Low energy nuclear reactions are possible in condensed matter because of image forces. They result from induced charges at the surface of metals or very polarizable media. The height and width of the Coulomb barrier i...Low energy nuclear reactions are possible in condensed matter because of image forces. They result from induced charges at the surface of metals or very polarizable media. The height and width of the Coulomb barrier in free space can thus be reduced. Nuclear fusion requires also the formation of a compound nucleus in one of its excited states, but two deuterons yield an α particle that has 2 excited states. They are respectively accessible at high or low energies. Since the reduction of the Coulomb barrier depends on the local curvature of the interface, cold fusion becomes autocatalytic, but heat production is controllable. Even microbes, plants and animals can produce transmutations. They are also due to image forces. This solves a basic problem in nuclear physics and there are possible applications: facilitated synthesis of superheavy elements and development of a new type of energy sources. They are moderate, but safe.展开更多
The neutron flow model predicts that neutrons start to flow freely between the approaching nuclei ^58Fe and ^208 pb at s=3fm, a length in which the effective surfaces of these nuclei are 3 fm apart. As a result of neu...The neutron flow model predicts that neutrons start to flow freely between the approaching nuclei ^58Fe and ^208 pb at s=3fm, a length in which the effective surfaces of these nuclei are 3 fm apart. As a result of neutron flow, the N/Z value rapidly reaches an equilibrium distribution. Meanwhile the system, originally in the fusion valley, is injected into the asymmetric fission valley. The dynamic process of the composite nucleus in the asymmetric fission valley is treated with a two-parameter Smoluchowski equation. It is shown that the probability to overcome the asymmetric fission barrier and to achieve compound nucleus configuration, hence the fusion cross section is obviously suppressed due to the effect of isospin equilibrium.展开更多
The ^(12)C+^(12)C fusion reaction was studied in the range of E_(c.m.)=8.9 to 21 MeV using the active-target Time Projection Chamber.With full information on all tracks of the reaction products,cross sections of the^(...The ^(12)C+^(12)C fusion reaction was studied in the range of E_(c.m.)=8.9 to 21 MeV using the active-target Time Projection Chamber.With full information on all tracks of the reaction products,cross sections of the^(12)C(^(12)C,^(8)Be)^(16)O_(g.s.)channel and the ^(12)C(^(12)C,3a)^(12)C channel could be measured down to the level of a few milibarns.The ^(12)C(^(12)C,^(8)Be)^(16)O_(g.s.)reaction channel was determined to be 10_(-8)^(+24) mb at E_(c.m.)=11.1 MeV,supporting the direct a transfer reaction mechanism.The ^(12)C(^(12)C,3α)^(12)C reaction channel was studied for the first time using an exclusive measurement.Our result does not confirm the anomaly behavior reported in the previous inclusive measurement by Kolata et al.[Phys.Rev.C 21,579(1980)].Our comparisons with statistical model calculations suggest that the 3 a channel is dominated by the fusion evaporation process at E_(c.m.)>19 MeV.The additional contribution of the 3 a channel increases the fusion reaction cross section by 10% at energies above 20 MeV.We also find that an additional reaction mechanism is needed to explain the measured cross section at E_(c.m.)<15 MeV at which point the statistical model prediction vanishes.展开更多
The dynamical process in the superheavy nucleus synthesis is studied on the basis of the two-dimensional Smoluchowski equation. Special attention is paid to the isotope dependence of the cross section for the superhea...The dynamical process in the superheavy nucleus synthesis is studied on the basis of the two-dimensional Smoluchowski equation. Special attention is paid to the isotope dependence of the cross section for the superheavy nucleus formation by means of making a comparison among the reaction systems of ^54Re＋204pb, ^56Re ＋206Pb, and ^58Fe＋^208Pb. It is found by this comparison that the formation cross section is very sensitive to the conditional saddle-point height and the neutron separation energy of the compound nucleus. Reaction systems with lower height of conditional saddle-point and smaller neutron separation energy are more favourable for the synthesis of the superheavy nucleus.展开更多
