Alpha particle cluster states in (fp)-shell nuclei
International Nuclear Information System (INIS)
Merchant, A.C.
1987-07-01
Alpha particle cluster structure is known experimentally to persist throughout the mass range 16 ≤ A ≤ 20, and has been very successfully described in this region in terms of the Buck-Dover-Vary local potential cluster model. It is argued that an analogous cluster structure should be present in nuclei at the beginning of the (fp) - shell, and the available experimental data are examined to determine likely alpha particle cluster state candidates in the mass range 40 ≤ A ≤ 44. Calculations of the cluster state spectra and mean square cluster-core separation distances (which may be readily used to evaluate E2 electromagnetic transition rates) for sup(40)Ca, sup(42)Ca, sup(42)Sc, sup(43)Sc, sup(43)Ti and sup(44)Ti using the above mentioned model are presented, and compared with experimental measurements where possible. The agreement between theory and experiment is generally good (although inferior to that obtained in the (sd)-shell) and points to the desirability of an extension and improvement of the measurements of the properties of the excited states in these nuclei. (author)
Isospin invariant boson models for fp-shell nuclei
International Nuclear Information System (INIS)
Van Isacker, P.
1994-01-01
Isospin invariant boson models, IBM-3 and IBM-4, applicable in nuclei with neutrons and protons in the same valence shell, are reviewed. Some basic results related to these models are discussed: the mapping onto the shell model, the relation to Wigner's supermultiplet scheme, the boson-number and isospin dependence of parameters, etc. These results are examined for simple single-j shell situations (e.g. f 7/2 ) and their extension to the f p shell is investigated. Other extensions discussed here concern the treatment of odd-mass nuclei and the classification of particle-hole excitations in light nuclei. The possibility of a pseudo-SU(4) supermultiplet scheme in f p -shell nuclei is discussed. (author) 4 figs., 3 tabs., 23 refs
Two-proton radioactivity in proton-rich fp shell nuclei at high spin
Energy Technology Data Exchange (ETDEWEB)
Aggarwal, Mamta [Nuclear Science Centre, Aruna Asaf Ali Marg, Post Box 10502, New Delhi 110067 (India)
2006-07-15
Two-proton radioactivity in extremely proton-rich fp shell nuclei at high spins is investigated in a theoretical framework. Separation energy and entropy fluctuate with spin and hence affect the location of the proton drip line.
Two-proton radioactivity in proton-rich fp shell nuclei at high spin
International Nuclear Information System (INIS)
Aggarwal, Mamta
2006-01-01
Two-proton radioactivity in extremely proton-rich fp shell nuclei at high spins is investigated in a theoretical framework. Separation energy and entropy fluctuate with spin and hence affect the location of the proton drip line
The collective bands of positive parity states in odd-A (fp) shell nuclei
International Nuclear Information System (INIS)
Ahalpara, D.P.
1979-01-01
The low-lying collective bands of positive parity states in (fp) shell nuclei are described in the deformed Hartree-Fock method by projecting states of definite angular momenta from 'the lowest energy intrinsic states in (sd)sup(-1)(fp)sup(n+1) configurations. The modified Kuo-Brown effective interaction for (fp) shell and modified surface delta interaction (MSDI) for a hole in (sd) shell with a particle in (fp) shell have been used. The collective bands of states are in general well reproduced by the effective interactions. The excitation energies of the band head states are however off by about one MeV. The calculated magnetic moments of the band head j = 3/2 + states are in reasonable agreement with experiment. Using effective charges esub(p) = 1.33 e and esub(n) = 0.64 e fairly good agreement is obtained for E(2) transitions. The hindered M(1) transition strengths are reproduced to the correct order, however they are slightly higher compared to the experiment. (author)
One particle-hole excitations in p- and fp-shell nuclei
International Nuclear Information System (INIS)
Hees, A.G.M. van.
1982-01-01
Results are presented of shell model calculations of medium and light atomic nuclei. The influence of the allowance of one particle-hole excitations is investigated. This enables improved descriptions of intermediate mass nuclei in the fp-shell. For light p-shell nuclei one particle-hole excitations create exclusively situations with abnormal parity. The description of situations with normal parity is not changed by enlarging the model space. In the first chapter shell-model calculations are performed on the light Ni-isotopes (A = 57-59). One nucleon is allowed to be excited from the fsub(7/2) orbit to one of the other fp-shell orbits. The general observation in the enlarged model space is that one can use operators that require a much weaker 'renormalization' and the calculation requires only a selected set of matrix elements of the Hamiltonian. An additional advantage of the inclusion of one particle-hole excitations is that it allows a description of several intruder states, i.e. states that cannot be produced with the assumption of a closed 56 Ni core. In the second chapter the nuclei with mass number A = 52-55, i.e. a small number of holes in the 56 Ni core, are investigated similarly. In the third chapter much lighter nuclei (A = 4-16) are discussed. For a theoretical description of nonnormal-parity states one has to admit the excitation of at least one nucleon to a higher harmonic-oscillator major-shell. (Auth.)
Band crossing and signature splitting in odd mass fp shell nuclei
International Nuclear Information System (INIS)
Velazquez, Victor; Hirsch, Jorge G.; Sun, Yang
2001-01-01
Structure of two sets of mirror nuclei: 47 V- 47 Cr and 49 Cr- 49 Mn, as well as 49 V and 51 Mn, is studied using the projected shell model. Their yrast spectra are described as an interplay between the angular momentum projected states around the Fermi level which carry different intrinsic K-quantum numbers. The deviations from a regular rotational sequence are attributed to band crossing and signature splitting, which are usually discussed in heavy nuclear systems. Our results agree reasonably with experimental data, and are comparable with those from the full pf shell model calculations
Core polarization and 3/2 states of some f-p shell nuclei
International Nuclear Information System (INIS)
Shelly, S.
1976-01-01
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 50 Ti, 52 Cr, 54 Fe and 56 Fe. 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)
Theoretical spectroscopy and the fp shell
International Nuclear Information System (INIS)
Poves, A.; Zuker, A.
1980-01-01
The recently developed quasiconfiguration method is applied to fp shell nuclei. Second order degenerate perturbation theory is shown to be sufficient to produce, for low lying states, the same results as large diagonalizations in the f(7/2)p(3/2)p(1/2)f(5/2)sup(n) full space. due to the operation of linked cluster mechanisms. Realistic interactions with minimal monopole changes are shown to be successful in reproducing spectra, binding energies, quadrupole moments and transition rates. Large shell model spaces are seen to exhibit typical many body behaviour. Quasiconfigurations allow insight into the underlying coupling schemes
International Nuclear Information System (INIS)
Wienands, U.
1983-05-01
The (α, 2 He)-reaction was studied at 56-57 MeV incident energy at the target nuclei sup(58,60,62,64)Ni. In a laboratory angular range from 15 0 -37.5 0 the angular distributions of the absolute differential cross section were taken up. The measurements were performed with the position resolving 2 He detector developed in Bonn. By means of DWBA calculations for the first time in all final nuclei states with the configurations (fsub(5/2), gsub(9/2)) 7 -(gsub(9/2)) 8 2 +, and (gsub(9/2), dsub(5/2)) 6 + could be identified; these were except the Jsup(π)=7 - states in 60 Ni hitherto not known. The two-neutron binding energies of these states were under inclusion of further states known from literature compared with shell model calculations according to the weak coupling method of Bansal and French. By a set of 4 parameters both the two-neutron binding energies of the (fsub(5/2), gsub(9/2)) 7 - and (gsub(9/2)) 2 sub(8+) states and the one-particle binding energies of the f - sub(5/2) and g + sub(5/2) one-neutron states over a large number of nuclei could very well be reproduced. For calculations on the states with the configuration (gsub(9/2), dsub(5/2)) 6 + the present data set is not yet sufficient. The found agreement of the calculations with the experimental data shows that two-neutron high spin states in the fp shell nuclei can be correctly described by this simple picture. (orig.) [de
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
(6Li,d) reaction on sd-, fp- and g-shell nuclei in ZR- and FR-DWBA formalisms
International Nuclear Information System (INIS)
Rahman, M.A.; Mecking, M.; Strohbusch, U.
1991-06-01
( 6 Li,d) reaction angular distributions on target nuclei 16 ≤ A ≤ 90 have been analyzed using both ZR- and FR-DWBA formalisms. The most prevalent method of analysis of alpha-transfer reactions such as( 6 Li,d) and its reverse (d, 6 Li) (where the wave function at zero distance in the p-state of relative cluster motion in the A = 6 nuclei will not have node) is the ZR-DWBA calculations due to the relatively short time of computation. It is of particular interest to verify whether FR-DWBA calculations result in similar S α - values to those of ZR-DWBA or not. It is found that to derive similar S α -values as in FR-DWBA calculations, one requires relatively large real well depth in ZR-DWBA calculations. Qualitative discussions have been made in this direction. (author). 12 refs, 3 figs, 2 tabs
Energy Technology Data Exchange (ETDEWEB)
Rubio, B., E-mail: Berta.Rubio@ific.uv.es [IFIC, CSIC-Universidad de Valencia, E-46071 Valencia (Spain); Orrigo, S.E.A. [IFIC, CSIC-Universidad de Valencia, E-46071 Valencia (Spain); Kucuk, L. [Department of Physics, Istanbul University, Istanbul (Turkey); Montaner-Pizá, A. [IFIC, CSIC-Universidad de Valencia, E-46071 Valencia (Spain); Fujita, Y. [Department of Physics, Osaka University, Toyonaka, Osaka 560-0043 (Japan); RCNP, Osaka University, Ibaraki, Osaka 567-0047 (Japan); Fujita, H. [RCNP, Osaka University, Ibaraki, Osaka 567-0047 (Japan); Blank, B. [CENBG, Université Bordeaux 1, UMR 5797 CNRS/IN2P3, BP 120, F-33175 Gradignan (France); Gelletly, W. [Department of Physics, University of Surrey, Guildford GU2 7XH, Surrey (United Kingdom); Adachi, T. [RCNP, Osaka University, Ibaraki, Osaka 567-0047 (Japan); Agramunt, J.; Algora, A. [IFIC, CSIC-Universidad de Valencia, E-46071 Valencia (Spain); Ascher, P. [CENBG, Université Bordeaux 1, UMR 5797 CNRS/IN2P3, BP 120, F-33175 Gradignan (France); Bilgier, B. [Department of Physics, Istanbul University, Istanbul (Turkey); Cáceres, L. [GANIL, CEA/DSM-CNRS/IN2P3, BP 55027, F-14076 Caen (France); Cakirli, R.B. [Department of Physics, Istanbul University, Istanbul (Turkey); France, G. de [GANIL, CEA/DSM-CNRS/IN2P3, BP 55027, F-14076 Caen (France); Ganioğlu, E. [Department of Physics, Istanbul University, Istanbul (Turkey); Gerbaux, M.; Giovinazzo, J.; Grevy, S. [CENBG, Université Bordeaux 1, UMR 5797 CNRS/IN2P3, BP 120, F-33175 Gradignan (France); and others
2014-06-15
This paper concerns the experimental study of the β decay properties of few proton-rich fp-shell nuclei. The nuclei were produced at GANIL in fragmentation reactions, separated with the LISE spectrometer and stopped in an implantation detector surrounded by Ge detectors. The β-delayed gammas, β-delayed protons and the exotic β-delayed gamma-proton emission have been studied. Preliminary results are presented. The decay of the T{sub z}=−2 nucleus {sup 56}Zn has been studied in detail. Information from the β-delayed protons and β-delayed gammas has been used to deduce the decay scheme. The exotic beta-delayed gamma-proton decay has been observed for the first time in the fp-shell. The interpretation of the data was made possible thanks to the detailed knowledge of the mirror Charge Exchange (CE) process and the gamma de-excitation of the states in {sup 56}Co, the mirror nucleus of {sup 56}Cu.
fp shell spectroscopy: numerical calculations and theoretical aspects
International Nuclear Information System (INIS)
Pasquini, E.A.
1976-01-01
The fp shell spectroscopy is reviewed and the fsup(n) model is introduced. It is shown that the two-body Hamiltonian monopolar terms play a very important part in the behavior of these spectra, and that realistic interactions do not reproduce them. The detailed study of the following nuclei was undertaken: 47 Ca, 48 Ca, 49 Ca, 56 Ni, 48 Sc, 50 Sc, 50 Ti, 46 Ti, 50 Cr, 47 V and 49 Cr. It is shown that very precise values of the few parameters defining the monopolar contributions could be extracted from the comparison between calculations and experimental data. The study of the binding energies of all the nuclei from 40 Ca to 56 Ni shows that it is necessary to introduce three-body forces. The results also reveal the effect of nondiagonal multipoles which are well reproduced by realistic interactions. A better understanding of the electromagnetic behavior of the fsup(n) nuclei of their conjugaison properties and of the relation between 42 Sc and 48 Sc was obtained. Several calculations of two-body transfer amplitudes were proposed [fr
Hot rotating fp shell Fe isotopes near proton drip line
International Nuclear Information System (INIS)
Aggarwal, Mamta
2003-01-01
F p shell 44-58 Fe nuclei have been investigated in highly excited state using the statistical theory of hot rotating nucleus. Effects of thermal and rotational excitation at drip line nuclei are studied
Transitional nuclei near shell closures
Energy Technology Data Exchange (ETDEWEB)
Mukherjee, G. [Variable Energy Cyclotron Centre, 1/AF Bidhan Nagar, Kolkata 700064 (India); Pai, H. [Variable Energy Cyclotron Centre, 1/AF Bidhan Nagar, Kolkata 700064, India and Present Address: Institut für Kernphysik, Technische Universität Darmstadt, Schlossgartenstrasse 9, 64289 Darmstadt (Germany)
2014-08-14
High spin states in Bismuth and Thallium nuclei near the Z = 82 shell closure and Cesium nuclei near the N = 82 shell closure in A = 190 and A = 130 regions, respectively, have been experimentally investigated using heavy-ion fusion evaporation reaction and by detecting the gamma rays using the Indian National Gamma Array (INGA). Interesting shape properties in these transitional nuclei have been observed. The results were compared with the neighboring nuclei in these two regions. The total Routhian surface (TRS) calculations have been performed for a better understanding of the observed properties. In mass region A = 190, a change in shape from spherical to deformed has been observd around neutron number N = 112 for the Bi (Z = 83) isotopes with proton number above the magic gap Z = 82, whereas, the shape of Tl (Z = 81) isotopes with proton number below the magic gap Z = 82 remains stable as a function of neutron number. An important transition from aplanar to planar configuration of angular momentum vectors leading to the occurance of nuclar chirality and magnetic rotation, respectively, has been proposed for the unique parity πh{sub 11/2}⊗νh{sub 11/2} configuration in Cs isotopes in the mass region A ∼ 130 around neutron number N = 79. These results are in commensurate with the TRS calculations.
Shell gap reduction in neutron-rich N=17 nuclei
International Nuclear Information System (INIS)
Obertelli, A.; Gillibert, A.; Alamanos, N.; Alvarez, M.; Auger, F.; Dayras, R.; Drouart, A.; France, G. de; Jurado, B.; Keeley, N.; Lapoux, V.; Mittig, W.; Mougeot, X.; Nalpas, L.; Pakou, A.; Patronis, N.; Pollacco, E.C.; Rejmund, F.; Rejmund, M.; Roussel-Chomaz, P.; Savajols, H.; Skaza, F.; Theisen, Ch.
2006-01-01
The spectroscopy of 27 Ne has been investigated through the one-neutron transfer reaction 26 Ne(d,p) 27 Ne in inverse kinematics at 9.7 MeV/nucleon. The results strongly support the existence of a low-lying negative parity state in 27 Ne, which is a signature of a reduced sd-fp shell gap in the N=16 neutron-rich region, at variance with stable nuclei
Understanding Nuclei in the upper sd - shell
Sarkar, M. Saha; Bisoi, Abhijit; Ray, Sudatta; Kshetri, Ritesh; Sarkar, S.
2013-01-01
Nuclei in the upper-$sd$ shell usually exhibit characteristics of spherical single particle excitations. In the recent years, employment of sophisticated techniques of gamma spectroscopy has led to observation of high spin states of several nuclei near A$\\simeq$ 40. In a few of them multiparticle, multihole rotational states coexist with states of single particle nature. We have studied a few nuclei in this mass region experimentally, using various campaigns of the Indian National Gamma Array...
Neutron transfer reactions in the fp-shell region
International Nuclear Information System (INIS)
Mahgoub, Mahmoud
2008-01-01
Neutron transfer reactions were used to study the stability of the magic number N=28 near 56 Ni. On one hand the one-neutron pickup (d,p) reaction was used for precision spectroscopy of single-particle levels in 55 Fe. On the other hand we investigated the two-neutron transfer mechanism into 56 Ni using the pickup reaction 58 Ni(vectorp,t) 56 Ni. In addition the reliability of inverse kinematics reactions at low energy to study exotic nuclei was tested by the neutron transfer reactions t( 40 Ar,p) 42 Ar and d( 54 Fe,p) 55 Fe using tritium and deuterium targets, respectively, and by comparing the results with those of the normal kinematics reactions. The experimental data, differential cross-section and analyzing powers, are compared to DWBA and coupled channel calculations utilizing the code CHUCK3. By performing the single-neutron stripping reaction (vectord,p) on 54 Fe the 1f 7/2 shell in the ground state configuration was found to be partly broken. The instability of the 1f 7/2 shell and the magic number N=28 was confirmed once by observing a number of levels with J π = 7/2 - at low excitation energies, which should not be populated if 54 Fe has a closed 1f 7/2 shell, and also by comparing our high precision experimental data with a large scale shell model calculation using the ANTOINE code [5]. Calculations including a partly broken 1f 7/2 shell show better agreement with the experiment. The instability of the 1f 7/2 shell was confirmed also by performing the two-neutron pick-up reaction (vectorp,t) on 58 Ni to study 56 Ni, where a considerable improvement in the DWBA calculation was observed after considering 1f 7/2 as a broken shell. To prove the reliability of inverse kinematics transfer reactions at low energies (∝ 2 AMeV), the aforementioned single-neutron transfer reaction (d,p) was repeated using a beam of 54 Fe ions and a deuteron target. From this inverse kinematics experiment we were able to reproduce the absolute cross-section and angular
Neutron transfer reactions in the fp-shell region
Energy Technology Data Exchange (ETDEWEB)
Mahgoub, Mahmoud
2008-06-26
Neutron transfer reactions were used to study the stability of the magic number N=28 near {sup 56}Ni. On one hand the one-neutron pickup (d,p) reaction was used for precision spectroscopy of single-particle levels in {sup 55}Fe. On the other hand we investigated the two-neutron transfer mechanism into {sup 56}Ni using the pickup reaction {sup 58}Ni((vector)p,t){sup 56}Ni. In addition the reliability of inverse kinematics reactions at low energy to study exotic nuclei was tested by the neutron transfer reactions t({sup 40}Ar,p){sup 42}Ar and d({sup 54}Fe,p){sup 55}Fe using tritium and deuterium targets, respectively, and by comparing the results with those of the normal kinematics reactions. The experimental data, differential cross-section and analyzing powers, are compared to DWBA and coupled channel calculations utilizing the code CHUCK3. By performing the single-neutron stripping reaction ((vector)d,p) on {sup 54}Fe the 1f{sub 7/2} shell in the ground state configuration was found to be partly broken. The instability of the 1f{sub 7/2} shell and the magic number N=28 was confirmed once by observing a number of levels with J{sup {pi}} = 7/2{sup -} at low excitation energies, which should not be populated if {sup 54}Fe has a closed 1f{sub 7/2} shell, and also by comparing our high precision experimental data with a large scale shell model calculation using the ANTOINE code [5]. Calculations including a partly broken 1f{sub 7/2} shell show better agreement with the experiment. The instability of the 1f{sub 7/2} shell was confirmed also by performing the two-neutron pick-up reaction ((vector)p,t) on {sup 58}Ni to study {sup 56}Ni, where a considerable improvement in the DWBA calculation was observed after considering 1f{sub 7/2} as a broken shell. To prove the reliability of inverse kinematics transfer reactions at low energies ({proportional_to} 2 AMeV), the aforementioned single-neutron transfer reaction (d,p) was repeated using a beam of {sup 54}Fe ions and a
Understanding nuclei in the upper sd - shell
Energy Technology Data Exchange (ETDEWEB)
Sarkar, M. Saha; Bisoi, Abhijit; Ray, Sudatta [Nuclear Physics Division, Saha Institute of Nuclear Physics, Kolkata 700064 (India); Kshetri, Ritesh [Nuclear Physics Division, Saha Institute of Nuclear Physics, Kolkata 700064, India and Sidho-Kanho-Birsha University, Purulia - 723101 (India); Sarkar, S. [Indian Institute of Engineering Science and Technology, Shibpur, Howrah - 711103 (India)
2014-08-14
Nuclei in the upper-sd shell usually exhibit characteristics of spherical single particle excitations. In the recent years, employment of sophisticated techniques of gamma spectroscopy has led to observation of high spin states of several nuclei near A ≃ 40. In a few of them multiparticle, multihole rotational states coexist with states of single particle nature. We have studied a few nuclei in this mass region experimentally, using various campaigns of the Indian National Gamma Array setup. We have compared and combined our empirical observations with the large-scale shell model results to interpret the structure of these nuclei. Indication of population of states of large deformation has been found in our data. This gives us an opportunity to investigate the interplay of single particle and collective degrees of freedom in this mass region.
Shell model calculations for exotic nuclei
International Nuclear Information System (INIS)
Brown, B.A.; Wildenthal, B.H.
1991-01-01
A review of the shell-model approach to understanding the properties of light exotic nuclei is given. Binding energies including p and p-sd model spaces and sd and sd-pf model spaces; cross-shell excitations around 32 Mg, including weak-coupling aspects and mechanisms for lowering the ntw excitations; beta decay properties of neutron-rich sd model, of p-sd and sd-pf model spaces, of proton-rich sd model space; coulomb break-up cross sections are discussed. (G.P.) 76 refs.; 12 figs
Shell model for warm rotating nuclei
Energy Technology Data Exchange (ETDEWEB)
Matsuo, M.; Yoshida, K. [Kyoto Univ. (Japan); Dossing, T. [Univ. of Copenhagen (Denmark)] [and others
1996-12-31
Utilizing a shell model which combines the cranked Nilsson mean-field and the residual surface and volume delta two-body forces, the authors discuss the onset of rotational damping in normal- and super-deformed nuclei. Calculation for a typical normal deformed nucleus {sup 168}Yb indicates that the rotational damping sets in at around 0.8 MeV above the yrast line, and about 30 rotational bands of various length exists at a given rotational frequency, in overall agreement with experimental findings. It is predicted that the onset of rotational damping changes significantly in different superdeformed nuclei due to the variety of the shell gaps and single-particle orbits associated with the superdeformed mean-field.
