Isonucleosides were synthesized by the reaction of suger epoxide and nucleobase in the presence o... more Isonucleosides were synthesized by the reaction of suger epoxide and nucleobase in the presence of K2C03 and crown ether. The substitution is regioselective. Some of isonucleoside derivatives showed significant activities of cytotoxcity in HL-60 cells. Oligodeoxynucleotides incorporated with isonucleoside have a increase in stability towardes nuclease S 1. A number of analogues of nucleosides have been found to possess anti-cancer and antiviral activities.14 Isonucleoside is a new class of nucleoside analogues in which the nucleobase is linked to the position of ribose other than Clt. Therefore isonucleoside attracted much attention owing to their chemical and enzymatic stability and potential antiviral activities5. A series of isomeric of 2',3'-dideoxynucleosides which contain a modified carbohydrate moiety have been synthesized and some of the compounds exhibited significant and selective anti-HIV activity"'. New regioisomer of AZT, AZU, BVDU and IDU have also been investigated'. Many isonucleosides syntheses have made use of epoxide opening by the a i d e anion, subsequent reduction furnishes the amine which is used to build up the heterocyclic moiety. An alternative synthesis involved the nucleophilic substitution of leaving group in the sugar ring by heterocyclic moiety under basic condition. In order to avoid the lengthy synthetic routes, we synthesized the isonucleosides using epoxide opening by the nucleobase itself in the basic c~ndition.~ The desired epoxide can be obtained from corresponding sugar.
We report on a comprehensive systematics of fusion-evaporation and/or fusionfission cross section... more We report on a comprehensive systematics of fusion-evaporation and/or fusionfission cross sections for a very large variety of systems over an energy range 4A-155A MeV. Scaled by the reaction cross sections, fusion cross sections do not show a universal behavior valid for all systems although a high degree of correlation is present when data are ordered by the system mass asymmetry. For the rather light and close to mass-symmetric systems the main characteristics of the complete and incomplete fusion excitation functions can be precisely determined. Despite an evident lack of data above 15A MeV for all heavy systems the available data suggests that geometrical effects could explain the persistence of incomplete fusion at incident energies as high as 155A MeV.
Different Liquid Drop Model mass formulae have been studied. They include a Coulomb diffuseness c... more Different Liquid Drop Model mass formulae have been studied. They include a Coulomb diffuseness correction Z 2 /A term and pairing and shell energies of the Thomas-Fermi model. The influence of the selected charge radius, the curvature energy and different forms of the Wigner term has been investigated. Their coefficients have been determined by a least square fitting procedure to 2027 experimental atomic masses. The different fits lead to a surface energy coefficient of 17-18 MeV. A large equivalent rms radius (r0 = 1.22 − 1.24 fm) or a shorter central radius may be used. A rms deviation of 0.54 MeV can be reached between the experimental and theoretical masses. The remaining differences come from the determination of the shell and pairing energies. Mass predictions are given for exotic nuclei.
EPJ manuscript No. (will be inserted by the editor) On the liquid drop model mass formulae and ch... more EPJ manuscript No. (will be inserted by the editor) On the liquid drop model mass formulae and charge radii
The efficiency of different mass formulas derived from the liquid drop model including or not the... more The efficiency of different mass formulas derived from the liquid drop model including or not the curvature energy, the Wigner term and different powers of the relative neutron excess I has been determined by a least square fitting procedure to the experimental atomic masses assuming a constant R0;charge/A 1= 3 ratio. The Wigner term and the curvature energy can be used independently to improve the accuracy of the mass formula. The different fits lead to a surface energy coefficient of around 17-18 MeV, a r sharp charge radius r0 of 1.22-1.23 fm and a proton form-factor correction to the Coulomb energy of around 0.9 MeV.