The deformation and associated optimum/uniquely fixed orientations play an important role in the syn-thesis of compound nuclei via cold and hot fusion reactions,respectively,at the lowest and highest barrier energies....The deformation and associated optimum/uniquely fixed orientations play an important role in the syn-thesis of compound nuclei via cold and hot fusion reactions,respectively,at the lowest and highest barrier energies.The choice of optimum orientation(0_(op))for the'cold or elongated'and hot or cormpact'fusion configurations of quadrupole(β_(2))deformed nuclei depends only on the+/-signs ofβ_(2)-deformation[J.Phys.G:Nucl.Part.Phys.31,631-644(2005)].In our recent study[Phys.Rev.C 101,051601(R)2020],we proposed a new sct of Oopt(iferent from the values reported for quadrupole deformed nuclei)after the inclusion of octupole deformation(up to B3)ef-fects.Using the respective 0op1 of B3-deformed nuclei for cold and hot optimum orientations,we analyzed the im-pact of the soft-and rigid-pear shapes of octupole deformed nuclei on the fusion barrier characterstics(barrier height Vg and barrier position RB).This analysis is applied to approximately 200 spherical-plus B3 deformed nucle-ar partners,that is,^(16)O,^(18)Cat octupole deformed nuclei.Compared with the compact configuration,the elongated fu-sion configuration has a relatively larger impact on the fusion barrier and cross sections ow ing to the inclusion of de-formations up to B3.Its agreement with available experimental data for the^(16)O+^(150)Sm reaction(β_(22)-0.205,β_(32)=0.055)also improves when the optimum orientation degree of freedom is fixed in view of octupole deformations.This reinforces the fact that nuclear structure effects play an important role in the nuclear fusion process.Thus,octu-pole deformed nuclei can be used for the synthesis of heavy and superheavy nuclei.展开更多
The reactions of ^16O＋^204pb, ^82Se＋^138Ba and ^96Zr＋^124Sn lead to the same compound nucleus ^220Th. In terms of the assumption that the surviving probability is independent of entrance channel, we have extracted ...The reactions of ^16O＋^204pb, ^82Se＋^138Ba and ^96Zr＋^124Sn lead to the same compound nucleus ^220Th. In terms of the assumption that the surviving probability is independent of entrance channel, we have extracted the fusion hindrance factor from the evaporation residue cross sections for the reactions of ^82Se＋^138 Ba and ^96Zr＋^124Sn and compared with the results calculated using a two-parameter Smoluchowski equation. The theoretical predictions are basically in agreement with the experimental data. It is found that the probability of forming a compact ^220Th is less than 10% for the reactions considered. For the systems more massive than ^220Th, fusion should be much more strongly suppressed due to the competition of quasifission with complete fusion. Understanding of this inhibition is essential to forming new superheavy nuclei.展开更多
Using the skyrme energy density formalism, a pocket formula is introduced for barrier heights and positions of 95 fusion reactions(48≤ZPZT≤1520) with respect to the charge and mass numbers of the interacting nuclei....Using the skyrme energy density formalism, a pocket formula is introduced for barrier heights and positions of 95 fusion reactions(48≤ZPZT≤1520) with respect to the charge and mass numbers of the interacting nuclei. It is shown that the parameterized values of RBand VBare able to reproduce the corresponding experimental data with good accuracy. Moreover, the absolute errors of our formulas are less than those obtained using the analytical parametrization forms of the fusion barrier based on the proximity versions. The ability of the parameterized forms of the barrier heights and its positions to reproduce the experimental data of the fusion cross section have been analyzed using the Wong model.展开更多
The interaction potential for spherical-deformed reaction partners is calculated. The shape, separation and orientation dependence of the interaction potential and fusion cross section of the system ^32S＋^154Sm are i...The interaction potential for spherical-deformed reaction partners is calculated. The shape, separation and orientation dependence of the interaction potential and fusion cross section of the system ^32S＋^154Sm are investigated within the double-folding model of the deformed nuclei. The effective nucleon-nucleon interaction is taken to be the M3Y-Reid potential. The density is considered for three terms of the expansion using the truncated multipole expansion method, which is a deformed Fermi shape With quadrupole and hexadecapole for the density distribution of ^154Sm. It is found for the interaction potential that the height and the position of barrier strongly depend on the deformations, the orientation angle of the deformed nucleus, and hence produce great effects on fusion cross section. The integrated fusion cross section is in good agreement with the experimental data.展开更多