High spin states in the f-p shell
International Nuclear Information System (INIS)
Delaunay, J.
1975-01-01
The high spin states (HSS) in Fe, Co, Ni (Z=26,27,28) isotopes exhibit features characteristics of soft or transition nuclei, 56 Fe being as well deformed prolate nucleus and the Ni isotopes often throught of as spherical. The methodology used to identify these HSS is the so called DCO (directional correlation of oriented nuclei) or ratio method which, by combining the angular distribution data plus one point of a triple γ-γ correlation in an asymmetric geometry, gives result that is found equivalent to a complete angular correlation to assign spin and mixing ratios. Some results collected with this methodology are presented [fr
The Structure of the Heavy Calcium Isotopes and the Effective Interaction in the sd-fp Shell
Dorvaux, O; Nowacki, F; Courtin, S; Marechal, F; Siiskonen, T M; Perrot, F; Pietri, S B
2002-01-01
Nuclei with 40 $<$ A $<$ 56, near the stability line, are very well described in the frame of the shell model. However, when the number of neutrons increases, the situation becomes more complex which explains why the interaction can be found very dissimilar within different calculations. Heavy Ca isotopes, because of the simplicity of their wave-functions, correspond to the optimal choice to fix unambiguously the interaction in this mass region.\\\\ It is proposed to measure the $\\beta$-decay of $^{51, 52, 53}$K with the help of an utmost performing neutron (TONNERRE array) and $\\gamma$- (Miniball clusters) detection, allowing efficient coincidence measurements. This will allow the lowest lying Gamow-Teller states to be located in $^{51, 52, 53}$Ca, and the still unknown properties of natural parity states to be investigated. The awaited results should allow to settle the n-n interaction in the fp shell and the Gnp matrix accross the sd and fp shells, one step farther from stability, by comparison with fu...
High spin structure of {sup 35}Cl and the sd-fp shell gap
Energy Technology Data Exchange (ETDEWEB)
Kshetri, Ritesh [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India); Saha Sarkar, M. [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India)]. E-mail: maitrayee.sahasarkar@saha.ac.in; Ray, Indrani [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India); Banerjee, P. [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India); Sarkar, S. [Department of Physics, Bengal Engineering and Science University, Shibpur, Howrah 711103 (India); Raut, Rajarshi [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India); Goswami, A. [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India); Chatterjee, J.M. [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India); Chattopadhyay, S. [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India); Datta Pramanik, U. [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India); Mukherjee, A. [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India); Dey, C.C. [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India); Bhattacharya, S. [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India); Dasmahapatra, B. [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India); Bhowal, Samit [Department of Physics, Surendranath Evening College, Kolkata 700009 (India); Gangopadhyay, G. [University of Calcutta, 92, Acharya Prafulla Chandra Road, Kolkata 700009 (India); Datta, P. [Anandamohan College, 102/1, Raja Rammohan Sarani, Kolkata 700009 (India); Jain, H.C. [Tata Institute of Fundamental Research, Mumbai 400005 (India); Bhowmik, R.K. [Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India); Muralithar, S.; Singh, R.P.; Kumar, R. [Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India)
2007-01-15
The high spin states of {sup 35}Cl have been studied by in-beam {gamma}-spectroscopy following the fusion-evaporation reaction {sup 12}C({sup 28}Si,{alpha}p){sup 35}Cl at E{sub lab}=70 and 88 MeV, using the Indian National Gamma (Clover) Array (INGA). Lifetimes of six new excited states have been estimated for the first time. To understand the underlying structure of the levels and transition mechanisms, experimental results have been compared with those from the large basis cross-shell shell model calculations. Involvement of orbitals from fp shell and squeezing of the sd-fp shell gap seem to be essential for reliable reproduction of high spin states.
High spin structure of 35Cl and the sd-fp shell gap
International Nuclear Information System (INIS)
Kshetri, Ritesh; Saha Sarkar, M.; Ray, Indrani; Banerjee, P.; Sarkar, S.; Raut, Rajarshi; Goswami, A.; Chatterjee, J.M.; Chattopadhyay, S.; Datta Pramanik, U.; Mukherjee, A.; Dey, C.C.; Bhattacharya, S.; Dasmahapatra, B.; Bhowal, Samit; Gangopadhyay, G.; Datta, P.; Jain, H.C.; Bhowmik, R.K.; Muralithar, S.; Singh, R.P.; Kumar, R.
2007-01-01
The high spin states of 35 Cl have been studied by in-beam γ-spectroscopy following the fusion-evaporation reaction 12 C( 28 Si,αp) 35 Cl at E lab =70 and 88 MeV, using the Indian National Gamma (Clover) Array (INGA). Lifetimes of six new excited states have been estimated for the first time. To understand the underlying structure of the levels and transition mechanisms, experimental results have been compared with those from the large basis cross-shell shell model calculations. Involvement of orbitals from fp shell and squeezing of the sd-fp shell gap seem to be essential for reliable reproduction of high spin states
Spectral distribution study of nuclei in 2p-1f shell
International Nuclear Information System (INIS)
Haq, R.; Parikh, J.C.
1975-01-01
Systematics of nuclei in the beginning of fp-shell are investigated using the spectral distribution method of French. The centroid energies and widths for various distributions are evaluated using the interaction of Kuo with the modification suggested by McGrory et al. The two moment distributions are used to determine ground state energies, fractional occupancy of the single particle orbits for ground states and low lying spectra of various nuclei in this shell. The results are compared with the deformed configuration mixing calculations of Dhar et al. The goodness of Wigner SU(4) symmetry in these nuclei has been investigated. The mixing of various SU(4) representations near the ground state provides a measure of symmetry mixing and the substantial admixture in most of the cases shows that it is badly broken, largely due to the single particle spin orbit coupling. (author)
Inner shell ionization by incident nuclei
International Nuclear Information System (INIS)
Hansteen, J.M.
1974-10-01
The atomic Coulomb excitation process induced by impinging heavy charged particles such as protons, deuterons, α-particles and complex heavy ions is reviewed. Recent experimental and theoretical efforts have led toimproved understanding of the atomic Coulomb excitation as well as to discovery of new types of ionization mechanisms. The following models are mentioned: the Plane Wave Born Approximation (PWBA); theeeeeeeeeeeee modified PWBA model; the Binary Encounter Approximation (BEA); the Semi-Classical Approximation (SCA); the Perturbed-Stationary-State model (PSS). The structure of the SCA model is more thoroughly treated. Experimental results on single Coulomb ionizations of the K-, L-, and M-shells, and of the connected sub-shells by protons are compared with predictions. Most calculations are based on straight line projectile paths and non-relativistic hydrogen-like target electron wave functions. The BEA model and the SCA model seem to work reasonably well for multiple Coulomb ionizations by stripped light ions. Background effects in ion-atom collisions are commented upon. Future aspects of atomic Coulomb excitation by incident nuclei and ions are discussed. The interplay between Coulomb induced processes and united atom phenomena is especially mentioned. The simple ionization models have yielded valuable insights but it is suggested that this branch of collision physics has reached a turning point where new and more advanced and unifying models are needed. (JIW)
Isospin symmetry breaking in sd shell nuclei
International Nuclear Information System (INIS)
Lam, Y.W.
2011-12-01
In the thesis, we develop a microscopic approach to describe the isospin-symmetry breaking effects in sd-shell nuclei. The work is performed within the nuclear shell model. A realistic isospin-conserving Hamiltonian is perfected by a charge-dependent part consisting of the Coulomb interaction and Yukawa-type meson exchange potentials to model charge-dependent forces of nuclear origin. The extended database of the experimental isobaric mass multiplet equation coefficients was compiled during the thesis work and has been used in a fit of the Hamiltonian parameters. The constructed Hamiltonian provides an accurate theoretical description of the isospin mixing nuclear states. A specific behaviour of the IMME (Isobaric Multiplet Mass Equation) coefficients have been revealed. We present two important applications: (i) calculations of isospin-forbidden proton emission amplitudes, which is often of interest for nuclear astrophysics, and (ii) calculation on corrections to nuclear Fermi beta decay, which is crucial for the tests of fundamental symmetries of the weak interaction. (author)
Stability of bubble nuclei through Shell-Effects
Dietrich, Klaus; Pomorski, Krzysztof
1997-01-01
We investigate the shell structure of bubble nuclei in simple phenomenological shell models and study their binding energy as a function of the radii and of the number of neutron and protons using Strutinsky's method. Shell effects come about, on the one hand, by the high degeneracy of levels with large angular momentum and, on the other, by the big energy gaps between states with a different number of radial nodes. Shell energies down to -40 MeV are shown to occur for certain magic nuclei. E...
Shell structure in superdeformed nuclei at high rotational frequencies
International Nuclear Information System (INIS)
Ploszajczak, M.
1980-01-01
Properties of the shell structure in superdeformed nuclei at high rotational frequencies are discussed. Moreover, stability of the high spin compound nucleus with respect to the fission and the emission of light particles is investigated. (author)
Shell stabilization of super- and hyperheavy nuclei without magic gaps
International Nuclear Information System (INIS)
Bender, M.; Nazarewicz, W.; Oak Ridge National Lab., TN; Warsaw Univ.; Reinhard, P.G.; Oak Ridge National Lab., TN
2001-05-01
Quantum stabilization of superheavy elements is quantified in terms of the shell-correction energy. We compute the shell correction using self-consistent nuclear models: the non-relativistic Skyrme-Hartree-Fock approach and the relativistic mean-field model, for a number of parametrizations. All the forces applied predict a broad valley of shell stabilization around Z = 120 and N = 172-184. We also predict two broad regions of shell stabilization in hyperheavy elements with N ∼ 258 and N ∼ 308. Due to the large single-particle level density, shell corrections in the superheavy elements differ markedly from those in lighter nuclei. With increasing proton and neutron numbers, the regions of nuclei stabilized by shell effects become poorly localized in particle number, and the familiar pattern of shells separated by magic gaps is basically gone. (orig.)
Projected shell model description of N = 114 superdeformed isotone nuclei
International Nuclear Information System (INIS)
Guo, R S; Chen, L M; Chou, C H
2006-01-01
A systematic description of the yrast superdeformed (SD) bands in N 114, Z = 80-84 isotone nuclei using the projected shell model is presented. The calculated γ-ray energies, moment of inertia and M1 transitions are compared with the data for which spin is assigned. Excellent agreement with the available data for all isotones is obtained. The calculated electromagnetic properties provide a microscopic understanding of those measured nuclei. Some predictions in superdeformed nuclei are also discussed
Shell model Monte Carlo investigation of rare earth nuclei
International Nuclear Information System (INIS)
White, J. A.; Koonin, S. E.; Dean, D. J.
2000-01-01
We utilize the shell model Monte Carlo method to study the structure of rare earth nuclei. This work demonstrates the first systematic full oscillator shell with intruder calculations in such heavy nuclei. Exact solutions of a pairing plus quadrupole Hamiltonian are compared with the static path approximation in several dysprosium isotopes from A=152 to 162, including the odd mass A=153. Some comparisons are also made with Hartree-Fock-Bogoliubov results from Baranger and Kumar. Basic properties of these nuclei at various temperatures and spin are explored. These include energy, deformation, moments of inertia, pairing channel strengths, band crossing, and evolution of shell model occupation numbers. Exact level densities are also calculated and, in the case of 162 Dy, compared with experimental data. (c) 2000 The American Physical Society
Quasi-molecular states in sd-shell nuclei
International Nuclear Information System (INIS)
Kubono, S.; Ikeda, N.; Nomura, T.
1988-08-01
Quasi-molecular states near and below the threshold of the molecular configuration in sd-shell nuclei are discussed using recent experimental data with particle-gamma coincidence method and particle-particle coincidence method. Possible quasi-molecular states have been identified in 24 Mg as well as in 28 Si and 32 S. The important role of quasi-molecular states are discussed, specifically for the shape evolution of nuclei as a function of excitation energy and angular momentum. (author)
Three-body forces in p-shell nuclei
International Nuclear Information System (INIS)
Hees, A.G.M. van; Booten, J.G.L.; Glaudemans, P.W.M.
1990-01-01
Within the (0 + 1)ℎω shell-model space for p-shell nuclei we found that a schematic three-body interaction in addition to a translationally invariant two-body interaction leads to a strongly improved description of energy levels. The present three-body interaction is related to the Δ-isobar intermediate-state model of the two-pion exchange three-nucleon interaction. (orig.)
Shell-model Monte Carlo studies of nuclei
International Nuclear Information System (INIS)
Dean, D.J.
1997-01-01
The pair content and structure of nuclei near N = Z are described in the frwnework of shell-model Monte Carlo (SMMC) calculations. Results include the enhancement of J=0 T=1 proton-neutron pairing at N=Z nuclei, and the maxked difference of thermal properties between even-even and odd-odd N=Z nuclei. Additionally, a study of the rotational properties of the T=1 (ground state), and T=0 band mixing seen in 74 Rb is presented
Recent shell-model results for exotic nuclei
Directory of Open Access Journals (Sweden)
Utsuno Yusuke
2014-03-01
Full Text Available We report on our recent advancement in the shell model and its applications to exotic nuclei, focusing on the shell evolution and large-scale calculations with the Monte Carlo shell model (MCSM. First, we test the validity of the monopole-based universal interaction (VMU as a shell-model interaction by performing large-scale shell-model calculations in two different mass regions using effective interactions which partly comprise VMU. Those calculations are successful and provide a deeper insight into the shell evolution beyond the single-particle model, in particular showing that the evolution of the spin-orbit splitting due to the tensor force plays a decisive role in the structure of the neutron-rich N ∼ 28 region and antimony isotopes. Next, we give a brief overview of recent developments in MCSM, and show that it is applicable to exotic nuclei that involve many valence orbits. As an example of its applications to exotic nuclei, shape coexistence in 32Mg is examined.
Shell model truncation schemes for rotational nuclei
International Nuclear Information System (INIS)
Halse, P.; Jaqua, L.; Barrett, B.R.
1990-01-01
The suitability of the pair condensate approach for rotational states is studied in a single j = 17/2 shell of identical nucleons interacting through a quadrupole-quadrupole hamiltonian. The ground band and a K = 2 excited band are both studied in detail. A direct comparison of the exact states with those constituting the SD and SDG subspaces is used to identify the important degrees of freedom for these levels. The range of pairs necessary for a good description is found to be highly state dependent; S and D pairs are the major constituents of the low-spin ground band levels, while G pairs are needed for those in the γ-band. Energy spectra are obtained for each truncated subspace. SDG pairs allow accurate reproduction of the binding energy and K = 2 excitation energy, but still give a moment of inertia which is about 30% too small even for the lowest levels
Shell closures, loosely bound structures, and halos in exotic nuclei
International Nuclear Information System (INIS)
Saxena, G.; Singh, D.
2013-01-01
Inspired by the recent experiments indicating doubly magic nuclei that lie near the drip-line and encouraged by the success of our relativistic mean-field (RMF) plus state-dependent BCS approach to the description of the ground-state properties of drip-line nuclei, we develop this approach further, across the entire periodic table, to explore magic nuclei, loosely bound structures, and halo formation in exotic nuclei. In our RMF+BCS approach, the single-particle continuum corresponding to the RMF is replaced by a set of discrete positive-energy states for the calculations of pairing energy. Detailed analysis of the single-particle spectrum, pairing energies, and densities of the nuclei predict the unusual proton shell closures at proton numbers Z = 6, 14, 16, 34, and unusual neutron shell closures at neutron numbers N = 6, 14, 16, 34, 40, 70, 112. Further, in several nuclei like the neutron-rich isotopes of Ca, Zr, Mo, etc., the gradual filling of lowlying single-particle resonant state together with weakly bound single-particle states lying close to the continuum threshold helps accommodate more neutrons but with an extremely small increase in the binding energy. This gives rise to the occurrence of loosely bound systems of neutron-rich nuclei with a large neutron-to-proton ratio. In general, the halo-like formation, irrespective of the existence of any resonant state, is seen to be due to the large spatial extension of the wave functions for the weakly bound single-particle states with low orbital angular momentum having very small or no centrifugal barriers.
Shell closures, loosely bound structures, and halos in exotic nuclei
Energy Technology Data Exchange (ETDEWEB)
Saxena, G., E-mail: gauravphy@gmail.com [Govt. Women Engineering College, Department of Physics (India); Singh, D. [University of Rajasthan, Department of Physics (India)
2013-04-15
Inspired by the recent experiments indicating doubly magic nuclei that lie near the drip-line and encouraged by the success of our relativistic mean-field (RMF) plus state-dependent BCS approach to the description of the ground-state properties of drip-line nuclei, we develop this approach further, across the entire periodic table, to explore magic nuclei, loosely bound structures, and halo formation in exotic nuclei. In our RMF+BCS approach, the single-particle continuum corresponding to the RMF is replaced by a set of discrete positive-energy states for the calculations of pairing energy. Detailed analysis of the single-particle spectrum, pairing energies, and densities of the nuclei predict the unusual proton shell closures at proton numbers Z = 6, 14, 16, 34, and unusual neutron shell closures at neutron numbers N = 6, 14, 16, 34, 40, 70, 112. Further, in several nuclei like the neutron-rich isotopes of Ca, Zr, Mo, etc., the gradual filling of lowlying single-particle resonant state together with weakly bound single-particle states lying close to the continuum threshold helps accommodate more neutrons but with an extremely small increase in the binding energy. This gives rise to the occurrence of loosely bound systems of neutron-rich nuclei with a large neutron-to-proton ratio. In general, the halo-like formation, irrespective of the existence of any resonant state, is seen to be due to the large spatial extension of the wave functions for the weakly bound single-particle states with low orbital angular momentum having very small or no centrifugal barriers.
Shell-model results in fp and fpg9/2 spaces for 61,63,65Co isotopes
International Nuclear Information System (INIS)
Srivastava, P. C.; Kota, V. K. B.
2011-01-01
Low-lying spectra and several high-spin states of odd-even 61,63,65 Co isotopes are calculated in two different shell-model spaces. First set of calculations have been carried out in fp-shell valence space (full fp space for 63,65 Co and a truncated one for 61 Co) using two recently derived fp-shell interactions, namely GXPF1A and KB3G, with 40 Ca as core. Similarly, the second set of calculations have been performed in fpg 9/2 valence space using an fpg effective interaction due to Sorlin et al., with 48 Ca as core and imposing a truncation. It is seen that the results of GXPF1A and KB3G are reasonable for 61,63 Co. For 65 Co, shell-model results show that the fpg interaction adopted in the study is inadequate and also points out that it is necessary to include orbitals higher than 1g 9/2 for neutron-rich Co isotopes.
Resonances in collisions between S-D shell nuclei
International Nuclear Information System (INIS)
Betts, R.R.
1984-01-01
Experimental evidence relating to the existence of resonances in collisions between s-d shell nuclei will be reviewed. The determination of the spins and spectroscopic properties of some of these resonances will be discussed. The behaviour of both the resonance and background cross-sections will be compared with model expectations. Some future directions in this area of study will be indicated and the relationship of this work to other results briefly discussed. (author)
Clustering aspects of sd shell nuclei studied by AMD
Energy Technology Data Exchange (ETDEWEB)
Kimura, Masaaki [Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502 (Japan); Taniguchi, Yasutaka [Department of Physics, Kyoto University, Kitashirakawa, Kyoto 606-8502 (Japan); En' yo, Yoshiko [Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502 (Japan); Horiuchi, Hisashi [Department of Physics, Kyoto University, Kitashirakawa, Kyoto 606-8502 (Japan)
2006-10-10
The new clustering aspects of sd-shell nuclei found by the recent application of the antisymmetrized molecular dynamics are reported. In this paper we present two topics, 'superdeformed band of {sup 32}S and {sup 16}O + {sup 16}O clustering' and 'molecular-orbital and di-nuclei states in {sup 22}Ne'. In the first topic, it will be shown that the superdeformed band of 32S has a considerable amount of {sup 16}O + {sup 16}O cluster component, and can be regarded as to belong to a family of the {sup 16}O + {sup 16}O molecular bands. In the second topic, the presence of the molecularorbital band which has an {alpha} + {sup 16}O cluster core surrounded by two covalently neutrons is suggested together with an {alpha} + {sup 18}O di-nuclei band.
Clustering aspects of sd shell nuclei studied by AMD
International Nuclear Information System (INIS)
Kimura, Masaaki; Taniguchi, Yasutaka; En'yo, Yoshiko; Horiuchi, Hisashi
2006-01-01
The new clustering aspects of sd-shell nuclei found by the recent application of the antisymmetrized molecular dynamics are reported. In this paper we present two topics, 'superdeformed band of 32 S and 16 O + 16 O clustering' and 'molecular-orbital and di-nuclei states in 22 Ne'. In the first topic, it will be shown that the superdeformed band of 32S has a considerable amount of 16 O + 16 O cluster component, and can be regarded as to belong to a family of the 16 O + 16 O molecular bands. In the second topic, the presence of the molecularorbital band which has an α + 16 O cluster core surrounded by two covalently neutrons is suggested together with an α + 18 O di-nuclei band
Probing the Evolution of the Shell Structures in Exotic Nuclei
International Nuclear Information System (INIS)
De Angelis, Giacomo
2008-01-01
Magic numbers are a key feature in finite Fermion systems since they are strongly related to the underlying mean field. The size of the shell gaps and their evolution far from stability can be linked to the shape and symmetry of the nuclear mean field. Moreover the study of nuclei with large neutron/proton ratio allow to probe the density dependence of the effective interaction. Changes of the nuclear density and size in nuclei with increasing N/Z ratios are expected to lead to different nuclear symmetries and excitations. In this contribution I will discuss some selected examples which show the big potential of stable beams and of binary reactions for the study of the properties of the neutron-rich nuclear many body systems.