The potential energy of a deformed nucleus has been determined within a Generalized Liquid Drop M... more The potential energy of a deformed nucleus has been determined within a Generalized Liquid Drop Model taking into account the proximity energy, the microscopic corrections and compact and necked shapes. Multiple-humped potential barriers appear. A third minimum and third maximum exist in specific exit channels where one fragment is close to a magic spherical nucleus while the other one varies from oblate to prolate shapes. The heights of the fission barriers and half-lives of actinides are in agreement with the experimental results.
A great deal of research work has been undertaken in the α-clustering study since the pioneering ... more A great deal of research work has been undertaken in the α-clustering study since the pioneering discovery, half a century ago, of 12 C + 12 C molecular resonances. Our knowledge in the physics of nuclear molecules has increased considerably and nuclear clustering remains one of the most fruitful domains of nuclear physics, facing some of the greatest challenges and opportunities in the years ahead. In this work, the occurence of "exotic" shapes in light N = Z α-like nuclei is investigated. Various approaches of superdeformed and hyperdeformed bands associated with quasimolecular resonant structures are presented. Results on clustering aspects are also discussed for light neutron-rich oxygen isotopes.
Charged-particle and γ decays in 24 Mg * are investigated for excitation energies where quasimole... more Charged-particle and γ decays in 24 Mg * are investigated for excitation energies where quasimolecular resonances appear in 12 C + 12 C collisions. Various theoretical predictions for the occurrence of superdeformed and hyperdeformed bands associated with resonance structures with low spin are discussed within the measured 24 Mg * excitation energy region. The inverse kinematics reaction 24 Mg + 12 C is studied at E lab (24 Mg) = 130 MeV, an energy that enables the population of 24 Mg states decaying into 12 C + 12 C resonant breakup states. Exclusive data were collected with the Binary Reaction Spectrometer in coincidence with Euroball IV installed at the Vivitron tandem facility at Strasbourg. Specific structures with large deformation were selectively populated in binary reactions, and their associated γ decays studied. Coincident events associated with inelastic and α-transfer channels have been selected by choosing the excitation energy or the entry point via the two-body Q values. The analysis of the binary reaction channels is presented with a particular emphasis on 24 Mg-γ, 20 Ne-γ , and 16 O-γ coincidences. New information (spin and branching ratios) is deduced on high-energy states in 24 Mg and 16 O, respectively.
The interrelation of the quadrupole deformation and clusterization is investigated in the example... more The interrelation of the quadrupole deformation and clusterization is investigated in the example of the 56 Ni nucleus. The shape isomers, including superdeformed and hyperdeformed states, are obtained as stability regions of the quasidynamical U(3) symmetry based on a Nilsson calculation. Their possible binary clusterizations are investigated by considering both the consequences of the Pauli exclusion principle and the energetic preference.
The asymmetric fission barriers and the released kinetic energies in the deformation valley leadi... more The asymmetric fission barriers and the released kinetic energies in the deformation valley leading rapidly to two tangent spherical fragments have been calculated for Hg, Tb, In, Mo, and Br within the generalized liquid-drop model including the nuclear proximity energy. Results are compared to experimental data and predictions of the Yukawa plus exponential finite range liquid-drop model and the liquid-drop model. The calculated asymmetric fission barrier heights lie between the values obtained by the two other theoretical approaches.
The potential barriers governing the reactions 58 Fe + 244 Pu, 238 U + 64 Ni, and 238 U + 72 Ge h... more The potential barriers governing the reactions 58 Fe + 244 Pu, 238 U + 64 Ni, and 238 U + 72 Ge have been determined from a liquid-drop model taking into account the proximity energy, shell energies, rotational energy, and deformation of the incoming nuclei in the quasimolecular shape valley. Double-humped potential barriers appear in these entrance channels. The external saddle-point corresponds to two touching ellipsoidal nuclei when the shell and pairing effects are taken into account, while the inner barrier is due to the shell effects at the vicinity of the spherical shape of the composite system. Between them, a large potential pocket exists and persists at very high angular momenta allowing the capture of very heavy ions at high excitation energies.
