Effect of selenite on 86Rb uptake by rat lens
International Nuclear Information System (INIS)
The effect was observed in vitro of selenite on the uptake of 86Rb by the lens in two weeks old and adult rats. Also measured was the uptake of 86Rb by the lens in vitro in 30-days old rats with cataracts induced by the administration of selenite at day 14 after birth and in control animals of the same age. Selenite in a concentration of 0.4 mM and more caused an insignificant decrease in 86Rb uptake by the lens in adult rats while in the lens of young rats the uptake decreased significantly already at concentrations lower by two orders. Lenses with cataracts took up significantly less 86Rb than transparent lenses; body weight, the weight of the fresh lens and its dry mass decreased while the water content in the lens was higher as compared with control groups. (author). 2 tabs., 26 refs
Loss of receptor-mediated 86Rb efflux from pig aortic endothelial cells in culture.
Ager, A.; Martin, W
1983-01-01
The responsiveness of freshly-isolated and subcultured pig aortic endothelial cells to adenosine triphosphate (ATP), bradykinin and ionophore A23187 was compared by monitoring agonist-induced 86Rb efflux. ATP, bradykinin and ionophore A23187 stimulated 86Rb efflux from freshly-isolated cells. ATP and bradykinin, which act via specific receptors, were less effective at inducing 86Rb efflux from subcultured cells but ionophore A23187 was as effective on subcultured as on freshly-isolated cells....
86Rb Distribution in the Lung of the Rabbit with Pneumothorax
International Nuclear Information System (INIS)
86Rb uptake of some organs and tissues, eg. both lungs, both renal cortices. small intestine, liver and skeletal muscle were studied in the control and the rabbit subjected to pneumothorax. 86Rb in the form of chloride mixed with physiological saline was intravenously injected. The doses were 100 μc for a rabbit. The rabbits were sacrificed at intervals of 10, 20, 40, and 60 seconds after the injection of 86Rb, by the injection of saturated KCI solution. After scarification, the organ and tissue sample were quickly removed. 86Rb uptake in gm of the organs and tissues were measured. On the basis of uptake value, administered doses and body weight, % dose/gm tissues per 200 gm body weight was calculated. Followings were the results: 1. Pneumothorax resulted in a marked elevation in 86Rb uptake value of collapsed lung and returned to normal level lately. 2. Contralateral lung of pneumothorax also showed marked elevation in 86Rb uptake value and recovered to normal level. 3. Initial 86Rb uptake value of liver, small intestine of the rabbit with pneumothorax showed some elevation as compared to control, but that of late stage were similar with control. 4. Local blood flow determination by means of 86Rb uptake were inadequate in the collapsed lung of pneumothorax. 5. It was suggested that the mechanism for the initial elevation of 86Rb uptake value in each organs and tissue were different from each other.
Leiurus quinquestriatus venom inhibits BRL 34915-induced 86Rb+ efflux from the rat portal vein
International Nuclear Information System (INIS)
The effect of the crude venom of the Israeli scorpion Leiurus quinquestriatus hebraeus on the 86Rb+ efflux stimulated by the K+ channel opener BRL 34915 in the rat portal vein was examined. Applied alone, the venom greatly increased the spontaneous mechanical activity of and the concomitant 86Rb+ efflux from the vessel. When the excitability of the vein was suppressed by the dihydropyridine calcium antagonist, PN 200-110, the 86Rb+ efflux stimulated by BRL 34915 could be shown to be inhibited by the venom. From the concentration dependence of this inhibition an IC50 value of 0.17 +/- 0.01 mg/ml was estimated. This venom is thus the most potent blocker of BRL 34915-evoked 86Rb+ efflux reported so far. 17 references, 2 figures
Burn-up cross sections of 51Cr, 59Fe, 65Zn, 86Rb, 103Ru
International Nuclear Information System (INIS)
Targets of Cr, Fe, Zn, Rb, and Ru were irradiated in the hydraulic tube of the Oak Ridge HFIR reactor at a neutron flux of 2.6 x 1015 n/cm2sec for 1 day and 20 days. The reactor burn-up cross sections (in barns) of the radioactive product nuclides are: 51Cr, 59Fe, 65Zn, 60 +- 30; 86Rb, 103Ru, <20
de-Allie, F. A.; Bolsover, S. R.; Nowicky, A. V.; Strong, P N
1996-01-01
1. The pharmacological characteristics of a putative Ca2+ activated K+ channel (IKCa channel) in rat glioma C6 cells were studied in the presence of the Ca2+ ionophore, ionomycin and various K+ channel blockers, 86Rb+ being used as a radioisotopic tracer for K+. 2. The resting 86Rb+ influx into C6 cells was 318 +/- 20 pmol s-1. The threshold for ionomycin activation of 86Rb+ influx was approx. 100 nM. At ionomycin concentrations above the activation threshold, the initial rate of 86Rb+ influx...
Review of metastable states in heavy nuclei
Dracoulis, G. D.; Walker, P. M.; Kondev, F. G.
2016-07-01
The structure of nuclear isomeric states is reviewed in the context of their role in contemporary nuclear physics research. Emphasis is given to high-spin isomers in heavy nuclei, with A≳ 150 . The possibility to exploit isomers to study some of the most exotic nuclei is a recurring theme. In spherical nuclei, the role of octupole collectivity is discussed in detail, while in deformed nuclei the limitations of the K quantum number are addressed. Isomer targets and isomer beams are considered, along with applications related to energy storage, astrophysics, medicine, and experimental advances.
Energy Technology Data Exchange (ETDEWEB)
Kennedy, R.H.; Seifen, E.
1989-01-01
Previous work in anesthetized rats has demonstrated that the sensitivity to cardiotoxic actions of cardiotonic steroids is increased in senescence, and studies in crude homogenates and partially purified membrane preparations have suggested that this altered responsiveness is related to an aging-associated reduction in the sarcolemmal content of Na,K-adenosine triphosphatase. This decrease in Na,K-adenosine triphosphatase could enhance the sensitivity to digitalis-like compounds by reducing the reserve capacity of the Na+-pump and thus the extent of digitalis-induced pump inhibition required before the onset of toxicity. Current experiments examined dose-dependent actions of digoxin in atrial muscle isolated from 3-, 12- and 24- to 25-month-old rats and determined if alterations in responsiveness correlated with changes in ouabain-sensitive 86Rb+ uptake rate, an estimate of Na+-pump activity. Atrial preparations from aged rats were more sensitive to the cardiotoxic actions of digoxin; however, the inotropic efficacy before the onset of toxicity was not affected by age. Both 1) the maximum attainable ouabain-sensitive 86Rb+ uptake rate and 2) the difference between maximum uptake rate and that monitored in preparations stimulated at 4.0 Hz decreased progressively with age. These results indicate that atrial muscle from aged rats is more sensitive to direct toxic effects of digoxin and suggest that this lower tolerance is mediated, at least in part, by a reduction in Na+-pump reserve capacity.
Energy Technology Data Exchange (ETDEWEB)
Franzen, L.; Littbrand, B.; Henriksson, R. (Univ. Hospital, Dept. of Oncology, Umeaa (Sweden)); Sundstroem, S. (Univ. Hospital, Dept. of Histology and Cell Biology, Umeaa (Sweden)); Karlsson, M. (Univ. Hospital, Dept. of Radiation Physics, Umeaa (Sweden)); Gustafsson, H. (Univ. Hospital, Dept. of Oto-Laryngology, Umeaa (Sweden))
1992-01-01
The effects of fractionated irradiation on the electrolyte fluid secretion from rat parotid gland were studied. Secretion was measured as noradrenaline stimulated potassium efflux in vitro with [sup 86]Rb[sup +] as tracer for potassium. The irradiation was delivered either as a five-day schedule (total dose 20, 25, 30, 35, 40, 45 Gy) or a two-day schedule (total dose 24, 32 Gy). The noradrenaline stimulated efflux was decreased in comparison with contralateral controls 10 days after the last irradiation. The effect was dose-dependent. Based on the data available, [alpha]/[beta] ratio of the used system was calculated to about 20 Gy, which corresponds to other results regarding early radiation effects. (orig.).
International Nuclear Information System (INIS)
Greenhouse and laboratory studies were conducted on an acid soil in order to evaluate the role of two crop residues i.e. paddy and wheat along with farmyard manure on potassium kinetics and its availability in the potato-garlic sequence using tracer 86Rb. Under rapid equilibrium, application of crop residues of paddy, wheat straw and FYM were able to enhance soil pH and organic carbon content. In addition, their application helped in enhancing soil K availability indices like water soluble, available and non-exchangeable -K. This was further augmented by the Q/I studies using 86Rb where application of organic residues helped in lowering the potassium buffering capacity of the soil. Greenhouse study supplemented the results obtained from laboratory study where application of crop residues/FYM were able to improve the potato yield significantly and maintained higher concentration of K in potato leaf at early growth stages. A significant correlation was obtained between leaf K and haulms-K with that of 86Rb activities in potato leaf at 35 days and 86Rb absorbed in the haulms, respectively. Residues/ FYM and PK application to potato left sufficient residual effect on succeeding garlic crop. In potato-garlic sequence, K recovery was highest with FYM while N and P recoveries were higher with wheat residues. The nutrient recoveries with PK application followed law of diminishing returns. (author)
Energy Technology Data Exchange (ETDEWEB)
Turaihi, K.; Khokher, M.A.; Barradas, M.A.; Mikhailidis, D.P.; Dandona, P. (Royal Free Hospital and School of Medicine, London (England))
1989-08-01
Although active transport of potassium into human platelets has been demonstrated previously, there is hitherto no evidence that human platelets have an ouabain-inhibitable Na-K ATPase in their membrane. The present study demonstrates active rubidium (used as an index of potassium influx), {sup 86}Rb(K), influx into platelets, inhibitable by ouabain, and also demonstrates the presence of specific ({sup 3}H)ouabain binding by the human platelet. This {sup 86}Rb(K) influx was stimulated by adrenaline, isoprenaline, and salbutamol, but noradrenaline caused a mild inhibition. Active {sup 86}Rb(K) influx by platelets was inhibited markedly by timolol, mildly by atenolol, but not by phentolamine. Therefore, active {sup 86}Rb(K) influx in human platelets is enhanced by stimulation of beta adrenoceptors of the beta 2 subtype. The platelet may therefore replace the leukocyte in future studies of Na-K ATPase activity. This would be a considerable advantage in view of the ease and rapidity of preparation of platelets.
Transitions between compound states of spherical nuclei
International Nuclear Information System (INIS)
Wigner's statistical matrices are used to study the average reduced g widths and their dispersion for g transitions from a compound state c to another state f, with a lower excitation energy but of arbitrary complexity, for spherical nuclei. It is found that the Porter--Thomas distribution holds for the g widths for all cases of practical interest. In g transitions between compound states c and c' with E/sub g/< or =2 MeV, the most important transitions are M1 transitions involving the major many-quasiparticle components of state c and E1 transitions involving the minor components of state c. It is shown that the strength functions predicted by the various theories for M1 and E1 transitions between compound states with E/sub g/< or =2 MeV are similar. Preference is assigned to the M1-transition version because of experimental results on (n,ga) reactions with thermal and resonance neutrons
Energy Technology Data Exchange (ETDEWEB)
Andersen, G.Oe.; Enger, M.; Skomedal, T.; Osnes, J.B. [Univ. of Oslo, Dept. of Pharmacology (Norway)
1996-10-01
The aim of the present study was to establish a concentration-response relationship for the {alpha}{sub 1}-adrenoceptor mediated increase of{sup 86}Rb{sup +} efflux, and to characterize the sensitivity of this response to the selective {alpha}{sub 1}-adrenoceptor antagonist prazosin. Isolated rat hearts were perfused retrogradely at constant flow and at 31 deg. Timolol (10{sup -}26 mol/l) was used to block {beta}-adrenoceptors. After a loading period with {sup 86}Rb{sup +} and 55 min. washout, the hearts were exposed to phenylephrine in a concentration range from 3x10{sup -8} mol/l to 10{sup -4} mol/l. Control experiments comparing the effects of {alpha}{sub 1}-adrenoceptor stimulation on {sup 86}Rb{sup +} efflux and {sup 42}K{sup +} efflux were performed. {alpha}{sub 1}-Adrenoceptor stimulation increased the {sup 86}Rb{sup +} efflux with a pD{sub 2}=6.35{+-}0.20 (mean{+-}S.E.M.) The maximal response to phenylephrine was 22.5{+-}2.0% (mean{+-}S.E.M.) of the control values. The concentration-response curve was shifted to higher concentration of agonist in the presence of the {alpha}{sub 1}-adrenoceptor antagonist prazosin (3x10{sup -10} mol/l). The calculated inhibition constant for prazosin was 6.1x10{sup -11} mol/l. {sup 86}Rb{sup +} was found to be a suitable K{sup +} analogue in the study of relative changes in K{sup +} efflux concentration-dependently. A high sensitivity to prazosin confirmed the involvement of the {alpha}{sub 1}-adrenoceptor population. (au) 37 refs.
Ground State Properties of Neutron Magic Nuclei
Saxena, G
2016-01-01
A systematic study of the ground state properties of the entire chains of even even neutron magic nuclei represented by isotones of traditional neutron magic numbers N = 8, 20, 40, 50, 82 and 126 has been carried out using relativistic mean field (rmf) plus Bardeen Cooper Schrieffer (BCS) approach. Our present investigation includes deformation, binding energy, two proton separation energy, single particle energy, rms radii along with proton and neutron density profiles, etc. Several of these results are compared with the results calculated using non relativistic approach (Skyrme Hartree Fock method) along with available experimental data and indeed they are found with excellent agreement. In addition, the possible locations of the proton and neutron drip lines, the (Z,N) values for the new shell closures, disappearance of traditional shell closures as suggested by the detailed analyzes of results are also discussed in detail.
Density Functional Theory studies of cluster states in nuclei
Ebran, J P; Niksic, T; Vretenar, D
2014-01-01
The framework of nuclear energy density functionals is applied to a study of the formation and evolution of cluster states in nuclei. The relativistic functional DD-ME2 is used in triaxial and reflection-asymmetric relativistic Hartree-Bogoliubov calculations of relatively light $N = Z$ and neutron-rich nuclei. The role of deformation and degeneracy of single-nucleon states in the formation of clusters is analysed, and interesting cluster structures are predicted in excited configurations of Be, C, O, Ne, Mg, Si, S, Ar and Ca $N = Z$ nuclei. Cluster phenomena in neutron-rich nuclei are discussed, and it is shown that in neutron-rich Be and C nuclei cluster states occur as a result of molecular bonding of $\\alpha$-particles by the excess neutrons, and also that proton covalent bonding can occur in $^{10}$C.
Directory of Open Access Journals (Sweden)
Minkov N.
2016-01-01
Full Text Available We study the effects of quadrupole-octupole deformations on the energy and magnetic properties of high-K isomeric states in even-even heavy and superheavy nuclei. The neutron two-quasiparticle (2qp isomeric energies and magnetic dipole moments are calculated within a deformed shell model with the Bardeen-Cooper- Schrieffer (BCS pairing interaction over a wide range of quadrupole and octupole deformations. We found that in most cases the magnetic moments exhibit a pronounced sensitivity to the octupole deformation, while the 2qp energies indicate regions of nuclei in which the presence of high-K isomeric states may be associated with the presence of octupole softness or even with octupole deformation. In the present work we also examine the influence of the BCS pairing strength on the energy of the blocked isomer configuration. We show that the formation of 2qp energy minima in the space of quadrupole-octupole and eventually higher multipolarity deformations is a subtle effect depending on nuclear pairing correlations.
Energy Technology Data Exchange (ETDEWEB)
Vinge, E.; Helgesen-Rosendal, S.; Baeckstroem, T.
1988-01-01
Progesterone and some derivatives were tested in a radioimmunoassay (RIA) of digoxin and in a bioassay measuring the /sup 86/Rb-uptake into red blood cells as in index of Na/sup +/, K/sup +/-ATPase activity. The digitalis-like activity of the hormones was compared with that found in chromatographic fractions of material extracted from the urines of pregnant women at term. Progesterone at concentrations > 10/sup -6/ fM cross-reacted in the RIA, and at 10/sup -3/ M it decreased /sup 86/Rb-uptake by 18%. The anaesthetic progesterone derivates 5..cap alpha..-pregnance-3..cap alpha..-ol-20-one and 5..cap alpha..-pregnane-3,20-dione crossreacted to a lesser degree in the RIA and lacked effect in the bioassay. Similar results were obtained with pregnandiol-glucuronide, the major urinary metabolite of progesterone. In contrast, several fractions of the urinary material had significant effects in both assays. It is concluded that the digitalis-like activity of progesterone is not coupled to properties associated with its anaesthetic effects. Furthermore, although progesterone may account for a part of the endogenous digoxin-like substances in serum of neonates and pregnant women, neither progesterone proper nor pregnandiol-glucuronide explains the great amount of digoxin-like substances found in the urines.
Rotational states in deformed nuclei: An analytic approach
Bentz, W; Enders, J; Richter, A; Wambach, J
2011-01-01
The consequences of the spontaneous breaking of rotational symmetry are investigated in a field theory model for deformed nuclei, based on simple separable interactions. The crucial role of the Ward-Takahashi identities to describe the rotational states is emphasized. We show explicitly how the rotor picture emerges from the isoscalar Goldstone modes, and how the two-rotor model emerges from the isovector scissors modes. As an application of the formalism, we discuss the M1 sum rules in deformed nuclei, and make connection to empirical information.
Deeply bound kaonic states in nuclei
Institute of Scientific and Technical Information of China (English)
LI Yi-He; WU Shi-Shu
2009-01-01
Using a new phenomenological (K)N interaction which reproduces A(1405) as an I = 0 bound state of (K)N, we have investigated K- -3 He(T = 0) and K- -4 He(T = 1/2) within the framework of the Brueckner-Hartree-Fock(BHF) theory. Our calculations show that the above kaonic nuclear systems are both deeply bound. The binding energy BK- is 124.4 MeV(94.1 MeV) and the width Γ is 11.8 MeV(25.8 MeV) for K- -3 He(T = 0)(K- -4 He(T= 1/2)).
Situation with collective two-phonon states in deformed nuclei
International Nuclear Information System (INIS)
Within the quasiparticle-phonon nuclear model with the operators of phonons depending on the sign of the angular momentum projection, the Pauli principle is taken into account in the two-phonon components of the wave functions. The centroid energies of the collective two-phonon states in even-even deformed nuclei are calculated. It is shown that the inclusion of the Pauli principle leads to their shift by 1-3 MeV towards high energies. The shifts of three-phonon poles due to the Pauli principle are calculated in the three-phonon components of the wave functions. The collective two-phonon states, the centroid energies of which are 3-5 MeV, are expected to be strongly fragmented. The conclusion is confirmed that the collective two-phonon states should not exist in deformed nuclei. The situation in 168Er and in the 228Th isotopes is analysed
Isotopic dependence of isomeric states in heavy nuclei
International Nuclear Information System (INIS)
High-spin K-isomer states, which are usually assumed as two quasiparticle high-spin configurations states, were observed in heavy nuclei 250,256Fm, 252,254No, 266Hs and 270,271Ds. In order to calculate the energies of 2qp isomer states in even-even nuclei, the two-center shell model is used for finding the single-particle levels at the ground state of nucleus. The shape parameterization used in this model effectively includes many even multipolarities. The dependence of the parameters of Is and I2 terms on A and N - Z were modified for the correct description of the ground state spins of odd actinides. The microscopical corrections and quadrupole parameters of deformation calculated with the two-center shell model are close to those obtained with the microscopic-macroscopic approaches of P. Moller et al. and A.Sobiczewski et al. The calculated values of Qa are in reasonable agreement with measured values. The calculated two-quasiparticle energies are in good agreement with the available experimental data. In the even isotope chains of Fm and No the calculated E2qp for high spin K-isomer states are minimal for 250Fm and 252No. In 242,244Fm the K-isomer states with K ≥ 6 are above 1.38 MeV that is larger than the energies of the K-isomer states in 252,254No. In order to observe these states in the neutron-deficient Fm isotopes, one should produce these isotopes with the cross sections similar to those for the nuclei 252,254No. Calculating the potential energy surface near the ground state, one can not exclude the existence of shallow potential minima which can be related to the shape isomers. The possibility of existence of these minima is discussed within the microscopic-macroscopic model. We found the indications for the low-lying shape isomers in 264,266Sg and 268,270Hs The alpha-decay between the isomer states and between the ground states can have similar properties that shields the observation of isomeric states. The population of the isomer states in the
Separable interactions and excited states in open-shell nuclei
International Nuclear Information System (INIS)
The relevant matrix elements of the Hamiltonian for a RPA description of collective states in open-shell nuclei are determined. For separable interactions it is found necessary to include the particle-particle and particle-hole interactions simultaneously. The energy-weighted sum rule for the electromagnetic operator (with angular momentum I) is greatly reduced by the use of the pairing interaction with the same angular momentum. (author)
Critical Points in Nuclei and Interacting Boson Model Intrinsic States
Ginocchio, J N; Ginocchio, Joseph N.
2003-01-01
We consider properties of critical points in the interacting boson model, corresponding to flat-bottomed potentials as encountered in a second-order phase transition between spherical and deformed $\\gamma$-unstable nuclei. We show that intrinsic states with an effective $\\beta$-deformation reproduce the dynamics of the underlying non-rigid shapes. The effective deformation can be determined from the the global minimum of the energy surface after projection onto the appropriate symmetry. States of fixed $N$ and good O(5) symmetry projected from these intrinsic states provide good analytic estimates to the exact eigenstates, energies and quadrupole transition rates at the critical point.
Cluster structure in highly-excited states of light nuclei
International Nuclear Information System (INIS)
The cluster structure in the highly-excited states of light nuclei are investigated using the multi-cluster model. For this purpose, we propose a developed treatment method of the multi-cluster model. The method consists of two parts: One is a systematic construction method of the multi-cluster Pauli-allowed states. Another is a truncation method of the large model space of the multi-cluster system. We show that we can easily solve the equation of the orthogonality condition model (OCM) for complex multi-cluster systems by the use of the method. We apply the multi-cluster models 3α, 4α, 12C + 2α and 16O + 2α to 12C, 16O, 20Ne and 24Mg, respectively. As shown in the Ikeda diagram, these models open a very interesting problem not only of the cluster structure in the highly-excited states of those nuclei but also of the structure change between different cluster structures. We show a typical example of the 16O + 2α model for 24Mg ; 1) many excited states with the 20Ne-α cluster structure are obtained at excitation energies above 10 MeV, 2) the 16O-8Be cluster states are obtained at the energy region higher than 20 MeV, and 3) the very interesting states with the α-16O-α linear-chain-like structure are predicted at about 20 MeV excitation energy. (author)
The ground state of deformed nuclei as a boson condensate
International Nuclear Information System (INIS)
It is shown that the ground state of deformed nuclei can be considered as a condensate of bosons that do not have a well-defined angular momentum. Values for the quadrupole mome-t and the particle number that are very close to the values obtained using the full boson wave function are obtained by retaining only the s- and d-parts of the boson wave function. By comparing with the many-shell (realistic) situation we found the limitations of the single-shell calculations. (orig.)
Gamma transitions between compound states in spherical nuclei
International Nuclear Information System (INIS)
Average values of the reduced γ widths and their dispersions are investigated, basing on the Wigner statistical matrix method, for γ transitions from a compound state c into a less-energy excited state f of an arbitrary complexity in spherical nuclei. It is shown that in all the cases of practical interest the Porter-Thomas distribution is valid for the γ widths. It is found that in the γ transitions between compound states c and c' with Esub(γ) <= 2 MeV the dominating role is played by the M1 transitions due to the main multiquasiparticle states of c, and by the E1 transitions, due to small components of the state c. In framework of the existent theoretical schemes it is shown that the strength functions of the M1 and E1 transitions between the compound states with Esub(γ) <2 MeV are close. It is deduced thet the variant of the M1 transitions is preferable in view of the experimental results on the (n, γα) reactions induced by thermal and resonance neutrons
Equation of state of hot nuclei before break-up
International Nuclear Information System (INIS)
Following the method developed by the authors, recently, the equation of state of hot nuclei (238U* in concrete) before break-up was investigated numerically. The isotherms are drawn in the plane of the general pressure P versus volume VRT. They are similar to those of Van der Waals gas. The critical temperature of phase transition should correspond to the isotherm with one truning point only. It turns out that the data of mas yield distribution can be reproduced by many pairs of parameters T and VRT (freeze-out temperature and freezeout volume) varying in certain range. For each isotherm (each T), the data are always best reproduced by the value of VRT located at the maximum general pressure within two phases coexistence region
Alternating-parity collective states of yrast and nonyrast bands in lanthanide and actinide nuclei
International Nuclear Information System (INIS)
Excited collective states of even-even nuclei featuring quadrupole and octupole deformations are studied within a nonadiabatic collective model with a Gaussian potential energy. Rotational states of the yrast band and vibrational-rotational states of nonyrast bands are considered in detail. The energies of alternating-parity excited states of the yrast band in the 164Er, 220Ra, and 224Th nuclei; the yrast and first nonyrast bands in the 154Sm and 160Gd nuclei; and the yrast, first nonyrast, and second nonyrast bands in the 224Ra and 240Pu nuclei are described well on the basis of the proposed model
Collective and single particle states in medium mass vibrational nuclei
International Nuclear Information System (INIS)
The particle-core coupling model has been employed to describe the low lying nuclear excitations in the vibrational odd-A nuclei. In the frame of this model the following observables were calculated: excitation energies, spin and parity quantum numbers, electric quadrupole moments, magnetic dipole moments and reduced transition probabilities. Two computer codes were employed. The first one, PCOREC, diagonalized the Hamiltonian providing the eigenvectors and eigenvalues. The second one, PCORECTR, starts from the eigenvector computer by the first program and computes the observables which are compared we results of experiments. A good description of the experimental data has been obtained for the 133 Sb, 123 Sb and 125 Sb nuclei. (authors)
Giant isoscalar monopole states in light even-even nuclei
International Nuclear Information System (INIS)
An attempt is made to set experimental limits on the centroid energy of isoscalar monopole strength in light nuclei, by making use of sum rules and measured EO transition rates. The model-dependence of the non-energy-weighted sum rule is tested in 16O and a reasonable estimate of the centroid energy obtained. Comparison with a simple macroscopic model allows the extraction of the nuclear compressibility. Experimental and theoretical consequences of these results are briefly discussed. (author)
Torres, D A
2016-01-01
The experimental study of magnetic moments for nuclear states near the ground state, $I \\ge 2$, provides a powerful tool to test nuclear structure models. The study of magnetic moments in nuclei far away from the stability line is the next frontier in such studies. Two techniques have been utilized to populated low-spin states in radioactive nuclei: coulomb excitation reactions using radioactive nuclei, and the transfer of $\\alpha$ particles to stable beams to populate low spin states in radioactive nuclei. A presentations of these two techniques, along with the experimental challenges presented for future uses with nuclei far away from the stability line, will be presented.
Candidates for Long Lived High-K Ground States in Superheavy Nuclei
Jachimowicz, P; Skalski, J
2015-01-01
On the basis of systematic calculations for 1364 heavy and superheavy nuclei, including odd-systems, we have found a few candidates for high-K ground states in superheavy nuclei. The macroscopic-microscopic model based on the deformed Woods-Saxon single particle potential which we use offers a reasonable description of SH systems, including known: nuclear masses, $Q_{\\alpha}$-values, fission barriers, ground state deformations, super- and hyper-deformed minima in the heaviest nuclei. %For odd and odd-odd systems, both ways of including pairing correlations, % blocking and the quasi-particle method, have been applied. Exceptionally untypical high-K intruder contents of the g.s. found for some nuclei accompanied by a sizable excitation of the parent configuration in daughter suggest a dramatic hindrance of the $\\alpha$-decay. Multidimensional hyper-cube configuration - constrained calculations of the Potential Energy Surfaces (PES's) for one especially promising candidate, $^{272}$ Mt, shows a $\\backsimeq$ 6 Me...
New high spin states and isomers in the {sup 208}Pb and {sup 207}Pb nuclei
Energy Technology Data Exchange (ETDEWEB)
Broda, R.; Wrzesinski, J.; Pawlat, T. [and others
1996-12-31
The two most prominent examples of the heavy doubly closed shell (DCS) nuclei, {sup 208}Pb and {sup 132}Sn, are not accessible by conventional heavy-ion fusion processes populating high-spin states. This experimental difficulty obscured for a long time the investigation of yrast high-spin states in both DCS and neighboring nuclei and consequently restricted the study of the shell model in its most attractive regions. Recent technical development of multidetector gamma arrays opened new ways to exploit more complex nuclear processes which populate the nuclei of interest with suitable yields for gamma spectroscopy and involve population of moderately high spin states. This new possibility extended the range of accessible spin values and is a promising way to reach new yrast states. Some of these states are expected to be of high configurational purity and can be a source of important shell model parameters which possibly can be used later to check the validity of the spherical shell model description at yet higher spin and higher excitation energy. The nuclei in the closest vicinity of {sup 132}Sn are produced in spontaneous fission and states with spin values up to I=14 can be reached in fission gamma spectroscopy studies with the presently achieved sensitivity of gamma arrays. New results on yrast states in the {sup 134}Te and {sup 135}I nuclei populated in fission of the {sup 248}Cm presented at this conference illustrate such application of the resolving power offered by modern gamma techniques.
Energy Technology Data Exchange (ETDEWEB)
Furusawa, Shun; Yamada, Shoichi [Advanced Research Institute for Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555 (Japan); Sumiyoshi, Kohsuke [Numazu College of Technology, Ooka 3600, Numazu, Shizuoka 410-8501 (Japan); Suzuki, Hideyuki, E-mail: furusawa@heap.phys.waseda.ac.jp [Faculty of Science and Technology, Tokyo University of Science, Yamazaki 2641, Noda, Chiba 278-8510 (Japan)
2013-08-01
We construct new equations of state for baryons at subnuclear densities for the use in core-collapse simulations of massive stars. The abundance of various nuclei is obtained together with thermodynamic quantities. A model free energy is constructed, based on the relativistic mean field theory for nucleons and the mass formula for nuclei with the proton number up to {approx}1000. The formulation is an extension of the previous model, in which we adopted the liquid drop model to all nuclei under the nuclear statistical equilibrium. We reformulate the new liquid drop model so that the temperature dependences of bulk energies could be taken into account. Furthermore, we extend the region in the nuclear chart, in which shell effects are included, by using theoretical mass data in addition to experimental ones. We also adopt a quantum-theoretical mass evaluation of light nuclei, which incorporates the Pauli- and self-energy shifts that are not included in the ordinary liquid drop model. The pasta phases for heavy nuclei are taken into account in the same way as in the previous model. We find that the abundances of heavy nuclei are modified by the shell effects of nuclei and temperature dependence of bulk energies. These changes may have an important effect on the rates of electron captures and coherent neutrino scatterings on nuclei in supernova cores. The abundances of light nuclei are also modified by the new mass evaluation, which may affect the heating and cooling rates of supernova cores and shocked envelopes.
F-SPIN PURITY OF 2+1 STATES IN EVEN-EVEN NUCLEI
SCHOLTEN, O; CASTEN, RF
1993-01-01
A procedure is proposed by which upper limits to the F-spin purity of 2+1 states in even-even nuclei can be estimated by an analysis of experimental g-factors. The procedure, applied to 17 nuclei with 46 less-than-or-equal-to Z less-than-or-equal-to 78, showed that F
The ground state of medium-heavy nuclei with non central forces
Fabrocini, A
1997-01-01
We study microscopically the ground state properties of 16O and 40Ca nuclei within correlated basis function theory. A truncated version of the realistic Urbana v14 (U14) potential, without momentum dependent terms, is adopted with state dependent correlations having spin, isospin and tensor components. Fermi hypernetted chain integral equations and single operator chain approximation are used to evaluate one- and two-body densities and ground state energy. The results are in good agreement with the available variational MonteCarlo data, providing a first substantial check for the accuracy of the cluster expansion method with state dependent correlations. The finite nuclei treatment of non central interactions and correlations has, at least, the same level of accuracy as in infinite nuclear matter. The binding energy for the full U14+TNI interaction is computed, addressing its small momentum dependent contributions in local density approximation. The nuclei are underbound by about 1 MeV per nucleon. Further e...
State-dependent Jastrow correlation functions for $^{4}He$ nuclei
Guardiola, R
1998-01-01
We calculate the ground-state energy for the nucleus 4He with V4 nucleon interactions, making use of a Jastrow description of the corresponding wavefunction with state-dependent correlation factors. The effect related to the state dependence of the correlation is quite important, lowering the upper bound for the ground-state energy by some 2 MeV.
Manifestation of cluster effects in collective octupole and superdeformed states of heavy nuclei.
Shneidman, T. M.; Adamian, G. G.; Antonenko, N. V.; Jolos, R. V.
2016-06-01
The effects of reflection-asymmetric deformation on the properties of the low-lying negative-parity collective states and superdeformed states of heavy nuclei are analyzed basing on dinuclear model. The results of consideration of the alternating parity bands in actinides and the superdeformed bands in 60Zn, Pb and Hg isotopes are discussed.
Constraints on the Skyrme Equations of State from Properties of Doubly Magic Nuclei
Brown, B.Alex
2013-01-01
I use properties of doubly-magic nuclei to constrain nuclear matter and neutron matter equations of state. I conclude that the data determined the value of the neutron equation of state and the symmetry energy near a density of $\\rho_{on}$ = 0.10 nucleons/fm$^{3}$. The slope at that point is constrained by the value of the neutron skin.
Alpha cluster states and molecular orbitals in sd-shell nuclei
Energy Technology Data Exchange (ETDEWEB)
Kimura, M. [Creative Research Institution Sousei Research Department, Hokkaido University, Sapporo 001-0021 (Japan); Furutachi, N. [Meme Media Laboratory, Hokkaido University, Sapporo 060-8628 (Japan); Kanada-En' yo, Y. [Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502 (Japan)
2010-03-01
The alpha-clustering and molecular-orbitals of {sup 22}Ne and F isotopes are investigated based on antisymmetrized molecular dynamics (AMD). The observed candidates for the alpha cluster state of {sup 22}Ne are understood as the molecular-orbital states and alpha+{sup 18}O di-nuclei states. The presence of the molecular-orbital states in the O and F isotopes and the drastic reduction of their excitation energy near the neutron-drip line are predicted.
Ground State Properties of Superheavy Nuclei in Macroscopic-Microscopic Model
Institute of Scientific and Technical Information of China (English)
ZHI Qi-Jun; REN Zhong-Zhou; ZHANG Xiao-Ping; ZHENG Qiang
2008-01-01
The ground state properties of superheavy nuclei are systematically calculated by the macroscopic-microscopic (MM) model with the Nilsson potential The calculations well produced the ground state binding energies,a-decay energies,and half lives of superheavy nuclei.The calculated results are systematically compared with available experimental data.The calculated results are also compared with theoretical results from other MM models and from relativistic mean-field model.The calculations and comparisons show that the MM model is reliable in superheavy region and that the MM model results are not very sensitive to the choice of microscopic single-particle potential.
Institute of Scientific and Technical Information of China (English)
E.Javadimanesh; H.Hassanabadi; A.A.Rajabi; H.Rahimov; S.Zarrinkamar
2012-01-01
We study the half-lives of some nuclei via the alpha-decay process from ground state to ground state. To go through the problem, we have considered a potential model with Yukawa proximity potential and have thereby calculated the half-lives. The comparison with the existing data is motivating.
International Nuclear Information System (INIS)
It has been shown that IAS, DIAS, CS, and DCS can simultaneously have n-n, n-p, and p-p halo components in their wave functions. Differences in halo structure of the excited and ground states can result in the formation of isomers (halo-isomers). Both the Borromean and tango halo types can be observed for n-p configurations of atomic nuclei. The structure of the ground and excited states with different isospin quantum number in halo like nuclei is discussed. B(Mλ) and B(Eλ) for γ-transitions in 6,7,8Li, 8,9,10Be, 8,10,11B, 10,11,12,13,14C, 13,14,15,16,17N, 15,16,17,19O, and 17F are analyzed. Special attention is given to nuclei whose ground state does not exhibit halo structure but the excited state may have one
State-dependent pairing fields in rotating nuclei
International Nuclear Information System (INIS)
In the present thesis the properties of state-dependent pairing and its influence on the nuclear rotation were studied. For this the HFBC equations were solved by a new developed method in a model with a Nilsson operator for the single-particle part and the surface-delta interaction for the generation of the self-consistently calculated pairing fields. The agreement with the experimental data was improved in all considered cases by regarding the higher multipoles (state-dependent pairing). (orig./HSI)
Low-lying states in near-magic odd-odd nuclei and the effective interaction
Carlsson, B G
2014-01-01
The iterative quasi-particle-random-phase approximation (QRPA) method we previously developed to accurately calculate properties of individual nuclear states is extended so that it can be applied for nuclei with odd numbers of neutrons and protons. The approach is based on the proton-neutron-QRPA (pnQRPA) and uses an iterative non-hermitian Arnoldi diagonalization method where the QRPA matrix does not have to be explicitly calculated and stored. The method is used to calculate excitation energies of proton-neutron multiplets for several nuclei. The influence of a pairing interaction in the $T=0$ channel is studied.
Fermionic molecular dynamics for ground states and collisions of nuclei
International Nuclear Information System (INIS)
The antisymmetric many-body trial state which describes a system of interacting fermions is parametrized in terms of localized wave packets. The equations of motion are derived from the time-dependent quantum variational principle. The resulting Fermionic Molecular Dynamics (FMD) equations include a wide range of semi-quantal to classical physics extending from deformed Hartree-Fock theory to Newtonian molecular dynamics. Conservation laws are discussed in connection with the choice of the trial state. The model is applied to heavy-ion collisions with which its basic features are illustrated. The results show a great variety of phenomena including deeply inelastic collisions, fusion, incomplete fusion, fragmentation, neck emission, promptly emitted nucleons and evaporation. (orig.)
Final state interaction in semi-inclusive DIS off nuclei
Ciofi degli Atti, C
2003-01-01
The final state interaction in DIS of leptons off a nucleus A, due to the propagation of the struck nucleon debris and its hadronization in the nuclear environment is considered. The effective cross section of such a partonic system with the nucleons of the medium and its time dependence are estimated on the basis of a model which takes into account the production of hadrons due to the breaking of the color string and to gluon radiation. It is shown that the details of the propagation of the partonic system in the nuclear environment can be thoroughly investigated by the semi-inclusive process A(e,e'(A-1))X, in which the scattered lepton is detected in coincidence with the nucleus (A-1) in low energy and momentum states. The rescattering of the struck nucleon debris with the medium damps and distorts the momentum distributions of (A-1) in a way which is very sensitive to the details of effective cross section of the debris. The total cross section of the process on ^4He, ^16O, and ^40Ca, related to the probab...
Potentials for calculating both parity states in p-shell nuclei
International Nuclear Information System (INIS)
A Hamiltonian employing a ''physical'' central two-body potential has been used for simultaneous calculation of both normal and non-normal parity states of p-shell nuclei. Normal parity states have been calculated in a full 0/h bar/ω space and non-normal parity states in a full 1/h bar/ω space with the effects of spurious center-of-mass states completely removed. No explicit core is used in any of the shell model calculations. Results are compared with experimental data and previous shell model calculations for the following nuclei: 4He, /sup 5,6,7,8/Li, 8Be, /sup 13,14/C, and 13N. 34 refs., 9 figs., 3 tabs
Theoretical investigations of isoscalar, isovector and mixed symmetry states in skin nuclei
Tsoneva, N
2009-01-01
We present recent investigations on dipole and quadrupole excitations in spherical skin nuclei, particular exploring their connection to the thickness of the neutron skin. Our theoretical method relies on density functional theory, which provides us with a proper link between nuclear many-body theory of the nuclear ground state and its phenomenological description. For the calculation of the nuclear excited states we apply QPM theory. A new quadrupole mode related to pygmy quadrupole resonance (PQR) in tin isotopes is suggested.
Spectroscopy of high-lying states in actinide nuclei
Energy Technology Data Exchange (ETDEWEB)
Ahmad, I.; Back, B.B.; Betts, R.R. [and others
1995-08-01
In the course of studying positron-electron production during the collisions of uranium beams and tantalum targets, a careful measurement of the emitted gamma radiation was made using large Ge detectors. Many new high energy gamma rays were found, associated both with U-like and Ta-like fragments. To determine the origin of these gamma rays, a dedicated set of improved gamma-ray studies were carried out. The studies used four large (> 55%) Ge detectors mounted in the APEX chamber. States in {sup 238}U and {sup 232}Th were Coulomb excited using a {sup 208}Pb beam of 5.8 MeV/u. Heavy ions were detected in the large-area APEX multiwire proportional counters. The extensive beam monitoring of the APEX setup allowed precise normalization and accurate cross-section determinations. The Doppler shifts from upstream and downstream detectors permitted a precise confirmation of the incident beam energy to less than 0.05 MeV/A. A spectrum of gamma rays, corrected assuming emission from {sup 238}U.
Proton Single-Particle States In The Heaviest Actinide Nuclei
International Nuclear Information System (INIS)
The level structure of 249Bk has been investigated by measuring the γ-ray spectra following the α decay of a chemically and isotopically pure 253Es sample. Alpha-gamma coincidence measurement was performed using a Si detector for α particles and a 25% Ge detector for γ rays. A gamma-gamma coincidence measurement was performed with the Gammasphere spectrometer. The Es sample was obtained by extracting the 253Es which grew in a 253Cf source material produced in the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory. Additional information on the 249Bk levels was obtained from the study of γ rays produced in the β- decay of 249Cm. The 249Cm sample was produced by neutron irradiation of 248Cm. Using the results of the present study and the results of previous 248Cm(α,t) and 248Cm(3He,d) reaction spectra, the following single-particle states have been identified in 249Bk: 7/2+[633], 0.0 keV; 3/2-[521], 8.78 keV; 1/2+[400], 377.55 keV: 5/2+[642], 389.17 keV; 1/2-[530], 569.19 keV; 1/2-[521], 643.0 keV; 5/2-[523], 672.8 keV; 9/2+[624], 1075.1 keV. Four vibrational bands were identified at 767.9, 932.2, 1150.7 and 1223.0 keV with tentative assignments of {7/2+[633]x1-}9/2-, {7/2+[633]x0-}7/2-, {7/2+[633]x1-}5/2- and {7/2+[633]x0+}7/2+, respectively
He, Yugui; Feng, Jiwen; Huang, Chongyang; Chen, Fang; Liu, Maili; Liu, Chaoyang
2015-01-01
Dynamic nuclear polarization (DNP) has become a very important hyperpolarization method because it can dramatically increase the sensitivity of nuclear magnetic resonance (NMR) of various molecules. Liquid-state DNP based on Overhauser effect is capable of directly enhancing polarizations of all kinds of nuclei in the system. The combination of simultaneous Overhauser multi-nuclei enhancements with the multi-nuclei parallel acquisitions provides a variety of important applications in both MR spectroscopy (MRS) and image (MRI). Here we present two simple illustrative examples for simultaneously enhanced multi-nuclear spectra and images to demonstrate the principle and superiority. We have observed very large simultaneous DNP enhancements for different nuclei, such as 1H and 23Na, 1H and 31P, 19F and 31P, especially for the first time to report sodium ion enhancement in liquid. We have also obtained the simultaneous imaging of 19H and 31P at low field by solution-state DNP for the first time. This method can ob...
The emergence of deformation and rotational states in the many-nucleon quantum theory of nuclei
Rowe, D. J.
2016-02-01
The many-nucleon quantum mechanics of a nucleus is infinite-dimensional and, although simply defined, it has the potential for unlimited complexity. Nevertheless, the low-energy states of heavy open-shell nuclei exhibit properties that are remarkably well described by simple collective models. This paper examines this emergent simplicity from a perspective that closely parallels the emergence of shell structure in the Mayer-Jensen model. The result is an expression of the many-nucleon Hilbert space of a nucleus as an energy-ordered sum of subspaces each of which carries a microscopic version of the Bohr-Mottelson unified model. Each of the subspaces is characterized by nuclear states with a common intrinsic shape defined by its quadrupole moments. An emergence of simplicity and shape-coexistence in nuclei is then explained if it can be demonstrated that there is a relatively small and coherent mixing of the states of different collective subspaces.
Skyrme random-phase-approximation description of lowest Kπ=2γ+ states in axially deformed nuclei
Nesterenko, V. O.; Kartavenko, V. G.; Kleinig, W.; Kvasil, J.; Repko, A.; Jolos, R. V.; Reinhard, P.-G.
2016-03-01
The lowest quadrupole γ -vibrational Kπ=2+ states in axially deformed rare-earth (Nd, Sm, Gd, Dy, Er, Yb, Hf, W) and actinide (U) nuclei are systematically investigated within the separable random-phase-approximation (SRPA) based on the Skyrme functional. The energies Eγ and reduced transition probabilities B (E 2 ) of 2γ+ states are calculated with the Skyrme forces SV-bas and SkM*. The energies of two-quasiparticle configurations forming the SRPA basis are corrected by using the pairing blocking effect. This results in a systematic downshift of Eγ by 0.3-0.5 MeV and thus in a better agreement with the experiment, especially in Sm, Gd, Dy, Hf, and W regions. For other isotopic chains, a noticeable overestimation of Eγ and too weak collectivity of 2γ+ states still persist. It is shown that domains of nuclei with low and high 2γ+ collectivity are related to the structure of the lowest two-quasiparticle states and conservation of the Nilsson selection rules. The description of 2γ+ states with SV-bas and SkM* is similar in light rare-earth nuclei but deviates in heavier nuclei. However SV-bas much better reproduces the quadrupole deformation and energy of the isoscalar giant quadrupole resonance. The accuracy of SRPA is justified by comparison with exact RPA. The calculations suggest that a further development of the self-consistent calculation schemes is needed for a systematic satisfactory description of the 2γ+ states.
Scaling of the giant dipole resonance widths in hot rotating nuclei from the ground state values
Banerjee, S R; Pandit, Deepak; Mukhopadhyay, S; Pal, Surajit
2008-01-01
The systematics of the giant dipole resonance (GDR) widths in hot and rotating nuclei are studied in terms of temperature T, angular momentum J and mass A. The ambiguity in describing the experimental data in the temperature range of 1 - 2 MeV in terms of the thermal shape fluctuation model (TSFM) in the liquid drop formalism has been resolved using a modified approach to estimate the average values of T, J and A in the decay of the compound nucleus. The values of the ground state GDR widths have been extracted from the TSFM parametrization in the liquid drop limit for the corrected T, J and A for a given system and compared with the corresponding available systematics of the experimentally measured ground state GDR widths for a range of nuclei from A = 45 to 194. Amazingly, the nature of the theoretically extracted ground state GDR widths matches remarkably well, though 1.5 times smaller, with the experimentally measured ground state GDR widths consistently over a wide range of nuclei.
Macroscopic-microscopic calculations of ground state properties of superheavy nuclei
Institute of Scientific and Technical Information of China (English)
ZHI Qi-jun; Mao Ying-chen; REN Zhong-zhou
2006-01-01
We systematically calculate the ground state properties of superheavy even-even nuclei with proton number Z=94-118.The calculations are based on the liquid drop macroscopic model and the microscopic model with the modified single-particle oscillator potential. The calculated binding energies and α-decay energies agree well with the experimental data.The reliability of the macroscopic-microscopic(MM)model for superheavy nuclei is confirmed by the good agreement between calculated results and experimental ones. Detailed comparisons between our calculations and M(o)ller's are made.It is found that the calculated results also agree with M(o)ller's results and that the MM model is insensitive to the microscopic single-particle potential. Calculated results are also compared with results from relativistic mean-field (RMF)model and from Skyrme-Hatree-Fock(SHF) model.In addition,half-lives,deformations and shape coexistence are also investigated.The properties of some unknown nuclei are predicted and they will be useful for future experimental researches of superheavy nuclei.
Excited State Lifetime Measurements in Rare Earth Nuclei with Fast Electronics
Werner, V.; Cooper, N.; Bonett-Matiz, M.; Williams, E.; Régis, J.-M.; Rudigier, M.; Ahn, T.; Anagnostatou, V.; Berant, Z.; Bunce, M.; Elvers, M.; Heinz, A.; Ilie, G.; Jolie, J.; Radeck, D.; Savran, D.; Smith, M.
2011-09-01
We investigated the collectivity of the lowest excited 2+ states of even-even rare earth nuclei. The B(E2) excitation strengths of these nuclei should directly correlate to the size of the valence space, and maximize at mid-shell. The previously identified saturation of B(E2) strength in well-deformed rotors at mid-shell is put to a high precision test in this series of measurements. Lifetimes of the 2+1 states in 168Hf and 174W have been measured using the newly developed LaBr3 scintillation detectors. The excellent energy resolution in conjunction with superb time properties of the new material allows for reliable handling of background, which is a source of systematic error in such experiments. Preliminary lifetime values are obtained and discussed in the context of previous and ongoing work.
Study of ground and excited state decays in N ≈ Z Ag nuclei
Directory of Open Access Journals (Sweden)
Moschner K.
2015-01-01
Full Text Available A decay spectroscopy experiment was performed within the EURICA campaign at RIKEN in 2012. It aimed at the isomer and particle spectroscopy of excited states and ground states in the mass region below the doubly magic 100Sn. The N = Z nuclei 98In, 96Cd and 94Ag were of particular interest for the present study. Preliminary results on the neutron deficient nuclei 93Ag and 94Ag are presented. In 94Ag a more precise value for the half-life of the ground state’s superallowed Fermi transition was deduced. In addition the energy spectra of the mentioned decay could be reproduced through precise Geant4 simulations of the used active stopper SIMBA. This will enable us to extract Qβ values from the measured data. The decay of 93Ag is discussed based on the observed implantation-decay correlation events.
Systematics of ground state multiplets of atomic nuclei in the delta-interaction approach
Energy Technology Data Exchange (ETDEWEB)
Imasheva, L. T.; Ishkhanov, B. S.; Stepanov, M. E., E-mail: stepanov@depni.sinp.msu.ru [Moscow State University, Faculty of Physics (Russian Federation); Tretyakova, T. Yu. [Moscow State University, Skobeltsyn Institute of Nuclear Physics (Russian Federation)
2015-12-15
Pairing forces between nucleons in an atomic nucleus strongly influence its structure. One of the manifestations of pair interaction is the ground state multiplet (GSM) formation in the spectrum of low-lying excited states of even–even nuclei. The value of GSM splitting is determined by the value of pair interaction of nucleons; for each isotope, it can be estimated on the basis of experimental nuclear masses. The quality of this estimate is characterized by the degree of reproduction of GSM levels in the nucleus. The GSM systematics in even–even nuclei with a pair of identical nucleons in addition to the filled nuclear core is considered on the basis of delta interaction.
