After correcting the pre-cursor contribution, the independent yield has been compared with the statistical model code PACE-22, which describes the fusion reaction cross section. In order to optimize the parameter of the code PACE-2 that reproduces the cross section of all the complete fusion (CF) channels like xn and /or pxn-channels. Using the same set of input parameters, cross section of the ERs populated via incomplete fusion (ICF) channels have been measured. The enhancement in the measured cross section of the ERs populated via ICF channels over the PACE-2 prediction have been measured, which indicates the occurrence of the break-up of projectile 16O into (12C+α) and/or (8Be+2α) leading to ICF reaction dynamics.

Production of transuranium isotopes in Ne20 -induced incomplete fusion reactions

Using a semiclassical dynamical model that combines a classical trajectory model with stochastic breakup with a dynamical fragmentation theory treatment of two-body clusterization and decay of a projectile, results are presented for $^{20}\mathrm{Ne}$-induced incomplete fusion reactions for the production of superheavy elements. Targets include $^{247,248,250}\mathrm{Cm}$ and $^{251,252,254}\mathrm{Cf}$, and results include angular, excitation energy, and angular momentum distributions in addition to total integrated cross sections for heavy incomplete fusion products. The results show that at Coulomb energies, the studied Cf isotopes are generally the more favorable choice of target over the studied Cm isotopes for the production of `colder' and more stable $^{263}\mathrm{Lr}$, $^{263,264,266}\mathrm{Rf}$, and $^{265}\mathrm{Db}$ isotopes through the incomplete fusion mechanism. Also presented are evaporation residue cross sections for the dominant primary incomplete fusion products of each of the six reactions: $^{263,264,266}\mathrm{Rf}$ and $^{267,268,270}\mathrm{Sg}$, as well as for the primary incomplete fusion products $^{269,270,272}\mathrm{Bh}$.

Variation of ICF strength function with projectile energy for 12C + 165Ho system at Elab ≤ 7MeV/A

During the last few decades, research in heavy-ion induced nuclear reactions has opened numerous fields, in its theoretical and experimental domains. At energies, from near the Coulomb barrier to well above it, the complete fusion (CF) and incomplete fusion (ICF) reactions compete with each other. The relative contribution of these processes depends on various entrance channel parameters. In order to study the dependence of CF and ICF reaction dynamics on various entrance channel parameters, comparative studies with different parameters of the statistical model codes have been done. In this paper, an attempt has been made to study the dependence of incomplete fusion strength function on incident energy for 12 C + 165 Ho system at energies ≤ 7 MeV/A. The analysis of data has been done within the frame work of statistical model code PACE4, which do not take ICF into account; and thus predicts cross-section values only due to complete fusion process. For the present reaction system, the excitation functions (EFs) of xn/pxn channels, predicted by PACE4 code, well reproduces the experimentally measured values, indicating their production via CF process only. However, for α and 2α-emitting channels, calculated EFs through PACE4 code underpredict the experimentally measured cross-sections by »25-30%, in general. The enhancement of experimental cross-sections for α and 2α-emitting channels as compared to the PACE4 predictions, indicates that the major contribution of their production comes from the ICF of 12 C, if it breaks up into 8 Be and α-fragments, and one of the fragments fuses with the target nucleus. The incomplete fusion strength function (F ICF ), which gives relative importance of ICF processes over CF process has also been deduced and is found to depend sensitively on beam energy.

Systematic study of incomplete fusion reactions: Role of various entrance channel parameters

The evaporation residues, populated through complete and incomplete fusion processes in the reaction of 18O+ 165Ho, have been analyzed via excitation function measurements at projectile energies ≈ 4-7 MeV/nucleon. The cross-sections measured experimentally have been compared with the predictions of the compound nucleus model code PACE-4 calculations which only considers complete fusion (CF) reaction cross-sections. The experimental cross-section of the reaction residues populated through xn and pxn channels matches well with the theoretical model code PACE-4 predictions. On the other hand, α-emitting channels show an enhancement in the measured cross-section over PACE-4 calculations which reveals the occurrence of incomplete fusion (ICF) at the studied energy range. The relative percentage of incomplete fusion has been calculated from the experimental data and its dependence on various entrance channel parameters like projectile energy, mass-asymmetry, α-Q value and Coulomb factor (ZPZT) has been studied. The strength of incomplete fusion function obtained in the 18O+ 165Ho interaction has been compared with the previously studied systems. Results of the present study indicate that 18O (two neutron excess) projectile shows more incomplete fusion contribution as compared to 12C,13C and 16O projectiles due to its relatively small negative α-Q value.

Study of Complete and Incomplete Fusion Reaction in the Interaction of 12C+ 128 Te and 14N + 128 Te system below 7 MeV/A.

In this paper, an attempt was made to measure the excitation function for the disappearance residues recognized in the interaction of 12 C+ 128 Te and 14 N + 128 Te system with the observation to investigating the complete and incomplete fusion reaction dynamics in heavy ion induced reaction. The incentive of this study was break up of 12 C and 14 N in reaction below 7MeV/A and associate the excitation function for 12 C and 14 N with the same target 128 Te prominent different compound system. PACE-4 were used for analysis of the system, and the measured excitation functions for precise decay channel in two case i.e. ( 12 C+ 128 Te and 14 N + 128 Te) have been associated and established in Bohr assumption in case of complete fusion channels. The properties of coulomb barrier and other entrance channel parameters were established to be relatively significant in decisive the decay mode of composite system. Additionally the incomplete fusion dynamics were also perceived to be of significant importance in present energy section. Keywords : Complete Fusion, Incomplete fusion, non-α-emitting, α-emitting DOI : 10.7176/APTA/81-01 Publication date: December 31 st 2019

