Effect of selenite on 86Rb uptake by rat lens
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
Vectorial (transcellular) transport of potassium (86Rb+) by cultured Sertoli cells
Sertoli cells from rats aged 25 days were grown on Millipore filters (pore diameter 0.5 micron) for 7 days and were then used for determination of transport of 86Rb+ through the cells (base to apex); this procedure is referred to as measuring transcellular or vectorial transport. Sertoli cells were also used to measure apical efflux of 86Rb+ by loading the cells with the isotope to steady state and then incubating cells so that the apical surfaces were in contact with medium not containing 86Rb+, from which samples were taken. Basal efflux was measured in the same way except that the opposite surface of the cells was in contact with the medium. Cells grown on filters treated with collagen IV plus fibronectin showed transcellular transport of 86Rb+; t1/2 for equilibration across the cells was 9-12 min. The rate of transport was accelerated by addition of (Bu)2cAMP, forskolin, or FSH to the incubation medium. Half-maximal responses were seen with (Bu)2cAMP at 0.2 mM and with forskolin at 20 microM. Apical efflux (t1/2 9.8 +/- 2.1 min) was not influenced by the presence or absence of K+ in the medium nor by azide or (Bu)2cAMP. Basal efflux showed similar values for t1/2 in the presence of K+ (9.7 +/- 1.9 min) and values of 21.4 +/- 4.2 min in the absence of K+. Vectorial transport of 86Rb+ by these cells may account for the K+ gradient seen in the seminiferous tubule and appears to result from a basolateral potassium pump together with an apical membrane that is permeable to K+
Release of 86Rb from rat submandibular gland slices: relation to sodium pump activity
Slices of rat submandibular gland were preloaded with 86Rb, an isotope that can substitute for K+ in the K+ release process. The efflux of 86Rb was monitored in a superfusion apparatus that efficiently removed the 86Rb as it exited from the tissue slices. Carbachol and the calcium ionophore A23187 activated a calcium-dependent increase in 86Rb efflux. Dibutyryl cGMP had no detectable effect on 86Rb efflux in contrast to its activation of ouabain-sensitive uptake of 86Rb observed in an earlier study. The stimulated release of 86Rb was not dependent on the presence of either sodium or chloride ion. When 86Rb efflux was stimulated by carbachol, the efflux rate returned toward the basal rate after a few minutes of exposure to carbachol in the medium. If ouabain was then introduced into the superfusate, a large increase in efflux was stimulated. In the absence of carbachol, only a small increase in 86Rb efflux was stimulated by ouabain. The effect of ouabain indicates that there was a substantial recycling of 86Rb between the release and uptake processes in the extracellular space of the tissue slice. The significance of this observation is discussed
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
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
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
The uptake of 86Rb+ into photoautotrophic mesophyll cells of Papaver somniferum
Uptake of 86Rb+, used as a tracer for potassium, into isolated photoautotrophic mesophyll cells of Papaver somniferum was weakly but consistently stimulated in the light. It showed mono-phasic saturation kinetics with a pH optimum of 7.0, a Vsub(max) of 6.7 μmol mg-1 Chl x h-1 and a Ksub(m) of 2.7 mmol l-1. Different anions as Cl-, NO3- and PO43- had no effects on 86Rb+ uptake. Sodium ions influenced Rb+-uptake very weakly, indicating a high K+ -specificity of the mesophyll cell plasmalemma. Fusicoccin stimulated 86Rb+ -uptake strongly whereas abscisic acid inhibited uptake only following preincubation for two hours. Nitrite, CCCP and Dio-9 inhibited 86Rb+-uptake which gives evidence that this process is dependent on intact pH-gradients within the cells and on ATP-formation. (orig.)
Inhibition of white light of 86Rb+ absorption in the root apex of corn
Measurements of cell lengths made at 0.5 millimeter intervals in median longitudinal sections of the primary roots of corn (Zea mays) were used to construct a growth curve. The region 1.5 to 4.0 millimeters from the apex contained the largest number of elongating cells. Absorption of 86Rb+ was measured using intact, dark-grown corn seedlings. Following uptake and exchange, the terminal 8.0 millimeters of each root was cut into four 2.0 millimeter segments. Maximum 86Rb+ uptake occurred in the region from 0.0 to 4.0 millimeter from the root tip. Washing the intact primary root in fresh 2.0 millimolar CaSO4 for 2 hours prior to uptake augmented the rate of 86Rb+ uptake in all regions. Illumination with white light during washing caused a reduction of 86Rb+ uptake as compared with controls washing in darkness, and the region of greatest light response was the region of elongation. Removal of the coleoptile prior to washing did not prevent the light inhibition of subsequent 86Rb+ uptake. Removal of the root cap prior to washing in light partially reversed the light-induced inhibition of the washing response
Environmental effects on energy metabolism and 86Rb elimination rates of fishes
Relationships between energy metabolism and the turnover rates of number of important chemical and radiological elements (particularly the Group IA alkali metals: K, Rb, and Cs) have been observed in fishes. Using response surface statistics and fractional factorial ANOVA, the author examined the relative influences of temperature, salinity, food intake rate, mass, and their first order interactions on routine energy metabolism and 86Rb elimination rates. Routine metabolic rates were increased primarily by increased temperature and salinity, with a strong body mass effect and a significant effect of food intake. 86Rb elimination rates were increased primarily by increased temperature and salinity. There were no interactive effects between mass and either temperature or salinity for either routine energy metabolism or 86Rb elimination rates. There was a significant interaction effect between temperature and salinity on routine energy metabolism rates, but not on 86Rb elimination. The authors also observed a relationship between routine energy metabolism and 86Rb elimination rates that may possibly be exploited as a means of estimating energy metabolic rates of fishes in the field. The statistical techniques used in this experiment have broad potential applications in assessing the contributions of combinations of environmental variables on contaminant kinetics, as well as in multiple toxicity testing, in that they greatly simplify experimental designs compared with traditional full-factorial methods
Transport of 86Rb+ in corn leaves as influenced by some growth substances
The transport of 86Rb+ supplied to the middle of young corn leaves was scanned by means of a modified chromatogram scanner and it was found that the movement towards the base was larger than to the apex of both intact and excised leaves. Application of 25 ppm of ABA (abscisic acid) or ethrel (2-chloroethane phosphonic acid) did not affect the pattern of transport. However, the growth substances tested, viz, ABA, ethrel, GA3 and IAA generally enhanced the rate of 86Rb+ transport towards the base of the leaf. (orig.)
Leakage of 86Rb+ after ultraviolet irradiation of Escherichia coli K-12
Stationary phase cultures of a DNA repair proficient Escherichia coli K-12 strain showed a release of intracellular material as assessed by three different methods (260 nm absorption; (methyl-3H) thymidine leakage and 86Rb+ leakage) after broad-band near-UV radiation but not after far-UV (254 nm) radiation. As a control response for membrane damage to cells, this leakage of intracellular material was also determined by each method after mild heat (520C) treatment of E. coli K-12. An action spectrum for the release of 86Rb+ from E. coli K-12 after monochromatic irradiation (254 to 405 nm) is also presented. The action spectrum for lethality (F37 values) shows that leakage of 86Rb+ occurs at fluences around those causing inactivation at wavelengths above 305 nm. In contrast, at wavelengths below 305 nm, leakage of 86Rb+ from irradiated cells can be induced but only at fluences significantly greater than was required to cause cell inactivation. These results indicate that near-UV radiation can damage the cell's permeability barrier which may be significant in causing cell death, whereas the effect is not significant in causing cell death by far-UV radiation where DNA is known to be the main cause of lethality. (author)
Effects of the K+ channel blocking agent, glyburide, on the actions of two K+ channel openers, BRL 34915 (cromakalim) and P 1060 (Leo), a potent pinacidil derivative (N-(t-butyl)-N double-prime-cyano-N'-3-pyridyl-guanidine), were ascertained. Tension responses and 86Rb fluxes in rat portal vein strips and single channel electrophysiological recordings in enzymatically dissociated rat portal vein cells were obtained. Glyburide (0.3 microM) increased spontaneous contractile activity and caused concentration-dependent shifts in the relaxation responses to BRL 34915 and P 1060. Increases in 86Rb efflux were obtained only at much higher concentrations of BRL 34915 or P 1060, and these increases were blocked only at higher concentrations of glyburide (5.0 microM). BRL 34915 and P 1060 specifically increase the open-state probability of the Ca+(+)-activated K+ (maxi-K+) channel, and these actions are blocked by glyburide and also by charybdotoxin. Changes in single channel activity and contractile responsiveness occur at similar concentrations of agonists and antagonists. Thus, the membrane channel in rat portal vein affected by glyburide, BRL 34915 and P 1060 appears to be the Ca+(+)-activated maxi-K+ channel (that does not show ATP dependence under the conditions of these experiments). Concentrations of agonists and antagonists effective on maxi-K+ channel activity correspond to those affecting contractile responsiveness and are lower than those eliciting changes in 86Rb flux
This study was carried out to know the uptake pattern of phosphorous and potassium in rice plants using by two radioisotopes, 32P and 86Rb as tracers for two years, 1987 and 1988. Rice plants were grown in the hydroponic culture with Yoshida's solution, and treated with different temperatures, transpiration suppress, shading, and phosphorous and potassium deletions. The uptake amount of 32P and 86Rb were increased with the increasing temperature in root sphere of rice plant, particularly remarkable increase of 86Rb uptake at 35deg C. The uptake of 32P tended to be promoted at the treatment of low air-high water temperature (17-30deg C), while that of 86Rb was not significantly differenced from different temperature treatments. The effect of transpiration on the uptake of 32P and 86Rb was extremely low. This phenomenon may suggest that the absorption be depending on active uptake rather than passive one by transpiration stream. The total carbohydrate contents of rice root were decreased by shading treatment, resulting significant reduction in the uptake of 32P and 86Rb. The uptake of 86Rb was remarkably increased in the treatment of potassium deletion, but that of 32P was not significantly increased in the delection of phosphorous
Burn-up cross sections of 51Cr, 59Fe, 65Zn, 86Rb, 103Ru
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
We investigate here the hypothesis that the high Ca content of sickle cell anemia (SS) red cells may produce a sustained activation of the Ca2+-dependent K+ permeability (Gardos effect) and that the particularly high Ca levels in the dense SS cell fraction rich in irreversibly sickled cells (ISCs) might account for the Na pump inhibition observed in these cells. We measured active and passive 86Rb+ influx (as a marker for K+) in density-fractionated SS cells before and after extraction of their excess Ca by exposure to the Ca ionophore (A23187) and ethylene glycol tetra-acetic acid and with or without adenosine triphosphate depletion or addition of quinine. None of these maneuvers revealed any evidence of a Ca2+-dependent K leak in SS discocytes or dense cells. Na pump inhibition in the dense SS cells was associated with normal activation by external K+ and a low Vmax that persisted after Ca extraction from the cells. These results are consistent with our recent findings that the excess Ca in these cells is compartmentalized in intracellular inside-out vesicles and unavailable as free Ca2+ to the inner membrane surface. Although the steady-state free cytoplasmic Ca2+ in oxygenated SS cells must be below the levels needed to activate the K+ channel, possible brief activation of the channels of some SS cells resulting from transient elevations of cell Ca2+ during deoxygenation-induced sickling cannot be excluded. The dense, ISC-rich SS cell fraction showed a Ca2+-independent increase in the ouabain-resistant, nonsaturable component of 86Rb+ influx that, if uncompensated by Na+ gain, could contribute to the dehydration of these cells
Effects of two K+ channel openers, cromakalim and pinacidil, on mechanical activity and on 86Rb efflux were compared in strips of dog coronary arteries. Cromakalim and pinacidil produced the relaxation in 20.9 mM K(+)-contracted strips with a pD2 of 6.53 and 5.95, respectively. In 65.9 mM K(+)-contracted strips, high concentrations of pinacidil, but not cromakalim, produced relaxation. Ca+(+)-induced contractions in 80 mM K(+)-depolarized strips were also inhibited by pinacidil but not by cromakalim. Glibenclamide, a blocker of ATP-regulated K+ (KATP) channels, competitively antagonized the relaxant responses to cromakalim with a pA2 value of 7.62. However, the antagonism by glibenclamide of the relaxant responses to pinacidil was not a typical competitive type, suggesting the contribution of other effects than the KATP channel opening activity to the relaxant effects of pinacidil. In resting strips preloaded with 86Rb, cromakalim and pinacidil increased the basal 86Rb efflux in a dose-dependent manner. The increase in the 86Rb efflux induced by cromakalim was greater than that by pinacidil. When the effects of cromakalim and pinacidil on the 86Rb efflux were determined in the 20.9 or 65.9 mM K(+)-contracted strips, both drugs increased the 86Rb efflux. Under the same conditions nifedipine, a Ca(+)+ channel blocker, produced the relaxation that is accompanied by the decrease in 86Rb efflux. The increase in the 86Rb efflux induced by cromakalim was much greater than that by pinacidil
Ba2+-inhibitable 86Rb+ fluxes across membranes of vesicles from toad urinary bladder
86Rb+ fluxes have been measured in suspensions of vesicles prepared from the epithelium of toad urinary bladder. A readily measurable barium-sensitive, ouabain-insensitive component has been identified; the concentration of external Ba2+ required for half-maximal inhibition was 0.6 mM. The effects of externally added cations on 86Rb+ influx and efflux have established that this pathway is conductive, with a selectivity for K+, Rb+ and Cs+ over Na+ and Li+. The Rb+ uptake is inversely dependent on external pH, but not significantly affected by internal Ca2+ or external amiloride, quinine, quinidine or lidocaine. It is likely, albeit not yet certain, that the conductive Rb+ pathway is incorporated in basolateral vesicles oriented right-side-out. It is also not yet clear whether this pathway comprises the principle basolateral K+ channel in vivo, and that its properties have been unchanged during the preparative procedures. Subject to these caveats, the data suggest that the inhibition by quinidine of Na+ transport across toad bladder does not arise primarily from membrane depolarization produced by a direct blockage of the basolateral channels. It now seems more likely that the quinidine-induced elevation of intracellular Ca2+ activity directly blocks apical Na+ entry
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...