The symmetric and asymmetric fusion reaction systems forming the same compound nuclei ^26Al, ^30Si, ^38Ar and ^170Hf are investigated with the frame of improved isospin dependent quantum molecular dynamics model. The ...The symmetric and asymmetric fusion reaction systems forming the same compound nuclei ^26Al, ^30Si, ^38Ar and ^170Hf are investigated with the frame of improved isospin dependent quantum molecular dynamics model. The entrance channel mass asymmetry dependence of compound nucleus formation is found by analyzing the shell correction energies, the Coulomb barriers and the fusion cross sections. The calculated fusion cross sections agree quantitatively with the experimental data. The results indicate that compound nucleus formation is favorable for the systems with larger mass asymmetry because of the smaller Coulomb contribution to the fusion barrier.展开更多
In order to understand questions about the study on cold fusion in these years, we have studied physical basis of cold fusion. Results show that even though the cold fusion is feasible theoretically in the view of phy...In order to understand questions about the study on cold fusion in these years, we have studied physical basis of cold fusion. Results show that even though the cold fusion is feasible theoretically in the view of physics, but its reaction ratio is too small to be detected, so that it has no prospect for practical usage at present. However, in order to tackle urgent problem of being poor in energy resources, we have no choice but to pay more attention to controlled thermal nuclear fusion in a considerably long period of time展开更多
A partial wave scattering matrix for the total effective complex potential of nucleus nucleus collisions is proposed to easily analyze the angular variations of elastic scattering and fusion cross-sections simultaneou...A partial wave scattering matrix for the total effective complex potential of nucleus nucleus collisions is proposed to easily analyze the angular variations of elastic scattering and fusion cross-sections simultaneously with a unique potential.The expectation value of the imaginary part of the potential calculated using the distorted waves from the full potential in the elastic channel accounts for σ_(r).This is equated to the sum of the cross-sections due to absorption in different regions of the potential where the imaginary part is actively present.The potential is taken as energy independent and features a weakly absorbing nature,which supports the resonance states in various partial wave trajectories.Therefore,these resonances show oscillatory behavior changes with respect to energy D(E_(c.m.))=d^(2)(E_(c.m.)σ_(fus))/dE_(c.m.)^(2).In this paper,we discuss elastic scattering and fusion cross-sections in conjunction with the results of D(E_(c.m.))for the^(16)+^(92)Zr system.展开更多
Fusion-evaporation cross sections of^(238)U(^(9)Be,5n)^(242)Cm are measured over a wide energy range around the Coulomb barrier.These measured cross sections are compared with model calculations using two codes,namely...Fusion-evaporation cross sections of^(238)U(^(9)Be,5n)^(242)Cm are measured over a wide energy range around the Coulomb barrier.These measured cross sections are compared with model calculations using two codes,namely HIVAP2 and KE WPIE2.HIVAP2 calculations overestimate the measured fusion-evaporation cross sections by a factor of approximately 3.In KEWPIE2 calculations,two approaches,namely the Wentzel-Kramers-Brillouin(WKB)approximation and the empirical barrier-distribution(EBD)method,are used for the capture probability;both of them properly describe the measured cross sections.Additionally,fusion cross sections of^(7.9)Be+^(238)Umeas-ured in two experiments are applied to constrain model calculations further through three codes,i.e,HIVAP2,KEWPIE2,and CCFULL.Parameters in these codes are also examined by comparison with measured fusion cross sections.AIll the comparisons indicate that the K EWPIE2 calculations using the WKB approximation agree well with the measured cross sections of both fusion reactions 7.9 Be+^(238)U and the fusion-evaporation reaction 238U(9 Be,5n)242 Cm.Calculations using the fusion code CCFULL are also in good agreement with the measured fusion cross sections of 7.9 Be+^(238)U.展开更多
文摘Low energy nuclear reactions are possible in condensed matter because of image forces. They result from induced charges at the surface of metals or very polarizable media. The height and width of the Coulomb barrier in free space can thus be reduced. Nuclear fusion requires also the formation of a compound nucleus in one of its excited states, but two deuterons yield an α particle that has 2 excited states. They are respectively accessible at high or low energies. Since the reduction of the Coulomb barrier depends on the local curvature of the interface, cold fusion becomes autocatalytic, but heat production is controllable. Even microbes, plants and animals can produce transmutations. They are also due to image forces. This solves a basic problem in nuclear physics and there are possible applications: facilitated synthesis of superheavy elements and development of a new type of energy sources. They are moderate, but safe.