Properties of the lowest negative parity states in N= 82 magic nuclei
International Nuclear Information System (INIS)
Octupole features in rare earth nuclei observed that, in the region beyond the doubly closed shell structure in 132Sn, the d5/2 and the h11/2 proton orbitals are quite close together and are also near the Fermi surface. In the present paper, the octupole features has been examined in the low lying 3 states in the N=82 isotonic sequence beginning with the doubly closed shell nucleus 132Sn
Effective Field Theory for Halo Nuclei: Shallow p-Wave States
Bertulani, C.A.; Hammer, H. -W.; van Kolck, U.
2002-01-01
Halo nuclei are a promising new arena for studies based on effective field theory (EFT). We develop an EFT for shallow p-wave states and discuss the application to elastic n-alpha scattering. In contrast to the s-wave case, both the scattering length and effective range enter at leading order. We also discuss the prospects of using EFT in the description of other halos, such as the three-body halo nucleus 6He.
High-Spin States in and Around Doubly-Magic Nuclei
International Nuclear Information System (INIS)
The study of high-spin states in regions of doubly-magic nuclei performed with the use of deep-inelastic heavy ion reactions is reviewed. New and tentative results concerning high-spin states in the 48Ca and yrast structures in 47Ca, 47K, 49Ca and 49Sc isotopes are presented. The status of the high-spin state study in the region of 132Sn and 208Pb is outlined including discussion of recently obtained results in the 208Pb core and the 206Hg two-proton-hole nucleus. (author)
High-spin states in and around doubly-magic nuclei
Broda, R.
2001-01-01
The study of high-spin states in regions of doubly-magic nuclei performed with the use of deep-inelastic heavy ion reactions is reviewed. New and tentative results concerning high-spin states in the 48Ca and yrast structures in 47Ca, 47K, 49Ca and 49Sc isotopes are presented. The status of the high-spin state study in the region of 132Sn and 208Pb is outlined, including discussion of recently obtained results in the 208Pb core and the 206Hg two-proton-hole nucleus.
Collective nature of $0^{+}$-states in deformed rare-earth nuclei
Garistov, V P
2000-01-01
The description of the energiy spectra of $0^{+}$ states for rare-earth nuclei has been done involving the degree of the collectivity of corresponding $0^{+}$-state as a systematics parameter. Holshtein-Primakoff representation leads to very good agreement with experiment. Within the framework of this approach the parameter of the collectivity is mainly determined by pairs of particles constructed on single ''effective'' level. The results may be helpful both for nuclear structure experimentalists and theorists in their investigations of low-lying states structure and transition probabilities.
Lupulescu, Adonis; Frydman, Lucio
2011-10-01
Recent years have witnessed efforts geared at increasing the sensitivity of NMR experiments, by relying on the suitable tailoring and exploitation of relaxation phenomena. These efforts have included the use of paramagnetic agents, enhanced (1)H-(1)H incoherent and coherent transfers processes in 2D liquid state spectroscopy, and homonuclear (13)C-(13)C spin diffusion effects in labeled solids. The present study examines some of the opportunities that could open when exploiting spontaneous (1)H-(1)H spin-diffusion processes, to enhance relaxation and to improve the sensitivity of dilute nuclei in solid state NMR measurements. It is shown that polarization transfer experiments executed under sufficiently fast magic-angle-spinning conditions, enable a selective polarization of the dilute low-γ spins by their immediate neighboring protons. Repolarization of the latter can then occur during the time involved in monitoring the signal emitted by the low-γ nuclei. The basic features involved in the resulting approach, and its potential to improve the effective sensitivity of solid state NMR measurements on dilute nuclei, are analyzed. Experimental tests witness the advantages that could reside from utilizing this kind of approach over conventional cross-polarization processes. These measurements also highlight a number of limitations that will have to be overcome for transforming selective polarization transfers of this kind into analytical methods of choice.
Halo Structure of Isobaric Analogue States in A= 21 and 17 Mirror Nuclei
Institute of Scientific and Technical Information of China (English)
周书华; 周静
2002-01-01
The root-mean-square (rms) radii of the last nucleons in the 2s1/2 states of 21 Ne, 21 Na, 17 O and 17 F are found to be 4.4±0.5, 5.2±0.6, 4.3±0.5 and 5.0±0. 6 fm, respectively, from transfer reaction data. The results show that the 2s1/2 states of 21 Na and 17F are proton halo states, while the analogous states in their mirror nuclei 21 Ne and 17O can be considered as neutron skin states. Comparisons among the rms radii of these states lead us to expect that a neutron halo nucleus has a proton halo mirror partner, and the Coulomb barrier is a determinant factor limiting the extension of the rms radius of the loosely bound proton.
Halo Structure of the Isobaric Analog States in Some Mirror Nuclei
Institute of Scientific and Technical Information of China (English)
2001-01-01
Using ANC method the rms radius of the last nucleon in the 2s1/2 isobaric analog states of 21Ne/2lNa and 17O / 17F is extracted from transfer reaction data. The results are summarized in Tab. 1. The 2s1/2 single proton states in 21Na and 17O have the rms radii almost twice as large as that for their core nuclei (2.88 fin for 20Ne and 2.71 fm for 16O) and are proton halo states, while their isobaric analog states in 2INe and I7O can be considered as neutron skin states, because the neutrons in these states have one third of the probability staying out of the nuclear interaction range. The obvious difference in the rms radii between a mirror pair indicates the binding energy difference between the
High-spin states in the transitional odd-odd nuclei 150Eu and 152Tb
International Nuclear Information System (INIS)
The (7Li, 5n) and (11B, 5n) reactions have been used to study the high-spin states in the two odd-odd nuclei 150Eu and 152Tb. Three decoupled bands have been evidenced in each nucleus belonging to the same configurations [f 7/2]sub(n) [h 11/2]sub(p), [h 9/2]sub(n) [h 11/2 ]sub(p) and [i 13/2]sub(n) [h 11/2]sub(p). The latter one is well developped and improves our knowledge of this system between the spherical and deformed region. The analysis of the collective moment of inertia and transition ratios strongly suggests an increase of the deformation when the rotational frequency increases in these two transitional nuclei 150Eu and 152Tb
High-spin states in boson models with applications to actinide nuclei
Kuyucak, S
1995-01-01
We use the 1/N expansion formalism in a systematic study of high-spin states in the sd and sdg boson models with emphasis on spin dependence of moment of inertia and E2 transitions. The results are applied to the high-spin states in the actinide nuclei ^{232}Th, ^{234-238}U, where the need for g bosons is especially acute but until now, no realistic calculation existed. We find that the d-boson energy plays a crucial role in description of the high-spin data.
International Nuclear Information System (INIS)
Influence of spin components of the effective nuclear forces on the structure of electric type eicited states is investigated. Both the central and spin components of the effective NN-forces are selected in a separable form with the same radial dependence. As is shown, there are no considerable changes in characteristics of the lowest excited states in spherical nuclei as well as in the integral properties of electric resonances (like the region of the localization, the total excitation probability, etc.). Changes in the structure and transition densities for a number of collective states in 208Pb with energies Esub(x)>10 MeV are noted. At an excitation energy Esub(x) approximately 20 MeV the collective states, which are formed by single-particle spin-flip transitions, appear. These states have a small reduced probability B(Elambda; 0+ → lambdasup(π)) but they are strongly excited in the inelastic electron stattering at backward angles
Furusawa, Shun; Yamada, Shoichi; Suzuki, Hideyuki
2013-01-01
We construct new equations of state for baryons at sub-nuclear densities for the use in core-collapse simulations of massive stars. The abundance of various nuclei is obtained together with thermodynamic quantities. A model free energy is constructed, based on the relativistic mean field theory for nucleons and the mass formula for nuclei with the proton number up to ~ 1000. The formulation is an extension of the previous model, in which we adopted the liquid drop model to all nuclei under the nuclear statistical equilibrium. We reformulate the new liquid drop model so that the temperature dependences of bulk energies could be taken into account. Furthermore, we extend the region in the nuclear chart, in which shell affects are included, by using theoretical mass data in addition to experimental ones. We also adopt a quantum theoretical mass evaluation of light nuclei, which incorporates the Pauli- and self-energy shifts that are not included in the ordinary liquid drop model. The pasta phases for heavy nucle...
Extended M1 sum rule for excited symmetric and mixed-symmetry states in nuclei
Smirnova, N A; Leviatan, A; Ginocchio, J N; Fransen, C
2002-01-01
A generalized M1 sum rule for orbital magnetic dipole strength from excited symmetric states to mixed-symmetry states is considered within the proton-neutron interacting boson model of even-even nuclei. Analytic expressions for the dominant terms in the B(M1) transition rates from the first and second $2^+$ states are derived in the U(5) and SO(6) dynamic symmetry limits of the model, and the applicability of a sum rule approach is examined at and in-between these limits. Lastly, the sum rule is applied to the new data on mixed-symmetry states of 94Mo and a quadrupole d-boson ratio $nd(0^+_1)/nd(2^+_2) \\approx 0.6$ is obtained in a largely parameter-independent way
Structure of high spin states of 76Kr and 78Kr nuclei
Indian Academy of Sciences (India)
U R Jakhar; H L Yadav; A Ansari
2005-12-01
Following a fully self-consistent cranked Hartree-Fock-Bogoliubov (CHFB) approach with a pairing+quadrupole+hexadecapole model interaction Hamiltonian the structure of the yrast states of 76,78Kr nuclei is studied up to angular momentum = 24. Evolution of the shape with spin, and rotation alignment of proton as well as neutron 0g9/2 orbitals is investigated along with the inter- and intra-nucleus variations of the factors as a function of . We find that the shape of 78Kr remains prolate all through up to = 24, whereas 76Kr becomes triaxial beyond = 12.
Role of T=0 pairing in Gamow-Teller states in N=Z nuclei
Bai, C L; Sasano, M; Uesaka, T; Hagino, K; Zhang, H Q; Zhang, X Z; Xu, F R
2012-01-01
Gamow-Teller (GT) states in N=Z nuclei with the mass number A from 48 to 64 are studied by using Hartree-Fock-Bogoliubov + quasi-particle random phase approximation (HFB+QRPA) with Skyrme interactions. The isoscalar spin-triplet (T=0,S=1) pairing interaction is taken into account in QRPA calculations. It is found in the context of SU(4) symmetry in the spin-isospin space that the GT strength of lower energy excitations is largely enhanced by the T=0 pairing interaction which works cooperatively with the T=1 pairing interaction in the ground state. A two-peaked structure observed recently in $(p,n)$ reaction on $^{56}$Ni can be considered as a manifestation of the role of T=0 pairing in the GT collective states.
Study of the giant dipole resonance built on highly excited states in Sn and Dy nuclei
International Nuclear Information System (INIS)
A study is presented of the giant dipole resonance built on highly excited states. The aim is to get more detailed information on the properties of the GDR and to use it as a tool for the investigation of nuclear structure at high excitation energy. The high energy γ-rays seen from the decay of excited state GDRs in heavy ion fusion reactions reflect the average properties of the states populated by the γ-emission. The measurements at different initial excitation energies of 114Sn provide information on the nuclear level density near the particle separation energy at an average angular momentum of 10ℎ. The study of shape changes at very high spin in 152-156Dy nuclei is presented. A theoretical model developed to describe fusion-evaporation reactions is presented. 149 refs.; 63 figs.; 13 tabs
Neutron Single-Particle States in r-Process Nuclei Near Closed Shells
Energy Technology Data Exchange (ETDEWEB)
Thomas, J.S. [Department of Physics and Astronomy, Rutgers University, New Brunswick, NJ 08903 (United States); Bardayan, D.W. [Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Blackmon, J.C. [Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Cizewski, J.A. [Department of Physics and Astronomy, Rutgers University, New Brunswick, NJ 08903 (United States); Fitzgerald, R.P. [Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 (United States); Greife, U. [Department of Physics, Colorado School of Mines, Golden, CO 80401 (United States); Gross, C.J. [Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Johnson, M.S. [Department of Physics and Astronomy, Rutgers University, New Brunswick, NJ 08903 (United States); Jones, K.L. [Department of Physics and Astronomy, Rutgers University, New Brunswick, NJ 08903 (United States); Kozub, R.L. [Physics Department, Tennessee Technological University, Cookeville, TN 38505 (United States); Liang, J.F. [Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Livesay, R.J. [Department of Physics, Colorado School of Mines, Golden, CO 80401 (United States); Ma, Z. [Physics Department, University of Tennessee, Knoxville, TN 37996 (United States); Moazen, B.H. [Physics Department, Tennessee Technological University, Cookeville, TN 38505 (United States); Nesaraja, C.D. [Physics Department, Tennessee Technological University, Cookeville, TN 38505 (United States); Shapira, D. [Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Smith, M.S. [Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Visser, D.W. [Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 (United States)
2005-07-25
We have begun a program to measure (d,p) reactions on neutron-rich nuclei, probing the single-particle states near the N=50 and N=82 closed shells. We have measured the neutron transfer on two N=50 isotones, {sup 82}Ge and {sup 84}Se, at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory. We have also performed a test measurement of transfer on {sup 124}Sn to develop the techniques to study the {sup 2}H({sup 130,132}Sn,p){sup 131,133}Sn reactions. Preliminary results for {sup 85}Se are consistent with 5/2{sup +} ground state and 1/2{sup +} first excited state assignments, and the successful measurement of the {sup 2}H({sup 124}Sn,p){sup 125}Sn reaction demonstrates the feasibility to measure the (d,p) reaction with neutron-rich {sup 130,132}Sn beams.
International Nuclear Information System (INIS)
Coulomb excitation is a very precise tool to measure excitation probabilities and provide insight on the collectivity of nuclear excitations and in particular on nuclear shapes. In the last few years radioactive ion beam facilities such as HRIBF opened unique opportunities to explore the structure of nuclei in the regions near the doubly magic nuclei 78Ni (Z=28 and N=50) and 132Sn (Z=50 and N=82). For this purpose we have developed specialized methods and instrumentation to measure various observables. There is also the opportunity to perform precision experiments with stable beams using exactly the same state-of-the-art instrumentation and techniques as with their radioactive ion beam counterpart. I describe some of the recent efforts at HRIBF to do more precise measurements using particle-gamma techniques.
Interplay of collective and single-particle states in neutron deficient transitional nuclei
International Nuclear Information System (INIS)
This thesis reports several in-beam γ-ray spectroscopic studies of rotational states in neutron deficient nuclei in the transitional A = 120 and A = 170 mass regions following heavy-ion reactions. The experiments were performed using high-resolution multidetector arrays at Daresbury Laboratory, England and the Tandem Accelerator Laboratory, Niels Bohr Institute, Denmark. The Daresbury Recoil Separator and a 4π charged particle Si-detector system in conjunction with 11 neutron detectors were used in order to identify some of the very neutron deficient and previously unknown residual nuclei that were produced in the reactions. The experimental results are compared to theoretical mean field calculations which minimize the total energy of the nucleus as a function of rotational frequency and deformation, for various configurations. Within the limitations of these so called Total Routhian Surface (TRS) calculations it is possible to draw conclusions of the underlying microscopic mechanisms behind the experimentally observed properties of rotational band structures. The emphasis is put on studies of the shape polarizing properties of different single-particle orbits, especially on the role of deformed intruder states. (39 refs.) (au)
Fermionic structure of collective states of light nuclei and the Dyson boson mapping
International Nuclear Information System (INIS)
Full text: The main objective of studying microscopic nature of collective states is to derive the parameters of the model of interacting bosons based on nucleon degrees of freedom. To achieve this the paper represents [1, 2], first of all, cutoff of huge Hilbert shell space to so-called SD - pair subspace, constructed from the S-and D-nucleon pairs. For this purpose, we used the Dyson-type boson mapping of fermion operators of the studied system. We prove the validity of cutting off huge fermionic space, since it is considered in the model of interacting bosons that low-energy states of nuclei are determined by the properties of nucleons located in such cut off SD - pair space. So we can divide the Dyson boson Hamiltonian into the collective and non-collective parts. This Hamiltonian includes another term reflecting the relationship between collective and non-collective freedom degrees of the system. Diagonalization of such Hamiltonian and comparison of the obtained numerical values with the numerical results of exact shell-model calculations for the same nuclei in the sd- and pf - shell region shows that our method gives a good approximation to description of nuclei properties. It is shown that the role of coupling effect between collective and non-collective freedom degrees in the formation of spectrum and B(E2) values is essential. It should be noted that after mapping of the shell space as the ideal boson one, only three - s, d, g - the bosons corresponding to collective Tamm-Dancoff-skiy phonon modes with l=0, 2, 4, respectively, are left as collective bosons. The boson Hamiltonian is diagonalized in this model pair space. The method effectively reproduces not only excitation energies, but also the values of B(E2) and quadrupole moments obtained during exact shell-model calculations. The theory is applied to light nuclei 40,42Ca, 44Ti. The numerical results represent the experimental data quite satisfactorily. (author) Reference: 1. K. Takada, et al
Correlation of β-band with ground state band in medium mass nuclei
International Nuclear Information System (INIS)
The low energy levels of even Z even N nuclei in medium mass region A = 150-200 away from closed shells develop collective characteristics. The lowest levels can be grouped into three K-bands. The lowest one based on the ground state forms the ground state rotational band. The rotational band, based on the axially symmetric vibration of the nuclear core with K= 02 is called the beta vibrational band. The one based on the axially asymmetric vibration of the nuclear core with K=2 projection on the symmetry axis is called the K=2, γ-vibrational band. There is interest in the nature of the K= 02 band. This is called the geometric view of the Bohr Mottelson unified collective model
Contribution of excited states to stellar weak-interaction rates in odd-A nuclei
Sarriguren, Pedro
2016-01-01
Weak-interaction rates, including beta-decay and electron capture, are studied in several odd-A nuclei in the pf-shell region at various densities and temperatures of astrophysical interest. Special attention is paid to the relative contribution to these rates of thermally populated excited states in the decaying nucleus. The nuclear structure involved in the weak processes is studied within a quasiparticle random-phase approximation with residual interactions in both particle-hole and particle-particle channels on top of a deformed Skyrme Hartree-Fock mean field with pairing correlations. In the range of densities and temperatures considered, it is found that the total rates do not differ much from the rates of the ground state fully populated. In any case, the changes are not larger than the uncertainties due to the nuclear model dependence of the rates.
Halo structure of isobaric analogue states in A = 21 and 17 mirror nuclei
Zhou Shu Hua
2002-01-01
The root-mean-square (rms) radii of the last nucleons in the 2s sub 1 sub / sub 2 states of sup 2 sup 1 Ne, sup 2 sup 1 Na, sup 1 sup 7 O and sup 1 sup 7 F are found to be 4.4 +- 0.5, 5.2 +- 0.6, 4.3 +- 0.5 and 5.0 +- 0.6 fm, respectively, from transfer reaction data. The results show that the 2s sub 1 sub / sub 2 states of sup 2 sup 1 Na and sup 1 sup 7 F are proton halo states, while the analogous states in their mirror nuclei sup 2 sup 1 Ne and sup 1 sup 7 O can be considered as neutron skin states. Comparisons among the rms radii of these states lead authors to expect that a neutron halo nucleus has a proton halo mirror partner, and the Coulomb barrier is a determinant factor limiting the extension of the rms radius of the loosely bound proton
Alpha cluster states in light nuclei populated through the (6Li,d) reaction
Energy Technology Data Exchange (ETDEWEB)
Borello-Lewin, Thereza; Rodrigues, M.R.D.; Horodynski-Matsushigue, L.B.; Duarte, J.L.M.; Rodrigues, C.L.; Souza, M.A. [Universidade de Sao Paulo (IF/USP), SP (Brazil). Inst. de Fisica; Cunsolo, A.; Cappuzzello, F. [Universita di Catania (Italy). Istituto Nazionale di Fisica Nucleare. Lab. Nazionali del Sud; Ukita, Gilberto Mitsuo [Universidade de Santo Amaro (UNISA), Sao Paulo, SP (Brazil). Fac. de Psicologia
2011-07-01
Full text: The alpha cluster correlation is an important concept in the nuclear physics of light nuclei. The main purpose of the research program in progress is the investigation of the alpha clustering phenomenon in (x{alpha}) and(x{alpha}+{nu}) nuclei through the ({sup 6}Li,d) alpha transfer reaction. In fact, there is scarce experimental information on the subject, in particular associated with resonant states predicted near (x{alpha}) and (x{alpha}+{nu}) thresholds. Measurements of the {sup 12},{sup 13}C({sup 6}Li,d) {sup 16},{sup 17}O reactions, at an incident energy of 25.5 MeV, have been performed employing the Sao Paulo Pelletron-Enge Split-Pole facility and the nuclear emulsion detection technique. The work is under way and an experimental energy resolution of 30 keV was obtained. Near the (4{alpha}) breakup threshold in {sup 16}O, three narrow alpha resonances, not previously measured, were detected, revealing important {alpha} + {sup 12}C(G.S.) components. One of these resonances corresponds to the known 0{sup +} state at 15.1 MeV[5] of excitation that has probably, according to Funaki et al., the gas like configuration of the 4{alpha} condensate state, with a very dilute density and a large component of {alpha} + {sup 12}C(Hoyle) configuration. As was already mentioned, our experimental information points to the necessity of including the {alpha} + {sup 12}C(G.S.) component in the wave function. (author)
International Nuclear Information System (INIS)
For the test of nuclear models the study of the properties of nuclear states of high angular momentum is especially important, because such states can often be given very simple theoretical descriptions. High spin states are easily populated by use of reactions initiated by alpha particles or heavy ions. In this thesis a number of low-medium mass nuclei have been studied, with emphasis on high spin states. (Auth.)
Ground-State Properties of Z = 59 Nuclei in the Relativistic Mean-Field Theory
Institute of Scientific and Technical Information of China (English)
ZHOU Yong; MA Zhong-Yu; CHEN Bao-Qiu; LI Jun-Qing
2000-01-01
Ground-state properties of Pr isotopes are studied in a framework of the relativistic mean-field (RMF) theory using the recently proposed parameter set TM1. Bardeen-Cooper-Schrieffer (BCS) pproximation and blocking method is adopted to deal with pairing interaction and the odd nucleon, respectively. The pairing forces are taken to be isospin dependent. The domain of the validity of the BCS theory and the positions of neutron and proton drip lines are studied. It is shown that RMF theory has provided a good description of the binding energy,isotope shifts and deformation of nuclei over a large range of Pr isotopes, which are in good agreement with those obtained in the finite-range droplet model.
Study of particle unbound states in 25Mg and 25Al nuclei by the reaction 24Mg(d,pn)
International Nuclear Information System (INIS)
Stripping reactions to unbound states in 25Mg and 25Al nuclei were investigated by measuring proton-neutron angular correlation. An analysis of triple differential cross sections has been given. New high excited unbound states in the energy range from 8.1 to 11.6 MeV for 25Mg and from 4.6 to 8.3 MeV for 25Al nuclei were observed. Angular distributions of double differential cross sections were found for most of the levels. (author)
Deep-hole and high-lying particle states in heavy nuclei
International Nuclear Information System (INIS)
Our present knowledge on single-particle strength functions from one nucleon transfer reactions is reviewed. Results on deeply-bound neutron hole states in the Sn and Pb region are discussed with emphasis on the investigation of a very large excitation energy range. The first measurements on the γ-decay of deeply-bound hole states in the Sn isotopes are reported. High energy neutron and proton stripping reactions are used to study the particle response function. These reactions are particularly well suited to the study of high-spin outer subshells. For the proton states, the behaviour of the 1h11/2 and 1i13/2 strength distributions, as a function of deformation in the Sm region, is discussed. Strong transitions to high-lying neutron states are observed in the 112,116,118,120,122,124Sn and 208Pb nuclei. The empirical systematics for both proton and neutron particle strength distributions are compared to the predictions from the quasi particle-phonon and the single-particle vibration coupling nuclear models. (orig.)
High-Resolution NMR of Quadrupolar Nuclei in the Solid State
Energy Technology Data Exchange (ETDEWEB)
Gann, Sheryl Lee
1995-11-30
This dissertation describes recent developments in solid state nuclear magnetic resonance (NMR), for the most part involving the use of dynamic-angle spinning (DAS) NMR to study quadrupolar nuclei. Chapter 1 introduces some of the basic concepts and theory that will be referred to in later chapters, such as the density operator, product operators, rotations, coherence transfer pathways, phase cycling, and the various nuclear spin interactions, including the quadrupolar interaction. Chapter 2 describes the theory behind motional averaging experiments, including DAS, which is a technique where a sample is spun sequentially about two axis oriented at different angles with respect to the external magnetic field such that the chemical shift and quadrupolar anisotropy are averaged to zero. Work done on various rubidium-87 salts is presented as a demonstration of DAS. Chapter 3 explains how to remove sidebands from DAS and magic-angle spinning (MAS) experiments, which result from the time-dependence of the Hamiltonian under sample spinning conditions, using rotor-synchronized {pi}-pulses. Data from these experiments, known as DAH-180 and MAH-180, respectively, are presented for both rubidium and lead salts. In addition, the applicability of this technique to double rotation (DOR) experiments is discussed. Chapter 4 concerns the addition of cross-polarization to DAS (CPDAS). The theory behind spin locking and cross polarizing quadrupolar nuclei is explained and a method of avoiding the resulting problems by performing cross polarization at 0{sup o} (parallel) with respect to the magnetic field is presented. Experimental results are shown for a sodium-23 compound, sodium pyruvate, and for oxygen-17 labeled L-akmine. In Chapter 5, a method for broadening the Hartmann-Hahn matching condition under MAS, called variable effective field cross-polarization (VEFCI?), is presented, along with experimental work on adamantane and polycarbonate.
Phonon-state mixing in the lowest two $I^{\\pi}=2^+$ states of anharmonic vibration nuclei
Qin, Z Z
2016-01-01
The phonon-configuration mixing in $2^+_1$ and $2^+_2$ states beyond the anharmonic-vibration collectivity explains the universal correlations of $Q(2^+_1)=-Q(2^+_2)$. It also suggests another strong magnetic-moment correlation of $\\mu(2^+_1)=\\mu(2^+_2)$ for the anharmonic-vibration nuclei, which is further confirmed by our experimental-data survey. The global relation between $|Q(2^+)|$, $E_{2^+_1}$ and $E_{2^+_2}$ is analytically established according to the phonon-configuration mixing scheme, and roughly agrees with experiments. This relation may provide a convenient estimation of $|Q(2^+)|$ only with spectral input. The $N_pN_n$ scheme suggests that the phonon-configuration mixing may be driven by the neutron-proton interaction.
International Nuclear Information System (INIS)
We present a new approach for the measurement of resonance excitation functions of neutron-rich nuclei using Doppler shift information. Preliminary data from the first application of the method is presented in the spectroscopy studies of 7He isobaric analog states in 7Li. (orig.)
Rong-Yao, Yang; Si-Na, Wei; Dong-Rui, Zhang
2016-01-01
The sensitive correlations between the low-density halo structure and the high-density properties of the nuclear equation of state (EOS) are constructed in light kaonic nuclei with the relativistic mean-field theory. More specifically, the $1p_{1/2}$ halo spreads out linearly with increasing the pressure and sound velocity square at supra-normal densities and quadratically with decreasing the incompressibility at saturation density. These results suggest that the novel halo in light kaonic nuclei can serve as a sensitive indicator of the nuclear EOS of symmetric matter at supra-normal densities.
Fujita, Y; Fujita, H; Adachi, T; Berg, GPA; Caurier, E; Fujimura, H; Hara, K; Hatanaka, K; Janas, Z; Kamiya, J; Kawabata, T; Langanke, K; Martinez-Pinedo, G; Noro, T; Roeckl, E; Shimbara, Y; Shinada, T; van der Werf, SY; Yoshifuku, M; Yosoi, M; Zegers, RGT
2002-01-01
Under the assumption that isospin is a good quantum number, symmetry is expected for the transitions from the ground states of T = 1, T-z = +/-1 nuclei to the common excited states of the T-z = 0 nucleus situated between the two nuclei. The symmetry can be studied by comparing the strengths of Gamow
Collective excited states in even–even nuclei with quadrupole and octupole deformations
International Nuclear Information System (INIS)
Deformed even–even nuclei with quadrupole and octupole deformations are investigated on the basis of a nonadiabatical collective model. It is shown that the model satisfactorily describes energy levels of the yrast and first nonyrast bands with alternating parity in the rare-earth nuclei 150Nd, 152,154Sm, 154Gd, 156Dy, 162,164Er and the actinides 232,234,236,238U. In the nuclei 156,158Gd, 224Ra, 228Th and 240Pu the energy levels of second nonyrast bands are also described. The structure of the considered alternating-parity bands is examined in terms of odd–even staggering diagrams. (author)
Study of superdeformed state of nuclei in $Z=70-80$ drip-line region
Mahapatro, S; Kumar, Bharat; Patra, S K
2015-01-01
We study binding energy, root- mean square radius, quadrapole deformation parameter, two-neutron separation energy and single particle energy levels for various isotopes of Ytterbium (Yb), Hafnium(Hf), Tungsten(W), Osmium(Os), Platinum(Pt) and Mercury(Hg) in $Z = 70 - 80$ drip-line region starting from $N =80$ to $N=170$ within the formalism of relativistic mean field (RMF) theory. We compared our results with Finite Range Droplet Model(FRDM) and experimental data and found that the calculated results are in good agreement. The nuclei $^{168}$Yb,$^{172}$Hf, $^{176}$W, $^{184}$Os, $^{188}$Pt, $^{196}$Hg are found to be most stable isotope in the respective series in the neutron-deficient region. We also observe that there is a shape transition at about $A=190$ in $Z=70-80$ region. The shape changes from oblate to highly prolate shape in their intrinsic ground state. We have also studied probable decay mechanisms of these elements.
Evolution of ground state nuclear shapes in tungsten nuclei in terms of interacting boson model
Khalaf, A. M.; El-Shal, A. O.; Taha, M. M.; El-Sayed, M. A.
2016-03-01
The tungsten nuclei 180-190W are investigated within the framework of the interacting boson model using an intrinsic coherent state formalism. The Hamiltonian operator contains only multipole operators of the subalgebra associated with the dynamical symmetries SU(3) and O(6). The study includes the behavior of potential energy surfaces (BES's) and critical points in the space of the model parameters to declare the geometric character of the tungsten isotopic chain. Some selected energy levels and reduced E2 transition probabilities B(E2) for each nucleus are calculated to adjust the model parameters by using a computer code PH INT and simulated computer fitting programme to fit the experimental data with the IBM calculation by minimizing the root mean square deviations. The 180-190W isotopes lies in shape transition SU(3)-O(6) region of the IBM such that the lighter isotopes comes very clare to the SU(3) limit, while the behavior ones tend to be near the γ-unstable O(6) limit.
Rotating nuclei: from ground state to the extremes of spin and deformation
Afanasjev, A V
2015-01-01
The rotating nuclei represent one of most interesting subjects for theoretical and experimental studies. They open a new dimension of nuclear landscape, namely, spin direction. Contrary to the majority of nuclear systems, their properties sensitively depend on time-odd mean fields and currents in density functional theories. Moreover, they show a considerable interplay of collective and single-particle degrees of freedom. In this chapter, I discuss the basic features of the description of rotating nuclei in one-dimensional cranking approximation of covariant density functional theory. The successes of this approach to the description of rotating nuclei at low spin in pairing regime and at high spin in unpaired regime in wide range of deformations (from normal to hyperdeformation) are illustrated. I also discuss the recent progress and open questions in our understanding of the role of proton-neutron pairing in rotating nuclei at $N\\approx Z$, the physics of band termination and other phenomena in rotating nuc...
On the direct nucleon decay of high-spin subbarrier single-particle states in near-magic nuclei
Chekomazov, G. A.; Urin, M. H.
1996-01-01
The description of the direct nucleon decay of high-spin subbarrier one-particle states in near-magic nuclei is attempted using a simple optical model and the simplest version of the coupled-channel approach. The branching ratios for the direct decay of the several single-neutron states in $^{209}Pb$ and $^{91}Zr$ to the ground state and to the low-lying collective states of $^{208}Pb$ and $^{90}Zr$, respectively, are evaluated. Results are compared with recent experimental data.
Snow crystals and the identification of the nuclei in the northern United States of America
Energy Technology Data Exchange (ETDEWEB)
Kumai, M.
1961-01-01
Snow crystals are born at high altitudes and grow into various forms while falling through the atmosphere. In this research work, the relations observed among snow crystals were crystal form, nucleus, and temperature and humidity of the mother cloud based on radiosonde sounding data. Almost all crystal forms which are shown in ''snow crystals'' were observed in a winter season at Houghton (Keweenaw field station), Michigan which is situated on a small peninsula along the southern shore of Lake Superior. Previously there have been no data for the formation of pyramid-shaped snow crystals in natural conditions. It was found that the pyramid-shaped crystals were formed in the clouds at temperatures between -6C and -10C. This coincides with the condition of growth of artificial snow crystals of the Cup and Scroll type. Needle crystals are made in the temperatures between -4c and -6.5c; pyramids, bullets, and columns, between -6C and -10C; hexagonal plates between -8C and 12.6C; and dendritic forms between -14C and -16C. Three hundred snow crystals were collected; successful electron micrographs were obtained of the center nucleus of 271 of these. The nucleus of snow crystals can be classified as clay-mineral particles, hygroscopic particles, combustion products, microorganism and unknown (unidentified) materials. Clay-mineral nuclei accounted for 87 percent, and no nuclei 1 percent of the sample. A relation was found between the sizes of snow-crystal nuclei and the snow-crystal forms. The size of the maximum frequency of needle-crystal nuclei is 3.5 micrometers, and that of the hexagonal-crystal nuclei is 1 micrometer. In other words, the sizes of maximum frequency of the nuclei of snow crystals which are formed at warmer temperatures are larger than those at colder temperatures. In this investigation, no relationship between crystal corms and the substances of the nuclei was found.
Buendia, E; Sarsa, A
2004-01-01
Variational wave functions based on a Margenau-Brink cluster model with short range and state dependent correlations, and angular momentum projection are obtained for some nuclei with $12 \\leq A \\leq 16$. The calculations have been carried out starting from the nucleon-nucleon interaction by using the Variational Monte Carlo method. The configuration used consists of three alpha clusters located at the apexes of an equilateral triangle, and an additional cluster, not necessarily of alpha type, forming a tetrahedron. This cluster is located at the top of its height. Short-range and state dependent correlations are included by means of a central Jastrow factor and a linear operatorial correlation factor respectively. Angular momentum projection is performed by using the Peierls-Yoccoz operators. Optimal structures are obtained for all the nuclei studied. Some aspects of our methodology have been tested by comparing with previous calculations carried out without short range correlations. The binding energy, the ...
Role of the Three-Body Interactions in the Ground-States of 3H and 4He Nuclei
Doma, S B
2015-01-01
The role of the three-body interactions in the ground-states of 3H and 4He nuclei has been investigated by using two different methods. Accordingly, the ground-state nuclear wave functions, the binding energies, the root mean-square radii and the first excited-state energies of the 3H and 4He nuclei are investigated by applying the translation invariant shell model with basis functions corresponding to even number of quanta of excitations in the range 0 less than or equal to N less than or equal to 20 and using two residual two-body interactions, given by the first author, together with three-body interaction in the form of a delta force. Furthermore, we have calculated the binding energy and the root mean-square radius of these nuclei by applying the variational Monte Carlo method and using the Reid V_8 two-body potential together with the Urbana model of the three-nucleon interaction.
Contribution to the study of collective states of heavy nuclei by means of coulomb excitation
International Nuclear Information System (INIS)
The following nuclei were excited by protons of 5 MeV maximum energy: 182W - 184W - 186W - 186Os - 188Os - 189Os - 190Os - 192Os - 194Pt - 196Pt - 198Pt - 198Hg - 200Hg - 202Hg - 204Hg - 206Pb. The reduced probabilities of the various transitions were deduced from the coulomb excitation cross-section measurements. For some even-even nuclei two 2 + levels were excited. The properties of the excited levels are interpreted in terms of the collective model. (author)
Investigation of low-spin states in Gd nuclei following (p,t) and (p, d) reactions
Gell, Kristen; Beausang, Cornelius; Good, Erin; Hughes, Richard; Ross, Timothy; Tarlow, Thomas
2012-10-01
The low to medium spin structures of a variety of Gd nuclei with N ˜ 90 were studied following the ^154,155,158Gd(p, d) and (p, t) reactions. The 27 MeV proton beam was provided by the 88-Inch Cyclotron at LBNL. The Silicon Telescope Array for Reaction Studies (STARS) was utilized to detect the outgoing charged particles (providing both reaction selectivity and excitation energy in the residual nucleus) while the clover Ge detectors of the Liberace array measured coincident gamma-rays. Using the energies of known directly populated states in Gd nuclei, the charged particle spectra were internally calibrated. In addition, the data was analyzed in order to determine which energy states in the respective nuclei were directly populated. Furthermore, angular distributions of gamma-rays emitted from ^154Gd(p,t-γ) were studied in order to make spin assignments to levels directly populated by the reactions. The next step in this research will be to further refine spin assignments and to measure the relative cross sections for direct population. This work was partly supported by the US Department of Energy via grant numbers DE-FG52-09NA29454 and DE-FG02-05-ER41379.
Microscopic structure of high-spin vibrational states in superdeformed A=190 nuclei
Energy Technology Data Exchange (ETDEWEB)
Nakatsukasa, Takashi [Chalk River Labs., Ontario (Canada); Matsuyanagi, Kenichi [Kyoto Univ. (Japan); Mizutori, Shoujirou [Oak Ridge National Lab., TN (United States)] [and others
1996-12-31
Microscopic RPA calculations based on the cranked shell model are performed to investigate the quadrupole and octupole correlations for excited superdeformed (SD) bands in even-even A=190 nuclei. The K = 2 octupole vibrations are predicted to be the lowest excitation modes at zero rotational frequency. The Coriolis coupling at finite frequency produces different effects depending on the neutron and proton number of nucleus. The calculations also indicate that some collective excitations may produce moments of inertia almost identical to those of the yrast SD band. An interpretation of the observed excited bands invoking the octupole vibrations is proposed, which suggests those octupole vibrations may be prevalent in even-even SD A=190 nuclei.
Directory of Open Access Journals (Sweden)
P. V. Borisyuk
2016-09-01
Full Text Available In this paper, we discuss an idea of the experiment for excitation of the isomeric transition in thorium-229 nuclei by irradiating with electron beam targets with necessary physical characteristics. The chemical composition and bandgap of ThSi10O22 were determined by X-ray photoelectron spectroscopy and reflection electron energy loss spectroscopy. It was found that the energy gap is equal to 7.7 eV and does not change when the target is exposed to a medium energy electron beam for a long time. This indicates that the compound possesses high electron-beam resistance. A quantitative estimation of the output function of isomeric thorium-229 nuclei generated by interaction of nuclei with the secondary electron flow formed by irradiating the solid-state ThSi10O22-based target is given. The estimation shows that ThSi10O22 is a promising thorium-containing target for investigating excitation of the nuclear low-lying isomeric transition in the thorium-229 isotope using medium-energy electrons.
Borisyuk, P. V.; Vasilyev, O. S.; Lebedinskii, Y. Y.; Krasavin, A. V.; Tkalya, E. V.; Troyan, V. I.; Habibulina, R. F.; Chubunova, E. V.; Yakovlev, V. P.
2016-09-01
In this paper, we discuss an idea of the experiment for excitation of the isomeric transition in thorium-229 nuclei by irradiating with electron beam targets with necessary physical characteristics. The chemical composition and bandgap of ThSi10O22 were determined by X-ray photoelectron spectroscopy and reflection electron energy loss spectroscopy. It was found that the energy gap is equal to 7.7 eV and does not change when the target is exposed to a medium energy electron beam for a long time. This indicates that the compound possesses high electron-beam resistance. A quantitative estimation of the output function of isomeric thorium-229 nuclei generated by interaction of nuclei with the secondary electron flow formed by irradiating the solid-state ThSi10O22-based target is given. The estimation shows that ThSi10O22 is a promising thorium-containing target for investigating excitation of the nuclear low-lying isomeric transition in the thorium-229 isotope using medium-energy electrons.
Nesterenko, V O; Kleinig, W; Jolos, R V; Kvasil, J; Reinhard, P -G
2015-01-01
The lowest quadrupole $\\gamma$-vibrational $K^{\\pi}=2^+$ states in axially deformed rare-earth (Nd, Sm, Gd, Dy, Er, Yb, Hf, W) and actinide (U) nuclei are systematically investigated within the fully self-consistent separable random-phase-approximation (SRPA) based on the Skyrme functional. The energies $E_{\\gamma}$ and reduced transition probabilities $B(E2)$ of $2^+_{\\gamma}$-states are calculated with the Skyrme forces SV-mas10 and SkM$^*$. We demonstrate that the blocking effect in pairing plays an important role. It leads to a systematic downshift of $E_{\\gamma}$ by 0.3-0.5 MeV and thus to a significant improvement of agreement with the experiment, especially in Sm, Gd, Dy, Hf, and W regions. For other isotopic chains, a noticeable overestimation of $E_{\\gamma}$ and too weak collectivity of $2^+_{\\gamma}$-states still persist. It is shown that domains of nuclei with a low and high $2^+_{\\gamma}$-collectivity are related with the structure of the lowest 2-quasiparticle states and maintenance of the Nilsso...
Search for mixed-symmetry states of nuclei in the vicinity of the double-magic nucleus 208Pb
Directory of Open Access Journals (Sweden)
Kocheva D.
2016-01-01
Full Text Available In this work we present the results from two experiments dedicated to search for quadrupolecollective isovector valence-shell excitation, the states with so-called mixed proton-neutron symmetry (MSS, in nuclei around the doubly magic nucleus 208Pb. 212Po was studied in an α-transfer reaction. 204Hg was studied in an inverse kinematics Coulomb excitation reaction on a carbon target. Both experiments provide indications for existence of one-phonon MSSs. Those are the first experimentally identified MSSs in the mass A ≈ 208 region.
The reduced transition probabilities for excited states of rare-earths and actinide even-even nuclei
International Nuclear Information System (INIS)
The theoretical B(E2) ratios have been calculated on DF, DR and Krutov models. A simple method based on the work of Arima and Iachello is used to calculate the reduced transition probabilities within SU(3) limit of IBA-I framework. The reduced E2 transition probabilities from second excited states of rare-earths and actinide even–even nuclei calculated from experimental energies and intensities from recent data, have been found to compare better with those calculated on the Krutov model and the SU(3) limit of IBA than the DR and DF models
Search for mixed-symmetry states of nuclei in the vicinity of the double-magic nucleus
Kocheva D.; Stegmann R.; Rainovski G.; Jolie J.; Pietralla N.; Stahl C.; Petkov P.; Blazhev A.; Hennig A; Bauer C.; Braunroth Th.; Carpenter M.P.; Cortes L.; Dewald A.; Djongolov M.
2015-01-01
In this work we present the results from two experiments dedicated to search for quadrupole-collective isovector valence-shell excitation, the states with so-called mixed proton-neutron symmetry (MSS), in nuclei around the doubly magic nucleus $^{208}$Pb. $^{212}$Po was studied in an α-transfer reaction. $^{204}$Hg was studied in an inverse kinematics Coulomb excitation reaction on a carbon target. Both experiments provide indications for existence of one-phonon MSSs. Those are the first expe...
The reduced transition probabilities for excited states of rare-earths and actinide even-even nuclei
Energy Technology Data Exchange (ETDEWEB)
Ghumman, S. S. [Department of Physics, Sant Longowal Institute of Engineering and Technology (Deemed University), Longowal, Sangrur-148106, Punjab, India s-ghumman@yahoo.com (India)
2015-08-28
The theoretical B(E2) ratios have been calculated on DF, DR and Krutov models. A simple method based on the work of Arima and Iachello is used to calculate the reduced transition probabilities within SU(3) limit of IBA-I framework. The reduced E2 transition probabilities from second excited states of rare-earths and actinide even–even nuclei calculated from experimental energies and intensities from recent data, have been found to compare better with those calculated on the Krutov model and the SU(3) limit of IBA than the DR and DF models.
Mansour, N A
2003-01-01
The results from the cubic polynomial (CP) formula of the square of the angular velocity and the nuclear moments of inertia are compared with those from the variable moment of inertia (VMI) model and the available experimental information on transition energies for yrast line in even-even nuclei. The evaluated model parameters lead to an excellent fit for all energy levels ( I approx 24). The calculated critical spin for backbending in the zeta - omega sup 2 plot is found to be in agreement with the experimental data. (author)
A test experiment for the study of excited states in Z≅56, N≅80 nuclei via deep inelastic reactions
International Nuclear Information System (INIS)
To check the feasibility of deep inelastic heavy-ion reactions in populating the high-spin states in Z ≅56, N ≅ 80 nuclei, a test experiment has been carried out by using the reaction of 410 MeV 82Se + na'tBa. γ-γ coincidence measurements have been performed using in-beam γ spectroscopy techniques. Population cross-section of excited states in both target-like fragments and projectile-like fragments have been estimated. New γ transitions were identified in several target-like fragments. A new level scheme including five new levels has been established for 136Ba. The preliminary results show that deep inelastic heavy-ion reactions are very promising for populating the excited states in the Z ≅ 56, N ≅ 80 region
International Nuclear Information System (INIS)
We present the first systematic calculations based on the angular momentum projection of cranked Slater determinants. We propose the Iy→I scheme, by which one projects the angular momentum I from the one-dimensional cranked state constrained to the average spin projection of y>=I. Calculations performed for the rotational band in 46Ti show that the AMP Iy→I scheme offers a natural mechanism for correcting the cranking moment of inertia at low spins and shifting the terminating state up by ∼2 MeV, in accordance with data. We also apply this scheme to high-spin states near the band termination in A∼44 nuclei and compare results thereof with experimental data, shell-model calculations, and results of the approximate analytical symmetry-restoration method proposed previously
Probing single-particle and collective states in atomic nuclei with Coulomb excitation
DiJulio, Douglas
A series of experiments and developments, related to stable and radioactive isotopes, have been carried out. These studies have focused on measuring the low-lying excitations of spherical and deformed nuclei using electromagnetic (Coulomb) excitation and also on developments in detector technology for upcoming radioactive ion beams facilities. The low-lying excitations in the nuclei 107,109Sn and 107In have been investigated using low-energy Coulomb excitation at the REX-ISOLDE facility at CERN. The measured reduced transition probabilities were compared to predictions of nuclear structure models. In addition, a relativistic Coulomb excitation experiment was carried out using the FRS at GSI with the nucleus 104Sn. These radioactive ion beam experiments provide important constraints for large-scale-shell-model calculations in the region of the doubly magic nucleus 100Sn. A stable Coulomb excitation experiment was also carried out in order to explore the properties of low-lying structures in the nucleus 170Er...
Excited collective states of nuclei within Bohr Hamiltonian with Tietz-Hua potential
Chabab, M; Hamzavi, M; Lahbas, A; Oulne, M
2016-01-01
In this paper, we present new analytical solutions of the Bohr Hamiltonian problem that we derived with the Tietz-Hua potential, here used for describing the {\\beta}-part of the nuclear collective potential plus harmonic oscillator one for the {\\gamma}-part. Also, we proceed to a systematic comparison of the numerical results obtained with this kind of {\\beta}-potential with others which are widely used in such a framework as well as with the experiment. The calculations are carried out for energy spectra and electromagnetic transition probabilities for {\\gamma}-unstable and axially symmetric deformed nuclei. In the same frame, we show the effect of the shape flatness of the {\\beta}-potential beyond its minimum on transition rates calculations.
Ring, P; Lalazissis, G A
1997-01-01
A Fortran program for the calculation of the ground state properties of axially deformed even-even nuclei in the relativistic framework is presented. In this relativistic mean field (RMF) approach a set of coupled differential equations namely the Dirac equation with potential terms for the nucleons and the Glein-Gordon type equations with sources for the meson and the electromagnetic fields are to be solved self-consistently. The well tested basis expansion method is used for this purpose. Accordingly a set of harmonic oscillator basis generated by an axially deformed potential are used in the expansion. The solution gives the nucleon spinors, the fields and level occupancies, which are used in the calculation of the ground state properties.
Sharpey-Schafer, J. F.; Mullins, S. M.; Bark, R. A.; Gueorguieva, E.; Kau, J.; Komati, F.; Lawrie, J. J.; Maine, P.; Minkova, A.; Murray, S. H. T.; Ncapayi, N. J.; Vymers, P.
2008-05-01
The results of our measurements on the yrare states up to spin 20ℏ in 152,154,155Gd, using (α,xn) reactions and the AFRODITE γ-ray spectrometer, are presented. We find that in 155Gd the decay scheme is divided into levels feeding the [505]11/2- band, that is extruded by the prolate deformation from the h11/2 orbital, and levels feeding the i13/2[651]3/2+ intruder orbital and the h9/2[521]3/2- orbital. The decay scheme of 154Gd is very complex. We find no evidence for the existence of β-vibrational levels below 1.5 MeV. We discover that the level scheme can be best understood as a set of collective states built on the ground state configuration |01+> plus a ``congruent'' set of collective states based on the |02+> state at 681 keV. The data suggest that this second vacuum has reduced pairing. Our data do not support IBA and phonon interpretations of these transitional nuclei.
International Nuclear Information System (INIS)
The results of our measurements on the yrare states up to spin 20(ℎ/2π) in 152,154,155Gd, using (α,xn) reactions and the AFRODITE γ-ray spectrometer, are presented. We find that in 155Gd the decay scheme is divided into levels feeding the [505]11/2- band, that is extruded by the prolate deformation from the h11/2 orbital, and levels feeding the i13/2[651]3/2+ intruder orbital and the h9/2[521]3/2- orbital. The decay scheme of 154Gd is very complex. We find no evidence for the existence of β-vibrational levels below 1.5 MeV. We discover that the level scheme can be best understood as a set of collective states built on the ground state configuration |01+> plus a 'congruent' set of collective states based on the |02+> state at 681 keV. The data suggest that this second vacuum has reduced pairing. Our data do not support IBA and phonon interpretations of these transitional nuclei
DEFF Research Database (Denmark)
Dogonowski, Anne-Marie; Siebner, Hartwig R; Sørensen, Per Soelberg;
2013-01-01
controls underwent a 20-minute resting-state fMRI session at 3 Tesla. Independent component analysis was applied to the fMRI data to identify disease-related changes in motor resting-state connectivity. RESULTS: Patients with MS showed a spatial expansion of motor resting-state connectivity in deep...
Investigation of low-spin states in Sm nuclei following (p,t) reactions
Gell, K.; Beausang, C. W.; Simon, A.; Humby, P.; Watwood, N.
2014-09-01
The low spin structures of 152Sm nuclei were studied following the 154Sm(p,t) reactions. The 25 MeV proton beam was provided by the K150 Cyclotron at Texas A&M University. The Silicon Telescope Array for Reaction Studies (STARS) was utilized to detect outgoing charged particles, providing for both reaction selectivity and excitation energy in the residual nucleus. The efficiency of the telescope was about 20% for outgoing charged particles. The clover Ge detectors of the LiTeR (Livermore Texas Richmond) array measured coincident gamma rays with an efficiency of ~5% at 200 keV and ~ 2% at 1332 keV. The angular coverage of the STARS silicon detectors was ~30-60 degrees allowing a measurement of the angular distribution of tritons emitted from the 154Sm nucleus. These were compared to calculated DWBA curves order to make spin assignments for levels directly populated by the reaction. The next step in this research is to begin analysis of angular distributions of the continuum region of higher excitation energies in order to determine a distribution of L-transfer values.