Unified description of pf-shell nuclei by the Monte Carlo shell model calculations
Energy Technology Data Exchange (ETDEWEB)
Mizusaki, Takahiro; Otsuka, Takaharu [Tokyo Univ. (Japan). Dept. of Physics; Honma, Michio
1998-03-01
The attempts to solve shell model by new methods are briefed. The shell model calculation by quantum Monte Carlo diagonalization which was proposed by the authors is a more practical method, and it became to be known that it can solve the problem with sufficiently good accuracy. As to the treatment of angular momentum, in the method of the authors, deformed Slater determinant is used as the basis, therefore, for making angular momentum into the peculiar state, projected operator is used. The space determined dynamically is treated mainly stochastically, and the energy of the multibody by the basis formed as the result is evaluated and selectively adopted. The symmetry is discussed, and the method of decomposing shell model space into dynamically determined space and the product of spin and isospin spaces was devised. The calculation processes are shown with the example of {sup 50}Mn nuclei. The calculation of the level structure of {sup 48}Cr with known exact energy can be done with the accuracy of peculiar absolute energy value within 200 keV. {sup 56}Ni nuclei are the self-conjugate nuclei of Z=N=28. The results of the shell model calculation of {sup 56}Ni nucleus structure by using the interactions of nuclear models are reported. (K.I.)
Electron-capture Rates for pf-shell Nuclei in Stellar Environments and Nucleosynthesis
Suzuki, Toshio; Honma, Michio; Mori, Kanji; Famiano, Michael A.; Kajino, Toshitaka; Hidakai, Jun; Otsuka, Takaharu
Gamow-Teller strengths in pf-shell nuclei obtained by a new shell-model Hamltonian, GXPF1J, are used to evaluate electron-capture rates in pf-shell nuclei at stellar environments. The nuclear weak rates with GXPF1J, which are generally smaller than previous evaluations for proton-rich nuclei, are applied to nucleosynthesis in type Ia supernova explosions. The updated rates are found to lead to less production of neutron-rich nuclei such as 58Ni and 54Cr, thus toward a solution of the problem of over-production of neutron-rich isotopes of iron-group nuclei compared to the solar abundance.
Clustering of 1p-shell nuclei in the framework of the shell model
International Nuclear Information System (INIS)
Kwasniewicz, E.
1991-01-01
The two- and three-fragment clustering of the 1p-shell nuclei has been studied in the framework of the shell model. The absolute probabilities of the required types of clustering in a given nucleus have been obtained by projecting its realistic shell-model wavefunction onto the suitable subspace of the orthonormal, completely antisymmetric two- or three-cluster states. With the aid of these data the selectivity in population of final states produced in multinucleon transfer reactions has been discussed. This problem has also been considered in the approach where the exchange of nucleons between clusters has been neglected. This has enabled to demonstrate the role of the complete antisymmetrization in predicting the intensities of states populated in multinucleon transfer reactions. The compact theory of the multinucleon one- and two-cluster spectroscopic amplitudes has been formulated. The examples of studying the nuclear structure and reactions with the aid of these spectroscopic amplitudes have been presented. (author)
Spectra theory for nuclei with closed shells (1962)
International Nuclear Information System (INIS)
Gillet, V.
1962-01-01
A unified theory for the spectra of nuclei with closed shells, based on the elementary particle-hole excitation of these systems, is applied to a study of carbon-12, oxygen-16 and calcium-40. Two approximations are made. The first consists in diagonalizing the residual two-body interaction in a limited sub-space having one particle and one hole configurations. Its validity depends on the high energy necessary for exciting a particle-hole pair. The second approximation consists in re-summing the infinite sub-series of the particle-hole diagrams. It is equivalent to the Hartree-Fock method depending on the time, or to Quasi-Boson method. Its domain of validity in the nuclear case is not thoroughly Understood. The summed diagrams are preponderant at the high density limit, when the nuclear density is about unity. The violation of the Pauli principle in this approximation is only justified if the number of excited pairs is small with respect to the number of particle states available; in the case of light nuclei the degeneracies of the shells are small. Nevertheless this approximation, which postulates the existence of an average nuclear field, varying slowly with time with respect to the nucleons periods has the merit of being self-consistent, of giving orthogonal proper states in the non-physical state of the mass centre, and of improving the calculation of the summation rules. In order to determine and to limit the role of phenomenology in the results obtained using these approximations, a maximum amount of experimental data is calculated. By applying method of least squares to fourteen energy levels of oxygen and carbon, the region of optimum agreement in the effective interaction parameters is determined. This region is in part a function of the numerical approximations made. We hope that it will keep its significance when the theory is improved. It is compatible with certain characteristics of free nucleon-nucleon scattering. The present research favours the
Beta-decay strength and isospin mixing studies in the sd and fp-shells
International Nuclear Information System (INIS)
Jokinen, A.; Aeystoe, J.; Dendooven, P.; Honkanen, A.; Lipas, P.; Peraejaervi, K.; Oinonen, M.; Siiskonen, T.
1998-01-01
We have studied beta decays of M T 41 Ti shows a large, 10(8) %, isospin mixing of IAS and the Gamow-Teller strength is observed to be quenched by a factor of q 2 =0.64. These results can be reproduced qualitatively in our shell model calculations. We have observed for the first time proton and gamma decay of the isobaric analogue state in 23 Mg. Our results on the isospin mixing of the isobaric analogue state agrees well with the shell model calculations. The obtained proton branch of the IAS is used to extract the transition strength for the reaction 22 Na(p,γ) 23 Mg
Cluster configuration and super deformation in f-p shell nuclei
International Nuclear Information System (INIS)
Shanmugam, G.; Santhosh Kumar, S.; Chintalapudi, S.N.; Benjamin, G.A.
1996-01-01
The aim of this work was to perform three oxygen clusters calculation for excited 48 Cr, to do a Cranked Nilsson Strutinsky calculations for it and to compare the results so as to look for super deformations
Statistical fluctuations of electromagnetic transition intensities in pf-shell nuclei
International Nuclear Information System (INIS)
Hamoudi, A.; Nazmitdinov, R.G.; Shakhaliev, E.; Alhassid, Y.
2000-01-01
We study the fluctuation properties of ΔT = 0 electromagnetic transition intensities in A ∼ 60 nuclei within the framework of the interacting shell model, using a realistic effective interaction for pf-shell nuclei with a 56 Ni core. It is found that the B(E2) and the ΔJ ≠ 0 distributions are well described by the Gaussian orthogonal ensemble of random matrices (Porter-Thomas distribution) independently of the isobaric quantum number T Z . However, the statistics of the B(M1) transitions with Δ = 0 are sensitive to T Z : T Z = 1 nuclei exhibit a Porter-Thomas distribution, while a significant deviation from the GOE statistics is observed for self-conjugate nuclei (T Z = 0). Similar results are found for A = 22 sd-shell nuclei
High-spin states in sd-shell nuclei
International Nuclear Information System (INIS)
Poel, C.J. van der.
1982-01-01
A systematic picture of the structure of high-spin states in the mass range A = 29 - 41 is developed on the basis of experimental results for the nuclei 34 Cl, 38 K and 39 K. It is shown that for 34 Cl the difficulties induced by the relatively low cross section can be overcome. Combination of the data obtained from a γ-γ coincidence experiment with the 24 Mg + 12 C reaction, using the LACSS, and from threshold measurements in the 31 P + α reaction, establishes an unambiguous level scheme. By means of accurate angular-distribution measurements unambiguous spin and parity assignments are made to the high-spin levels. From the results a rather simple shell-model picture for the structure of the high-spin states evolves. Several authors have published experimental work on high-spin states in 39 K, with seriously conflicting conclusions, however, for the spin-parity assignments. The powerful coincidence set-up with the LACSS enables a discrimination between the conflicting results from the previous studies. In this way, unambiguous, model-independent, spin-parity assignments to the high-spin levels are established. Highly selective experimental methods are used to identify the high-spin states of 38 K. It is shown that with a pulsed beam in the reaction 24 Mg + 16 O advantage can be taken of the presence of a long-lived high-spin isomeric level in this nucleus. The gamma-decay of the isomer is extensively studied. With the pulsed beam, also some states above the isomer could be located. The subsequent use of two Compton-suppression spectrometers in a γ-γ coincidence experiment reveals a number of high-spin levels at higher excitation energies. (Auth.)
Decay of giant resonances states in radiative pion capture by 1p shell nuclei
International Nuclear Information System (INIS)
Dogotar, G.E.
1978-01-01
The decay of the giant resonance states excited in tthe radiative pion capture on the 9 Be, 11 B, 13 C and 14 N nuclei is considered in the shell model with intermediate coupling. It is shown that the excited states in the daughter nuclei (A-1, Z-1) are mainly populated by intermediate states with spin by two units larger than the spin of the target nuclei. Selected coincidence experiments are proposed
Shell and pairing effects in spherical nuclei close to the nucleon drip lines
International Nuclear Information System (INIS)
Beiner, M.; Lombard, R.J.
1975-01-01
The unstability against nucleon emission of light and medium exotic spherical nuclei is investigated systematically using an extended version of the energy density formalism which reproduces correctly shell and pairing effects in stable nuclei. The reliability of the predictions of this microscopic, self-consistent and weakly parametrized model should not decrease significantly with the distance of the nuclei from the β-stability line, what is not the case for conventional mass formulae or mass tables [fr
Symmetry-dictated trucation: Solutions of the spherical shell model for heavy nuclei
International Nuclear Information System (INIS)
Guidry, M.W.
1992-01-01
Principles of dynamical symmetry are used to simplify the spherical shell model. The resulting symmetry-dictated truncation leads to dynamical symmetry solutions that are often in quantitative agreement with a variety of observables. Numerical calculations, including terms that break the dynamical symmetries, are shown that correspond to shell model calculations for heavy deformed nuclei. The effective residual interaction is simple, well-behaved, and can be determined from basic observables. With this approach, we intend to apply the shell model in systematic fashion to all nuclei. The implications for nuclear structure far from stability and for nuclear masses and other quantities of interest in astrophysics are discussed
Structure of exotic nuclei by large-scale shell model calculations
International Nuclear Information System (INIS)
Utsuno, Yutaka; Otsuka, Takaharu; Mizusaki, Takahiro; Honma, Michio
2006-01-01
An extensive large-scale shell-model study is conducted for unstable nuclei around N = 20 and N = 28, aiming to investigate how the shell structure evolves from stable to unstable nuclei and affects the nuclear structure. The structure around N = 20 including the disappearance of the magic number is reproduced systematically, exemplified in the systematics of the electromagnetic moments in the Na isotope chain. As a key ingredient dominating the structure/shell evolution in the exotic nuclei from a general viewpoint, we pay attention to the tensor force. Including a proper strength of the tensor force in the effective interaction, we successfully reproduce the proton shell evolution ranging from N = 20 to 28 without any arbitrary modifications in the interaction and predict the ground state of 42Si to contain a large deformed component
Mean field theory of nuclei and shell model. Present status and future outlook
International Nuclear Information System (INIS)
Nakada, Hitoshi
2003-01-01
Many of the recent topics of the nuclear structure are concerned on the problems of unstable nuclei. It has been revealed experimentally that the nuclear halos and the neutron skins as well as the cluster structures or the molecule-like structures can be present in the unstable nuclei, and the magic numbers well established in the stable nuclei disappear occasionally while new ones appear. The shell model based on the mean field approximation has been successfully applied to stable nuclei to explain the nuclear structure as the finite many body system quantitatively and it is considered as the standard model at present. If the unstable nuclei will be understood on the same model basis or not is a matter related to fundamental principle of nuclear structure theories. In this lecture, the fundamental concept and the framework of the theory of nuclear structure based on the mean field theory and the shell model are presented to make clear the problems and to suggest directions for future researches. At first fundamental properties of nuclei are described under the subtitles: saturation and magic numbers, nuclear force and effective interactions, nuclear matter, and LS splitting. Then the mean field theory is presented under subtitles: the potential model, the mean field theory, Hartree-Fock approximation for nuclear matter, density dependent force, semiclassical mean field theory, mean field theory and symmetry, Skyrme interaction and density functional, density matrix expansion, finite range interactions, effective masses, and motion of center of mass. The subsequent section is devoted to the shell model with the subtitles: beyond the mean field approximation, core polarization, effective interaction of shell model, one-particle wave function, nuclear deformation and shell model, and shell model of cross shell. Finally structure of unstable nuclei is discussed with the subtitles: general remark on the study of unstable nuclear structure, asymptotic behavior of wave
Gross shell structure at high spin in heavy nuclei
International Nuclear Information System (INIS)
Deleplanque, Marie-Agnes; Frauendorf, Stefan; Pashkevich, Vitaly V.; Chu, S.Y.; Unzhakova, Anja
2003-01-01
Experimental nuclear moments of inertia at high spins along the yrast line have been determined systematically and found to differ from the rigid-body values. The difference is attributed to shell effect and these have been calculated microscopically. The data and quantal calculations are interpreted by means of the semiclassical Periodic Orbit Theory. From this new perspective, features in the moments of inertia as a function of neutron number and spin, as well as their relation to the shell energies can be understood. Gross shell effects persist up to the highest angular momenta observed
Elementary isovector spin and orbital magnetic dipole modes revisited in the shell model
International Nuclear Information System (INIS)
Richter, A.
1988-08-01
A review is given on the status of mainly spin magnetic dipole modes in some sd- and fp-shell nuclei studied with inelastic electron and proton scattering, and by β + -decay. Particular emphasis is also placed on a fairly new, mainly orbital magnetic dipole mode investigated by high-resolution (e,e') and (p,p') scattering experiments on a series of fp-shell nuclei. Both modes are discussed in terms of the shell model with various effective interactions. (orig.)
Nuclear structure of s-d shell nuclei: what is new?
International Nuclear Information System (INIS)
Shanmugam, G.
1995-01-01
In this paper the shape evolution of the even-even s-d shell nuclei with temperature and spin is studied using Landau theory of phase transitions. The most important thermal fluctuations are incorporated in this study. The ground state pairing is also included in the calculations. Both the summation and Strutinsky methods are used for extracting the Landau constants. Both yield qualitatively similar results. To conclude, Landau theory of phase transitions can be effectively and economically used to study the structure of excited s-d shell nuclei. 10 refs., 2 tabs., 8 figs
Energy Technology Data Exchange (ETDEWEB)
Pasechnik, M V
1978-01-01
Major results of investigations into the shell structure of deformed nuclei with the number of neutrons of approximately 100, as well as new isotopic effects in the inelastic scattering of fast neutrons with nuclei are reported. The experiments conducted at the WWR-M research reactor have shown a substantial dependence of the nuclear excited energy-level density on the mass number and the number of neutrons. The fact resulted in a conclusion that the deformed nuclei possess filled shells, that was an incentive to revise the whole nuclear shell concept. In particular it was established that the property of magicity rests not only on the sphericity of nuclei but it may be also observed in strongly deformed nuclei. The isotope-spin dependence of the nuclear potential was studied at the AG-5 pulse electrostatic generator. The parameters of the potential were determined by comparing the experimental data on inelastic scattering and polarization of fast neutrons by nuclei from /sup 48/Ti to /sup 209/Bi with the calculations in terms of the optical model. Simple correlations were established between the optical potential and the nucleus asymmetry parameter ..cap alpha..=N-Z/A in wide ranges of mass numbers and neutron energy.
Binding energies of sd-shell nuclei with a realistic effective Hamiltonian
International Nuclear Information System (INIS)
Dalton, B.J.; Vary, J.P.; Baldridge, W.J.
1977-01-01
The nuclear shell model with a second-order effective Hamiltonian derived within Brueckner theory from the free nucleon-nucleon interaction is shown to yield accurate binding energies of nuclei with 16 < A < 40. This agreement is obtained by choosing the spectrum of low-lying unoccupied orbitals in a justified manner and, when necessary, by employing a statistical method to approximate the lowest eigenvalue of very large shell-model diagonalizations
Shell effects on the E1 moments of Ra-Th nuclei
International Nuclear Information System (INIS)
Leander, G.A.
1984-01-01
Large systematic shell effects on intrinsic E1 moments are found, which should modulate any E1 moment induced by β 3 deformation. The calculated shell effects can explain an emerging trend for E1 data in Ra-Th nuclei, if and only if the gross β 3 -induced polarization of finite nuclear matter goes in the same direction as the lightning rod effect. 16 references
Quenching of the Gamow-Teller matrix element in closed LS-shell-plus-one nuclei
International Nuclear Information System (INIS)
Towner, I.S.
1989-06-01
It is evident that nuclear Gamow-Teller matrix elements determined from β-decay and charge-exchange reactions are significantly quenched compared to simple shell-model estimates based on one-body operators and free-nucleon coupling constants. Here we discuss the theoretical origins of this quenching giving examples from light nuclei near LS-closed shells, such as 16 0 and 40 Ca. (Author) 12 refs., 2 tabs
Casten, R. F.; Cakirli, R. B.
2009-03-01
Understanding the development of configuration mixing, coherence, collectivity, and deformation in nuclei is one of the crucial challenges in nuclear structure physics, and one which has become all the more important with the advent of next generation facilities for the study of exotic nuclei. We will discuss recent work on phase/shape transitional behavior in nuclei, and the role of changes in sub-shell structure in mediating such transitional regions. We will also discuss a newly found, much deeper, link between nuclear structure and nuclear binding energies.
Triaxiality and alternating M1 strengths in f-p-g shell nuclei
Energy Technology Data Exchange (ETDEWEB)
Tabor, S L; Johnson, T D; Holcombe, J W; Womble, P C; Doring, J; Nazarewicz, W [Florida State Univ., Tallahassee, FL (United States). Dept. of Physics
1992-08-01
The appearance of alternating patterns in B(M1) strengths in f-p-g shell nuclei is surveyed. The M1 alternations in a sequence of N= 41 isotones, in conjunction with particle-rotor model calculations, is shown to provide information about changing {gamma} deformation. In addition to other odd-A nuclei, several odd-odd nuclei are shown to exhibit alternating B(M1) values and signature inversion. alternations have also been reported in a 4 quasiparticle band in {sup 86}Zr, where they have been interpreted in terms of the interacting boson model. (author). 15 refs., 1 tab., 6 figs.
Symplectic no-core shell-model approach to intermediate-mass nuclei
Tobin, G. K.; Ferriss, M. C.; Launey, K. D.; Dytrych, T.; Draayer, J. P.; Dreyfuss, A. C.; Bahri, C.
2014-03-01
We present a microscopic description of nuclei in the intermediate-mass region, including the proximity to the proton drip line, based on a no-core shell model with a schematic many-nucleon long-range interaction with no parameter adjustments. The outcome confirms the essential role played by the symplectic symmetry to inform the interaction and the winnowing of shell-model spaces. We show that it is imperative that model spaces be expanded well beyond the current limits up through 15 major shells to accommodate particle excitations, which appear critical to highly deformed spatial structures and the convergence of associated observables.
Zeng, ShaoJu; Li, Jia; Zhang, XinWen; Zuo, MingXue
2007-01-01
The distribution of Met-enkephalin (ENK), substance P (SP) and serotonin (5-HT) differs between the core and shell regions of the mesencephalic and diencephalic auditory nuclei of the turtle [Belekhova et al., 2002]. These neurochemical distinctions are also found in other tetrapods (mammals, birds and amphibians). The distribution of ENK, SP and 5-HT was examined in the core and shell regions of both mesencephalic and diencephalic auditory nuclei, and in the telencephalic auditory areas of Bengalese finches (Lonchura striata) and mice (Mus musculus), as well as in corresponding auditory areas in toads (Bufo bufo). ENK, SP and 5-HT immunoreactive fibers and perikarya were largely absent from the core regions of both mesencephalic and diencephalic auditory nuclei, in comparison with the shell regions of mice and Bengalese finches. In the toad, however, this pattern was observed in the mesencephalic auditory nucleus, but not in the diencephalic auditory areas. ENK and SP immunoreactive perikarya were detected in the telencephalic auditory area of mice, whereas no ENK, SP or 5-HT immunolabeling was observed in the telencephalic auditory area (Field L) of Bengalese finches. These findings are discussed in terms of the evolution of the core-and-shell organization of auditory nuclei of tetrapods. Copyright 2007 S. Karger AG, Basel.
Alphaspectroscopic amplitudes for nuclei in the lower half of the sd-shell
International Nuclear Information System (INIS)
Conze, M.
1976-01-01
Alpha-spectroscopic amplitudes and factors were calculated with the aid of the shell model for nuclei with mass numbers between A = 16 and A = 24. For transitions to levels belonging to the ground state band of the residual nucleus, the findings confirm the predictions based on the SU(3) model. (orig.) [de
Collectivity in heavy nuclei in the shell model Monte Carlo approach
International Nuclear Information System (INIS)
Özen, C.; Alhassid, Y.; Nakada, H.
2014-01-01
The microscopic description of collectivity in heavy nuclei in the framework of the configuration-interaction shell model has been a major challenge. The size of the model space required for the description of heavy nuclei prohibits the use of conventional diagonalization methods. We have overcome this difficulty by using the shell model Monte Carlo (SMMC) method, which can treat model spaces that are many orders of magnitude larger than those that can be treated by conventional methods. We identify a thermal observable that can distinguish between vibrational and rotational collectivity and use it to describe the crossover from vibrational to rotational collectivity in families of even-even rare-earth isotopes. We calculate the state densities in these nuclei and find them to be in close agreement with experimental data. We also calculate the collective enhancement factors of the corresponding level densities and find that their decay with excitation energy is correlated with the pairing and shape phase transitions. (author)
Potentials for calculating both parity states in p-shell nuclei
International Nuclear Information System (INIS)
Resler, D.A.
1989-01-01
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: 4 He, /sup 5,6,7,8/Li, 8 Be, /sup 13,14/C, and 13 N. 34 refs., 9 figs., 3 tabs
Shell structures and chaos in nuclei and large metallic clusters
International Nuclear Information System (INIS)
Heiss, W.D.; University of the Witwatersrand, Johannesburg; Nazmitdinov, R.G.; Radu, S.; University of the Witwatersrand, Johannesburg
1995-01-01
A reflection-asymmetric deformed oscillator potential is analyzed from the classical and quantum mechanical point of view. The connection between occurrence of shell structures and classical periodic orbits is studied using the ''removal of resonances method'' in a classical analysis. In this approximation, the effective single particle potential becomes separable and the frequencies of the classical trajectories are easily determined. It turns out that the winding numbers calculated in this way are in good agreement with the ones found from the corresponding quantum mechanical spectrum using the particle number dependence of the fluctuating part of the total energy. When the octupole term is switched on it is found that prolate shapes are stable against chaos and can exhibit shells where spherical and oblate cases become chaotic. An attempt is made to explain this difference in the quantum mechanical context by looking at the distribution of exceptional points which results from the matrix structure of the respective Hamiltonians. In a similar way we analyze the modified Nilsson model and discuss its consequences for metallic clusters. (orig.)