基金Supported by the National Natural Science Foundation of China under Grants Nos 10235020 and 10235030, and the Major State Basic Research Development Programme under Grant No G200007400.
文摘The neutron flow model predicts that neutrons start to flow freely between the approaching nuclei ^58Fe and ^208 pb at s=3fm, a length in which the effective surfaces of these nuclei are 3 fm apart. As a result of neutron flow, the N/Z value rapidly reaches an equilibrium distribution. Meanwhile the system, originally in the fusion valley, is injected into the asymmetric fission valley. The dynamic process of the composite nucleus in the asymmetric fission valley is treated with a two-parameter Smoluchowski equation. It is shown that the probability to overcome the asymmetric fission barrier and to achieve compound nucleus configuration, hence the fusion cross section is obviously suppressed due to the effect of isospin equilibrium.
基金Supported in part by the Strategic Priority Research Program of Chinese Academy of Sciences(XDB34020200)the National Key Research and Development program(MOST 2016YFA0400501)from the Ministry of Science and Technology of China+2 种基金the State Key Laboratory of Nuclear Physics and Technology,PKU(NPT2020KFY06)the National Natural Science Foundation of China(U1632142,12175156),the National Natural Science Foundation of China(11905260)the Western Light Project of Chinese Academy of Sciences。
文摘The ^(12)C+^(12)C fusion reaction was studied in the range of E_(c.m.)=8.9 to 21 MeV using the active-target Time Projection Chamber.With full information on all tracks of the reaction products,cross sections of the^(12)C(^(12)C,^(8)Be)^(16)O_(g.s.)channel and the ^(12)C(^(12)C,3a)^(12)C channel could be measured down to the level of a few milibarns.The ^(12)C(^(12)C,^(8)Be)^(16)O_(g.s.)reaction channel was determined to be 10_(-8)^(+24) mb at E_(c.m.)=11.1 MeV,supporting the direct a transfer reaction mechanism.The ^(12)C(^(12)C,3α)^(12)C reaction channel was studied for the first time using an exclusive measurement.Our result does not confirm the anomaly behavior reported in the previous inclusive measurement by Kolata et al.[Phys.Rev.C 21,579(1980)].Our comparisons with statistical model calculations suggest that the 3 a channel is dominated by the fusion evaporation process at E_(c.m.)>19 MeV.The additional contribution of the 3 a channel increases the fusion reaction cross section by 10% at energies above 20 MeV.We also find that an additional reaction mechanism is needed to explain the measured cross section at E_(c.m.)<15 MeV at which point the statistical model prediction vanishes.
基金Supported by the National Natural Science Foundation of China under Grants Nos 10235020 and 10235030, and the Major State Basic Research and Development Programme of China under Grant No G200007400.
文摘The dynamical process in the superheavy nucleus synthesis is studied on the basis of the two-dimensional Smoluchowski equation. Special attention is paid to the isotope dependence of the cross section for the superheavy nucleus formation by means of making a comparison among the reaction systems of ^54Re＋204pb, ^56Re ＋206Pb, and ^58Fe＋^208Pb. It is found by this comparison that the formation cross section is very sensitive to the conditional saddle-point height and the neutron separation energy of the compound nucleus. Reaction systems with lower height of conditional saddle-point and smaller neutron separation energy are more favourable for the synthesis of the superheavy nucleus.