Jin, Guanghao; Yoon, Jin-Hee; Cha, Dongwoo
2008-03-01
We examine the effects of the additional term of the type {\\sim} e^{- \\lambda^{\\prime} N_pN_n} on the recently proposed empirical formula for the lowest excitation energy of the 2+ states in even-even nuclei. This study is motivated by the fact that this term carries the favorable dependence of the valence nucleon numbers dictated by the NpNn scheme. We show explicitly that there is not any improvement in reproducing Ex(2+1) by including the extra NpNn term. However, our study also reveals that the excitation energies Ex(2+1), when calculated by the NpNn term alone (with the mass number A dependent term), are quite comparable to those calculated by the original empirical formula.
Nuclear halo and its scaling laws in the excited states of nuclei near the β-stability line
International Nuclear Information System (INIS)
The excited states of some odd A nuclei near the stability line have been systematically investigated from light to intermediate mass with the spherical relativistic mean field (RMF) model. The ratio between the valence nucleon root-mean-square (RMS) radius and the core rms radius, the separation energy and the density distribution have been deduced as signatures for halo or skin structure. We have presented the scaling laws of the ratio of valence particle rms radii and square-potential radii versus the scaled separation energies. The probability for a valence particle being out of the binding potential has also been extracted. We proposed a relaxed necessary condition for nuclear halo occurrence. (author)
International Nuclear Information System (INIS)
Description of the interplay between different nuclear shapes is an interesting but challenging problem. The original projected shell model (PSM) is applicable to nuclei with fixed shapes. We extend the PSM by superimposing (angular-momentum- and particle-number-) projected product wave functions in the spirit of the generate coordinate method. With this development, the Gd isotopes across the N = 90 region are studied, and the results indicate spectroscopic features of shape phase transition with varying neutron number. In order to illustrate the shape distribution in microscopic wave functions, we introduce a deformation representation and show that the collectively excited Kπ= 0+ states in the Gd isotopes have characters of shape vibration. (authors)
Effect of phonon interaction on the ground state of even-even spherical nuclei
International Nuclear Information System (INIS)
The equations for calculating the energy and the structure of the excited states with the wave function containing one- and two-phonon components are obtained. The phonon correlations in the ground state of the nucleus due to the interaction of the phonon modes excitation are taken into account. The numerical estimations of the phonon correlations influence on the energy of the lowest excited states are given
Mean field description of the ground state of many boson systems relevant to nuclei
International Nuclear Information System (INIS)
In the present paper we give the explicit expressions for the ground state of a many boson system in different mean field approximations, such as Hartree-Bose, Bogoliubov, the particle-hole random phase approximation (RPA), and its coupling with the particle-particle (RPA). The ground states obtained satisfy the requirement that the annihilation operators of the ''elementary excitations'' annihilates them. In all cases the ground state wave functions can be understood as a condensate of pairs of bosons
Skyrme RPA description of γ-vibrational states in rare-earth nuclei
Directory of Open Access Journals (Sweden)
Nesterenko V.O.
2016-01-01
Full Text Available The lowest γ-vibrational states with Kπ = 2+γ in well-deformed Dy, Er and Yb isotopes are investigated within the self-consistent separable quasiparticle random-phase-approximation (QRPA approach based on the Skyrme functional. The energies Eγ and reduced transition probabilities B(E2γ of the states are calculated with the Skyrme force SV-mas10. We demonstrate the strong effect of the pairing blocking on the energies of γ-vibrational states. It is also shown that collectivity of γ-vibrational states is strictly determined by keeping the Nilsson selection rules in the corresponding lowest 2qp configurations.
Skyrme RPA description of γ-vibrational states in rare-earth nuclei
Nesterenko V.O.; Kartavenko V.G.; Kleinig W.; Kvasil J.; Repko A.; Jolos R.V.; Reinhard P.-G.
2016-01-01
The lowest γ-vibrational states with Kπ = 2+γ in well-deformed Dy, Er and Yb isotopes are investigated within the self-consistent separable quasiparticle random-phase-approximation (QRPA) approach based on the Skyrme functional. The energies Eγ and reduced transition probabilities B(E2)γ of the states are calculated with the Skyrme force SV-mas10. We demonstrate the strong effect of the pairing blocking on the energies of γ-vibrational states. It is also shown that collectivity of γ-vibration...
Spectroscopy of quadrupole and octupole states in rare-earth nuclei from a Gogny force
Nomura, K; Robledo, L M
2015-01-01
Collective quadrupole and octupole states are described in a series of Sm and Gd isotopes within the framework of the interacting boson model (IBM), whose Hamiltonian parameters are deduced from mean field calculations with the Gogny energy density functional. The link between both frameworks is the ($\\beta_2\\beta_3$) potential energy surface computed within the Hartree-Fock-Bogoliubov framework in the case of the Gogny force. The diagonalization of the IBM Hamiltonian provides excitation energies and transition strengths of an assorted set of states including both positive and negative parity states. The resultant spectroscopic properties are compared with the available experimental data and also with the results of the configuration mixing calculations with the Gogny force within the generator coordinate method (GCM). The structure of excited $0^{+}$ states and its connection with double octupole phonons is also addressed. The model is shown to describe the empirical trend of the low-energy quadrupole and o...
International Nuclear Information System (INIS)
The topics presented at the 1989 Joliot-Curie Lectures are reported. Two main subjects were retained: a simplified description of the N-body motion of particles in the quasi-particle configuration; study of the dynamics of nuclear components which are not described by nucleons in their ground state. The following themes were presented: quasiparticles and the Green functions, relativistic aspects of the quasiparticle concept, the dimensions of nucleons in the nuclei and the EMC effect, quarks and gluons in the nuclei, the delta in the nuclei, the strangeness, quasiparticles far from the Fermi sea, diffusion of electrons, stellar evolution and nucleosynthesis
Charmed mesic nuclei Bound D and over D states with 208Pb
Tsushima, K; Thomas, A W; Saitô, K; Landau, Rubin H
1999-01-01
We show that the $D^-$ meson will inevitably form narrow bound states with $^{208}$Pb. The experimental confirmation and comparison with the $\\bar{D}^0$ and $D^0$ will provide distinctive information on the nature of the interaction between the charmed meson and matter.
Study of some excited states in 21Ne-21Na, 18O-18F and 15N-15O nuclei
International Nuclear Information System (INIS)
The study of 21Ne-21Na, 18O-18F and 15N-15O nuclei was performed through proton capture and transfer reactions and allows to determine the spins and parities of some excited states, give the gamma deexcitation schemes of these levels, compute the neutron and proton reduced width γ2sub(n) and γ2sub(p). The levels studied are: in 21Na 4.1520Ne(p,p), (p,p'), (p,p'γ) and (pγ) reactions) and in 21Ne: E(exc)=4.73, 5.69 and 5.78 MeV (20Ne (p,p) reaction); in 18O: E(exc)17O(d,p) reaction); in 15O: 8.92 MeV doublet and 8.98 MeV level (angular correlation 14N(p,γγ) and in 15N: 9.0514N(d,p) reaction). A comparison with theoretical results is discussed and analog states are pointed out
Multi-quasiparticle high-K isomeric states in deformed nuclei
Xu, F. R.; Shi, Y.; Liu, H. L.; Liang, W. Y.; Walker, P. M.; Dracoulis, G. D.
2016-09-01
In the past years, we have made many theoretical investigations on multi-quasiparticle high-K isomeric states. A deformation-pairing-configuration self-consistent calculation has been developed by calculating a configuration-constrained multi-quasiparticle potential energy surface (PES). The specific single-particle orbits that define the high-K configuration are identified and tracked (adiabatically blocked) by calculating the average Nilsson numbers. The deformed Woods-Saxon potential was taken to give single-particle orbits. The configuration-constrained PES takes into account the shape polarization effect. Such calculations give good results on excitation energies, deformations and other structure information about multi-quasiparticle high-K isomeric states. Many different mass regions have been investigated.
Octupole correlations in positive-parity states of rare-earth and actinide nuclei
Directory of Open Access Journals (Sweden)
Spieker M.
2015-01-01
Full Text Available In this contribution, further evidence of the importance of multiphonon-octupole excitations to describe experimental data in the rare earths and actinides will be presented. First, new results of a (p, t experiment at the Q3D magnetic spectrograph in Munich will be discussed, which was performed to selectively excite Jπ = 0+ states in 240Pu. spdf interacting boson model (IBM calculations suggest that the previously proposed double-octupole phonon nature of the Jπ = 0+2 state is not in conflict with its strong (p, t population. Second, the framework of the IBM has been adopted for the description of experimental observables related to octupole excitations in the rare earths. Here, the IBM is able to describe the signature splitting for positiveand negative-parity states when multi-dipole and multi-octupole bosons are included. The present study might support the idea of octupole-phonon condensation at intermediate spin (Jπ = 10+ leading to the change in yrast structure observed in 146Nd.
Energy Technology Data Exchange (ETDEWEB)
Ching, Ping Pui; Zaveri, Rahul A.; Easter, Richard C.; Riemer, Nicole; Fast, Jerome D.
2016-05-27
Light absorption by black carbon (BC) particles emitted from fossil fuel combustion depends on the how thickly they are coated with non-refractory species such as ammonium, sulfate, nitrate, organics, and water. The cloud condensation nuclei (CCN) activation property of a particle depends on its dry size and the hygroscopicities of all the individual species mixed together. It is therefore necessary to represent both size and mixing state of aerosols to reliably predict their climate-relevant properties in atmospheric models. Here we describe and evaluate a novel sectional framework in the Model for Simulating Aerosol Interactions and Chemistry, referred to as MOSAIC-mix, that represents the mixing state by resolving aerosol dry size (Ddry), BC dry mass fraction (wBC), and hygroscopicity (κ). Using ten idealized urban plume scenarios in which different types of aerosols evolve over 24 hours under a range of atmospherically relevant environmental conditions, we examine errors in CCN concentrations and optical properties with respect to a more explicit aerosol mixing state representation. We find that only a small number of wBC and κ bins are needed to achieve significant reductions in the errors, and propose a configuration consisting of 24 Ddry bins, 2 wBC bins, and 2 κ bins that gives 24-hour average errors of about 5% or less in CCN concentrations and optical properties, 3-4 times lower than those from size-only-resolved simulations. These results show that MOSAIC-mix is suitable for use in regional and global models to examine the effects of evolving aerosol mixing states on aerosol-radiation-cloud feedbacks.
In-beam studies of high-spin states of actinide nuclei
Energy Technology Data Exchange (ETDEWEB)
Stoyer, M.A. (Lawrence Berkeley Lab., CA (USA). Nuclear Science Div. California Univ., Berkeley, CA (USA). Dept. of Chemistry)
1990-11-15
High-spin states in the actinides have been studied using Coulomb- excitation, inelastic excitation reactions, and one-neutron transfer reactions. Experimental data are presented for states in {sup 232}U, {sup 233}U, {sup 234}U, {sup 235}U, {sup 238}Pu and {sup 239}Pu from a variety of reactions. Energy levels, moments-of-inertia, aligned angular momentum, Routhians, gamma-ray intensities, and cross-sections are presented for most cases. Additional spectroscopic information (magnetic moments, M{sub 1}/E{sub 2} mixing ratios, and g-factors) is presented for {sup 233}U. One- and two-neutron transfer reaction mechanisms and the possibility of band crossings (backbending) are discussed. A discussion of odd-A band fitting and Cranking calculations is presented to aid in the interpretation of rotational energy levels and alignment. In addition, several theoretical calculations of rotational populations for inelastic excitation and neutron transfer are compared to the data. Intratheory comparisons between the Sudden Approximation, Semi-Classical, and Alder-Winther-DeBoer methods are made. In connection with the theory development, the possible signature for the nuclear SQUID effect is discussed. 98 refs., 61 figs., 21 tabs.
Final-state interaction in semi-inclusive DIS off nuclei
Ciofi degli Atti, C
2003-01-01
The Final-State Interaction (FSI) in Deep-Inelastic Scattering (DIS) of leptons off a nucleus A, due to the propagation of the struck nucleon debris and its hadronization in the nuclear environment is considered. The effective cross-section of such a partonic system with the nucleons of the medium and its time dependence are estimated, for different values of the Bjorken scaling variable, on the basis of a model which takes into account both the production of hadrons due to the breaking of the color string, which is formed after a quark is knocked out off a bound nucleon, as well as the production of hadrons originating from gluon radiation. It is shown that the interaction, the evolution and the hadronization of the partonic system in the nuclear environment can be thoroughly investigated by a new type of semi-inclusive process, denoted A(e,e'(A-1))X, in which the scattered lepton is detected in coincidence with a heavy nuclear fragment, namely a nucleus (A-1) in low energy and momentum states. As a matter o...
Solid state NMR study of quadrupolar nuclei at high magnetic fields
Padro, D
2002-01-01
Solid state sup 4 sup 7 sup , sup 4 sup 9 Ti NMR spectra have been obtained for a large number of titanium oxides at a field of 14.1 T. At this field a usable signal has been obtained in almost all Ti sup 4 sup + compounds investigated allowing reliable measurement of shifts and electric field gradients (EFG) up to 24 MHz. For samples where the efg was less than 5 MHz Magic Angle Spinning at 17 kHz gave extra resolution. The effects of chemical shift anisotropy (DELTA sub c sub s > 150 ppm) were detected and were measured in various cases. In order to investigate the potential of titanium NMR as a structural probe a number of compounds containing titanium in different coordination have been studied. The EFG at TiO sub 4 , TiO sub 5 and TiO sub 6 sites was found to correlate well with the shear strain independent of the structure. The chemical shift in perovskite and related structures varies by approx 160. Results for sup 4 sup 7 sup , sup 4 sup 9 Ti NMR in model compounds where titanium is in 4-fold and 5-fo...
Measurement of lifetimes of high spin states in the N = 106 nuclei {sup 183}Ir and {sup 182}Os
Energy Technology Data Exchange (ETDEWEB)
Ahmad, I.; Blumenthal, D.; Carpenter, M.P. [and others
1995-08-01
Lifetimes of high spin states in the isotones {sup 183}Ir and {sup 182}Os were measured using the Notre Dame plunger device in conjunction with the Argonne Notre Dame {gamma}-ray facility. The aim of these measurements was to determine the deformation-driving properties of the h{sub 9/2} proton intruder orbital by comparing the values of the intrinsic quadrupole moments in the ground state bands in the odd-mass Ir nucleus and the even-even Os core. Levels in these nuclei were populated by the {sup 150}Nd ({sup 37}Cl,4n) and {sup 150}Nd ({sup 36}S,4n) reactions using a {sup 37}Cl beam of 169 MeV and 164-Mev {sup 36}S beam. The {sup 150}Nd target was 0.9-g/cm{sup 2} thick and was prepared by evaporating enriched {sup 150}Nd onto a stretched 1.5-mg/cm{sup 2} gold foil. The target was covered with a layer of a 60-{mu}g/cm{sup 2} Au to prevent its oxidation. Gamma-ray spectra were accumulated for approximately 4 hours for each target-stopper distance. Data were collected for 20 target-stopper distances ranging from 16 {mu}m to 10.4 mm. Preliminary analysis indicates that it will be possible to extract the lifetimes of the levels in the yrast bands up to and including part of the backbending region with sufficient accuracy. Detailed analysis of the data is in progress.
International Nuclear Information System (INIS)
Microscopic model for three-cluster configuration of light nuclei has been formulated in the frameworks of resonating group method in its algebraic version. The model has been applied for the ground states of 6He and 8He in configuration of α-particle plus two n-clusters and α-particle plus two 2n-clusters. The results have been obtained emphasize the importance of three-cluster moving mode for adequate description of nuclear properties, especially neutron halo
Khoa, Dao Tien; Egelhof, Peter; Gales, Sydney; Giai, Nguyen Van; Motobayashi, Tohru
2008-04-01
Studies at the RIKEN RI beam factory / T. Motobayashi -- Dilute nuclear states / M. Freer -- Studies of exotic systems using transfer reactions at GANIL / D. Beaumel et al. -- First results from the Magnex large-acceptance spectrometer / A. Cunsolo et al. -- The ICHOR project and spin-isospin physics with unstable beams / H. Sakai -- Structure and low-lying states of the [symbol]He exotic nucleus via direct reactions on proton / V. Lapoux et al. -- Shell gap below [symbol]Sn based on the excited states in [symbol]Cd and [symbol]In / M. Górska -- Heavy neutron-rich nuclei produced in the fragmentation of a [symbol]Pb beam / Zs. Podolyák et al. -- Breakup and incomplete fusion in reactions of weakly-bound nuclei / D.J. Hinde et al. -- Excited states of [symbol]B and [symbol]He and their cluster aspect / Y. Kanada-En'yo et al. -- Nuclear reactions with weakly-bound systems: the treatment of the continuum / C. H. Dasso, A. Vitturi -- Dynamic evolution of three-body decaying resonances / A. S. Jensen et al. -- Prerainbow oscillations in [symbol]He scattering from the Hoyle state of [symbol]C and alpha particle condensation / S. Ohkubo, Y. Hirabayashi -- Angular dispersion behavior in heavy ion elastic scattering / Q. Wang et al. -- Microscopic optical potential in relativistic approach / Z.Yu. Ma et al. -- Exotic nuclei studied in direct reactions at low momentum transfer - recent results and future perspectives at fair / P. Egelhof -- Isotopic temperatures and symmetry energy in spectator fragmentation / M. De Napoli et al. -- Multi-channel algebraic scattering theory and the structure of exotic compound nuclei / K. Amos et al. -- Results for the first feasibility study for the EXL project at the experimental storage ring at GSI / N. Kalantar-Nayestanaki et al. -- Coulomb excitation of ISOLDE neutron-rich beams along the Z = 28 chain / P. Van Duppen -- The gamma decay of the pygmy resonance far from stability and the GDR at finite temperature / G. Benzoni et al
Collective states of the odd-mass nuclei within the framework of the Interacting Vector Boson Model
Ganev, H. G.
2007-01-01
A supersymmetric extension of the dynamical symmetry group $Sp^{B}(12,R)$ of the Interacting Vector Boson Model (IVBM), to the orthosymplectic group $OSp(2\\Omega/12,R)$ is developed in order to incorporate fermion degrees of freedom into the nuclear dynamics and to encompass the treatment of odd mass nuclei. The bosonic sector of the supergroup is used to describe the complex collective spectra of the neighboring even-even nuclei and is considered as a core structure of the odd nucleus. The f...
International Nuclear Information System (INIS)
The power law suggests that the spin is varied with non integer spin more appropriately than other energy expressions. The PL gives the better fit of the energy because the RMSD is very smaller in comparison to SRF for Nd nuclei
Doma, S B
2002-01-01
Phenomenological nucleon-nucleon interaction consisting of central, tensor, spin-orbit and quadratic spin-orbit terms, with Gaussian radial dependence, are constructed by varying their parameters in order to obtain the best fit between the calculated and the experimental values of the binding energy, the root mean-square radius, the D-state probability, the magnetic dipole moment and the electric quadrupole moment of deuteron. The ground-state nuclear wave function of deuteron is expanded in terms of the translation-invariant shell model basis functions corresponding to the number of quanta of excitation 0 <= N <=10. Moreover, the binding energy, the root mean-square radius and the magnetic dipole moment of the nuclei sup 3 H, sup 4 He, sup 5 He and sup 6 Li are also calculated by using the new interactions. The wave functions of these nuclei are expanded in terms of the basis functions of the translation-invariant shell model with N = 10 for the first tow nuclei, N = 7 for sup 5 he and N = 6 for sup 6 ...
Anharmonic vibrations in nuclei
Fallot, M; Andrés, M V; Catara, F; Lanza, E G; Scarpaci, J A; Chomaz, Ph.
2003-01-01
In this letter, we show that the non-linearitites of large amplitude motions in atomic nuclei induce giant quadrupole and monopole vibrations. As a consequence, the main source of anharmonicity is the coupling with configurations including one of these two giant resonances on top of any state. Two-phonon energies are often lowered by one or two MeV because of the large matrix elements with such three phonon configurations. These effects are studied in two nuclei, 40Ca and 208Pb.
Brown, B.Alex; Schwenk, A.
2014-01-01
We use properties of doubly-magic nuclei and ab-initio calculations of low-density neutron matter to constrain Skyrme equations of state for neutron-rich conditions. All of these properties are consistent with a Skyrme functional form and a neutron-matter equation of state that depends on three parameters. With a reasonable range for the neutron-matter effective mass, the values of the two other Skyrme parameters are well constrained. This leads to predictions for other quantities. The neutro...
Kelkar, N G; Moskal, P
2015-01-01
The possibility for the existence of unstable bound states of the S11 nucleon resonance N$^*$(1535) and nuclei is investigated. These quasibound states are speculated to be closely related to the existence of the quasibound states of the eta mesons and nuclei. Within a simple model for the N N$^*$ interaction involving a pion and eta meson exchange, N$^*$-nucleus potentials for N*-$^3$He and N*-$^{24}$Mg are evaluated and found to be of a Woods-Saxon like form which supports two to three bound states. In case of N*-$^3$He, one state bound by only a few keV and another by 4 MeV is found. The results are however quite sensitive to the N N$^*$ $\\pi$ and N N$^*$ $\\eta$ vertex parameters. A rough estimate of the width of these states, based on the mean free path of the exchanged mesons in the nuclei leads to very broad states with $\\Gamma \\sim$ 80 and 110 MeV for N*-$^3$He and N*-$^{24}$Mg respectively.
Ha, Eunja; Cheoun, Myung-Ki
2012-01-01
With the advent of high analysis technology in detecting the Gamow-Teller (GT) excited states beyond 1 nucleon emission threshold, the quenching of the GT strength to the Ikeda sum rule seems to be recovered by the high-lying GT states. Moreover, in some nuclei, the stronger peaks than any other peaks in lower excited states appear explicitly. We address that these high-lying GT excited states stems from the smearing of the Fermi surface by the increase of the chemical potential due to the deformation within a framework of the deformed quasi-particle random phase approximation (DQRPA). Detailed mechanism leading to the smearing is discussed and comparisons to the available experimental data are shown to nicely explain the strong peaks on the high-lying GT excited states.
International Nuclear Information System (INIS)
4 nuclei of Nickel-48 have been produced in the GANIL accelerator. This nucleus is made up of 28 protons and 20 neutrons, it has at least 10 neutrons less than natural nickel but it is doubly magic: both protons and neutrons are distributed on full shells. It appears as if being doubly magic could compensate for the instability due to the shortage of neutrons. (A.C.)
Błaszczak, Z; Marinova, K; LASER 2006
2007-01-01
7th International Workshop on Application of Lasers in Atomic Nuclei Research, LASER 2004, held in Poznan, Poland, May 29-June 01, 2006 Researchers and PhD students interested in recent results in the nuclear structure investigation by laser spectroscopy, the progress of the experimental technique and the future developments in the field will find this volume indispensable. Reprinted from Hyperfine Interactions (HYPE) Volume ???
Doma, S B
2016-01-01
The method of group theory is applied to investigate the ground and the excited states of the triton and helium nuclei by using the translation invariant shell model with basis functions corresponding to even number of quanta of excitations in the range 0 less than or equal to N less than or equal to 20. Accordingly, the ground and first excited state wave functions and energies, the S, P and D state probabilities, the root mean square radius and the magnetic dipole moment of triton have been investigated. Also, the energies and wave functions of the ground and the even parity excited states and the root mean square radius of helium have been investigated. Two residual two body interactions together with two three nucleon interactions have been used in the calculations. Moreover, the convergence of calculations has been examined by extrapolating the results with N less than or equals to 20 step by step to reach N equals to 30 for the two nuclei.
Indian Academy of Sciences (India)
D I Salmov; T Babacan; A Kücükbursa; S Ünlü; İ Maraṣ
2006-06-01
Within the framework of quasiparticle random phase approximation (QRPA), Pyatov–Salamov method [23] for the self-consistent determination of the isovector effective interaction strength parameter, restoring a broken isotopic symmetry for the nuclear part of the Hamiltonian, is used. The isospin admixtures in the ground state of the parent nucleus, and the isospin structure of the isobar analog resonance (IAR) state were investigated with the inclusion of the pairing correlations between nucleons for the medium and heavy mass regions: 80 < < 90, 102 < < 124, and 204 < < 214. It was determined that the influence of the pairing interaction between nucleons on the isospin admixtures in the ground state and the isospin structure of the IAR state is more pronounced for the light isotopes ( ≈ ) of the investigated nuclei.
Energy Technology Data Exchange (ETDEWEB)
Legoll, F. [Service de Physique Theorique, CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France)
1998-07-22
For nuclei with very high electrical charge, the Coulomb field is expected to drive the protons away from the centre to the surface of the nucleus. Such a nucleus would be no more compact but look like a bubble. The goal of this work is to confirm this idea. We are interested in only the ground state of spherical nuclei. We use the Skyrme potential with the Sly4 parametrization to calculate the mean-field Hamiltonian. Paring correlations are described by a surface-active delta paring interaction. In its ground state the nucleus {sup A=900} X{sub Z=274} is shown to be a bubble. Another stable state is found with a little higher energy: it is also a bubble. (author) 11 refs., 18 figs., 33 tabs.
Theoretical analysis of an Uqp(u2) model for ground-state bands in even-even nuclei
International Nuclear Information System (INIS)
The validity of an Uqp(u2) model for the nuclear rotational spectrum is systematically analysed by investigating the Mallmann plots and fitting the experimental data for the even-even rare-earth and actinide nuclei. The results show that the theoretical values obtained from the Uqp(u2) model are in a good accordance with the experimental findings. Thus the Uqp(u2) model has some advantages over the SUq(2) model as far as energy levels are concerned. Further more, a relationship between the parameters of deformations and the nuclear softness is also established
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Experimental and theoretical aspects of the multiple-quantum magic-angle spinning experiment (MQMAS) are discussed in this review. The significance of this experiment, introduced by Frydman and Harwood, is in its ability to provide high-resolution NMR spectra of half-integer quadrupolar nuclei (I /geq 3/2). This technique has proved to be useful in various systems ranging from inorganic materials to biological samples. This review addresses the development of various pulse schemes aimed at improving the signal-to-noise ratio and anisotropic lineshapes. Representative spectra are shown to underscore the importance and applications of the MQMAS experiment. Refs. 97 (author)
Agbemava, S E; Ring, P
2016-01-01
A systematic investigation of octupole deformed nuclei is presented for even-even systems with $Z\\leq 106$ located between the two-proton and two-neutron drip lines. For this study we use five most up-to-date covariant energy density functionals of different types, with a non-linear meson coupling, with density dependent meson couplings, and with density-dependent zero-range interactions. Pairing correlations are treated within relativistic Hartree-Bogoliubov (RHB) theory based on an effective separable particle-particle interaction of finite range. This allows us to assess theoretical uncertainties within the present covariant models for the prediction of physical observables relevant for octupole deformed nuclei. In addition, a detailed comparison with the predictions of non-relativistic models is performed. A new region of octupole deformation, centered around $Z\\sim 98, N\\sim 196$ is predicted for the first time. In terms of its size in the $(Z,N)$ plane and the impact of octupole deformation on binding e...
Brown, B Alex
2013-01-01
We use properties of doubly-magic nuclei and ab-initio calculations of low-density neutron matter to constrain Skyrme equations of state for neutron-rich conditions. All of these properties are consistent with a Skyrme functional form and a neutron-matter equation of state that depends on three parameters. With a reasonable range for the neutron-matter effective mass, the values of the two other Skyrme parameters are well constrained. This leads to predictions for other quantities. The neutron skins for $^{208}$Pb and $^{48}$Ca are predicted to be 0.182(10) fm and 0.173(5) fm, respectively. Other results including the dipole polarizability are discussed.
Agbemava, S E; Ray, D; Ring, P
2014-01-01
Covariant density functional theory (CDFT) is a modern theoretical tool for the description of nuclear structure phenomena. The current investigation aims at the global assessment of the accuracy of the description of the ground state properties of even-even nuclei. We also estimate {\\it theoretical uncertainties} defined here as the spreads of predictions within four covariant energy density functionals (CEDF) in known regions of the nuclear chart and their propagation towards the neutron drip line. Large-scale axial relativistic Hartree-Bogoliubov (RHB) calculations are performed for all $Z\\leq 104$ even-even nuclei between the two-proton and two-neutron drip lines with four modern covariant energy density functionals such as NL3*, DD-ME2, DD-ME$\\delta$ and DD-PC1. The physical observables of interest include the binding energies, two-particle separation energies, charge quadrupole deformations, isovector deformations, charge radii, neutron skin thicknesses and the positions of the two-proton and two-neutro...
Half-Lives of ground states in Pm and Eu nuclei following the 154,152Sm (p,x) reactions at 25 MeV
Watwood, N. J.; Beausang, C. W.; Humby, P.; Simon, A.; Gell, K.
2014-09-01
The primary experiment was designed to study low/medium spin states in Sm nuclei following the 154,152Sm (p,x) reactions where x = d or t. During the experiment the Sm target was irradiated by a 25 MeV proton beam, provided by the K150 Cyclotron at Texas A&M University, with an average beam current of ~1 nA for about one week. Following the experiment, residual radioactivity in the target was measured in the Environmental Radioactivity Laboratory at the University of Richmond using a 25% efficiency coaxial Ge detector enclosed in a 6-inch thick Pb shield. The gamma ray spectra were internally calibrated using a 152Eu source and the energies of known gamma-rays from the target decays and from long lived environmental radioactivity. The decays of three long lived (~1 month or more) mass A ~ 150 nuclei were identified (148Sm, 148Eu, and 147Eu), and half lives for their beta-decay were (re)measured. Work is still in progress and preliminary results will be presented at the APS conference.
Sun, Xiao-Dong; Guo, Ping; Li, Xiao-Hua
2016-08-01
In this work, we systematically investigate the favored α -decay half-lives and α preformation probabilities of both odd-A and doubly-odd nuclei related to ground and isomeric states around the doubly magic cores at Z =82 , N =82 and at Z =82 , N =126 , respectively, within a two-potential approach from the view of the valence nucleon (or hole). The results show that the α preformation probability is linearly related to NpNn or NpNnI , where Np, Nn, and I are the number of valence protons (or holes), the number of valence neutrons (or holes), and the isospin of the parent nucleus, respectively. Fitting the α preformation probabilities data extracted from the differences between experimental data and calculated half-lives without a shell correction, we give two analytic formulas of the α preformation probabilities and the values of corresponding parameters. Using those formulas and the parameters, we calculate the α -decay half-lives for those nuclei. The calculated results can well reproduce the experimental data.
International Nuclear Information System (INIS)
Vector analyzing powers A(theta) and differential cross sections σ(theta) have been measured, with the use of a polarized proton beam of 22.0 MeV and a magnetic spectrograph, for (p,t) reactions leading to the first-excited 2+ (21+) states of the following eighteen nuclei of N = 50 - 82: sup(92,94,96)Mo, sup(98,100,102)Ru, sup(102,104,106,108)Pd, sup(110,112,114)Cd, 116Sn, sup(120,126,128)Te, and 136Ba. In addition A(theta) and σ(theta) for sup(104,110)Pd(p,t) sup(102,108) Pd(0sub(g)+,21+) transitions have been measured at Esub(p) = 52.2 MeV. The experimental results are analyzed in terms of the first- and second-order DWBA including both inelastic two-step processes and sequential transfer (p,d)(d,t) two-step processes. Inter-ference effect between the direct and the two-step processes is found to play an essential role in the (p,t) reactions. A sum-rule method for calculating the (p,d)(d,t) spectroscopic amplitudes has been developed so as to take into account the ground-state correlation in odd-A nuclei. The nuclear-structure wave functions are constructed under the boson expansion method and the quasiparticle random phase approximation (qp RPA) method by using the monopole-pairing, quadrupole-pairing, and QQ forces. The characteristic features of the experimental A(theta) and σ(theta) are better explained in terms of the boson expansion method than in terms of the qp RPA. Dependence of the (p,t) analyzing powers on the static electric quadrupole moment of the 21+ state is found to be strong because of the reorientation (anharmonic) effect in the 21+ yiedls 21+ transfer process. (J.P.N.)
Octupole shapes in heavy nuclei
International Nuclear Information System (INIS)
Theoretical calculations and measurements show the presence of strong octupole correlations in thecyround states and low-lying states of odd-mass and odd-odd nuclei in the RaPa region. Evidence for octupole correlations is provided by the observation of parity doublets and reductions in M1 matrix elements, decoupling parameters, and Coriolis matrix elements Involving high-j states. Enhancement of E1 transition rates has also been observed for some of the octupole deformed nuclei. The most convincing argument for octupole deformation is provided by the similarities of the reduced alpha decay rates to the two members of parity doublets
International Nuclear Information System (INIS)
Discoveries of many different types of nuclear shape coexistence are being found at both low and high excitation energies throughout the periodic table, as documented in recent reviews. Many new types of shape coexistence have been observed at low excitation energies, for examples bands on more than four different overlapping and coexisting shapes are observed in 185Au, and competing triaxial and prolate shapes in 71Se and 176Pt. Discrete states in super-deformed bands with deformations β 2 ∼ 0.4-0.6, coexisting with other shapes, have been seen to high spin up to 60ℎ in 152Dy, 132Ce and 135Nd. Super-deformed nuclei with N and Z both around 38 and around Z = 38, N ≥ 60. These data led to the discovery of new shell gaps and magic numbers of 38 for N and Z and 60 for N but now for deformed shapes. Marked differences in structure are observed at spins of 6 to 20 in nuclei in this region, which differ by only two protons; for example, 68Ge and 70Se. The differences are thought to be related to the competing shell gaps in these nuclei
Theoretical models for exotic nuclei
Energy Technology Data Exchange (ETDEWEB)
Sagawa, Hiroyuki [RIKEN Nishina Center, Saitama (Japan); University of Aizu, Center for Mathematics and Physics, Fukushima (Japan); Hagino, Kouichi [Tohoku University, Department of Physics, Sendai (Japan); Tohoku University, Research Center for Electron Photon Science, Sendai (Japan); National Astronomical Observatory of Japan, Tokyo (Japan)
2015-08-15
We review various theoretical models which have been used to study the properties of the ground state and excited states of nuclei close to and beyond the neutron and proton drip lines. The validity and limitations of these models are discussed with applications to recent experimental findings such as di-neutron correlations in Borromian nuclei, the soft dipole excitations, direct two-neutron and two-proton decays, and odd-even staggerings of reaction cross sections. The role of isoscalar spin-triplet pairing interaction is also pointed out in the low-lying energy spectra as well as the spin- and isospin-dependent decay rates for N = Z and N = Z + 2 nuclei with mass A < 60. A characteristic feature of the Coulomb energy displacement of the Borromian nucleus {sup 11}Li is discussed in connection to the energies of isobaric analogue states (IAS) of T = 5/2 multiples in the A = 11 systems. (orig.)
International Nuclear Information System (INIS)
The authors have observed the cross section and analyzing-power distributions of 2p-1h configurations from targets of oxygen, calcium, and strontium. Each target isotope was chosen to have the highest filled neutron orbital correspond to an empty proton orbital. Respectively, the observed states are based on the configurations (1d/sub 5/2/)3, (1f/sub 7/2/)3, and (1g/sub 9/2/)3 having spins as large as 13/2+, 19/2-, and 25/2+. From the authors' strontium measurements, they have identified previously unknown 25/2+ and 21/2+ states in 89Zr. Relative cross sections for these two transitions are well reproduced by simple model calculations. The analyzing power distributions for the stretched-state transitions seem to show a yet unexplained mass-independent signature. This past fall the authors carried out measurements on samarium and lead isotopes hoping to identify high-spin states based on (1h/sub 11/2/)3 and (li/sub 13/2/)3 2p-1h configurations. On-line spectra indicate some reaction cross section at the predicted excitation, though experimental energy resolution may prevent identification of particular states. Off-line data analysis is currently under way at IUCF
Ground and excited states of doubly open-shell nuclei from ab initio valence-space Hamiltonians
Stroberg, S R; Holt, J D; Bogner, S K; Schwenk, A
2015-01-01
We present ab initio predictions for ground and excited states of doubly open-shell fluorine and neon isotopes based on chiral two- and three-nucleon interactions. We use the in-medium similarity renormalization group, in both flow-equation and Magnus formulations, to derive mass-dependent sd valence-space Hamiltonians. The experimental ground-state energies are reproduced through neutron number N=14, beyond which a new targeted normal-ordering procedure improves agreement with data and large-scale multi-reference calculations. For spectroscopy, we focus on neutron-rich 23-26F and 24-26Ne isotopes near N=14,16 magic numbers. In all cases we find an agreement with experiment competitive with established phenomenology. Moreover, yrast states are well described in 20Ne and 24Mg, providing an ab initio description of deformation in the medium-mass region.
International Nuclear Information System (INIS)
Chirality has recently been proposed as a novel feature of rotating nuclei [1]. Because the chiral symmetry is dichotomic, its spontaneous breaking by the axial angular momentum vector leads to doublets of closely lying rotational bands of the same parity. To investigate nuclear chirality, next to establish the existence of almost degenerate rotational bands, it is necessary to measure also other observables and compare them to the model predictions. The crucial test for the suggested nuclei as candidates to express chirality is based on precise lifetime measurements. Two lifetime experiments and theoretical approaches for the description of the experimental results will be presented. Lifetimes of exited states in 134Pr were measured [2,3] by means of the recoil distance Doppler-shift and Doppler-shift attenuation techniques. The branching ratios and the electric or magnetic character of the transitions were also investigated [3]. The experiments were performed at IReS, Strasbourg, using the EUROBALL IV spectrometer, in conjunction with the inner bismuth germanate ball and the Cologne coincidence plunger apparatus. Exited states in 134Pr were populated in the fusion-evaporation reaction 119Sn(19F, 4n)134Pr. The possible chiral interpretation of twin bands was investigated in the two-quasiparticle triaxial rotor [1] and interacting boson-fermion-fermion models [4]. Both theoretical approaches can describe the level-scheme of 134Pr. The analysis of the wave functions has shown that the possibility for the angular momenta of the proton, neutron, and core to find themselves in the favorable, almost orthogonal geometry, is present but is far from being dominant [3,5]. The structure is characterized by large β and γ fluctuations. The existence of doublets of bands in 134Pr can be attributed to weak chirality dominated by shape fluctuations. In a second experiment branching ratios and lifetimes in 136Pm were measured by means of the recoil distance Doppler-shift and
An introduction to mesic nuclei
Wilkin, Colin
2016-01-01
There is much speculation and a modest amount of evidence that certain mesons might form quasi-bound states with nuclei to produce really exotic states of matter. For this to be a practical possibility, the interaction between the meson and nucleons at low energies must be strong and attractive and the production rates "healthy". The conditions for this are surveyed for the light mesons. How this might lead to quasi-bound states is then discussed in a few typical cases.
International Nuclear Information System (INIS)
In this talk I discuss properties of hot stellar matter at sub-nuclear densities which is formed in supernova explosions. I emphasize that thermodynamic conditions in this case are rather similar to those created in the laboratory by intermediate-energy heavy-ion collisions. Theoretical methods developed for the interpretation of multi-fragment final states in such reactions can be used also for description of the stellar matter. I present main steps of the statistical approach to the equation of state and nuclear composition, dealing with an ensemble of nuclear species instead of one “average” nucleus. Finally some results of this approach are presented. The emphasis is put on possible formation of heavy and superheavy nuclei. (author)
Venhart, M; Boston, A J; Cocolios, T E; Harkness-Brennan, L J; Herzberg, R -D; Joss, D T; Judson, D S; Kliman, J; Matousek, V; Motycak, S; Page, R D; Patel, A; Petrik, K; Sedlak, M; Veselsky, M
2016-01-01
A new technique of elucidating $\\beta$-decay schemes of isotopes with large density of states at low excitation energies has been developed, in which a Broad Energy Germanium (BEGe) detector is used in conjunction with coaxial hyper-pure germanium detectors. The power of this technique has been demonstrated on the example of 183Hg decay. Mass-separated samples of 183Hg were produced by a deposition of the low-energy radioactive-ion beam delivered by the ISOLDE facility at CERN. The excellent energy resolution of the BEGe detector allowed $\\gamma$ rays energies to be determined with a precision of a few tens of electronvolts, which was sufficient for the analysis of the Rydberg-Ritz combinations in the level scheme. The timestamped structure of the data was used for unambiguous separation of $\\gamma$ rays arising from the decay of 183Hg from those due to the daughter decays.
Neutron scattering on deformed nuclei
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Measurements of neutron elastic and inelastic differential cross sections around 14 MeV for 9Be, C, 181Ta, 232Th, 238U and 239Pu have been analyzed using a coupled channel (CC) formalism for deformed nuclei and phenomenological global optical model potentials (OMP). For the actinide targets these results are compared with the predictions of a semi-microscopic calculation using Jeukenne, Lejeune and Mahaux (JLM) microscopic OMP and a deformed ground state nuclear density. The overall agreement between calculations and the measurements is reasonable good even for the very light nuclei, where the quality of the fits is better than those obtained with spherical OMP
Collective excitations in nuclei
Energy Technology Data Exchange (ETDEWEB)
Chomaz, Ph. [Grand Accelerateur National d`Ions Lourds (GANIL), 14 - Caen (France); Collaboration: La Direction des Sciences de la Matiere du CEA (FR); Le Fonds National de la Recherche Scientifique de Belgique (BE)
1998-12-31
The properties of the nucleus cannot be reduced to the properties of its constituents: it is a complex system. The fact that many properties of the nucleus are consequences of the existence of mean-field potential is a manifestation of this complexity. In particular, the nucleons can thus self-organize in collective motions such as giant resonances. Therefore the study of this collective motions is a very good tool to understand the properties of the nucleus itself. The purpose of this article is to stress some aspects of these collective vibrations. We have studied how an ensemble of fermions as the nucleus can self-organize in collective vibrations which are behaving like a gas of bosons in weak interaction. Understanding of these phenomena remains one of the important subjects of actuality in the context of quantal systems in strong interaction. In particular, the study of the states with one or two vibration quanta provides a direct information on the structure of nuclei close to their ground states. Moreover, some collective states appear to be very robust against the onset of chaos. This is the case of the hot giant dipole built on top of a hot nucleus which seems to survive up to rather high temperatures. Their sudden disappearance is still a subject of controversy. It may be that the mean-field and the associated collective states are playing a crucial role also in catastrophic processes such as the phase-transitions. Indeed, when the system is diluted the collective vibrations may become unstable and it seems that these unstable modes provide a natural explanation to the self organization of the system in drops. Finally, considering the diversity of the different structures of exotic nuclei one may expect new vibration types. All these studies are showing the diversity of the collective motions of strongly correlated quantum systems such as the nucleus but many open questions remain to be solved. (authors) 304 refs., 53 figs., 5 tabs.
Decay of heavy and superheavy nuclei
Indian Academy of Sciences (India)
K P Santhosh
2014-04-01
We present here, an overview and progress of the theoretical works on the isomeric state decay, decay fine structure of even–even, even–odd, odd–even and odd–odd nuclei, a study on the feasibility of observing decay chains from the isotopes of the superheavy nuclei = 115 in the range 271 ≤ ≤ 294 and the isotopes of = 117 in the range 270 ≤ ≤ 301, within the Coulomb and proximity potential model for deformed nuclei (CPPMDN). The computed half-lives of the favoured and unfavoured decay of nuclei in the range 67 ≤ ≤ 91 from both the ground state and isomeric state, are in good agreement with the experimental data and the standard deviation of half-life is found to be 0.44. From the fine structure studies done on various ranges of nuclei, it is evident that, for nearly all the transitions, the theoretical values show good match with the experimental values. This reveals that CPPMDN is successful in explaining the fine structure of even–even, even–odd, odd–even and odd–odd nuclei. Our studies on the decay of the superheavy nuclei 271−294115 and 270−301117 predict 4 chains consistently from 284,285,286115 nuclei and 5 chains and 3 chains consistently from 288−291117 and 292117, respectively. We thus hope that these studies on 284−286115 and 288−292117 will be a guide to future experiments.
Energy Technology Data Exchange (ETDEWEB)
Wloch, Marta [Department of Chemistry, Michigan State University, East Lansing, MI 48824 (United States); Gour, Jeffrey R [Department of Chemistry, Michigan State University, East Lansing, MI 48824 (United States); Piecuch, Piotr [Department of Chemistry, Michigan State University, East Lansing, MI 48824 (United States); Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Dean, David J [Physics Division, Oak Ridge National Laboratory, PO Box 2008, Oak Ridge, TN 37831 (United States); Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996 (United States); Center of Mathematics for Applications, University of Oslo, N-0316 Oslo (Norway); Hjorth-Jensen, Morten [Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Center of Mathematics for Applications, University of Oslo, N-0316 Oslo (Norway); Department of Physics, University of Oslo, N-0316 Oslo (Norway); Papenbrock, Thomas [Physics Division, Oak Ridge National Laboratory, PO Box 2008, Oak Ridge, TN 37831 (United States); Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996 (United States)
2005-08-01
We discuss large-scale ab initio calculations of ground and excited states of {sup 16}O and preliminary calculations for {sup 15}O and {sup 17}O using coupled-cluster methods and algorithms developed in quantum chemistry. By using realistic two-body interactions and the renormalized form of the Hamiltonian obtained with a no-core G-matrix approach, we are able to obtain the virtually converged results for {sup 16}O and promising results for {sup 15}O and {sup 17}O at the level of two-body interactions. The calculated properties other than binding and excitation energies include charge radius and charge form factor. The relatively low costs of coupled-cluster calculations, which are characterized by the low-order polynomial scaling with the system size, enable us to probe large model spaces with up to seven or eight major oscillator shells, for which nontruncated shell-model calculations for nuclei with A = 15-17 active particles are presently not possible.
Sun, Xiao-Dong; Li, Xiao-Hua
2016-01-01
In this work, we systematically investigate the favored $\\alpha$-decay half-lives and $\\alpha$ preformation probabilities of both odd-$A$ and doubly-odd nuclei related to ground and isomeric states around the doubly magic cores at $Z=82$, $N=82$ and at $Z=82$, $N=126$, respectively, within a two-potential approach from the view of the valence nucleon (or hole). The results show that the $\\alpha$ preformation probability is linear related to $N_\\text{p}N_\\text{n}$ or $N_\\text{p}N_\\text{n}I$, where $N_\\text{p}$, $N_\\text{n}$, and $I$ are the number of valence protons (or holes), the number of valence neutrons (or holes), and the isospin of the parent nucleus, respectively. Fitting the $\\alpha$ preformation probabilities data extracted from the differences between experimental data and calculated half-lives without a shell correction, we give two analytic formulas of the $\\alpha$ preformation probabilities and the values of corresponding parameters. Using those formulas and the parameters, we calculate the $\\alp...
Yarmukhamedov, R
2016-01-01
Asymptotic expressions for the radial and full wave functions of a three{body bound halo nuclear system with two charged particles in relative coordinates are obtained in explicit form, when the relative distance between two particles tends to infinity. The obtained asymptotic forms are applied to the analysis of the asymptotic behavior of the three-body (pn?) wave functions for the halo ($E^*=3.562$ MeV, $J^{\\pi}=0^+$, $T=1$) state of $^6$Li derived by D. Baye within the Lagrange-mesh method for two forms of the $\\alpha N$ -potential. The agreement between the calculated wave function and the asymptotic formula is excellent for distances up to 30 fm. Information about the values of the three-body asymptotic normalization functions is extracted. It is shown that the extracted values of the three-body asymptotic normalization function are sensitive to the form of the $\\alpha N$ -potential. The mirror symmetry is revealed for the three-body asymptotic normalization functions derived for the isobaric ($^6$He, $^...
International Nuclear Information System (INIS)
Basing on a phenomenological approach accounting for the shell structure, pair correlations and coherent excitations of vibrational type, the energy dependence is discussed of the coefficient of vibrational level density increase for spherical nuclei with A approximately equal to 60. The relationship found is satisfactorily describing the level density for a number of nuclei, the neutron spectra and excitation functions of the 56Fe(n, 2n)55Fe reaction
Understanding Nuclei in the upper sd - shell
Sarkar, M Saha; Ray, Sudatta; Kshetri, Ritesh; Sarkar, S
2013-01-01
Nuclei in the upper-$sd$ shell usually exhibit characteristics of spherical single particle excitations. In the recent years, employment of sophisticated techniques of gamma spectroscopy has led to observation of high spin states of several nuclei near A$\\simeq$ 40. In a few of them multiparticle, multihole rotational states coexist with states of single particle nature. We have studied a few nuclei in this mass region experimentally, using various campaigns of the Indian National Gamma Array setup. We have compared and combined our empirical observations with the large-scale shell model results to interpret the structure of these nuclei. Indication of population of states of large deformation has been found in our data. This gives us an opportunity to investigate the interplay of single particle and collective degrees of freedom in this mass region.
Jurányi, Z.; Tritscher, T.; Gysel, M.; Laborde, M.; Gomes, L.; Roberts, G.; Baltensperger, U.; Weingartner, E.
2013-07-01
Ambient aerosols are a complex mixture of particles with different physical and chemical properties and consequently distinct hygroscopic behaviour. The hygroscopicity of a particle determines its water uptake at subsaturated relative humidity (RH) and its ability to form a cloud droplet at supersaturated RH. These processes influence Earth's climate and the atmospheric lifetime of the particles. Cloud condensation nuclei (CCN) number size distributions (i.e. CCN number concentrations as a function of dry particle diameter) were measured close to Paris during the MEGAPOLI campaign in January-February 2010, covering 10 different supersaturations (SS = 0.1-1.0%). The time-resolved hygroscopic mixing state with respect to CCN activation was also derived from these measurements. Simultaneously, a hygroscopicity tandem differential mobility analyser (HTDMA) was used to measure the hygroscopic growth factor (ratio of wet to dry mobility diameter) distributions at RH = 90%. The aerosol was highly externally mixed and its mixing state showed significant temporal variability. The average particle hygroscopicity was relatively low at subsaturation (RH = 90%; mean hygroscopicity parameter κ = 0.12-0.27) and increased with increasing dry diameter in the range 35-265 nm. The mean κ value, derived from the CCN measurements at supersaturation, ranged from 0.08 to 0.24 at SS = 1.0-0.1%. Two types of mixing-state resolved hygroscopicity closure studies were performed, comparing the water uptake ability measured below and above saturation. In the first type the CCN counter was connected in series with the HTDMA and and closure was achieved over the whole range of probed dry diameters, growth factors and supersaturations using the κ-parametrization for the water activity and assuming surface tension of pure water in the Köhler theory. In the second closure type we compared hygroscopicity distributions derived from parallel monodisperse CCN measurements and HTDMA measurements
Directory of Open Access Journals (Sweden)
Z. Jurányi
2013-01-01
Full Text Available Ambient aerosols are a complex mixture of particles with different physical and chemical properties and consequently distinct hygroscopic behaviour. The hygroscopicity of a particle determines its water uptake at subsaturated relative humidity (RH and its ability to form a cloud droplet at supersaturated RH. These processes influence the Earth's climate and the atmospheric lifetime of the particles.