Coulomb energy differences in mirror nuclei
International Nuclear Information System (INIS)
Lenzi, Silvia M
2006-01-01
By comparing the excitation energies of analogue states in mirror nuclei, several nuclear structure properties can be studied as a function of the angular momentum up to high spin states. They can be described in the shell model framework by including electromagnetic and nuclear isospin-non-conserving interactions. Calculations for the mirror energy differences in nuclei of the f 7/2 shell are described and compared with recent experimental data. These studies are extended to mirror nuclei in the upper sd and fp shells
Studies of short-lived nuclei in the proximity of closed shells
International Nuclear Information System (INIS)
Omtvedt, J.P.
1995-01-01
In this work the structure of 84,85 Se at the closed N=50 neutron shell, and the 132 Sb, 132 Sn, and 134 Te nuclei, at the doubly closed N=82,Z=50 shells, was studied. The experiments were performed at the OSIRIS fission product mass separator at Studsvik, Sweden. The excited levels of the studied nuclei were populated in β decay. The sources were produced in fission of 235 U in the OSIRIS combined target and ion source. The nuclei were studied by standard nuclear spectroscopy measuring techniques: Singles γ spectra and γγ-coincidence data were obtained. In addition γγ(θ) angular correlation and βγγ(t) triple coincidence ''fast-timing'' ,measurements were performed on the nuclei in the 132 Sn (N=82,Z=50) region. Detailed level schemes for the 84,85 Se, 132 Sb, 132 Sn, 132 Te nuclei were built, greatly improvi our knowledge of the structure of these nuclei. The experimentally deduced transition rates and multipole mixing ratios of the studied 132 Sn region nuclei were compared to theoretical calculations within the random phase approximation framework and related models. Particular attention was paid to the collective properties of nuclei in the 132 Sn region, parametrized by the electrical octupole effective charge. A range of general software spectroscopic tools were developed for the purpose of analysing the experimental data. This included a program, Yggdrasil, which for the first time allowed a complete two-dimensional γγ-coincidence matrix to be analysed on ordinary ''small'' personal computers (PCs). 49 refs., 10 figs., 2 tabs
Studies of short-lived nuclei in the proximity of closed shells
Energy Technology Data Exchange (ETDEWEB)
Omtvedt, J.P.
1995-12-31
In this work the structure of {sup 84,85}Se at the closed N=50 neutron shell, and the {sup 132}Sb, {sup 132}Sn, and {sup 134}Te nuclei, at the doubly closed N=82,Z=50 shells, was studied. The experiments were performed at the OSIRIS fission product mass separator at Studsvik, Sweden. The excited levels of the studied nuclei were populated in {beta} decay. The sources were produced in fission of {sup 235}U in the OSIRIS combined target and ion source. The nuclei were studied by standard nuclear spectroscopy measuring techniques: Singles {gamma} spectra and {gamma}{gamma}-coincidence data were obtained. In addition {gamma}{gamma}({theta}) angular correlation and {beta}{gamma}{gamma}(t) triple coincidence ``fast-timing`` ,measurements were performed on the nuclei in the {sup 132}Sn (N=82,Z=50) region. Detailed level schemes for the {sup 84,85}Se, {sup 132}Sb,{sup 132}Sn, {sup 132}Te nuclei were built, greatly improvi our knowledge of the structure of these nuclei. The experimentally deduced transition rates and multipole mixing ratios of the studied {sup 132}Sn region nuclei were compared to theoretical calculations within the random phase approximation framework and related models. Particular attention was paid to the collective properties of nuclei in the {sup 132}Sn region, parametrized by the electrical octupole effective charge. A range of general software spectroscopic tools were developed for the purpose of analysing the experimental data. This included a program, Yggdrasil, which for the first time allowed a complete two-dimensional {gamma}{gamma}-coincidence matrix to be analysed on ordinary ``small`` personal computers (PCs). 49 refs., 10 figs., 2 tabs.
Projected shell model study of yrast states of neutron-deficient odd-mass Pr nuclei
International Nuclear Information System (INIS)
Ibanez-Sandoval, A.; Ortiz, M. E.; Velazquez, V.; Galindo-Uribarri, A.; Hess, P. O.; Sun, Y.
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 125,127,129,131,133 Pr 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.
Parity dependence in the optical potential of sd-shell nuclei
International Nuclear Information System (INIS)
Ferrero, J.L.; Ruiz, J.A.; Bilwes, B.; Bilwes, R.
1989-01-01
Elastic scattering between sd-shell nuclei differing by one, two, three and four nucleons has been measured. The oscillating pattern of the angular distributions, when it is observed, is attributed to the interference between direct elastic scattering and elastic transfer. Explicit DWBA treatment of the elastic transfer or parity dependent real potential analysis allow both a good reproduction of the data. The sign and the importance of the parity potential deduced by fitting the data are in good agreement with the predictions of microscopic calculations in the two centre shell-model
Nuclear charge radii of the 1fsub(7/2) shell nuclei from muonic atoms
International Nuclear Information System (INIS)
Wohlfahrt, H.D.
1979-01-01
Muonic X-ray of medium-weight nuclei have been performed in recent years by the Los Alamos muonic X-ray group, using the high intensity muon beam available at the LAMPF 800 MeV proton accelerator. These studies, which together include all stable 1fsub(7/2) neutron shell nuclei, provide information about the proton core polarization due to the successive addition of neutrons for the proton cores Z = 20 (Ca), 22 (Ti), 24(Cr), 26(Fe) and 28(Ni). In addition, these studies, which represent the first systematic investigations of isotone shifts, provide the opportunity to compare the core polarization caused by protons with core polarization caused by neutrons in the same (1fsub(7/2)) shell. (KBE)
International Nuclear Information System (INIS)
Hamoudi, A.; Shahaliev, E.; Nazmitdinov, R. G.; Alhassid, Y.
2002-01-01
We study the fluctuation properties of ΔT=0 electromagnetic transition intensities and electromagnetic moments in A∼60 nuclei within the framework of the interacting shell model, using a realistic effective interaction for pf-shell nuclei with a 56 Ni core. The distributions of the transition intensities and of the electromagnetic moments are well described by the Gaussian orthogonal ensemble of random matrices. In particular, the transition intensity distributions follow a Porter-Thomas distribution. When diagonal matrix elements (i.e., moments) are included in the analysis of transition intensities, the distributions remain Porter-Thomas except for the isoscalar M1. This deviation is explained in terms of the structure of the isoscalar M1 operator
Structure of neutron-rich nuclei around the N = 50 shell-gap closure
Faul, T.; Duchêne, G.; Thomas, J.-C.; Nowacki, F.; Huyse, M.; Van Duppen, P.
2010-04-01
The structure of neutron-rich nuclei in the vicinity of 78Ni have been investigated via the β-decay of 71,73,75Cu isotopes (ISOLDE, CERN). Experimental results have been compared with shell-model calculations performed with the ANTOINE code using a large (2p3/21f5/22p1/21g9/2) valence space and a 56/28Ni28 core.
(p,3He) reactions on 1p shell nuclei at 41 and 45 MeV
International Nuclear Information System (INIS)
Rapp, V.
1982-01-01
In the present thesis the (p, 3 He) reactions on target nuclei of the 1p shell were studied. The measurements were performed at the isochronous cyclotron of the KFA Juelich. Angular distribution at 41 and 45 MeV to residual nuclear states in 7 Li, 8 Be, 9 Be, 10 B, 11 B, 12 C, 13 C, and 14 N. were evaluated. (orig.) [de
The threshold anomaly in the interaction of s-d shell nuclei
International Nuclear Information System (INIS)
Bilwes, B.
1990-01-01
The energy dependence of the potential near the Coulomb barrier is studied by precise measurements of elastic scattering and quasi elastic reactions between s-d shell nuclei. The analyses with semi-microscopic (M3Y-folding model) and microscopic (closure approximation model) potentials allow us to demonstrate the generality of the threshold anomaly and the ability of these models to well reproduce the experimental data
Fragmentation of stretched spin strength in N=Z sd-shell nuclei
International Nuclear Information System (INIS)
Carr, J.A.; Bloom, S.D.; Petrovich, F.; Philpott, R.J.
1992-01-01
Calculations have been performed to explore the effect of configuration mixing in a large basis on the fragmentation of ''stretched'' M6 strength in the sd-shell nuclei 20 Ne, 24 Mg, 28 Si, 32 S, and 36 Ar. This work elaborates on results for 28 Si given previously, extends those calculations to neighboring N=Z nuclei with the same basis restriction (one particle in the 1f 7/2 orbit and up to four particles in the 1d 3/2 orbit) used in that earlier paper, and examines all self-conjugate sd-shell nuclei in a basis with one particle in the 1f 7/2 orbit and unrestricted occupancy of the sd-shell orbits. It is found that configuration mixing in a large basis reproduces interesting features of the spectrum for 28 Si and 32 S and gives an improved description of other properties of the observed 6 - states, but fails to describe the observed spectrum in 24 Mg. Emphasis is placed on the location of additional observable fragments of the M6 response
Directory of Open Access Journals (Sweden)
Minkov N.
2016-01-01
Full Text Available We study the effects of quadrupole-octupole deformations on the energy and magnetic properties of high-K isomeric states in even-even heavy and superheavy nuclei. The neutron two-quasiparticle (2qp isomeric energies and magnetic dipole moments are calculated within a deformed shell model with the Bardeen-Cooper- Schrieffer (BCS pairing interaction over a wide range of quadrupole and octupole deformations. We found that in most cases the magnetic moments exhibit a pronounced sensitivity to the octupole deformation, while the 2qp energies indicate regions of nuclei in which the presence of high-K isomeric states may be associated with the presence of octupole softness or even with octupole deformation. In the present work we also examine the influence of the BCS pairing strength on the energy of the blocked isomer configuration. We show that the formation of 2qp energy minima in the space of quadrupole-octupole and eventually higher multipolarity deformations is a subtle effect depending on nuclear pairing correlations.
Spectroscopic information on light halo - nuclei within the framework of multiparticle shell model
International Nuclear Information System (INIS)
Khaydarov, R.R.
2004-09-01
Aim of the inquiry: to develop the potential approach within the framework of multiparticle shell model; to obtain analytical expressions for a wave function and equations for widths off sub-barrier resonance states; to apply the theoretical approach for obtaining properties of 5 He, 5 Li, 8 B and 11 N nuclei; to estimate values of root-mean-square radiuses, radial density of nucleons, magnetic dipole and electrical quadrupole moments and spectroscopic information for 8 B and 8 Li with use of a method of expansion on functions of Storm - Liouville; to estimate the contribution of 2p - shell of 13 C and process of exchange replacement to the astrophysical S-factor of 13 C (α, n) 16 O reaction. Method of the research: theoretical approaches within the framework of multiparticle shell model. Achieved results and their novelty: new theoretical approach allowing to describe correctly the experimental static characteristics of sub-barrier one-particle resonance states in of 5 He, 5 Li, 8 B and 11 N light nuclei has been developed. Structure of 8 B and 8 Li light mirror nuclei with use of the approach for the description of one-particle resonance states based on the method of expansion on functions of Storm - Liouville has been investigated; The spectroscopic information for proton halo in 8 B and values of the magnetic dipole and electric quadrupole moments of 8 B and 8 Li with use of technique of genealogical coefficients have been obtained. The contribution of 2p - shell of 13 C (α, n) 16 O reaction has been estimated. (author)
Long-lived high-spin isomers in the neutron-deficient 1g sub(9/2)-shell nuclei
International Nuclear Information System (INIS)
Ogawa, K.
1981-09-01
The neutron-deficient 1g sub(9/2)-shell nuclei are studied in the framework of the shell model with active nucleons occuping the 1g sub(9/2) and 2p sub(1/2) shells. The calculated result for 95 Pd shows good agreement with the recent experiment by Nolte and Hick. Many ''spin-gap'' Isomers are predicted in the region of A = 76 -- 84 and A = 95 -- 100. (author)
Nuclear structure of the N = Z odd - odd nuclei around N=28 closed shell interpreted with IBFFM
International Nuclear Information System (INIS)
Dragulescu, E.; Serbanut, G. C.; Serbanut, I.
2001-01-01
In the very recent years the knowledge of the level structure at lower and higher energies in the fpg shell N=Z nuclei has renewed a growing interest due to major improvements in the theoretical techniques. Going away from closed shell, the shell model calculations rapidly exhaust computer capabilities and we must resort to the model observed on collective phenomena. The fpg odd-odd N = Z nuclei close to the doubly magic 56 Ni nucleus are good candidates to investigate the competition between collective and single-particle excitations. Here part of the results obtained from an exhaustive systematic study of the self conjugate doubly-odd nuclei with A > 62: 62 Ga and 66 As nuclei using the interacting - boson - fermion - fermion - model (IBFFM) is presented. The odd-odd nuclei are described in the framework of the IBFFM by coupling valence shell proton and neutron quasiparticles to even-even core described in the interacting - boson model. In the first step of the calculations the core parameters for 60 Zn and 64 Ge cores were fitted to the energies of their excited states. In the second step of calculations, we have adjusted the IBFM proton Hamiltonian to the low - lying levels of 63 Ga and 67 As nuclei and IBFM neutron Hamiltonian of low - lying levels of 61 Zn and 65 Ge nuclei involved in the cases of the structure of odd-odd 62 Ga and 66 As nuclei. We have finally calculated the level spectra and electromagnetic properties of above mentioned nuclei. The IBFFM positive - parity energy spectra are compared with experimental ones. The calculations show a reasonable agreement with experimental data and existing shell - model calculations. (authors)
A novel approach to the systematization of α-decaying nuclei, based on shell structures
International Nuclear Information System (INIS)
Yarman, Tolga; Azmi Altintas, Ali; Zaim, Nimet; Amon Susam, Lidya; Kholmetskii, Alexander; Arik, Metin; Ozaydin, Fatih
2016-01-01
We provide a novel systematization of α-decaying nuclei, starting with the classically adopted mechanism. The decay half-life of an α-disintegrating nucleus is framed, supposing that i) the α-particle is born inside the parent, then ii) it keeps on hitting the barrier, while it runs back and forth inside the parent, and hitting each time the barrier, and iii) it finally tunnels through the barrier. One can, knowing the decay half-life, consider the probability that the α-particle is born within the parent, before it is emitted, as a parameter. Under all circumstances, the decay appears to be governed by the shell structure of the given nucleus. Our approach well allows to incorporate (not only even-even nuclei, but) all nuclei, decaying via throwing an alpha particle. Though herein, we limit ourselves with just even-even nuclei, in the aim of comparing our results with the existing Geiger-Nuttal results. (orig.)
Two-body and three-body correlations in Os-shell nuclei
International Nuclear Information System (INIS)
Halderson, D.W.
1974-01-01
It is well known that conventional Brueckner calculations with modern nucleon-nucleon potentials have failed to reproduce experimental saturation properties of finite nuclei. The intent was to determine whether the discrepancies are due to the methods of calculation or the nucleon-nucleon potentials. Brueckner procedures which include only two-body correlations were applied to Os-shell nuclei. Calculations were performed with and without the Hartree-Fock condition, with and without partial occupation probabilities, and with various propagators and Pauli correction techniques. Then the entire class of three-body correlations was calculated by matrix solution of the Bethe-Faddeev equations. The convergence necessary to validate this technique was achieved by constructing a set of basic functions which contain no center of mass excitations and yet are still properly antisymmetrized. The two-body calculations yielded typical Brueckner results. The nuclei were underbound or the radii were too small. However, the three-body calculations yielded reasonable radii and moderate overbinding for the Reid soft core and Hamada-Johnston potentials. Therefore, the Bethe-Faddeev formalism has been shown to be a reasonable approach to calculation of the three-body correlations in finite nuclei; and the results of []these calculations demonstrate that the underbinding and collapsed radii of two-body calculations were largely due to the uncalculated correlations. (auth)
Study of transfer reactions (α,t), (α,3He) in the f-p shell: mechanism and spectroscopic use
International Nuclear Information System (INIS)
Roussel, P.
1968-05-01
We describe an experimental study of (α,t), (α, 3 He) reactions at 44 MeV using a solid-state identifier, on the target-nuclei 54 Fe and 58,60,62,64 Ni. A critical study of optical model and of disturbed wave analysis has been performed. We show the complementarity of different transfer-reactions, the ambiguity of spectroscopic factors, the importance of the problem of the reaction mechanism. (author) [fr
Origin of fine structure of the giant dipole resonance in s d -shell nuclei
Fearick, R. W.; Erler, B.; Matsubara, H.; von Neumann-Cosel, P.; Richter, A.; Roth, R.; Tamii, A.
2018-04-01
A set of high-resolution zero-degree inelastic proton scattering data on 24Mg, 28Si, 32S, and 40Ca provides new insight into the long-standing puzzle of the origin of fragmentation of the giant dipole resonance (GDR) in s d -shell nuclei. Understanding is achieved by comparison with random phase approximation calculations for deformed nuclei using for the first time a realistic nucleon-nucleon interaction derived from the Argonne V18 potential with the unitary correlation operator method and supplemented by a phenomenological three-nucleon contact interaction. A wavelet analysis allows one to extract significant scales both in the data and calculations characterizing the fine structure of the GDR. The fair agreement for scales in the range of a few hundred keV supports the surmise that the fine structure arises from ground-state deformation driven by α clustering.
Projected shell model study of odd-odd f-p-g shell proton-rich nuclei
International Nuclear Information System (INIS)
Palit, R.; Sheikh, J.A.; Sun, Y.; Jain, H.C.
2003-01-01
A systematic study of two-quasiparticle bands of the proton-rich odd-odd nuclei in the mass A∼70-80 region is performed using the projected shell model approach. The study includes Br, Rb, and Y isotopes with N=Z+2 and Z+4. We describe the energy spectra and electromagnetic transition strengths in terms of the configuration mixing of the angular-momentum projected multi-quasiparticle states. Signature splitting and signature inversion in the rotational bands are discussed and are shown to be well described. A preliminary study of the odd-odd N=Z nucleus 74 Rb, using the concept of spontaneous symmetry breaking is also presented
Microscopic boson approach to the description of sd-shell nuclei
International Nuclear Information System (INIS)
Kuchta, R.
1987-01-01
A microscopic method is proposed for analyzing the properties of light nuclei with an equal number of protons and neutrons in terms of many interacting bosons. An exact boson image of the underlying shell-model Hamiltonian is derived and the dynamical behaviour of the original fermion system is studied directly in the boson picture using the mean field approximation. The resulting boson states are shown to be free from spurios components, so that the cubersome procedure of constructing the physical boson states can be avoided. The method is applied to calculating the energy spectra of 20 Ne, 24 Mg and a satisfactory agreement with experimental data is found
Realistic Gamow shell model for resonance and continuum in atomic nuclei
Xu, F. R.; Sun, Z. H.; Wu, Q.; Hu, B. S.; Dai, S. J.
2018-02-01
The Gamow shell model can describe resonance and continuum for atomic nuclei. The model is established in the complex-moment (complex-k) plane of the Berggren coordinates in which bound, resonant and continuum states are treated on equal footing self-consistently. In the present work, the realistic nuclear force, CD Bonn, has been used. We have developed the full \\hat{Q}-box folded-diagram method to derive the realistic effective interaction in the model space which is nondegenerate and contains resonance and continuum channels. The CD-Bonn potential is renormalized using the V low-k method. With choosing 16O as the inert core, we have applied the Gamow shell model to oxygen isotopes.
Microscopic studies of electric dipole resonances in 1p shell nuclei
International Nuclear Information System (INIS)
Kissener, H.R.; Rotter, I.; Goncharova, N.G.
1986-05-01
Recent data on total and partial photonuclear cross sections in the GDR region of the nuclei 6 Li to 16 O are compared with theoretical predictions, mostly from shell model and continuum shell model studies. The influence of the size of the configuration space, of the adopted residual interaction and of the continuous spectrum on the isovector E1 response is discussed to some detail. The observed trends of the localization, the shape and width, the isospin and the configurational structure of the GDR with increasing 1p shell occupation are related to the microscopic structure of the nuclear ground state. Particular attention is given to the partial (γ, N/sub i/) disintegration channels. Complex-particle emission and isospin mixing in the nuclear states are discussed for a few cases. An attempt is made to bring some systematics also in the evidence on excited-state giant resonances through the 1p shell region. The photonuclear GDR is compared with other giant multipole excitations, mostly for the example of the 14 C nucleus. (author)
Zeng, Shao-Ju; Xi, Chao; Zhang, Xin-Wen; Zuo, Ming-Xue
2007-01-01
There is a clear core-versus-shell distinction in cytoarchitecture, electrophysiological properties and neural connections in the mesencephalic and diencephalic auditory nuclei of amniotes. Determining whether the embryogenesis of auditory nuclei shows a similar organization is helpful for further understanding the constituent organization and evolution of auditory nuclei. Therefore in the present study, we injected [(3)H]-thymidine into turtle embryos (Pelodiscus sinensis) at various stages of development. Upon hatching, [(3)H]-thymidine labeling was examined in both the core and shell auditory regions in the midbrain, diencephalon and dorsal ventricular ridge. Met-enkephalin and substance P immunohistochemistry was used to distinguish the core and shell regions. In the mesencephalic auditory nucleus, the occurrence of heavily labeled neurons in the nucleus centralis of the torus semicircularis reached its peak at embryonic day 9, one day later than the surrounding shell. In the diencephalic auditory nucleus, the production of heavily labeled neurons in the central region of the reuniens (Re) was highest at embryonic day (E) 8, one day later than that in the shell region of reuniens. In the region of the dorsal ventricular ridge that received inputs from the central region of Re, the appearance of heavily labeled neurons also reached a peak one day later than that in the area receiving inputs from the shell region of reuniens. Thus, there is a core-versus-shell organization of neuronal generation in reptilian auditory areas. Copyright (c) 2007 S. Karger AG, Basel.