基金The financial support from Council of Scientific&Industrial Research(CSIR)in the form of a Senior Research Fellowship,DAE,Government of India,sanction no.58/14/12/2019-BRNSUGC-DAE consortium for Scientific Research,File No.UGC-DAE-CSR-KC/CRS/19/NP09/0920 are gratefully acknowledged。
文摘The deformation and associated optimum/uniquely fixed orientations play an important role in the syn-thesis of compound nuclei via cold and hot fusion reactions,respectively,at the lowest and highest barrier energies.The choice of optimum orientation(0_(op))for the'cold or elongated'and hot or cormpact'fusion configurations of quadrupole(β_(2))deformed nuclei depends only on the+/-signs ofβ_(2)-deformation[J.Phys.G:Nucl.Part.Phys.31,631-644(2005)].In our recent study[Phys.Rev.C 101,051601(R)2020],we proposed a new sct of Oopt(iferent from the values reported for quadrupole deformed nuclei)after the inclusion of octupole deformation(up to B3)ef-fects.Using the respective 0op1 of B3-deformed nuclei for cold and hot optimum orientations,we analyzed the im-pact of the soft-and rigid-pear shapes of octupole deformed nuclei on the fusion barrier characterstics(barrier height Vg and barrier position RB).This analysis is applied to approximately 200 spherical-plus B3 deformed nucle-ar partners,that is,^(16)O,^(18)Cat octupole deformed nuclei.Compared with the compact configuration,the elongated fu-sion configuration has a relatively larger impact on the fusion barrier and cross sections ow ing to the inclusion of de-formations up to B3.Its agreement with available experimental data for the^(16)O+^(150)Sm reaction(β_(22)-0.205,β_(32)=0.055)also improves when the optimum orientation degree of freedom is fixed in view of octupole deformations.This reinforces the fact that nuclear structure effects play an important role in the nuclear fusion process.Thus,octu-pole deformed nuclei can be used for the synthesis of heavy and superheavy nuclei.
基金Supported by the National Natural Science Foundation of China under Grants Nos 10235020 and 10235030.
文摘The reactions of ^16O＋^204pb, ^82Se＋^138Ba and ^96Zr＋^124Sn lead to the same compound nucleus ^220Th. In terms of the assumption that the surviving probability is independent of entrance channel, we have extracted the fusion hindrance factor from the evaporation residue cross sections for the reactions of ^82Se＋^138 Ba and ^96Zr＋^124Sn and compared with the results calculated using a two-parameter Smoluchowski equation. The theoretical predictions are basically in agreement with the experimental data. It is found that the probability of forming a compact ^220Th is less than 10% for the reactions considered. For the systems more massive than ^220Th, fusion should be much more strongly suppressed due to the competition of quasifission with complete fusion. Understanding of this inhibition is essential to forming new superheavy nuclei.
文摘Using the skyrme energy density formalism, a pocket formula is introduced for barrier heights and positions of 95 fusion reactions(48≤ZPZT≤1520) with respect to the charge and mass numbers of the interacting nuclei. It is shown that the parameterized values of RBand VBare able to reproduce the corresponding experimental data with good accuracy. Moreover, the absolute errors of our formulas are less than those obtained using the analytical parametrization forms of the fusion barrier based on the proximity versions. The ability of the parameterized forms of the barrier heights and its positions to reproduce the experimental data of the fusion cross section have been analyzed using the Wong model.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10275092 and 10675169.