Cloud condensation nuclei (CCN number size distributions (i.e. CCN number concentrations as a function of dry particle diameter were measured close to Paris during the MEGAPOLI campaign in January–February 2010 covering 10 different supersaturations (SS = 0.1–1.0%. The time-resolved hygroscopic mixing state with respect to CCN activation was also derived from these measurements. Simultaneously, a Hygroscopicity Tandem Differential Mobility Analyser (HTDMA was used to measure the hygroscopic growth factor (ratio of wet to dry mobility diameter distributions at RH = 90%. The aerosol was highly externally mixed and its mixing state showed significant temporal variability. The average particle hygroscopicity was relatively low at subsaturation, RH = 90% (mean hygroscopicity parameter κ = 0.12–0.27 and increased with increasing dry diameter in the range 35–265 nm. The mean κ value, derived from the CCN measurements at supersaturation, ranged from 0.08 to 0.24 at SS = 1.0–0.%.
Two types of mixing state resolved hygroscopicity closure studies were performed comparing the water uptake ability measured below and above saturation. In the first type the CCN counter was coupled with the HTDMA and closure was achieved over the whole range of probed dry diameters, growth factors and supersaturations using the κ-parameterisation for the water activity and assuming surface tension of pure water in the Köhler theory. In the second closure type we compared hygroscopicity distributions derived from parallel monodisperse CCN measurements
Electron scattering off nuclei
International Nuclear Information System (INIS)
Two recently developed aspects related to the scattering of electrons off nuclei are presented. On the one hand, a model is introduced which emphasizes the relativistic aspects of the problem in the impulse approximation, by demanding strict maintenance of the algebra of the Poincare group. On the other hand, the second model aims at a more sophisticated description of the nuclear response in the case of collective excitations. Basically, it utilizes the RPA formalism with a new development which enables a more careful treatment of the states in the continuum as is the case for the giant resonances. Applications of both models to the description of elastic scattering, inelastic scattering to discrete levels, giant resonances and the quasi-elastic region are discussed. (Author)
Multiple phonon excitation in nuclei
International Nuclear Information System (INIS)
The studies of multiphonon excitations in nuclei are reviewed both from the theoretical and experimental points of view. The presence of giant resonances in nuclei is described in the framework of macroscopic and microscopic models and the relative merits of different probes to excite such states are illustrated. The existence of giant resonances built on excited states is stressed. An exhaustive description of the theoretical estimates of the properties of the multiphonon states is presented. The theory predicts that such multiple collective excitations should closely follow a harmonic pattern. Recent experimental results on the double giant dipole resonance using the (π+π-) double charge exchange reaction are shown. The status of the search for isoscalar multiphonon excitations by means of the strong nuclear potential produced by heavy ions is presented. Conclusions are drawn and new prospects are discussed. (authors) 293 refs., 67 figs., 8 tabs
Moessbauer effects on oriented nuclei
International Nuclear Information System (INIS)
Standard nuclear orientation methods (not sensitive to the polarization) do not give information on the sign of the magnetic moment. Mossbauer effect separates right-hand and left-hand circularly polarized components, thus its detection on oriented nuclei (T approximately 10 mK) gives the sign of the magnetic moment of oriented state. In this thesis we applied this method to study the 3/2- ground states of 191Pt and 193Os, which are in the prolate-oblate transition region, where assignement of experimental levels to theoretical states is often umbiguous. We show that for those nuclei the sign of the magnetic moment is the signature of the configuration, and its determination establishes the correspondance between experimental and theoretical levels
Relativistic symmetry breaking in light kaonic nuclei
Yang, Rong-Yao; Jiang, Wei-Zhou; Xiang, Qian-Fei; Zhang, Dong-Rui; Wei, Si-Na
2014-01-01
As the experimental data from kaonic atoms and $K^{-}N$ scatterings imply that the $K^{-}$-nucleon interaction is strongly attractive at saturation density, there is a possibility to form $K^{-}$-nuclear bound states or kaonic nuclei. In this work, we investigate the ground-state properties of the light kaonic nuclei with the relativistic mean field theory. It is found that the strong attraction between $K^{-}$ and nucleons reshapes the scalar and vector meson fields, leading to the remarkabl...
Phonon operators in deformed nuclei
International Nuclear Information System (INIS)
For the description of the excited states in deformed nuclei new phonon operators are introduced, which depend on the sign of the angular momentum projection onto the symmetry axis of a deformed nucleus. In the calculations with new phonons the Pauli principle is correctly taken into account in the two-phonon components of the wave functions. There is a difference in comparison with the calculation with phonons independent of the sign of the angular momentum projection. The new phonons should be used in deformed nuclei if the Pauli principle is consistently taken into account and in the calculations with the excited state wave functions having the components with more than one phonon operator
Directory of Open Access Journals (Sweden)
Wu C.Y.
2012-02-01
Full Text Available Spectra of γ rays following neutron capture at isolated resonances of 6 stable Gd isotopes were measured with highly segmented BaF2 detector DANCE at the Los Alamos LANSCE spallation neutron source. The main emphasis was put on studying the γ-cascade decay of neutron resonances to get unique information on photon strength. An analysis of the accumulated γ-ray spectra within the extreme statistical model leads to an inescapable conclusion that scissors mode resonances are built not only on the ground-state, but also on excited levels in all product nuclei studied. The results on summed B(M1↑ strength and energy of the scissors mode are compared with systematics of scissors mode parameters for the ground-state transitions deduced from nuclear resonance fluorescence measurements. A specific feature of our experiments is the investigation of scissors mode of odd nuclei, for which the nuclear resonance fluorescence provides only limited information.
Kroll, J.; Baramsai, B.; Becker, J. A.; Bečvář, F.; Bredeweg, T. A.; Couture, A.; Chyzh, A.; Dashdorj, D.; Haight, R. C.; Jandel, M.; Krtička, M.; Mitchell, G. E.; O'Donnell, J. M.; Parker, W.; Rundberg, R. S.; Ullmann, J. L.; Vieira, G. J.; Walker, C. L.; Wilhelmy, J. B.; Wouters, J. M.; Wu, C. Y.
2012-02-01
Spectra of γ rays following neutron capture at isolated resonances of 6 stable Gd isotopes were measured with highly segmented BaF2 detector DANCE at the Los Alamos LANSCE spallation neutron source. The main emphasis was put on studying the γ-cascade decay of neutron resonances to get unique information on photon strength. An analysis of the accumulated γ-ray spectra within the extreme statistical model leads to an inescapable conclusion that scissors mode resonances are built not only on the ground-state, but also on excited levels in all product nuclei studied. The results on summed B(M1)↑ strength and energy of the scissors mode are compared with systematics of scissors mode parameters for the ground-state transitions deduced from nuclear resonance fluorescence measurements. A specific feature of our experiments is the investigation of scissors mode of odd nuclei, for which the nuclear resonance fluorescence provides only limited information.
Phonon operators for deformed nuclei
International Nuclear Information System (INIS)
The mathematical formalism with the phonon operators independent of the signature of the angular momentum projection turns out to be inadequate for describing excited states of deformed nuclei. New phonon operators are introduced which depend on the signature of the angular momentum projection on the symmetry axis of a deformed nucleus. It is shown that the calculations with the new phonons take correctly into account the Pauli principle in two-phonon components of wave functions. The results obtained differ from those given by the phonons independent of the signature of the angular momentum projection. The new phonons must be used in deformed nuclei at taking systematically the Pauli principle into account and in calculations involving wave functions of excited states having components with more than one-phonon operator
Direct Reactions with Exotic Nuclei
International Nuclear Information System (INIS)
We discuss recent work on Coulomb dissociation and an effective-range theory of low-lying electromagnetic strength of halo nuclei. We propose to study Coulomb dissociation of a halo nucleus bound by a zero-range potential as a homework problem. We study the transition from stripping to bound and unbound states and point out in this context that the Trojan-Horse method is a suitable tool to investigate subthreshold resonances
Geometric symmetries in light nuclei
Bijker, Roelof
2016-01-01
The algebraic cluster model is is applied to study cluster states in the nuclei 12C and 16O. The observed level sequences can be understood in terms of the underlying discrete symmetry that characterizes the geometrical configuration of the alpha-particles, i.e. an equilateral triangle for 12C, and a regular tetrahedron for 16O. The structure of rotational bands provides a fingerprint of the underlying geometrical configuration of alpha-particles.
Direct Reactions with Exotic Nuclei
Baur, G
2005-01-01
We discuss recent work on Coulomb dissociation and an effective-range theory of low-lying electromagnetic strength of halo nuclei. We propose to study Coulomb dissociation of a halo nucleus bound by a zero-range potential as a homework problem. We study the transition from stripping to bound and unbound states and point out in this context that the Trojan-Horse method is a suitable tool to investigate subthreshold resonances.
Properties of superheavy nuclei with Z = 124
Mehta, M S; Kumar, Bharat; Patra, S K
2015-01-01
We employ Relativistic Mean Field (RMF) model with NL3 parametrization to investigate the ground state properties of superheavy nucleus, Z = 124. The nuclei selected (from among complete isotopic series) for detailed investigation show that the nucleon density at the center is very low and therefore, these nuclei can be treated as semi-bubble nuclei. The considerable shell gap appears at neutron numbers N = 172, 184 and 198 showing the magicity corresponding to these numbers. The results are compared with the macro-microscopic Finite Range Droplet Model (FRDM) wherever possible.
Coupled-cluster computations of atomic nuclei
Hagen, G; Hjorth-Jensen, M; Dean, D J
2013-01-01
In the past decade, coupled-cluster theory has seen a renaissance in nuclear physics, with computations of neutron-rich and medium-mass nuclei. The method is efficient for nuclei with product-state references, and it describes many aspects of weakly bound and unbound nuclei. This report reviews the technical and conceptual developments of this method in nuclear physics, and the results of coupled-cluster calculations for nucleonic matter, and for exotic isotopes of helium, oxygen, calcium, and some of their neighbors.
International Nuclear Information System (INIS)
The purpose of 1991 Joliot-Curie Summer School is to review the most advances in the understanding of the nuclei physics after the considerable progress in gamma spectroscopy. It covers the following topics: Highly and super-deformed nuclei, nuclear structures, mean-field approach and beyond, fission isomers, nuclear excitations with long lifetime and metal clusters
Collective excitations in nuclei
Energy Technology Data Exchange (ETDEWEB)
Chomaz, Ph
1997-12-31
The properties of the nucleus cannot be reduced to the properties of its constituents: it is a complex system. The fact that many properties of the nucleus are consequences of the existence of mean-field potential is a manifestation of this complexity. In particular the nucleons can thus self-organize in collective motions such as giant resonances. Therefore the study of these collective motions is a very good to understand the properties of the nucleus itself. The purpose of this article was to stress some aspects of these collective vibrations. In particular we have studied how an ensemble of fermions as the nucleus can self-organize in collective vibrations which are behaving like a gas of bosons in weak interaction. The understanding of these phenomena remains one of the important subjects of actually in the context of quantal systems in strong interaction. In particular the study of the states with one or two vibration quanta provides a direct information on the structure if nuclei close to their ground states. (author) 270 refs.
Electric monopole transitions from low energy excitations in nuclei
Wood, J L; De Coster, C; Heyde, Kris L G
1999-01-01
Electric monopole (E0) properties are studied across the entire nuclear mass surface. Besides an introductory discussion of various model results (shell model, geometric vibrational and rotational models, algebraic models), we point out that many of the largest E0 transition strengths, $\\rho^2$(E0), are associated with shape mixing. We discuss in detail the manifestation of E0 transitions and present extensive data for~: single-closed shell nuclei, vibrational nuclei, well-deformed nuclei, nuclei that exhibit sudden ground-state changes, and nuclei that exhibit shape coexistence and intruder states. We also give attention to light nuclei, odd-A nuclei, and illustrate a suggested relation between $\\rho^2$(E0) and isotopic shifts.
Relativistic symmetry breaking in light kaonic nuclei
Yang, Rong-Yao; Xiang, Qian-Fei; Zhang, Dong-Rui; Wei, Si-Na
2014-01-01
As the experimental data from kaonic atoms and $K^{-}N$ scatterings imply that the $K^{-}$-nucleon interaction is strongly attractive at saturation density, there is a possibility to form $K^{-}$-nuclear bound states or kaonic nuclei. In this work, we investigate the ground-state properties of the light kaonic nuclei with the relativistic mean field theory. It is found that the strong attraction between $K^{-}$ and nucleons reshapes the scalar and vector meson fields, leading to the remarkable enhancement of the nuclear density in the interior of light kaonic nuclei and the manifest shift of the single-nucleon energy spectra and magic numbers therein. As a consequence, the pseudospin symmetry is shown to be violated together with enlarged spin-orbit splittings in these kaonic nuclei.
Structure of collective modes in transitional and deformed nuclei
Caprio, M. A.
2005-01-01
The collective structure of atomic nuclei intermediate between spherical and quadrupole deformed structure presents challenges to theoretical understanding. However, models have recently been proposed in terms of potentials which are soft with respect to the quadrupole deformation variable beta. To test these models, information is needed on low-spin states of transitional nuclei. The present work involves measurement of electromagnetic decay properties of low-spin states for nuclei in the A=...
Mančev, Ivan; Milojević, Nenad; Belkić, Dževad
2015-06-01
Single charge exchange in collisions between bare projectiles and heliumlike atomic systems at intermediate and high incident energies is examined by using the four-body formalism of the first- and second-order theories. The main purpose of the present study is to investigate the relative importance of the intermediate ionization continua of the captured electron compared to the usual direct path of the single electron transfer from a target to a projectile. In order to achieve this goal, comprehensive comparisons are made between the four-body boundary-corrected continuum-intermediate-states (BCIS-4B) method and the four-body boundary-corrected first Born (CB1-4B) method. The perturbation potential is the same in the CB1-4B and BCIS-4B methods. Both methods satisfy the correct boundary conditions in the entrance and exit channels. However, unlike the CB1-4B method, the second-order BCIS-4B method takes into account the electronic Coulomb continuum-intermediate states in either the entrance or the exit channel depending on whether the post or the prior version of the transition amplitude is used. Hence, by comparing the results from these two theories, the relative importance of the intermediate ionization electronic continua can be assessed within the four-body formalism of scattering theory. The BCIS-4B method predicts the usual second-order effect through double scattering of the captured electron on two nuclei as a quantum-mechanical counterpart of the Thomas classical two-step, billiard-type collision. The physical mechanism for this effect in the BCIS-4B method is also comprised of two steps such that ionization occurs first. This is followed by capture of the electron by the projectile with both processes taking place on the energy shell. Moreover, the role of the second, noncaptured electron in a heliumlike target is revisited. To this end, the BCIS-4B method describes the effect of capture of one electron by the interaction of the projectile nucleus with
International Nuclear Information System (INIS)
Under the axial symmetry assumption ,the relativistic mean field (RMF) theory has been applied to all even-even nuclei from 8O until 50Sn up to the drip lines. The agreement of the results for the binding energies with the experimental data is within 3 MeV.The comparison of the RMF results and predictions using macroscopic-macroscopic calculation shows large discrepancies for far from the stability line.From the distribution of the deformation on the N-Z plane, it is found that the disappearance of the magi city when neutron numbers are magic as 20,28 and 50. But the magi city remains intact for the proton magic number. The RMF theory predicts a very thick neutron skin for neutron rich nuclei as well as thick proton skin for proton rich nuclei. With triaxial symmetry assumption, the RMF has been also applied to some sulfur isotopes.A smooth transition has been found from the prolate shape at 42-46S to the triaxial shape at 48-52S and then to the oblate shape at 54S and finally to the spherical shape at 56S
International Nuclear Information System (INIS)
A review is made of the present status concerning the production of nuclei above 5 MeV temperature. Considerable progress has been made recently on the understanding of the formation and the fate of such hot nuclei. It appears that the nucleus seems more stable against temperature than predicted by static calculations. However, the occurrence of multifragment production at high excitation energies is now well established. The various experimental features of the fragmentation process are discussed. (author) 59 refs., 12 figs
Alpha-cluster model of atomic nuclei
Energy Technology Data Exchange (ETDEWEB)
Sosin, Zbigniew; Kallunkathariyil, Jinesh [Jagiellonian University, M. Smoluchowski Institute of Physics, Krakow (Poland); Blocki, Jan [NCBJ, Theoretical Physics Division (BP2), Swierk (Poland); Lukasik, Jerzy; Pawlowski, Piotr [IFJ PAN, Krakow (Poland)
2016-05-15
The description of a nuclear system in its ground state and at low excitations based on the equation of state (EoS) around normal density is presented. In the expansion of the EoS around the saturation point, additional spin polarization terms are taken into account. These terms, together with the standard symmetry term, are responsible for the appearance of the α-like clusters in the ground-state configurations of the N=Z even-even nuclei. At the nuclear surface these clusters can be identified as alpha particles. A correction for the surface effects is introduced for atomic nuclei. Taking into account an additional interaction between clusters the binding energies and sizes of the considered nuclei are very accurately described. The limits of the EoS parameters are established from the properties of the α, {sup 3}He and t particles. (orig.)
Static quadrupole moments in 120Te nuclei
International Nuclear Information System (INIS)
In recent years the region in the vicinity of tin isotopes has been intensively investigated both from experimental and theoretical perspectives. In tellurium nuclei with two protons outside the major shell, the partial level schemes are dominated by the 1g7/2 orbit leading to 6+ isomers in the vicinity of N=82 shell closure. At low spin, the Te nuclei are considered to be one of the best examples of quadrupole vibrators. For any nuclei to be vibrational namely three criteria must be satisfied : (i) the R4/2 ratio is equal to 2, (ii) a nearly degenerate two-phonon triplet of 0+, 2+ and 4+ states (iii) collective electric quadrupole transitions between states differing by one phonon and strong hindrance of E2 transition between states differing by more than one phonon
Symmetry energy, unstable nuclei, and neutron star crusts
Iida, Kei
2013-01-01
Phenomenological approach to inhomogeneous nuclear matter is useful to describe fundamental properties of atomic nuclei and neutron star crusts in terms of the equation of state of uniform nuclear matter. We review a series of researches that we have developed by following this approach. We start with more than 200 equations of state that are consistent with empirical masses and charge radii of stable nuclei and then apply them to describe matter radii and masses of unstable nuclei, proton elastic scattering and total reaction cross sections off unstable nuclei, and nuclei in neutron star crusts including nuclear pasta. We finally discuss the possibility of constraining the density dependence of the symmetry energy from experiments on unstable nuclei and even observations of quasi-periodic oscillations in giant flares of soft gamma-ray repeaters.
Symmetry energy, unstable nuclei and neutron star crusts
Energy Technology Data Exchange (ETDEWEB)
Iida, Kei [Kochi University, Department of Natural Science, Kochi (Japan); RIKEN Nishina Center, Saitama (Japan); Oyamatsu, Kazuhiro [RIKEN Nishina Center, Saitama (Japan); Aichi Shukutoku University, Department of Human Informatics, Aichi (Japan)
2014-02-15
The phenomenological approach to inhomogeneous nuclear matter is useful to describe fundamental properties of atomic nuclei and neutron star crusts in terms of the equation of state of uniform nuclear matter. We review a series of researches that we have developed by following this approach. We start with more than 200 equations of state that are consistent with empirical masses and charge radii of stable nuclei and then apply them to describe matter radii and masses of unstable nuclei, proton elastic scattering and total reaction cross sections off unstable nuclei, and nuclei in neutron star crusts including nuclear pasta. We finally discuss the possibility of constraining the density dependence of the symmetry energy from experiments on unstable nuclei and even observations of quasi-periodic oscillations in giant flares of soft gamma-ray repeaters. (orig.)
Production of light nuclei in the thermal and coalescence models
Mrowczynski, Stanislaw
2016-01-01
The thermal model properly describes the yield of light nuclei in relativistic heavy-ion collisions even so the loosely bound sizable nuclei cannot exist in the dense and hot hadron gas. Within the coalescence model, light nuclei are formed at the latest stage of nuclear collisions due to final state interactions. After discussing the models, we derive simple analytic formulas showing that the thermal and coalescence model predictions are quantitatively close to each other.
Energy Technology Data Exchange (ETDEWEB)
Mariji, H. [University of Coimbra, Centro de Fisica Computacional, Department of Physics, Coimbra (Portugal)
2016-04-15
The present work evaluates the effect of gap in the density-dependent one-body momentum distribution, n(k, ρ), at the Fermi surface on the calculation of the single-particle properties of nucleons, i.e., the momentum- and density-dependent single-particle potential and the nucleon effective mass, and also on the calculation of the ground-state binding energy of the selected closed-shell nuclei, i.e., {sup 16}O, {sup 40}Ca, and {sup 56}Ni. In order to do this, n(k, ρ) is constructed by use of the calculations of the lowest-order constrained variational method for the symmetric nuclear matter with the Av{sub 18} potential up to J{sub max} = 2 and 5. It is shown that the gap in n(k, ρ) at the Fermi surface has no significant effect on the calculation of single-particle properties in the case of J{sub max} = 5. In the relevant evaluation of the ground-state binding energy of selected nuclei, it is seen that the binding energy of {sup 16}O, improved by including n(k, ρ), is closer to the experimental data, contrary to {sup 40}Ca and {sup 56}Ni. (orig.)
Level density parameter for nuclei with few nucleons above magic number nuclei Z = 82
International Nuclear Information System (INIS)
Since nuclei with extreme neutron richness formed in collisions, or otherwise, or obtained as fission fragments, may be in an excited state, they require a thermodynamical approach in which both the spin degree of freedom and temperature effects have been incorporated. This is similar to the earlier works where these effects have been incorporated to reproduce microscopic fluctuations in high spin nuclei. This spin degree of freedom inherently involves deformation and structural or shape changes
Energy Technology Data Exchange (ETDEWEB)
Broglia, R.A.
1986-01-01
The dipole giant resonance is reviewed, as it is the only vibration which has been experimentally identified in the decay of hot nuclei. The mechanism of exciting the resonance and the mode of the resonance are described. The methods used to calculate the vibrations from the shell model are discussed, including the Hartree-Fock approximation and random phase approximation. Nuclei formed by compound nuclear reactions, which possess high excitation energy and angular momentum, are considered. It is argued that the stability of the dipole may be used to advantage in the study of other properties of nuclei at high excitation. It is also considered possible that the discussion of the dipole giant resonance may be extended to the gamma decay of the isovector quadrupole vibration. 26 refs., 18 figs. (LEW)
Ab Initio Path to Heavy Nuclei
Binder, Sven; Calci, Angelo; Roth, Robert
2014-01-01
We present the first ab initio calculations of nuclear ground states up into the domain of heavy nuclei, spanning the range from 16-O to 132-Sn based on two- plus three-nucleon interactions derived within chiral effective field theory. We employ the similarity renormalization group for preparing the Hamiltonian and use coupled-cluster theory to solve the many-body problem for nuclei with closed sub-shells. Through an analysis of theoretical uncertainties resulting from various truncations in this framework, we identify and eliminate the technical hurdles that previously inhibited the step beyond medium-mass nuclei, allowing for reliable validations of nuclear Hamiltonians in the heavy regime. Following this path we show that chiral Hamiltonians qualitatively reproduce the systematics of nuclear ground-state energies up to the neutron-rich Sn isotopes.
International Nuclear Information System (INIS)
The present collection of letters from JINR, Dubna, contains seven separate records on kinematic separation and mass analysis of heavy recoiling nuclei, dynamical effects prior to heavy ion fusion, VACTIV-DELPHI graphical dialog based program for the analysis of gamma-ray spectra, irradiation of nuclear emulsions in relativistic beams of 6He and3H nuclei, optical and structural investigations of PLZT x/65/35 (x = 4, 8 %) ferroelectric ceramics irradiated by a high-current pulsed electron beam, the oscillating charge and first evidence for neutrinoless double beta decay
International Nuclear Information System (INIS)
Nuclear structure theories are reviewed concerned with nuclei rotational motion. The development of the deformed nucleus model facilitated a discovery of rotational spectra of nuclei. Comprehensive verification of the rotational scheme and a successful classification of corresponding spectra stimulated investigations of the rotational movement dynamics. Values of nuclear moments of inertia proved to fall between two marginal values corresponding to rotation of a solid and hydrodynamic pattern of an unrotating flow, respectively. The discovery of governing role of the deformation and a degree of a symmetry violence for determining rotational degrees of freedon is pointed out to pave the way for generalization of the rotational spectra
International Nuclear Information System (INIS)
The present collection of letters from JINR, Dubna, contains seven separate records on physics from extra dimensions, new physics in the new millennium with GENIUS: double beta decay, dark matter, solar neutrinos, the (μ-, e+) conversion in nuclei mediated by light Majorana neutrinos, exotic muon-to-positron conversion in nuclei: partial transition sum evaluation by using shell model, solar neutrino problem accounting for self consistent magnetohydrodynamics solution for solar magnetic fields, first neutrino observations from the Sudbury neutrino observatory and status report on BOREXINO and results of the muon-background measurements at CERN
Microscopic properties of superdeformed nuclei
Energy Technology Data Exchange (ETDEWEB)
Karlsson, Lennart B
1999-04-01
Many high spin rotational bands in superdeformed nuclei have been found in the A 140 - 150 region, but so far no linking transitions to known normal-deformed states have been found in these nuclei. Therefore, configuration and spin assignments have to be based on indirect spectroscopic information. Identical bands were first discovered in this region of superdeformed states. At present, some identical bands have also been found at normal deformation, but such bands are more common at superdeformation. Recently lifetime measurements have given relative quadrupole moments with high accuracy. Spectroscopic quantities are calculated using the configuration constrained cranked Nilsson-Strutinsky model with the modified oscillator potential. In a statistical study the occurrence of identical bands is tested. Comparing superdeformed and normal deformed nuclei, the higher possibility for identical bands at superdeformation is understood from calculated reduced widths of the E{sub {gamma}} and J{sup (2)} distributions. The importance of high-N orbitals for identical bands is also discussed. Additivity of electric quadrupole moment contributions in the superdeformed A - 150 region is discussed with the nucleus {sup 152}Dy as a `core`. In analytic harmonic oscillator calculations, the effective electric quadrupole moment q{sub eff}, i.e. the change in the total quadrupole moment caused by the added particle, is expressed as a simple function of the single-particle mass, quadrupole moment q{sub {nu}}. Also in realistic calculations, simple relations between q{sub eff} and q{sub {nu}} can be used to estimate the total electric quadrupole moment, e.g. for the nucleus {sup 142}Sm, by adding the effect of 10 holes, to the total electric quadrupole moment of {sup 152}Dy. Furthermore, tools are given for estimating the quadrupole moment for possible configurations in the superdeformed A - 150 region. For the superdeformed region around {sup 143}Eu, configuration and spin assignments
Fissibility of compound nuclei
Iwata, Yoritaka
2012-01-01
Collisions between $^{248}$Cm and $^{48}$Ca are systematically investigated by time-dependent density functional calculations with evaporation prescription. Depending on the incident energy and impact parameter, fusion, deep-inelastic and fission events are expected to appear. In this paper, a microscopic method of calculating the fissibility of compound nuclei is presented.
Elusive active galactic nuclei
Maiolino, R; Comastri, A; Gilli, R; Nagar, NM; Bianchi, S; Boker, T; Colbert, E; Krabbe, A; Marconi, A; Matt, G; Salvati, M
2003-01-01
A fraction of active galactic nuclei do not show the classical Seyfert-type signatures in their optical spectra, i.e. they are optically 'elusive'. X-ray observations are an optimal tool to identify this class of objects. We combine new Chandra observations with archival X-ray data in order to obtai
Octupole collectivity in nuclei
Butler, P. A.
2016-07-01
The experimental and theoretical evidence for octupole collectivity in nuclei is reviewed. Recent theoretical advances, covering a wide spectrum from mean-field theory to algebraic and cluster approaches, are discussed. The status of experimental data on the behaviour of energy levels and electric dipole and electric octupole transition moments is reviewed. Finally, an outlook is given on future prospects for this field.
Triaxiality in superheavy nuclei
International Nuclear Information System (INIS)
In this work, triaxial degree of freedom is explicitly utilized in calculating alpha decay lifetimes. The synthesis of superheavy nuclei with Z = 114-116 and 118 were detected by their decaying alpha chains with terminating spontaneous fission events. The lifetime of alpha decay chains measured are to be compared with the values evaluated theoretically
Electroweak interactions in nuclei
International Nuclear Information System (INIS)
Topics include: introduction to electroweak theory; the Weinberg-Salam theory for leptons; the Weinberg-Salam theory for hadrons-the GIM mechanism; electron scattering as a probe of the electroweak interaction (observation of PV, the weak interaction for nucleons, and parity violation in atoms); and time reversed invariance and electric dipole moments of nucleons, nuclei, and atoms. 52 references
Hoyer, Paul
1995-01-01
I review hard photon initiated processes on nuclei. The space-time development of the DIS reaction as viewed in the target rest frame qualitatively describes the nuclear shadowing of quark and gluon distributions, although it may be difficult to understand the very weak $Q^2$ dependence of the low $x$ data. The current jet hadron energy distribution at large $\
Physics of the continuum of borromean nuclei
Energy Technology Data Exchange (ETDEWEB)
Vaagen, J.S.; Rogde, T. [Dept. of Physics, Univ. of Bergen (Norway); Danilin, B.V. [RRC The Kurchatov Inst., Kurchatov, Moscow (Russian Federation); Ershov, S.N. [JINR, Dubna, Moscow (Russian Federation); Thompson, I.J. [Dept. of Physics, Univ. of Surrey, Guildford (United Kingdom); Zhukov, M.V. [Chalmers Univ. of Technology and Goeteborg Univ., Goeteborg (Sweden); RNBT Collaboration
1998-06-01
The continuum states of two-neutron halo nuclei are calculated in the method of hyperspherical harmonics. Using DWIA theory appropriate for dilute halo matter we have probed the structure of the low-lying {sup 6}He continuum via calculations of charge-exchange and inelastic scattering. (orig.)
Probing nuclei by stripping them
International Nuclear Information System (INIS)
The towing mode appears in nucleus collisions in which forward moving particles with specific angular correlations are emitted. In fact some particles are extracted from the target and towed along for a short while by the projectile during the collision. This process was discovered at the GANIL accelerator in the nineties. These collisions are peripheral. A simulation has shown that the energy and angle features of the particles emitted depends on their initial quantum state inside the target nucleus just before their emission which means that towing mode can be used as a tool to study quantum states in nuclei and their correlations. Experimental results concerning the following reactions: 11Be + 48Ti and 6He + Pb are presented. (A.C.)
Angular velocity: a new dimension in nuclei
Energy Technology Data Exchange (ETDEWEB)
Diamond, R.M.; Stephens, F.S.
1984-08-09
Nuclei can be studied from their ground states (approx.O(h/2..pi..)) up to angular momenta of order 100 (h/2..pi..), where they are literally pulled apart by centrifugal effects. This range of angular momenta can be viewed as resulting from cranking the nucleus around a rotation axis, where the critical variable is the cranking velocity. The calculated response of nuclei to such an imposed angular velocity corresponds well with recent observations, and includes a rich and varied interplay of collective and single-particle phenomena.
Energetic Nuclei, Superdensity and Biomedicine
Baldin, A. M.
1977-01-01
High-energy, relativistic nuclei were first observed in cosmic rays. Studing these nuclei has provided an opportunity for analyzing the composition of cosmic rays and for experimentally verifying principles governing the behavior of nuclear matter at high and super-high temperatures. Medical research using accelerated nuclei is suggested.…
Acceleration of heavy nuclei in solar flares
International Nuclear Information System (INIS)
The overabundance of heavy nuclei in solar cosmic rays of energy approximately less than 5 MeV/nucleon is explained by taking into account the pre-flare ionization states of these nuclei in the region where they are accelerated. A model is proposed which considers two-step accelerations associated with the initial development of solar flares. The first step is closely related to the triggering process of flares, while the second one starts with the development of the explosive phase. Further ionization of medium and heavy nuclei occurs through their interaction with keV electrons accelerated by the first-step acceleration. It is suggested that the role of these electrons is important in producing fully ionized atoms in the acceleration regions. (U.S.)
Triaxiality in 146,148Sm nuclei
International Nuclear Information System (INIS)
Recently, attempts have been made to use the dynamic pairing plus quadrupole model to evaluate B(E2) values, B(E2) branching ratios, and low-lying energy levels for 146,148Sm nuclei, which are in poor agreement with experiment. Application of the boson expansion technique on 148Sm shows too much splitting and an incorrect order for the quintet states, while other properties have not been discussed. In the present work, 146,148Sm nuclei have been described using an asymmetric rotor model framework. The nonaxiality parameter γ has been evaluated using the energy ration E2+'/E6+. Remarkable success has been achieved in explaining the correct ordering of known low-lying energy levels, B(E2) values, and B(E2) branching ratios, which indicate that the so-called spherical nuclei may be treated as triaxial. (author). 8 refs., 9 tabs., 1 fig
New approaches to studies of exotic nuclei
International Nuclear Information System (INIS)
New generations of 4π gamma-ray detectors, recoil mass spectrometers (RMS), and radioactive beam accelerators will open up many new areas of research, including present inaccessible in-beam and radioactive decay studies of exotic nuclei still farther off stability. The new generation RMS and radioactive beam developments at the Holifield Heavy Ion Research Facility are presented. Current research and further prospects to probe the N -- Z line up to 100Sn are described. Superdeformation in A -- 70 to 190 nuclei is described in terms of its underlying physics of reinforcing proton and neutron shell gaps which lead to new superdeformed, doubly-magic nuclei. Recent results provide new insights into the coexistence of multiple nuclear shapes near the ground states
Pairing correlations in exotic nuclei
Sagawa, H
2012-01-01
The BCS and HFB theories which can accommodate the pairing correlations in the ground states of atomic nuclei are presented. As an application of the pairing theories, we investigate the spatial extension of weakly bound Ne and C isotopes by taking into account the pairing correlation with the Hartree-Fock-Bogoliubov (HFB) method and a 3-body model, respectively. We show that the odd-even staggering in the reaction cross sections of $^{30,31,32}$Ne and $^{14,15,16}$C are successfully reproduced, and thus the staggering can be attributed to the unique role of pairing correlations in nuclei far from the stability line. A correlation between a one-neutron separation energy and the anti-halo effect is demonstrated for $s$- and p-waves using the HFB wave functions. We also propose effective density-dependent pairing interactions which reproduce both the neutron-neutron ($nn$) scattering length at zero density and the neutron pairing gap in uniform matter. Then, we apply these interactions to study pairing gaps in ...
International Nuclear Information System (INIS)
Analysis of E1-transitions (ΔK=1) of the 5/2-(512)↔7/2+(633)type, which are observed in odd-neutron nuclei of rare earth elements 165Dy, 167,169Er, 169,171,173Yb, 173,175Hf, 173,175W is carried out in this paper. Comparison of the experimental values of probabilities of this type E1-transitions shows considerable fluctuations of their values. The values of experimental and theoretical (at different approximations) probabilities given for E1-transitions of the type investigated are presented in tables. Analysis carried out for probabilities of E1-transitions of the type investigated showed that, besides including pairing interaction, which plays in this case an important role, consequently calculation in the framework of the non-adiabatic rotational model taking into account state Coriolis mixing is necessary
Energy Technology Data Exchange (ETDEWEB)
Huerstel, A
2002-11-01
This thesis is devoted to the study of very neutron deficient nuclei in the lead region of the nuclear chart and more precisely to the investigation of the single particle states and collective properties of the {sup 187,189}Bi isotopes by gamma-ray spectroscopy. These nuclei were produced via fusion-evaporation reaction induced by a krypton beam on a silver target. In this mass region, the cross section for producing these nuclei are very low, of the order of a few micro-barns, making experimental studies very difficult. The identification of the nuclei was done using the very powerful RDT (Recoil Decay Tagging) technique, based on the selection of the isotopes through their characteristic alpha-particle decays. The experiments were performed at the university of Jyvdskyla (Finland) with the facility combining the gamma-ray spectrometer JUROSPHERE and the magnetic gas-filled separator RITU. Isomeric states were observed in both nuclei and their life-times measured. The systematics of individual proton states in odd-mass bismuth isotopes have been reproduced with a shell model up to 20 neutrons away from the valley of stability. Furthermore, rotational bands, a signature of collective nuclear motion, have been established for the first time in these nuclei. The interpretation of these results led to the conclusion that {sup 187,189}Bi have a prolate shape at low excitation energy, unlike the heavier bismuth isotopes which have been interpreted to have oblate deformation, implying a shape transition in this mass region. Hartree-Fock-Bogolyubov calculations are consistent with the experimental indication of shape coexistence, as seen in the neighbouring even-even lead nuclei. (author)
A new spin-oriented nuclei facility: POLAREX
Directory of Open Access Journals (Sweden)
Etilé A.
2014-03-01
Full Text Available Using the On-Line Nuclear Orientation method, POLAREX (POLARization of EXotic nuclei is a new facility allowing to study the anisotropic decay of spin-oriented nuclei. Based on the combination of on-line implantation of radioactive nuclei with Low Temperature Nuclear Orientation technique and Nuclear Magnetic Resonance, POLAREX allows to measure nuclear electromagnetic moments and ground-state spins, in the aim to get information about the wave function composition of the nuclear state. Polarized nuclei can also be used to study fundamental interactions involving nuclear β-decay asymmetries. The POLAREX infrastructure will be installed at Accélérateur Linéaire auprés du Tandem d’Orsay in order to study neutron-rich nuclei, some of which have not been studied yet. Will be presented here, all the possibilities of this new facility and a non exhaustive scientific program.
A new spin-oriented nuclei facility: POLAREX
International Nuclear Information System (INIS)
Using the On-Line Nuclear Orientation method, POLAREX (Polarization of Exotic nuclei) is a new facility allowing to study the anisotropic decay of spin-oriented nuclei. Based on the combination of on-line implantation of radioactive nuclei with Low Temperature Nuclear Orientation technique and Nuclear Magnetic Resonance, POLAREX allows the measurement of nuclear electromagnetic moments and ground-state spins, in the aim to get information about the wave function composition of the nuclear state. Polarized nuclei can also be used to study fundamental interactions involving nuclear β-decay asymmetries. The POLAREX infrastructure will be installed at the linear accelerator in Orsay in order to study neutron-rich nuclei, some of which have not been studied yet. Will be presented here, all the possibilities of this new facility and a non exhaustive scientific program. The first experiment will be the nuclear magnetic moment measurement of 125Sb as final commissioning
Spectroscopic Studies of Exotic Nuclei at ISOLDE
2002-01-01
Experiment IS50 is designed to: a) Investigate the full range of the @b strength function of heavy (A~$>$~48)~K nuclei b)~Study the decay of isomeric states in n-deficient bromine nuclei (A~=~72 and 70). The heavy K isotopes appeared to have complex decay schemes, including feeding by the @b-decay of levels having open neutron channels (Beta decay energy Q(@b) exceeds neutron binding energy S^n); in addition, a large fraction of the delayed transitions populate excited levels in the daughter nuclei. The allowed @b-decay selects states in the daughter nucleus with wave functions having a large overlap with the initial state. Hence, the @b strength functions, deduced from these deca reveal simple structures correlated to the particle-hole excitation energies in the Ca nuclei. These results are valuable for the application of the shell-model calculations far from stability. The delayed neutron spectra are measured with a large area curved scintillator in coincidence either with high resolution Ge(Li) detectors, ...
Van Isacker, P
2010-01-01
The use of dynamical symmetries or spectrum generating algebras for the solution of the nuclear many-body problem is reviewed. General notions of symmetry and dynamical symmetry in quantum mechanics are introduced and illustrated with simple examples such as the SO(4) symmetry of the hydrogen atom and the isospin symmetry in nuclei. Two nuclear models, the shell model and the interacting boson model, are reviewed with particular emphasis on their use of group-theoretical techniques.
Effenberger, M.; Mosel, U.
1997-01-01
We calculate the total photoabsorption cross section and cross sections for inclusive pion and eta photoproduction in nuclei in the energy range from 300 MeV to 1 GeV within the framework of a semi-classical BUU transport model. Besides medium modifications like Fermi motion and Pauli blocking we focus on the collision broadening of the involved resonances. The resonance contributions to the elementary cross section are fixed by fits to partial wave amplitudes of pion photoproduction. The cro...
Quasifree kaon photoproduction on nuclei
Energy Technology Data Exchange (ETDEWEB)
Frank Lee; T. MART; Cornelius Bennhold; Lester Wright
2001-12-01
Investigations of the quasifree reaction A({gamma}, K Y)B are presented in the distorted wave impulse approximation (DWIA). For this purpose, we present a revised tree-level model of elementary kaon photoproduction that incorporates hadronic form factors consistent with gauge invariance, uses SU(3) values for the Born couplings and uses resonances consistent with multi-channel analyses. The potential of exclusive quasifree kaon photoproduction on nuclei to reveal details of the hyperon-nucleus interaction is examined. Detailed predictions for the coincidence cross section, the photon asymmetry, and the hyperon polarization and their sensitivities to the ingredients of the model are obtained for all six production channels. Under selected kinematics these observables are found to be sensitive to the hyperon-nucleus final state interaction. Some polarization observables are found to be insensitive to distortion effects, making them ideal tools to search for possible medium modifications of the elementary amplitude.
Relativistic Brueckner-Hartree-Fock theory for finite nuclei
Shen, Shihang; Liang, Haozhao; Meng, Jie; Ring, Peter; Zhang, Shuangquan
2016-01-01
Starting with a bare nucleon-nucleon interaction, for the first time the full relativistic Brueckner-Hartree-Fock equations are solved for finite nuclei in a Dirac-Woods-Saxon basis. No free parameters are introduced to calculate the ground-state properties of finite nuclei. The nucleus $^{16}$O is investigated as an example. The resulting ground-state properties, such as binding energy and charge radius, are considerably improved as compared with the non-relativistic Brueckner-Hartree-Fock results and much closer to the experimental data. This opens the door for \\emph{ab initio} covariant investigations of heavy nuclei.
Description of deformed nuclei in the sdg boson model
S. C. Li; Kuyucak, S.
1996-01-01
We present a study of deformed nuclei in the framework of the sdg interacting boson model utilizing both numerical diagonalization and analytical $1/N$ expansion techniques. The focus is on description of high-spin states which have recently become computationally accessible through the use of computer algebra in the $1/N$ expansion formalism. A systematic study is made of high-spin states in rare-earth and actinide nuclei.
A study of strange-, charmed, and beauty nuclei
International Nuclear Information System (INIS)
An analyses is made of the bound states of nuclei in the strange-, charm-, and beauty sector using a spin-dependent Gaussian two-body interaction in the microscopic formalism. Coulomb corrections are also included for the charmed nuclei. Our simple model is in reasonable agreement with other existing theoretical and experimental results and it predicts many new bound states. (author). 21 refs, 2 figs, 10 tabs
Description of deformed nuclei in the sdg boson model
Li, S C
1996-01-01
We present a study of deformed nuclei in the framework of the sdg interacting boson model utilizing both numerical diagonalization and analytical 1/N expansion techniques. The focus is on description of high-spin states which have recently become computationally accessible through the use of computer algebra in the 1/N expansion formalism. A systematic study is made of high-spin states in rare-earth and actinide nuclei.
Incoherent rho^0 electroproduction off nuclei
Falter, T; Mosel, U
2003-01-01
In the present paper we investigate incoherent rho^0 electroproduction off complex nuclei. We derive a novel, simple expression for the incoherent electroproduction cross section in which one can clearly separate the final state interactions of the reaction products from the 'initial state interactions' of the photon that give rise to nuclear shadowing. In the special case of purely absorptive final state interactions we deduce from our expression the known Glauber result. A more realistic treatment of the final state interactions within a transport model is then used to compare our predictions with experimental data from the HERMES experiment.
Blandford, RD; Woltjer, L
1990-01-01
Starting with this volume, the Lecture Notes of the renowned Advanced Courses of the Swiss Society for Astrophysics and Astronomy will be published annually. In each course, three extensive lectures given by leading experts in their respective fields cover different and essential aspects of the subject. The 20th course, held at Les Diablerets in April 1990, dealt with current research on active galactic nuclei; it represents the most up-to-date views on the subject, presented with particular regard for clarity. The previous courses considered a wide variety of subjects, beginning with ""Theory
Beckmann, Volker
2012-01-01
This AGN textbook includes phenomena based on new results in the X-Ray domain from new telescopes such as Chandra and XMM Newton not mentioned in any other book. Furthermore, it considers also the Fermi Gamma Ray Space Telescope with its revolutionary advances of unprecedented sensitivity, field of view and all-sky monitoring. Those and other new developments as well as simulations of AGN merging events and formations, enabled through latest super-computing capabilities. The book gives an overview on the current knowledge of the Active Galacitc Nuclei phenomenon. The spectral energy d
Effenberger, M.; Hombach, A; Teis, S.; Mosel, U.
1996-01-01
We calculate the total photoabsorption cross section on nuclei in the energy range from 300 MeV to 1 GeV within the framework of a semi-classical phase space model. Besides medium modifications like Fermi motion and Pauli blocking we focus on the collision broadening of the involved resonances. The resonance contributions to the elementary cross section are fixed by fits to partial wave amplitudes of pion photoproduction. The cross sections for $N \\, R \\to N \\, N$, needed for the calculation ...
Symmetries in atomic nuclei from isospin to supersymmetry
Frank, Alejandro; Van Isacker, Pieter
2009-01-01
Symmetries in Atomic Nuclei aims to present an overview of recent applications of symmetry to the description of atomic nuclei. Special care is given to a pedagogical introduction of symmetry concepts using simple examples. After a historical overview of the applications of symmetry in nuclear physics, progress in the field during the last decade is reviewed. Special emphasis is put on the introduction of neutron-proton and boson-fermion degrees of freedom. Their combination leads to a supersymmetric description of pairs and quartets of nuclei. Both theoretical aspects and experimental signatures of dynamical (super)symmetries are carefully discussed. Case studies show how these symmetries are displayed by real atomic nuclei which have been studied experimentally using state-of-the art spectroscopy. Symmetries in Atomic Nuclei focuses on nuclear structure physics and has been written by active investigators in the field, but its scope is wider and is intended for final-year or post-graduate students and resea...
Quadrupole moments of odd-odd near-magic nuclei
Directory of Open Access Journals (Sweden)
Achakovskiy O.
2012-12-01
Full Text Available Ground state quadrupole moments of odd-odd near-double-magic nuclei are calculated in the approximation of non-interacting odd neutron and odd proton. Under such a simple approximation the problem is reduced to the calculations of quadrupole moments of corresponding odd-even nuclei. These calculations are performed within the self-consistent Theory of Finite Fermi Systems based on the Energy Density Functional by Fayans et al. with the known DF3-a parameters. A reasonable agreement with the available experimental data is obtained for odd-odd nuclei and odd near-magic nuclei investigated. The self-consistent approach under consideration allowed us to predict the unknown quadrupole moments of odd-even and odd-odd nuclei near the double-magic 56,78Ni, 100,132Sn nuclides.
Schild, Rudolph E.; Leiter, Darryl J.; Robertson, Stanley L.
2008-03-01
We show how direct microlensing-reverberation analysis performed on two well-known quasars (Q2237, the Einstein Cross, and Q0957, the Twin) can be used to observe the inner structure of two quasars which are in significantly different spectral states. These observations allow us to measure the detailed internal structure of Q2237 in a radio-quiet high-soft state, and compare it to Q0957 in a radio-loud low-hard state. When taken together we find that the observed differences in the spectral states of these two quasars can be understood as being due to the location of the inner radii of their accretion disks relative to the co-rotation radii of the magnetospheric eternally collapsing objects (MECO) in the centers of these quasars. The radiating structures observed in these quasars are associated with standard accretion disks and outer outflow structures, where the latter are the major source of UV-optical continuum radiation. While the observed inner accretion disk structure of the radio-quiet quasar Q2237 is consistent with either a MECO or a black hole, the observed inner structure of the radio-loud quasar Q0957 can only be explained by the action of the intrinsic magnetic propeller of a MECO with its accretion disk. Hence a simple and unified answer to the long-standing question: "Why are some quasars radio loud?" is found if the central objects of quasars are MECO, with radio-loud and radio-quiet spectral states similar to the case of galactic black hole candidates.
Ho, L C; Sargent, W L W; Ho, Luis C.; Filippenko, Alexei V.; Sargent, Wallace L. W.
1996-01-01
We describe a new sample of Seyfert nuclei discovered during the course of an optical spectroscopic survey of nearby galaxies. The majority of the objects, many recognized for the first time, have luminosities much lower than those of classical Seyferts and populate the faint end of the AGN luminosity function. A significant fraction of the nuclei emit broad H-alpha emission qualitatively similar to the broad lines seen in classical Seyfert 1 nuclei and QSOs.
Electron scattering for exotic nuclei
Indian Academy of Sciences (India)
Toshimi Suda
2014-11-01
A brand-new electron scattering facility, the SCRIT Electron Scattering Facility, will soon start its operation at RIKEN RI Beam Factory, Japan. This is the world’s first electron scattering facility dedicated to the structure studies of short-lived nuclei. The goal of this facility is to determine the charge density distributions of short-lived exotic nuclei by elastic electron scattering. The first collision between electrons and exotic nuclei will be observed in the year 2014.
Elusive Active Galactic Nuclei
Maiolino, R; Gilli, R; Nagar, N M; Bianchi, S; Böker, T; Colbert, E; Krabbe, A; Marconi, A; Matt, G; Salvati, M
2003-01-01
A fraction of active galactic nuclei do not show the classical Seyfert-type signatures in their optical spectra, i.e. they are optically "elusive". X-ray observations are an optimal tool to identify this class of objects. We combine new Chandra observations with archival X-ray data in order to obtain a first estimate of the fraction of elusive AGN in local galaxies and to constrain their nature. Our results suggest that elusive AGN have a local density comparable to or even higher than optically classified Seyfert nuclei. Most elusive AGN are heavily absorbed in the X-rays, with gas column densities exceeding 10^24 cm^-2, suggesting that their peculiar nature is associated with obscuration. It is likely that in elusive AGN, the nuclear UV source is completely embedded and the ionizing photons cannot escape, which prevents the formation of a classical Narrow Line Region. Elusive AGN may contribute significantly to the 30 keV bump of the X-ray background.
Few-Body Models of Light Nuclei
Ershov, S. N.; Vaagen, J. S.; Zhukov, M. V.