Populating high spin states of a compound nucleus with the incomplete fusion mechanism: the effectiveness of heavy projectiles

Using a classical dynamical reaction model, angular momentum (L) values of a compound nucleus due to incomplete fusion (ICF) at energies near and above the Coulomb barrier are studied. In this model, a projectile consisting of two cluster nuclei is fired at a stationary target nucleus. After breakup of the projectile due to Coulombic and nuclear forces, an α-cluster fuses with a 208Pb target, forming an excited 212Po compound nucleus. Results show that all ICF reactions produced higher angular momentum in the compound nucleus compared to a direct beam of α particles at the same incident energy. The highest angular momentum values produced in 212Po for near and above Coulomb barrier energies were obtained using a 20Ne projectile at and , respectively. This produced 25% and 50% L values above the next highest-Z projectile used, 8Be, respectively.

Investigating entrance channel influences in the fusion of some heavy–ion systems

The dynamics of heavy-ion fusion reaction involved in the interaction of 12C,14N and 16O projectiles with,59Co, 51V,128Te and165Ho targets at≈3-8MeV/nucleon specific energies was studied. This study focus on the correlation between entrance channel properties and incomplete fusion reaction. The experimentally measured excitation functions of various reaction products populated by complete and/or incomplete fusions of 12C+59Co, 128Te,14N+128Teand 16O+ 51V, 165Hoprojectile-target systems available in the literature. Were compared and analyzed with the predicted excitation functions, using the statistical model code PACE4. For representative non-α-emitting channels, the experimentally measured excitation functions were, in general, found to be in good agreement with the theoretical predictions. However, for α-emitting channels in the present systems, the measured excitation functions were higher than the predictions of the theoretical model code, which may be credited to incomplete fusion reactions at these energies. An attempt was made to approximate the incomplete fusion fraction that explains the relative importance of incomplete fusion processes. The incomplete fusion fraction was found to be sensitive to the projectile energy and mass-asymmetry of the entrance channel

Investigating the Influence of Incomplete Fusion on Complete Fusion of 16 O –Induced Reaction ≈ 3-8 MeV/nucleon

The dynamics of heavy-ion fusion reaction elaborate in the interaction of 1616O "> projectiles with 16165Ho "> and 51 V targets at ≈3-8MeV/nucleon specific energies were studied. This study were emphases on the relationship between entrance channel belongings and incomplete fusion reaction. The experimentally measured excitation functions of various reaction products duplicated by complete or incomplete fusions of 1616O "> + 1651V"> , 16165Ho "> projectile-target systems had been compared and analyzed within the predicted excitation functions, using the statistical model code PACE4. For α-emitting channels in the present systems, the measured excitation functions had been highest than the predictions of the theoretical model code, which may focuses at these energies. However for non-alpha emitting channels in this system the measured excitation function had been nice agreement with the theoretical values. An endeavor were made to nearly the incomplete fusion fraction that designates importance of incomplete fusion process. Keywords: Alpha emitted, CF reaction, Entrance channel, Heavy ion fusion, ICF reaction, Non alpha emitted DOI : 10.7176/APTA/79-03 Publication date :September 30 th 2019

Systematic study of the break-up fusion process in the C12+Ho165 system and interplay of entrance channel parameters

To understand the low-energy incomplete fusion (ICF) reaction dynamics, the excitation function measurements of $^{12}\mathrm{C}+^{165}\mathrm{Ho}$ system has been performed in the energy region of \ensuremath{\approx} 4--7 MeV/nucleon, by employing the stacked foil activation technique. The cross sections of the measured evaporation residues are compared with the theoretical predictions of statistical model code PACE4, which takes into account only the complete fusion (CF) reaction cross section. It is observed that residues populated via xn and pxn channels are in good agreement with the PACE4 predictions, implying that these residues are populated via CF process. However, in the case of \ensuremath{\alpha}-emission channels a significant enhancement from the PACE4 predictions is observed even after the deduction of precursor contribution, which is accredited to ICF process. The projectile break-up probability is found to increase with increment in the incident projectile energy. Further, the dependence of incomplete fusion dynamics on entrance channel parameters like mass asymmetry, Coulomb effect (${Z}_{\mathrm{P}}{Z}_{\mathrm{T}}$), and projectile ${Q}_{\ensuremath{\alpha}}$ value is systematically studied. The present results reveal that a single entrance channel parameter does not oversee the ICF reaction dynamics but have varying contributions depending upon the projectile-target combination. Moreover, the effect of projectile break-up on complete fusion cross section at energies above the Coulomb barrier is also studied. The suppression in fusion cross section is observed when compared with the universal fusion function.

Enhancement of element production by incomplete fusion reaction with weakly bound deuteron

Searching for effective pathways for the production of proton-rich and neutron-rich isotopes is one of the main driving forces behind experimental and theoretical nuclear reaction studies as well as for practical applications in nuclear transmutation of radioactive waste. To produce nuclei effectively, an optimal combination of reaction mechanism and energy is required. We report a study on incomplete fusion induced by deuteron, which contains one proton and one neutron with a weak binding energy and is easily broken up. This reaction study was achieved by measuring directly the cross sections for both proton and deuteron for 107Pd at 50 MeV/u via inverse kinematics technique. The results provide direct experimental evidence for the onset of a cross-section enhancement at high energy, indicating the potential for incomplete fusion induced by loosely-bound nuclei for creating proton-rich isotopes and nuclear transmutation of radioactive waste.