Erythrocyte sodium concentration and 86Rb uptake in weanling Dahl rats
Alterations in Na, K ATPase pump activity as well as erythrocyte (RBC) intracellular sodium concentration (Nai) have been demonstrated in humans and rats with established hypertension. The contribution of hypertension itself to these changes is unclear. Accordingly, we investigated RBC ion transport and plasma ouabain-like factor (OLF) in four- to five-week old normotensive Dahl salt-sensitive (DS) and salt-resistant (DR) rats on low salt diet. Although both strains were normotensive, systolic blood pressure (SBP) of DS (123 ± 2 mm Hg) was higher than that of DR (116 ± 1 mm Hg). No interstrain difference was evident in RBC pump activity measured as ouabain-sensitive 86rubidium (86Rb) uptake (DS = 0.277 ± .030 and DR = 0.271 ± .029 mumol/10(9)RBC/h) even though RBC Nai was greater in DS than DR (14.9 ± 2.0 v 10.7 ± 1.0 mEq/L; P less than 0.05). Plasma OLF was higher in DS than DR (28.9 ± 4.7 v 16.5 ± 2.3 pmol/mL; P less than 0.05), but did not correlate with RBC pump activity in either strain. RBC Nai was directly correlated with pump activity in DS (r = 0.84, P less than 0.01) and demonstrated a trend to correlate in DR (r = 0.71, P = 0.07). RBC Nai was also directly correlated with SBP in DR (r = 0.73, P less than 0.05) and DS (r = 0.70, P = 0.05). We conclude that RBC Nai is genetically determined in Dahl rats and is elevated in normotensive DS who are at risk for hypertension development
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.
Alfalfa (Medicago sativa L.) plants susceptible (S) and resistant (R) to bacterial wilt were fed via roots with a nutrient solution labelled with 86Rb+, at different times after inoculation with Corynebacterium insidiosum (McCull.) H.L. Jens. The infection did not affect 86Rb+ uptake per plant in the course of a 14-day-period following inoculation; however, it affected its distribution differently in the S- and the R-plants. 86Rb+ uptake significantly decreased due to the infection in the S-plants on the day 49 after inoculation (a 4-h-exposure to 86Rb+), with the ions more slowly translocated to the shoots in diseased S-plants than in diseased R-plants. Likely factors causing these effects and their relationship to alfalfa resistance to bacterial wilt are discussed. (author)
Effect of ultraviolet radiation on accumulation and leakage of 86Rb+ in guard cells of Vicia faba
The effects of UV-C (254 nm), UV-A (365 nm) and broad-band UV (280–380 nm) on guard cells of Vicia faba L. cv. Long Pod were investigated in the presence of white light (450 μmol m−2 s−1). UV-C (7 μmol m−2 s−1) was found to cause leakage of 86Rb+ from guard cells, while UV-A (0.3 μmol m−2 s−1) stimulated increased uptake in these cells. A relatively small stimulatory effect was observed by broad-band UV (3 μmol m−2 s−1) during the first 30 min of irradiation with an apparent equilibration of influx and efflux thereafter. Leakage of 86Rb+ from guard cells continued despite the removal of UV-C and an increase in the amount of white light from 450 to 1500 μmol m−2 s−1, suggesting that membranes were irreversibly damaged. Irradiation of guard cells with UV-C for 30, 45 and 90 min indicated that these cells began to be affected already by 30 min UV-C irradiation. (author)
The effect of chronic hypobaric hypoxia equivalent to a simulated high altitude of 4000 m was investigated on the Ca2+ and Rb+ uptake in vascular smooth muscle. The decline in systolic blood pressure in SHR due to hypoxia was associated with a significant decrease in 45Ca uptake and ouabain-insensitive 86Rb uptake as well as the tissue Ca2+ and K+ content. It seems likely that the reduction of the higher vascular tone in SHR by chronic hypoxia is due to the alteration of the transmembrane ion fluxes in the vascular smooth muscle cells. However, the meaning and the nature of the active and passive ion fluxes involved in this problem remains to be clarified. (author)
The effect of sodium ions on the light-induced 86Rb release from the isolated crayfish retina
The effect of low external Na+ concentrations on the light-induced K+ release from crayfish photoreceptor cells was tested by labelling intracellular K+ with the isotope 86Rb. The amount of isotope released per light, stimulus is roughly proportional to the external Na+ concentration if the osmolarity is kept constant by replacing Na+ with Tris, choline or sucrose. When sucrose is used to replace the depleted Na+ the light-induced K+ release is a linear function of the external Na+ concentration and is reduced by approx. 95% at an external Na+ concentration of 5 mmol/l. For choline and Tris substitutions the relationships are less clear but at Na+ concentrations + release is smaller in a Tris solution and larger in a choline solution. It is suggested that the light-induced K+ release is due mainly to an activation of voltage sensitive K+ channels. (orig.)
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)
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.
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.
Neutron reactions with nuclei in isomeric states
The authors give theoretical calculation results for the cross-sections of reactions (n,n'γ) and (n,2n) with high-spin target nuclei in the excited state. It is shown that an increase in the target nucleus excitation energy shifts the cross-section curve to the left along the energy axis, while an increase in the ground state spin considerably reduces the (n,2n) reaction cross-section in the threshold region of the reaction. In the authors' opinion, this change in the excitation functions is due to a sharp rise in the role of gamma competition because of the effect of the spin conservation law on neutron emission. (author)
Transitions between compound states of spherical nuclei
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
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.
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.
Study of fp States in Nuclei with High Neutron Excess
2002-01-01
Previous results obtained at ISOLDE on GT transitions in n-rich Na and Mg nuclei have shown the sharp decrease of excitation energy for fp states when A$>$29. \\\\ \\\\ Independently, shell model calculations have revealed that the onset of a deformation region near N=20 for Ne, Na and Mg nuclei was related to a sudden transition in the ground state properties with the appearance of a major (sd)$^{-2}$(fp)$^2$ component. \\\\ \\\\ We propose to use the new possibilities of producing and detecting n-rich nuclei to study by $\\gamma$ and n spectroscopy the properties of fp states with different cores: around N=20 (Na, Mg and Al) and N=28 (Ar, K and Ca). In particular, the cases of $^3
Coupled cluster calculations of ground and excited states of nuclei
The standard and renormalized coupled cluster methods with singles, doubles, and noniterative triples and their generalizations to excited states, based on the equation of motion coupled cluster approach, are applied to the He4 and O16 nuclei. A comparison of coupled cluster results with the results of the exact diagonalization of the Hamiltonian in the same model space shows that the quantum chemistry inspired coupled cluster approximations provide an excellent description of ground and excited states of nuclei. The bulk of the correlation effects is obtained at the coupled cluster singles and doubles level. Triples, treated noniteratively, provide the virtually exact description
Structure of superdeformed states in Au-Ra nuclei
Energies of superdeformed states in nuclei around 192Hg are calculated using the Strutinsky shell correction method with an average Woods-Saxon potential and a monopole pairing force. The influence of various terms in the model hamiltonian on the excitation energy of the superdeformed minimum is analysed. The systematics of calculated excitation energies of shape-isomeric minima and barrier heights in even-even Hg-Ra nuclei are given together with predictions for one-quasiparticle band-head energies in odd-A Au, Hg, Tl, Pb and Bi nuclei. Possible occurrence of hyperdeformed states in very neutron-deficient Po-Ra isotopes is investigated. It is shown that the presence of these exotic configurations is strongly related to the magnitude of pairing correlations at strongly elongated shapes. Finally, the role played by reflection-asymmetric deformations at superdeformed shapes is discussed. (orig.)
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
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
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
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
Unstable states produced in collisions among complex nuclei
A theory about resonant elastic dispersion is formulated and the wave function of unstable states associated with the resonances observed in the differential and total sections is studied. The object of this theory is to extend to the elastic collisions among complex nuclei interesting case, the methods and formalism of the dispersion of particles without structure by an external potential, following an idea originally formulated by H. Feshbach. (author)
Separable interactions and excited states in open-shell nuclei
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)
Delta(1232) isobar excitations and the ground state of nuclei
Frick, T; Kaiser, S.; Müther, Herbert; Polls Martí, Artur; Entem, D R; Machleidt, R.