2015-06-01
Experiments confirm a variety of cluster structures in many light nuclei. The observation of nuclear halos at drip-lines has accentuated the question of the degrees of freedom for bound and low-lying continuum states. In these cases the many-body dynamics of nuclear structure may be well approximated by few-body cluster models that often suggest conceptually simple approaches explaining successfully many features of light nuclei. Thus few-body cluster models have been successfully used for description of the nuclear structure of weakly bound halo nuclei and their emergent cluster degrees of freedom. They have attractive features supplying in a most transparent way the asymptotic behavior and continuum properties of weakly bound systems. Such models assume a separation in internal cluster (core) degrees of freedom and the relative motion of few-body constituents. Such separation is only an approximation, and low-lying states appear where the core cannot be considered as inert system and additional degrees of freedom connected to excited core states have to be taken into account. For fixed total angular momentum a coupling to excited core states having different spins involves additional partial waves into the consideration. This allows to account for some emergent (collective) core degrees of freedom and gives a more realistic description of nuclear properties. It is an analogue to increasing the number of shells within the framework of shell-model approaches. Some examples from recent nuclear structure exploration within few-body halo cluster models are presented.
Liang, Jie; Cao, Youfang; Gürsoy, Gamze; Naveed, Hammad; Terebus, Anna; Zhao, Jieling
2016-01-01
Genome sequences provide the overall genetic blueprint of cells, but cells possessing the same genome can exhibit diverse phenotypes. There is a multitude of mechanisms controlling cellular epigenetic states and that dictate the behavior of cells. Among these, networks of interacting molecules, often under stochastic control, depending on the specific wirings of molecular components and the physiological conditions, can have a different landscape of cellular states. In addition, chromosome folding in three-dimensional space provides another important control mechanism for selective activation and repression of gene expression. Fully differentiated cells with different properties grow, divide, and interact through mechanical forces and communicate through signal transduction, resulting in the formation of complex tissue patterns. Developing quantitative models to study these multi-scale phenomena and to identify opportunities for improving human health requires development of theoretical models, algorithms, and computational tools. Here we review recent progress made in these important directions. PMID:27480462
Population of rotational bands in superheavy nuclei
Directory of Open Access Journals (Sweden)
Antonenko N.V.
2012-02-01
Full Text Available Using the statistical approach, we study the population of ground-state rotational bands of superheavy nuclei produced in the fusion-evaporation reactions 208Pb(48Ca, 2n254No, 206Pb(48Ca, 2n252No, and 204Hg(48Ca, 2n250Fm. We calculate relative intensities of E2-transitions between the rotational states and entry spin distributions of the residual nuclei, evaporation residue cross sections, and excitation functions for these reactions. Fermi-gas model is used for the calculation of level density, and damping of shell effects both with excitation energy and angular momentum is taking into account. The results are in a good agreement with the experiment data.
Gamma spectroscopy of neutron rich actinide nuclei
Energy Technology Data Exchange (ETDEWEB)
Birkenbach, Benedikt; Geibel, Kerstin; Vogt, Andreas; Hess, Herbert; Reiter, Peter; Steinbach, Tim; Schneiders, David [Koeln Univ. (Germany). IKP; Collaboration: AGATA-Collaboration
2013-07-01
Excited states in neutron-rich actinide Th and U nuclei were investigated after multi nucleon transfer reactions employing the AGATA demonstrator and PRISMA setup at LNL (INFN, Italy). A primary {sup 136}Xe beam of 1 GeV hitting a {sup 238}U target was used to produce the nuclei of interest. Beam-like reaction products of Xe- and Ba isotopes after neutron transfer were selected by the PRISMA spectrometer. The recoil like particles were registered by a MCP detector inside the scattering chamber. Coincident γ-rays from excited states in beam and target like particles were measured with the position sensitive AGATA HPGe detectors. Improved Doppler correction and quality of the γ-spectra is based on the novel γ-ray tracking technique which was successfully exploited. First results on the collective properties of various Th and U isotopes are discussed.
Recent topics of mesic atoms and mesic nuclei -- $\\phi$ mesic nuclei exist ?--
Yamagata-Sekihara, J; Cabrera, D; Vacas, M J Vicente
2008-01-01
We study $\\phi$-meson production in nuclei to investigate the in-medium modification of the $\\phi$-meson spectral function at finite density. We consider (${\\bar p},\\phi$), ($\\gamma,p$) and ($\\pi^-,n$) reactions to produce a $\\phi$-meson inside the nucleus and evaluate the effects of the medium modifications to reaction cross sections. The structures of the bound states, $\\phi$-mesic nuclei, are also studied. For strong absorptive interaction cases, we need to know the spectrum shape in a wide energy region to deduce the properties of $\\phi$.
Quasiparticle-phonon interaction in non-magic nuclei
International Nuclear Information System (INIS)
A general microscopic approach to describe properties of excited states in non-magic nuclei is formulated. It is based on the consistent use of the Green function method in Fermi systems with Cooper pairing. The main attention is paid to even-even nuclei, but for odd nuclei with pairing some important relations are obtained too. The quasiparticle-phonon interaction which is introduced acts also in the particle-particle channel and gives a quasiparticle-phonon contribution to pairing. When applied to the theory of giant multipole resonances, the approach includes all known sources of resonance width, i.e. QRPA configurations (which correspond to Landau damping in magic nuclei), the single-particle continuum (escape width) and more complex configurations (spreading width). The use of the Green function method makes it possible to include consistently the ground-state correlations induced by the more complex configurations. In the approximation of the collective phonon creation amplitude squared, which is considered in detail here, these are the ground-state correlations caused by two-quasiparticle-phonon configurations; effects of these correlations have been found earlier to be noticeable for magic nuclei. Such a unified approach will give a reasonable description of the giant resonances' integral characteristics including their widths and of some more delicate properties like fine structure and decay characteristics. Physical arguments and earlier results of a similar approach for magic nuclei allow to use the known parameters of the Landau-Migdal non-separable interaction for all non-magic nuclei (except the light ones). This means that the theory developed is suitable for realistic predictions of the properties of unknown nuclei including unstable ones. The inclusion of the single-particle continuum allows to consider also nuclei with separation energy near zero. (orig.)
Light nuclei production in heavy ion collisions
Khan, K H; Wazir, Z; Khan, E U; Haseeb, Mahnaz Q; Ajaz, M
2009-01-01
Light nuclei production as a result of nuclear coalescence effect can give some signals on final state of Quark Gluon Plasma formation. We are studying the behavior of nuclear modification factor as a function of different variables using the simulated data coming from the FASTMC generator. This data is necessary to extract information on coalescence mechanism from experimental data on high energy nuclear-nuclear interactions.
Nuclear magnetic resonance of thermally oriented nuclei
International Nuclear Information System (INIS)
The more recent developments in the spectroscopy of Nuclear Magnetic Resonance on Oriented Nuclei (NMRON) are reviewed; both theoretical and experimental advances are summarised with applications to On-Line and Off-Line determination of magnetic dipole and electric quadrupole hyperfine parameters. Some emphasis is provided on solid state considerations with indications of where likely enhancements in technique will lead in conventional hyperfine studies. (orig.)
Fayans functional for deformed nuclei. Uranium region
Tolokonnikov, S V; Kortelainen, M; Lutostansky, Yu S; Saperstein, E E
2015-01-01
Fayans energy density functional (EDF) FaNDF^0 has been applied to the nuclei around uranium region. Ground state characteristics of the Th, U and Pu isotopic chains, up to the two-neutron drip line, are found and compared with predictions from several Skyrme EDFs. The two-neutron drip line is found for FaNDF^0, SLy4 and SkM^* EDFs for a set of elements with even proton number, from Pb up to Fm.
Mean Field Studies of Exotic Nuclei}
Chinn, C. R.; Umar, A. S.; Vallières, M.; Strayer, M. R.
1994-01-01
{Full three dimensional static and dynamic mean field calculations using collocation basis splines with a Skyrme type Hamiltonian are described. This program is developed to address the difficult theoretical challenges offered by exotic nuclei. Ground state and deformation properties are calculated using static Hartree-Fock, Hartree-Fock+BCS and constrained Hartree-Fock models. Collective properties, such as reaction rates and resonances, are described using a new alternate method for evaluat...
Structure of residual interaction in spherical nuclei
Kamchatnov, A. M.; Nosov, V. G.
2003-01-01
The effect of residual interaction between nucleons (quasiparticles) on shell oscillations of the masses of spherical nuclei is considered. The singularity of the ground state energy of the system in the vicinity of nucleon magic numbers is analyzed for various types of the dependence of residual interaction on orbital momentum of the quasiparticle. It is shown that only the perturbation band width of the Fermi distribution due to residual interaction which is proportional to the square of th...
Fourth nuclear theory workshop 'clusters in nuclei'
International Nuclear Information System (INIS)
This document gathers the slides of 3 lectures: 1) the R-matrix method, 2) from realistic NN-interactions to cluster structures in nuclei - in this part the unitary correlation operator method (UCOM) is applied to 3 domains: the fermionic molecular dynamics, the Hartree-Fock approximation, and the no-core shell model -, and 3) the shell model point of view on cluster states
Electromagnetic properties of nuclei at high spins
International Nuclear Information System (INIS)
A photon emitted by an excited state is likely to carry away, at most, 1 or 2 h-bar of angular momentum. Therefore, a profusion of photons is needed to deexcite the rapidly rotating states of nuclei formed by heavy-ion reactions. The study of electromagnetic properties has become the primary source of information on nuclear structure at high spins and, also, at the warm temperatures present in the initial stage of the electromagnetic cascade process. The purpose of this paper is a review of the E1, M1, and E2 properties of such highly excited states. 42 refs., 5 figs
International Nuclear Information System (INIS)
We study nuclear potential-energy surfaces, ground-state masses and shapes calculated by use of a Yukawa-plus-exponential macroscopic model and a folded-Yukawa single-particle potential for 4023 nuclei ranging from 16O to 279112. We discuss extensively the transition from spherical to deformed shapes and study the relation between shape changes and the mass corresponding to the ground-state minimum. The calculated values for the ground-state mass and shape show good agreement with experimental data throughout the periodic system, but some discrepancies remain that deserve further study. We also discuss the effect of deformation on Gamow-Teller #betta#-strength functions
Ayala, A P; Levin, E M
1996-01-01
In this talk we present our detail study ( theory and numbers) [1] on the shadowing corrections to the gluon structure functions for nuclei. Starting from rather contraversial information on the nucleon structure function which is originated by the recent HERA data, we develop the Glauber approach for the gluon density in a nucleus based on Mueller formula [2] and estimate the value of the shadowing corrections in this case. Than we calculate the first corrections to the Glauber approach and show that these corrections are big. Based on this practical observation we suggest the new evolution equation which takes into account the shadowing corrections and solve it. We hope to convince you that the new evolution equation gives a good theoretical tool to treat the shadowing corrections for the gluons density in a nucleus and, therefore, it is able to provide the theoretically reliable initial conditions for the time evolution of the nucleus - nucleus cascade.
International Nuclear Information System (INIS)
The present collection of letters from JINR, Dubna, contains nine separate records on the transport of the evanescent electron beam in the vacuum section with plasma disks, determination of ΔΓs from analysis of untagged decays Bs0→J/ψφ by using the method of angular moments, investigation of light nucleus clustering in relativistic multifragmentation processes, secondary fragments of relativistic 22Ne at 4.1 A · GeV/c nuclei in nuclear emulsion, extrapolation of experimental data of accelerated radiation aging to the operation condition of dipole magnet electrical insulation at low dose rates, automatic quality control system of the installed straws into TRT wheels, a new method of fast simulation for a hadron calorimeter response, empirical evidence for relation between threshold effects and neutron strength function as well as on what information can be derived when no events are registered
Xu, Renxin
2011-01-01
What is the real nature of pulsars? This is essentially a question of the fundamental strong interaction between quarks at low-energy scale and hence of the non-perturbative quantum chromo-dynamics, the solution of which would certainly be meaningful for us to understand one of the seven millennium prize problems (i.e., "Yang-Mills Theory") named by the Clay Mathematical Institute. After a historical note, it is argued here that a pulsar is very similar to an extremely big nucleus, but is a little bit different from the {\\em gigantic nucleus} speculated 80 years ago by L. Landau. The paper demonstrates the similarity between pulsars and gigantic nuclei from both points of view: the different manifestations of compact stars and the general behavior of the strong interaction.
Beck, Christian
Following the pioneering discovery of alpha clustering and of molecular resonances, the field of nuclear clustering is today one of those domains of heavy-ion nuclear physics that faces the greatest challenges, yet also contains the greatest opportunities. After many summer schools and workshops, in particular over the last decade, the community of nuclear molecular physicists has decided to collaborate in producing a comprehensive collection of lectures and tutorial reviews covering the field. This third volume follows the successful Lect. Notes Phys. 818 (Vol. 1) and 848 (Vol. 2), and comprises six extensive lectures covering the following topics: - Gamma Rays and Molecular Structure - Faddeev Equation Approach for Three Cluster Nuclear Reactions - Tomography of the Cluster Structure of Light Nuclei Via Relativistic Dissociation - Clustering Effects Within the Dinuclear Model : From Light to Hyper-heavy Molecules in Dynamical Mean-field Approach - Clusterization in Ternary Fission - Clusters in Light N...
Beck, C; Zafra, A Sanchez i; Thummerer, S; Azaiez, F; Bednarczyk, P; Courtin, S; Curien, D; Dorvaux, O; Goasduff, A; ~Lebhertz, D; Nourreddine, A; ~Rousseau, M; Salsac, M -D; von Oertzen, W; Gebauer, B; Wheldon, C; Kokalova, Tz; Efimov, G; Zherebchevsky, V; Schulz, Ch; Bohlen, H G; Kamanin, D; de Angelis, G; Gadea, A; Lenzi, S; Napoli, D R; Szilner, S; Milin, M; Catford, W N; Jenkins, D G; Royer, G
2010-01-01
A great deal of research work has been undertaken in the alpha-clustering study since the pioneering discovery, half a century ago, of 12C+12C molecular resonances. Our knowledge of the field of 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 alpha-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.
Cavitation inception from bubble nuclei
DEFF Research Database (Denmark)
Mørch, Knud Aage
2015-01-01
The tensile strength of ordinary water such as tap water or seawater is typically well below 1 bar. It is governed by cavitation nuclei in the water, not by the tensile strength of the water itself, which is extremely high. Different models of the nuclei have been suggested over the years......, and experimental investigations of bubbles and cavitation inception have been presented. These results suggest that cavitation nuclei in equilibrium are gaseous voids in the water, stabilized by a skin which allows diffusion balance between gas inside the void and gas in solution in the surrounding liquid....... The cavitation nuclei may be free gas bubbles in the bulk of water, or interfacial gaseous voids located on the surface of particles in the water, or on bounding walls. The tensile strength of these nuclei depends not only on the water quality but also on the pressure-time history of the water. A recent model...
Directory of Open Access Journals (Sweden)
Holt Roy J.
2016-01-01
Full Text Available Electron scattering at very high Bjorken x from hadrons provides an excellent test of models, has an important role in high energy physics, and from nuclei, provides a window into short range correlations. Light nuclei have a key role because of the relatively well-known nuclear structure. The development of a novel tritium target for Jefferson Lab has led to renewed interest in the mass three system. For example, deep inelastic scattering experiments in the light nuclei provide a powerful means to determine the neutron structure function. The isospin dependence of electron scattering from mass-3 nuclei provide information on short range correlations in nuclei. The program using the new tritium target will be presented along with a summary of other experiments aimed at revealing the large-x structure of the nucleon.
2007-01-01
The evolution of the unknown ground-state ${\\beta}$-decay properties of the neutron-rich $^{84-89}$Ge, $^{90-93}$Se and $^{102-104}$Sr isotopes near the r-process path is of high interest for the study of the abundance peaks around the N=50 and N=82 neutron shells. At ISOLDE, beams of certain elements with sufficient isotopic purity are produced as molecular sidebands rather than atomic beams. This applies e.g, to germanium, separated as GeS$^{+}$, selenium separated as SeCO$^{+}$ and strontium separated as SrF$^{+}$. However, in case of neutron-rich isotopes produced in actinide targets, new "isobaric" background of atomic ions appears on the mass of the molecular sideband. For this particular case, the ECR charge breeder, positioned in the experimental hall after ISOLDE first mass separation, can be advantageously used as a purification device, by breaking the molecules and removing the molecular contaminants. This proposal indicates our interest in the study of basic nuclear structure properties of neutron...
Guardiola, R; Navarro, J; Bishop, R F; Puente, A; Walet, N R; Walet, Niels R.
1996-01-01
We study the extension of our translationally invariant treatment of few-body nuclear systems to heavier nuclei. At the same time we also introduce state-dependent correlation operators. Our techniques are tailored to those nuclei that can be dealt with in $LS$ coupling, which includes all nuclei up to the shell closure at $A=40$. We study mainly $p$-shell nuclei in this paper. A detailed comparison with other microscopic many-body approaches is made, using a variety of schematic nuclear interactions. It is shown that our methodology produces very good energies, and presumably also wave functions, for medium mass nuclei.
Quadrupole moments of odd-odd near-magic nuclei
Achakovskiy O.; Voitenkov D.; Kamerdzhiev S.; Tolokonnikov S.
2012-01-01
Ground state quadrupole moments of odd-odd near double magic nuclei are calculated in the approximation of no interaction between odd particles. Under such a simple approximation, the problem is reduced to the calculations of quadrupole moments of corresponding odd-even nuclei. These calculations are performed within the self-consistent Theory of Finite Fermi Systems based on the Energy Density Functional by Fayans et al. with the known DF3-a parameters. A reasonable agreement with the availa...
Interaction of eta mesons with nuclei
Kelkar, N G; Upadhyay, N J; Jain, B K
2013-01-01
Back in the mid eighties, a new branch of investigation which was related to the interaction of eta mesons with nuclei came into existence. It started with the theoretical prediction of possible exotic states of eta mesons and nuclei bound by the strong interaction and later developed into an extensive experimental program to search for such unstable states as well as understand the underlying interaction via eta meson producing reactions. The vast literature of experimental as well as theoretical works which studied various aspects of eta producing reactions such as the $\\pi ^+$ $n$ $\\to \\eta p$, $p d \\to ^3$He $\\eta$, $p \\,^6$Li $\\to ^7$Be $\\eta$ and $\\gamma ^3$He $\\to \\eta$ X, to name a few, had but one objective in mind: to understand the eta - nucleon ($\\eta N$) and hence the $\\eta$-nucleus interaction which could explain the production data and confirm the existence of some $\\eta$-mesic nuclei. In spite of these efforts, there remain uncertainties in the knowledge of the $\\eta N$ and hence the $\\eta$-nu...
3rd International conference on nuclei far from stability, Cargese, Corsica, 19-26 May 1976
International Nuclear Information System (INIS)
These conference proceedings contain 103 contributions which are grouped under the following headings: Experimental methods and techniques; Perspectives in research on exotic nuclei; Nuclear masses - experiment and theory; Nuclear spins, moments, and radii; Light nuclei; Delayed particle emission and statistical aspects; Excited states of neutron-deficient nuclei; Excited states of fission products and other neutron-rich isotopes; Heavy elements and astrophysical aspects. Also included are the Scientific programme and a List of participants. (AJ)
Antiproton Induced Fission and Fragmentation of Nuclei
2002-01-01
The annihilation of slow antiprotons with nuclei results in a large highly localized energy deposition primarily on the nuclear surface. \\\\ \\\\ The study of antiproton induced fission and fragmentation processes is expected to yield new information on special nuclear matter states, unexplored fission modes, multifragmentation of nuclei, and intranuclear cascades.\\\\ \\\\ In order to investigate the antiproton-nucleus interaction and the processes following the antiproton annihilation at the nucleus, we propose the following experiments: \\item A)~Measurement of several fragments from fission and from multifragmentation in coincidence with particle spectra, especially neutrons and kaons. \\item B)~Precise spectra of $\\pi$, K, n, p, d and t with time-of-flight techniques. \\item C)~Installation of the Berlin 4$\\pi$ neutron detector with a 4$\\pi$ Si detector placed inside for fragments and charged particles. This yields neutron multiplicity distributions and consequently distributions of thermal excitation energies and...
Effective Field Theory for Lattice Nuclei
Barnea, N.; Contessi, L.; Gazit, D.; Pederiva, F.; van Kolck, U.
2015-02-01
We show how nuclear effective field theory (EFT) and ab initio nuclear-structure methods can turn input from lattice quantum chromodynamics (LQCD) into predictions for the properties of nuclei. We argue that pionless EFT is the appropriate theory to describe the light nuclei obtained in LQCD simulations carried out at pion masses heavier than the physical pion mass. We solve the EFT using the effective-interaction hyperspherical harmonics and auxiliary-field diffusion Monte Carlo methods. Fitting the three leading-order EFT parameters to the deuteron, dineutron, and triton LQCD energies at mπ≈800 MeV , we reproduce the corresponding alpha-particle binding and predict the binding energies of mass-5 and mass-6 ground states.
Effective Field Theory for Lattice Nuclei
Barnea, N; Gazit, D; Pederiva, F; van Kolck, U
2013-01-01
We show how nuclear effective field theory (EFT) and ab initio nuclear-structure methods can turn input from lattice quantum chromodynamics (LQCD) into predictions for the properties of nuclei. We argue that pionless EFT is the appropriate theory to describe the light nuclei obtained in recent LQCD simulations carried out at pion masses much heavier than the physical pion mass. We solve the EFT using the effective-interaction hyperspherical harmonics and auxiliary-field diffusion Monte Carlo methods. Fitting the three leading-order EFT parameters to the deuteron, dineutron and triton LQCD energies at $m_{\\pi}\\approx 800$ MeV, we reproduce the corresponding alpha-particle binding and predict the binding energies of mass-5 and 6 ground states.
Collective properties of drip-line nuclei
Energy Technology Data Exchange (ETDEWEB)
Hamamoto, I. [Univ. of Lund (Sweden); Sagawa, H. [Univ. of Aizu, Fukushima (Japan)
1996-12-31
Performing the spherical Hartree-Fock (HF) calculations with Skyrme interactions and, then, using RPA solved in the coordinate space with the Green`s function method, the authors have studied the effect of the unique shell structure as well as the very low particle threshold on collective modes in drip line nuclei. In this method a proper strength function in the continuum is obtained, though the spreading width of collective modes is not included. They have examined also one-particle resonant states in the obtained HF potential. Unperturbed particle-hole (p-h) response functions are carefully studied, which contain all basic information on the exotic behaviour of the RPA strength function in drip line nuclei.
Isospin Mixing In N $\\approx$ Z Nuclei
Srnka, D; Versyck, S; Zakoucky, D
2002-01-01
Isospin mixing in N $\\approx$ Z nuclei region of the nuclear chart is an important phenomenon in nuclear physics which has recently gained theoretical and experimental interest. It also forms an important nuclear physics correction in the precise determination of the $ft$-values of superallowed 0$^+ \\rightarrow 0^+ \\beta$- transitions. The latter are used in precision tests of the weak interaction from nuclear $\\beta$- decay. We propose to experimentally measure isospin mixing into nuclear ground states in the N $\\approx$ Z region by determining the isospin forbidden Fermi-component in the Gamow-Teller dominated $J^{\\pi} \\rightarrow J^{\\pi} \\beta$- transitions through the observation of anisotropic positron emission from oriented nuclei. First measurements were carried out with $^{71}$As and are being analyzed now.
Nuclear structure investigations on spherical nuclei
International Nuclear Information System (INIS)
This report discusses the following topics: electron scattering studies on spherical nuclei; electron scattering from collective states in deformed nuclei; proton and pion scattering studies; 12C(e,e'p) and 16O(e,e'p); 12C(e,e'α) and 16O(e,e'α); studies at high q at Bates; measurements with rvec e at Bates; 12C(γ,p); future directions in giant resonance studies; proton knockout from 16O; quasielastic studies at Bates; triple coincidence studies of nuclear correlations; contributions to (e,e'2p) at KIKHEF; contributions to instrumentation at CEBAF; instrumentation development at UNH; the Bates large acceptance spectrometer toroid; shell model and core polarization calculations; and the relativistic nuclear model
Mishustin, I N; Buervenich, T J; Stöcker, H; Greiner, W
2005-01-01
We study the possibility of producing a new kind of nuclear systems which in addition to ordinary nucleons contain a few antibaryons (antiproton, antilambda, etc.). The properties of such systems are described within the relativistic mean-field model by employing G-parity transformed interactions for antibaryons. Calculations are first done for infinite systems and then for finite nuclei from He to Pb. It is demonstrated that the presence of a real antibaryon leads to a strong rearrangement of a target nucleus resulting in a significant increase of its binding energy and local compression. Noticeable effects remain even after the antibaryon coupling constants are reduced by factor 3-4 compared to G-parity motivated values. We have performed detailed calculations of the antibaryon annihilation rates in the nuclear environment by applying a kinetic approach. It is shown that due to significant reduction of the reaction Q-values, the in-medium annihilation rates should be strongly suppressed leading to relativel...
Spectroscopy of heavy fissionable nuclei
Indian Academy of Sciences (India)
S K Tandel
2015-09-01
Structural studies of heavy nuclei are quite challenging due to increased competition from fission, particularly at high spins. Nuclei in the actinide region exhibit a variety of interesting phenomena. Recent advances in instrumentation and analysis techniques have made feasible sensitive measurements of nuclei populated with quite low cross-sections. These include isomers and rotational band structures in isotopes of Pu ( = 94) to Rf ( = 104), and octupole correlations in the Th ( = 90) region. The obtained experimental data have provided insights on various aspects like moments of inertia and nucleon alignments at high spins, quasiparticle energies and evolution of quadrupole and octupole collectivity, among others. An overview of some of these results is presented.
Deformed $sd$-shell nuclei from first principles
Jansen, G R; Hagen, G; Navrátil, P
2015-01-01
We extend the ab initio coupled-cluster effective interaction (CCEI) method to deformed open-shell nuclei with protons and neutrons in the valence space, and compute binding energies and excited states of isotopes of neon and magnesium. We employ a nucleon-nucleon and three-nucleon interaction from chiral effective field theory evolved to a lower cutoff via a similarity renormalization group transformation. We find good agreement with experiment for binding energies and spectra, while charge radii of neon isotopes are underestimated. For the deformed nuclei $^{20}$Ne and $^{24}$Mg we reproduce rotational bands and electric quadrupole transitions within uncertainties estimated from an effective field theory for deformed nuclei, thereby demonstrating that collective phenomena in $sd$-shell nuclei emerge from complex ab initio calculations.
Scissors mode of Gd nuclei studied from resonance neutron capture
Kroll, J.; Baramsai, B.; Becker, J. A.; Bečvár, F.; Bredeweg, T. A.; Couture, A.; Chyzh, A.; Dashdorj, D.; Haight, R. C.; Heil, M.; Jandel, M.; Käppeler, F.; Krtička, M.; Mitchell, G. E.; O'Donnell, J. M.; Parker, W.; Reifarth, R.; Rundberg, R. S.; Ullmann, J. L.; Valenta, S.; Vieira, D. J.; Walker, C. L.; Wilhelmy, J. B.; Wouters, J. M.; Wu, C. Y.
2012-10-01
Spectra of γ rays following the neutron capture at isolated resonances of stable Gd nuclei weremeasured. The objectives were to get new information on photon strength of 153,155-159Gd with emphasis on the role of the M1 scissors-mode vibration. An analysis of the data obtained clearly indicates that the scissors mode is coupled not only to the ground state, but also to all excited levels of the nuclei studied. The specificity of our approach ensures unbiasedness in estimating the sumed scissors-mode strength ΣB(M1)↑, even for odd product nuclei, for which conventional nuclear resonance fluorescence measurements yield only limited information. Our analysis indicates that for these nuclei the sum ΣB(M1)↑ increases with A and for 157,159Gd it is significantly higher compared to 156,158Gd.
Magnetic moments of odd-odd spherical nuclei
Achakovskiy, O I; Saperstein, E E; Tolokonnikov, S V
2013-01-01
Magnetic moments of more than one hundred odd-odd spherical nuclei in ground and excited states are calculated within the self-consistent TFFS based on the EDF method by Fayans {\\it et al}. We limit ourselves to nuclei with a neutron and a proton particle (hole) added to the magic or semimagic core. A simple model of no interaction between the odd nucleons is used. In most the cases we analyzed, a good agreement with the experimental data is obtained. Several cases are considered where this simple model does not work and it is necessary to go beyond. The unknown values of magnetic moments of many unstable odd and odd-odd nuclei are predicted including sixty values for excited odd-odd nuclei.
Photoproduction of Pseudoscalar Mesons off Nuclei at Forward Angles
Gevorkyan, S; Gan, L; Larin, I; Khandaker, M
2009-01-01
With the advent of new photon tagging facilities and novel experimental technologies it has become possible to perform photoproduction cross section measurements of pseudoscalar mesons on nuclei with a percent level accuracy. The extraction of the radiative decay widths from these measurements at forward angles is done by the Primakoff method, which requires theoretical treatment of all processes participating in these reactions at the same percent level. In this work we review the theoretical approach to meson photoproduction amplitudes in the electromagnetic and strong fields of nuclei at forward direction. The most updated description of these processes are presented based on the Glauber theory of multiple scattering. In particular, the effects of final state interactions, corrections for light nuclei, and photon shadowing in nuclei are discussed.
Pseudospin Dynamical Symetry in Nuclei
Ginocchio, Joseph N
2014-01-01
Pseudospin symmetry has been useful in understanding atomic nuclei. We review the arguments that this symmetry is a relativistic symmetry. The condition for this symmetry is that the sum of the vector and scalar potentials in the Dirac Hamiltonian is a constant. We give the generators of pseudospin symmetry. We review some of the predictions that follow from this insight into the relativistic origins of pseudospin symmetry. Since in nuclei the sum of the scalar and vector potentials is not zero but is small, we discuss preliminary investigations into the conditions on the potentials to produce partial dynamic pseudospin symmetry. Finally we show that approximate pseudospin symmetry in nuclei predicts approximate spin symmetry in anti-nucleon scattering from nuclei.
Physics with loosely bound nuclei
Indian Academy of Sciences (India)
Chhanda Samanta
2001-08-01
The essential aspect of contemporary physics is to understand properties of nucleonic matter that constitutes the world around us. Over the years research in nuclear physics has provided strong guidance in understanding the basic principles of nuclear interactions. But, the scenario of nuclear physics changed drastically as the new generation of accelerators started providing more and more rare isotopes, which are away from the line of stability. These weakly bound nuclei are found to exhibit new forms of nuclear matter and unprecedented exotic behaviour. The low breakup thresholds of these rare nuclei are posing new challenges to both theory and experiments. Fortunately, nature has provided a few loosely bound stable nuclei that have been studied thoroughly for decades. Attempts are being made to ﬁnd a consistent picture for the unstable nuclei starting from their stable counterparts. Some signiﬁcant differences in the structure and reaction mechanisms are found.
International Nuclear Information System (INIS)
PANIC is the triennal International Conference on Particles and Nuclei, and judging from the latest PANIC, held in Kyoto from 20-24 April there is no need for panic yet. Faced with two pictures – one of nuclei described in nucleon and meson terms, and another of nucleons containing quarks and gluons – physicists are intrigued to know what new insights from the quark level can tell us about nuclear physics, or vice versa
Adiabatic fission barriers in superheavy nuclei
Jachimowicz, P; Skalski, J
2016-01-01
Using the microscopic-macroscopic model based on the deformed Woods-Saxon single-particle potential and the Yukawa-plus-exponential macroscopic energy we calculated static fission barriers $B_{f}$ for 1305 heavy and superheavy nuclei $98\\leq Z \\leq 126$, including even - even, odd - even, even - odd and odd - odd systems. For odd and odd-odd nuclei, adiabatic potential energy surfaces were calculated by a minimization over configurations with one blocked neutron or/and proton on a level from the 10-th below to the 10-th above the Fermi level. The parameters of the model that have been fixed previously by a fit to masses of even-even heavy nuclei were kept unchanged. A search for saddle points has been performed by the "Imaginary Water Flow" method on a basic five-dimensional deformation grid, including triaxiality. Two auxiliary grids were used for checking the effects of the mass asymmetry and hexadecapole non-axiallity. The ground states were found by energy minimization over configurations and deformations...
Fusion excitation functions involving transitional nuclei
Energy Technology Data Exchange (ETDEWEB)
Rehm, K.E.; Jiang, C.L.; Esbensen, H. [and others
1995-08-01
Measurements of fusion excitation functions involving transitional nuclei {sup 78}Kr and {sup 100}Mo showed a different behavior at low energies, if compared to measurements with {sup 86}Kr and {sup 92}Mo. This points to a possible influence of nuclear structure on the fusion process. One way to characterize the structure of vibrational nuclei is via their restoring force parameters C{sub 2} which can be calculated from the energy of the lowest 2{sup +} state and the corresponding B(E2) value. A survey of the even-even nuclei between A = 28-150 shows strong variations in C{sub 2} values spanning two orders of magnitude. The lowest values for C{sub 2} are observed for {sup 78}Kr, {sup 104}Ru and {sup 124}Xe followed by {sup 74,76}Ge, {sup 74,76}Se, {sup 100}Mo and {sup 110}Pd. In order to learn more about the influence of {open_quotes}softness{close_quotes} on the sub-barrier fusion enhancement, we measured cross sections for evaporation residue production for the systems {sup 78}Kr + {sup 104}Ru and {sup 78}Kr + {sup 76}Ge with the gas-filled magnet technique. For both systems, fusion excitation functions involving the closed neutron shell nucleus {sup 86}Kr were measured previously. The data are presently being analyzed.
Symmetry remnants in the face of competing interactions in nuclei
Energy Technology Data Exchange (ETDEWEB)
Leviatan, A., E-mail: ami@phys.huji.ac.il [Racah Institute of Physics, The Hebrew University, Jerusalem 91904 (Israel); Macek, M., E-mail: michal.macek@yale.edu [Center for Theoretical Physics, Sloane Physics Laboratory, Yale University, New Haven, CT 06520-8120 (United States)
2015-10-15
Detailed description of nuclei necessitates model Hamiltonians which break most dynamical symmetries. Nevertheless, generalized notions of partial and quasi dynamical symmetries may still be applicable to selected subsets of states, amidst a complicated environment of other states. We examine such scenarios in the context of nuclear shape-phase transitions.
Symmetry Remnants in the Face of Competing Interactions in Nuclei
Leviatan, A
2015-01-01
Detailed description of nuclei necessitates model Hamiltonians which break most dynamical symmetries. Nevertheless, generalized notions of partial and quasi dynamical symmetries may still be applicable to selected subsets of states, amidst a complicated environment of other states. We examine such scenarios in the context of nuclear shape-phase transitions.
Effect of properties of superheavy nuclei on their production and decay
Adamian, G. G.; Antonenko, N. V.; Bezbakh, A. N.; Jolos, R. V.
2016-05-01
Properties and stability of superheavy nuclei resulting from hot fusion are discussed. It is shown that the microscopic-macroscopic approach allows obtaining the closed proton shell at Z ≥ 120. Isotopic trends of K-isomeric states in superheavy nuclei are predicted. Evaporation residue cross sections in hot fusion reactions are calculated using the predicted properties of superheavy nuclei. Interruption of α decay chains by spontaneous fission is analyzed. Alpha decay chains through isomeric states are considered. Internal level densities in superheavy nuclei are microscopically calculated.
Spectrin-like proteins in plant nuclei
Ruijter, de N.C.A.; Ketelaar, T.; Blumenthal, S.S.D.; Emons, A.M.C.; Schel, J.H.N.
2000-01-01
We analysed the presence and localization of spectrin-like proteins in nuclei of various plant tissues, using several anti-erythrocyte spectrin antibodies on isolated pea nuclei and nuclei in cells. Western blots of extracted purified pea nuclei show a cross-reactive pair of bands at 220–240 kDa, ty
Cluster formation, breaking, and excitation in light nuclei
International Nuclear Information System (INIS)
In this paper, we discuss cluster phenomena in light nuclei based on calculations using the antisymmetrized molecular dynamics (AMD) method. Cluster structures in C, B, and Be were studied systematically, and their cluster formation and excitation are discussed. Cluster gas states and their band members are suggested for the excited states of 12C and 11B. The ground state cluster correlation and excited cluster gas state are discussed from the point of view of symmetry breaking and restoration. (authors)
From heavy nuclei to super-heavy nuclei
International Nuclear Information System (INIS)
The existence of super-heavy nuclei has been predicted nearly fifty years ago. Due to the strong coulomb repulsion, the stabilisation of these nuclei is possible only through shell effects. The reasons for this fragile stability, as well as the theoretical predictions concerning the position of the island of stability are presented in the first part of this lecture. In the second part, experiments and experimental techniques which have been used to synthesize or search for super-heavy elements are described. Spectroscopic studies performed in very heavy elements are presented in the following section. We close this lecture with techniques that are currently being developed in order to reach the superheavy island and to study the structure of very-heavy nuclei. (author)
Double-beta decay in deformed nuclei
International Nuclear Information System (INIS)
A brief review of theoretical results for the double-beta decay and the double-electron capture in heavy deformed nuclei is presented. The ββ half life of 160Gd is evaluated using an extended version of the pseudo SU(3) model. While the 2ν mode is forbidden when the most probable occupations are considered, states with different occupation numbers can be mixed through the pairing interaction. The amount of this mixing is calculated using perturbation theory. The possibility of observing the ββ decay in 160Gd is discussed for both the 2ν and 0ν modes. (author)
Isovector excitations of N ≠ Z nuclei
International Nuclear Information System (INIS)
We show that the method based on the tensor coupling of an appropriate family of isovector excitation operators to the parent isospin multiplet can be used, to advantage, for the correct treatment of the isospin degree of freedom in non isoscalar nuclei. This method is applicable to any isovector excitation operator and for parent states which need not to be of the closed subshells type. As an illustration we apply it to the study of the Gamow-Teller transition strength in 90Zr. (author)
Selected topics on Hadrons in Nuclei
Oset, E; Hernandez, E; Ramos, A; Magas, V K; Yamagata-Sekihara, J; Hirenzaki, S; Gamermann, D; Molina, R; Tolos, L; Roca, L
2011-01-01
In this talk we report on selected topics on hadrons in nuclei. The first topic is the renormalization of the width of the $\\Lambda(1520)$ in a nuclear medium. This is followed by a short update of the situation of the $\\omega$ in the medium. The investigation of the properties of $\\bar{K}$ in the nuclear medium from the study of the $(K_{flight},p)$ reaction is also addressed, as well as properties of X,Y,Z charmed and hidden charm resonances in a nuclear medium. Finally we address the novel issue of multimeson states.
Inclusive inelastic electron scattering from nuclei
Fomin, Nadia
2007-01-01
Inclusive electron scattering from nuclei at large x and $Q^2$ is the result of a reaction mechanism that includes both quasi--elastic scattering from nucleons and deep inelastic scattering from the quark constituents of the nucleons. Data in this regime can be used to study a wide variety of topics, including the extraction of nuclear momentum distributions, the influence of final state interactions and the approach to $y$-scaling, the strength of nucleon-nucleon correlations, and the approach to $x$- scaling, to name a few. Selected results from the recent experiment E02-019 at the Thomas Jefferson National Accelerator Facility will be shown and their relevance discussed.
Signature Inversion in Odd-odd Nuclei
Institute of Scientific and Technical Information of China (English)
LIU Min-liang; ZHANG Yu-hu; ZHOU Xiao-hong; GUO Ying-xiang; LEI Xiang-guo; GUO Wen-tao
2009-01-01
Signature inversion in odd-odd nuclei is investigated by using a proton and a neutron coupling to the coherent state of the core.Two parameters are employed in the Hamiltonian to set the energy scales of rotation,neutron-proton coupling and their competition.Typical level staggering is extracted from the calculated level energies.The calculation can approximately reproduce experimental signature inversion.Signature inversion is attributed to the rotational motion and neutronproton residual interaction having reversed signature splitting rules.It is found signature inversion can appear at axially symmetric shape and high-K band.
A quasi-particle model for computational nuclei
International Nuclear Information System (INIS)
A model Hamiltonian is derived which provides a computationally efficient means of representing nuclei. The Hamiltonian includes both coulomb and isospin dependent terms, and incorporates antisymmetrization effects through a momentum dependent potential. Unlike many other classical or semiclassical models, the nuclei of this simulation have a well-defined ground state with a a non-vanishing 2>. It is shown that the binding energies per nucleon and r.m.s. radii of these ground states are close to the measured values over a wide mass range
Modification of meson properties in the vicinty of nuclei
Directory of Open Access Journals (Sweden)
Filip Peter
2014-01-01
Full Text Available We suggest that modification of meson properties (lifetimes and branching ratios can occur due to the interaction of constituent quark magnetic moments with strong magnetic fields present in the close vicinity of nuclei. A superposition of (J =0 and (J =1, mz =0 particle-antiparticle quantum states (as observed for ortho-Positronium may occur also in the case of quarkonium states J/Ψ, ηc ϒ, ηb in heavy ion collisions. We speculate on possible modification of η(548 meson properties (related to C parity and CP violation in strong magnetic fields which are present in the vicinity of nuclei.
{Delta}I = 2 energy staggering in normal deformed dysprosium nuclei
Energy Technology Data Exchange (ETDEWEB)
Riley, M.A.; Brown, T.B.; Archer, D.E. [Florida State Univ., Tallahassee, FL (United States)] [and others
1996-12-31
Very high spin states (I{ge}50{Dirac_h}) have been observed in {sup 155,156,157}Dy. The long regular band sequences, free from sharp backbending effects, observed in these dysprosium nuclei offer the possibility of investigating the occurence of any {Delta}I = 2 staggering in normal deformed nuclei. Employing the same analysis techniques as used in superdeformed nuclei, certain bands do indeed demonstrate an apparent staggering and this is discussed.
Cavitation inception from bubble nuclei.
Mørch, K A
2015-10-01
The tensile strength of ordinary water such as tap water or seawater is typically well below 1 bar. It is governed by cavitation nuclei in the water, not by the tensile strength of the water itself, which is extremely high. Different models of the nuclei have been suggested over the years, and experimental investigations of bubbles and cavitation inception have been presented. These results suggest that cavitation nuclei in equilibrium are gaseous voids in the water, stabilized by a skin which allows diffusion balance between gas inside the void and gas in solution in the surrounding liquid. The cavitation nuclei may be free gas bubbles in the bulk of water, or interfacial gaseous voids located on the surface of particles in the water, or on bounding walls. The tensile strength of these nuclei depends not only on the water quality but also on the pressure-time history of the water. A recent model and associated experiments throw new light on the effects of transient pressures on the tensile strength of water, which may be notably reduced or increased by such pressure changes. PMID:26442138
Statistical properties of quantum spectra in nuclei
Institute of Scientific and Technical Information of China (English)
WU; Xizhen
2001-01-01
［1］Wu Xizhen,Sakata,F.,Zhuo Yizhong et al.,Dynamic realization of statistical state in finite systems,Phys.ReV.C,1996,53:1233-1244.［2］Weidenmüller,H.A.,Statistical theory of nuclear reactions and the Gaussian Othogonal Ensemble,Annals of Physics,1984,158:120-141.［3］Hag,R.U.,Pandey,A.,Bohigas,O.,Fluctuation properties of nuclear energy levels:Do theory and experiment agree? Phys.Rev.Lett.,1982,48:1086-1089.［4］Wu Xizhen,Gu Jianzhong,Iwamoto,A.,Statistical properties of quasiparticle spectra in deformed nuclei,Phys.Rev.C,1999,59:215-220.［5］Garrett,J.D.,Robinson,J.Q.,Foglia,A.J.et al.,Nuclear level repulsion and order vs chaos,Phys.Lett.B,1997,392:24-29.［6］Bohigas,O.,Hag,R.U.,Pandy,A.,Fluctuation properties of nuclear energy levels and widths comparison of theory with experiment,in Nuclear Data for Science and Technology (ed.Bockhoff,K.H.),Dordrecht:Reidel,1983,809-813.［7］Heiss,W.D.,Nazmitdinov,R.G.,Radu,S.,Chaos in axially symmetric potentials with Octupole deformation,Phys.Rev.Lett.,1994,72:2351-2354.［8］Wu Xizhen,Gu Jianzhong,Zhuo Yizhong et al.,Possible understanding of hyperdeformed 144-146Ba nuclei appearing in the spontaneous fission of 252Cf,Phys.Rev.Lett.,1997,79:4542-4545.［9］Ter-Akopian,G.M.,Hamilton,J.H.,Oganessian,Y.T.et al.,New spontaneous fission mode for 252Cf:Indication of hyperdeformed 144,145,146Ba at scission,Phys.Rev.Lett.,1996,77:32-35.［10］Adamian,G.G.,Antonenko,N.V.,Ivanova,S.P.et al.,Problems in description of fusion of heavy nuclei in the two-center shell model approach,Nucl.Phys.A,1999,646:29-52.［11］Hofmann,H.,A quantal transport theory for nuclear collective motion:the metrits of a locally harmonic approximation method,Phys.Rep.,1997,284:139-380.［12］Gu Jianzhong,Wu Xizhen,Zhuo Yizhong,Quantum chaotic motion of a single particle in heavy nuclei,Nucl.Phys.A,1997,625:621-632.［13］Gu Jianzhong,Wu Xizhen,Zhuo Yizhong,The single-particle spectrum and its spacing and curvature distributions in
Clusters in neutron-rich light nuclei
Directory of Open Access Journals (Sweden)
Jelavić Malenica D.
2016-01-01
Full Text Available Due to their high selectivity, transfer and sequential decay reactions are powerful tools for studies of both single particle (nucleon and cluster states in light nuclei. Their use is particularly simple for investigations of α-particle clustering (because α-particle has Jπ=0+, which simplifies spin and parity assignments to observed cluster states, but they are also easily applicable to other types of clustering. Recent results on clustering in neutron-rich isotopes of beryllium, boron and carbon obtained measuring the 10B+10B reactions (at 50 and 72 MeV are presented. The highly efficient and segmented detector systems used, built from 4 Double Sided Silicon Strip Detectors (DSSSD allowed detection of double and multiple coincidences and, in that way, studies of states populated in transfer reactions, as well as their sequential decay.
Skyrme RPA for spherical and axially symmetric nuclei
Repko, Anton; Nesterenko, V O; Reinhard, P -G
2015-01-01
Random Phase Approximation (RPA) is the basic method for calculation of excited states of nuclei over the Hartree-Fock ground state, suitable also for energy density functionals (EDF or DFT). We developed a convenient formalism for expressing densities and currents in a form of reduced matrix elements, which allows fast calculation of spectra for spherical nuclei. All terms of Skyrme functional were taken into account, so it is possible to calculate electric, magnetic and vortical/toroidal/compression transitions and strength functions of any multipolarity. Time-odd (spin) terms in Skyrme functional become important for magnetic M1 and isovector toroidal E1 transitions. It was also found that transition currents in pygmy region (low-lying part of E1 resonance) exhibit isoscalar toroidal flow, so the previously assumed picture of neutron-skin vibration is not the only mechanism present in pygmy transitions. RPA calculations with heavy axially-symmetric nuclei now become feasible on ordinary PC. Detailed formul...
International Symposium on Exotic Nuclei
Sobolev, Yu G; EXON-2014
2015-01-01
The production and the properties of nuclei in extreme conditions, such as high isospin, temperature, angular momenta, large deformations etc., have become the subject of detailed investigations in all scientific centers. The main topics discussed at the Symposium were: Synthesis and Properties of Exotic Nuclei; Superheavy Elements; Rare Processes, Nuclear Reactions, Fission and Decays; Experimental Facilities and Scientific Projects. This book provides a comprehensive overview of the newest results of the investigations in the main scientific centers such as GSI (Darmstadt, Germany), GANIL (Caen, France), RIKEN (Wako-shi, Japan), MSU (Michigan, USA), and JINR (Dubna, Russia).
Accardi, Alberto
2016-01-01
I review recent progress in the extraction of unpolarized parton distributions in the proton and in nuclei from a unified point of view that highlights how the interplay between high energy particle physics and lower energy nuclear physics can be of mutual benefit to either field. Areas of overlap range from the search for physics beyond the standard model at the LHC, to the study of the non perturbative structure of nucleons and the emergence of nuclei from quark and gluon degrees of freedom, to the interaction of colored probes in a cold nuclear medium.
Spontaneous fission of superheavy nuclei
Indian Academy of Sciences (India)
R A Gherghescu; D N Poenaru
2015-09-01
The macroscopic–microscopic method is extended to calculate the deformation energy and penetrability for binary nuclear configurations typical for fission processes. The deformed two-centre shell model is used to obtain single-particle energy levels for the transition region of two partially overlapped daughter and emitted fragment nuclei. The macroscopic part is obtained using the Yukawa-plus-exponential potential. The microscopic shell and pairing corrections are obtained using the Strutinsky and BCS approaches and the cranking formulae yield the inertia tensor. Finally, the WKB method is used to calculate penetrabilities and spontaneous fission half-lives. Calculations are performed for the decay of 282,292120 nuclei.
Unstable nuclei in dissociation of light stable and radioactive nuclei in nuclear track emulsion
Artemenkov, D A; Zarubin, P I
2016-01-01
A role of the unstable nuclei ${}^{6}$Be, ${}^{8}$Be and ${}^{9}$B in the dissociation of relativistic nuclei ${}^{7,9}$Be, ${}^{10}$B and ${}^{10,11}$C is under study on the basis of nuclear track emulsion exposed to secondary beams of the JINR Nuclotron. Contribution of the configuration ${}^{6}$Be + $\\mit{n}$ to the ${}^{7}$Be nucleus structure is 8 $\\pm$ 1% which is near the value for the configuration ${}^{6}$Li + $\\mit{p}$. Distributions over the opening angle of $\\alpha$-particle pairs indicate to a simultaneous presence of virtual ${}^{8}$Be$_{g.s.}$ and ${}^{8}$Be$_{2^+}$ states in the ground states of the ${}^{9}$Be and ${}^{10}$C nuclei. The core ${}^{9}$B is manifested in the {${}^{10}$C} nucleus with a probability of 30 $\\pm$ 4%. Selection of the ${}^{10}$C "white" stars accompanied by ${}^{8}$Be$_{g.s.}$ (${}^{9}$B) leads to appearance in the excitation energy distribution of 2$\\alpha$2$\\mit{p}$ "quartets" of the distinct peak with a maximum at 4.1 $\\pm$ 0.3 MeV. ${}^{8}$Be$_{g.s.}$ decays are p...
Neutrino Interactions with Nuclei
Leitner, T; Mosel, U; Alvarez-Ruso, L
2007-01-01
We investigate neutrino-nucleus collisions at intermediate energies incorporating quasi-elastic scattering and the excitation of 13 resonances as elementary processes, taking into account medium effects such as Fermi motion, Pauli blocking, mean-field potentials and in-medium spectral functions. A coupled-channel treatment of final state interactions is achieved with the GiBUU transport model. Results for inclusive reactions, neutrino- and electron-induced, as well as for pion production and nucleon knockout are presented.
A Search for "Dwarf" Seyfert Nuclei. VI. Properties of Emission-Line Nuclei in Nearby Galaxies
Ho, L C; Sargent, W L W; Ho, Luis C.; Filippenko, Alexei V.; Sargent, Wallace L. W.