The coefficients of different possible macro-microscopic mass formulae previously proposed have b... more The coefficients of different possible macro-microscopic mass formulae previously proposed have been adjusted on 2264 experimental atomic masses extracted from the AME2012 atomic mass evaluation [1] assuming N, Z ≥ 8 and the one standard deviation uncertainty on the mass lower than 150 keV. All the formulae include the volume and surface energies, the Coulomb energy, the diffuseness correction to the sharp radius Coulomb energy, the shell and pairing energies and take into account or not the curvature energy, different forms of the Wigner term, a free charge radius, the experimental equivalent rms charge radius or a fixed short central radius. Masses of 976 more exotic nuclei are extrapolated from the most accurate formula.
We systematically calculate the spontaneous fission half-lives for heavy and superheavy nuclei be... more We systematically calculate the spontaneous fission half-lives for heavy and superheavy nuclei between U and Fl isotopes. The spontaneous fission process is studied within the semi-empirical WKB approximation. The potential barrier is obtained using a generalized liquid drop model, taking into account the nuclear proximity, the mass asymmetry, the phenomenological pairing correction, and the microscopic shell correction. Macroscopic inertial-mass function has been employed for the calculation of the fission half-life. The results reproduce rather well the experimental data. Relatively long half-lives are predicted for many unknown nuclei, sufficient to detect them if synthesized in a laboratory.
The entrance and exit channels through quasimolecular shapes are compatible with the experimental... more The entrance and exit channels through quasimolecular shapes are compatible with the experimental data on fusion, light nucleus and α emissions when the proximity energy is taken into account. Analytic expressions allowing to determine rapidly this proximity energy are presented as well as formulas for the fusion barrier heights and radii and for the α emission barriers. Predictions for half-lives of exotic α emissions are proposed.
The potential barrier governing the light-nucleus emission has been determined within a generaliz... more The potential barrier governing the light-nucleus emission has been determined within a generalized liquid-drop model including the proximity effects between the light and daughter nuclei and adjusted to reproduce the experimental Q value. The partial decay half-lives have been calculated within the WKB barrier penetration probability, without introducing preformation factor. The agreement with the experimental data for the 14 C, 20 O, 23 F, 24−26 Ne, 28−30 Mg and 32 Si emission is good. Predictions for other possible decays are presented meeting two criteria: partial half-life 10 30 s and branching ratio relative to α emission 10 −24. An analytic formula is proposed for the half-life of the light-nucleus decay.
Longitudinal ternary and binary fission barriers of 36 Ar, 56 Ni and 252 Cf nuclei have been dete... more Longitudinal ternary and binary fission barriers of 36 Ar, 56 Ni and 252 Cf nuclei have been determined within a rotational liquid drop model taking into account the nuclear proximity energy. For the light nuclei the heights of the ternary fission barriers become competitive with the binary ones at high angular momenta since the maximum lies at an outer position and has a much higher moment of inertia.
Different Liquid Drop Model mass formulae have been studied. They include a Coulomb diffuseness c... more Different Liquid Drop Model mass formulae have been studied. They include a Coulomb diffuseness correction Z 2 /A term and pairing and shell energies of the Thomas-Fermi model. The influence of the selected charge radius, the curvature energy and different forms of the Wigner term has been investigated. Their coefficients have been determined by a least square fitting procedure to 2027 experimental atomic masses. The different fits lead to a surface energy coefficient of 17-18 MeV. A large equivalent rms radius (r0 = 1.22 − 1.24 fm) or a shorter central radius may be used. A rms deviation of 0.54 MeV can be reached between the experimental and theoretical masses. The remaining differences come from the determination of the shell and pairing energies. Mass predictions are given for exotic nuclei.
We report on a systematics of fusion cross section data at energies above the reaction threshold ... more We report on a systematics of fusion cross section data at energies above the reaction threshold to those of disappearance of fusion process. By an appropriate scaling of both cross sections and energy, a fusion excitation function common to all the data points is established. A universal description of the fusion excitation function relying on basic nuclear concepts is proposed and its dependence on the reaction cross section used for the cross section normalization is discussed.