Energy Technology Data Exchange (ETDEWEB)
Kremer, Christoph
2016-01-27
The first part of this thesis revolves around symmetries in the sd-IBA-1. A region of approximate O(6) symmetry for the ground-state band, a partial dynamical symmetry (PDS) of type III, in the parameter space of the extended consistent-Q formalism is identified through quantum number fluctuations. The simultaneous occurrence of a SU(3) quasi dynamical symmetry for nuclei in the region of O(6) PDS is explained via the β=1, γ=0 intrinsic state underlying the ground-state band. The previously unrelated concepts of PDS and QDS are connected for the first time and many nuclei in the rare earth region that approximately satisfy both symmetry requirements are identified. Ground-state to ground-state (p, t) transfer reactions are presented as an experimental signature to identify pairs of nuclei that both exhibit O(6) PDS. In the second part of this thesis inelastic electron scattering off {sup 96}Zr is studied. The experiment was performed at the high resolution Lintott spectrometer at the S-DALINAC and covered a momentum-transfer range of 0.28 - 0.59 fm{sup -1}. Through a relative analysis using Plane Wave Born Approximation (PWBA) the B(E2;2{sup +}{sub 2}→0{sup +}{sub 1}) value is extracted without incurring the additional model dependence of a Distorted Wave Born Approximation (DWBA). By combining this result with known multipole mixing ratios and branching ratios all decay strengths of the 2{sup +}{sub 2} state are determined. A mixing calculation establishes very weak mixing (V{sub mix}=76 keV) between states of the ground-state band and those of the band build on top of the 0{sup +}{sub 2} state which includes the 2{sup +}{sub 2} state. The occurrence of these two isolated bands is interpreted within the shell model in terms of type II shell evolution.
Rodríguez-Guzmán, R.; Robledo, L. M.; Sharma, M. M.
2015-06-01
The quadrupole collectivity in Nd, Sm, Gd, Dy, Er, Yb, Hf and W nuclei with neutron numbers 122 ≤ N ≤ 156 is studied, both at the mean field level and beyond, using the Gogny energy density functional. Besides the robustness of the N = 126 neutron shell closure, it is shown that the onset of static deformations in those isotopic chains with increasing neutron number leads to an enhanced stability and further extends the corresponding two-neutron drip lines far beyond what could be expected from spherical calculations. Independence of the mean-field predictions with respect to the particular version of the Gogny energy density functional employed is demonstrated by comparing results based on the D1S and D1M parameter sets. Correlations beyond mean field are taken into account in the framework of the angular momentum projected generator coordinate method calculation. It is shown that N = 126 remains a robust neutron magic number when dynamical effects are included. The analysis of the collective wave functions, average deformations and excitation energies indicate that, with increasing neutron number, the zero-point quantum corrections lead to dominant prolate configurations in the 0{1/+}, 0{2/+}, 2{1/+} and 2{2/+} states of the studied nuclei. Moreover, those dynamical deformation effects provide an enhanced stability that further supports the mean-field predictions, corroborating a shift of the r-process path to higher neutron numbers. Beyond mean-field calculations provide a smaller shell gap at N = 126 than the mean-field one in good agreement with previous theoretical studies. However, the shell gap still remains strong enough in the two-neutron drip lines.
The 1(h/2π)ω spectra of nuclei with a nearly half-filled 1p shell
International Nuclear Information System (INIS)
Jaeger, H.U.; Kirchbach, M.
1977-01-01
The effective particle-hole interaction of Millener and Kurath which contains non-central components is used to study the non-normal parity states of A = 9 - 12 nuclei in the framework of all non-spurious 1(h/2π)ω excitations. Additional calculations with a pure central force confirm the conclusion that non-central forces are necessary for a unified description of non-normal parity states in 1p-shell nuclei. (author)
Ab initio results for intermediate-mass, open-shell nuclei
Baker, Robert B.; Dytrych, Tomas; Launey, Kristina D.; Draayer, Jerry P.
2017-01-01
A theoretical understanding of nuclei in the intermediate-mass region is vital to astrophysical models, especially for nucleosynthesis. Here, we employ the ab initio symmetry-adapted no-core shell model (SA-NCSM) in an effort to push first-principle calculations across the sd-shell region. The ab initio SA-NCSM's advantages come from its ability to control the growth of model spaces by including only physically relevant subspaces, which allows us to explore ultra-large model spaces beyond the reach of other methods. We report on calculations for 19Ne and 20Ne up through 13 harmonic oscillator shells using realistic interactions and discuss the underlying structure as well as implications for various astrophysical reactions. This work was supported by the U.S. NSF (OCI-0904874 and ACI -1516338) and the U.S. DOE (DE-SC0005248), and also benefitted from the Blue Waters sustained-petascale computing project and high performance computing resources provided by LSU.
The effect of quadrupole force to the spectra of nuclei in the f7/2 shell
International Nuclear Information System (INIS)
Zhang Qingying
1992-01-01
The effect of quadrupole force on the spectra of nuclei in the f 7/2 shell is tested. The nuclear spectra are calculated by using the surface delta interaction plus quadrupole interaction and the modified surface delta interaction respectively. The results calculated with the former are much better than those with the latter, the role of the isospin modified term in the modified surface delta interaction can be substituted by the quadrupole interaction term. It is also shown that the effect of quadrupole interaction in the f 7/2 shell is important although the quadrupole deformations of nuclei in this region are not large
Pairing correlations in N ∝Z pf-shell nuclei
International Nuclear Information System (INIS)
Langanke, K.; Dean, D.J.; Koonin, S.E.; Radha, P.B.
1997-01-01
We perform shell model Monte Carlo calculations to study pair correlations in the ground states of N=Z nuclei with masses A=48-60. We find that T=1, J π =0 + proton-neutron correlations play an important, and even dominant role, in the ground states of odd-odd N=Z nuclei, in agreement with experiment. By studying pairing in the ground states of 52-58 Fe, we observe that the isovector proton-neutron correlations decrease rapidly with increasing neutron excess. In contrast, both the proton, and trivially the neutron correlations increase as neutrons are added. We also study the thermal properties and the temperature dependence of pair correlations for 50 Mn and 52 Fe as exemplars of odd-odd and even-even N=Z nuclei. While for 52 Fe results are similar to those obtained for other even-even nuclei in this mass range, the properties of 50 Mn at low temperatures are strongly influenced by isovector neutron-proton pairing. In coexistence with these isovector pair correlations, our calculations also indicate an excess of isoscalar proton-neutron pairing over the mean-field values. The isovector neutron-proton correlations rapidly decrease with temperatures and vanish for temperatures above T=700 keV, while the isovector correlations among like-nucleons persist to higher temperatures. Related to the quenching of the isovector proton-neutron correlations, the average isospin decreases from 1, appropriate for the ground state, to 0 as the temperature increases. (orig.)
Microscopic theory of light exotic nuclei. Shell Models Embedded in the Continuum
International Nuclear Information System (INIS)
Bennaceur, K.
1999-01-01
The recent advances in experimental nuclear physics make it possible to study nuclear systems far from the beta stability line. The discovery of new phenomena, like halos or neutron skins, requires the development of new theoretical models which enable to study these systems. The first part of this work is devoted to the development and the applications of the Shell Model Embedded in the Continuum (SMEC). This new formalism allows to take into account the correlations between the bound and scattering states of loosely bound nuclei. SMEC is applied here to the study of the spectroscopy of the Mirror nuclei 8 B- 8 Li and 17 F- 17 O. It can also be used to calculate the cross sections of the elastic scattering, the Coulomb breakup processes and the radiative n,p capture processes. The results concerning the reactions of astrophysical interest: 18 O(p, γ) 17 F and 7 Be(p, γ) 8 B, are discussed in details. This last reaction is very important because the disintegration of 8 B is the main source of High energy neutrinos in the sun. The second part of this work is related to the analysis of pairing interaction for weakly bound nuclei. We have developed a new approach, based on the Hartree-Fock-Bogolyubov (HFB) theory, that allows to study the pairing correlations between bound and scattering states, both resonant and not resonant ones. The 'particle-hole' potential is replaced by a model potential for which the solutions are analytically known. This method allows to analyse the effect of pairing on bound and resonant states, independently of their energy position. We have clearly demonstrated that the non-resonant continuum plays a crucial role in the loosely bound nuclei and that solving the HFB equations in the coordinate space is the only method that permits to treat this problem correctly. (author)
International Nuclear Information System (INIS)
Flocard, H.
1975-04-01
Hartree-Fock results concerning the ground state properties of some S-D shell nuclei are discussed. Two different Skyrme interactions have been used. They both lead to good agreement with the experimental total binding energies, charge radii and multipole moments. In particular the observed prolate-oblate transitions occuring in the S-D shell are reproduced. The calculated spectroscopic factors are also shown to be consistent with experimental data [fr
Study of the (p,α)-reaction on sd-shell nuclei and their microscopic analysis
International Nuclear Information System (INIS)
Hoyler, F.
1982-01-01
In the present thesis the (p,α) reaction on the 2s-1d-shell nuclei 23 Na, 24 Mg, 26 Mg, 27 Al, 35 Cl, 37 Cl, and 39 K was measured. The experiments were performed at the isochronous cyclotron JULIC of the Institute for Nuclear Physics of the Nuclear Research Facility Juelich and at the Emperor Van-de-Graaff accelerator of the Max Planck Institute for Nuclear Physics Heidelberg. Angular distributions for transitions to several residual nucleus states were evaluated in the energy range between 18 and 45 MeV incident proton energy. By the application of magnetic spectrometers as detection device an energy resolution between 25 and 45 keV could be reached. (orig./HSI) [de
Excitation of the giant resonance in the radiative pion capture on lp shell nuclei
International Nuclear Information System (INIS)
Dogotar', G.E.
1978-01-01
The spin-dipole transitions in the (π - ,γ) reaction on 6 Li, 7 Li, 9 Be, 13 C and 14 N are calculated in the framework of shell model and are compared with experiment. The discussion includes the gross structure and the quantum numbers of the resonance, relative branchings, prominent partial transitions and total yields. General findings is that the calculated (π - ,γ) yield distributions describe the data well in those cases where also the photonuclear data are well reproduced, although the amplitudes of the elementary processes are different. In the case considered, the best agreement is obtained for A=9 and 14. The configurational splitting of the resonances is clearly seen in the A=6 and 7 cases, to somewhat less extent also for A=9. For heavier nuclei the contribution from hole excitation is small and is spread out. For A=7 and 11 the calculated main peaks are at too low intrinsic excitation energies as compared with histograms
Quasi-SU(3) truncation scheme for even-even sd-shell nuclei
International Nuclear Information System (INIS)
Vargas, C.E.; Hirsch, J.G.; Draayer, J.P.
2001-01-01
The quasi-SU(3) symmetry was uncovered in full pf and sdg shell-model calculations for both even-even and odd-even nuclei. It manifests itself through a dominance of single-particle and quadrupole-quadrupole terms in a Hamiltonian used to describe well-deformed nuclei. A practical consequence of the quasi-SU(3) symmetry is an efficient basis truncation scheme. In [C.E. Vargas et al., Phys. Rev. C 58 (1998) 1488] it is shown that when this type of Hamiltonian is diagonalized in an SU(3) basis, only a few irreducible representations (irreps) of SU(3) are needed to describe the yrast band, the leading S=0 irrep augmented with the leading S=1 irreps in the proton and neutron subspaces. In the present article the quasi-SU(3) truncation scheme is used, in conjunction with a 'realistic but schematic' Hamiltonian that includes the most important multipole terms, to describe the energy spectra and B(E2) transition strengths of 20,22 Ne, 24 Mg and 28 Si. The effect of the size of the Hilbert space on both sets of observables is discussed, as well as the structure of the yrast band and the importance of the various terms in the Hamiltonian. The limitations of the model are explicitly discussed
Quasi-SU(3) truncation scheme for even-even sd-shell nuclei
Energy Technology Data Exchange (ETDEWEB)
Vargas, C.E. E-mail: cvargas@fis.cinvestav.mx; Hirsch, J.G. E-mail: hirsch@nuclecu.unam.mx; Draayer, J.P. E-mail: draayer@lsu.edu
2001-07-30
The quasi-SU(3) symmetry was uncovered in full pf and sdg shell-model calculations for both even-even and odd-even nuclei. It manifests itself through a dominance of single-particle and quadrupole-quadrupole terms in a Hamiltonian used to describe well-deformed nuclei. A practical consequence of the quasi-SU(3) symmetry is an efficient basis truncation scheme. In [C.E. Vargas et al., Phys. Rev. C 58 (1998) 1488] it is shown that when this type of Hamiltonian is diagonalized in an SU(3) basis, only a few irreducible representations (irreps) of SU(3) are needed to describe the yrast band, the leading S=0 irrep augmented with the leading S=1 irreps in the proton and neutron subspaces. In the present article the quasi-SU(3) truncation scheme is used, in conjunction with a 'realistic but schematic' Hamiltonian that includes the most important multipole terms, to describe the energy spectra and B(E2) transition strengths of {sup 20,22}Ne, {sup 24}Mg and {sup 28}Si. The effect of the size of the Hilbert space on both sets of observables is discussed, as well as the structure of the yrast band and the importance of the various terms in the Hamiltonian. The limitations of the model are explicitly discussed.
Approximate symmetries in atomic nuclei from a large-scale shell-model perspective
Launey, K. D.; Draayer, J. P.; Dytrych, T.; Sun, G.-H.; Dong, S.-H.
2015-05-01
In this paper, we review recent developments that aim to achieve further understanding of the structure of atomic nuclei, by capitalizing on exact symmetries as well as approximate symmetries found to dominate low-lying nuclear states. The findings confirm the essential role played by the Sp(3, ℝ) symplectic symmetry to inform the interaction and the relevant model spaces in nuclear modeling. The significance of the Sp(3, ℝ) symmetry for a description of a quantum system of strongly interacting particles naturally emerges from the physical relevance of its generators, which directly relate to particle momentum and position coordinates, and represent important observables, such as, the many-particle kinetic energy, the monopole operator, the quadrupole moment and the angular momentum. We show that it is imperative that shell-model spaces be expanded well beyond the current limits to accommodate particle excitations that appear critical to enhanced collectivity in heavier systems and to highly-deformed spatial structures, exemplified by the second 0+ state in 12C (the challenging Hoyle state) and 8Be. While such states are presently inaccessible by large-scale no-core shell models, symmetry-based considerations are found to be essential.
Application of shell model with the modified surface delta interaction to 42Ca and 42Sc nuclei
International Nuclear Information System (INIS)
Jasielska, A.; Wiktor, S.
1975-01-01
The shell model with MSDI residual interaction is used to investigate properties of levels in the 42 Ca and 42 Sc nuclei. The 40 Ca core with two active outer nucleons is assumed. The energy matrices are diagonalized and the calculated level schemes for both 42 Ca and 42 Sc nuclei are presented. In both nuclei the density of the calculated levels is significantly less than of the observed levels. This fact leads to the conclusion, that some core excitation modes play an important role in the formation of low-lying states in the 42 Ca and 42 Sc nuclei. The calculated eigenvalues and eigenvectors of the states below 5 MeV are given. (author)
International Nuclear Information System (INIS)
Sagajdak, R.N.
2008-01-01
The production of heavy nuclei from Rn to Th around the N = 126 neutron shell in complete fusion reactions of nuclei has been considered in a systematic way in the framework of the conventional barrier-passing fusion model coupled with the Standard Statistical Model (SSM). Available data on the excitation functions for fusion and production of evaporation residues obtained in very asymmetric combinations are described with these models rather well. In the interaction of massive projectiles with heavy target nuclei quasi-fission effects appear in the entrance reaction channel. The quantity of the fusion probability introduced empirically has been used to reproduce excitation functions with the same SSM parameters (fission barriers) as those obtained in the analysis of very asymmetric combinations. A lack of stabilization against fission around N = 126 for Th nuclei was earlier explained with a reduced collective contribution to the level density in spherical nuclei. However, the present analysis shows severe inhibition for fusion, i.e., the drop in production cross sections of Th nuclei in the vicinity of N = 126 is mainly caused by entrance channel effects. The macroscopic component of fission barriers for nuclei involved in a deexcitation cascade has been derived and compared with the theoretical model predictions and available data
International Nuclear Information System (INIS)
Dupuis, M.; Karataglidis, S.; Bauge, E.; Delaroche, J.P.; Gogny, D.
2006-01-01
The random phase approximation (RPA) long-range correlations are known to play a significant role in understanding the depletion of single particle-hole states observed in (e,e ' ) and (e,e ' p) measurements. Here the RPA theory, implemented using the D1S force is considered for the specific purpose of building correlated ground states and related one-body density matrix elements. These may be implemented and tested in a fully microscopic optical model for NA scattering off doubly closed-shell nuclei. A method is presented to correct for the correlations overcounting inherent to the RPA formalism. One-body density matrix elements in the uncorrelated (i.e., Hartree-Fock) and correlated (i.e., RPA) ground states are then challenged in proton scattering studies based on the Melbourne microscopic optical model to highlight the role played by the RPA correlations. Agreement between the parameter free scattering predictions and measurements is good for incident proton energies ranging from 200 MeV down to approximately 60 MeV and becomes gradually worse in the lower energy range. Those features point unambiguously to the relevance of the g-matrix method to build microscopic optical model potentials at medium energies, and emphasize the need to include nucleon-phonon coupling, that is, a second-order component of the Feshbach type in the potential at lower energies. Illustrations are given for proton scattering observables measured up to 201 MeV for the 16 O, 40 Ca, 48 Ca, and 208 Pb target nuclei
Nuclear shell effects in neutron-rich nuclei around N=20 and N=32,34
Seidlitz, M
Nuclear shell effects in neutron-rich nuclei around N=20 and N=32,34 were studied by means of reduced transition probabilities, i.e. B(E2) and B(M1) values. To this end a series of Coulomb-excitation experiments, employing radioactive 31Mg and 29,30Na beams, as well as a precise lifetime experiment of excited states in 56Cr were performed. The collective properties of excited states of 31Mg were the subject of a Coulomb-excitation experiment at REX-ISOLDE, CERN, employing a radioactive 31Mg beam at a beam energy of 3.0 MeV/u. The beam intensity amounted to 3000 ions/s on average. The highly efficient MINIBALL setup was employed, consisting of eight HPGe cluster detectors for gamma-ray detection and a segmented Si-detector for coincident particle detection. The level scheme of 31Mg was extended. Spin and parity assignment of the observed 945 keV state yielded 5/2+ and its de-excitation is dominated by a strong collective M1 transition. Comparison of the transition probabilities of 30,31,32Mg establishes that f...
Spectroscopy of 96-98Ru and neighboring nuclei: shell model calculations and lifetime measurements
International Nuclear Information System (INIS)
Kharraja, B.; Garg, U.; Ghugre, S.S.
1997-01-01
High Spin states in 94,95 Mo, 94-96 Tc, 96-98 Ru and 97,98 Rh were populated via the 65 Cu( 36 S,xpyn) reactions at 142 MeV. Level schemes of these nuclei have been extended up to a spin of J ∼ 20ℎ and an excitation energy of E x ∼12 -14 MeV. Information on the high spin structure for 96 Tc and 98 Rh has been obtained for the first time. Spherical shell model calculations have been performed and compared with the experimental excitation energies. The level structures of the N=51, 52 isotones exhibit single-particle nature even at the highest spins and excitation energies. A fragmentation of intensity into several branches after breaking of the N = 50 core has been observed. There are indications for the onset of collectivity around neutron number N = 53 in this mass region. A sequence of E2 transitions, reminiscent of vibrational degree of freedom, were observed in 98 Ru at spins just above the observed N = 50 core breaking. RDM lifetime measurements have been performed to ascertain the intrinsic structures of these level sequences. (author)
Nuclear shell effects in neutron-rich nuclei around N=20 and N=32,34
International Nuclear Information System (INIS)
Seidlitz, Michael
2012-01-01
Nuclear shell effects in neutron-rich nuclei around N=20 and N=32,34 were studied by means of reduced transition probabilities, i.e. B(E2) and B(M1) values. To this end a series of Coulomb-excitation experiments, employing radioactive 31 Mg and 29,30 Na beams, as well as a precise lifetime experiment of excited states in 56 Cr were performed. The collective properties of excited states of 31 Mg were the subject of a Coulomb-excitation experiment at REX-ISOLDE, CERN, employing a radioactive 31 Mg beam at a beam energy of 3.0 MeV/u. The beam intensity amounted to 3000 ions/s on average. The highly efficient MINIBALL setup was employed, consisting of eight HPGe cluster detectors for γ-ray detection and a segmented Si-detector for coincident particle detection. The level scheme of 31 Mg was extended. Spin and parity assignment of the observed 945 keV state yielded 5/2 + and its de-excitation is dominated by a strong collective M1 transition. Comparison of the transition probabilities of 30,31,32 Mg establishes that for the N=19 magnesium isotope not only the ground state but also excited states are largely dominated by a deformed pf intruder configuration. This implies that 31 Mg is part of the so-called ''island of inversion''. Coulomb-excitation experiments of radioactive 29,30 Na were carried out at REX-ISOLDE, CERN, at a final beam energy of 2.85 MeV/u. De-excitation γ rays were detected by the MINIBALL γ-ray spectrometer in coincidence with scattered particles in a segmented Si-detector. Despite rather low beam intensities transition probabilities to the first excited states were deduced. Results of very recently published experiments at MSU and TRIUMF could be largely confirmed and extended. The measured B(E2) values agree well with shell-model predictions, supporting the idea that in the sodium isotopic chain the ground-state wave function contains a significant intruder admixture already at N=18, with N=19 having an almost pure 2p2h deformed ground
International Nuclear Information System (INIS)
Sagaidak, R. N.
2009-01-01
Nuclear fission is well suited to study the dynamic properties and dissipative processes in cold and moderately excited nuclei. It is also a unique tool to explore level density and shell effects at an extreme deformation. Despite the significant progress in the fission studies, the isospin dependence of fission properties and, in particular, of fission barrier heights still remains an open problem. Theoretical fission model parameters are tuned by using the experimental nuclear and fission data close to stability [1]. The models provide a reasonable description of the fission barriers close to the stability line. However, large deviations are observed between predictions of different models for the fission barriers of very neutron-deficient and neutron-rich nuclei. These discrepancies (by as much as 20-30 MeV, see, e.g. [2]) become especially important in the r-process calculations for extremely neutron-rich nuclei, whose fission barriers determine the termination of the r-process by fission [3]. Unfortunately, such neutron-rich nuclei will probably not become accessible in the nearest experiments. Therefore, fission properties of exotic nuclei and especially their isospin dependence can be investigated in alternative regions of the Nuclide Chart, which are accessible for such studies now. Fusion-evaporation cross sections for heavy fissile nuclei obtained in heavy ion induced reactions as well as their fission cross sections are mainly determined by statistical properties of decaying compound nuclei (CN) and first of all by the fission-barrier heights of nuclei involved in the de-excitation chains leading to observable evaporation residues (ER). At the same time, the ER production and fission in nearly symmetric projectile-target fusion reactions leading to the most neutron-deficient CN could be strongly suppressed due to the quasi-fission (QF) effect [4], as observed recently in the 4 8C a induced reactions leading to Ra [5] and Pb [6] CN. The production of
International Nuclear Information System (INIS)
Gillet, V.; Giraud, B.; Rho, M.