文摘The interaction potential for spherical-deformed reaction partners is calculated. The shape, separation and orientation dependence of the interaction potential and fusion cross section of the system ^32S＋^154Sm are investigated within the double-folding model of the deformed nuclei. The effective nucleon-nucleon interaction is taken to be the M3Y-Reid potential. The density is considered for three terms of the expansion using the truncated multipole expansion method, which is a deformed Fermi shape With quadrupole and hexadecapole for the density distribution of ^154Sm. It is found for the interaction potential that the height and the position of barrier strongly depend on the deformations, the orientation angle of the deformed nucleus, and hence produce great effects on fusion cross section. The integrated fusion cross section is in good agreement with the experimental data.
基金Supported by National Natural Science Foundation of China (10847136)Fundamental Research Funds for the Central Universities (JUSRP10911)+1 种基金National Program on Key Basic Research Project (G2010CB832903)Specialized Research Fund for the Doctoral Programme of Higher Education of China (200800270017)
文摘The symmetric and asymmetric fusion reaction systems forming the same compound nuclei ^26Al, ^30Si, ^38Ar and ^170Hf are investigated with the frame of improved isospin dependent quantum molecular dynamics model. The entrance channel mass asymmetry dependence of compound nucleus formation is found by analyzing the shell correction energies, the Coulomb barriers and the fusion cross sections. The calculated fusion cross sections agree quantitatively with the experimental data. The results indicate that compound nucleus formation is favorable for the systems with larger mass asymmetry because of the smaller Coulomb contribution to the fusion barrier.
基金This work was supported by the National Natural science Foundation of China, No. 10148003.
文摘In order to understand questions about the study on cold fusion in these years, we have studied physical basis of cold fusion. Results show that even though the cold fusion is feasible theoretically in the view of physics, but its reaction ratio is too small to be detected, so that it has no prospect for practical usage at present. However, in order to tackle urgent problem of being poor in energy resources, we have no choice but to pay more attention to controlled thermal nuclear fusion in a considerably long period of time
文摘A partial wave scattering matrix for the total effective complex potential of nucleus nucleus collisions is proposed to easily analyze the angular variations of elastic scattering and fusion cross-sections simultaneously with a unique potential.The expectation value of the imaginary part of the potential calculated using the distorted waves from the full potential in the elastic channel accounts for σ_(r).This is equated to the sum of the cross-sections due to absorption in different regions of the potential where the imaginary part is actively present.The potential is taken as energy independent and features a weakly absorbing nature,which supports the resonance states in various partial wave trajectories.Therefore,these resonances show oscillatory behavior changes with respect to energy D(E_(c.m.))=d^(2)(E_(c.m.)σ_(fus))/dE_(c.m.)^(2).In this paper,we discuss elastic scattering and fusion cross-sections in conjunction with the results of D(E_(c.m.))for the^(16)+^(92)Zr system.
基金the National Natural Science Foundation of China(12005314,11805289,11875328,11775316)the ELI-NP Phase II,a project co-financed by the Romanian Government and the European Union through the European Regional Development Fund-the Competitiv eness Operational Programme(1/07.07.2016,COP,ID 1334)。
文摘Fusion-evaporation cross sections of^(238)U(^(9)Be,5n)^(242)Cm are measured over a wide energy range around the Coulomb barrier.These measured cross sections are compared with model calculations using two codes,namely HIVAP2 and KE WPIE2.HIVAP2 calculations overestimate the measured fusion-evaporation cross sections by a factor of approximately 3.In KEWPIE2 calculations,two approaches,namely the Wentzel-Kramers-Brillouin(WKB)approximation and the empirical barrier-distribution(EBD)method,are used for the capture probability;both of them properly describe the measured cross sections.Additionally,fusion cross sections of^(7.9)Be+^(238)Umeas-ured in two experiments are applied to constrain model calculations further through three codes,i.e,HIVAP2,KEWPIE2,and CCFULL.Parameters in these codes are also examined by comparison with measured fusion cross sections.AIll the comparisons indicate that the K EWPIE2 calculations using the WKB approximation agree well with the measured cross sections of both fusion reactions 7.9 Be+^(238)U and the fusion-evaporation reaction 238U(9 Be,5n)242 Cm.Calculations using the fusion code CCFULL are also in good agreement with the measured fusion cross sections of 7.9 Be+^(238)U.