Isonucleosides were synthesized by the reaction of suger epoxide and nucleobase in the presence o... more Isonucleosides were synthesized by the reaction of suger epoxide and nucleobase in the presence of K2C03 and crown ether. The substitution is regioselective. Some of isonucleoside derivatives showed significant activities of cytotoxcity in HL-60 cells. Oligodeoxynucleotides incorporated with isonucleoside have a increase in stability towardes nuclease S 1. A number of analogues of nucleosides have been found to possess anti-cancer and antiviral activities.14 Isonucleoside is a new class of nucleoside analogues in which the nucleobase is linked to the position of ribose other than Clt. Therefore isonucleoside attracted much attention owing to their chemical and enzymatic stability and potential antiviral activities5. A series of isomeric of 2',3'-dideoxynucleosides which contain a modified carbohydrate moiety have been synthesized and some of the compounds exhibited significant and selective anti-HIV activity"'. New regioisomer of AZT, AZU, BVDU and IDU have also been investigated'. Many isonucleosides syntheses have made use of epoxide opening by the a i d e anion, subsequent reduction furnishes the amine which is used to build up the heterocyclic moiety. An alternative synthesis involved the nucleophilic substitution of leaving group in the sugar ring by heterocyclic moiety under basic condition. In order to avoid the lengthy synthetic routes, we synthesized the isonucleosides using epoxide opening by the nucleobase itself in the basic c~ndition.~ The desired epoxide can be obtained from corresponding sugar.
We report on a comprehensive systematics of fusion-evaporation and/or fusionfission cross section... more We report on a comprehensive systematics of fusion-evaporation and/or fusionfission cross sections for a very large variety of systems over an energy range 4A-155A MeV. Scaled by the reaction cross sections, fusion cross sections do not show a universal behavior valid for all systems although a high degree of correlation is present when data are ordered by the system mass asymmetry. For the rather light and close to mass-symmetric systems the main characteristics of the complete and incomplete fusion excitation functions can be precisely determined. Despite an evident lack of data above 15A MeV for all heavy systems the available data suggests that geometrical effects could explain the persistence of incomplete fusion at incident energies as high as 155A MeV.
Different Liquid Drop Model mass formulae have been studied. They include a Coulomb diffuseness c... more Different Liquid Drop Model mass formulae have been studied. They include a Coulomb diffuseness correction Z 2 /A term and pairing and shell energies of the Thomas-Fermi model. The influence of the selected charge radius, the curvature energy and different forms of the Wigner term has been investigated. Their coefficients have been determined by a least square fitting procedure to 2027 experimental atomic masses. The different fits lead to a surface energy coefficient of 17-18 MeV. A large equivalent rms radius (r0 = 1.22 − 1.24 fm) or a shorter central radius may be used. A rms deviation of 0.54 MeV can be reached between the experimental and theoretical masses. The remaining differences come from the determination of the shell and pairing energies. Mass predictions are given for exotic nuclei.
EPJ manuscript No. (will be inserted by the editor) On the liquid drop model mass formulae and ch... more EPJ manuscript No. (will be inserted by the editor) On the liquid drop model mass formulae and charge radii
The efficiency of different mass formulas derived from the liquid drop model including or not the... more The efficiency of different mass formulas derived from the liquid drop model including or not the curvature energy, the Wigner term and different powers of the relative neutron excess I has been determined by a least square fitting procedure to the experimental atomic masses assuming a constant R0;charge/A 1= 3 ratio. The Wigner term and the curvature energy can be used independently to improve the accuracy of the mass formula. The different fits lead to a surface energy coefficient of around 17-18 MeV, a r sharp charge radius r0 of 1.22-1.23 fm and a proton form-factor correction to the Coulomb energy of around 0.9 MeV.
The potential energy of a deformed nucleus has been determined within a Generalized Liquid Drop M... more The potential energy of a deformed nucleus has been determined within a Generalized Liquid Drop Model taking into account the proximity energy, the microscopic corrections and compact and necked shapes. Multiple-humped potential barriers appear. A third minimum and third maximum exist in specific exit channels where one fragment is close to a magic spherical nucleus while the other one varies from oblate to prolate shapes. The heights of the fission barriers and half-lives of actinides are in agreement with the experimental results.