1976-01-01
The energy levels and transition properties of the even-even N=28, 50 isotones and Z=28, 50, 82 isotopes are calculated in the framework of the Tamm-Dancoff and Random Phase Approximation, with an effective central interaction in an extended space consisting of two quasi-particle configurations for the open shell and particle-hole configurations for the closed core. Using the results of the Inverse Gap Equation Method, practically all the necessary input data (single quasi-particle energies, force strength) are extracted from the odd-mass nuclei. The ratios of the force components are kept at fixed values for all studied nuclei and no effective charge is used. An overall excellent agreement is obtained for the energies of the vibrational states. On the other hand, while the transition properties of the 3 - states are always well reproduced, those of the 2 + and 4 + states are often too small by about one order of magnitude [fr
Alpha-cluster transfer process in colliding S-D shell nuclei using the energy density formalism
International Nuclear Information System (INIS)
Puri, R.K.; Gupta, R.K.
1992-01-01
The energy density formalism is used for the first time to study the resonance-like behaviour of the α-cluster transfer process, observed for collisions between the s-d shell nuclei. Within the dynamical fragmentation theory, this formalism is shown to give better the observed alpha resonance-like mass spectrum of colliding α-particle nuclei and its suppression on adding neutrons to either of the α-particle reaction partners, compared with the earlier calculations of one of us and collaborators using the proximity pocket formula. For composite systems with N>>Z, these calculations predict an explicit preference for transfer of those clusters that are observed in recent cluster radioactivity. (Author)
On the nature of some monopole resonances of p-shell nuclei
International Nuclear Information System (INIS)
Filippov, G.F.; Vasilevsky, V.S.; Nesterov, A.V.
1982-01-01
The resonance structure of states of a continuous spectrum of light nuclei is studied. Using 7 Li and 8 Be as an example it is shown that in these nuclei there exist a near-threshold resonance the share of which is about 50-70 % of isoscalar monopole sum rule. The experimental method of finding the near-threshold resonances is described
Investigations of collective and single-particle aspects of excitation in 1fsub(7/2) shell nuclei
International Nuclear Information System (INIS)
Styczen, J.
1976-01-01
Experimental data are presented which were obtained in spectroscopic studies on 1fsub(7/2) shell nuclei in the following reactions: 30 Si( 16 0,pn) 44 Sc, 44 Ca(p,n) 44 Sc, 42 Ca(α,p) 45 Sc, 42 Ca(α,n) 45 Sc, 45 Sc(α,pn) 47 Ti, 46 Ti(α,p) 49 V, 47 Ti(α,pn) 49 V, and 49 Ti(p,n) 49 V. Experimental reduced transition probabilities B(M1) and B(E2) have been systematically compared for inband transitions of Ksup(π)=3/2 + bands in sup(43,45,47)Sc, 45 Ti and sup(47,49)V nuclei. In the framework of the pure rotational model, intrinsic quadrupole moments |Qsub(o)| and |gsub(K)-gsub(R)| ratios have been derived. Band mixing calculations in a strong coupling model treating more correctly the j 2 term in the hamiltonian and hole excitations, have been indertaken on properties of negativeparity states in the cross-conjugate nuclei 47 Ti- 49 V and V 47 - 49 Dr. There is an overall good agreement between the experimental data and the theoretical predictions. The strong coupling model has been also used to study possible regions of stable deformation for the positive parity states of the odd nuclei in the 1fsub(7/2) shell. Band mixing calculations performed for these states have shown that the experimental data are well reproduced in the calculations with a deformation parameter corresponding to a minimum of the static potential energy. (author)
International Nuclear Information System (INIS)
Piecuch, Piotr; Wloch, Marta; Gour, Jeffrey R.; Dean, David J.; Papenbrock, Thomas; Hjorth-Jensen, Morten
2005-01-01
We review basic elements of the single-reference coupled-cluster theory and discuss large scale ab initio calculations of ground and excited states of 15O, 16O, and 17O 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 obtain the converged results for 16O and promising preliminary results for 15O and 17O at the level of two-body interactions. The calculated properties other than energies include matter density, 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 7 or 8 major oscillator shells, for which non-truncated shell-model calculations for nuclei with A = 15 17 active particles are presently not possible. We argue that the use of coupled-cluster methods and computer algorithms developed by quantum chemists to calculate properties of nuclei is an important step toward the development of accurate and affordable many-body theories that cross the boundaries of various physical sciences
Magnetic dipole moments of deformed odd-odd nuclei up to 2p-1f shells
Energy Technology Data Exchange (ETDEWEB)
Garg, V P; Verma, A K; Gandhi, R; Sharma, S D [Punjabi Univ., Patiala (India). Dept. of Physics
1981-02-01
The expression for magnetic moments for the states comprising ground state configurations of odd-odd nuclei has been simplified by excluding mixing of other nucleonic configurations. This is contrary to Sharma's and Davidson's results which had been obtained by diagonalizing state matrices for a set of parameters using Davidov and Filippov's non-axial rotor model. According to the relative directions of spins of unpaired odd nucleons, the nuclei have been classified under four categories-an exercise not attempted till now. The calculations have been done with various quenching factors depending upon the relative spin orientations of odd nucleons. For most of the nuclei, the results show considerable improvement over those of Gallagher and Moszkowski and of Sharma.
International Nuclear Information System (INIS)
Hoffmann, B.
1984-07-01
In three chapters different physical situations are described which have commonly the Coulomb interaction as driving force. The first two chapters study the Coulomb interactions in connection with the excitation of inner electron shells and the Coulomb excitation of nuclei in first order. In the third part on effect ofthe Coulomb interaction between electronic shell and nucleus is treated in second order (nuclear polarization), and its effect on the isotopic and isomeric shift is studied. (orig./HSI) [de
Development of the α-decay theory of spherical nuclei by means of the shell model
International Nuclear Information System (INIS)
Holan, S.
1978-01-01
The new results achieved within the α-decay theory of spherical nuclei with a (2)-(5) integral formula, unaffected by arbitrary parameters, taking into account the finite shape of the α particle and using a basis of Woods-Saxon uniparticle functions to describe initial and final nuclei, may be summarized as follows: Through α-width calculations performed for many spherical nuclei it has been proved that experimental classifying of α-transition into favoured and unfavoured transitions as well as the hyperfine structure of the transitions can be theoretically explained if considered the nucleon-nucleon correlations in the description of initial and final nuclei; The absolute values of the theoretical α-widths obtained are about 10 2 times smaller compared to the experimental ones. This might be due to an oversimplified approximation of the α-particle-daughter nucleus interaction potential or either to an inaccuracy of the model functions used in describing nucleus decay in the surface area. (author)
Effective interactions in p-shell nuclei and the realistic interactions - I
International Nuclear Information System (INIS)
Upadhyaya, G.K.; Joshi, K.P.
1984-04-01
The effective interaction of Jain et al. derived from the Yale interaction by including the prominent core polarization diagrams is analyzed in terms of the interaction radial integrals and their spin tensor components. The interaction is also compared with some phenomenological effective interactions. The general features of the effective force in the 1 p shell region are discussed. (author)
Investigation of the rotational nuclei 167168Hf and 170171W and the shell-model nucleus 26Mg
International Nuclear Information System (INIS)
Arciszewski, H.F.R.
1984-01-01
Two gamma-gamma coincidence experiments on neighbouring nuclei that exhibit the backbending phenomenon are described. The first experiment performed with the cyclotron of the KVI at Groningen is an investigation of 167 Hf and 168 Hf, whereas in the second experiment, performed at the cyclotron facility of Louvain University, high spin states are studied and compared with predictions of the cranked shell model. A new method for the correction of the large background of Compton-scattered events is described. Apart from this, an investigation of the single particle (d,p) transfer reaction at 26 Mg has been performed with the van de Graaff tandem accelerator at 14 MeV. Specroscopic factors are presented for many levels up to an excitation energy of 8 MeV. Several new spin assignments could be made. (Auth.)
International Nuclear Information System (INIS)
Chen, F. Q.; Sun, Y.
2013-01-01
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 K π = 0 + states in the Gd isotopes have characters of shape vibration. (authors)
A study of the (p,pn) reaction on 1p shell nuclei at 46 MeV
International Nuclear Information System (INIS)
Miller, C.A.
1974-01-01
The (p,pn) reaction on four 1p shell nuclei, 6 Li, 9 Be, 13 C and 12 C, as well as the 6 Li(p,2p) reaction, have been studied at 46 MeV. The 6 Li(p,pn) cross section was found to be approximately four times that for (p,2p) and to have a very different angular dependence. Both reactions show the s-state admixture in 6 Li observed with (p,2p) at higher energies. For all of the target nuclei, the cross sections have features that cannot be fitted by a renormalized Plane Wave Impulse Approximation (PWIA) calculation. A zero range distorted wave calculation was found to be in only fair agreement with the 9 Be and 13 C data. The overall magnitudes of the results of the calculation were found to be very sensitive to the RMS radii of the bound state wave functions of the knocked-out neutrons. (author)
Intruder states in sd-shell nuclei: from 1p-1t to np-nt in Si isotopes
International Nuclear Information System (INIS)
Goasduff, A.
2012-01-01
New large-scale shell-model calculations with full 1ℎω valence space for the sd-nuclei has been used for the first time to predict lifetimes of positive and negative parity states in neutron rich Si isotopes. The predicted lifetimes (1 - 100 ps) fall in the range of the differential Doppler shift method. Using the demonstrator of the European next generation γ-ray array, AGATA, in coincidence with the large acceptance PRISMA magnetic spectrometer from LNL (Legnaro) and the differential plunger of the University of Cologne, lifetimes of excited states in 32;33 Si and 35;36 S nuclei were measured. In a second step, the nℎω structure in the stable 28 Si nucleus was also studied. 28 Si is an important nucleus in order to understand the competition between mean-field and cluster structures. It displays a wealth of structures in terms of deformation and clustering. Light heavy-ion resonant radiative capture 12 C+ 16 O has been performed at energies below the Coulomb barrier. The measure γ-spectra indicate for the first time at these energies that the strongest part of the resonance decay proceeds though intermediate states around 10 MeV. Comparisons with previous radiative capture studies above the Coulomb barrier have been performed and the results have been interpreted in terms of a favoured feeding of T=1 states in the 28 Si self-conjugate nucleus. (author)
Gamow-Teller transitions and proton-neutron pair correlation in N =Z odd-odd p -shell nuclei
Morita, Hiroyuki; Kanada-En'yo, Yoshiko
2017-10-01
We have studied the Gamow-Teller (GT) transitions from N =Z +2 neighbors to N =Z odd-odd nuclei in the p -shell region by using isospin-projected and β γ -constraint antisymmetrized molecular dynamics combined with the generator coordinate method. The calculated GT transition strengths from 0+1 states to 1+0 states such as 6He(01+1 ) →6Li(11+0 ) , 10Be(01+1 ) →10B(11+0 ) , and 14C(01+1 ) →14N(12+0 ) exhaust more than 50% of the sum rule. These N =Z +2 initial states and N =Z odd-odd final states are found to dominantly have S =0 ,T =1 n n pairs and S =1 ,T =0 p n pairs, respectively. Based on the two-nucleon (N N ) pair picture, we can understand the concentration of the GT strengths as the spin-isospin-flip transition n n (S =0 ,T =1 )→p n (S =1 ,T =0 ) in L S coupling. The GT transition can be a good probe to identify the spin-isospin partner states with n n pairs and p n pairs of N =Z +2 and N =Z odd-odd nuclei, respectively.
Study of the (p,pn) reaction on 1p shell nuclei at 46 MeV
Energy Technology Data Exchange (ETDEWEB)
Miller, C A
1974-01-01
The (p,pn) reaction on four 1p shell nuclei, /sup 6/Li, /sup 9/Be, /sup 13/C and /sup 12/C, as well as the /sup 6/Li(p,2p) reaction, have been studied at 46 MeV. The /sup 6/Li(p,pn) cross section was found to be approximately four times that for (p,2p) and to have a very different angular dependence. Both reactions show the s-state admixture in /sup 6/Li observed with (p,2p) at higher energies. For all of the target nuclei, the cross sections have features that cannot be fitted by a renormalized Plane Wave Impulse Approximation (PWIA) calculation. A zero range distorted wave calculation was found to be in only fair agreement with the /sup 9/Be and /sup 13/C data. The overall magnitudes of the results of the calculation were found to be very sensitive to the RMS radii of the bound state wave functions of the knocked-out neutrons.
Energy Technology Data Exchange (ETDEWEB)
Vargas, Carlos E.; Bagatella-Flores, Norma [Universidad Veracruzana, Facultad de Fisica, Veracruz (Mexico); Velazquez, Victor [Universidad Nacional Autonoma de Mexico, Facultad de Ciencias, Mexico D.F. (Mexico); Lerma-Hernandez, Sergio [Universidad Veracruzana, Facultad de Fisica, Veracruz (Mexico); Universidad Nacional Autonoma de Mexico, Instituto de Ciencias Nucleares, Mexico D.F. (Mexico)
2017-04-15
The large collectivity observed in the rare-earth region of the nuclear landscape is well known. The microscopic studies are difficult to perform in this region due to the enormous size of the valence spaces, a problem that can be avoided by means of the use of symmetry-based models. Here we present calculations for electromagnetic properties of {sup 160-170}Dy nuclei within the pseudo-SU(3) scheme. The model Hamiltonian includes the preserving symmetry Q.Q term and the symmetry-breaking Nilsson and pairing terms, systematically parametrized for all members of the chain. The model is used to calculate B(E2) and B(M1) inter-band transition strengths between the ground state, γ and β-bands. In addition, we present results for quadrupole moments and g factors in these rotational bands. The results show that the pseudo-SU(3) shell model is a powerful microscopic theory for a description of electromagnetic properties of states in the normal parity sector in heavy deformed nuclei. (orig.)
International Nuclear Information System (INIS)
Carraz, L.-C.
1974-01-01
Chemical separation techniques have been developed which make it possible to obtain a certain number of isotopes presenting anomalies in the fission efficiencies (near the magic shell N=82). A short description is given of the fission phenomenon by analysing the selection of isotopes investigated; it is shown how it was possible to explain the results by means of computers and the various chemical separations perfected are described. Thus a study was made of the 144 La direct γ spectrum. It was shown that the anomalies in the fission efficiencies of certain nuclei are apparent only. Hence, it is the presence of isomers and the distribution of the corresponding efficiency between two isomers which are the cause of the apparent weakness of the efficiency of 134 I, 136 I and 136 Cs, and of certain isotopes of Nb(Z=41). The nuclear spectrometry of nuclei of the area N=82 has made it possible to extend the existence of a metastable state to 136 Xe and 138 Ba. The value of the energies of the first 2 + , 4 + , 6 + levels and the half life duration of the 6 + metastable state are given. The discussion of the results and of the models show that the interpretation of the 0 + , 2 + , 4 + of the 82 neutron nuclei by means of a two quasi-particle (protons) model gives a fairly satisfactory description of the various experimental events: elastic scattering, gamma spectrometry and proton transfer reactions; on the other hand the interpretation of higher energy levels, requires the use of more complicated configurations [fr
Study of nickel nuclei by (p,d) and (p,t) reactions. Shell model interpretation
International Nuclear Information System (INIS)
Kong-A-Siou, D.-H.
1975-01-01
The experimental techniques employed at the Nuclear Science Institute (Grenoble) and at Michigan State University are described. The development of the transition amplitude calculation of the one-or two-nucleon transfer reactions is described first, after which the principle of shell model calculations is outlined. The choices of configuration space and two-body interactions are discussed. The DWBA method of analysis is studied in more detail. The effects of different approximations and the influence of the parameters are examined. Special attention is paid to the j-dependence of the form of the angular distributions, on effect not explained in the standard DWBA framework. The results are analysed and a large section is devoted to a comparative study of the experimental results obtained and those from other nuclear reactions. The spectroscopic data obtained are compared with the results of shell model calculations [fr
Pseudo SU(3) shell model: Normal parity bands in odd-mass nuclei
International Nuclear Information System (INIS)
Vargas, C.E.; Hirsch, J.G.; Draayer, J.P.
2000-01-01
A pseudo shell SU(3) model description of normal parity bands in 159 Tb is presented. The Hamiltonian includes spherical Nilsson single-particle energies, the quadrupole-quadrupole and pairing interactions, as well as three rotor terms. A systematic parametrization is introduced, accompanied by a detailed discussion of the effect each term in the Hamiltonian has on the energy spectrum. Yrast and excited band wavefunctions are analyzed together with their B(E2) values
International Nuclear Information System (INIS)
Saha, S.; Palit, R.; Trivedi, T.; Sethi, J.; Joshi, P.K.; Naidu, B.S.; Donthi, R.; Jadhav, S.; Nanal, V.; Pillay, R.G.; Jain, H.C.; Kumar, S.; Biswas, D.C.; Mukherjee, G.; Saha, S.
2011-01-01
Information on the high-spin states of nuclei promises to provide stringent test of the interaction of the Hamiltonian used in the calculation due to smaller basis space for high J-values. It is reported in a recent shell model review that no interaction is optimized for the region of interest around N = 50 and Z = 40 shell closure. The detailed spectroscopic information of the medium and high spin states in these nuclei is required to understand the shape transition between spherical and deformed shapes at N =60 as the higher orbitals are filled. Structure of isomers near shell closure carries important information of, for example, the extent of core excitation. In the present work, the spectroscopic study of the high spin states of 89 Zr isotope have been discussed
Quero, D.; Vardaci, E.; Kozulin, E. M.; Zagrebaev, V. A.; Corradi, L.; Pulcini, A.; La Rana, G.; Itkis, I. M.; Knyazheva, G. N.; Novikov, K.; Harca, I.; Fioretto, E.; Stefanini, A. M.; Montanari, D.; Montagnoli, G.; Scarlassara, F.; Szilner, S.; Mijatović, T.; Trzaska, W. H.
2018-05-01
Multi-nucleon transfer reactions are nowadays the only known mean to produce neutron-rich nuclei in the Terra Incognita. The closed-shell region N=126 is crucial for both studying shell-quenching in exotic nuclei and the r-process, being its last “waiting-point”. The choice of suitable reactions is challenging and a favorable case is 136Xe+208Pb, near the Coulomb barrier, because their neutron shell-closures play a stabilizing role, favoring the proton-transfer from lead to xenon. TOF-TOF data were analyzed to reconstruct the mass-energy distribution of the primary fragments. Preliminary results of an experiment held at Laboratori Nazionali di Legnaro with PRISMA, aimed at A and Z identification of the products, will be shown.
Off-shell effects in the coherent π0 photoproduction off nuclei
International Nuclear Information System (INIS)
Chumbalov, A.A.; Kamalov, S.S.
1987-01-01
A strong sensitivity of coherent π 0 -meson photoproduction on nuclei to different ω reaction energy change in elementary amplitude t πγ (ω) is demonstrated. Various assumptions concerning ω behaviour in the extraenergy area can change differential cross sections 1.5-2 times. The best agreement of the DWIA-results with experimental data is obtained at ω being equal to its own value of pion-nucleon system free relativistic Hamiltonian. Such a result agrees with relativistic potential theory effects
Exotic muon-to-positron conversion in nuclei: partial transition sum evaluation by using shell model
International Nuclear Information System (INIS)
Divari, P.C.; Vergados, J.D.; Kosmas, T.S.; Skouras, L.D.
2001-01-01
A comprehensive study of the exotic (μ - ,e + ) conversion in 27 Al, 27 Al(μ - ,e + ) 27 Na is presented. The relevant operators are deduced assuming one-pion and two-pion modes in the framework of intermediate neutrino mixing models, paying special attention to the light neutrino case. The total rate is calculated by summing over partial transition strengths for all kinematically accessible final states derived with s-d shell model calculations employing the well-known Wildenthal realistic interaction
Shell model estimate of electric dipole moments in medium and heavy nuclei
Directory of Open Access Journals (Sweden)
Teruya Eri
2015-01-01
Full Text Available Existence of the electric dipole moment (EDM is deeply related with time-reversal invariance. The EDMof a diamagnetic atom is mainly induced by the nuclear Schiff moment. After carrying out the shell model calculations to obtain wavefunctions for Xe isotopes, we evaluate nuclear Schiff moments for Xe isotopes to estimate their atomic EDMs. We estimate the contribution from each single particle orbital for the Schiff moment. It is found that the contribution on the Schiff moment is very different from orbital to orbital.
Shell model estimate of electric dipole moments in medium and heavy nuclei
Directory of Open Access Journals (Sweden)
Teruya E.
2014-03-01
Full Text Available It is evidence for an extension of the Standard Model in particle physics, if static electric dipole moments (EDMs are measured for any elementary particle. The nuclear EDM arises mainly from two sources: one comes from asymmetric charge distribution in a nucleus and the other is due to the nucleon intrinsic EDM. We estimate the nuclear EDMs from two sources for the 1/21+ states in Xe isotopes by a shell model approach using full orbitals between magic numbers 50 and 82.
Dynamics of valence-shell electrons and nuclei probed by strong-field holography and rescattering
Walt, Samuel G.; Bhargava Ram, Niraghatam; Atala, Marcos; Shvetsov-Shilovski, Nikolay I; von Conta, Aaron; Baykusheva, Denitsa; Lein, Manfred; Wörner, Hans Jakob
2017-01-01
Strong-field photoelectron holography and laser-induced electron diffraction (LIED) are two powerful emerging methods for probing the ultrafast dynamics of molecules. However, both of them have remained restricted to static systems and to nuclear dynamics induced by strong-field ionization. Here we extend these promising methods to image purely electronic valence-shell dynamics in molecules using photoelectron holography. In the same experiment, we use LIED and photoelectron holography simultaneously, to observe coupled electronic-rotational dynamics taking place on similar timescales. These results offer perspectives for imaging ultrafast dynamics of molecules on femtosecond to attosecond timescales. PMID:28643771
Scheck, M.; Ponomarev, V. Yu.; Fritzsche, M.; Joubert, J.; Aumann, T.; Beller, J.; Isaak, J.; Kelley, J. H.; Kwan, E.; Pietralla, N.; Raut, R.; Romig, C.; Rusev, G.; Savran, D.; Schorrenberger, L.; Sonnabend, K.; Tonchev, A. P.; Tornow, W.; Weller, H. R.; Zilges, A.; Zweidinger, M.