2002-01-01
The influence of $\\Delta$ isobar components on the ground state properties of nuclear systems is investigated for nuclear matter as well as finite nuclei. Many-body wave functions, including isobar configurations, and binding energies are evaluated employing the framework of the coupled-cluster theory. It is demonstrated that the effect of isobar configurations depends in a rather sensitive way on the model used for the baryon-baryon interaction. As examples for realistic baryon-baryon intera...
Cluster structure in highly-excited states of light nuclei
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
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.)
Ground state properties of superheavy nuclei with Z=117 and Z=119
We review the current studies on the ground-state properties of superheavy nuclei. It is shown that there is shape coexistence for the ground state of many superheavy nuclei from different models and many superheavy nuclei are deformed. This can lead to the existence of isomers in superheavy region and it plays an important role for the stability of superheavy nuclei. Some new results on Z=117 and Z=119 isotopes are presented. The agreement between theoretical results and experimental data clearly demonstrates the validity of theoretical models for the ground-state properties of superheavy nuclei
Unified framework for understanding pair transfer between collective states in atomic nuclei
A new interpretation of two-nucleon pair transfer in collective nuclei is presented. It differs from traditional models and unifies, within a consistent framework, the entire range of monopole pair-transfer phenomenology in collective nuclei. This includes the well-known examples of large cross sections to excited 0+ states in phase transitional nuclei, and small ones in many other nuclei, but also predicts large cross sections elsewhere under particular circumstances. These predictions can be tested experimentally.
Gamma transitions between compound states in spherical nuclei
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
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
Nadirbekov, M. S., E-mail: nodirbekov@inp.uz; Yuldasheva, G. A. [Uzbek Academy of Sciences, Institute of Nuclear Physics (Uzbekistan); Denisov, V. Yu. [National Academy of Sciences of Ukraine, Institute for Nuclear Research (Ukraine)
2015-03-15
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 {sup 164}Er, {sup 220}Ra, and {sup 224}Th nuclei; the yrast and first nonyrast bands in the {sup 154}Sm and {sup 160}Gd nuclei; and the yrast, first nonyrast, and second nonyrast bands in the {sup 224}Ra and {sup 240}Pu nuclei are described well on the basis of the proposed model.
Alternating-parity collective states of yrast and nonyrast bands in lanthanide and actinide nuclei
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
Isospin dependence of nucleon correlations in ground-state nuclei
Charity, R.J. [Washington University, Department of Chemistry, St. Louis, Missouri (United States); Dickhoff, W.H. [Washington University, Department of Physics, St. Louis, Missouri (United States); Sobotka, L.G. [Washington University, Department of Chemistry, St. Louis, Missouri (United States); Washington University, Department of Physics, St. Louis, Missouri (United States); Waldecker, S.J. [University of Tennessee, Department of Physics, Chattanooga, Tennessee (United States)
2014-02-15
The dispersive optical model (DOM) as presently implemented can investigate the isospin (nucleon asymmetry) dependence of the Hartree-Fock-like potential relevant for nucleons near the Fermi energy. Data constraints indicate that a Lane-type potential adequately describes its asymmetry dependence. Correlations beyond the mean field can also be described in this framework, but this requires an extension that treats the non-locality of the Hartree-Fock-like potential properly. The DOM has therefore been extended to properly describe ground-state properties of nuclei as a function of nucleon asymmetry in addition to standard ingredients like elastic nucleon scattering data and level structure. Predictions of nucleon correlations at larger nucleon asymmetries can then be made after data at smaller asymmetries constrain the potentials that represent the nucleon self-energy. A simple extrapolation for Sn isotopes generates predictions for increasing correlations of minority protons with increasing neutron number. Such predictions can be investigated by performing experiments with exotic beams. The predicted neutron properties for the double closed-shell {sup 132}Sn nucleus exhibit similar correlations as those in {sup 208}Pb. Future relevance of these studies for understanding the properties of all nucleons, including those with high momentum, and the role of three-body forces in nuclei are briefly discussed. Such an implementation will require a proper treatment of the non-locality of the imaginary part of the potentials and a description of high-momentum nucleons as experimentally constrained by the (e, e' p) reactions performed at Jefferson Lab. (orig.)
F-spin purity of 21+ states in even-even nuclei
A procedure is proposed by which upper limits to the F-spin purity of 21+ states in even-even nuclei can be estimated by an analysis of experimental g-factors. The procedure, applied to 17 nuclei with 46≤Z≤78, shows that Fmax admixture up to 10% are not uncommon. A systematic behavior with Z is also observed
Collective and single particle states in medium mass vibrational nuclei
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
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...
Study of neutron hole states in N=82 nuclei
This research thesis reports a systematic investigation of neutron holes in the N=82 closed layer by means of the pick-up (p,d) reaction at 24,55 MeV on Ba-138, Ce-140, Nd-142 and Sm-144, leading respectively to N=81 nuclei of Ba-137, Ce-139, Nd-141 and Sm-143. Angular distributions are compared with predictions obtained by computation based on distorted waves and performed with the DWUCK software. Spectroscopic factors are obtained from this comparison. The author first describes the experimental installation, reports the distorted-wave analysis, and finally presents and discusses the obtained results
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
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.
Recent results at ultrahigh spin: Terminating states and beyond in mass 160 rare-earth nuclei
A classic region of band termination at high spin occurs in rare-earth nuclei with around ten valence nucleons above the 146Gd closed core. The results are presented here for such non-collective oblate (γ = 60°) terminating states in odd-Z 155Ho, odd-odd 156Ho, and even-even 156Er, where they are compared with neighboring nuclei. In addition to these particularly favoured states, the occurrence of collective triaxial strongly deformed (TSD) bands, bypassing the terminating states and extending to over 65ℎ, is reviewed
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.
Regular structure of low-lying states for atomic nuclei under random interactions
In this paper we review regularities of low-lying states for many-body systems, in particular, atomic nuclei, under random interactions. We shall discuss the famous problem of spin zero ground state dominance, positive parity dominance, collective motion, odd-even staggering, average energies, etc., in the presence of random interactions. (author)
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.
High spin states in transitional nuclei in the IBM + broken pair model
For odd-A nuclei the IBFM plus broken pairs describes one and three-fermion states. The model has been applied to the description of high-spin states in the Hg, Sr-Zr and Nd-Sm regions. Calculated spectra and transition probabilities are compared with the experimental data
Inelastic scattering to collective states in double-magic nuclei
The paper discusses several aspects of inelastic scattering to collective states in the framework of the 'Shell Model RPA Approximation' with special emphasis on the analysis of giant resonance states. (orig./WL)
Study of low-lying states via EC/β+ decay for medium-heavy nuclei
Our previous experimental method and results of (EC+β+) decay for the medium-heavy nuclei 153Er, 157Yb, 209Fr, 128Ce, 130Ce, 128Pr, 130Pm and 140Tb have been briefly summarized. The observed low-lying states in their daughter nuclei and a 1 1/2- isomeric state in 133Pr have been reviewed in a systematic way and compared with different model calculations. Finally, some questions have been put forward for further study and discussion. (author)
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
Population and particle decay of isobaric analog states in medium heavy nuclei
The systematic features of proton stripping and neutron pickup reactions to Isobaric Analog States in medium heavy nuclei are presented. The (3He, d) reaction investigated at high incident energy is shown to selectively excite high-spin particle-analog states. Similarly the (3He, α) reaction populates hole-analog states. The recent results related to such highly excited states in a wide range of nuclei (48Ca to 208Pb) are discussed in the framework of the DWBA theory of direct reactions with special emphasis on the treatment of unbound proton states or deeply-bound neutron hole states. The particle decay of Isobaric Analog States are investigated using the (3He, d p tilde) and (3He, α p tilde) sequential processes. The experimental method developed at Orsay (00 detection) for particle-particle angular correlations is presented. The advantage and the limits of such approach are illustrated by typical exemples of particle decays: core-excited states, neutron particle-hole multiplets and the first observation of the proton emission of hole-analog levels. In conclusion new experimental approaches such as asymmetry measurements for analog states observed in transfer reactions or possible population of double analog states in heavy nuclei are discussed. (author)
Open-shell nuclei and excited states from multireference normal-ordered Hamiltonians
Gebrerufael, Eskendr; Calci, Angelo; Roth, Robert
2016-03-01
We discuss the approximate inclusion of three-nucleon (3 N ) interactions into ab initio nuclear structure calculations using a multireference formulation of normal ordering and Wick's theorem. Following the successful application of single-reference normal ordering for the study of ground states of closed-shell nuclei, e.g., in coupled-cluster theory, multireference normal ordering opens a path to open-shell nuclei and excited states. Based on different multideterminantal reference states we benchmark the truncation of the normal-ordered Hamiltonian at the two-body level in no-core shell-model calculations for p -shell nuclei, including 6Li,12C, and 10B. We find that this multireference normal-ordered two-body approximation is able to capture the effects of the 3 N interaction with sufficient accuracy, both for ground-state and excitation energies, at the computational cost of a two-body Hamiltonian. It is robust with respect to the choice of reference states and has a multitude of applications in ab initio nuclear structure calculations of open-shell nuclei and their excitations as well as in nuclear reaction studies.
The ground state of medium-heavy nuclei with non central forces
A. FabrociniINFN and Phys.Dept., Univ.of Pisa, Pisa, Italy
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 i...
Model for asymptotic D-state parameters of light nuclei: application to 4 He
A simple method for calculating the asymptotic D state observables for light nuclei is suggested. The method exploits the dominant clusters of the light nuclei. The method is applied to calculate the 4 He asymptotic D to S normalization ratio ρα and the closely related D state parameter Dα2. The study predicts a correlation between Dα2 and Bα, and between ρα and Bα, where Bα is the binding energy of 4 He. The present study yields ρα ∼ -0.14 and Dα2 ∼ -0.12 fm2 consistent with the correct experimental ηD and the binding energies of the deuteron, triton, and the α particle where ηd is the deuteron D state to S state to S state normalization ratio. (author)
Particle-hole description of GDR states in light nuclei with closed shells +- 2 nucleons
The particle-hole model is presented for nuclei with closed core +- 2 nucleons. The model, as applied to 6Li, 14N, 14C and 18O, gives overall agreement with experiment for the low-lying and GDR states
Mass formula for T = 0 and T = 1 ground states of N = Z nuclei
An algebraic model is developed to calculate the T = 0 and T = 1 ground-state binding energies for N = Z nuclei. The method is tested in the sd shell and is then extended to the 28-50 shell which is currently the object of many experimental studies. (authors)
Pairing and high-spin states in proton-rich N =82 nuclei
Andreozzi, F.; Covello, A.; Gargano, A.; Porrino, A. (Dipartimento di Scienze Fisiche, Universita di Napoli Federico II, Istituto Nazionale di Fisica Nucleare, Mostra d' Oltremare, Pad. 20, 80125 Napoli (Italy))
1992-04-01
This paper is an extension of a previous study of the pairing effects in the {ital N}=82 isotones. It is concerned with high-spin states in the nuclei from {sup 146}Gd through the recently explored {sup 153}Lu and {sup 154}Hf. The results obtained confirm the importance of proton pairing correlations in the {ital N}=50--82 shell.