2003-01-01
We use the database from Paper III to quantify the global and nuclear properties of emission-line nuclei in the Palomar spectroscopic survey of nearby galaxies. We show that the host galaxies of Seyferts, LINERs, and transition objects share remarkably similar large-scale properties and local environments. The distinguishing traits emerge on nuclear scales. Compared with LINERs, Seyfert nuclei are an order of magnitude more luminous and exhibit higher electron densities and internal extinction. We suggest that Seyfert galaxies possess characteristically more gas-rich circumnuclear regions, and hence a more abundant fuel reservoir and plausibly higher accretion rates. The differences between the ionization state of the narrow emission-line regions of Seyferts and LINERs can be partly explained by the differences in their nebular properties. Transition-type objects are consistent with being composite (LINER/\\hii) systems. With very few exceptions, the stellar population within the central few hundred parsecs of...
Fission barrier in even-even superheavy nuclei
International Nuclear Information System (INIS)
In this work, the ground state properties of even-even superheavy nuclei (Z=112-120) are studied. The work has given emphasis on the role of deformation on the structure of superheavy nuclei. The problem of superdeformed ground state, their deformation energy curves and the potential energy surface of these nuclei is addressed. Both the nonrelativistic Skyrme-Hartree-Fock SHF and the deformed Relativistic Mean Field RMF models have been used in a constrained calculation. The systematic investigations of fission barriers in even-even superheavy nuclei with charge number Z=112-120 within relativistic mean field theory including the triaxial shapes and octupole shapes with axial symmetry. The improved version of NL3 parameter set (NL3), standard NL3, SkI4 and SLy4 parameter sets are used for the calculations. The pairing correlations are treated using the BCS approximation using the seniority pairing forces adjusted to empirical values of the gap parameters. The investigations for potential energy surface (PES), and the deformation energy curves for several isotopes with charge number Z=112, 114, 116, 118 and 120 nuclei obtained with the NL3 parameterization of the RMF Lagrangian is presented. The results will be for the case of axial solution with reflection symmetry, triaxial solutions with reflection symmetry, and octupole deformation solutions with axial symmetry
Institute of Scientific and Technical Information of China (English)
曹李刚; 马中玉
2003-01-01
A fully consistent relativistic random-phase approximation is applied to study the systematic behaviour of the isovector giant dipole resonance of nuclei along the β-stability line in order to test the effective Lagrangians recently developed. The centroid energies of response functions of the isovector giant dipole resonance for stable nuclei are compared with the corresponding experimental data and the good agreement is obtained. It is found that the effective Lagrangian with an appropriate nuclear symmetry energy, which can well describe the ground state properties of nuclei, could also reproduce the isovector giant dipole resonance of nuclei along the β-stability line.
Light Nuclei of Even Mass Number in the Skyrme Model
Battye, Richard A.; Manton, Nicholas S.; Sutcliffe, Paul M.; Wood, Stephen W.
2009-01-01
We consider the semiclassical rigid-body quantization of Skyrmion solutions of mass numbers B = 4, 6, 8, 10 and 12. We determine the allowed quantum states for each Skyrmion, and find that they often match the observed states of nuclei. The spin and isospin inertia tensors of these Skyrmions are accurately calculated for the first time, and are used to determine the excitation energies of the quantum states. We calculate the energy level splittings, using a suitably chosen parameter set for e...
Algebraic benchmark for prolate-oblate coexistence in nuclei
Leviatan, A
2016-01-01
We present a symmetry-based approach for prolate-oblate and spherical-prolate-oblate shape coexistence, in the framework of the interacting boson model of nuclei. The proposed Hamiltonian conserves the SU(3) and $\\overline{\\rm SU(3)}$ symmetry for the prolate and oblate ground bands and the U(5) symmetry for selected spherical states. Analytic expressions for quadrupole moments and $E2$ rates involving these states are derived and isomeric states are identified by means of selection rules.
A new superfluid phase in atomic nuclei
International Nuclear Information System (INIS)
The influence of pairing and the dynamical α-type correlations on the structure of nuclear states is studied within the enlarged superfluid model (ESM). A comparison between ESM and different modern nuclear structure models such as: the quasiparticle-phonon nuclear model, interaction boson model, Hartree-Fock-Bogoliubov, temperature dependent Hartree-Fock-Bogoliubov and Migdal's finite Fermi system model, is done for particular cases. New gap equations are obtained. The phase structure is enriched by a new superfluid phase - the so-called α-like superfluid phase-dominated by α-type correlations. New first and second order phase transitions are predicted. A first order phase transition between the α-like superfluid phase and the pairing superfluid phase seems to be observed in Sm region. New types of isomers, the so-called ''superfluid isomers'', with their bands of elementary excitations are predicted. One of them is observed in 152Sm. These isomers correspond to a second (local) minimum of the correlation energy versus pairing deformations, analogous to the fission or superdeformed (shape) isomers, which correspond to the second (local) minimum of the potential energy along the elongation degree of shape deformation. The superfluidities of neutron and proton systems in heavy nuclei region may be generated by one another. This fact leads to the explanation of the origin of the odd-even staggering of the charge radii of chains of isotopes of different nuclei. The fact that the magnitude of the α-decay reduced widths (γ2) of the neutron-defficient Pb isotopes is almost equal to the γ2 of the actinide α-decaying nuclei is due to the above mentioned induction of the neutron superfluidity into the proton system also. Such exotic data ESM can explain especially in the region of single magic nuclei. Within ESM we could find a natural microscopic description of the scissors mode that dominates the structure of the Kπ=1+ magnetic states. (author). 89 refs, 27 figs
International Nuclear Information System (INIS)
The possibility of connecting apparently different descriptions of quarks in nuclei has already been shown. The authors pursue the consequences of this 'duality' for flavour-singlet distributions. An interesting possibility is that nuclear pions may have unusual quark-gluon substructure. Indeed, pions in general could be relatively 'rich' in glue. (author)
Fission dynamics of hot nuclei
Indian Academy of Sciences (India)
Santanu Pal; Jhilam Sadhukhan
2014-04-01
Experimental evidence accumulated during the last two decades indicates that the fission of excited heavy nuclei involves a dissipative dynamical process. We shall briefly review the relevant dynamical model, namely the Langevin equations for fission. Statistical model predictions using the Kramers’ fission width will also be discussed.
Generalized parton distributions of nuclei
Guzey, V.
2009-01-01
We review recent theoretical results on generalized parton distributions (GPDs) of nuclei, emphasizing the following three roles of nuclear GPDs: (i) complementarity to free proton GPDs, (ii) the enhancement of traditional nuclear effects such as nuclear binding, EMC effect, nuclear shadowing, and (iii) an access to novel nuclear effects such as medium modifications of bound nucleons.
Percolation and multifragmentation of nuclei
International Nuclear Information System (INIS)
A method to build the 'cold' nuclei as percolation clusters is suggested. Within the framework of definite assumptions of the character of nucleon-nucleon couplings breaking resulting from the nuclear reactions as description of the multifragmentation process in the hadron-nucleus and nucleus-nucleus reactions at high energies is obtained. 19 refs.; 6 figs
Chiral Electroweak Currents in Nuclei
Riska, D O
2016-01-01
The development of the chiral dynamics based description of nuclear electroweak currents is reviewed. Gerald E. (Gerry) Brown's role in basing theoretical nuclear physics on chiral Lagrangians is emphasized. Illustrative examples of the successful description of electroweak observables of light nuclei obtained from chiral effective field theory are presented.
Static multipole deformations in nuclei
International Nuclear Information System (INIS)
The physics of static multipole deformations in nuclei is reviewed. Nuclear static moments result from the delicate balance between the vibronic Jahn-Teller interaction (particle-vibration coupling) and the residual interaction (pairing force). Examples of various permanent nuclear deformations are discussed
Nuclear astrophysics of light nuclei
DEFF Research Database (Denmark)
Fynbo, Hans Otto Uldall
2013-01-01
A review of nuclear astrophysics of light nuclei using radioactive beams or techniques developed for radioactive beams is given. We discuss Big Bang nucleosynthesis, with special focus on the lithium problem, aspects of neutrino-physics, helium-burning and finally selected examples of studies...
Partial Dynamical Symmetries in Nuclei
Leviatan, A
2000-01-01
Partial dynamical symmetries (PDS) are shown to be relevant to the interpretation of the $K=0_2$ band and to the occurrence of F-spin multiplets of ground and scissors bands in deformed nuclei. Hamiltonians with bosonic and fermionic PDS are presented.
Octupole correlation effects in nuclei
International Nuclear Information System (INIS)
Octupole correlation effects in nuclei are discussed from the point of view of many-body wavefunctions as well as mean-field methods. The light actinides, where octupole effects are largest, are considered in detail. Comparisons of theory and experiment are made for energy splittings of parity doublets; E1 transition matrix elements and one-nucleon transfer reactions
Magnetic shift of magic nuclei
International Nuclear Information System (INIS)
The shell effect of nuclei in strong magnetic fields associated with magnetars' is considered within the shell model. It is demonstrated that the magnetic field gives rise to a change of the phase in shell-oscillations of nuclear masses. The nuclear magic numbers of the iron region are shifted significantly towards smaller mass numbers. (author)
Low energy + scattering on = nuclei
Indian Academy of Sciences (India)
Swapan Das; Arun K Jain
2003-11-01
The data for the total cross-section of + scattering on various nuclei have been analysed in the Glauber multiple scattering theory. Energy-dependent +-nucleus optical potential is generated using the forward +-nucleon scattering amplitude and the nuclear density distribution. Along with this, the calculated total +-nucleus cross-sections using the effective +-nucleon cross-section inside the nucleus are also presented.
Stripping reactions of neutron rich 11Be and 19C nuclei
International Nuclear Information System (INIS)
In recent times, the stripping reactions measuring the longitudinal momentum distribution and absorption cross section have been used as a prolific tool to investigate the ground state properties of neutron rich nuclei. The nuclei 11Be and 19C, being paradigm for single neutron halo, have attracted a significant interest, both theoretically as well as experimentally
Lattice effective field theory for nuclei from A = 4 to A = 28
Lähde, Timo A; Krebs, Hermann; Lee, Dean; Meißner, Ulf-G; Rupak, Gautam
2013-01-01
We present an overview of the extension of Nuclear Lattice Effective Field Theory simulations to the regime of medium-mass nuclei. We focus on the determination of the ground-state energies of the alpha nuclei $^{16}$O, $^{20}$Ne, $^{24}$Mg and $^{28}$Si by means of Euclidean time projection.
Status and Perspectives of the Search for Eta-Mesic Nuclei
Moskal, Pawel; Krzemien, Wojciech
2016-01-01
In this report the search for eta-mesic nuclei is reviewed. The brief description of the experimental studies is presented with a focus on the possible production of the eta-nucleus bound states for light nuclei like 4He and 3He.
Description of Superdeformed Bands of the Nuclei in A ～ 60 Mass Region
Institute of Scientific and Technical Information of China (English)
刘玉鑫; 孟祥明
2003-01-01
Using the supersymmetry scheme including many-body interactions, we investigate the superdeformed (SD) bands of the nuclei in A ～ 60 mass region systematically. Quantitatively good results of the γ-ray energy spectra and the dynamical moments of inertia are obtained. It shows that the supersymmetry approach is powerful to describe the generic rotational property of SD states of light nuclei.
International Nuclear Information System (INIS)
The present collection of letters from JINR, Dubna, contains eight separate letters on analysis of experimental data on relativistic nuclear collisions in the Lobachevski space, relativistic contribution of the final-state interaction to deuteron photodisintegration, on the charge asymmetry of the like-sign lepton pairs induced by B - B bar - production asymmetry, limits on the νe → νe neutrino oscillation parameters from an experiment at the IHEP-JINR neutrino detector, excitation of high spin isomers in photonuclear reactions, study of product formation in proton-nuclear reactions on the 129I target induced by 660-MeV protons, application of jet pumps in the cryogenic system of the Nuclotron - superconducting accelerator of relativistic particles and study of the silicon drift detector performance with inclined tracks
Neutrino interactions with nuclei
Leitner, T; Mosel, U; Alvarez-Ruso, L
2008-01-01
Current long baseline experiments aim at measuring neutrino oscillation parameters with a high precision. A critical quantity is the neutrino energy which can not be measured directly but has to be reconstructed from the observed hadrons. A good knowledge of neutrino-nucleus interactions is thus necessary to minimize the systematic uncertainties in neutrino fluxes, backgrounds and detector responses. In particular final-state interactions inside the target nucleus modify considerably the particle yields through rescattering, charge-exchange and absorption. Nuclear effects can be described with our coupled channel GiBUU transport model where the neutrino first interacts with a bound nucleon producing secondary particles which are then transported out of the nucleus. In this contribution, we give some examples for the application of our model focusing in particular on the MiniBooNE and K2K experiments.
Auxiliary-field quantum Monte Carlo methods in nuclei
Alhassid, Y
2016-01-01
Auxiliary-field quantum Monte Carlo methods enable the calculation of thermal and ground state properties of correlated quantum many-body systems in model spaces that are many orders of magnitude larger than those that can be treated by conventional diagonalization methods. We review recent developments and applications of these methods in nuclei using the framework of the configuration-interaction shell model.
Relativistic Pseudospin Symmetry as a Supersymmetric Pattern in Nuclei
Leviatan, A
2004-01-01
Shell-model states involving several pseudospin doublets and ``intruder'' levels in nuclei, are combined into larger multiplets. The corresponding single-particle spectrum exhibits a supersymmetric pattern whose origin can be traced to the relativistic pseudospin symmetry of a nuclear mean-field Dirac Hamiltonian with scalar and vector potentials.
Investigation of exotic nuclei with absolute transition probabilities
International Nuclear Information System (INIS)
Transition probabilities are crucial for the understanding of nuclear structure. Deep inelastic reactions, knockout reactions and projectile Coulomb excitation with fast radioactive beams are suited to populate excited states in exotic nuclei. Examples are presented which demonstrate that recoil Doppler shift lifetime measurements can be applied successfully in combination with such reactions to measure level lifetimes.
Towards a microscopic description of α-condensates in nuclei
International Nuclear Information System (INIS)
A theory to describe α-condensates in nuclei is presented. The corresponding quasiparticles consist of fermions as well as bosons. The fermions are combinations of one-particle and three-hole states, while the bosons are combinations of pair-particles and pair-holes. A relation between the fermionic and bosonic gap parameters is predicted and confirmed by experimental data. (authors)
Collective properties of octupole-deformed atomic nuclei
International Nuclear Information System (INIS)
Collective properties of even-even nuclei in the radium region are studied theoretically. Energy of the lowest collective states and reduced probabilities B(E2) and B(E3) of electromagnetic transitions between these states are mainly analysed. The excited states are treated as large-amplitude quadrupole and octupole vibrations coupled with each other. A large anharmonicity of the spectrum and a large value B(E3) of the transition from the first octupole excited state to the ground state are obtained, for octupole-deformed nuclei. A strong dependence of the results on the shape of the potential energy of a nucleus, treated as a function of its deformation, is stressed. (author)
Nuclei at extreme conditions. A relativistic study
Energy Technology Data Exchange (ETDEWEB)
Afanasjev, Anatoli [Mississippi State Univ., Mississippi State, MS (United States)
2014-11-14
The major goals of the current project were further development of covariant density functional theory (CDFT), better understanding of its features, its application to different nuclear structure and nuclear astrophysics phenomena and training of graduate and undergraduate students. The investigations have proceeded in a number of directions which are discussed in detail in the part “Accomplishments” of this report. We have studied the role of isovector and isoscalar proton-neutron pairings in rotating nuclei; based on available experimental data it was concluded that there are no evidences for the existence of isoscalar proton-neutron pairing. Generalized theoretical approach has been developed for pycnonuclear reaction rates in the crust of neutron stars and interior of white dwarfs. Using this approach, extensive database for considerable number of pycnonuclear reactions involving stable and neutron-rich light nuclei has been created; it can be used in future for the study of various nuclear burning phenomena in different environments. Time-odd mean fields and their manifestations in terminating states, non-rotating and rotating nuclei have been studied in the framework of covariant density functional theory. Contrary to non-relativistic density functional theories these fields, which are important for a proper description of nuclear systems with broken time-reversal symmetry, are uniquely defined in the CDFT framework. Hyperdeformed nuclear shapes (with semi-axis ratio 2.5:1 and larger) have been studied in the Z = 40-58 part of nuclear chart. We strongly believe that such shapes could be studied experimentally in the future with full scale GRETA detector.
Four-body correlations in heavy nuclei
International Nuclear Information System (INIS)
The origin of four-body correlations in heavy nuclei is studied. It is found that the physical picture for this phenomenon can be different in heavy and light nuclei. An application to the /sup 208/Pb region is made
Thermodynamics of pairing transition in hot nuclei
Liu, Lang; Zhao, Peng-Wei
2014-01-01
The pairing correlations in hot nuclei $^{162}$Dy are investigated in terms of the thermodynamical properties by covariant density functional theory. The heat capacities $C_V$ are evaluated in the canonical ensemble theory and the paring correlations are treated by a shell-model-like approach, in which the particle number is conserved exactly. A S-shaped heat capacity curve, which agrees qualitatively with the experimental data, has been obtained and analyzed in details. It is found that the one-pair-broken states play crucial roles in the appearance of the S shape of the heat capacity curve. Moreover, due to the effect of the particle-number conservation, the pairing gap varies smoothly with the temperature, which indicates a gradual transition from the superfluid to the normal state.
Halo exotic nuclei and Schroedingers's cat
International Nuclear Information System (INIS)
A 'doorway' description of Ε1 transitions in the Coulomb excitation of 'halo'exotic nuclei is formulated. The 'doorway'is defined as that (normalizable, non-stationary) state which can be reached from the ground state through the action of the relevant transition operator. In this picture, the Coulomb excitation process naturally appears in the form of a non Breit-Wigner resonance production process, while the so called 'soft'and 'hard' dipole modes can be related to the non standard spectral distribution of the doorway in its host physical system. Coherence and decoherence effects involving the different spectral components in fast Coulomb excitation processes and photon inelastic scattering are briefly discussed. (author)
Momentum distribution of N$^*$ in nuclei
Kelkar, N G
2016-01-01
Due to its dominance in the low energy eta-nucleon interaction, the S11 N$^*$(1535) resonance enters as an important ingredient in the analyses of experiments aimed at finding evidence for the existence of eta-mesic nuclei. The static properties of the resonance get modified inside the nucleus and its momentum distribution is used in deciding these properties as well as the kinematics in the analyses. Here we show that given the possibility for the existence of an N$^*$-$^3$He quasibound state, the relative momentum distribution of an N$^*$ and $^3$He inside such a $^4$He is narrower than that of neutron-$^3$He in $^4$He. Results for the N$^*$-$^{24}$Mg system are also presented. The present exploratory work could be useful in motivating searches of exotic N$^*$-nucleus quasibound states as well as in performing analyses of eta meson production data.
Liquid layer model for non-magic nuclei
International Nuclear Information System (INIS)
A liquid layer model (LLM) is developed for studying the low-energy oscillations of non-magic spherical nuclei. It is assumed that at low excitations only nucleons off the double-magic core take part in the collective motion. These nuclear states are modellized by the motion of a layer of homogeneously charged, incompressible, isotropic liquid around a solid, inert core. Inertia, stiffness and energies of the lowest quadrupole, octupole and hexadecapole excitations are calculated. A fairly good agreement between the calculated and experimental values are obtained in the validity regions of LLM, that is for near magic nuclei. (author) 29 refs.; 5 figs
Relativistic mean field study of clustering in light nuclei
International Nuclear Information System (INIS)
The clustering phenomenon in light, stable and exotic nuclei is studied within the relativistic mean field (RMF) approach. Numerical calculations are done by using the axially deformed harmonic oscillator basis. The calculated nucleon density distributions and deformation parameters are analyzed to look for the cluster configurations. The calculations explain many of the well-established cluster structures in both the ground and intrinsic excited states. Comparisons of our results with other model calculations and the available experimental information suggest that the RMF theory is well suited for studying clustering in light nuclei. A few discrepancies and their possible sources are also discussed
Neutrino pair emission from thermally excited nuclei in stellar collapse
Dzhioev, Alan A
2013-01-01
We examine the rate of neutrino-antineutrino pair emission by hot nuclei in collapsing stellar cores. The rates are calculated assuming that only allowed charge-neutral Gamow-Teller (GT$_0$) transitions contribute to the decay of thermally excited nuclear states. To obtain the GT$_0$ transition matrix elements, we employ the quasiparticle random phase approximation extended to finite temperatures within the thermo field dynamics formalism. The decay rates and the energy emission rates are calculated for the sample nuclei ${}^{56}$Fe and $^{82}$Ge at temperatures relevant to core collapse supernovae.
Repolarization of Negative Muons by Polarized $^{209}$Bi Nuclei
Kadono, R; Ishikawa, T; Nishiyama, K; Nagamine, K; Yamazaki, T; Bosshard, A; Döbeli, M; van Elmbt, L; Schaad, M; Truöl, P; Bay, A; Perroud, J P; Deutsch, J; Tasiaux, B; Hagn, E
2016-01-01
A large $\\mu^-$ polarization was achieved in muonic Bi atoms with the help of the strong hyperfine field in a polarized nuclear target. Using $^{209}$Bi nuclei polarized to ($59\\pm9$)% in ferromagnetic BiMn, we observed a $\\mu$-$e$ decay asymmetry of ($13.1\\pm3.9$)%, which gives $\\mu^-$ polarization per nuclear polarization equal to $-1.07\\pm 0.35$. This value is almost consistent with $-0.792$ calculated for nuclei with spin $I= \\frac{9}{2}$ and a positive magnetic moment under the assumption that the hyperfine interaction becomes effective in the lowest muonic states.
Modes of decay in neutron-rich nuclei
Kumar, B.; Biswal, S. K.; Singh, S. K.; Lahiri, C.; Patra, S. K.
2016-03-01
We calculate the ground, first intrinsic excited states and density distribution for neutron-rich thorium and uranium isotopes, within the framework of relativistic mean field (RMF) approach using axially deformed basis. The total nucleon densities are calculated, from which the cluster-structures inside the parent nuclei are determined. The possible modes of decay, like α-decay and β-decay are analyzed. We find the neutron-rich isotopes are stable against α-decay, however they are very much unstable against β-decay. The life time of these nuclei predicted to be tens of second against β-decay.
Modes of decay in neutron-rich nuclei
Kumar, B; Singh, S K; Lahiri, C; Patra, S K
2016-01-01
We calculate the ground, first intrinsic excited states and density distribution for neutron-rich thorium and uranium isotopes, within the framework of relativistic mean field(RMF) approach using axially deformed basis. The total nucleon densities are calculated, from which the cluster-structures inside the parent nuclei are determined. The possible modes of decay, like {\\alpha}-decay and \\b{eta} -decay are analyzed. We find the neutron-rich isotopes are stable against {\\alpha}-decay, however they are very much unstable against \\b{eta} -decay. The life time of these nuclei predicted to be tens of second against \\b{eta} -decay.
Stability of bubble nuclei through Shell-Effects
Dietrich, Klaus; Pomorski, Krzysztof
1997-01-01
We investigate the shell structure of bubble nuclei in simple phenomenological shell models and study their binding energy as a function of the radii and of the number of neutron and protons using Strutinsky's method. Shell effects come about, on the one hand, by the high degeneracy of levels with large angular momentum and, on the other, by the big energy gaps between states with a different number of radial nodes. Shell energies down to -40 MeV are shown to occur for certain magic nuclei. E...
Magnetic moments of odd-odd spherical nuclei
Achakovskiy, O. I.; Kamerdzhiev, S. P.; Saperstein, E. E.; Tolokonnikov, S. V.
2013-01-01
Magnetic moments of more than one hundred odd-odd spherical nuclei in ground and excited states are calculated within the self-consistent TFFS based on the EDF method by Fayans {\\it et al}. We limit ourselves to nuclei with a neutron and a proton particle (hole) added to the magic or semimagic core. A simple model of no interaction between the odd nucleons is used. In most the cases we analyzed, a good agreement with the experimental data is obtained. Several cases are considered where this s...
Comparing and contrasting nuclei and cold atomic gases
DEFF Research Database (Denmark)
Zinner, Nikolaj Thomas; Jensen, Aksel Stenholm
2013-01-01
The experimental revolution in ultracold atomic gas physics over the past decades has brought tremendous amounts of new insight to the world of degenerate quantum systems. Here we compare and contrast the developments of cold atomic gases with the physics of nuclei since many concepts, techniques...... physics transferred to cold atoms, and consider which systems are more likely to show interesting bound state spectra. Finally, we address some recent studies of the BCS–BEC crossover in light nuclei and compare them to the concepts used in ultracold atomic gases. While many-body concepts such as BEC...
General Relativistic Mean Field Theory for rotating nuclei
Energy Technology Data Exchange (ETDEWEB)
Madokoro, Hideki [Kyushu Univ., Fukuoka (Japan). Dept. of Physics; Matsuzaki, Masayuki
1998-03-01
The {sigma}-{omega} model Lagrangian is generalized to an accelerated frame by using the technique of general relativity which is known as tetrad formalism. We apply this model to the description of rotating nuclei within the mean field approximation, which we call General Relativistic Mean Field Theory (GRMFT) for rotating nuclei. The resulting equations of motion coincide with those of Munich group whose formulation was not based on the general relativistic transformation property of the spinor fields. Some numerical results are shown for the yrast states of the Mg isotopes and the superdeformed rotational bands in the A {approx} 60 mass region. (author)
Energy Technology Data Exchange (ETDEWEB)
Gulminelli, F
2003-05-01
In this work the general theory of first order phase transitions in finite systems is discussed, with a special emphasis to the conceptual problems linked to a thermodynamic description for small, short-lived systems de-exciting in the vacuum as nuclear samples coming from heavy ion collisions. After a short review of the general theory of phase transitions in the framework of information theory; we will present the different possible extensions to the field of finite systems. The concept of negative heat capacity, developed in the early seventies in the context of self-gravitating systems, will be reinterpreted in the general framework of convexity anomalies of thermo-statistical potentials. The connection with the distribution of the order parameter will lead us to a definition of first order phase transitions in finite systems based on topology anomalies of the event distribution in the space of observations. A careful study of the thermodynamic limit will provide a bridge with the standard theory of phase transitions and show that in a wide class of physical situations the different statistical ensembles are irreducibly inequivalent. In the second part of the paper we will apply the theoretical ideas developed in the first part to the possible observation of a liquid-to-gas-like phase transition in heavy ion collisions. The applicability of equilibrium concepts in a dynamical collisional process without boundary conditions will first be critically discussed. The observation of abnormally large partial energy fluctuations in carefully selected samples of collisions detected with the MULTICS-Miniball array will then be reported as a strong evidence of a first order phase transition with negative heat capacity in the nuclear equation of state. (author)
Quadrupole deformation and clusterization in nuclei
International Nuclear Information System (INIS)
The investigation of exotic nuclear shapes, e.g. superdeformed and hyperdeformed states (in which the atomic nucleus has a spheroidal shape with ratios of main axes of 2:1 and 3:1, respectively) is one of the most interesting topics in recent nuclear structure studies. The appearance of exotic cluster configurations (or exotic cluster decay) is another issue of utmost interest. The combination of these two problems brings us to an exciting question: what is the interrelation of these two phenomena, i.e. what are the possible clusterizations of nuclear states with exotic shape. Recently we have addressed this question from the angle of both the binary and the ternary clusterizations. We apply methods which can be generalised for more complicated multicluster-configurations in a straightforward way. The basic concept of this work is that when we describe the composition of an atomic nucleus from smaller nuclei (clusters) then we take into account both of the two complementary natural laws, which govern this kind of phenomenon: the energy-minimum principle and the Pauli-exclusion principle. The crucial role of these two rules are obvious: energetically unfavoured systems are not likely to appear, and when the building blocks are fermions, like the nucleons of the atomic nuclei, then they follow the exclusion principle. However, the exact role, or relative importance of these two aspects of clusterization among di rent circumstances are not completely understood yet; the present work is meant to be a contribution to this task. Much attention has been paid to the energetic preference of various cluster-configurations of a nucleus. The methods applied along this line are partly or completely empirical ones, using information of the experimental data. Furthermore, most of these works concentrate on the simplest, i.e. binary clusterizations, especially, when the energetic calculation involves (in addition to the experimental binding energies) intercluster potentials, like
Transmutations of atomic nuclei in hadron-nuclei nuclear collisions at GeV energies
International Nuclear Information System (INIS)
In hadron-nuclei nuclear collisions nuclei change their mass numbers A and the charge numbers Z. The mechanism of transmutation of a target nucleus was prompted experimentally and is described in this work. The information about the nuclei transmutation may be a basis for elaboration of the method of nuclei changes in beams of hadrons from accelerators
Scissors mode of Gd nuclei measured, with the DANCE detector
Kroll, J.; Bečvář, F.; Krtička, M.; Valenta, S.; Baramsai, B.; Mitchell, G. E.; Walker, C. L.; Bredeweg, T. A.; Couture, A.; Haight, R. C.; Jandel, M.; O'Donnell, J. M.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.; Wilhelmy, J. B.; Wouters, J. M.; Becker, J. A.; Chyzh, A.; Dashdorj, D.; Parker, W.; Wu, C. Y.
2013-05-01
Spectra of γ-rays following the neutron capture at isolated resonances of stable Gd nuclei were measured with the DANCE detector. The objectives were to obtain new information on the photon strength of 153,155-159Gd with emphasis on the role of the M1 scissors-mode vibration. An analysis of the data obtained clearly indicates that the scissors mode is built not only on the ground state, but also on all excited levels of the nuclei studied. Our approach allows estimating the summed scissors-mode strength \\sum B(M1)\\!\\!\\uparrow even for odd product nuclei for which conventional nuclear resonance fluorescence measurements yield only limited information. Our data indicate that for 157,159Gd the strength \\sum B(M1)\\!\\!\\uparrow is significantly higher compared to 156,158Gd.
Scissors mode of Gd nuclei measured, with the DANCE detector
International Nuclear Information System (INIS)
Spectra of γ-rays following the neutron capture at isolated resonances of stable Gd nuclei were measured with the DANCE detector. The objectives were to obtain new information on the photon strength of 153,155−159Gd with emphasis on the role of the M1 scissors-mode vibration. An analysis of the data obtained clearly indicates that the scissors mode is built not only on the ground state, but also on all excited levels of the nuclei studied. Our approach allows estimating the summed scissors-mode strength ΣB(M1) ↑ even for odd product nuclei for which conventional nuclear resonance fluorescence measurements yield only limited information. Our data indicate that for 157,159Gd the strength ΣB(M1) ↑ is significantly higher compared to 156,158Gd. (paper)
Self-consistent calculations of quadrupole moments of spherical nuclei
Directory of Open Access Journals (Sweden)
Saperstein E.E.
2012-12-01
Full Text Available The self-consistent Theory of Finite Fermi Systems based on the Energy Density Functional byFayans et al. with the set DF3-a of parameters fixed previously is used to calculate three kinds of quadrupolemoments. At first, we examined systematically quadrupole moments of odd neighbors of semi-magic lead andtin isotopes and N = 50, N = 82 isotones. Second, we found quadrupole moments of the first 2+ states in thesame two chains of isotopes. Finally, we evaluated quadrupole moments of odd-odd nuclei neighboring to doublemagic ones. Reasonable agreement with available experimental data has been obtained. Predictions are made forquadrupole moments of nuclei in the vicinity of unstable magic nuclei
Quasi-elastic scattering of 6He, 7Be, and 8B nuclei by 12C nuclei
Kovalchuk, V I
2016-01-01
The observed cross sections of quasi-elastic scattering of 6He, 7Be, and 8B nuclei by 12C nuclei are described within the framework of the diffraction nuclear model and the model of nucleus-nucleus scattering in the high-energy approximation with a double folding potential, for intermediate energies of the incident particles. The calculations make use of realistic distributions of nucleon densities and take account of the Coulomb interaction and inelastic scattering with excitation of low-lying collective states of the target.
Efimov effect in 2-neutron halo nuclei
Indian Academy of Sciences (India)
Indranil Mazumdar
2010-07-01
This paper presents an overview of our theoretical investigations in search of Efimov states in light 2-neutron halo nuclei. The calculations have been carried out within a three-body formalism, assuming a compact core and two valence neutrons forming the halo. The calculations provide strong evidence for the occurrence of at least two Efimov states in 20C nucleus. These excited states move into the continuum as the two-body (core-neutron) binding energy is increased and show up as asymmetric resonances in the elastic scattering cross-section of the n- 19C system. The Fano mechanism is invoked to explain the asymmetry. The calculations have been extended to 38Mg, 32Ne and a hypothetical case of a very heavy core ( = 100) with two valence neutrons. In all these cases the Efimov states show up as resonances as the two-body energy is increased. However, in sharp contrast, the Efimov states, for a system of three equal masses, show up as virtual states beyond a certain value of the two-body interaction.
A quark structure of hadrons and nuclei
International Nuclear Information System (INIS)
In this review we look into the recent understanding of mesons, baryons and nuclei as few quark bound states within the framework of quantum chromodynamics (QCD). In particular, we have reviewed our understanding of the nature of confining interaction, the spin - dependence of colour forces and the role of non-perturbative effects in the study of quark forces in the potential model approach. We also give a comparative study of results obtained by several potential models with reference to the experimental data. We find that although the Lorentz nature of confinement and the nature of spin-dependent colour forces have been better understood now, only a partial understanding of these problems are obtained so far. Our study reveals that properties of baryons could be explained by the same potential model which successfully describe the mesons. However, the nuclei require chiral symmetry and non-perturbative methods for their description. We also discuss the relation between constituent, current and dynamical quark masses. We conclude that QCD motivated approaches have shown much success in explaining many results on hadronic and nuclear data. (author). 212 refs, 14 tabs
Experiments with stored relativistic exotic nuclei
International Nuclear Information System (INIS)
Beams of relativistic exotic nuclei were produced, separated and investigated with the combination of the fragment separator FRS and the storage ring ESR. The following experiments are presented: (1) Direct mass measurements of relativistic nickel and bismuth projectile fragments were performed using Schottky spectrometry. Applying electron cooling, the relative velocity spread of the circulating secondary nuclear beams of low intensity was reduced to below 10-6. The achieved mass resolving power of m/Δm = 6.5 . 105 (FWHM) in recent measurements represents an improvement by a factor of two compared to our previous experiments. The previously unknown masses of more than 100 proton-rich isotopes have been measured in the range of 54 ≤ Z ≤ 84. The results are compared with mass models and estimated values based on extrapolations of experimental values. (2) Exotic nuclei with half-lives shorter than the time required for electron cooling can be investigated by time-of-flight measurements with the ESR being operated in the isochronous mode. This novel experimental technique has been successfully applied in a first measurement with nickel fragments. A mass resolving power of m/Δm = 1.5 . 105 (FWHM) was achieved in this mode of operation. (3) Nuclear half-lives of stored and cooled bare projectile fragments have been measured to study the influence of the ionic charge state on the beta-decay probability. (orig.)
Reactions with fast radioactive beams of neutron-rich nuclei
International Nuclear Information System (INIS)
The neutron dripline has presently been reached only for the lightest nuclei up to the element oxygen. In this region of light neutron-rich nuclei, scattering experiments are feasible even for dripline nuclei by utilizing high-energy secondary beams produced by fragmentation. In the present article, reactions of high-energy radioactive beams will be exemplified using recent experimental results mainly derived from measurements of breakup reactions performed at the LAND and FRS facilities at GSI and at the S800 spectrometer at the NSCL. Nuclear and electromagnetically induced reactions allow probing different aspects of nuclear structure at the limits of stability related to the neutron-proton asymmetry and the weak binding close to the dripline. Properties of the valence-neutron wave functions are studied in the one-neutron knockout reaction, revealing the changes of shell structure when going from the beta-stability line to more asymmetric loosely bound neutron-rich systems. The vanishing of the N=8 shell gap for neutron-rich systems like 11Li and 12Be, or the new closed N=14, 16 shells for the oxygen isotopes are examples. The continuum of weakly bound nuclei and halo states can be studied by inelastic scattering. The dipole response, for instance, is found to change dramatically when going away from the valley of stability. A redistribution of the dipole strength towards lower excitation energies is observed for neutron-rich nuclei, which partly might be due to a new collective excitation mode related to the neutron-proton asymmetry. Halo nuclei in particular show strong dipole transitions to the continuum at the threshold, being directly related to the ground-state properties of the projectile. Finally, an outlook on future experimental prospects is given. (orig.)
Reactions with fast radioactive beams of neutron-rich nuclei
Energy Technology Data Exchange (ETDEWEB)
Aumann, T. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany)
2005-11-01
The neutron dripline has presently been reached only for the lightest nuclei up to the element oxygen. In this region of light neutron-rich nuclei, scattering experiments are feasible even for dripline nuclei by utilizing high-energy secondary beams produced by fragmentation. In the present article, reactions of high-energy radioactive beams will be exemplified using recent experimental results mainly derived from measurements of breakup reactions performed at the LAND and FRS facilities at GSI and at the S800 spectrometer at the NSCL. Nuclear and electromagnetically induced reactions allow probing different aspects of nuclear structure at the limits of stability related to the neutron-proton asymmetry and the weak binding close to the dripline. Properties of the valence-neutron wave functions are studied in the one-neutron knockout reaction, revealing the changes of shell structure when going from the beta-stability line to more asymmetric loosely bound neutron-rich systems. The vanishing of the N=8 shell gap for neutron-rich systems like {sup 11}Li and {sup 12}Be, or the new closed N=14, 16 shells for the oxygen isotopes are examples. The continuum of weakly bound nuclei and halo states can be studied by inelastic scattering. The dipole response, for instance, is found to change dramatically when going away from the valley of stability. A redistribution of the dipole strength towards lower excitation energies is observed for neutron-rich nuclei, which partly might be due to a new collective excitation mode related to the neutron-proton asymmetry. Halo nuclei in particular show strong dipole transitions to the continuum at the threshold, being directly related to the ground-state properties of the projectile. Finally, an outlook on future experimental prospects is given. (orig.)
Evolution of active galactic nuclei
Merloni, Andrea
2012-01-01
[Abriged] Supermassive black holes (SMBH) lurk in the nuclei of most massive galaxies, perhaps in all of them. The tight observed scaling relations between SMBH masses and structural properties of their host spheroids likely indicate that the processes fostering the growth of both components are physically linked, despite the many orders of magnitude difference in their physical size. This chapter discusses how we constrain the evolution of SMBH, probed by their actively growing phases, when they shine as active galactic nuclei (AGN) with luminosities often in excess of that of the entire stellar population of their host galaxies. Following loosely the chronological developments of the field, we begin by discussing early evolutionary studies, when AGN represented beacons of light probing the most distant reaches of the universe and were used as tracers of the large scale structure. This early study turned into AGN "Demography", once it was realized that the strong evolution (in luminosity, number density) of ...
International Nuclear Information System (INIS)
We describe recent efforts to study Cooper pairs in atomic nuclei. We consider a self-consistent Hartree Fock mean field for the even Sm isotopes and compare results based on three treatments of pairing correlations: a BCS treatment, a number-projected BCS treatment and an exact treatment using the Richardson Ansatz. Significant differences are seen in the pairing correlation energies. Furthermore, because it does not average over the properties of the fermion pairs, the Richardson solution permits a more meaningful definition of the Cooper wave function and of the fraction of pairs that are collective. Our results confirm that only a few pairs near the Fermi surface in realistic atomic nuclei are collective. (Author)
Energy Technology Data Exchange (ETDEWEB)
Pittel, S. [Bartol Research Institute and Department of Physics and Astronomy, University of Delaware, Newark, 19716 Delaware (United States); Dussel, G. G. [Departamento de Fisica J.J. Giambiagi, Universidad de Buenos Aires, 1428 Buenos Aires (Argentina); Dukelsky, J.; Sarriguren, P. [Instituto de Estructura de la Materia, CSIC, Serrano 123, 28006 Madrid (Spain)
2008-12-15
We describe recent efforts to study Cooper pairs in atomic nuclei. We consider a self-consistent Hartree Fock mean field for the even Sm isotopes and compare results based on three treatments of pairing correlations: a BCS treatment, a number-projected BCS treatment and an exact treatment using the Richardson Ansatz. Significant differences are seen in the pairing correlation energies. Furthermore, because it does not average over the properties of the fermion pairs, the Richardson solution permits a more meaningful definition of the Cooper wave function and of the fraction of pairs that are collective. Our results confirm that only a few pairs near the Fermi surface in realistic atomic nuclei are collective. (Author)
Relativistic description of deformed nuclei
International Nuclear Information System (INIS)
The author has shown that relativistic Hartree calculations using parameters that have been fit to the properties of nuclear matter can provide a good description of both spherical and axially deformed nuclei. The quantitative agreement with experiment is equivalent to that which was obtained in non-relativistic calculations using Skyrme interactions. The equilibrium deformation is strongly correlated with the size of the spin-orbit splitting, and that parameter sets which give roughly the correct value for this splitting provide the best agreement with the quadrupole moments in the s-d shell. Finally, for closed shell +/- 1 nuclei, it was shown that the self-consistent calculations are able to reproduce the experimental magnetic moments. This was not possible in relativistic calculations which include only the effects of the valence orbital
Triaxial rotation in atomic nuclei
Institute of Scientific and Technical Information of China (English)
CHEN Yong-Shou; GAO Zao-Chun
2009-01-01
The Projected Shell Model has been developed to include the spontaneously broken axial symmetry so that the rapidly rotating triaxial nuclei can be described microscopically. The theory provides an useful tool to gain an insight into how a triaxial nucleus rotates, a fundamental question in nuclear structure. We shall address some current interests that are strongly associated with the triaxial rotation. A feasible method to explore the problem has been suggested.
Neurotransmitters of the suprachiasmatic nuclei
Reghunandanan, Vallath; Reghunandanan, Rajalaxmy
2006-01-01
There has been extensive research in the recent past looking into the molecular basis and mechanisms of the biological clock, situated in the suprachiasmatic nuclei (SCN) of the anterior hypothalamus. Neurotransmitters are a very important component of SCN function. Thorough knowledge of neurotransmitters is not only essential for the understanding of the clock but also for the successful manipulation of the clock with experimental chemicals and therapeutical drugs. This article reviews the c...
Proton scattering from unstable nuclei
Indian Academy of Sciences (India)
Y Blumenfeld; E Khan; F Maréchal; T Suomijärvi
2001-08-01
Recent improvements in the intensities and optical qualities of radioactive beams have made possible the study of elastic and inelastic proton scattering on unstable nuclei. The design and performances of an innovative silicon strip detector array devoted to such experiments are described. The quality of the data obtained are illustrated with recent results obtained at the GANIL facility for unstable oxygen, sulfur and argon isotopes. Methods to analyse the data using phenomenological and microscopic optical model potentials are discussed.
Weak pion production from nuclei
Indian Academy of Sciences (India)
S K Singh; M Sajjad Athar; Shakeb Ahmad
2006-04-01
The charged current pion production induced by neutrinos in 12C, 16O and 56Fe nuclei has been studied. The calculations have been done for the coherent as well as the incoherent processes assuming dominance and takes into account the effect of Pauli blocking, Fermi motion and the renormalization of in the nuclear medium. The pion absorption effects have also been taken into account.
SO8 model of collectivity in nuclei
International Nuclear Information System (INIS)
The interacting boson model (IBM) has been very successful in giving a unified and simple description of the spectroscopic properties of a wide range of nuclei, from vibrational through rotational nuclei. The three basic assumptions of the model are that (1) the valence nucleons move about a doubly closed core, (2) the collective low-lying states are composed primarily of coherent pairs of neutrons and pairs of protons coupled to angular momentum zero and two and (3) these coherent pairs are approximated as bosons. Thus the IBM is an approximation to the nuclear shell model in which the number of degrees of freedom are reduced drastically. Once these assumptions are made, the effective Hamiltonian can then be written in terms of neutron monopole (angular momentum zero) and quadrupole (angular momentum two) bosons and proton monopole and quadrupole bosons. Since each nucleus will have a fixed number of nucleon pairs this boson Hamiltonian will conserve the number of bosons. Phemonologically, the Hamiltonian is assumed to be finite and to be a sum of a boson self-energy Hamiltonian plus pairwise interactions between bosons. However, the parameters of the boson Hamiltonian depend smoothly on the mass of the nucleus. The mass dependence of these parameters presumably arise because of two effects resulting from the approximations made. In this review we shall show how it is possible to have fermion Hamiltonians which have a class of collective eigenstates composed entirely of monopole and quadrupole pairs of fermions. Hence these models satisfy the assumptions (1) and (2) above but no boson approximation need be made. Thus the Pauli principle is kept in tact. Furthermore the fermion shell model states excluded in the IBM can be classified by the number of fermion pairs which are not coherent monopole of quadrupole pairs. Hence the mixing of these states into the low-lying spectrum can be calculated in a systematic and tractable manner
PREFACE: Correlation Dynamics in Nuclei
Suzuki, Toshio; Otsuka, Takaharu; Ichimura, Munetake
2005-01-01
The International Symposium on `Correlation Dynamics in Nuclei' was held at the Sanjo Kaikan, the University of Tokyo, from the 31 January to 4 February 2005. This symposium was organized on the occasion of the 50th anniversary of the Configuration Mixing theory of Arima and Horie. The symposium was hosted by the University of Tokyo, and supported by the Inoue Foundation for Science, the Japan Atomic Energy Research Institute and the Ministry of Education, Culture, Sports, Science and Technology. The purpose of the symposium was to discuss theoretical and experimental developments and future prospects in physics of correlation dynamics in nuclei, including topics such as effective interactions, shell model studies of configuration mixing and spin-isospin modes in nuclei. It was shown in many ways and angles that the Arima-Horie theory has been a starting point of a variety of developments of the studies in these fields over many decades. The developments have been enhanced by the expansion of computational capabilities and the progress in accelerators, detectors and radioactive beam facilities. We enjoyed 28 excellent and lively invited talks and 30 oral presentations in the symposium with about 90 participants. A special session was dedicated to celebrate the 80th birthday of Professor Igal Talmi, who made invaluable and pioneering works in the shell model theory. Finally, we would like to thank all the speakers and the participants as well as the other organizers for their contributions which made the symposium very successful.
Consequences of a Relativistic Pseudospin Symmetry for Radial Nodes and Intruder Levels in Nuclei
Leviatan, A
2001-01-01
The identification of pseudospin symmetry as a relativistic symmetry of the Dirac Hamiltonian is used to explain the structure of radial nodes occurring in pseudospin doublets and to illuminate the special status of nodeless intruder states in nuclei.
Dynamical effects in fusion with exotic nuclei
Vo-Phuoc, K; Simpson, E C
2016-01-01
[Background] Reactions with stable beams have demonstrated a strong interplay between nuclear structure and fusion. Exotic beam facilities open new perspectives to understand the impact of neutron skin, large isospin, and weak binding energies on fusion. Microscopic theories of fusion are required to guide future experiments. [Purpose] To investigate new effects of exotic structures and dynamics in near-barrier fusion with exotic nuclei. [Method] Microscopic approaches based on the Hartree-Fock (HF) mean-field theory are used for studying fusion barriers in $^{40-54}$Ca+$^{116}$Sn reactions for even isotopes. Bare potential barriers are obtained assuming frozen HF ground-state densities. Dynamical effects on the barrier are accounted for in time-dependent Hartree-Fock (TDHF) calculations of the collisions. Vibrational couplings are studied in the coupled-channel framework and near-barrier nucleon transfer is investigated with TDHF calculations. [Results] The development of a neutron skin in exotic calcium iso...
Sequential binary decay of highly excited nuclei
International Nuclear Information System (INIS)
The decay of highly excited nuclei is described as a sequence of binary processes involving emission of fragments in their ground, excited-bound and unbound states. Primary together with secondary decay products lead to the final mass distributions. Asymmetric mass splittings involving nucleon emission up to symmetric binary ones are treated according to a generalized Weisskopf evaporation formalism. This procedure is implemented in the Monte-Carlo multi-step statistical model code MECO (Multisequential Evaporation COde). We examine the evolution of the calculated final mass distributions in the decay of a light compound nucleus, as the initial excitation energy increases towards the limits of complete dissociation. Comparisons are made with the predictions of the transition-stage theory, as well as a consistent Weisskopf treatment in which the decay process is described by rate equations for the generation of different fragment species. (author)
Eta-mesic nuclei: past, present, future
Haider, Q
2015-01-01
Eta-mesic nucleus or the quasibound nuclear state of an eta ($\\eta$) meson in a nucleus is caused by strong-interaction force alone. This new type of nuclear species, which extends the landscape of nuclear physics, has been extensively studied since its prediction in 1986. In this paper, we review and analyze in great detail the models of the fundamental $\\eta$--nucleon interaction leading to the formation of an $\\eta$--mesic nucleus, the methods used in calculating the properties of a bound $\\eta$, and the approaches employed in the interpretation of the pertinent experimental data. In view of the successful observation of the $\\eta$--mesic nucleus $^{25}$Mg$_{\\eta}$ and other promising experimental results, future direction in searching for more $\\eta$--mesic nuclei is suggested.
Origin of Low-Lying Enhanced E1 Strength in Rare-Earth Nuclei
Spieker, M.; Pascu, S.; Zilges, A.; Iachello, F.
2015-01-01
The experimental $E1$ strength distribution below 4 MeV in rare-earth nuclei suggests a local breaking of isospin symmetry. In addition to the octupole states, additional $1^-$ states with enhanced E1 strength have been observed in rare-earth nuclei by means of ($\\gamma,\\gamma'$) experiments. By reproducing the experimental results, the spdf interacting boson model calculations provide further evidence for the formation of an $\\alpha$ cluster in medium-mass nuclei and might provide a new unde...
Unresolved issues in the search for eta-mesic nuclei
Kelkar, N G
2015-01-01
Even if the theoretical definition of an unstable state is straightforward, its experimental identification often depends on the method used in the analysis and extraction of data. A good example is the case of eta mesic nuclei where strong hints of their existence led to about three decades of extensive theoretical and experimental searches. Considering the still undecided status of these states and the limitations in the understanding of the eta-nucleon as well as the eta-nucleus interaction, the present article tries to look back at some unresolved problems in the production mechanism and final state interaction of the eta mesons and nuclei. An unconventional perspective which provides a physical insight into the nature of the eta-nucleus interaction is also presented using quantum time concepts.
Low-energy pi pi photoproduction off nuclei
Mühlich, P; Buss, O; Mosel, U
2004-01-01
In the present paper we investigate pi0 pi0 and pi(+/-)pi0 photoproduction off complex nuclei at incident beam energies of 400-460 MeV. Simulations of two pion photoproduction on protons and nuclei are performed by means of a semi-classical BUU transport model including a full coupled-channel treatment of the final state interactions. Elastic scattering of the final state pions with the nucleons in the surrounding nuclear medium is found to yield a downward shift of the pi pi invariant mass distribution. We show that the target mass dependence of the pi0 pi0 invariant mass spectrum as measured by the TAPS collaboration can be explained without introducing medium effects beyond absorption and quasi-elastic scattering of the final state particles. On the other hand, we find considerable discrepancies with the data in the pi(+/-)pi0 channel, which are not understood.