2013-10-01
Background: Within the last decade, below the giant dipole resonance the existence of a concentration of additional electric dipole strength has been established. This accumulation of low-lying E1 strength is commonly referred to as pygmy dipole resonance (PDR).Purpose: The photoresponse of 60Ni has been investigated experimentally and theoretically to test the evolution of the PDR in a nucleus with only a small neutron excess. Furthermore, the isoscalar and isovector M1 resonances were investigated.Method: Spin-1 states were excited by exploiting the (γ,γ') nuclear resonance fluorescence technique with unpolarized continuous bremsstrahlung as well as with fully linearly polarized, quasimonochromatic, Compton-backscattered laser photons in the entrance channel of the reaction.Results: Up to 10 MeV a detailed picture of J=1 levels was obtained. For the preponderant number of the individual levels spin and parity were firmly assigned. Furthermore, branching ratios, transition widths, and reduced B(E1) or B(M1) excitation probability were calculated from the measured scattering cross sections. A comparison with theoretical results obtained within the quasiparticle phonon model allows an insight into the microscopic structure of the observed states.Conclusions: Below 10 MeV the directly observed E1 strength [∑B(E1)↑=(153.8±9.5) e2(fm)2] exhausts 0.5% of the Thomas-Reiche-Kuhn sum rule. This value increases to 0.8% of the sum rule [∑B(E1)↑=(250.9±31.1) e2(fm)2] when indirectly observed branches to lower-lying levels are considered. Two accumulations of M1 excited spin-1 states near 8 and 9 MeV excitation energy are identified as isoscalar and isovector M1 resonances dominated by proton and neutron f7/2→f5/2 spin-flip excitations. The B(M1)↑ strength of these structures accumulates to 3.94(27)μN2.
Negative pion capture in atomic nuclei near the closed neutron shell at N=82
International Nuclear Information System (INIS)
Butsev, V.S.; Chultem, D.; Zhivotov, I.N.
1981-01-01
The results of studies of the excitation of high spin states in stopped π - -absorption in Nd, Pr, Ce, La and Ba nuclei are reported. States with spins 7 - , 8 - and 19/2 - have been identified. The isomeric ratios for the isotopes 131 Ba and 133 Ba have been determined to be equal to σsub(m)/σsub(g)=(5.1+-0.5) and (2.2+-0.3), respectively. For the isomers sup(134m)Cs and sup(135m)Cs the isotopic ratio is found to be σsub(msub(1))/σsub(msub(2))=8.2+-2.3. The distinguishing features of the mechanisms of excitation of high spin states by stopped π - and fast protons are discussed [ru
Electromagnetic properties of neutron-rich nuclei adjacent to the Z=50 shell closure
Directory of Open Access Journals (Sweden)
M. Rejmund
2016-02-01
Full Text Available Low-lying high-spin yrast states in the exotic odd–odd isotopes 124–128Sb (Z=51 and 118–128In (Z=49, studied for the first time, show a striking difference in their observed γ-ray decay. With a single valence proton particle/hole occupying the g7/2/g9/2 spin-orbit partners, dominant electric quadrupole transitions occur in Sb as opposed to magnetic dipole transitions in In. The observed properties are explained on the basis of general principles of symmetry and with large-scale shell-model calculations, and reveal novel aspects of the competition between the neutron–proton interaction and the like-nucleon pairing interaction.
International Nuclear Information System (INIS)
Gils, H.J.
1984-12-01
The radial size and shape of the distribution of nucleons - i.e. the sum of protons and neutrons - in atomic nuclei of the 1fsub(7/2) shell is investigated in the present work. The experimental basis of the studies are differential cross sections of elastic α particle scattering by sup(40,42,43,44,48)Ca, 50 Ti, 51 V, 52 Cr precisely measured over a wide angular range at the 104 MeV α particle beam from the Karlsruhe Isochronous Cyclotron. The experimental cross sections are analyzed using so-called 'model independent' optical potentials by which the data are very well reproduced. The error bands of these potentials are determined in a well-defined form from the analyses. The high sensitivity of the data to the radial form of the real optical potential justifies, in principle, that the experiments are a suitable tool for investigating nuclear density distributions. Some pre-informations on this question are obtained from the optical potential analyses. For a more direct access to the nuclear matter distributions - in particular to differences between neighbouring nuclei - a semimicroscopic reaction model is presented which on the one hand is based on a fully microscopic many body approach. On the other hand all quantities being not of particular interest for the results are treated in a phenomenological way. Thereby, it is possible to reproduce the experimental cross sections as well as by the 'model independent' potentials and to obtain full consistency between the two approaches. This has not been achieved by any other microscopic reaction model. (orig./HSI) [de
Resonant heavy-ion elastic scattering from s-d shell nuclei
International Nuclear Information System (INIS)
DeVries, R.M.
1978-01-01
Angular distributions at angles 130 less than theta/sub cm/ less than 180 0 were measured for 12 C + 28 Si, 32 S, 40 Ca as well as 9 Be, 13 C + 28 Si in the energy range 20 MeV less than or equal to E/sub cm/ less than or equal to 35 MeV. Cross sections rising towards 180 0 are observed for all reactions. Excitation functions for the back-angle enhancement show distinct structures, most pronounced for 12 C + 28 Si. Angular distributions for 12 C, especially those corresponding to peaks in the excitation function show oscillations of the type vertical bar P/sub J/(cos theta) vertical bar 2 . The 12 C back-angle enhancement decreases with target mass. Backscattering of the nonalpha nuclei 9 Be and 13 C is reduced by about two orders of magnitude in comparison with 12 C. Similar measurements for the 28 Si( 12 C, 16 O) 24 Mg reaction and 16 O + 24 Mg elastic scattering allow comparison of reaction data with the corresponding entrance and exit channel data. Standard theoretical approaches fail to explain all the observed effects
Shell effects in fission and quasi-fission of heavy and superheavy nuclei
Energy Technology Data Exchange (ETDEWEB)
Itkis, M.G. E-mail: itkis@flnr.jinr.ru; Aeystoe, J.; Beghini, S.; Bogachev, A.A.; Corradi, L.; Dorvaux, O.; Gadea, A.; Giardina, G.; Hanappe, F.; Itkis, I.M.; Jandel, M.; Kliman, J.; Khlebnikov, S.V.; Kniajeva, G.N.; Kondratiev, N.A.; Kozulin, E.M.; Krupa, L.; Latina, A.; Materna, T.; Montagnoli, G.; Oganessian, Yu.Ts.; Pokrovsky, I.V.; Prokhorova, E.V.; Rowley, N.; Rubchenya, V.A.; Rusanov, A.Ya.; Sagaidak, R.N.; Scarlassara, F.; Stefanini, A.M.; Stuttge, L.; Szilner, S.; Trotta, M.; Trzaska, W.H.; Vakhtin, D.N.; Vinodkumar, A.M.; Voskressenski, V.M.; Zagrebaev, V.I
2004-04-05
Results of the experiments aimed at the study of fission and quasi-fission processes in the reactions {sup 12}C+{sup 204}Pb, {sup 48}Ca+{sup 144,154}Sm, {sup 168}Er, {sup 208}Pb, {sup 244}Pu, {sup 248}Cm; {sup 58}Fe+{sup 208}Pb, {sup 244}Pu, {sup 248}Cm, and {sup 64}Ni+{sup 186}W, {sup 242}Pu are presented in the work. The choice of the above-mentioned reactions was inspired by recent experiments on the production of the isotopes {sup 283}112, {sup 289}114 and {sup 283}116 at Dubna [1],[2] using the same reactions. The {sup 58}Fe and {sup 64}Ni projectiles were chosen since the corresponding projectile-target combinations lead to the synthesis of even heavier elements. The experiments were carried out at the U-400 accelerator of the Flerov Laboratory of Nuclear Reactions (JINR, Russia), the XTU Tandem accelerator of the National Laboratory of Legnaro (LNL, Italy) and the Accelerator of the Laboratory of University of Jyvaskyla (JYFL, Finland) using the time-of-flight spectrometer of fission fragments CORSET[3] and the neutron multi-detector DEMON[4],[5]. The role of shell effects and the influence of the entrance channel on the mechanism of the compound nucleus fusion-fission and the competitive process of quasi-fission are discussed.
Relativistic quasiparticle time blocking approximation: Dipole response of open-shell nuclei
International Nuclear Information System (INIS)
Litvinova, E.; Ring, P.; Tselyaev, V.
2008-01-01
The self-consistent relativistic quasiparticle random-phase approximation (RQRPA) is extended by the quasiparticle-phonon coupling (QPC) model using the quasiparticle time blocking approximation (QTBA). The method is formulated in terms of the Bethe-Salpeter equation (BSE) in the two-quasiparticle space with an energy-dependent two-quasiparticle residual interaction. This equation is solved either in the basis of Dirac states forming the self-consistent solution of the ground state or in the momentum representation. Pairing correlations are treated within the Bardeen-Cooper-Schrieffer (BCS) model with a monopole-monopole interaction. The same NL3 set of the coupling constants generates the Dirac-Hartree-BCS single-quasiparticle spectrum, the static part of the residual two-quasiparticle interaction and the quasiparticle-phonon coupling amplitudes. A quantitative description of electric dipole excitations in the chain of tin isotopes (Z=50) with the mass numbers A=100,106,114,116,120, and 130 and in the chain of isotones with (N=50) 88 Sr, 90 Zr, 92 Mo is performed within this framework. The RQRPA extended by the coupling to collective vibrations generates spectra with a multitude of 2q x phonon (two quasiparticles plus phonon) states providing a noticeable fragmentation of the giant dipole resonance as well as of the soft dipole mode (pygmy resonance) in the nuclei under investigation. The results obtained for the photo absorption cross sections and for the integrated contributions of the low-lying strength to the calculated dipole spectra agree very well with the available experimental data
International Nuclear Information System (INIS)
Baghdadi, Ahmed.
1974-01-01
The overlap of t and d or 3 He and d wave functions may be measured by one neutron transfer in (d,t) or one proton transfer in ( 3 He,d). The measurement of the resulting normalization constant has been performed in subcoulombic conditions in the case of 58 Ni( 3 He,d) 59 Cu and 60 Ni( 3 He,d) 61 Cu leading to the first 3/2 - and 1/2 - states with a position sensitive detector in a Buechner spectrograph. The result: D 2 =2.7+-0.2 10 4 MeV 2 fm 3 is in agreement with the D 2 measurement for (t,d) reactions [3.1+-0.2 10 4 MeV 2 fm 3 ] and with the theoretical value proposed by L.J.B. Goldfarg and coworkers. This result was used for a determination of the spectroscopic factors of the 1.379MeV 3/2 - state, the 1.507MeV 1/2 - state and the 1.758MeV 3/2 - state in 57 Co. The subcoulombic approximation is also shown to be valid even in the case of (d,p) reactions, by the measurement of angular distributions and excitation curves of 60 Ni(d,p) reactions leading to the excited states at 4.760MeV (l=2) and 4.907MeV (l=0). In the second part, some spectroscopic factors in the s-d shell were measured by ( 3 He,d) reactions at MP Tandem energies. In the case of 27 Al( 3 He,d) 28 Si (states at 4.62, 6.88, 6.89, 9.32 and 0.38MeV) the normalization constant D 0 2 (deduced from the subcoulombic D 2 value) together with the first order finite range approximation leads to spectroscopic factors in good agreement with Wildenthal theoretical results. For 28 Si( 3 He,d) 29 p however, the values are too high compared to 29 Si. The conclusion is that it is better to use the DWBA treatment at subcoulombic energies everytime the experimental conditions may be fulfilled [fr
International Nuclear Information System (INIS)
Marchix, A.
2007-11-01
The aim of this work is to study the influence of shell correction energy on the deexcitation of superheavy nuclei. For that purpose, a new statistical code, called Kewpie2, which is based on an original algorithm allowing to have access to very weak probabilities, was developed. The results obtained with Kewpie2 have been compared to the experimental data on residue cross sections obtained by cold fusion (Z=108 to Z=113) and by hot fusion (Z=112, Z=114 and Z=116), as well as data on fission times (Z=114, Z=120 and Z=126). Constraints on the microscopic structure of the studied nuclei have been obtained by means of the shell correction energy. By adjusting the intrinsic parameters of the models of fusion in order to reproduce the data on the fusion cross sections, this study shows the necessity of decreasing very strongly the shell correction energy predicted by the calculations of Moller and Nix, during the study of the residues cross sections as well for the nuclei produced by cold fusion as by hot fusion. On the other hand, during the confrontation of the results of Kewpie2 to the data on mean fission times, it is rather advisable to increase it. A shift of the proton shell closure predicted for Z=114 by the calculations of Moller and Nix towards larger Z would allow to explain these opposite conclusions. In this thesis, we also have shown the significant influence of the inclusion of isomeric states on fission times for the superheavy nuclei. (author)
International Nuclear Information System (INIS)
Delchambre, P.; Von der Hardt, P.
1989-01-01
This report summarizes the pre-project studies concerning the PHEBUS FP facility. After recalling the programme objectives, it describes the projected modifications to the PHEBUS reactor, outlines new installations and justifies the selected options
International Nuclear Information System (INIS)
Mach, H.; Baluyut, A.-M.; Smith, D.; Ruchowska, E.; Koester, U.; Fraile, L. M.; Penttilae, H.; Aeystoe, J.; Elomaa, V.-V.; Eronen, T.; Hakala, J.; Jokinen, A.; Karvonen, P.; Kessler, T.; Moore, I. D.; Rahaman, S.; Rissanen, J.; Ronkainen, J.; Ronkanen, P.; Saastamoinen, A.
2009-01-01
Using the Advanced Time-Delayed method we have studied transition rates in several neutron-rich nuclei at the magic shell closures. These include the heavy Co and Fe nuclei just below the Z = 28 shell closure at the point of transition from spherical to collective structures. Of particular interest is 63 Fe located exactly at the point of transition at N = 37. A substantial increase in the information on this nucleus was obtained from a brief fast timing study conducted at ISOLDE. The new results indicate that 63 Fe seems to depart from a simple shell model structure observed for heavier N = 37 isotones of 65 Ni and 67 Zn.Another region of interest are the heavy Cd and Sn nuclei at N = 72, 74 and the properties of negative parity quasi-particle excitations. These experiments, performed at the IGISOL separator at Jyvaeskylae, revealed interesting properties of the E2 rates in the sequence of E2 transitions connecting the 10 + , 8 + , 6 + , 4 + , 2 + and 0 + members of the multiplet of levels in 122 Sn due to neutrons in the h 11/2 orbit.
Energy Technology Data Exchange (ETDEWEB)
Gillet, V [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires
1962-07-01
A unified theory for the spectra of nuclei with closed shells, based on the elementary particle-hole excitation of these systems, is applied to a study of carbon-12, oxygen-16 and calcium-40. Two approximations are made. The first consists in diagonalizing the residual two-body interaction in a limited sub-space having one particle and one hole configurations. Its validity depends on the high energy necessary for exciting a particle-hole pair. The second approximation consists in re-summing the infinite sub-series of the particle-hole diagrams. It is equivalent to the Hartree-Fock method depending on the time, or to Quasi-Boson method. Its domain of validity in the nuclear case is not thoroughly Understood. The summed diagrams are preponderant at the high density limit, when the nuclear density is about unity. The violation of the Pauli principle in this approximation is only justified if the number of excited pairs is small with respect to the number of particle states available; in the case of light nuclei the degeneracies of the shells are small. Nevertheless this approximation, which postulates the existence of an average nuclear field, varying slowly with time with respect to the nucleons periods has the merit of being self-consistent, of giving orthogonal proper states in the non-physical state of the mass centre, and of improving the calculation of the summation rules. In order to determine and to limit the role of phenomenology in the results obtained using these approximations, a maximum amount of experimental data is calculated. By applying method of least squares to fourteen energy levels of oxygen and carbon, the region of optimum agreement in the effective interaction parameters is determined. This region is in part a function of the numerical approximations made. We hope that it will keep its significance when the theory is improved. It is compatible with certain characteristics of free nucleon-nucleon scattering. The present research favours the
International Nuclear Information System (INIS)
Souw, Kenghok.
1975-01-01
A new high efficiency plastic scintillation pair spectrometer was used to measure the E0 branching ratio GAMMAsub(π)/GAMMA(tot) (GAMMAsub(π)=pair emission partial width, GAMMA(tot)=total width) of the transition from the first excited Jsup(π)=0 + state to the Jsup(π)=0 + ground state in some even-even nuclei of the 2s-1d shell. Experiments were performed on 18 O, 26 Mg, 30 Si, 32 S, 34 S and 38 Ar nuclei. The method consisted in detecting the electron and positron of the pair in coincidence in two telescopes. A surface barrier counter placed downstream the target, working in coincidence with the spectrometer, allowed the relevant pair-decays to be selected and the feeding yield to be determined from direct spectra. The branching ratios were such directly determined. These ratios combined with the values available for the lifetimes of these states give the monopole matrix elements Msub(π). The single particle strength of these decays passes through a minimum in the middle of the shell ( 30 Si) and reaches a maximum around the closed shells ( 18 O, and 48 Ca) [fr
Energy Technology Data Exchange (ETDEWEB)
Gupta, Anuradha; Singh, Suram; Bharti, Arun [University of Jammu, Department of Physics and Electronics, Jammu (India); Khosa, S.K. [Central University of Jammu, Department of Physics and Astronomical Sciences, Jammu (India); Bhat, G.H.; Sheikh, J.A. [University of Kashmir, Department of Physics, Srinagar (India)
2017-01-15
By employing a systematically parametrized Hamiltonian and the best fit of the various input parameters, high-spin yrast energy states for an isotopic chain of odd mass {sup 59-69}Cu nuclei have been investigated by using a novel computational quantum mechanical framework-projected shell model. Comparison of calculations and experiments yields good agreement. The present study of various intriguing nuclear structure properties along the yrast lines in these odd proton isotopes reflects some interesting informative nuclear physics results. The calculations successfully describe the formation of the yrast level structures from multi-quasi-particle configurations based on πf x νg bands for {sup 59-69}Cu isotopes. The present calculations indicate the evolution of the nuclear structure near the magic nuclei, Ni, and also provide an indication of coexistence of both, collective as well as single-particle, levels for {sup 69}Cu nucleus at N=40. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Igashira, Masayuki; Lee, Sam Yol; Mizuno, Satoshi; Hori, Jun-ichi [Tokyo Inst. of Tech. (Japan). Research Lab. for Nuclear Reactors; Kitazawa, Hideo
1998-03-01
Measurements of gamma rays from keV-neutron resonance capture by {sup 19}F, {sup 23}Na, and {sup 27}Al, which are odd-Z nuclei in the 2s-1d shell region, were performed, using an anti-Compton HPGe spectrometer and a pulsed neutron source by the {sup 7}Li(p,n){sup 7}Be reaction. Capture gamma rays from the 27-, 49-, and 97-keV resonances of {sup 19}F, the 35- and 53-keV resonances of {sup 23}Na, and the 35-keV resonance of {sup 27}Al were observed. Some results are presented. (author)
International Nuclear Information System (INIS)
Bastin, B.
2007-10-01
For a few years now, a loss of magicity in neutron-rich nuclei near the neutron drip-line at N=28 has been suggested and observed. Deformation in these nuclei has been observed. The deformation was explained in S isotopes as being due to a moderate reduction of the N=28 shell closure together with a proton induced collectivity originating from the near degeneracy of the proton d3/2 and s1/2 orbitals. As a consequence, the observed deformation seems to result from a subtle interplay between neutron and proton excitations. Since the proton configuration in the Si isotopes is expected to be more stable due to the Z=14 sub-shell gap, 42 Si was considered as a key nucleus in order to distinguish the different effects responsible for the structural changes observed at N=28. Even if it is at the limits of our technical possibilities, an in-beam gamma-spectroscopy experiment using two-step fragmentation and one or several nucleons knockout reaction mechanisms was performed at GANIL. The measurement of the energy of the first excited state in 42 Si, combined with the observation of 38,40 Si and the spectroscopy of 41,43 P, has given evidence for the loss of magicity at N=28 far from stability. Modifications of the effective interaction used in modern shell model calculations have been completed following this investigation, increasing its predictive character. This study confirms the role of the tensor force and the density dependence of the spin-orbit interaction in the collapse of the N=28 shell closure. (author)
1994-03-01
Joseph Van Arendonk, deputy executive director of the UN Population Fund (UNFPA), stated in an interview that UNFPA had identified the critical points of success for a family planning (FP) program. First is the public and consistent commitment of the political leadership of a country. Second, very good quality services must be readily available, the clinics should be clean, and the workers well-trained, especially in counseling. Third, services must be accessible and physically near to people, who must be informed of service availability. Fourth, women should have the ability to decide for themselves about their fertility. However, FP should be a joint decision, and therefore education for men is vital. Another important element to success is to have proper service statistics built into the FP program for assessment of the problem of dropping out and for a continuous program evaluation. Other aspects of management are good supervision and control as well as proper logistics. Although the Earth Summit made sustainable development the objective for the year 2000 and beyond, this goal is only viable if it is linked with an appropriate population policy. In population, the same kinds of challenges persist that existed 25 years ago. This is because once contraception is introduced, the relationship between men and women and the whole concept of family are changed, bringing about changes in society.
Deng, Jun-Gang; Zhao, Jie-Cheng; Chu, Peng-Cheng; Li, Xiao-Hua
2018-04-01
In the present work, we systematically study the α decay preformation factors Pα within the cluster-formation model and α decay half-lives by the proximity potential 1977 formalism for nuclei around Z =82 ,N =126 closed shells. The calculations show that the realistic Pα is linearly dependent on the product of valance protons (holes) and valance neutrons (holes) NpNn . It is consistent with our previous works [Sun et al., Phys. Rev. C 94, 024338 (2016), 10.1103/PhysRevC.94.024338; Deng et al., Phys. Rev. C 96, 024318 (2017), 10.1103/PhysRevC.96.024318], in which Pα are model dependent and extracted from the ratios of calculated α half-lives to experimental data. Combining with our previous works, we confirm that the valance proton-neutron interaction plays a key role in the α preformation for nuclei around Z =82 ,N =126 shell closures whether the Pα is model dependent or microcosmic. In addition, our calculated α decay half-lives by using the proximity potential 1977 formalism taking Pα evaluated by the cluster-formation model can well reproduce the experimental data and significantly reduce the errors.