State-dependent pairing fields in rotating nuclei
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
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.)
Effects of Beta-Decays of Excited-State Nuclei on the Astrophysical r-Process
Famiano, M A; Kajino, T; Otsuki, K; Terasawa, M; Mathews, G J
2008-01-01
A rudimentary calculation is employed to evaluate the possible effects of beta- decays of excited-state nuclei on the astrophysical r-process. Single-particle levels calculated with the FRDM are adapted to the calculation of beta-decay rates of these excited-state nuclei. Quantum numbers are determined based on proximity to Nilson model levels. The resulting rates are used in an r-process network calculation in which a supernova hot-bubble model is coupled to an extensive network calculation including all nuclei between the valley of stability and the neutron drip line and with masses A<284. Beta-decay rates are included as functional forms of the environmental temperature. While the decay rate model used is simple and phenomenological, it is consistent across all 3700 nuclei involved in the r-process network calculation. This represents an approximate first estimate to gauge the possible effects of excited-state beta-decays on r-process freeze-out abundances.
Studies of K-absorption on light nuclei and the search for bound nuclear kaonic states
The available experimental data on K-absorption on nuclei are rather old and scarce: they are not enough to understand the possible formation of aggregates of nucleons bound together by a kaon, known as 'Bound Kaonic Nuclear States'. The existence of such structures, suggested by a few theoretical models, has not been experimentally ascertained yet. To be observed, their width should be less than their binding energy. A possible decay channel for such states is the non mesonic one, leading to hyperon-nucleon (or light nuclei) final states. Therefore, experimental investigations of possible signatures are mainly based on the analysis of hyperon-nucleon(s) correlations (for instance, of Λp(d,t) pairs) and of invariant mass spectra. Complementary information may also be gathered from missing mass distributions. Recent experiments revived, with much larger statistics, the study of K-A absorption in light nuclei: namely, KEK-E549 studied the K-interactions on 4He, while FINUDA at DAΦNE collected a large statistics on K-6,7Li, K-9Be and K-12C. The experimental results obtained so far by the various experiments studying the K-absorption in nuclei are here summarized.
Potentials for calculating both parity states in p-shell nuclei
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
Quasiparticle and quasihole states of nuclei around 56Ni
The single-particle spectral function of 56Ni has been computed within the framework of self-consistent Green's functions theory. The Faddeev random phase approximation method and the G matrix technique are used to account for the effects of long- and short-range physics on the spectral distribution. Large-scale calculations have been performed in spaces including up to ten oscillator shells. The chiral N3LO interaction is used together with a monopole correction that accounts for eventual missing three-nucleon forces. The single-particle energies associated with nucleon transfer to valence 1p0f orbits are found to be almost converged with respect to both the size of the model space and the oscillator frequency. The results support that 56Ni is a good doubly magic nucleus. The absolute spectroscopic factors to the valence states on A=55,57 are also obtained. For the transition between the ground states of 57Ni and 56Ni, the calculations nicely agree with heavy-ion knockout experiments.
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...
The influence of s states near threshold on the structure of light nuclei
Hoffman, Calem
2015-10-01
A recent work identified the role of neutron s states, and their proximity to the neutron separation threshold, on the ordering of the 1s1 / 2 and 0d5 / 2 single-particle levels in light nuclei. A simple Woods-Saxon potential was used to reproduce the systematic data available for these two levels with great success by accounting for the s state binding energy. This talk will explore other noticeable trends in light nuclei involving neutron s states and utilizing simple potential models determine the role binding energy plays. The trends and calculations will aim to provide descriptions of data and predictions of yet to be found two-particle two-hole excited states in N = 8 and 10 nuclei ranging from Z = 4-9, as well as the energies of mirror states in neutron deficient Al and Na isotopes. Results will be compared with state-of-the-art calculations. Possible future measurements capable of probing these predictions will be discussed as well. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, under Contract Number DE-AC02-06CH11357.
Spectroscopy of high-lying states in actinide nuclei
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.
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...
Proton Single-Particle States In The Heaviest Actinide Nuclei
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
Open-Shell Nuclei and Excited States from Multi-Reference Normal-Ordered Hamiltonians
Gebrerufael, Eskendr; Roth, Robert
2015-01-01
We discuss the approximate inclusion of three-nucleon interactions into ab initio nuclear structure calculations using a multi-reference formulation of normal ordering and Wick's theorem. Following the successful application of single-reference normal ordering for the study of ground states of closed-shell nuclei, e.g., in coupled-cluster theory, multi-reference normal ordering opens a path to open-shell nuclei and excited states. Based on different multi-determinantal reference states we benchmark the truncation of the normal-ordered Hamiltonian at the two-body level in no-core shell-model calculations for p-shell nuclei, including 6-Li, 12-C, and 10-B. We find that this multi-reference normal-ordered two-body approximation is able to capture the effects of the 3N interaction with sufficient accuracy, both, for ground-state and excitation energies, at the computational cost of a two-body Hamiltonian. It is robust with respect to the choice of reference states and has a multitude of applications in ab initio ...
Multiphonon method applied to vibrational (K=O) state study in deformed heavy nuclei
An explicit formulation of the multiphonon method is given where two phonons are introduced as base. Vibrational states can then be studied in the realistic case of pair deformed heavy-nuclei (plutonium, uranium and thorium isotopes). Localization and properties of two-phonon states are particularly examined. Energy spectra are systematically dilated, octupolar vibrations K=O- show more anharmonicity than the K=O+ ones. The two-phonon states are between 1.7 and 2 MeV; they keep a collective nature by their electromagnetic transitions (E1, E2, E3) towards one-phonon states
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.
Structure of excited states in nuclei near doubly magic 100SN
The three neutron-deficient nuclei 94Pd, 98Cd and 104Sn in the vicinity of 100Sn were investigated by means of in-beam γ-ray spectroscopy of excited states. The isomeric decays in 94Pd and 98Cd were studied for the first time with an exclusive experimental setup for delayed γ-ray detection with complete exit channel identification based on information from neutron and charged-particle filter detectors. The structure of excited states of 94Pd showed the first indication of increasing proton-neutron interaction towards the N=Z line in this region of nuclei, that in turn might be related to increased proton-neutron pairing correlations predicted in Tz=0 nuclei. The closest neighbours of 100Sn with two active particles, 98Cd and 102Sn, are now known with their lowest excited states. The measured reduced transition probabilities for the decay of the isomeric 8+ and 6+ states in 98Cd and 102Sn, respectively, allowed to extract an effective quadrupole charge for neutron and proton in this region of nuclei based on the high configurational purity of the states. While the neutron effective charge appeared to be large and in agreement with expectation, the proton effective charge value is very small (eπ≤1). This controversial result, which would indicate that 100Sn is a very good closed shell nucleus with respect to quadrupole excitation, is not understood. An experimental reason for this result, related to existence of a core excited isomer, observed in the experiment by means of its half life but not γ-rays, which may have escaped observation, can not be definitely excluded and is left as possible explanation. (orig.)
Structure of excited states in nuclei near doubly magic {sup 100}SN
Gorska, M.
1998-11-01
The three neutron-deficient nuclei {sup 94}Pd, {sup 98}Cd and {sup 104}Sn in the vicinity of {sup 100}Sn were investigated by means of in-beam {gamma}-ray spectroscopy of excited states. The isomeric decays in {sup 94}Pd and {sup 98}Cd were studied for the first time with an exclusive experimental setup for delayed {gamma}-ray detection with complete exit channel identification based on information from neutron and charged-particle filter detectors. The structure of excited states of {sup 94}Pd showed the first indication of increasing proton-neutron interaction towards the N=Z line in this region of nuclei, that in turn might be related to increased proton-neutron pairing correlations predicted in T{sub z}=0 nuclei. The closest neighbours of {sup 100}Sn with two active particles, {sup 98}Cd and {sup 102}Sn, are now known with their lowest excited states. The measured reduced transition probabilities for the decay of the isomeric 8{sup +} and 6{sup +} states in {sup 98}Cd and {sup 102}Sn, respectively, allowed to extract an effective quadrupole charge for neutron and proton in this region of nuclei based on the high configurational purity of the states. While the neutron effective charge appeared to be large and in agreement with expectation, the proton effective charge value is very small (e{sub {pi}}{<=}1). This controversial result, which would indicate that {sup 100}Sn is a very good closed shell nucleus with respect to quadrupole excitation, is not understood. An experimental reason for this result, related to existence of a core excited isomer, observed in the experiment by means of its half life but not {gamma}-rays, which may have escaped observation, can not be definitely excluded and is left as possible explanation. (orig.)
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
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.
Systematics of ground state multiplets of atomic nuclei in the delta-interaction approach
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.
Systematics of ground state multiplets of atomic nuclei in the delta-interaction approach
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
Systematics of ground state multiplets of atomic nuclei in the delta-interaction approach
Imasheva, L. T.; Ishkhanov, B. S.; Stepanov, M. E.; Tretyakova, T. Yu.
2015-12-01
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.
Study of ground and excited state decays in N ≈ Z Ag nuclei
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.
Excited states in the neutron deficient nuclei 138Sm and 139Eu
Excited states in the two N=76 nuclei 138Sm and 139Eu have been identified via 32S induced reactions on different targets using γ-ray spectroscopy methods. Lifetimes have been measured with the Doppler shift recoil distance technique, showing the coexistence of a large nuclear deformation (β-0.24) with excitations of single particle character. The E2 transition strengths in the odd-even nucleus 139Eu and in its core 138Sm are discussed. (orig.)
Properties of the lowest negative parity states in N= 82 magic nuclei
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.
Q-phonon approach for low lying dipole two-phonon states in spherical nuclei
The properties of 1- two-phonon states and the characteristics of E1 transition probabilities between low-lying collective states in spherical nuclei were analyzed within the Q-phonon approach to the description of collective states. Several relations between observables were obtained. Microscopic calculations of the E1 01+→11- transition matrix elements were performed on the basis of RPA. A satisfactory description of the experimental data was obtained. The results of the calculations of the electric dipole transition matrix elements are presented
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.
High-Spin States in and Around Doubly-Magic Nuclei
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.
Present status of alpha-particle condensate states in self-conjugate 4n nuclei
Low density states near the 3α and 4α breakup threshold in 12C and 16O, respectively, are discussed in terms of the α-particle condensation. Calculations are performed in OCM (Orthogonality Condition Model) and THSR (Tohsaki-Horiuchi-Schuck-Roepke) approaches. The 02+ state in 12C and the 06+ state in 16C are shown to have dilute density structures and give strong enhancement of the occupation of the S-state c.o.m. orbital of the α-particles. The 06+ state in 16C has a large component of α + 12C(02+) configuration, which is another reliable evidence of the state to be of 4α condensate nature. The possibility of the existence of α-particle condensed states in heavier nα nuclei is also discussed. (author)
Halo Structure of Isobaric Analogue States in A= 21 and 17 Mirror Nuclei
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
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
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.
Izosimov, I. N., E-mail: izosimov@jinr.ru [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation)
2015-10-15
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 {sup 6,7,8}Li, {sup 8,9,10}Be, {sup 8,10,11}B, {sup 10,11,12,13,14}C, {sup 13,14,15,16,17}N, {sup 15,16,17,19}O, and {sup 17}F are analyzed. Special attention is given to nuclei whose ground state does not exhibit halo structure but the excited state may have one.