Exotic light nuclei and nuclei in the lead region
International Nuclear Information System (INIS)
Three methods are discussed for modifying, or renormalizing, a truncated nuclear hamiltonian such that the wave functions obtained by diagonalizing this modified or effective hamiltoniandescribe the nucleus as well as possible: deriving the hamiltonian directly from a realistic nucleon-nucleon interaction between free nucleons; parametrizing the hamiltonian in terms of a number of parameters and determining these parameters from a least-squares fit of calculated properties to experimental data; approximating the nucleon-nucleon (NN) interaction between two nucleons in a nucleus by a simple analytic expression. An effective hamiltonian derived following the second method is applied in a theoretical study of exotic nuclei in the region of Z=2-9 and A=4-30 and the problem of the neutron halo in 11Li is discussed. Results of shell-model calculations of 20iPb and nuclei in its neighbourhood are presented in which an effective hamiltonian was employed derived with the last method. The quenching of M1 strength in 208Pb, and the spectroscopic factors measured in proton knock-out reactions could be described quite satisfactory. Finally, a method is presented for deriving the effective hamiltonian directly from the realistic NN interaction with algebraic techniques. (H.W.). 114 refs.; 34 figs.; 12 tabs.; schemes
Samanta, C.; Adhikari, S
2001-01-01
A new mass formula capable of explaining the binding energies of almost all the known isotopes from Li to Bi is prescribed. In addition to identifying the new magic number at neutron number N=16 (Z=7-9), pseudo-magic numbers at N=14 (Z=7-10), Z=14 (N=13-19), and at N=6 (Z=3-8), the formula accounts for the loss of magicity for nuclei with N=8 (Z=4) and N=20 (Z=12-17). The redefinition of the neutron drip line resulting from this formula further allows us to predict the existence of 26O,31F, 3...
Exotic nuclei and Yukawa's forces
Otsuka, Taka; Suzuki, Toshio; Utsuno, Yutaka
2008-01-01
In this plenary talk, we will overview the evolution of the shell structure in stable and exotic nuclei as a new paradigm of nuclear structure physics. This shell evolution is primarily due to the tensor force. The robust mechanism and some examples will be presented. Such examples include the disappearance of existing magic numbers and the appearance of new ones. The nuclear magic numbers have been believed, since Mayer and Jensen, to be constants as 2, 8, 20, 28, 50, …This turned out to be ...
Investigation of Properties of Exotic Nuclei in Non-relativistic and Relativistic Models
Institute of Scientific and Technical Information of China (English)
2001-01-01
Properties of exotic nuclei are described by non-relativistic and relativistic models. The relativistic mean field theory predicts one proton halo in 26,27,28P and two proton halos in 27,28,29S, recently, one proton halo in 26,27,28P has been found experimentally in MSU lab. The relativistic Hartree-Fock theory has been used to investigate the contribution of Fock term and isovector mesons to the properties of exotic nuclei. It turns out that the influence of the Fock term and isovector mesons on the properties of neutron extremely rich nuclei is very different from that of near stable nuclei. Meanwhile, the deformed Hartree-Fock-Bogoliubov theory has been employed to describe the ground state properties of the isotopes for some light nuclei.
Thalamus parcellation using multi-modal feature classification and thalamic nuclei priors
Glaister, Jeffrey; Carass, Aaron; Stough, Joshua V.; Calabresi, Peter A.; Prince, Jerry L.
2016-03-01
Segmentation of the thalamus and thalamic nuclei is useful to quantify volumetric changes from neurodegenerative diseases. Most thalamus segmentation algorithms only use T1-weighted magnetic resonance images and current thalamic parcellation methods require manual interaction. Smaller nuclei, such as the lateral and medial geniculates, are challenging to locate due to their small size. We propose an automated segmentation algorithm using a set of features derived from diffusion tensor image (DTI) and thalamic nuclei location priors. After extracting features, a hierarchical random forest classifier is trained to locate the thalamus. A second random forest classifies thalamus voxels as belonging to one of six thalamic nuclei classes. The proposed algorithm was tested using a leave-one-out cross validation scheme and compared with state-of-the-art algorithms. The proposed algorithm has a higher Dice score compared to other methods for the whole thalamus and several nuclei.
2002-01-01
We propose to study the elastic resonance scattering reactions $^{9}$Li+p and $^{16}$C+p to investigate the energies, spins and parities of the lowest T=2 states in $^{10}$Be and the T=5/2 states in $^{17}$N. These are analogue states of the ground states and first excited states in $^{10}$Li and $^{17}$C.
Nuclei at the limits of particle stability
International Nuclear Information System (INIS)
The properties and synthesis of nuclei at the limits of particle stability are reviewed. Nuclear reactions were induced and studied by means of the 'exotic' nuclear beams, i.e. beams of radioactive drip-line nuclei. The beams are mostly generated in heavy-ion projectile fragmentation. The cases of both neutron-rich and proton-rich nuclei are discussed. (K.A.) 270 refs.; 13 figs.; 1 tab
Thermal instability of cell nuclei
Warmt, Enrico; Kießling, Tobias R.; Stange, Roland; Fritsch, Anatol W.; Zink, Mareike; Käs, Josef A.
2014-07-01
DNA is known to be a mechanically and thermally stable structure. In its double stranded form it is densely packed within the cell nucleus and is thermo-resistant up to 70\\:^\\circ {\\rm{C}}. In contrast, we found a sudden loss of cell nuclei integrity at relatively moderate temperatures ranging from 45 to 55\\:^\\circ {\\rm{C}}. In our study, suspended cells held in an optical double beam trap were heated under controlled conditions while monitoring the nuclear shape. At specific critical temperatures, an irreversible sudden shape transition of the nuclei was observed. These temperature induced transitions differ in abundance and intensity for various normal and cancerous epithelial breast cells, which clearly characterizes different cell types. Our results show that temperatures slightly higher than physiological conditions are able to induce instabilities of nuclear structures, eventually leading to cell death. This is a surprising finding since recent thermorheological cell studies have shown that cells have a lower viscosity and are thus more deformable upon temperature increase. Since the nucleus is tightly coupled to the outer cell shape via the cytoskeleton, the force propagation of nuclear reshaping to the cell membrane was investigated in combination with the application of cytoskeletal drugs.
Selfconsistent calculations for hyperdeformed nuclei
Energy Technology Data Exchange (ETDEWEB)
Molique, H.; Dobaczewski, J.; Dudek, J.; Luo, W.D. [Universite Louis Pasteur, Strasbourg (France)
1996-12-31
Properties of the hyperdeformed nuclei in the A {approximately} 170 mass range are re-examined using the self-consistent Hartree-Fock method with the SOP parametrization. A comparison with the previous predictions that were based on a non-selfconsistent approach is made. The existence of the {open_quotes}hyper-deformed shell closures{close_quotes} at the proton and neutron numbers Z=70 and N=100 and their very weak dependence on the rotational frequency is suggested; the corresponding single-particle energy gaps are predicted to play a role similar to that of the Z=66 and N=86 gaps in the super-deformed nuclei of the A {approximately} 150 mass range. Selfconsistent calculations suggest also that the A {approximately} 170 hyperdeformed structures have neglegible mass asymmetry in their shapes. Very importantly for the experimental studies, both the fission barriers and the {open_quotes}inner{close_quotes} barriers (that separate the hyperdeformed structures from those with smaller deformations) are predicted to be relatively high, up to the factor of {approximately}2 higher than the corresponding ones in the {sup 152}Dy superdeformed nucleus used as a reference.
Three-body halo nuclei in an effective theory framework
International Nuclear Information System (INIS)
The universal properties and structure of halo nuclei composed of two neutrons (2n) and a core are investigated within an effective quantum mechanics framework. We construct an effective interaction potential that exploits the separation of scales in halo nuclei and treat the nucleus as an effective three-body system, which to leading order is described by the large S-wave scattering lengths in the underlying two-body subsystems. The uncertainty from higher orders in the expansion is quantified through theoretical error bands. First, we investigate the possibility to observe excited Efimov states in 2n halo nuclei. Based on the experimental data, 20C is the only halo nucleus candidate to possibly have an Efimov excited state, with an energy less than 7 keV below the scattering threshold. Second, we study the structure of 20C and other 2n halo nuclei. In particular, we calculate their matter density form factors, radii, and two-neutron opening angles. We then make a systematic improvement upon these calculations by extending the effective potential to the next-to-leading order. To this order, we require an additional two-body parameter, which we tune to the effective range of the interaction. In addition to range corrections to the 2n halo nuclei results, we show corrections to the Efimov effect in the three-boson system. Furthermore, we explore universality in the linear range corrections to the Efimov spectrum. Finally, we study the scattering of D0 and D*0 mesons and their antiparticles off the X(3872) in an effective field theory for short-range interactions. We present results for the S-wave scattering amplitude, total interaction cross section and S-wave scattering length. (orig.)
Meson-exchange forces and medium polarization in finite nuclei
International Nuclear Information System (INIS)
A G-matrix, derived from a meson-exchange potential in nuclear matter, is applied to finite, semi-magic nuclei. For the open shell the broken-pair model, which can accomodate many particle levels, is used. The excitations of the closed shell are treated as particle-hole states. Energy spectra and electromagnetic transition densities are calculated for 88Sr and 58Ni. The standard random-phase approximation for finite systems is extended by including the effects of the exchange of the RPA phonons in the residual interaction selfconsistently. It is shown that this particle-hole interaction is strongly energy dependent due to the presence of poles corresponding to 2p-2h (and more complex) excitations. The RPA eigenvalue problem with this energy-dependent residual interaction also provides solutions for these predominantly 2p2h-like states. In addition a modified normalization condition is obtained. This scheme is applied to 56Ni(56Co) in a large configuration space using a residual interaction of the G-matrix type. The effect of dynamic medium polarization on the properties of giant resonances is illustrated for the case of A=48 nuclei. A large fragmentation of the monopole strength is calculated, which is in accordance with the non-observation of the GMR in light nuclei. Properties of A=48 nuclei are computed with an interaction deduced from the NN scattering data without introduction of additional parameters. The role of medium polarization is illustrated for spectra and (e,e') form factors. It is shown how medium polarization induces a coupling between excitations in even-even and in the adjacent odd-odd nuclei. (Auth.)
Three-body halo nuclei in an effective theory framework
Energy Technology Data Exchange (ETDEWEB)
Canham, David L.
2009-05-20
The universal properties and structure of halo nuclei composed of two neutrons (2n) and a core are investigated within an effective quantum mechanics framework. We construct an effective interaction potential that exploits the separation of scales in halo nuclei and treat the nucleus as an effective three-body system, which to leading order is described by the large S-wave scattering lengths in the underlying two-body subsystems. The uncertainty from higher orders in the expansion is quantified through theoretical error bands. First, we investigate the possibility to observe excited Efimov states in 2n halo nuclei. Based on the experimental data, {sup 20}C is the only halo nucleus candidate to possibly have an Efimov excited state, with an energy less than 7 keV below the scattering threshold. Second, we study the structure of {sup 20}C and other 2n halo nuclei. In particular, we calculate their matter density form factors, radii, and two-neutron opening angles. We then make a systematic improvement upon these calculations by extending the effective potential to the next-to-leading order. To this order, we require an additional two-body parameter, which we tune to the effective range of the interaction. In addition to range corrections to the 2n halo nuclei results, we show corrections to the Efimov effect in the three-boson system. Furthermore, we explore universality in the linear range corrections to the Efimov spectrum. Finally, we study the scattering of D{sup 0} and D{sup *0} mesons and their antiparticles off the X(3872) in an effective field theory for short-range interactions. We present results for the S-wave scattering amplitude, total interaction cross section and S-wave scattering length. (orig.)
Two-body and three-body halo nuclei
Institute of Scientific and Technical Information of China (English)
刘祖华; 张焕乔
2003-01-01
We have extracted the nuclear asymptotic normalization coefficients (ANC) for the virtual transitions B→A+N via some transfer reactions and the radioactive nuclear beam experiments. With these coefficients, root-mean-square (rms) radii for the valence particle in some possible halo nuclei have been calculated. The values of rms radii extracted with ANC approach are nearly model-independent, hence are a good quantity for the investigation of nuclear halo. In addition, we have also calculated the rms radii for the two valence neutrons in some three-body systems in terms of the relationship between the radii of valence particle, core nucleus and nuclear matter. With two conditions for nuclear halo formation, we have examined these extracted rms radii. The results show that 11Be(1/2+, g.s), 12B(1-, 2.621 MeV), 13C(1/2+, 3.089 MeV), 14C(0-, 6.903 MeV), 14C(1-, 6.094 MeV), 15C(1/2+, g.s) and 19C(1/2+, g.s) with the valence particle in the 2s ground or excited state are the neutron halo nuclei, whereas 17F(1/2+, 0.495 MeV) and 21Na(1/2+, 2.423 MeV) are the proton halo nuclei in the excited state. For three-body systems, except the well-established two-neutron halo nuclei 6He and 11Li, 14Be and 17B might be the two-neutron halo nuclei as well.
Dynamical effects in fusion with exotic nuclei
Vo-Phuoc, K.; Simenel, C.; Simpson, E. C.
2016-08-01
Background: Reactions with stable beams have demonstrated strong interplay between nuclear structure and fusion. Exotic beam facilities open new perspectives to understand the impact of neutron skin, large isospin, and weak binding energies on fusion. Microscopic theories of fusion are required to guide future experiments. Purpose: To investigate new effects of exotic structures and dynamics in near-barrier fusion with exotic nuclei. Method: Microscopic approaches based on the Hartree-Fock (HF) mean-field theory are used for studying fusion barriers in -54Ca40+116Sn reactions for even isotopes. Bare potential barriers are obtained assuming frozen HF ground-state densities. Dynamical effects on the barrier are accounted for in time-dependent Hartree-Fock (TDHF) calculations of the collisions. Vibrational couplings are studied in the coupled-channel framework and near-barrier nucleon transfer is investigated with TDHF calculations. Results: The development of a neutron skin in exotic calcium isotopes strongly lowers the bare potential barrier. However, this static effect is not apparent when dynamical effects are included. On the contrary, a fusion hindrance is observed in TDHF calculations with the most neutron-rich calcium isotopes which cannot be explained by vibrational couplings. Transfer reactions are also important in these systems due to charge equilibration processes. Conclusions: Despite its impact on the bare potential, the neutron skin is not seen as playing an important role in the fusion dynamics. However, the charge transfer with exotic projectiles could lead to an increase of the Coulomb repulsion between the fragments, suppressing fusion. The effects of transfer and dissipative mechanisms on fusion with exotic nuclei deserve further studies.
Microscopic description of α-decay from superdeformed nuclei
International Nuclear Information System (INIS)
Superdeformed nuclei have been intensively investigated, both experimentally and theoretically, during the last decade. We have studied in this paper alpha decay from superdeformed nuclei. For this we have solved exactly the problem of penetration of the alpha particle through a deformed barrier. We have found that approximate treatments of the penetrability in terms of the deformation, as e. g. the WKB approximation or the classical treatment, are not valid for deformations larger than β2∼ 0.3. We have also presented a formalism to calculate the formation amplitude of alpha particles in superdeformed nuclei, a number which is necessary in evaluating the absolute decay widths. Since this calculation requires the use of single-particle states that can describe processes occurring outside the nuclear surface, we introduced a representation consisting of the eigenvalues of two different harmonic oscillator potentials. The low lying members of the representation correspond to the standard single-particle states used to describe bound properties, while the high lying members correspond to the eigenvalues of a shallow harmonic oscillator potential. Within this representation we used the HFB approximation to describe the structure of the superdeformed nuclei. This single-particle basis allows for a much faster convergency of the computed formation amplitude in the region beyond the nuclear surface, where the interaction becomes practically a Coulomb repulsion between the emitted alpha particle and the daughter nucleus. We can therefore perform calculations which would otherwise be prohibitive. We have thus found that the formation amplitude (and the corresponding alpha decay probability) decreases with the difference between the quadrupole deformations in the mother and daughter nuclei, although this is not a big effect. We assumed that the mother nucleus decays by electromagnetic transitions to the head of a superdeformed band. From here we considered that alpha decay
Structure of light neutron-rich nuclei through Coulomb dissociation
Indian Academy of Sciences (India)
U Datta Pramanik; T Aumann; D Cortina; H Emling; H Geissel; M Hellström; R Holzmann; N Iwasa; Y Leifels; G Münzenberg; M Rejmund; C Scheidenberger; K Sümmerer; A Leistenschneider; Th W Elze; A Grünschloss; S Ilievski; K Boretzky; J V Kratz; R Kulessa; E Lubkiewicz; E Wajda; W Walus; P Reiter; H Simon
2001-08-01
Coulomb breakup of neutron-rich nuclei around mass ∼ 20 has been studied experimentally using secondary beams (∼ 500–600 MeV/u) of unstable nuclei produced at GSI. The spectroscopic factor deduced for the neutron occupying 1/2 level in 15C ground state is consistent with the earlier reported value. The data analysis for Coulomb breakup of 17C shows that most of the cross section yields the 16C core in its excited state. For 17-22O, the low-lying E1 strength amounts up to about 12% of the energy weighted dipole sum rule strength depending on neutron excess. The cluster sum rule limit with 16O as a core is almost exhausted for 17,18O, while for more neutron rich isotopes the strength with respect to that limit decreases.
Gamow-Teller decay of T = 1 nuclei to odd-odd N = Z nuclei
Energy Technology Data Exchange (ETDEWEB)
Lisetskiy, A F [National Superconducting Cyclotron Laboratory, MSU, East Lansing, MI 48824 (United States); Gelberg, A [Institute for Nuclear Physics, University of Cologne, 50937 Cologne (Germany); Institute of Physical and Chemical Reasearch (RIKEN), Wako, 351-0198 (Japan); Brentano, P von [Institute for Nuclear Physics, University of Cologne, 50937 Cologne (Germany)
2005-01-01
Transition strengths of Gamow-Teller decay of T{sub z} = {+-}1 nuclei to N = Z odd-odd nuclei have been calculated in a two-nucleon approximation for spherical and deformed nuclei. The results obtained for the latter are quite close to the values obtained by full-space shell-model calculations and to the experiment.
Electromagnetic Transition Strengths for Light Nuclei in the Skyrme model
Haberichter, M; Manton, N S
2015-01-01
We calculate reduced $B(E2)$ electromagnetic transition strengths for light nuclei of mass numbers $B=8,12,16,20,24$ and $32$ within the Skyrme model. We find that the predicted transition strengths are of the correct order of magnitude and the computed intrinsic quadrupole moments match the experimentally observed effective nuclear shapes. For the Hoyle state we predict a large $B(E2)\\!\\uparrow$ value of $0.0521\\, \\rm{e}^2\\rm{b}^2$. For Oxygen-16, we can obtain a quantitative understanding of the ground state rotational band and the rotational excitations of the second spin-0 state, $0_2^+$.
Formation of $\\phi$ mesic nuclei
Yamagata-Sekihara, J; Vacas, M J Vicente; Hirenzaki, S
2010-01-01
We study the structure and formation of the $\\phi$ mesic nuclei to investigate the in-medium modification of the $\\phi$-meson spectral function at finite density. We consider (${\\bar p},\\phi$), ($\\gamma,p$) and ($\\pi^-,n$) reactions to produce a $\\phi$-meson inside the nucleus and evaluate the effects of its medium modifications to the reaction cross sections. We also estimate the consequences of the uncertainties of the ${\\bar K}$ selfenergy in medium to the $\\phi$-nucleus interaction. We find that it may be possible to see a peak structure in the reaction spectra for the strong attractive potential cases. On the other hand, for strong absorptive interaction cases with relatively weak attractions, it is very difficult to observe clear peaks and we may need to know the spectrum shape in a wide energy region to deduce the properties of $\\phi$.
Inclusive breakup of Borromean nuclei
Hussein, Mahir S; Frederico, Tobias
2016-01-01
We derive the inclusive breakup cross section of a three-fragment projectile nuclei, $a = b +x_1 + x_2$, in the spectator model. The resulting four-body cross section for observing $b$, is composed of the elastic breakup cross section which contains information about the correlation between the two participant fragments, and the inclusive non-elastic breakup cross section. This latter cross section is found to be a non-trivial four-body generalization of the Austern formula \\cite{Austern1987}, which is proportional to a matrix element of the form, $\\langle\\hat{\\rho}_{{x_1},{x_2}}\\left|\\left[W_{{x_1}} + W_{{x_2}} + W_{3B}\\right]\\right|\\hat{\\rho}_{{x_1}, {x_2}}\\rangle$. The new feature here is the three-body absorption, represented by the imaginary potential, $W_{3B}$. We analyze this type of absorption and supply ideas of how to calculate its contribution.
CAVITATION NUCLEI: EXPERIMENTS AND THEORY
Institute of Scientific and Technical Information of China (English)
MфRCH K. A.
2009-01-01
The Swedish astrophysicist and Nobel Prize winner Hannes Alfvén said: Theories come and go ─ the experiment is here forever. Often a theory, which we set up to describe an observed physical phenomenon, suffers from the lack of knowledge of decisive parameters, and therefore at best the theory becomes insufficient. Contrary, the experiment always reveals nature itself, though at prevailing experimental conditions. With essential parameters being out of control and even maybe unidentified, apparently similar experiments may deviate way beyond our expectations. However, these discrepancies offer us a chance to reflect on the character of the unknown parameters. In this way non-concordant experimental results may hold the key to the development of better theories – and to new experiments for the testing of their validity. Cavitation and cavitation nuclei are phenomena of that character.
Alternative method for evaluating the pair energy of nucleons in nuclei
Energy Technology Data Exchange (ETDEWEB)
Nurmukhamedov, A. M., E-mail: fattah52@mail.ru [Tashkent Pediatric Medical Institute (Uzbekistan)
2015-12-15
An alternative method for determining the odd–even effect parameter related to special features of the Casimir operator in Wigner’s mass formula for nuclei is proposed. A procedure for calculating this parameter is presented. The proposed method relies on a geometric interpretation of the Casimir operator, experimental data concerning the contribution of spin–orbit interaction to the nuclear mass for even–even and odd–odd nuclei, and systematics of energy gaps in the spectra of excited states of even–even nuclei.
Low-lying levels in the nuclei /sup 151/Nd and /sup 155/Sm
Energy Technology Data Exchange (ETDEWEB)
Katajanheimo, R.; Jaderholm, R.; Siivola, A.; Tuurnala, T.; Hammaren, E.; Liukkonen, E.
1984-05-01
Decay properties of excited states in the /sup 151/Nd and /sup 155/Sm nuclei produced by 10 MeV deuterons have been investigated with in-beam gamma-gamma-coincidence equipment during bombardment of the /sup 150/Nd and /sup 154/Sm targets. The measurements largely confirm the data obtained earlier for these nuclei. The (d, p..gamma..) reaction channel favors population of odd-parity low-spin levels, whose energies follow the rule of regular band structure for well-deformed nuclei. The level schemes are interpreted with calculations using an axial particle-rotor model with a Woods-Saxon potential.
Low-lying levels in the nuclei151Nd and155Sm
Katajanheimo, R.; Jäderholm, R.; Siivola, A.; Tuurnala, T.; Hammarén, E.; Liukkonen, E.
1984-10-01
Decay properties of excited states in the151Nd and155Sm nuclei produced by 10 MeV douterons have been investigated with in-beam gamma-gamma-coincidence equipment during bombardment of the150Nd and154Sm targets. The results largely confirm the data obtained earlier for these nuclei. The ( d, p γ) reaction channel favors population of odd-parity low-spin levels, whose energies follow the rule of regular band structure for well-deformed nuclei. The level schemes are interpreted with calculations using an axial particle-rotor model with a Woods-Saxon potential.
Positron production in collision of heavy nuclei
Khriplovich, I B
2016-01-01
We consider the electromagnetic production of positron in collision of slow heavy nuclei, with the simultaneously produced electron captured by one of the nuclei. The cross-section of the discussed process exceeds essentially the cross-section of $e^+e^-$ production.
Mean-field models and exotic nuclei
Energy Technology Data Exchange (ETDEWEB)
Bender, M.; Buervenich, T.; Maruhn, J.A.; Greiner, W. [Inst. fuer Theoretische Physik, Univ. Frankfurt (Germany); Rutz, K. [Inst. fuer Theoretische Physik, Univ. Frankfurt (Germany)]|[Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Reinhard, P.G. [Inst. fuer Theoretische Physik, Univ. Erlangen (Germany)
1998-06-01
We discuss two widely used nuclear mean-field models, the relativistic mean-field model and the (nonrelativistic) Skyrme-Hartree-Fock model, and their capability to describe exotic nuclei. Test cases are superheavy nuclei and neutron-rich Sn isotopes. New information in this regime helps to fix hitherto loosely determined aspects of the models. (orig.)
Etaprime interactions with nucleons and nuclei
Bass, Steven D
2015-01-01
We summarise recent progress in theory and experiment towards understanding etaprime meson interactions with nucleons and nuclei. Highlights include the production mechanism of etaprime mesons in proton-proton collisions close to threshold, the etaprime effective mass shift in nuclei and the determination of the etaprime-nucleon scattering length in free space.
RFP for the Comet Nuclei Tour (CONTOUR)
DEFF Research Database (Denmark)
Jørgensen, John Leif; Madsen, Peter Buch; Betto, Maurizio;
1999-01-01
This document describes the ASC Star Tracker (performance, functionality, requirements etc.) to The Johns Hopkins University - Applied Physics Laboratory for their Comet Nuclei TOUR (CONTOUR) Program.......This document describes the ASC Star Tracker (performance, functionality, requirements etc.) to The Johns Hopkins University - Applied Physics Laboratory for their Comet Nuclei TOUR (CONTOUR) Program....
Variation of hadron masses in finite nuclei
Saitô, K; Tsushima, K; Saito, Koichi; Thomas, Anthony W.; Tsushima, Kazuo
1997-01-01
Using a self-consistent, Hartree description for both infinite nuclear matter and finite nuclei based on a relativistic quark model (the quark-meson coupling model), we investigate the variation of the masses of the non-strange vector mesons, the hyperons and the nucleon in infinite nuclear matter and in finite nuclei.
Partial dynamical symmetry in deformed nuclei
Leviatan, A
1996-01-01
We discuss the notion of partial dynamical symmetry in relation to nuclear spectroscopy. Explicit forms of Hamiltonians with partial SU(3) symmetry are presented in the framework of the interacting boson model of nuclei. An analysis of the resulting spectrum and electromagnetic transitions demonstrates the relevance of such partial symmetry to the spectroscopy of axially deformed nuclei.
Energy Radiation of the Active Galactic Nuclei
Institute of Scientific and Technical Information of China (English)
TANG Zhi-Ming; WANG Yong-Jiu
2004-01-01
In the Hellings-Nordtvedt theory, we obtain some expressions of energy radiation and mass defect effect for a kind of the active galactic nuclei, which is meaningful to calculating the energy radiation in the procession of forming this kind of celestial bodies. This calculation can give some interpretation for energy source of the jet from the active galactic nuclei.
Properties of fission fragments for Z =112 -116 superheavy nuclei
Kaur, Gurjit; Sandhu, Kirandeep; Sharma, Manoj K.
2016-07-01
The dynamical cluster decay model (DCM) is applied to understand the dynamics of 48Ca+238U,244Pu,248Cm reactions at comparable excitation energies across the barrier. To understand the capture stage of *286112 ,*292114 , and *296116 nuclei, the compound nucleus formation probability is calculated. The indication of PC Nprocess such as quasifission may occur at the capture stage of the 48Ca induced reactions. To understand this further, the comparative decay analysis of *286112 ,*292114 and *296116 , nuclei is carried out using β2 i deformations within hot optimum orientation criteria, and the calculated fission cross sections find nice agreement with available data. The fission mass distribution shows a double humped structure where a symmetric peak observed around the Sn region appears to find its genesis in a symmetric quasifission component. On the other hand, the emergence of peaks around Pb in the decay of Z =112 , 114, and 116 nuclei signify the possible presence of asymmetric quasifission. Higher and broader asymmetric quasifission peaks are observed for *296116 and *292114 nuclei as compared to *286112 nucleus. Beside this, the total kinetic energy (TKE) distribution of the decay fragments is also explored by using different proximity potentials, such as Prox-77, Prox-88, and Prox-00. Prox-88 seems to perform better and the calculated TKE values find relatively better comparison at lower angular momentum states. The possible role of different radii of the decaying nuclei is also exercised to understand the TKE ¯ dynamics of 48Ca+238U,244Pu,248Cm reactions.
Microscopic study of muon-capture transitions in nuclei involved in double-beta-decay processes
Kortelainen, M
2003-01-01
Total and partial ordinary muon-capture (OMC) rates to 1 sup + and 2 sup - states are calculated in the framework of the proton-neutron quasiparticle random-phase approximation (pnQRPA) for several nuclei involved in double-beta-decay processes. The aim is to obtain information on intermediate states involved in double-beta-decay transitions having these nuclei as either daughter or parent nuclei. It is found that the OMC observables, just like the 2 nu beta beta-decay amplitudes, strongly depend on the particle-particle part of the proton-neutron interaction. First experiments measuring the partial OMC rates for nuclei involved in double beta decays have recently been performed.
The Northwest Frontier: Spectroscopy of N sim Z Nuclei Below Mass 100
Wadsworth, R.; Nara Singh, B. S.; Steer, A. N.; Jenkins, D. G.; Bentley, M. A.; Brock, T.; Davies, P.; Glover, R.; Pattabiraman, N. S.; Scholey, C.; Grahn, T.; Greenlees, P. T.; Jones, P.; Jakobsson, U.; Julin, R.; Juutinen, S.; Ketelhut, S.; Leino, M.; Nyman, M.; Perua, P.; Pakarinen, J.; Rahkila, P.; Ruotslainen, P.; Sorri, J.; Uusitalo, J.; Lister, C. J.; Butler, P. A.; Dimmock, M.; Joss, D. T.; Thomson, J.; Rinta-Antila, S.; Cederwall, B.; Hadinia, B.; Sandzelius, M.; Atac, A.; Betterman, L.; Blazhev, A.; Braun, N.; Finke, F.; Geibel, K.; Ilie, G.; Iwasaki, H.; Jolie, J.; Reiter, P.; Scholl, C.; Warr, N.; Boutachkov, P.; Caceres, L.; Domingo, C.; Engert, T.; Farinon, F.; Gerl, J.; Goel, N.; Gorska, M.; Grawe, H.; Kurz, N.; Kojuharov, I.; Pietri, S.; Nociforo, C.; Prochazka, A.; Wollersheim, H.-J.; Eppinger, K.; Faestermann, T.; Hinke, C.; Hoischen, R.; Kruecken, R.; Gottardo, A.; Liu, Z.; Woods, P.; Grebosz, J.; Merchant, E.; Nyberg, J.; Soderstrom, P.-A.; Podolyak, Z.; Regan, P.; Steer, S.; Pfutzner, M.; Rudolph, D.
2009-03-01
The spectroscopy and structure of excited states of N sim Z nuclei in the mass 70-100 region has been investigated using two techniques. In the A sim 70-80 region fusion evaporation reactions coupled with the recoil- beta -tagging method have been employed at Jyvaskyla to study low-lying states in odd-odd N = Z nuclei. Results from these and other data for known odd-odd nuclei above mass 60 will be discussed. In the heavier mass 90 region a fragmentation experiment has been performed using the RISING/FRS setup at GSI. This experiment was primarily aimed at searching for spin gap isomers in nuclei around A sim 96. The objectives of the latter experiment will be discussed.
Total Nuclear Reaction Cross Section Induced by Halo Nuclei and Stable Nuclei
Institute of Scientific and Technical Information of China (English)
GUO Wen-Jun; JIANG Huan-Qing; LIU Jian-Ye; ZUO Wei; REN Zhong-Zhou; LEE Xi-Guo
2003-01-01
We develop a method for calculation of the total reaction cross sections induced by the halo nuclei and stable. nuclei. This approach is based on the Glauber theory, which is valid for nuclear reactions at high energies. It is extended for nuclear reactions at low energies and intermediate energies by including both the quantum correction and Coulomb correction under the assumption of the effective nuclear density distribution. The calculated results of the total reaction cross section induced by stable nuclei agree well with 30 experimental data within 10 percent accuracy. The comparison between the numerical results and 20 experimental data for the total nuclear reaction cross section induced by the neutron halo nuclei and the proton halo nuclei indicates a satisfactory agreement after considering the halo structure of these nuclei, which implies quite different mean fields for the nuclear reactions induced by halo nuclei and stable nuclei. The halo nucleon distributions and the root-mean-square radii of these nuclei can be extracted from the above comparison based on the improved Glauber model, which indicates clearly the halo structures of these nuclei. Especially,it is clear to see that the medium correction of the nucleon-nucleon collision has little effect on the total reaction cross sections induced by the halo nuclei due to the very weak binding and the very extended density distribution.
SMMC studies of N=Z pf-shell nuclei with pairing-plus-quadrupole Hamiltonian
Langanke, K.; Vogel, P.; Zheng, Dao-Chen
1997-01-01
We perform Shell Model Monte Carlo calculations of selected N=Z pf-shell nuclei with a schematic hamiltonian containing isovector pairing and quadrupole-quadrupole interactions. Compared to realistic interactions, this hamiltonian does not give rise to the SMMC ``sign problem'', while at the same time resembles essential features of the realistic interactions. We study pairing correlations in the ground states of N=Z nuclei and investigate the thermal dependence of selected observables for th...
Low-energy limit of the radiative dipole strength in nuclei
Litvinova, Elena; Belov, Nikolay
2013-01-01
We explain the low-energy anomaly reported in several experimental studies of the radiative dipole strength functions in medium-mass nuclei. These strength functions at very low gamma-energies correspond to the gamma-transitions between very close nuclear excited states in the quasicontinuum. In terms of the thermal mean-field, the low-energy enhancement of the strength functions in highly-excited compound nuclei is explained by nucleonic transitions from the thermally unblocked single-quasip...
Dynamical symmetries of BEC: exact energy formulas and an application to alpha-conjugate nuclei
International Nuclear Information System (INIS)
An algebraic approach, based on dynamical symmetries, to Bose-Einstein condensates will be illustrated. It allows to write symmetry-dictated exact energy formulas for boson condensates that depend typically on a few quantum numbers. The application to alpha condensation in nuclei will be discussed in detail, showing that symmetry alone is sufficient to predict the energy of N-alpha states in alpha conjugate nuclei. Experiments that might improve the present knowledge will be suggested. (author)
Neutron Skin Thickness of Nuclei and Effective Nucleon-Nucleon Interactions
Institute of Scientific and Technical Information of China (English)
LIU Min; WANG Ning; LI Zhu-Xia; WU Xi-Zhen
2006-01-01
@@ The Skyrme energy density functional is applied to study the ground state properties of a series of finite nuclei.The charge rms radii, neutron rms radii, and the neutron skin thickness for some nuclei are calculated and compared with the experimental data. The constraint on the effective interactions, especially, the density dependence of the isospin-dependent part of Skyrme interactions is extracted by the data of neutron skin thicknesses of 208 pb and isotopes of Sn.
Structure Shape Evolution in Lanthanide and Actinide Nuclei
Directory of Open Access Journals (Sweden)
Khalaf A. M.
2013-04-01
Full Text Available To give the characteristics of the evolution of the collectivity in even-even nuclei, we studied the behavior of the energy ratios R(4 / 2 and R(6 / 4. All chains of lanthanides begins as vibrational with R(4 / 2 near 2.0 and move towards rotational (R(4 / 2 3.33 as neutron number increases. A rabid jump in R(4 / 2 near N = 90 was seen. The plot of R(4 / 2 against Z shows not only the existence of a shape transitions but also the change in curvature in the data for N = 88 and 90, concave to convex. For intermedi- ate structure the slopes in E-GOS ( E over spin plots range between the vibrator and rotor extremes. The abnormal behavior of the two-neutron separation energies of our lanthanide nuclei as a function of neutron number around neutron number 90 is cal- culated. Nonlinear behavior is observed which indicate that shape phase transition is occurred in this region. The calculated reduced B(E2 transition probabilities of the low states of the ground state band in the nuclei 150 Nd / 152 Sm / 154 Gd / 156 Dy are analyzed and compared to the prediction of vibrational U(5 and rotational SU(3 limits of interacting boson model calculations.
Study of high angular momentum phenomena in rotating nuclei
International Nuclear Information System (INIS)
Information about rotational bands of deformed Yb nuclei as obtained through in-beam spectroscopic studies is discussed. Routhians and alignments have been extracted from the experimental data. Experimental single-quasineutron routhians have been used to construct two- and three-quasineutron routhians. Residual interaction between excited quasiparticles is obtained from a comparison of the excitation energies of multiple-quasiparticle states constructed from single-quasiparticle states. An odd-even neutron-number dependence of the alignment frequency of the first pair of isub(13/2) quasineutron in rare-earth nuclei is presented. This effect is explained by a reduction of the neutron pairing-correlation parameter for odd-N systems as compared to seniority-zero configurations in even-N nuclei. The signature dependence of the interband-intraband branching ratios as well as of the interband M1/E2 mixing ratios is discussed and compared to the signature dependence of B(M1) transition rates recently suggested by Hamamoto. (author)
Description of radiative strength functions of deformed nuclei
International Nuclear Information System (INIS)
Radiative strength functions of E1R- and M1-transitions from ground states of doubly even deformed nuclei to states near the neutron binding energy Bsub(n), the wave functions of which include one- and two-phonon components, are calculated within the quasiparticle-phonon nuclear model. The calculations were made with the Pauli principle being or not included in the two-phonon components of the wave functions. It is shown that the radiative E1R- and M1-strength functions as well as the widths of giant dipole resonances in deformed nuclei are slightly influenced by the two-phonon components of the wave functions and they can be calculated in the random phase approximation. The ksub(E1) and ksub(M1)-values are calculated for some deformed nuclei of the rare-earth and actinide region. The calculated values of ksub(E1) are 1.5-2 times larger and the values of ksub(M1) are somewhat less than the average values obtained from the analysis of available experimental data
Fusion probability in heavy nuclei
Banerjee, Tathagata; Nath, S.; Pal, Santanu
2015-03-01
Background: Fusion between two massive nuclei is a very complex process and is characterized by three stages: (a) capture inside the potential barrier, (b) formation of an equilibrated compound nucleus (CN), and (c) statistical decay of the CN leading to a cold evaporation residue (ER) or fission. The second stage is the least understood of the three and is the most crucial in predicting yield of superheavy elements (SHE) formed in complete fusion reactions. Purpose: A systematic study of average fusion probability, PCN> , is undertaken to obtain a better understanding of its dependence on various reaction parameters. The study may also help to clearly demarcate onset of non-CN fission (NCNF), which causes fusion probability, PCN, to deviate from unity. Method: ER excitation functions for 52 reactions leading to CN in the mass region 170-220, which are available in the literature, have been compared with statistical model (SM) calculations. Capture cross sections have been obtained from a coupled-channels code. In the SM, shell corrections in both the level density and the fission barrier have been included. PCN> for these reactions has been extracted by comparing experimental and theoretical ER excitation functions in the energy range ˜5 %-35% above the potential barrier, where known effects of nuclear structure are insignificant. Results: PCN> has been shown to vary with entrance channel mass asymmetry, η (or charge product, ZpZt ), as well as with fissility of the CN, χCN. No parameter has been found to be adequate as a single scaling variable to determine PCN> . Approximate boundaries have been obtained from where PCN> starts deviating from unity. Conclusions: This study quite clearly reveals the limits of applicability of the SM in interpreting experimental observables from fusion reactions involving two massive nuclei. Deviation of PCN> from unity marks the beginning of the domain of dynamical models of fusion. Availability of precise ER cross sections
International Nuclear Information System (INIS)
Magnetic rotation is a new phenomenon that is forcing physicists to rethink their understanding of what goes on inside the nucleus The rotation of quantum objects has a long and distinguished history in physics. In 1912 the Danish scientist Niels Bjerrum was the first to recognize that the rotation of molecules is quantized. In 1938 Edward Teller and John Wheeler observed similar features in the spectra of excited nuclei, and suggested that this was caused by the nucleus rotating. But a more complete explanation had to wait until 1951, when Aage Bohr (the son of Niels) pointed out that rotation was a consequence of the nucleus deforming from its spherical shape. We owe much of our current understanding of nuclear rotation to the work of Bohr and Ben Mottelson, who shared the 1975 Nobel Prize for Physics with James Rainwater for developing a model of the nucleus that combined the individual and collective motions of the neutrons and protons inside the nucleus. What makes it possible for a nucleus to rotate? Quantum mechanically, a perfect sphere cannot rotate because it appears the same when viewed from any direction and there is no point of reference against which its change in position can be detected. To see the rotation the spherical symmetry must be broken to allow an orientation in space to be defined. For example, a diatomic molecule, which has a dumbbell shape, can rotate about the two axes perpendicular to its axis of symmetry. A quantum mechanical treatment of a diatomic molecule leads to a very simple relationship between rotational energy, E, and angular momentum. This energy is found to be proportional to J(J + 1), where J is the angular momentum quantum number. The molecule also has a magnetic moment that is proportional to J. These concepts can be applied to the atomic nucleus. If the distribution of mass and/or charge inside the nucleus becomes non-spherical then the nucleus will be able to rotate. The rotation is termed ''collective'' because many
Nuclear magnetic and quadrupole moments for nuclear structure research on exotic nuclei
Neyens, G
2003-01-01
One of the key issues in current nuclear physics research is to investigate the properties of so-called 'exotic nuclei' and of 'exotic nuclear structures'. Exotic nuclei are nuclei with a proton-to-neutron ratio that is very different from the proton-to-neutron ratio in stable nuclei (a technical term related to this ratio is the 'isospin'). We define exotic nuclear structures as excitation modes of nuclei that have a very different structure than the structure (or shape) of the nuclear ground state. By putting the nucleons in a nucleus to extreme conditions of isospin and excitation energy one can investigate details of one of the four basic forces in nature: the strong force which binds the nucleons together to form a bound nucleus. While the basic properties of the strong nucleon-nucleon interaction are known from investigating the properties of nuclei near the 'valley of stability', recent developments in the study of exotic nuclei have demonstrated that specific properties of the strong interaction, such...
Lattice Effective Field Theory for Medium-Mass Nuclei
Lähde, Timo A; Krebs, Hermann; Lee, Dean; Meißner, Ulf-G; Rupak, Gautam
2014-01-01
We extend Nuclear Lattice Effective Field Theory (NLEFT) to the regime of medium-mass nuclei, and describe a method which allows us to greatly decrease the uncertainties due to extrapolation at large Euclidean time. We present results for the ground states of alpha nuclei from $^4$He to $^{28}$Si, calculated up to next-to-next-to-leading order (NNLO) in the EFT expansion. We discuss systematic errors associated with the momentum-cutoff scale and the truncation of the EFT expansion. While the long-term objectives of NLEFT are a decrease in the lattice spacing and the inclusion of higher-order contributions, we show that the missing physics at NNLO can be approximated by an effective four-nucleon interaction.
Ab Initio Calculations Of Nuclear Reactions And Exotic Nuclei
Energy Technology Data Exchange (ETDEWEB)
Quaglioni, S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
2014-05-05
Our ultimate goal is to develop a fundamental theory and efficient computational tools to describe dynamic processes between nuclei and to use such tools toward supporting several DOE milestones by: 1) performing predictive calculations of difficult-to-measure landmark reactions for nuclear astrophysics, such as those driving the neutrino signature of our sun; 2) improving our understanding of the structure of nuclei near the neutron drip line, which will be the focus of the DOE’s Facility for Rare Isotope Beams (FRIB) being constructed at Michigan State University; but also 3) helping to reveal the true nature of the nuclear force. Furthermore, these theoretical developments will support plasma diagnostic efforts at facilities dedicated to the development of terrestrial fusion energy.
Linking partial and quasi dynamical symmetries in rotational nuclei
Kremer, C; Leviatan, A; Pietralla, N; Rainovski, G; Trippel, R; Van Isacker, P
2014-01-01
Background: Quasi dynamical symmetries (QDS) and partial dynamical symmetries (PDS) play an important role in the understanding of complex systems. Up to now these symmetry concepts have been considered to be unrelated. Purpose: Establish a link between PDS and QDS and find an emperical manifestation. Methods: Quantum number fluctuations and the intrinsic state formalism are used within the framework of the interacting boson model of nuclei. Results: A previously unrecognized region of the parameter space of the interacting boson model that has both O(6) PDS (purity) and SU(3) QDS (coherence) in the ground band is established. Many rare-earth nuclei approximately satisfying both symmetry requirements are identified. Conclusions: PDS are more abundant than previously recognized and can lead to a QDS of an incompatible symmetry.
Ab Initio Calculations Of Nuclear Reactions And Exotic Nuclei
International Nuclear Information System (INIS)
Our ultimate goal is to develop a fundamental theory and efficient computational tools to describe dynamic processes between nuclei and to use such tools toward supporting several DOE milestones by: 1) performing predictive calculations of difficult-to-measure landmark reactions for nuclear astrophysics, such as those driving the neutrino signature of our sun; 2) improving our understanding of the structure of nuclei near the neutron drip line, which will be the focus of the DOE's Facility for Rare Isotope Beams (FRIB) being constructed at Michigan State University; but also 3) helping to reveal the true nature of the nuclear force. Furthermore, these theoretical developments will support plasma diagnostic efforts at facilities dedicated to the development of terrestrial fusion energy.
Study of transitional nuclei at TRISTAN. Progress report
International Nuclear Information System (INIS)
During the past calendar year the Oklahoma group has participated in decay studies on the following nuclides: 99Rb, 99Sr, 101Y, and 100Y. The resulting information on the structure of these nuclides has defined band structure for the first time in the odd-A nuclei in this region. The principal investigator also participated in a measurement of the g-factor of an excited state in 97Zr and two attempts to measure the quadrupole moment of the same state. Details of these and other activities are given
Magnetic hyperfine fields on 119Sn nuclei in uranium compounds
International Nuclear Information System (INIS)
119Sn Moessbauer spectroscopy studies were performed on 12 uranium intermetallic compounds in order to investigate correlations between the formation of the magnetic moment on the U atom and the magnetic hyperfine field transferred to 119Sn nuclei in magnetically ordered materials. The measured hyperfine fields (Hhf) are related to the values of the ordered U magnetic moments (μB) by μoHhf/n=A μU. The parameter A varies between 0.73 (UGa2) and 1.55 (UGe2). It seems to correlate with the extent of the hybridization of the 5f states with the conduction electron states. (orig.)
Molecular outflows in starburst nuclei
Roy, Arpita; Nath, Biman B.; Sharma, Prateek; Shchekinov, Yuri
2016-08-01
Recent observations have detected molecular outflows in a few nearby starburst nuclei. We discuss the physical processes at work in such an environment in order to outline a scenario that can explain the observed parameters of the phenomenon, such as the molecular mass, speed and size of the outflows. We show that outflows triggered by OB associations, with NOB ≥ 105 (corresponding to a star formation rate (SFR)≥1 M⊙ yr-1 in the nuclear region), in a stratified disk with mid-plane density n0 ˜ 200-1000 cm-3 and scale height z0 ≥ 200(n0/102 cm-3)-3/5 pc, can form molecules in a cool dense and expanding shell. The associated molecular mass is ≥107 M⊙ at a distance of a few hundred pc, with a speed of several tens of km s-1. We show that a SFR surface density of 10 ≤ ΣSFR ≤ 50 M⊙ yr-1 kpc-2 favours the production of molecular outflows, consistent with observed values.
Molecular outflows in starburst nuclei
Roy, Arpita; Sharma, Prateek; Shchekinov, Yuri
2016-01-01
Recent observations have detected molecular outflows in a few nearby starburst nuclei. We discuss the physical processes at work in such an environment in order to outline a scenario that can explain the observed parameters of the phenomenon, such as the molecular mass, speed and size of the outflows. We show that outflows triggered by OB associations, with $N_{OB}\\ge 10^5$ (corresponding to a star formation rate (SFR)$\\ge 1$ M$_{\\odot}$ yr$^{-1}$ in the nuclear region), in a stratified disk with mid-plane density $n_0\\sim 200\\hbox{--}1000$ cm$^{-3}$ and scale height $z_0\\ge 200 (n_0/10^2 \\, {\\rm cm}^{-3})^{-3/5}$ pc, can form molecules in a cool dense and expanding shell. The associated molecular mass is $\\ge 10^7$ M$_\\odot$ at a distance of a few hundred pc, with a speed of several tens of km s$^{-1}$. We show that a SFR surface density of $10 \\le \\Sigma_{SFR} \\le 50$ M$_\\odot$ yr$^{-1}$ kpc$^{-2}$ favours the production of molecular outflows, consistent with observed values.
Exotic nuclei far from the stability line
Hagino, K; Sagawa, H
2012-01-01
The recent availability of radioactive beams has opened up a new era in nuclear physics. The interactions and structure of exotic nuclei close to the drip lines have been studied extensively world wide, and it has been revealed that unstable nuclei, having weakly bound nucleons, exhibit characteristic features such as a halo structure and a soft dipole excitation. We here review the developments of the physics of unstable nuclei in the past few decades. The topics discussed in this Chapter include the halo and skin structures, the Coulomb breakup, the dineutron correlation, the pair transfer reactions, the two-nucleon radioactivity, the appearance of new magic numbers, and the pygmy dipole resonances.
True ternary fission of superheavy nuclei
Zagrebaev, V.I.; A. V. Karpov; Greiner, Walter
2010-01-01
We found that a true ternary fission with formation of a heavy third fragment (a new type of radioactivity) is quite possible for superheavy nuclei due to the strong shell effects leading to a three-body clusterization with the two doubly magic tin-like cores. The simplest way to discover this phenomenon in the decay of excited superheavy nuclei is a detection of two tin-like clusters with appropriate kinematics in low-energy collisions of medium mass nuclei with actinide targets. The three-b...
Warm absorbers in active galactic nuclei
Reynolds, C S; Reynolds, C S; Fabian, A C
1995-01-01
Recent {\\it ASCA} observations confirm the presence of X-ray absorption due to partially ionized gas in many Seyfert 1 galaxies; the so-called warm absorber. Constraints on the location of the warm material are presented with the conclusion that this material lies at radii coincident with, or just outside, the broad-line region. The stability of this warm material to isobaric perturbations under the assumptions of thermal and photoionization equilibrium is also studied. It is shown that there is a remarkably small range of ionization parameter, \\xi, for which the warm absorber state is stable. The robustness of this result to changes in the shape of the primary continuum, the assumed density and optical depth is investigated. Given the constraints on the location and the stability properties of the material, several models for the environments of Seyfert nuclei are discussed. These attempt to explain the presence of significant amounts of partially ionized material. In particular, various models of the broad-...