A great deal of research work has been undertaken in the α-clustering study since the pioneering ... more A great deal of research work has been undertaken in the α-clustering study since the pioneering discovery, half a century ago, of 12 C + 12 C molecular resonances. Our knowledge in the physics of nuclear molecules has increased considerably and nuclear clustering remains one of the most fruitful domains of nuclear physics, facing some of the greatest challenges and opportunities in the years ahead. In this work, the occurence of "exotic" shapes in light N = Z α-like nuclei is investigated. Various approaches of superdeformed and hyperdeformed bands associated with quasimolecular resonant structures are presented. Results on clustering aspects are also discussed for light neutron-rich oxygen isotopes.
Charged-particle and γ decays in 24 Mg * are investigated for excitation energies where quasimole... more Charged-particle and γ decays in 24 Mg * are investigated for excitation energies where quasimolecular resonances appear in 12 C + 12 C collisions. Various theoretical predictions for the occurrence of superdeformed and hyperdeformed bands associated with resonance structures with low spin are discussed within the measured 24 Mg * excitation energy region. The inverse kinematics reaction 24 Mg + 12 C is studied at E lab (24 Mg) = 130 MeV, an energy that enables the population of 24 Mg states decaying into 12 C + 12 C resonant breakup states. Exclusive data were collected with the Binary Reaction Spectrometer in coincidence with Euroball IV installed at the Vivitron tandem facility at Strasbourg. Specific structures with large deformation were selectively populated in binary reactions, and their associated γ decays studied. Coincident events associated with inelastic and α-transfer channels have been selected by choosing the excitation energy or the entry point via the two-body Q values. The analysis of the binary reaction channels is presented with a particular emphasis on 24 Mg-γ, 20 Ne-γ , and 16 O-γ coincidences. New information (spin and branching ratios) is deduced on high-energy states in 24 Mg and 16 O, respectively.
The interrelation of the quadrupole deformation and clusterization is investigated in the example... more The interrelation of the quadrupole deformation and clusterization is investigated in the example of the 56 Ni nucleus. The shape isomers, including superdeformed and hyperdeformed states, are obtained as stability regions of the quasidynamical U(3) symmetry based on a Nilsson calculation. Their possible binary clusterizations are investigated by considering both the consequences of the Pauli exclusion principle and the energetic preference.
The asymmetric fission barriers and the released kinetic energies in the deformation valley leadi... more The asymmetric fission barriers and the released kinetic energies in the deformation valley leading rapidly to two tangent spherical fragments have been calculated for Hg, Tb, In, Mo, and Br within the generalized liquid-drop model including the nuclear proximity energy. Results are compared to experimental data and predictions of the Yukawa plus exponential finite range liquid-drop model and the liquid-drop model. The calculated asymmetric fission barrier heights lie between the values obtained by the two other theoretical approaches.
The potential barriers governing the reactions 58 Fe + 244 Pu, 238 U + 64 Ni, and 238 U + 72 Ge h... more The potential barriers governing the reactions 58 Fe + 244 Pu, 238 U + 64 Ni, and 238 U + 72 Ge have been determined from a liquid-drop model taking into account the proximity energy, shell energies, rotational energy, and deformation of the incoming nuclei in the quasimolecular shape valley. Double-humped potential barriers appear in these entrance channels. The external saddle-point corresponds to two touching ellipsoidal nuclei when the shell and pairing effects are taken into account, while the inner barrier is due to the shell effects at the vicinity of the spherical shape of the composite system. Between them, a large potential pocket exists and persists at very high angular momenta allowing the capture of very heavy ions at high excitation energies.