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
The equation of state of nuclear matter, and nuclei in laboratories and in neutron-star crusts
We examine a relationship between the phenomenological equation of state (EOS) of nuclear matter near normal nuclear density and neutron-rich nuclei in laboratories and in neutron-star crusts. In this study, we use about 200 EOS's, which are systematically constructed in such a way as to provide a reasonable fit to empirical masses and radii of stable nuclei by simplified Thomas-Fermi calculations. As for neutron-rich nuclei in laboratories, matter radii and masses are shown to be functions of the symmetry energy density derivative coefficient L. We also find that the boundary density between the core and crust of neutron stars is a decreasing function of L. We expect that future systematic measurements of the matter radii and masses of neutron-rich nuclei could help deduce the L value, which in turn could give useful information about nuclei in neutron-star crusts. (author)
Gound State Properties of Nuclei in 295118 α-Decay Chain
The properties of nuclei belonging to the α-decay chain of superheavy element 295118 have been studied in the framework of axially deformed relativistic mean field (RMF) theory with the parameter set of NL-Z2 in the blocked BCS approximation. Some ground state properties such as binding energies, deformations, and α-decay energies Qα have been obtained and agree well with those from finite-range droplet model (FRDM). The single-particle spectra of nuclei in 295118 α-decay chain show that the shell gaps present obviously nucleon number dependence. The root-mean-square (rms) radii of proton, neutron and matter distributions change slowly from 283112 to 295118 but dramatically from 279110 to 283112, which may be due to the subshell closure at Z = 110 in 279110. The α-decay half-lives in 295118 decay chain are evaluated by employing the cluster model and the generalized liquid drop model (GLDM), and the overall agreement is found when they are compared with the known experimental data. The α-decay lifetimes obtained from the cluster model are slightly larger than those of GLDM ones. Finally, we predict the α-decay half-lives of Z = 118, 116, 114, 112 isotopes using the cluster model and GLDM, which also indicate these two models can corroborate each other in studies on superheavy nuclei. The results from GLDM are always lower than those obtained from the cluster model. (nuclear physics)
Structure of high spin states of 76Kr and 78Kr nuclei
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.
Alpha cluster states in light nuclei populated through the (6Li,d) reaction
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 (xα) and(xα+ν) nuclei through the (6Li,d) alpha transfer reaction. In fact, there is scarce experimental information on the subject, in particular associated with resonant states predicted near (xα) and (xα+ν) thresholds. Measurements of the 12,13C(6Li,d) 16,17O 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 (4α) breakup threshold in 16O, three narrow alpha resonances, not previously measured, were detected, revealing important α + 12C(G.S.) components. One of these resonances corresponds to the known 0+ state at 15.1 MeV[5] of excitation that has probably, according to Funaki et al., the gas like configuration of the 4α condensate state, with a very dilute density and a large component of α + 12C(Hoyle) configuration. As was already mentioned, our experimental information points to the necessity of including the α + 12C(G.S.) component in the wave function. (author)
Core polarization and 3/2 states of some f-p shell nuclei
The energies, wavefunctions, spectroscopic factors and M1 transition strengths have been calculated for the 3/2- states excited via single proton transfer to 2p3/2 orbit of the target nuclei 50Ti, 52Cr, 54Fe and 56Fe. The calculations have been done by using the Kuo and Brown interaction in the entire four shell space as well as the shrunk Kuo and Brown interaction calculated in (1f7/2-2p3/2) space. The salient feature of the calculation is that whereas the systematics of single particle strength distribution are well reproduced, the energy splitting between the calculated T> centroid and the centroid of T> states is always much smaller than that observed experimentally. It has been found, however, that the modified KB interaction widens the energy gap between the T> centroid and the centroid of T> states without appreciably affecting the final wave-functions. (author)
Study of the giant dipole resonance built on highly excited states in Sn and Dy nuclei
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
Interplay of collective and single-particle states in neutron deficient transitional nuclei
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)
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.
Fermionic structure of collective states of light nuclei and the Dyson boson mapping
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
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.
Contribution of excited states to stellar weak-interaction rates in odd-A nuclei
Sarriguren, P.
2016-05-01
Weak-interaction rates, including β decay and electron capture, are studied in several odd-A nuclei in the p f -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.
Population of Metastable States in Stable Hafnium and Ytterbium Nuclei via Beam Break-up
The ''Chessboard'' section of the DIAMANT charged-particle array has been coupled with the AFRODITE γ-ray spectrometer at the iThemba Laboratory for Accelerator Based Sciences. Charged-particle-γ-ray coincidence data were recorded during the bombardment of a 176Yb target with a 13C beam at an energy of 90 MeV. The purpose of the investigation was to study the population of metastable states in hafium nuclei via incomplete fusion reactions in which the beam breaks up due to its α-cluster character. Of note was the observation of the band based on the Kπ = 16+, T1/2 = 31 year isomer in 178Hf to its 19+ member. Also, decays from the high-K isomeric states in 174Yb and 176Yb. which were populated via 3αxn channels, indicative of complete break-up of the 13C beam
The evaporation residue in the fission state of Barium nuclei within relativistic mean-field theory
Bhuyan, M; Gupta, Raj K
2013-01-01
The evaporation residue of Barium isotopes are investigated in a microscopic study using relativistic mean field theory. The investigation includes the isotopes of Barium from the valley of stability to exotic proton-rich region. The ground as well as neck configurations for these nuclei are generated from their total nucleonic density distributions of the corresponding state. We have estimated the constituents (number of nucleons) in the elongated neck region of the fission state. We found the $\\alpha$-particle as the constituent of neck of Ba-isotopes, referred to as the evaporated residue in heavy-ion reaction studies. A strong correlation between the neutron and proton is observed throughout the isotopic chain.
Correlation of β-band with ground state band in medium mass nuclei
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
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
The proton-neutron degree of freedom in collective states of medium heavy nuclei
In this thesis the collective excitation forms of heavy nuclei are studied in the framework of the interacting boson model (IBM) which was developed by A. Arima and F. Iachello (1984). A description equivalent to the description of the dynamics of the surface is obtained in the IBM by the IBM-1 which not discriminates between protons and neutrons. The introduction of the proton-neutron degree of freedom occurs in the IBM-2 by the introduction of proton and neutron bosons. It is an essential aim of the present thesis to explain the apparent contradiction between the dominance of the proton-neutron interaction (IBM-2) and the phenomenological description power of the IBM-1 respectively to draw consequences from this. An essential mean for this is the introduction of the F spin which allows there application of the SU(2) group to the study of the Hamiltonian on its properties in connection with the proton-neutron exchange symmetry. The M1-transitions were used in order to study the purity of the F spin. In this connection the collective states of the nuclei 128Xe and 168Er could be consistently described in the energies, the B(E2) and the M1-transitions. (orig./HSI)
Alpha cluster states in light nuclei populated through the (6Li,d) reaction
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)
Investigation of the structure of the intermediate-energy excited states of the deformed nuclei
This paper reports that at present, the comprehensive experimental information is available on the properties of low-lying states of atomic nuclei which allows one to describe on a microscopic level the basic regularities of their simplest excitations. The use of the neutron spectroscopy methods formed the experimental basis for studying complex highly excited states lying with a high density in the nucleon binding energy region. They are mainly described in the framework of the statistical approach. At the same time, the study of the transitional region of intermediate excitation (3 MeV approx-lt E approx-lt Bn) has not long ago been undertaken. These states are very complicated in structure and their density is so high that the traditional experimental methods of studying and microscopic describing nuclear states developed for the low-energy regions turned out to be ineffective and inapplicable. The statistical methods also cannot describe to the full the properties of intermediate states since, as experiment shows, different structural effects arise systematically in this energy region
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.)
Particle-number conserving treatment for the ground state bands in even-even transfermium nuclei
The ground state bands observed in even-even transfermium nuclei 250Fm and 252,254No are investigated by the cranked shell model with the particle-number conserving treatment for the monopole and quadrupole pairing correlations. The experimental variations of the kinematic moment of inertia with rotational frequency are reproduced very well in our calculation. Our results show backbendings of ℑ(1) at ħω ≈ 0.275 and 0.300 MeV in 252No and 254No, respectively. The detailed information about the contribution to alignment from each cranked single particle level exhibits that the backbending is mainly due to the rapidly aligned angular momentum of proton 1j15/2 [770]1/2 pairs and neutron 2h11/2 [761]3/2, 1j15/2 [734]9/2 pairs the band crossing. (author)
Study of particle unbound states in 25Mg and 25Al nuclei by the reaction 24Mg(d,pn)
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
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
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.
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.
Sharma, Natasha
2016-01-01
The excellent particle identification capabilities of the ALICE detector, using the time projection chamber and the time-of-flight detector, allow the detection of light nuclei and anti-nuclei. Furthermore, the high tracking resolution provided by the inner tracking system enables the separation of primary nuclei from those coming from the decay of heavier systems. This allows for the reconstruction of decays such as the hypertriton mesonic weak decay ($^3_{\\Lambda}$H$\\rightarrow ^3$He + $\\pi^-$), the decay of a hypothetical bound state of a $\\Lambda$n into a deuteron and pion or the H-dibaryon decaying into a $\\Lambda$, a proton and a $\\pi^{-}$. An overview of the production of stable nuclei and anti-nuclei in proton-proton, proton-lead and, in particular, lead-lead collisions is presented. Hypernuclei production rates in Pb--Pb are also shown, together with the upper limits estimated on the production of hypothetical exotica candidates. The results are compared with predictions for the production in thermal...
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
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.
Superdeformation was first proposed some twenty years ago to explain the fission isomers observed in some actinide nuclei. It was later realized that superdeformed shapes can occur at high angular momentum in lighter nuclei. The interest in the mechanisms responsible for these exotic shapes has increased enormously with the discovery of a superdeformed band of nineteen discrete lines in 152Dy (8). At about the same time, evidence for highly deformed nuclei (axis ratio 3:2) was also reported near 132Ce(9). Striking properties emerged from the first experiments, such as the essentially constant energy spacing between transitions (picket-fence spectra), the unexpectedly strong population of superdeformed bands at high spins, and the apparent lack of a link between the superdeformed states and the yrast levels. These findings were reviewed by Nolan and Twin. The present article follows upon their work and discusses the wealth of information that has since become available. This includes the discovery of a new island of superdeformation near A = 190, the detailed spectroscopy of ground and excited bands in the superdeformed well near A = 150 and A = 190, the surprising occurrence of superdeformed bands with identical transition energies in nuclei differing by one or two mass units, and the improved understanding of mechanisms responsible for the feeding into and the decay out of the superdeformed states
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 ...