Isospin symmetry breaking in sd shell nuclei
International Nuclear Information System (INIS)
In the thesis, we develop a microscopic approach to describe the isospin-symmetry breaking effects in sd-shell nuclei. The work is performed within the nuclear shell model. A realistic isospin-conserving Hamiltonian is perfected by a charge-dependent part consisting of the Coulomb interaction and Yukawa-type meson exchange potentials to model charge-dependent forces of nuclear origin. The extended database of the experimental isobaric mass multiplet equation coefficients was compiled during the thesis work and has been used in a fit of the Hamiltonian parameters. The constructed Hamiltonian provides an accurate theoretical description of the isospin mixing nuclear states. A specific behaviour of the IMME (Isobaric Multiplet Mass Equation) coefficients have been revealed. We present two important applications: (i) calculations of isospin-forbidden proton emission amplitudes, which is often of interest for nuclear astrophysics, and (ii) calculation on corrections to nuclear Fermi beta decay, which is crucial for the tests of fundamental symmetries of the weak interaction. (author)
Light nuclei of even mass number in the Skyrme model
Battye, R. A.; Manton, N. S.; Sutcliffe, P. M.; Wood, S. W.
2009-09-01
We consider the semiclassical rigid-body quantization of Skyrmion solutions of mass numbers B=4,6,8,10, and 12. We determine the allowed quantum states for each Skyrmion and find that they often match the observed states of nuclei. The spin and isospin inertia tensors of these Skyrmions are accurately calculated for the first time and are used to determine the excitation energies of the quantum states. We calculate the energy level splittings, using a suitably chosen parameter set for each mass number. We find good qualitative and encouraging quantitative agreement with experiment. In particular, the rotational bands of beryllium-8 and carbon-12, along with isospin 1 triplets and isospin 2 quintets, are especially well reproduced. We also predict the existence of states that have not yet been observed and make predictions for the unknown quantum numbers of some observed states.
Light nuclei of even mass number in the Skyrme model
International Nuclear Information System (INIS)
We consider the semiclassical rigid-body quantization of Skyrmion solutions of mass numbers B=4,6,8,10, and 12. We determine the allowed quantum states for each Skyrmion and find that they often match the observed states of nuclei. The spin and isospin inertia tensors of these Skyrmions are accurately calculated for the first time and are used to determine the excitation energies of the quantum states. We calculate the energy level splittings, using a suitably chosen parameter set for each mass number. We find good qualitative and encouraging quantitative agreement with experiment. In particular, the rotational bands of beryllium-8 and carbon-12, along with isospin 1 triplets and isospin 2 quintets, are especially well reproduced. We also predict the existence of states that have not yet been observed and make predictions for the unknown quantum numbers of some observed states.
Light Nuclei of Even Mass Number in the Skyrme Model
Battye, Richard A; Sutcliffe, Paul M; Wood, Stephen W
2009-01-01
We consider the semiclassical rigid-body quantization of Skyrmion solutions of mass numbers B = 4, 6, 8, 10 and 12. We determine the allowed quantum states for each Skyrmion, and find that they often match the observed states of nuclei. The spin and isospin inertia tensors of these Skyrmions are accurately calculated for the first time, and are used to determine the excitation energies of the quantum states. We calculate the energy level splittings, using a suitably chosen parameter set for each mass number. We find good qualitative and encouraging quantitative agreement with experiment. In particular, the rotational bands of beryllium-8 and carbon-12, along with isospin 1 triplets and isospin 2 quintets, are especially well reproduced. We also predict the existence of states that have not yet been observed, and make predictions for the unknown quantum numbers of some observed states.
Flambaum, V V; Vorov, O K; Flambaum, V V
1994-01-01
Manifestations of P-,T-odd weak interaction between nucleons in nucleus are considered. Renormalization of this interaction due to residual strong interaction is studied. Mean squared matrix elements of P-,T-odd weak interaction between compound states are calculated. Correlators between P-,T-odd and P-odd, T-even weak interaction matrix elements between compound states are considered and estimates for these quantities are obtained.
Study of nuclei with A = 5 on the basis of the unitary scheme model
International Nuclear Information System (INIS)
The total antisymmetric wave functions of the different states of nuclei with A = 5 are calculated by using the basis of the unitary scheme model corresponding to numbers of quanta of excitations N = 1, 2, 3, 4, 5, 6, and 7. The residual interactions used in these calculations are the Gogny et al. potential, the Doma et al. Potential, and an effective interaction which has been used successfully for the nucleus 6Li. The energy matrices for nuclei with A = 5 are diagonalized in terms of the oscillator parameter ℏω, which is varied in order to obtain the best fit to the spectra of these nuclei. The binding energy, the root mean-square radius, and the magnetic dipole moment of 5He are also calculated. Some new levels for these nuclei are obtained. The role of the three-body forces is also investigated for the nucleus 5He. (author)
Investigation of interplay of single particle and collective modes of excitation in sd shell nuclei
International Nuclear Information System (INIS)
Nuclei in the neighborhood of doubly closed 40Ca usually exhibit characteristics of single particle excitations at low energies. However, several nuclei viz., 40Ca and 36Ar in this mass region have also revealed deformed states (even superdeformation) at relatively higher excitation energies. The observed Superdeformed (SD) bands in these α-conjugate nuclei have been explained using complementary descriptions in terms of particle-hole excitations in the shell model, and α-clustering configurations within various cluster models. In 36Ar, 40Ca, the average deformation (β2) of the SD bands generated with (4p-4h) and (8p-8h) excitations in the pf (N=3) shell, are 0.45 and 0.59, respectively. This is similar to the observation in heavier nuclei where the occupation numbers of high-N orbital have been found to characterise SD bands
Comparison between formulas of rotational band for axially symmetric deformed nuclei
Institute of Scientific and Technical Information of China (English)
WU Xi; LEI Yi-An
2008-01-01
The experimental rotational spectra of the deformed nuclei available in even-even and odd-A nuclei in the rare-earth and actinide regions are systematically analyzed with several rotational spectra formulas,including Bohr-Mottelson's I(I+l)-expansion,Harris'w2-expansion,ab and abc formulas.It is shown that the simple 2-parameter ab formula is much better than the widely used 2-parameter Bohr-Mottelson's AB formula and Harris'αβ formula.The available data of the rotational spectra of both ground-state band in even-even nuclei and one-quaasiparticle band in odd-A nuclei can be conveniently and rather accurately reproduced by ab formula and abc formula.The moment of inertia and the variation with rotational frequency of angular momentum can be satisfactorily reproduced by ab and abc formulas.
Studies of the neutron single-particle structure of exotic nuclei at the HRIBF
Energy Technology Data Exchange (ETDEWEB)
Thomas, J.S. [Department of Physics and Astronomy, Rutgers University, New Brunswick, NJ 08903 (United States); Bardayan, D.W. [Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Blackmon, J.C. [Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Cizewski, J.A. [Department of Physics and Astronomy, Rutgers University, New Brunswick, NJ 08903 (United States); Greife, U. [Department of Physics, Colorado School of Mines, Golden, CO 80401 (United States); Gross, C.J. [Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Johnson, M.S. [Department of Physics and Astronomy, Rutgers University, New Brunswick, NJ 08903 (United States); Jones, K.L. [Department of Physics and Astronomy, Rutgers University, New Brunswick, NJ 08903 (United States); Kozub, R.L. [Physics Department, Tennessee Technological University, Cookeville, TN 38505 (United States); Liang, J.F. [Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Livesay, R.J. [Department of Physics, Colorado School of Mines, Golden, CO 80401 (United States); Ma, Z. [Physics Department, University of Tennessee, Knoxville, TN 37996 (United States); Moazen, B.H. [Physics Department, Tennessee Technological University, Cookeville, TN 38505 (United States); Nesaraja, C.D. [Physics Department, Tennessee Technological University, Cookeville, TN 38505 (United States); Shapira, D. [Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Smith, M.S. [Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)
2004-12-27
The study of neutron single-particle strengths in neutron-rich nuclei is of interest for nuclear structure and nuclear astrophysics. The distribution of single-particle strengths constrains the effective Hamiltonian and pairing interactions and determines neutron interaction rates that are crucial for understanding the synthesis of heavy nuclei in supernovae via the rapid neutron capture process. Particularly important are the neutron single-particle levels in nuclei near closed neutron shells. Radioactive ion beams from the Holifield Radioactive Ion Beam Facility have been used to study (d,p) reactions in inverse kinematics in order to probe neutron single-particle states in exotic nuclei. The results of a measurement with a {sup 82}Ge beam will be presented.
Perspectives of production of superheavy nuclei
Adamian, G. G.; Antonenko, N. V.; Bezbakh, A. N.; Sargsyan, V. V.; Scheid, W.
2016-07-01
Possible ways of production of superheavies are discussed. Impact of nuclear structure on the production of superheavy nuclei in complete fusion reactions is discussed. The proton shell closure at Z = 120 is discussed.
GDR in Hot Nuclei: New Measurements
Camera, F.; Kmiecik, M.; Wieland, O.; Benzoni, G.; Bracco, A.; Brambilla, S.; Crespi, F.; Mason, P.; Moroni, A.; Million, B.; Leoni, S.; Maj, A.; Styczen, J.; Brekiesz, M.; Meczynski, W.; Zieblinski, M.; Gramegna, F.; Barlini, S.; Kravchuk, V. L.; Lanchais, A. L.; Mastinu, P. F.; Bruno, M.; D'Agostino, M.; Geraci, E.; Ordine, A.; Casini, G.; Chiari, M.
2005-04-01
The measured properties of the Giant Dipole Resonance in hot rotating nuclei are successfully described with the model of thermal fluctuations, even though there are still some open problems especially at very low (T 2.5MeV) temperatures and missing data in some mass regions. Recent experimental works have addressed more specific problems regarding the nuclear shape and its behaviour in very particular and delimited phase space regions. In this paper will be discussed new exclusive measurements of the GDR γ decay in heavy 216Rn nuclei (where the shape of nuclei surviving fission have been probed) and some preliminary data on the 132Ce nuclei at very high excitation energy.
Critical-Point Structure in Finite Nuclei
Leviatan, A
2006-01-01
Properties of quantum shape-phase transitions in finite nuclei are considered in the framework of the interacting boson model. Special emphasis is paid to the dynamics at the critical-point of a general first-order phase transition.
Systematic study of shell gaps in nuclei
Mo, Qiuhong; Wang, Ning
2014-01-01
The nucleon separation energies and shell gaps in nuclei over the whole nuclear chart are systematically studied with eight global nuclear mass models. For unmeasured neutron-rich and super-heavy regions, the uncertainty of the predictions from these different mass models is still large. The latest version (WS4) of the Weizs\\"acker-Skyrme mass formula, in which the isospin dependence of model parameters is introduced into the macroscopic-microscopic approach inspired by the Skyrme energy-density functional, is found to be the most accurate one in the descriptions of nuclear masses, separation energies and shell gaps. Based on the predicted shell gaps in nuclei, the possible magic numbers in super-heavy nuclei region are investigated. In addition to the shell closures at $N=184, Z=114$, the sub-shell closures at around $N=178, Z=120$ could also play a role for the stability of super-heavy nuclei.
Quark Degrees of Freedom in Finite Nuclei
Tsushima, K; Thomas, A W; Tsushima, Kazuo; Saito, Koichi; Thomas, Anthony W.
1996-01-01
Properties of finite nuclei are investigated based on relativistic Hartree equations which have been derived from a relativistic quark model of the structure of bound nucleons. Nucleons are assumed to interact through the (self-consistent) exchange of scalar ($\\sigma$) and vector ($\\omega$ and and the rms charge radius in $^{40}$Ca. Calculated properties of static, closed-shell nuclei, as well as symmetric nuclear matter are compared with experimental data and with the results of Quantum Hadrodynamics (QHD).
Physics with nuclei at high energies
International Nuclear Information System (INIS)
Physics with nuclei at high energy is not reducible to a superposition of interactions involving individual nucleons; rather, qualitatively new phenomena show up. This is what one concludes from recent data on dilepton production off nuclei and on elastic proton-nucleus scattering. Furthermore, recent analyses of ion collisions at BNL and CERN reveal a number of non-conventional features. The relevant contributions to this Rencontre are summarized here. 37 refs., 16 figs
Synthesis of superheavy nuclei: Obstacles and opportunities
Zagrebaev, V. I.; Karpov, A. V.; Greiner, Walter
2015-01-01
There are only 3 methods for the production of heavy and superheavy (SH) nuclei, namely, fusion reactions, a sequence of neutron capture and beta(-) decay and multinucleon transfer reactions. Low values of the fusion cross sections and very short half-lives of nuclei with Zcold and hot fusion reactions remains unstudied yet. This gap could be filled in fusion reactions of 48Ca with available lighter isotopes of Pu, Am, and Cm. New neutron-enriched isotopes of SH elements may be produced with the use of a 48Ca beam if a 250Cm target would be prepared. In this case we get a real chance to reach the island of stability owing to a possible beta(+) decay of 291114 and 287112 nuclei formed in this reaction with a cross section of about 0.8 pb. A macroscopic amount of the long-living SH nuclei located at the island of stability may be produced by using the pulsed nuclear reactors of the next generation only if the neutron fluence per pulse will be increased by about three orders of magnitude. Multinucleon transfer processes look quite promising for the production and study of neutron-rich heavy nuclei located in upper part of the nuclear map not reachable by other reaction mechanisms. Reactions with actinide beams and targets are of special interest for synthesis of new neutron-enriched transfermium nuclei and not-yet-known nuclei with closed neutron shell N=126 having the largest impact on the astrophysical r-process. The estimated cross sections for the production of these nuclei allows one to plan such experiments at currently available accelerators.
Realistic level density calculation for heavy nuclei
Energy Technology Data Exchange (ETDEWEB)
Cerf, N. [Institut de Physique Nucleaire, Orsay (France); Pichon, B. [Observatoire de Paris, Meudon (France); Rayet, M.; Arnould, M. [Institut d`Astronomie et d`Astrophysique, Bruxelles (Belgium)
1994-12-31
A microscopic calculation of the level density is performed, based on a combinatorial evaluation using a realistic single-particle level scheme. This calculation relies on a fast Monte Carlo algorithm, allowing to consider heavy nuclei (i.e., large shell model spaces) which could not be treated previously in combinatorial approaches. An exhaustive comparison of the predicted neutron s-wave resonance spacings with experimental data for a wide range of nuclei is presented.
Masses of nuclei close to the dripline
Herfurth, F; Beck, D; Blaum, K; Bollen, G; Kellerbauer, A G; Kluge, H J; Lunney, M D; Rodríguez, D; Schwarz, S; Sikler, G; Weber, C
2003-01-01
Mass measurements of radioactive nuclides are one of the cornerstones of our understanding of the nucleus. The Penning trap spectrometer ISOLTRAP performs direct mass measurements far away from the valley of stability, as well as high-precision measurements of key nuclei to anchor long decay chains. Both schemes provide valuable information on the dripline itself and on nuclei in its close vicinity. (10 refs) .
Effective Field Theory for Lattice Nuclei
Barnea, N.; Contessi, L.; Gazit, D.; Pederiva, F.; van Kolck, U.
2013-01-01
We show how nuclear effective field theory (EFT) and ab initio nuclear-structure methods can turn input from lattice quantum chromodynamics (LQCD) into predictions for the properties of nuclei. We argue that pionless EFT is the appropriate theory to describe the light nuclei obtained in recent LQCD simulations carried out at pion masses much heavier than the physical pion mass. We solve the EFT using the effective-interaction hyperspherical harmonics and auxiliary-field diffusion Monte Carlo ...
Synthesis of superheavy nuclei: Obstacles and opportunities
Directory of Open Access Journals (Sweden)
Zagrebaev V.I.
2015-01-01
Full Text Available There are only 3 methods for the production of heavy and superheavy (SH nuclei, namely, fusion reactions, a sequence of neutron capture and beta(- decay and multinucleon transfer reactions. Low values of the fusion cross sections and very short half-lives of nuclei with Z<120 put obstacles in synthesis of new elements. At the same time, an important area of SH isotopes located between those produced in the cold and hot fusion reactions remains unstudied yet. This gap could be filled in fusion reactions of 48Ca with available lighter isotopes of Pu, Am, and Cm. New neutron-enriched isotopes of SH elements may be produced with the use of a 48Ca beam if a 250Cm target would be prepared. In this case we get a real chance to reach the island of stability owing to a possible beta(+ decay of 291114 and 287112 nuclei formed in this reaction with a cross section of about 0.8 pb. A macroscopic amount of the long-living SH nuclei located at the island of stability may be produced by using the pulsed nuclear reactors of the next generation only if the neutron fluence per pulse will be increased by about three orders of magnitude. Multinucleon transfer processes look quite promising for the production and study of neutron-rich heavy nuclei located in upper part of the nuclear map not reachable by other reaction mechanisms. Reactions with actinide beams and targets are of special interest for synthesis of new neutron-enriched transfermium nuclei and not-yet-known nuclei with closed neutron shell N=126 having the largest impact on the astrophysical r-process. The estimated cross sections for the production of these nuclei allows one to plan such experiments at currently available accelerators.
Secondary beams and the synthesis of exotic nuclei
International Nuclear Information System (INIS)
With the advent of modern fast cycling synchrotrons capable of delivering high intensity heavy ion beams up to uranium, the production of secondary radioactive ion beams (RIBs) with sufficient intensity has become feasible. The basic production mechanism is the fragmentation of near relativistic heavy ion beams on light targets. The physical facts underlying the efficient conversion of stable beams into RIBs are: (1) at beam energies of several 100 MeV/A thick conversion targets (1-10 g/cm2) can be used, which, for nuclei near stability, convert on the order of .1 to 1% of the primary beam into secondary beams, (2) the secondary beams are emitted into a narrow phase space (small transverse and longitudinal emittances), and (3) these emittances are of the correct magnitude to match the acceptances of suitably designed storage accumulator rings. From a primarily experimental point of view experiments with RIBs can be divided into three categories: (1) Experiments that measure properties of the secondary beams as such, like masses, Q-values, and magnetic moments, β-decay studies of implanted exotic nuclei, and Moessbauer spectroscopy. (2) Experiments that use external targets. This includes the synthesis of exotic nuclei with neutron- or proton-rich beams, implantation of RIBs for tracer studies in solid state physics, and biomedical applications. Many well established experimental techniques can be used in these two categories, while (3), the use of internal targets, represents in many ways new challenges to experimenters in nuclear and atomic physics
Temperature-Dependent Fission Barriers of Superheavy Nuclei
Pei, J C; Sheikh-Javid, A; Kerman, A K
2009-01-01
The dependence of fission barriers on the excitation energy of the compound nucleus impacts the survival probability of superheavy nuclei synthesized in heavy-ion fusion reactions. We study the temperature-dependent fission barriers by means of the self-consistent nuclear density functional theory. The equivalence of isothermal and isentropic descriptions is demonstrated. The effect of the particle gas is found to be negligible in the range of temperatures studied. Calculations have been carried out for $^{264}$Fm, $^{272}$Ds, $^{278}$112, $^{292}$114, and $^{312}$124. For nuclei around $^{278}$112 produced in "cold fusion" reactions, we predict a more rapid decrease of fission barriers with temperature as compared to the nuclei around $^{292}$114 synthesized in "hot fusion" experiments. This is explained in terms of the difference between the ground-state and fission-barrier temperatures. Our calculations are consistent with the long survival probabilities of the superheavy elements produced in Dubna with th...
Symmetry Energy and Isovector Giant Dipole Resonance in Finite Nuclei
Institute of Scientific and Technical Information of China (English)
CAO Li-Gang; MA Zhong-Yu
2008-01-01
We study the relationship between the properties of the isovector giant dipole resonance of finite nuclei and the symmetry energy in the framework of the relativistic mean field theory with six different parameter sets of nonlinear effective Lagrangian.A strong linear correlation of excited energies of the dipole resonance in finite nuclei and symmetry energy at and below the saturation density is found.This linear correlation leads to the symmetry energy at the saturation density at the interval 33.0 MeV ≤ S(ρo)≤37.0 MeV.The comparison to the present experimental data in the soft dipole mode of 132 Sn constrains approximately the symmetry energy at ρ = 0.1 fm-3 at the interval 21.2MeV～ 22.5 MeV.It is proposed that a precise measurement of the soft dipole mode in neutron rich nuclei could set up an important constraint on the equation of state for asymmetric nuclear matter.
The collective model of nuclei and its applications
International Nuclear Information System (INIS)
The concepts of collective coordinates, the establishment of Hamiltonian collectives through the model of the drop of liquid or through the symmetry arguments and of the operators in these variables are discussed in this study. The passage of the laboratory system to the principal axis system is discussed thoroughly with the symmetries produced by this transformation, considering a drop in two dimensions. It is also observed that the deformed nuclei have some properties that can be described through the rotation-vibration and symmetric rotor models. The rotation-vibration model concerns the nuclei with axially symmetric deformations in the basic state and its importance is due to the fact that it can predict the nuclear spectrum at low energies. The asymmetric rotor model assumes the existence of triaxial nuclei and considers their collective movements. This model can be modified taking into consideration that vibrations β can also appear. Finally there is a comparison between the two models and the models are also compared with the experiment. (author)
Effective field theory for vibrations in odd-mass nuclei
Pérez, E A Coello
2016-01-01
Heavy even-even nuclei exhibit low-energy collective excitations that are separated in scale from the microscopic (fermion) degrees of freedom. This separation of scale allows us to approach nuclear vibrations within an effective field theory (EFT). In odd-mass nuclei collective and single-particle properties compete at low energies, and this makes their description more challenging. In this article we describe odd-mass nuclei with ground-state spin $I=\\sfrac{1}{2}$ by means of an EFT that couples a fermion to the collective degrees of freedom of an even-even core. The EFT relates observables such as energy levels, electric quadrupole ($E2$) transition strengths, and magnetic dipole ($M1$) moments of the odd-mass nucleus to those of its even-even neighbor, and allows us to quantify theoretical uncertainties. For isotopes of rhodium and silver the theoretical description is consistent with data within experimental and theoretical uncertainties. Several testable predictions are made.
The star formation history of Seyfert 2 nuclei
Fernandes, R C; Melnick, Yu M; Terlevich, E; Terlevich, R J; Kunth, D; Lacerda, R R; Joguet, B
2004-01-01
We present a study of the stellar populations in the central ~ 200 pc of a large and homogeneous sample comprising 79 nearby galaxies, most of which are type 2 Seyferts. The star-formation history of these nuclei is reconstructed by means of state-of-the art population synthesis modeling of their spectra in the 3500--5200 A interval. A QSO-like featureless continuum (FC) is added to the models to account for possible scattered light from a hidden AGN. We find that: (1) The star-formation history of Seyfert 2 nuclei is remarkably heterogeneous: young starbursts, intermediate age, and old stellar populations all appear in significant and widely varying proportions. (2) A significant fraction of the nuclei show a strong FC component, but this FC is not always an indication of a hidden AGN: it can also betray the presence of a young, dusty starburst. (3) We detect weak broad Hbeta emission in several Seyfert 2s after cleaning the observed spectrum by subtracting the synthesis model. These are most likely the weak...
Basic equations of the quasiparticle-phonon nuclear model for deformed even-even nuclei
International Nuclear Information System (INIS)
The equations of the quasiparticle-phonon nuclear model for the description of nonrotational states in deformed even-even nuclei are given in the general form. The Pauli principle is taken into account in the two-phonon components of the states
Selective population of high-j orbitals in Er nuclei by heavy-ion--induced transfer
International Nuclear Information System (INIS)
Selective population of high-j and high-K states in /sup 167,169,171/Er nuclei has been observed in heavy-ion--induced single-neutron-transfer reactions. Gamma rays in coincidence with outgoing particles have been used to aid in level assignments and several previously unobserved high-j states have been identified
Characterization of biological ice nuclei from a lichen.
Kieft, T. L.; Ruscetti, T
1990-01-01
Biological ice nuclei (active at approximately -4 degrees C) were extracted from cells of the lichen Rhizoplaca chrysoleuca by sonication. Sensitivity to proteases, guanidine hydrochloride, and urea showed these nuclei to be proteinaceous. The nuclei were relatively heat stable, active from pH 1.5 to 12, and active without lipids, thereby demonstrating significant differences from bacterial ice nuclei.
Study of neutron-rich nuclei using deep-inelastic reactions
Energy Technology Data Exchange (ETDEWEB)
Lee, I.Y.; Asztalos, S.; Deleplanque, M.; Cederwall, B.; Diamond, R.M.; Fallon, P.; Macchiavelli, A.O.; Phair, L.; Stephens, F.S.; Wozniak, G.J. [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Frauendorf, S.G. [Research Center Rossendorf, Dresden (Germany); Becker, J.A.; Henry, E.A. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Hua, P.F.; Sarantites, D.G. [Washington University, St. Louis, Missouri 63130 (United States); Saladin, J.X. [University of Pittsburgh, Pittsburgh, Pennsylvania 15260 (United States); Yu, C.H. [University of Rochester, Rochester, New York 14627 (United States)
1997-08-01
We have used the {sup 48}Ca+{sup 176}Yb reaction to study the population of high-spin states in neutron-rich nuclei by deep-inelastic reactions. Using Gammasphere, we observed gamma transitions from nuclei several neutrons richer than the target. Yrast states with spin up to 20 were populated in this reaction. High-spin states in {sup 175,177,178}Yb were observed. In this region of reduced pairing, a reference based on experimental data was used to derive experimental Routhians. Systematics of experimental Routhians in neutron-rich Yb nuclei compare well with cranked shell-model calculations. {copyright} {ital 1997} {ital The American Physical Society}
Systematics of Scissors Mode in Gd Nuclei from Experiments with the DANCE Detector
Kroll, J.; Agvaanluvsan, U.; Baramsai, B.; Becker, J. A.; Bečvář, F.; Bredeweg, T. A.; Chyzh, A.; Couture, A.; Dashdorj, D.; Haight, R. C.; Jandel, M.; Keksis, A. L.; Krtička, M.; Mitchell, G. E.; O'Donnell, J. M.; Parker, W.; Rundberg, R. S.; Ullmann, J. L.; Valenta, S.; Vieira, D. J.; Walker, C. L.; Wilhelmy, J. B.; Wouters, J. M.; Wu, C. Y.
2014-05-01
Multi-step cascade γ-ray spectra from neutron capture at isolated resonances of 152,154-158Gd nuclei were measured at the LANSCE/DANCE time-of-flight facility in Los Alamos National Laboratory. The main objective of these experiments was to obtain new information on photon strength functions with emphasis on the role of the M1 scissors mode vibration. An analysis of the data obtained shows that the scissors mode plays a significant role in the ground state transitions, as well as in the transitions populating all excited states of the studied nuclei. The estimates of the scissors mode strength indicate that for 157,159Gd this strength is significantly higher than in neighboring even-even nuclei 156,158Gd. The results are compared with the (γ,γ‧) data for the ground-state scissors mode and the results from 3He-induced reactions.
High spin spectroscopy of near spherical nuclei: Role of intruder orbitals
Energy Technology Data Exchange (ETDEWEB)
Bhattacharyya, S.; Bhattacharjee, T.; Mukherjee, G. [Variable Energy Cyclotron Centre, 1/AF Bidhan Nagar, Kolkata - 700064 (India); Chanda, S. [Fakir Chand College, Diamond Herbour, West Bengal (India); Banerjee, D.; Das, S. K.; Guin, R. [Radiochemistry Division, Variable Energy Cyclotron Centre, BARC, Kolkata - 700064 (India); Gupta, S. Das [Variable Energy Cyclotron Centre, 1/AF Bidhan Nagar, Kolkata - 700064, India and Saha Institute of Nuclear Physics, Kolkata-700064 (India); Pai, H. [Variable Energy Cyclotron Centre, 1/AF Bidhan Nagar, Kolkata - 700064, India and Institut für Kernphysik, Technische Universität Darmstadt, Schlossgartenstrasse 9, 64289 Darmstadt (Germany)
2014-08-14
High spin states of nuclei in the vicinity of neutron shell closure N = 82 and proton shell closure Z = 82 have been studied using the Clovere Ge detectors of Indian National Gamma Array. The shape driving effects of proton and neutron unique parity intruder orbitals for the structure of nuclei around the above shell closures have been investigated using light and heavy ion beams. Lifetime measurements of excited states in {sup 139}Pr have been done using pulsed-beam-γ coincidence technique. The prompt spectroscopy of {sup 207}Rn has been extended beyond the 181μs 13/2{sup +} isomer. Neutron-rich nuclei around {sup 132}Sn have been produced from proton induced fission of {sup 235}U and lifetime measurement of low-lying states of odd-odd {sup 132}I have been performed from offline decay.
Release of cell-free ice nuclei by Erwinia herbicola.
Phelps, P; Giddings, T. H.; Prochoda, M; Fall, R
1986-01-01
Several ice-nucleating bacterial strains, including Erwinia herbicola, Pseudomonas fluorescens, and Pseudomonas syringae isolates, were examined for their ability to shed ice nuclei into the growth medium. Only E. herbicola isolates shed cell-free ice nuclei active at -2 to -10 degrees C. These cell-free nuclei exhibited a freezing spectrum similar to that of ice nuclei found on whole cells, both above and below -5 degrees C. Partially purified cell-free nuclei were examined by density gradie...
Binding energy and stability of heavy and superheavy nuclei
Kolesnikov, N.N.
2012-01-01
Three different ways for description of binding energy of superheavy nuclei are discussed. First, one can consider superheavy nuclei as a part of a whole system of nuclei for which a global mass formula is found. Another way is the detailed local description of energy of superheavy nuclei taking into account the effects of shells and subshells. The third way of description, applied for nuclei in the region limited by principal magic numbers, is attached to the beta-stability line.
Relativistic mean field models for finite nuclei and neutron stars
Chen, Wei-Chia
In this dissertation we have created theoretical models for finite nuclei, nuclear matter, and neutron stars within the framework of relativistic mean field (RMF) theory, and we have used these models to investigate the elusive isovector sector and related physics, in particular, the neutron-skin thickness of heavy nuclei, the nuclear symmetry energy, and the properties of neutron stars. To build RMF models that incorporate collective excitations in finite nuclei in addition to their ground-state properties, we have extended the non-relativistic sum rule approach to the relativistic domain. This allows an efficient estimate of giant monopole energies. Moreover, we have combined an exact shell-model-like approach with the mean-field calculation to describe pairing correlations in open-shell nuclei. All the ingredients were then put together to establish the calibration scheme. We have also extended the transformation between model parameters and pseudo data of nuclear matter within the RMF context. Performing calibration in this pseudo data space can not only facilitate the searching algorithm but also make the pseudo data genuine model predictions. This calibration scheme is also supplemented by a covariance analysis enabling us to extract the information content of a model, including theoretical uncertainties and correlation coefficients. A series of RMF models subject to the same isoscalar constraints but one differing isovector assumption were then created using this calibration scheme. By comparing their predictions of the nuclear matter equation of state to both experimental and theoretical constraints, we found that a small neutron skin of about 0.16 fm in Pb208 is favored, indicating that the symmetry energy should be soft. To obtain stronger evidence, we proceeded to examine the evolution of the isotopic chains in both oxygen and calcium. Again, it was found that the model with such small neutron skin and soft symmetry energy can best describe both isotopic
Dipole Excitations of Unstable Neutron-Rich Nuclei
International Nuclear Information System (INIS)
Coulomb breakup of high-energy secondary beams of unstable nuclei serves in nuclear structure investigations of neutron-rich isotopes. A summary of the respective research activities at GSI is presented, covering isotopes from helium to oxygen. The breakup is mediated through dipole excitations in to the continuum. Non-resonant excitations in to the continuum near the dissociation threshold deliver information on the single-particle ground-state structure. Resonant excitation into the giant resonance domain is also observed. In addition, a brief outlook on future activities at GSI is given. (author)
Pulsars: Macro-nuclei with 3-flavour symmetry
Xu, Renxin
2015-01-01
A pulsar-like compact star is the rump left behind after a supernova where normal baryonic matter is intensely compressed by gravity, but the real state of such compressed baryonic matter is still not well understood because of the non-perturbative nature of the fundamental color interaction. We argue that pulsars could be of condensed matter of quark clusters, i.e., "quark-cluster stars" which distinguish from conventional neutron and quark stars. In comparison with 2-flavour symmetric micro-nuclei, a quark-cluster star could simply be considered as a macro-nucleus with 3-flavour symmetry. New research achievements both theoretical and observational are briefly presented.
Collective modes in light nuclei from first principles.
Dytrych, T; Launey, K D; Draayer, J P; Maris, P; Vary, J P; Saule, E; Catalyurek, U; Sosonkina, M; Langr, D; Caprio, M A
2013-12-20
Results for ab initio no-core shell model calculations in a symmetry-adapted SU(3)-based coupling scheme demonstrate that collective modes in light nuclei emerge from first principles. The low-lying states of 6Li, 8Be, and 6He are shown to exhibit orderly patterns that favor spatial configurations with strong quadrupole deformation and complementary low intrinsic spin values, a picture that is consistent with the nuclear symplectic model. The results also suggest a pragmatic path forward to accommodate deformation-driven collective features in ab initio analyses when they dominate the nuclear landscape. PMID:24483740
Cluster Features in Reactions and Structure of Heavy Nuclei
Adamian, G G; Jolos, R V; Scheid, W; Shneidman, T M
2003-01-01
Cluster effects in the structure of heavy nuclei are considered. The properties of the states of the alternating parity bands in Ra, Th, U and Pu isotopes are analyzed within a cluster model. The model is based on the assumption that cluster type shapes are produced by the motion of the nuclear system in the mass asymmetry coordinate. The results of calculations of the spin dependence of the parity splitting and of the electric multipole transition moments are in agreement with the experimental data.
Quantum fluctuations and stability of tetrahedral deformations in atomic nuclei
Zberecki, K; Magierski, P; Schunck, N
2006-01-01
The possible existence of stable axial octupole and tetrahedral deformations is investigated in $^{80}$Zr and $^{98}$Zr. HFBCS calculations with parity projection have been performed for various parametrizations of the Skyrme energy functional. The correlation and excitation energies of negative parity states associated with shape fluctuations have been obtained using the generator coordinate method (GCM). The results indicate that in these nuclei both the axial octupole and tetrahedral deformations are of dynamic character and possess similar characteristics. Various Skyrme forces give consistent results as a function of these two octupole degrees of freedom both at the mean-field level as well as for configuration mixing calculations.
Direct Neutron Capture for Magic-Shell Nuclei
Krausmann, E.; Balogh, W.; Oberhummer, H.; Rauscher, T.; Kratz, K.-L.; Ziegert, W.
1995-01-01
In neutron capture for magic--shell nuclei the direct reaction mechanism can be important and may even dominate. As an example we investigated the reaction $^{48}$Ca(n,$\\gamma)^{49}$Ca for projectile energies below 250\\,keV in a direct capture model using the folding procedure for optical and bound state potentials. The obtained theoretical cross sections are in agreement with the experimental data showing the dominance of the direct reaction mechanism in this case. The above method was also ...
Multi-Pass Adaptive Voting for Nuclei Detection in Histopathological Images
Lu, Cheng; Xu, Hongming; Xu, Jun; Gilmore, Hannah; Mandal, Mrinal; Madabhushi, Anant
2016-01-01
Nuclei detection is often a critical initial step in the development of computer aided diagnosis and prognosis schemes in the context of digital pathology images. While over the last few years, a number of nuclei detection methods have been proposed, most of these approaches make idealistic assumptions about the staining quality of the tissue. In this paper, we present a new Multi-Pass Adaptive Voting (MPAV) for nuclei detection which is specifically geared towards images with poor quality staining and noise on account of tissue preparation artifacts. The MPAV utilizes the symmetric property of nuclear boundary and adaptively selects gradient from edge fragments to perform voting for a potential nucleus location. The MPAV was evaluated in three cohorts with different staining methods: Hematoxylin & Eosin, CD31 & Hematoxylin, and Ki-67 and where most of the nuclei were unevenly and imprecisely stained. Across a total of 47 images and nearly 17,700 manually labeled nuclei serving as the ground truth, MPAV was able to achieve a superior performance, with an area under the precision-recall curve (AUC) of 0.73. Additionally, MPAV also outperformed three state-of-the-art nuclei detection methods, a single pass voting method, a multi-pass voting method, and a deep learning based method. PMID:27694950
Shell Structure Evolution in Nuclei far from the Valley of Stability: Recent Results from GANIL
International Nuclear Information System (INIS)
Shell structure evolution in nuclei situated at the extremes of neutron and proton excess are investigated using in-beam gamma spectroscopy techniques with radioactive beams at GANIL. A selection of results obtained very recently is presented: i) The reduced transition probabilities B(E2;01+ → 2+) of the neutron-rich 74Zn and 70Ni nuclei have been measured using Coulomb excitation at intermediate energy. An unexpected large proton core polarization has been found in 70Ni and interpreted as being due to the monopole interaction between the neutron g9/2 and protons f7/2 and f5/2 spin-orbit partner orbitals. ii) Two proton knock-out reactions has been performed in order to study the most neutron-rich nuclei at the N=28 shell closure. Gamma rays spectra and momentum distribution have been obtained for 42Si and neighboring nuclei. Evidence has been found for a persistence of the deformation at N=28 down to Silicon despite a relatively large Z=14 gap. iii) The in-beam gamma spectroscopy of 36Ca performed using neutron knock-out reactions revealed that 36Ca is as doubly magic as 36S. The Coulomb energy difference of the first 2+ state in this T=2, A=36 mirror nuclei reveals one of largest isospin symmetry breaking in nuclei
Intermediate/high energy probes and the structure of nuclei. Progress report
International Nuclear Information System (INIS)
Quarks and gluons in nuclei are essential to a complete understanding of the response of nuclei to high energy probes. We propose to obtain evidence of the behavior of quarks in nuclei through theoretical analyses of recent data. Deep inelastic lepton scattering on nuclei provides the least ambiguous signature of quark behavior and recent data from SLAC and CERN show some remarkable features. According to our latest analyses, the quark cluster model we indroduced in1981 provides a framework to explain much of the existing data. We propose to improve the model by eliminating a number of approximations and to incorporate more information from QCD regarding the properties of six and nine quark clusters. We also propose to apply the model to predict results for particle production in hadron-nucleus and nucleus-nucleus collisions. Finally, we propose a series of investigations into the quantum statistical properties of nuclei using microscopic many body theory with the goal to obtain the equation of state of finite nuclei
Theory of two-step two-proton decays of nuclei
Kadmensky, S. G.; Ivankov, Yu. V.
2014-12-01
A general theory of many-body diagonal and nondiagonal one-proton decays of spherical and deformed nuclei is developed on the basis of an approach not employing R-matrix theory in describing deep-subbarrier alpha and one-proton decays of nuclei but relying on integral formulas for the widths with respect to these decays. With the aid of this theory and by means of a diagram technique, a formalism is developed for describing two-step two-proton decays of a ( Z, A) parent nucleus, which proceed as two successive time-separated one-proton decays of the parent and intermediate [( Z - 1, A - 1)] nuclei, these decays being related by the Green's function for the intermediate nucleus, G( Z - 1, A - 1). It is shown that, upon taking into account, in this Green's function, intermediate-nucleus states that are on- and off-shell states for the decaying system, there arise, respectively, sequential and virtual two-proton decays of parent nuclei. Expressions for the widths with respect to sequential and virtual two-proton decays from the ground and excited states of spherical and deformed nuclei and for the angular and energy distributions of emitted protons are obtained.
Rotational spectra and parity splitting in nuclei with strong octupole correlations
International Nuclear Information System (INIS)
A formula is suggested to describe the energies of positive- and negative-parity states belonging to the ground-state alternating-parity rotational bands in nuclei with significant octupole correlations. The agreement with experimental data is quite good for actinide nuclei. This formula corresponds to the parity splitting from a one-dimensional potential well. It leads to a common moment of inertia for both parities at least for low angular momenta. At high angular momenta a slight difference in the moments of inertia is found, which is presumably due to backbending. ((orig.))
Investigations on Nuclei near Z- 82 in Relativistic Mean Field Theory with FSUGold
Institute of Scientific and Technical Information of China (English)
圣宗强; 任中洲
2012-01-01
In this work, the ground-state properties of Pt, Hg, Pb, and Po isotopes have been systematically investigated in the deformed relativistic mean field (RMF) theory with the new parameter set FSUGold. The calculated results show that FSUGold is as successful as NL3 in reproducing the ground-state binding energies of the nuclei in this region. The calculated two- neutron separation energies, quadrupole deformations, and root-mean-square charge radii are in agreement with the experimental data. The parameter set FSUGold can successfully describe the shell effect of the neutron magic number N = 126 and give smaller neutron skin thicknesses than NL3 for all the nuclei considered.
Study of Neutron Magic Drip-Line Nuclei within Relativistic Mean Field plus BCS Approach
Saxena, G.; Singh, D.; Kaushik, M.; Yadav, H. L.; Toki, H.
2013-01-01
Encouraged by the success of RMF+BCS approach for the description of the ground state properties of the chains of isotopes of proton magic nuclei with proton number Z=8, 20, 28, 50 and 82 as well as those of proton sub-magic nuclei with Z=40, we have further employed it, in an analogous manner, for a detailed calculations of the ground state properties of the neutron magic isotones with neutron number N = 8, 20, 28, 50, 82 and 126 as well as those of neutron sub-magic isotones with N = 40 usi...
Fast neutron inelastic scattering from nuclei
International Nuclear Information System (INIS)
The need for accurate values of inelastic scattering cross sections appears when the requests for neutron data for reactors and other applied purposes are considered. These requests are partly related to values for spherical nuclei, well studied over many years. These studies were extensively considered in two review papers presented, in 1976, at the International Conference on the Interactions of Neutrons with nuclei. Other requests are related to vibrational and rotational nuclei, and relevant studies have been recently performed. The quality of these investigations and the large number of recent results have lead to concentration on them as the topic of the present review. The constant improvements of the experimental techniques permits precise measurements of inelastic scattering cross sections to the first excited levels over a range of incident energies, such that different reactions mechanisms are predominant in different parts of that range of energies. Quadrupole, hexadecapole and octupole deformation parameters of the target nuclei can be deduced from the data using phenomenological models. The successful application of the analysis over the range of energies leads to the conclusion that reliable information on the shape of the nuclei has been derived. The validity of the various models, which include direct interaction and compound nucleus reaction mechanisms, is discussed in connection with analyses of recent experiments. (author)
α-cluster structure and density waves in oblate nuclei
International Nuclear Information System (INIS)
Pentagon and triangle shapes in 28Si and 12C are discussed in relation to nuclear density waves. In the antisymmetrized molecular dynamics calculations, the Kπ=5- band in 28Si and the Kπ=3- band in 12C are described by the pentagon and triangle shapes, respectively. These negative-parity bands can be interpreted as the parity partners of the Kπ=0+ ground bands and they are constructed from the parity-asymmetric-intrinsic states. The pentagon and the triangle shapes originate in 7α- and 3α-cluster structures, respectively. In a mean-field picture, they are described also by the static one-dimensional density waves at the edge of the oblate states. In analyses with ideal α-cluster models using Brink-Bloch cluster wave functions and that with a simplified model, we show that the static edge density waves for the pentagon and triangle shapes can be understood by spontaneous breaking of axial symmetry, i.e., the instability of the oblate states with respect to the edge density waves. The density wave is enhanced in the Z=N nuclei due to the proton-neutron coherent density waves, while it is suppressed in Z≠N nuclei.
IBM-2 calculations of some even-even neodymium nuclei
International Nuclear Information System (INIS)
In this study, we determined the most appropriate Hamiltonian that is needed for present calculations of nuclei in the A≅130 region by the view of projection of IBM-2 parameters onto IBM-1. The interacting boson model has been widely used for describing the quadrupole collective states of the medium heavy nuclei and no distinction is made between proton and neutron variables when the first version of the model (IBM-1) is applied. So, triaxiality can be described explicitly, through the introduction of cubic terms in the boson operators. However, the microscopic foundations state certainly that it is very important to describe the proton and neutron variables explicitly. This is also a generalized definition of the second version of the IBA-model (IBM-2 model). Using the best-fitted values of parameters in the Hamiltonian of the IBM-2, we have calculated energy levels and B(E2) values for a number of transitions in 144,146,148,150,152,154Nd. The results were compared with the previous experimental and theoretical data and it is observed that they are in good agreement. Many B(E2) values that are still not known so far are stated and the set of parameters used in these calculations is the best approximation that has been carried out so far. It has turned out that the interacting boson approximation (IBA) is fairly reliable for the calculation of spectra in the entire set of 144,146,148,150,152,154Nd isotopes
Low-energy {pi}{pi} photoproduction off nuclei
Energy Technology Data Exchange (ETDEWEB)
Muehlich, P.; Alvarez-Ruso, L.; Buss, O.; Mosel, U
2004-08-12
In the present Letter we investigate {pi}{sup 0}{pi}{sup 0} and {pi}{sup {+-}}{pi}{sup 0} photoproduction off complex nuclei at incident beam energies of 400-460 MeV. Simulations of two pion photoproduction on protons and nuclei are performed by means of a semi-classical BUU transport model including a full coupled-channel treatment of the final state interactions. Elastic scattering of the final state pions with the nucleons in the surrounding nuclear medium is found to yield a downward shift of the {pi}{pi} invariant mass distribution. We show that the target mass dependence of the {pi}{sup 0}{pi}{sup 0} invariant mass spectrum as measured by the TAPS Collaboration can be explained without introducing medium effects beyond absorption and quasi-elastic scattering of the final state particles. On the other hand, we find considerable discrepancies with the data in the {pi}{sup {+-}}{pi}{sup 0} channel, which are not understood.
Supermassive Black Holes in Galactic Nuclei
Ho, L C
1998-01-01
I review the status of observational determinations of central masses in nearby galactic nuclei. Results from a variety of techniques are summarized, including ground-based and space-based optical spectroscopy, radio VLBI measurements of luminous water vapor masers, and variability monitoring studies of active galactic nuclei. I will also discuss recent X-ray observations that indicate relativistic motions arising from the accretion disks of active nuclei. The existing evidence suggests that supermassive black holes are an integral component of galactic structure, at least in elliptical and bulge-dominated galaxies. The black hole mass appears to be correlated with the mass of the spheroidal component of the host galaxy. This finding may have important implications for many astrophysical issues.
Shape phase mixing in critical point nuclei
Budaca, R
2016-01-01
Spectral properties of nuclei near the critical point of the quantum phase transition between spherical and axially symmetric shapes are studied in a hybrid collective model which combines the $\\gamma$-stable and $\\gamma$-rigid collective conditions through a rigidity parameter. The model in the lower and upper limits of the rigidity parameter recovers the X(5) and X(3) solutions respectively, while in the equally mixed case it corresponds to the X(4) critical point symmetry. Numerical applications of the model on nuclei from regions known for critical behavior reveal a sizable shape phase mixing and its evolution with neutron or proton numbers. The model also enables a better description of energy spectra and electromagnetic transitions for these nuclei.
Nucleon localization in light and heavy nuclei
Zhang, C L; Nazarewicz, W
2016-01-01
An electron localization measure was originally introduced to characterize chemical bond structures in molecules. Recently, a nucleon localization based on Hartree-Fock densities has been introduced to investigate $\\alpha$-cluster structures in light nuclei. Compared to the local nucleonic densities, the nucleon localization function has been shown to be an excellent indicator of shell effects and cluster correlations. Using the spatial nucleon localization measure, we investigate the cluster structures in deformed light nuclei and study the emergence of fragments in fissioning heavy nuclei. To illustrate basic concepts of nucleon localization, we employ the deformed harmonic oscillator model. Realistic calculations are carried out using self-consistent nuclear density functional theory with quantified energy density functionals optimized for fission studies. We study particle densities and spatial nucleon localization distributions for deformed cluster configurations of $^{8}$Be and $^{20}$Ne, and also along...
Energy Technology Data Exchange (ETDEWEB)
Khadiri, Najia [Institut de Recherche Subatomique, CNRS-IN2P3 - Universite Louis Pasteur, 67 - Strasbourg (France)
1997-10-17
This work is devoted to nuclear structure studies of superdeformed states in the second potential well. Under focus are the gadolinium isotopes and in particular the {sup 147}Gd nucleus. High spin states in {sup 147}Gd have been populating by {sup 122}Sn ({sup 30}Si,5n){sup 147}Gd fusion-evaporation reaction with a silicon beam of 158 MeV delivered by the VIVITRON accelerator of the Institut de Recherches Subatomiques. The nucleus {gamma} de-excitations have been measured using the EUROGAM II {gamma}-ray multidetector. On the basis of multiple coincidences, four new superdeformed (SD) rotational bands have been assigned to {sup 147}Gd nucleus. Nuclear structures corresponding to these bands have been investigated by shell model calculations using a harmonic oscillator potential with cranking, in the Nilsson Strutinsky formalism. Comparison of dynamical moments of inertia of band (1) and (5) in {sup 147}Gd with {sup 148}Gd(2) and {sup 146}Gd(1) SD bands has fixed the role of the [651 1/2]{alpha} = -1/2 orbital crossing frequency. Theoretical calculations reproduce quite well the {sup 148}Gd(2), {sup 127}Gd(1,5) and G{sup 146}Gd(1) dynamical moments of inertia. Using the particle hole excitation nature of {sup 149,148,147,146}Gd bands, effective spin alignment of [651 1/2]{alpha}= {+-}1/2, [770 1/2]{alpha} = -1/2 and [441 1/2]{alpha} = +1/2 orbitals have been deduced from the experiment in agreement with the theoretical values. Of particular interest, the spin alignment measured for the [441 1/2]{alpha} +1/2 orbital, with a value close to zero, is in contradiction with the value predicted by the Pseudo SU(3) model, formalism often used to explain the identical band phenomenon. (author) 68 refs., 41 figs., 17 tabs.
Towards Superheavies: Spectroscopy of 94 < Z < 98, 150 < N < 154 Nuclei
Chowdhury, P.; Hota, S. S.; Qiu, Y.; Ahmad, I.; Carpenter, M. P.; Greene, J. P.; Janssens, R. V. F.; Khoo, T. L.; Kondev, F. G.; Lauritsen, T.; Lister, C. J.; Seweryniak, D.; Zhu, S.
2016-09-01
The heaviest nuclei where excitations above the ground state can be studied lie near Z ~ 100. These nuclear structure studies are important testing grounds for theoretical models that aim to describe superheavy nuclei. To study the highest neutron orbitals (150 ≤ N ≤ 154), we have populated high angular momentum states in a series of Pu (Z = 94), Cm (Z = 96) and Cf (Z = 98) nuclei, via inelastic and transfer reactions, with heavy beams on long-lived radioactive actinide targets. Multiple collective excitation modes and structures were identified, and their configurations deduced. Quasiparticle alignments are mapped, with odd-A band structures helping identify specific orbital contributions via blocking arguments. Higher-order multipole shapes are observed to play a significant role in disentangling competing neutron and proton alignments. The N > 152 data provide new perspectives on physics beyond the N = 152 sub-shell gap.