The coefficients of different possible macro-microscopic mass formulae previously proposed have b... more The coefficients of different possible macro-microscopic mass formulae previously proposed have been adjusted on 2264 experimental atomic masses extracted from the AME2012 atomic mass evaluation [1] assuming N, Z ≥ 8 and the one standard deviation uncertainty on the mass lower than 150 keV. All the formulae include the volume and surface energies, the Coulomb energy, the diffuseness correction to the sharp radius Coulomb energy, the shell and pairing energies and take into account or not the curvature energy, different forms of the Wigner term, a free charge radius, the experimental equivalent rms charge radius or a fixed short central radius. Masses of 976 more exotic nuclei are extrapolated from the most accurate formula.
We systematically calculate the spontaneous fission half-lives for heavy and superheavy nuclei be... more We systematically calculate the spontaneous fission half-lives for heavy and superheavy nuclei between U and Fl isotopes. The spontaneous fission process is studied within the semi-empirical WKB approximation. The potential barrier is obtained using a generalized liquid drop model, taking into account the nuclear proximity, the mass asymmetry, the phenomenological pairing correction, and the microscopic shell correction. Macroscopic inertial-mass function has been employed for the calculation of the fission half-life. The results reproduce rather well the experimental data. Relatively long half-lives are predicted for many unknown nuclei, sufficient to detect them if synthesized in a laboratory.
The entrance and exit channels through quasimolecular shapes are compatible with the experimental... more The entrance and exit channels through quasimolecular shapes are compatible with the experimental data on fusion, light nucleus and α emissions when the proximity energy is taken into account. Analytic expressions allowing to determine rapidly this proximity energy are presented as well as formulas for the fusion barrier heights and radii and for the α emission barriers. Predictions for half-lives of exotic α emissions are proposed.
The potential barrier governing the light-nucleus emission has been determined within a generaliz... more The potential barrier governing the light-nucleus emission has been determined within a generalized liquid-drop model including the proximity effects between the light and daughter nuclei and adjusted to reproduce the experimental Q value. The partial decay half-lives have been calculated within the WKB barrier penetration probability, without introducing preformation factor. The agreement with the experimental data for the 14 C, 20 O, 23 F, 24−26 Ne, 28−30 Mg and 32 Si emission is good. Predictions for other possible decays are presented meeting two criteria: partial half-life 10 30 s and branching ratio relative to α emission 10 −24. An analytic formula is proposed for the half-life of the light-nucleus decay.
Longitudinal ternary and binary fission barriers of 36 Ar, 56 Ni and 252 Cf nuclei have been dete... more Longitudinal ternary and binary fission barriers of 36 Ar, 56 Ni and 252 Cf nuclei have been determined within a rotational liquid drop model taking into account the nuclear proximity energy. For the light nuclei the heights of the ternary fission barriers become competitive with the binary ones at high angular momenta since the maximum lies at an outer position and has a much higher moment of inertia.
Different Liquid Drop Model mass formulae have been studied. They include a Coulomb diffuseness c... more Different Liquid Drop Model mass formulae have been studied. They include a Coulomb diffuseness correction Z 2 /A term and pairing and shell energies of the Thomas-Fermi model. The influence of the selected charge radius, the curvature energy and different forms of the Wigner term has been investigated. Their coefficients have been determined by a least square fitting procedure to 2027 experimental atomic masses. The different fits lead to a surface energy coefficient of 17-18 MeV. A large equivalent rms radius (r0 = 1.22 − 1.24 fm) or a shorter central radius may be used. A rms deviation of 0.54 MeV can be reached between the experimental and theoretical masses. The remaining differences come from the determination of the shell and pairing energies. Mass predictions are given for exotic nuclei.
We report on a systematics of fusion cross section data at energies above the reaction threshold ... more We report on a systematics of fusion cross section data at energies above the reaction threshold to those of disappearance of fusion process. By an appropriate scaling of both cross sections and energy, a fusion excitation function common to all the data points is established. A universal description of the fusion excitation function relying on basic nuclear concepts is proposed and its dependence on the reaction cross section used for the cross section normalization is discussed.
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Papers by Guy Royer