Alpha-decays to members of ground-state rotational band of heavy even-even nuclei
We apply a simple barrier penetration approach to calculate α-decay branching ratios to members of ground-state rotational band of heavy even-even nuclei. The influence of α-decay energy, the angular momentum of α-particle, and the excitation probability of the daughter nucleus is taken into account in our calculations. The theoretical branching ratios of α-transitions are found to agree with the available experimental data well. (author)
Projected Shell Model Study of Yrast States of Neutron-Deficient Odd-Mass Pr Nuclei
Ibanes, A. [Instituto de Fisica, Mexico; Ortiz, Mark E [ORNL; Velazquez, V. [Universidad Nacional Autonoma de Mexico (UNAM); Galindo-Uribarri, Alfredo {nmn} [ORNL; Hess, P. O. [Universidad Nacional Autonoma de Mexico (UNAM); Sun, Y. [Shanghai Jiao Tong University, Shanghai
2011-01-01
A wide variety of modern instruments allow us to study neutron-deficient nuclei in the A = 130 mass region. Highly deformed nuclei have been found in this region, providing opportunities to study the deformed rotational bands. The description of the 125,127,129,131,133Pr isotopes with the projected shell model is presented in this paper. Good agreement between theory and experiment is obtained and some characteristics are discussed, including the dynamic moment of inertia J (2), kinetic moment of inertia J (1), the crossing of rotational bands, and backbending effects.
Projected shell model study of yrast states of neutron-deficient odd-mass Pr nuclei
A wide variety of modern instruments allow us to study neutron-deficient nuclei in the A=130 mass region. Highly deformed nuclei have been found in this region, providing opportunities to study the deformed rotational bands. The description of the 125,127,129,131,133Pr isotopes with the projected shell model is presented in this paper. Good agreement between theory and experiment is obtained and some characteristics are discussed, including the dynamic moment of inertia J(2), kinetic moment of inertia J(1), the crossing of rotational bands, and backbending effects.
Contribution to the study of collective states of heavy nuclei by means of coulomb excitation
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)
A method is proposed for simultaneously determining the interval of the most probable values of the density of levels excited in the radiative capture of slow neutrons and the sum of radiative E1 and M1 strength functions in the excitation-energy interval extending nearly up to the neutron binding energy. Experimental data on the intensities of two-step photon cascades between the compound state and a given low-lying level of the nucleus being studied are analyzed together with the total radiative widths of neutron resonances. Such an analysis can be performed for nuclei having an arbitrary level density, including deformed ones. The resulting data demonstrate that there are significant deviations from the predictions of commonly accepted level-density models--for example, the Fermi gas model--and specify the range of nuclei and the regions of their excitation energies where a further experimental investigation can furnish new important information about the properties of nuclear matter
Cascade. gamma. -decay of compound state of the nuclei /sup 163/Dy, /sup 167/Er and /sup 179/Hf
Boneva, S.T.; Khitrov, V.A.; Popov, Yu.P.; Sukhovoj, A.M.; Vasilieva, E.V.; Yazvitsky, Yu.S.
1988-06-01
An attempt has been made to reveal the general characteristics of two-quanta cascades, populating the low-lying states of an excitation energy < or approx.1 MeV. The difference observed between the experimental cascade intensities and statistical model calculations has been analysed. Qualitative explanation of the measured two-quanta cascade intensities was achieved in the framework of a quasi-particle phonon model description of highly excited states. A considerable enhancement was revealed of the radiative strength function of the E2-transitions in the studied nuclei.
Cascade γ-decay of compound state of the nuclei 163Dy, 167Er and 179Hf
An attempt has been made to reveal the general characteristics of two-quanta cascades, populating the low-lying states of an excitation energy < or approx.1 MeV. The difference observed between the experimental cascade intensities and statistical model calculations has been analysed. Qualitative explanation of the measured two-quanta cascade intensities was achieved in the framework of a quasi-particle phonon model description of highly excited states. A considerable enhancement was revealed of the radiative strength function of the E2-transitions in the studied nuclei. (orig.)
Grzywacz, R. [Warsaw Univ. (Poland)]|[Grand Accelerateur National d`Ions Lourds (GANIL), 14 - Caen (France); Anne, R.; Auger, G.; Corre, J.M. [Grand Accelerateur National d`Ions Lourds (GANIL), 14 - Caen (France); Borcea, C. [Institute of Atomic Physics, Bucharest (Romania); Doerfler, T. [Goettingen Univ. (Germany); Fomichov, A. [Joint Inst. for Nuclear Research, Dubna (Russian Federation); Grevy, S.; Guillemaud-Mueller, D. [Paris-11 Univ., 91 - Orsay (France). Inst. de Physique Nucleaire; Huyse, M. [Louvain Univ. (Belgium). Inst. for Nuclear- and Radiationphysics; and others
1996-09-01
Correlation between detected ions and following gamma decay of the {mu}s isomeric state provides for unambiguous identification of the nuclei implanted at the final focus of projectile fragment separators. (K.A.). 5 refs.
Microscopic structure of high-spin vibrational states in superdeformed A=190 nuclei
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.
Improvement of sensitivity and resolution of solid state NMR for quadrupolar nuclei
In NMR measurements of quadrupolar nuclei, the spectral analysis has troublesome because of large line width of NMR peak that is caused by second-order quadrupolar interaction. As a result of application of MQMAS to structural analyses of coal and clay minerals, the substantial increase of spectral resolution archived has enabled us to elucidate their fine chemical structures. On the other hand, we have addressed establishment of STMAS method, because sensitivity of MQMAS is too low to perform the analysis of trace amounts of elements. A new developed NMR probe with feature of very precise adjustment of magic angle, which is critical in STMAS, has attained sensitivity enhancement of up to approximately 5 times compared to MQMAS. Since sensitivity and resolution of these methods are furthermore improved by the combination with high magnetic field strength, their application are promised for low-sensitive nuclei and low-level elements, which have been regarded as quite difficult to measure. (author)
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...
The reduced transition probabilities for excited states of rare-earths and actinide even-even nuclei
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
Nuclear structure studies in the A approx. 150 region by γ-ray spectroscopy following heavy ion induced reactions are summarized. Yrast states of N = 82 nuclei close to the proton drip line have been identified as rather pure (πh/sub 11/2)/sup n/ excitations of seniority 2 and 3. The high-spin level structure of 154Dy has been determined through the 124Sn(34S,4nγ) reaction. Both the structure and the level lifetimes indicate a transition at I approx. 32 from collective to few-particle character, with possible shape changes from prolate-to-triaxial-to-oblate
Search for mixed-symmetry states of nuclei in the vicinity of the double-magic nucleus 208Pb
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.
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
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.
Regan, P. H.
2015-11-01
Precision measurements of electromagnetic transition rates provide accurate inputs into nuclear data evaluations and are also used to test and validate predictions of state of the art nuclear structure models. Measurements of transition rates can be used to ascertain or rule out multipolarity assignments for the measured EM decay, thereby providing spin- and parity-difference information for states between which the EM transition takes place. This conference paper reports on a measurements of electromagnetic transition rates between excited nuclear states using coincidence `fast-timing' gamma-ray spectroscopy with cerium-doped, lanthanum-tribromide (LaBr3(Ce)) detectors. Examples of recent precision measurements using a combined LaBr3-HpGe array based at the tandem accelerator, Bucharest, Romania include studies around the N=20 and N=82 shell closures using stable-beam induced fusion-evaporation reactions; and the evolution of nuclear deformation around in neutron-rich Hf, W and Os nuclei using 7Li-induced light-ion transfer reactions. This paper also presents the ongoing development of a new multidetector LaBr3(Ce) array for future studies of exotic nuclei produced at the upcoming Facility for Anti-Proton and Ion Research (FAIR) as part of the NUSTAR-DESPEC project, and reports on the pre-NUSTAR implementations of detectors from this array to study electromagnetic transition rates in neutron-rich fission fragments at ILL-Grenoble, France and RIBF at RIKEN, Japan.
Isospin Symmetry of Odd-Odd Mirror Nuclei: Identification of Excited States in N=Z-2 48Mn
Excited states have been observed in the N=Z-2 odd-odd nucleus 48Mn for the first time. Through comparison with the structure of 48V, a first high-spin study of an odd-odd mirror pair has been achieved. Differences between the T=1 analogue states in this pair have been interpreted in terms of Coulomb effects, with the aid of shell-model calculations in the full pf valence space. Unlike other mirror pairs, the energy differences have been interpreted almost entirely as due to a monopole effect associated with smooth changes in radius (or deformation) as a function of angular momentum. In addition, the large energy shift between analogue negative-parity states is interpreted in terms of the electromagnetic spin-orbit interaction in nuclei
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
A test experiment for the study of excited states in Z≅56, N≅80 nuclei via deep inelastic reactions
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
Zdunczuk, H; Dobaczewski, J; Kosmulski, M
2007-01-01
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 1D cranked state constrained to the average spin projection of =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.
Patra, S K; Centelles, M; Viñas, X
2001-01-01
Binding energies, quadrupole deformation parameters, spins and parities of the neutron-deficient odd $Z=N+1$ nuclei in the $A\\sim 80$ region are calculated in the relativistic mean field approximation. The ground-state and low-lying configurations of the recently observed $^{77}$Y, $^{79}$Zr and $^{83}$Mo nuclei are analyzed. The calculated results are compared with other theoretical predictions.
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...
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.
The spontaneous fission half-lives for heavy and superheavy nuclei between U and Hs isotopes are calculated in framework of the generalized liquid drop model by applying a new method of numerically solving Schrödinger equation compared with the semi-empirical WKB approximation. The calculated half-lives are in very good agreement with the experimental data, indicating the reliability of the new approach. The second part of this work is to estimate the fission half-lives of 238Np⁎ at excited state of 7.3 MeV and 239U⁎ at excited states of 7.081, 8.078, 8.387 and 8.989 MeV with the numerical method. The estimated results compared with the experimental values and with the results by WKB approximation show the numerical method is applicable to both the spontaneous fission and excited fission
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.
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
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.
Dogonowski, Anne-Marie; Siebner, Hartwig R; Sørensen, Per Soelberg;
2013-01-01
matched 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...
It has been shown previously that, below a critical angular momentum, yrast bands of non-magic nuclei are well described by the two-parameter variable moment of inertia model. Some striking exceptions to this rule are found in nuclei which have the same mass number as doubly magic nuclei but possess either one (or two) proton pairs beyond a magic number and one (or two) neutron hole pairs, or vice versa. Yrast bands in these 'pseudomagic' nuclei resemble those in magic nuclei. (author)
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 187,189Bi 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 187,189Bi 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)
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)
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
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)
The All Sky Monitor (ASM) on board the Rossi X-ray Timing Explorer has continuously monitored a number of active galactic nuclei (AGNs) with similar sampling rates for 14 years, from 1996 January to 2009 December. Utilizing the archival ASM data of 27 AGNs, we calculate the normalized excess variances of the 300-day binned X-ray light curves on the longest timescale (between 300 days and 14 years) explored so far. The observed variance appears to be independent of AGN black-hole mass and bolometric luminosity. According to the scaling relation of black-hole mass (and bolometric luminosity) from galactic black hole X-ray binaries (GBHs) to AGNs, the break timescales that correspond to the break frequencies detected in the power spectral density (PSD) of our AGNs are larger than the binsize (300 days) of the ASM light curves. As a result, the singly broken power-law (soft-state) PSD predicts the variance to be independent of mass and luminosity. Nevertheless, the doubly broken power-law (hard-state) PSD predicts, with the widely accepted ratio of the two break frequencies, that the variance increases with increasing mass and decreases with increasing luminosity. Therefore, the independence of the observed variance on mass and luminosity suggests that AGNs should have soft-state PSDs. Taking into account the scaling of the break timescale with mass and luminosity synchronously, the observed variances are also more consistent with the soft-state than the hard-state PSD predictions. With the averaged variance of AGNs and the soft-state PSD assumption, we obtain a universal PSD amplitude of 0.030 ± 0.022. By analogy with the GBH PSDs in the high/soft state, the longest timescale variability supports the standpoint that AGNs are scaled-up GBHs in the high accretion state, as already implied by the direct PSD analysis.
Effect of phonon interaction on the ground state of even-even spherical nuclei
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
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
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...
Miyazawa, Hideyuki; Tanaka, Hajime
2007-07-01
It is a fundamental physical problem how a state is selected in a nonequilibrium steady state where the energy is continuously dissipated. This problem is common to phase transitions in liquids under shear flow and those in solids under deformation or electric current. In particular, soft matter often exhibits a strong nonlinear response to an external field, since its structural susceptibility to the external field is extremely large due to its softness and flexibility. Here we study the nucleation and growth process of the lamellar phase from the sponge phase under shear flow in a bilayer-forming surfactant system. We found an interesting shape selection of lamellar nuclei under shear flow between multilamellar vesicles (onions) and cylinders (leeks). These two types of behavior are separated sharply at a critical shear rate: a slight change of the shear rate is enough to switch one behavior to the other. We also found that, under a sufficiently strong shear flow, nucleated onions decrease their size with time, and eventually transform into leeks. This suggests that leeks may be the stable morphology under steady shear flow. However, the stability is limited only to the lamellar-sponge coexistence region. When a system enters into the lamellar phase region by further cooling, leeks lose their stability and break up into rather monodisperse onions, presumably via Rayleigh-like instability of a fluid tube. On the basis of these results, we draw a dynamic state diagram of smectic membrane organization under shear flow.
Yoshinaga, N.; Arima, A.; Zhao, Y. M.
2006-01-01
In this report we study the origin of spin-zero ground-state dominance for even-even nuclei in the presence of random two-body interactions. We evaluate the ground-state energy in terms of the energy centroid and the width of the random Hamiltonian. For both fermions and bosons in a single orbital, we obtain excellent agreement between the spin-I ground state probabilities predicted by using our formula and those obtained by diagonalizing the random Hamiltonian.
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...
Study of some excited states in 21Ne-21Na, 18O-18F and 15N-15O nuclei
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
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
A MAG spectrometer is designed to analyze kinematics of hadron-nuclear interactions with identification of nucleus final state. Spectrometer consists of a wide-aperture magnetic spectrometer with proportional chambers, scintillation counters, hodoscopes and a Ge(Li)-detector base γ-spectrometer. Paper describes an electronic system for acquisition and processing of spectrometric information. MAG spectrometer ensures ∼ 1.2 mm coordinate resolution and 3 mrad angular resolution. Its average efficiency within 0-5 deg angle range is equal to 85%. Energy resolution of γ-spectrometer is equal to 8 and 16 keV at 0.5 and 2.0 MeV photon energy, respectively. Error of 1 GeV energy particle pulse damnation constitutes 2.2%. Resolution of two-particle state efficient mass is equal to 14 MeV/s2
Octupole correlations in positive-parity states of rare-earth and actinide nuclei
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.
In-beam studies of high-spin states of actinide nuclei
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.
In-beam studies of high-spin states of actinide nuclei
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 232U, 233U, 234U, 235U, 238Pu and 239Pu 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, M1/E2 mixing ratios, and g-factors) is presented for 233U. 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...
Ground-state shape phase transitions in nuclei: Thermodynamic analogy and finite-N effects
We study quantum phase transitions between spherical, prolate, and oblate nuclear ground-state shapes using the interacting sd-boson model (sd-IBM) and demonstrate the analogy between the IBM results (also results of any axially symmetric quadrupole collective model) and predictions of the Landau theory of phase transitions in classical thermodynamics. A detailed comparison of the two frameworks is performed exploiting the concept of 'specific heat', introduced in four alternative ways in the quantum case. All these definitions (two of them based on spectroscopic features of the ground state, the others on a randomized version of the model) lead to similar peaked forms of the 'specific heat' at the point of the quantum phase transition. We analyze the effect of an increasing boson number on these curves and observe convergence to the singular phase-transitional behavior in the classical limit. Other observable signatures of the IBM structural phase transitions are also discussed with the aim to facilitate the location of a particular nucleus in the parameter space (extended Casten triangle) near the transitions
Hyperon-nucleon bound states and electroproduction of strangeness on light nuclei.
Dohrmann, F.; Abbott, D.; Ahmidouch, A.; Ambrozewicz, P.; Armstrong, C. S.; Arrington, J.; Bailey, K.; Cummings, W. J.; Gao, H.; Garrow, K.; Geesaman, D. F.; Hafidi, K.; Hansen, J. O.; Jackson, H. E.; Mueller, B.; O' Neill, T. G.; Potterveld, D.; Reimer, P. E.; Reinhold, J.; Zeidman, B.
2002-06-25
The A(e,e{prime}K{sup +})Y X reaction has been investigated in Hall C at Jefferson Lab. Data were taken for Q{sup 2} {approx} 0.35 and 0.5 GeV{sup 2} at a beam energy of 3.245 GeV for {sup 1}H, {sup 2}H, {sup 3}He and {sup 4}He, C and Al targets. The missing mass spectra are fitted with Monte Carlo simulations including {Lambda}, {Sigma}{sup 0}, {Sigma}{sup -} hyperon production. Models for quasifree production are compared to the data, excess yields close to threshold are attributed to FSI. Evidence for {Lambda}-hypernuclear bound states is seen for {sup 3,4}He targets.
Study of the superdeformed states of the gadolinium nuclei: neutron excitations in 147Gd nucleus
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 147Gd nucleus. High spin states in 147Gd have been populating by 122Sn (30Si,5n)147Gd fusion-evaporation reaction with a silicon beam of 158 MeV delivered by the VIVITRON accelerator of the Institut de Recherches Subatomiques. The nucleus γ de-excitations have been measured using the EUROGAM II γ-ray multidetector. On the basis of multiple coincidences, four new superdeformed (SD) rotational bands have been assigned to 147Gd 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 147Gd with 148Gd(2) and 146Gd(1) SD bands has fixed the role of the [651 1/2]α = -1/2 orbital crossing frequency. Theoretical calculations reproduce quite well the 148Gd(2), 127Gd(1,5) and G146Gd(1) dynamical moments of inertia. Using the particle hole excitation nature of 149,148,147,146Gd bands, effective spin alignment of [651 1/2]α= ±1/2, [770 1/2]α = -1/2 and [441 1/2]α = +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]α +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)
The influence of the mechanisms of nuclear reactions on the population of 195mHg and 197mHg(7/2−), 198mTl and 196mTl(7+), and 196mAu and 198mAu(12−) isomeric nuclear states obtained in reactions induced by beams of 3He, 6Li, and 6He weakly bound nuclei is studied. The behavior of excitation functions and high values of isomeric ratios (δm/δg) for products of nuclear reactions proceeding through a compound nucleus and involving neutron evaporation are explained within statistical models. Reactions in which the emission of charged particles occurs have various isomeric ratios depending on the reaction type. The isomeric ratio is lower in direct transfer reactions involving charged-particle emission than in reactions where the evaporation of charged particles occurs. Reactions accompanied by neutron transfer usually have a lower isomeric ratio, which behaves differently for different direct-reaction types (stripping versus pickup reactions)
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...
The nuclei far from the β-stability valley which are referred to as exotic nuclei have attracted considerable interest in recent years. Undoubtedly the study of the exotic nuclei is destined to be one of the frontier fields in nuclear structure physics. The recent experiments with radioactive beams have opened up this new era in nuclear spectroscopy. The lighter exotic nuclei are observed to show quite interesting features. For example, a halo structure has been attributed to 11Li in order to explain the observed large matter radius. Also, it is seen that 31--33Na show deformed characteristics rather than the spherical shape expected from the shell closure at N = 20. This points towards a need for a new investigation of the shell structure as one moves away from the β - stability valley. With the aforementioned interesting features observed for the lighter nuclei, clearly one question of great interest is whether similar effects can be seen in heavy nuclei. New calculations using the relativistic mean field approach have been performed for a range of nuclei over a wide range of isotopes up to those with a large excess of neutrons. In the present talk, some interesting new results obtained from these calculations win be discussed
Measurement of lifetimes of high spin states in the N = 106 nuclei {sup 183}Ir and {sup 182}Os
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.
Full text: It is interesting to obtain values of asymptotical normalization coefficients (ANC) of overlapping functions for a few first levels of bound state of nuclei 14N and 20Ne for calculation of astrophysical S-factors of radiative proton capture 13C(p,γ )14N and 19F(p,γ )20Ne. For this purpose the differential cross sections of the reaction 19F(3He,d20Ne at projectile beam of 3He with energy of 22.3 MeV measured at angels of forward hemisphere and cross sections of reaction 13C(3He,d)14N at region of main stripping peak have been analyzed. The experimental values are taken from our earlier work [1]. At that work the role of coupling channels and contribution of peripheral processes into the amplitude of the reaction were analyzed. In present work in frame of modified DWBA [2, 3] empirical values of ANC of proton binding have been obtained. In frame of EPN [4, 5] method the values of asymptotical coefficients b of bound state function for bindings 14N->13C+p and 20Ne->19F+ p for a few first levels have been calculated. With the values of ANC and b the empirical values of spectroscopic factors have been calculated. The theoretical values of ANC corresponding shell model were calculated with the theoretical values of spectroscopic factors known from literature. Some comparative analysis is made. An opportunity of using the data for estimation of contribution of direct processes into cross section of radiative proton capture is discussed. The work is supported by grant Uzbek Acad. Sci. No 5-04
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
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...
Gysel, M.; Laborde, M.; Bukowiecki, N.; Juranyi, Z.; Hammer, E.; Zieger, P.; Baltensperger, U.; Weingartner, E.
2012-12-01
Black carbon (BC) emitted from combustion sources is the major absorbing component of atmospheric aerosols. The Earth's climate can be influenced by BC particles in several ways, e.g. through absorption of solar radiation or through decreasing the surface albedo of glaciers due to deposited BC particles. Cloud droplets only form on cloud condensation nuclei (CCN). The CCN activation behaviour of BC particles is important for their atmospheric life cycle as wet removal is an important sink. Several laboratory and field studies have shown that BC is less hygroscopic and less CCN active than inorganic or water-soluble organic aerosol components. The goal of this study was to investigate the CCN activation behaviour of BC-containing particles in dependence of their mixing state and compared to non-BC containing particles. In situ measurements of the cloud droplet activation behaviour of aerosol particles were done in winter 2010 at the high-alpine research station Jungfraujoch (3580 m asl), Switzerland. Two different inlets were employed during cloud episodes to selectively collect the interstitial aerosol (all particles that did not form cloud droplets) as well as the total aerosol (interstitial aerosol plus cloud droplet residuals). Both types of aerosol samples were characterized using a Single Particle Soot Photometer (SP2), providing quantitative measurement of BC mass in individual particles as well as information on the mixing state of BC, and further aerosol measurement techniques. Outdoor measurements of microphysical cloud properties were also available. Comparison of the aerosol samples from the interstitial and total inlets makes it possible to determine the properties of the CCN active aerosol as opposed to the interstitial aerosol. The analysis of several cloud events revealed that coated BC particles are more readily activated to CCN compared to uncoated BC particles with equal BC mass. This can actually be expected even for non-hygroscopic coatings due
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
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 ...
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
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...
Mareš, Jiří; Friedman, E.; Gal, A.
-, č. 56 (2006), s. 95-98. ISSN 0323-0465 R&D Projects: GA AV ČR IAA1048305 Institutional research plan: CEZ:AV0Z10480505 Keywords : key words * kaonic nuclei * Kbar-nucleus interactions Subject RIV: BE - Theoretical Physics Impact factor: 0.647, year: 2006
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.
Energy sharing in the decay of the compound nuclei 44Ti and 90Ru excited in high spin states
A detailed study of the decay of 44Ti and 90Ru compound nuclei, via two particle channels involving at least one alpha particle has been performed for the p,α and 2 α channels. This was possible using the combination of the two powerful experimental apparatuses DIAMANT and EUROGAM II. A peculiar behaviour of the energy sharing between the two light particles was found for both systems as a function of the excitation energy in the residual nuclei. Notably, the proton energies are almost independent of the residual nucleus excitation energies Ef while the alpha particle energies decrease when the Ef rises. This experimental results obtained for the first time in exclusive measurements were confirmed also in simulations. It was shown that the implied particles in the compound nucleus decay do not play the same role in the energy sharing. In the case of 90Ru a strong correlation between the residual nucleus excitation energy and its angular momentum was observed
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 ???
Under the assumption that isospin is a good quantum number, symmetry is expected for the transitions from the ground states of T=1, Tz=±1 nuclei to the common excited states of the Tz=0 nucleus situated between the two nuclei. The symmetry can be studied by comparing the strengths of Gamow-Teller (GT) transitions obtained from a (p,n)-type charge-exchange reaction on a target nucleus with Tz=1 with those from the β-decay of the Tz=-1 nucleus. The A=58 system is the heaviest for which such a comparison is possible. As a part of the symmetry study, we measured the GT transitions from 58Ni (Tz=1) to 58Cu (Tz=0) by using the zero-degree (3He,t) reaction at 150 MeV/nucleon. With the achieved resolution of 50 keV, many hitherto unresolved GT states have been identified. The GT transition strengths were obtained for states up to 8 MeV excitation, i.e., near to the Q window limitation (QEC=9.37 MeV) of the β-decay from 58Zn (Tz=- 1) to 58Cu. The strength distribution is compared with that from shell-model calculations. (orig.)
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.
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.
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.)
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
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
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.
O'Dell, Luke A; Ratcliffe, Christopher I
2011-02-10
A combination of density functional and optimal control theory has been used to generate amplitude- and phase-modulated excitation pulses tailored specifically for the (33)S nuclei in taurine, based on one of several reported crystal structures. The pulses resulted in significant signal enhancement (stemming from population transfer from the satellite transitions) without the need for any experimental optimization. This allowed an accurate determination of the (33)S NMR interaction parameters at natural abundance and at a moderate magnetic field strength (11.7 T). The (33)S NMR parameters, along with those measured from (14)N using frequency-swept pulses, were then used to assess the accuracy of various proposed crystal structures. PMID:21174418
Yasuda, N.; Sekiguchi, M. [National Inst. of Radiological Sciences, Chiba (Japan); Nakamura, S.; Kitamura, T. [Yokohama National University, Yokohama, Kanagawa (Japan); Tawara, H. [High Energy Accelerator Research Organization, Tsukuba, Ibaraki (Japan); Doke, T. [National Space Development Agency of Japan (NASDA), Tsukuba, Ibaraki (Japan)
2001-10-01
The HNX (Heavy Nuclear eXplorer) project has been tentatively accepted as one of the NASA's Small Explorer (SMEX) Program. Purpose of this project is the measurement of abundances for heavy nuclei in galactic cosmic rays (GCRs). This information will contribute to get a great knowledge for the origin of GCR. HNX has two large and high sensitive detectors, ENTICE (Energetic Trans-Ion Composition Experiment) and ECCO (Extremely Heavy Cosmic-ray Composition Observer). ECCO experimental module consists the large BP-1 glass detectors (total area; 23 m{sup 2}), will collect the GCRs ({approx}2,000 events for Pt-group and {approx}100 events for actinide) with its high charge resolution (<0.35 e) in space at least 3 years. We report the outline of HNX project and the new techniques for the measurement of large glass detectors. (author)
Collisions between complex atomic nuclei
The use of heavy ion accelerators in the study of nuclear structure and states is reviewed. The reactions discussed are the quasielastic reactions in which small amounts of energy and few particles are exchanged between the colliding nuclei. The development of heavy ion accelerators is also discussed, as well as detection equipment. Exotic phenomena, principally the possible existence of superheavy nuclei, are also treated. (JIW)
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...
Chandran, C Vinod; Hempel, Günter; Bräuniger, Thomas
2011-09-01
In solid-state NMR studies of minerals and ion conductors, quadrupolar nuclei like (7)Li, (23)Na or (133)Cs are frequently situated in close proximity to fluorine, so that application of (19)F decoupling is beneficial for spectral resolution. Here, we compare the decoupling efficiency of various multi-pulse decoupling sequences by acquiring (19)F-decoupled (23)Na-NMR spectra of cryolite (Na(3)AlF(6)). Whereas the MAS spectrum is only marginally affected by application of (19)F decoupling, the 3Q-filtered (23)Na signal is very sensitive to it, as the de-phasing caused by the dipolar interaction between sodium and fluorine is three-fold magnified. Experimentally, we find that at moderate MAS speeds, the decoupling efficiencies of the frequency-swept decoupling schemes SW(f)-TPPM and SW(f)-SPINAL are significantly better than the conventional TPPM and SPINAL sequences. The frequency-swept sequences are therefore the methods of choice for efficient decoupling of quadrupolar nuclei with half-integer spin from fluorine. PMID:21856132
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
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
We have investigated systematically kaonic nuclei which are ppnK-, pppK-, pppnK-, 6BeK-, 9BK- and 11CK-. Since I = 0 K-barN interaction, which is very attractive, plays an essential role in kaonic nuclei, we should treat it adequately. For this purpose, we have improved the framework of antisymmetrized molecular dynamics (AMD): 1) we can treat pK-/nK-bar0 mixing and 2) perform not only angular-momentum projection but also isospin projection. As a result of our calculation with a new framework of AMD, all kaonic nuclei we calculated are deeply bound by about 100 MeV as a discrete state. They have various structures with highly dense state. We have also investigated double kaonic nuclei, ppnK-K- and ppnK-K-. They are more shrunk than single kaonic nuclei, but the binding energy per single kaon (E(K-bar)) is about 100 MeV, which is equal to that in the case of single kaonic nuclei. (author)
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
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.)
Review on theoretical researches of superheavy nuclei
We review the recent progress of theoretical researches on heavy nuclei and superheavy nuclei. At first we analyze the experimental data of long lifetime heavy nuclei and discuss their stability. Then the calculated binding energies and alpha-decay energies of heavy and superheavy nuclei from different models are compared and discussed. This includes the results from the local binding energy formula of heavy nuclei with Z ≥ 90 and N ≥ 130, those from the relativistic mean-field model, and from other models. For the local binding energy formula, it can reproduce experimental binding energies of known heavy and superheavy nuclei well. The relativistic mean-field model and non-relativistic mean-field model show that there is shape coexistence in superheavy nuclei. For some superheavy nuclei, superdeformed prolate shape can be their ground states and there are isomers in lowly excited states due to shape coexistence. The properties of some unknown superheavy nuclei are predicted. Some new views on the stability and on half-lives of heavy and superheavy nuclei are presented. Possible new phenomenon in superheavy region is analyzed and discussed. (author)
Wu, Xian-Ye
2015-01-01
We present a comprehensive study of low-lying states in even-even Ne, Mg, Si, S, Ar isotopes with the multireference density functional theory (MR-DFT) based on a relativistic point-coupling energy density functional (EDF). Beyond mean-field (BMF) effects are taken into account by configuration mixing of both particle-number and angular-momentum projected axially deformed states with generator coordinate method (GCM). Global performance of the MR-DFT for the properties of both ground state and of the first $2^+, 4^+$ states is examined, in comparison with previous studies based on nonrelativistic EDFs and available data. Our results indicate that an EDF parameterized at the BMF level is demanded to achieve a quantitative description.
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.
PPCO: polarizational-polarizational correlation from oriented nuclei
A Polarizational-Polarizational Correlation from Oriented Nuclei (PPCO) measuring method is described. The method allows one to determine spin and parity of the excited states of nuclei as well as multipole gamma transitions
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.
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
Coupled-Cluster Theory for Nuclei
The quantum-many body problem spans numerous scientific disciplines ranging from condensed matter to quantum dots, to high-temperature superconductors, and to nuclei. In these proceedings, we discuss the development of coupled-cluster techniques and their application to nuclei. We concentrate specifically on calculations pertaining to the ground- and excited-state properties of 4He and 16O
The deexcitation of the 8.6 μs isomer of 3999Y has been studied using γ-ray spectroscopy techniques at LOHENGRIN and JOSEF. The resultant level scheme is analyzed within the framework of the particle-rotor coupling model. The ground-state band, to spin 19/2+, is found to have band properties consistent with a π[422 5/2] Nilsson assignment. The 8.6 μs isomer and a side band with a band-head half-life of 1.4 ns are found to have Jsup(π) values of 17+/2 and 11+/2, respectively. Their properties are consistent with a [π[422 5/2]ν[411 3/2]ν[404 9/2
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.
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 $\\alp...
Neutron scattering on deformed nuclei
Measurements of neutron elastic and inelastic differential cross sections around 14 MeV for 9Be, C, 181Ta, 232Th, 238U and 239Pu have been analyzed using a coupled channel (CC) formalism for deformed nuclei and phenomenological global optical model potentials (OMP). For the actinide targets these results are compared with the predictions of a semi-microscopic calculation using Jeukenne, Lejeune and Mahaux (JLM) microscopic OMP and a deformed ground state nuclear density. The overall agreement between calculations and the measurements is reasonable good even for the very light nuclei, where the quality of the fits is better than those obtained with spherical OMP
Yarmukhamedov, R
2016-01-01
Asymptotic expressions for the radial and full wave functions of a three{body bound halo nuclear system with two charged particles in relative coordinates are obtained in explicit form, when the relative distance between two particles tends to infinity. The obtained asymptotic forms are applied to the analysis of the asymptotic behavior of the three-body (pn?) wave functions for the halo ($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, $^...
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)
This paper covers the following aspects of isobar excitations in nuclei: Nuclear spin response; Electromagnetic probes; Pion-nuclear reactions; Baryon charge exchange reactions; Charge exchange reactions on nuclei; and Exclusive spectra
Decay of heavy and superheavy nuclei
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.
Collective excitations in nuclei
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.