2002-01-01
We propose to perform Coulomb excitation experiments of neutron-rich nuclei in the vicinity of $^{68}$Ni towards $^{78}$Ni using the REX-ISOLDE facility coupled with the highly efficient MINIBALL array. Major changes in the structure of the atomic nucleus are expected around the N = 40 subshell closure. Recent B(E2) measurements suggested that $^{68}$Ni behaves like a doubly magic nucleus while neutron-rich Zn isotopes with N>38 exhibit a sudden increase of B(E2) values which may be the signature of deformation. We would like to check and test these predictions for neutron-rich nuclei in the vicinity of N = 40 and N = 50 shell closures like $^{72}$Zn, $^{74}$Zn, $^{76}$Zn, $^{68}$Ni, $^{70}$Ni. Our calculations show that an energy upgrade from 2.2 to 3 MeV/nucleon will be of crucial importance for a part of our study while some nuclei can still be very efficiently studied at an energy of 2.2 MeV/nucleon. Therefore, to perform our experiment in an efficient way, we request 21 shifts of beam time before the ene...
International Nuclear Information System (INIS)
Khouaja, A.
2003-12-01
Using the direct method, the mean energy integrated reaction cross section was investigated for a wide range of neutron-rich nuclei (N → Ar) at GANIL. Using the parametrisation of S. Kox, 19 new radii measurements (reaction cross sections) were obtained. By the isotopic, isotonic and isospin dependence, the evolution of the strong reduced radius was studied according to the excess of neutrons. New halo effect is proposed to the nuclei of Mg 35 and S 44 . A quadratic parametrization is also proposed for the nuclear radius as a function of the isospin in the region of closed shells N=8 and N=28. In addition, we used a modified version of the Glauber model for studying the tail and matter distribution of nuclei. Indeed, using our new data the effects of the nuclear size (root mean square radii) and the matter distribution (diffusivity) were de-convoluted for each isotope. The root mean square radii of Na and Mg isotopes obtained so far were consistent with the ones from literature. (author)
Study of the anharmonic effects on low-lying states of odd-mass nuclei in 1g sub(9/2)+ shell region
International Nuclear Information System (INIS)
Nakano, Masahiro
1980-01-01
Anharmonic effects on the low-lying states of the odd-mass nuclei in 1g sub(9/2)sup(+) shell region are investigated by introduction of 1, 3, 5 and 7 quasiparticle modes. Special attention is paid to the energy-lowering of anomalous coupling states in N = 41 nuclei and to the spin sequence of so-called ''one-quasiparticle-two-phonon multiplet''. It is shown that one cannot attribute the special-lowering of the energies of the anomalous coupling (j - 2) states to the dynamical effects due to the coupling between the 3-quasiparticle mode and the 5-quasiparticle mode, and is also shown that not only the kinematical effect but also the dynamical effect plays an important role in the energy-lowering of the anomalous coupling (j - 1) states in N = 41 nuclei. The second (j - 2) state is predicted to be the lowest member of one-quasiparticle-two-phonon multiplet by taking account of the kinematical effect for the 5-quasiparticle mode, which corresponds to the experimental fact. (author)
The Hartree-Fock approximation for s-d shell even-even nuclei with N different of Z
International Nuclear Information System (INIS)
Oliveira, P.C. de.
1981-02-01
Using the Hartree-Fock approximation method for 22 Ne, 26 Mg and 30 Si nuclei with different kinds of two-body interactions, the electric quadrupole moments and projected energy levels, of angular momentum J=0,2,4,6..., are determined. The Peierls-Yoccoz projection m ethod is used to determine the wave function with well-defined angular momentum. A comparison is made, with the experimental results and the ones obtained by other authors. (Author) [pt
Magnetic dipole moments of deformed odd-odd nuclei in 2s-1d and 2p-1f shells
Energy Technology Data Exchange (ETDEWEB)
Verma, A K; Garg, V P; Sharma, S D [Punjabi Univ., Patiala (India). Dept. of Physics
1979-01-01
A simple expression is derived for the computation of the magnetic moments of odd-odd nuclei. The computation of magnetic dipole moments is done with and without quenching factors for the last proton and neutron. The results are found to improve for /sup 22/Na, /sup 24/Na, sup(82m)Rb, /sup 14/N, /sup 68/Gd, /sup 54/Mn and /sup 86/Rb with extreme coupling of angular moments.
International Nuclear Information System (INIS)
Wloch, Marta; Gour, Jeffrey R; Piecuch, Piotr; Dean, David J; Hjorth-Jensen, Morten; Papenbrock, Thomas
2005-01-01
We discuss large-scale ab initio calculations of ground and excited states of 16 O and preliminary calculations for 15 O and 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 16 O and promising results for 15 O and 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
Czech Academy of Sciences Publication Activity Database
Dreyfuss, A. C.; Launey, K. D.; Dytrych, Tomáš; Draayer, J. P.; Baker, R. B.; Deibel, C. M.; Bahri, C.
2017-01-01
Roč. 95, č. 4 (2017), č. článku 044312. ISSN 2469-9985 R&D Projects: GA ČR GA16-16772S Institutional support: RVO:61389005 Keywords : C-12 * no-core shell-model * resonance Subject RIV: BE - Theoretical Physics OBOR OECD: Atomic, molecular and chemical physics (physics of atoms and molecules including collision, interaction with radiation, magnetic resonances, Mössbauer effect) Impact factor: 3.820, year: 2016
No-Core Shell Model for A = 47 and A = 49
Energy Technology Data Exchange (ETDEWEB)
Vary, J P; Negoita, A G; Stoica, S
2006-11-13
We apply the no-core shell model to the nuclear structure of odd-mass nuclei straddling {sup 48}Ca. Starting with the NN interaction, that fits two-body scattering and bound state data, we evaluate the nuclear properties of A = 47 and A = 49 nuclei while preserving all the underlying symmetries. Due to model space limitations and the absence of three-body interactions, we incorporate phenomenological interaction terms determined by fits to A = 48 nuclei in a previous effort. Our modified Hamiltonian produces reasonable spectra for these odd-mass nuclei. In addition to the differences in single-particle basis states, the absence of a single-particle Hamiltonian in our no-core approach complicates comparisons with valence effective NN interactions. We focus on purely off-diagonal two-body matrix elements since they are not affected by ambiguities in the different roles for one-body potentials and we compare selected sets of fp-shell matrix elements of our initial and modified Hamiltonians in the harmonic oscillator basis with those of a recent model fp-shell interaction, the GXPF1 interaction of Honma et al. While some significant differences emerge from these comparisons, there is an overall reasonably good correlation between our off-diagonal matrix elements and those of GXPF1.
International Nuclear Information System (INIS)
Bilwes, B.; Bilwes, R.; Diaz, J.; Ferrero, J.L.; Pacheco, J.C.; Ruiz, J.A.
1988-01-01
Experimental data of elastic scattering between nuclei of various structures on a large energy scale has been analyzed in the framework of the folding model by use of the complex effective interaction of Faessler et al (1981). A general good reproduction of the data is obtained if renormalization coefficients for the real and the imaginary parts of the optical potential are introduced. The application of the dispersion relation of Mahaux et al (1986) allows to reproduce the observed energy dependence of the real part of the potential
International Nuclear Information System (INIS)
Brizzi, R.; Fabre de la Ripelle, M.; Lassaut, M.
1999-01-01
The binding energies and root mean square radii obtained from the Integro-Differential Equation Approach (IDEA) and from the Weight Function Approximation (WFA) of the IDEA for an even number of bosons and for 12 C, 16 O and 40 Ca are compared to those recently obtained by the Variational Monte Carlo, Fermi Hypernetted Chain and Coupled Cluster expansion method with model potentials. The IDEA provides numbers very similar to those obtained by other methods although it takes only two-body correlations into account. The analytical expression of the wave function for the WFA is given for bosons in ground state when the interaction pair is outside the potential range. Due to its simple structure, the equations of the IDEA can easily be extended to realistic interaction for nuclei like it has already been done for the tri-nucleon and the 4 He. (authors)
Muon capture by the 1p shell of 10B, 12C and 14N nuclei. Experiments and interpretation
International Nuclear Information System (INIS)
Moura Goncalves, A.C. de.
1980-12-01
The main elements necessary to treat weak interactions in a nucleus including the contributions of exchange meson currents are presented. The case of a transition between an initial (Z,A) nucleus and a final (Z-1,A) nucleus in a well defined bound state is treated. The form of the single body operator taking into account the nucleonic degrees of freedom (impulse approximation) is recalled. The construction of a two-body operator taking mesonic degrees of freedom into account is outlined. Measurements of partial capture rates in 10 B, 12 C and 14 N target nuclei leading to excited bound states of 10 Be, 12 B and 14 C residual nuclei are described. Results are given and comparisons made with the calculations performed, nuclear states being described by various wave functions. Measurements of the polarization of the 1 + ground state of 12 B after N capture in 12 C are briefly described. An attempt is made to interpret the 0 + 1 + transition occurring in the A = 12 triad. A convenient parametrization is obtained from the expression for these observable quantities as a function of the nuclear shape factors. This analysis enables a strict choice to be made from the available wavefunctions. It demonstrates that experimental data are well reproduced by the microscopy approach performed using the effective Sussex potential and single pion exchange currents. Finally, the hitherto unexplored domain of muon capture is tackled. A high energy transfer is involved in which the neutrino remains practically at rest. In this case, the vector part is not very important and the axial current time part contributes as much is the space part. The (μ - ,pn) reaction was used for exploratory measurements in this domain. Practical limits are determined [fr
International Nuclear Information System (INIS)
Raina, P.K.; Sharma, S.K.
1986-12-01
A microscopic description of the recent data on the inelastic electron scattering form factors for the O + → 2 + as well as O + → 4 + transitions in some doubly even Ti, Cr, Fe, Ni and Zn isotopes is attempted in terms of the projected Hartree-Fock-Bogolubov wave functions resulting from realistic effective interactions operating in the 2p-1f shell. It turns out that the available form factor data out to about 2.5fm -1 can be reproduced in most of the cases in a fairly satisfactory manner in terms of reasonable values of effective charges. It is seen that the empirical transition charge densities in Ni and Zn isotopes extracted from the form factor data via the Fourier-Bessel analysis play a decisive role vis-a-vis the choice of a model of core-polarization contributions. (author). 28 refs, 8 figs, 2 tabs
Evolution of the shell structure in medium-mass nuclei: search for the 2d5/2 neutron orbital in 69Ni
International Nuclear Information System (INIS)
Moukaddam, M.
2012-01-01
The harmonic oscillator shell closure at N=40 in 68 Ni is weak and loses its strength when removing (or adding) pair of protons. Calculations performed in this mass region predict a new island of inversion at N=40 similar to the one at N=20. Using a large valence space, the neutron orbital 2d(5/2) is shown to be a crucial ingredient for the interpretation of the nuclear structure at N ∼40. The neutron 1g(9/2) -2d(5/2) energy difference has been determined in 69 Ni beam at 25.14 MeV/u separated by the LISE3 spectrometer was impinging a CD 2 target of 2.6 mg/cm 2 thickness. The experimental setup consisted of CATS/MUST2-S1/EXOGAM detectors coupled to an ionization chamber and a plastic scintillator. The angular moment and spectroscopic factors of the ground state (J π =9/2 + ) and a doublet of states (J π =5/2 + ) around 2.48 MeV corresponding to the population of the 1g(9/2) and the 2d(5/2) orbitals, were obtained from the comparison between the experimental cross-sections as a function of the proton detection angle and ADWA calculations. The spins of the observed states were assigned by comparison to large scale Shell-Model calculations. The position of the 2d(5/2) orbital in 69 Ni has been established for the first time. Our measurements support the hypothesis of a low-lying 2d(5/2) orbital (∼2.5 MeV) with respect to the 1g(9/2) neutron orbital and thus its major role in the structure of the nuclei around N=40. (author)
Optical model analysis of 3He elastic scattering from s-d shell nuclei at 25 MeV
International Nuclear Information System (INIS)
Vernotte, J.; Berrier-Ronsin, G.; Kalifa, J.; Tamisier, R.; Nantes Univ., 44
1982-01-01
Angular distributions of elastically scattered 3 He particles from 16 O, 18 O, 19 F, 23 Na, 24 Mg, 25 Mg, 26 Mg, 27 Al, 28 Si, 29 Si, 30 Si, 31 P, 35 Cl, 37 Cl, 39 K and 40 Ca nuclei were measured at 25 MeV bombarding energy. The absolute differential cross-section data were analysed in the framework of the standard optical model with either a volume or a surface imaginary part. Three families of parameters were considered. For all these families, the real potential volume integral Jsub(R) per interacting nucleon pair decreases as the mass number A increases. The family with Jsub(R) = 380 MeV x fm 3 for 40 Ca and Jsub(R) = 590 MeV x fm 3 for 16 O has been identified with the unique family obtained at higher energies, and is therefore considered as the 'physical' family. The matter and charge radii deduced from the analysis are presented. The charge radii are compared with the ones obtained from muonic X-ray transitions and electron scattering measurements. (orig.)
International Nuclear Information System (INIS)
Kitazawa, H.; Igashira, M.; Shimizu, M.; Muto, K.; Oda, T.; Achiha, Y.; Lee, Y.; Mukai, N.
1992-01-01
Observations have been performed for electromagnetic transitions from the broad s-wave neutron resonances at 658 keV in 24 Mg, at 180 keV in 28 Si, and at 103 keV in 32 S. Capture gamma rays were measured with an anti-Compton NaI(Tl) detector, using a neutron time-of-flight technique. E1 and M1 transitions from those resonances to low-lying states with a strong single-particle character were found. The deduced partial radiative widths for E1 transition are in excellent agreement with the Lane-Mughabghab valence-capture model calculations taking the neutron effective charge, -Ze/A. Moreover, it is shown that essential features of the observed E1 and M1 transitions can be well explained by assuming a configuration-mixing wave function, Ψ i (1/2 + )=a(0 + direct-product 1/2 + )+b(1 + direct-product 1/2 + )+c(1 + direct-product 3/2 + ), for each resonance. The M1 transition strengths are compared also with more detailed shell model calculations in the model space of full (sd) n configurations, using the Wildenthal effective interaction
Study of deep inelastic reactions on sd-shell nuclei with 100 MeV α-particles
International Nuclear Information System (INIS)
Seniwongse, G.
1985-04-01
Energy spectra and angular distributions of light particles (p, d, t, 3 He, α) were measured. As projectiles α-particles with the incident energy of 100 MeV were used. The measurement data result from an inclusive measurement of the reactions on 24 Mg, 25 Mg, 26 Mg, 27 Al, 28 Si. The double differential cross sections and the angular distributions were analyzed in the framework of the exciton-coalescence model. Thereby model parameters as the initial exciton number n 0 one-particle state density, and coalescence radii were determined. From the model analysis it can be concluded that n 0 =5 describes the data optimally contrarily to earlier results. The proton spectra can be explained by different one-particle state densities with pairing effects. The probability for the formation of complex particles seems to be independent from the structure of the target nuclei studied here. The calculated cross sections agree well with the measured values. This is valid both for the angle-integrated spectra and for the angular distributions. The agreement was especially well for the angle-integrated cross sections of the (α, p) reaction over the whole spectrum. For the complex particles the agreement in the energy of the produced particle was well up to about 60 MeV, i.e. before the superposition from the breakup respectively direct reactions begins. These reactions are indeed not regarded in the model. The measurement data and the calculated angular distributions agree for all types of particles at measurement angles below about 60 0 well. At larger angles the calculated values are too large. The reasons for this are not yet clear. (orig.) [de
International Nuclear Information System (INIS)
Ayoub, N.Y.
1980-02-01
The ground and some excited O + (J=O, T=O positive parity) energy levels of closed-shell nuclei are examined, in an oscillator basis, using matrix techniques. The effect of states outside the mixed (O+2(h/2π)ω). model space in 4 He (namely configurations at 4(h/2π)ω excitation) are taken into account by renormalization using the generalized Rayleigh-Schroedinger perturbation expressions for a mixed multi-configurational model space, where the resultant non-symmetric energy matrices are diagonalized. It is shown that the second-order renormalized O + energy spectrum is close to the corresponding energy spectrum obtained by diagonalizing the O+2+4(h/2π)ω 4 He energy matrix. The effect, on the ground state and the first few low-lying excited O + energy levels, of renormalizing certain parts of the model space energy matrix up to second order in various approximations is also studied in 4 He and 16 O. It is found that the low-lying O + energy levels in these various approximations behave similarly in both 4 He and 16 O. (author)
Energy Technology Data Exchange (ETDEWEB)
Roussel, P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires
1968-05-01
We describe an experimental study of ({alpha},t), ({alpha},{sup 3}He) reactions at 44 MeV using a solid-state identifier, on the target-nuclei {sup 54}Fe and {sup 58,60,62,64}Ni. A critical study of optical model and of disturbed wave analysis has been performed. We show the complementarity of different transfer-reactions, the ambiguity of spectroscopic factors, the importance of the problem of the reaction mechanism. (author) [French] On decrit une etude experimentale des reactions ({alpha},t), ({alpha},{sup 3}He) a 44 MeV utilisant un systeme identificateur de particules sur les noyaux-cibles {sup 54}Fe et {sup 58,60,62,64}Ni. Une etude critique de modele optique et d'analyse en ondes deformees (D.W.B.A.) a ete entreprise. On montre la complementarite des differentes reactions de transfert, l'ambiguite des facteurs spectroscopiques, l'importance du probleme du mecanisme. (auteur)
Energy Technology Data Exchange (ETDEWEB)
Podolyak, Zs.; Steer, S.J.; Pietri, S.; Regan, P.H.; Brandau, C.; Catford, W.N.; Cullen, I.J.; Gelletly, W.; Jones, G.A.; Liu, Z.; Walker, P.M. [University of Surrey, Department of Physics, Guildford (United Kingdom); Gorska, M.; Gerl, J.; Wollersheim, H.J.; Grawe, H.; Becker, F.; Geissel, H.; Kelic, A.; Kojouharov, I.; Kurz, N.; Montes, F.; Prokopowicz, W.; Saito, T.; Schaffner, H.; Tashenov, S.; Werner-Malento, E. [GSI, Darmstadt (Germany); Rudolph, D.; Hoischen, R. [Lund University, Department of Physics, Lund (Sweden); Garnsworthy, A.B. [University of Surrey, Department of Physics, Guildford (United Kingdom); Yale University, WNSL, New Haven, CT (United States); Maier, K.H. [Institute of Nuclear Physics, Krakow (Poland); University of the West of Scotland, Dept. of Physics, Paisley (United Kingdom); Bednarczyk, P.; Grebosz, J. [GSI, Darmstadt (Germany); Institute of Nuclear Physics, Krakow (Poland); Caceres, L. [GSI, Darmstadt (Germany); Universidad Autonoma de Madrid, Dept. de Fisica Teorica, Madrid (Spain); Doornenbal, P. [GSI, Darmstadt (Germany); Universitaet zu Koeln, IKP, Koeln (Germany); Heinz, A. [Yale University, WNSL, New Haven, CT (United States); Kurtukian-Nieto, T. [Universidad de Santiago de Compostela, Santiago de Campostela (Spain); Benzoni, G.; Wieland, O. [Universita degli Studi di Milano (Italy); INFN, Milano (Italy); Pfuetzner, M. [Warsaw University, IEP, Warsaw (Poland); Jungclaus, A. [Universidad Autonoma de Madrid, Dept. de Fisica Teorica, Madrid (Spain); Balabanski, D.L. [Bulgarian Academy of Sciences, INRNE, Sofia (Bulgaria); Brown, B.A. [Univ. of Surrey, Dept. of Physics, Guildford (United Kingdom); Michigan State Univ., NSCL, East Lansing, MI (United States); Bruce, A.M.; Lalkovski, S. [Univ. of Brighton, School of Environment and Technology, Brighton (United Kingdom); Dombradi, Zs. [Institute for Nuclear Research, Debrecen (Hungary); Estevez, M.E. [Instituto de Fisica Corpuscular, Valencia (Spain)] [and others
2009-12-15
Heavy neutron-rich nuclei have been populated through the relativistic fragmentation of a {sup 208}{sub 82} Pb beam at E/A = 1 GeV on a 2.5 g/cm{sup 2} thick Be target. The synthesised nuclei were selected and identified in-flight using the fragment separator at GSI. Approximately 300 ns after production, the selected nuclei were implanted in an {proportional_to}8 mm thick perspex stopper, positioned at the centre of the RISING {gamma} -ray detector spectrometer array. A previously unreported isomer with a half-life T{sub 1/2} = 163(5) ns has been observed in the N=126 closed-shell nucleus {sup 205}{sub 79} Au. Through {gamma}-ray singles and {gamma}-{gamma} coincidence analysis a level scheme was established. The comparison with a shell model calculation tentatively identifies the spin-parity of the excited states, including the isomer itself, which is found to be I{sup {pi}} = (19/2{sup +}). (orig.)
International Nuclear Information System (INIS)
Yamamoto, Tohru; Akiyama, Masatsugu
1981-02-01
The decay data file for fission product nuclides (FP DECAY DATA FILE) has been prepared for summation calculation of the decay heat of fission products. The average energies released in β- and γ-transitions have been calculated with computer code PROFP. The calculated results and necessary information have been arranged in tabular form together with the estimated results for 470 nuclides of which decay data are not available experimentally. (author)
Collectivity in A ∼ 70 nuclei studied via lifetime measurements in 70 Br and 68,70 Se
Nichols, A.J.; Wadsworth, R.; Iwasaki, H.; Kaneko, K.; Lemasson, A.; de Angelis, G.; Bader, V.M.; Baugher, T.; Bazin, D.; Bentley, M.A.; Berryman, J.S.; Braunroth, T.; Davies, P.J.; Dewald, A.; Fransen, C.
2016-01-01
Transition strengths for decays from low-lying states in A ∼ 70 nuclei have been deduced from lifetime measurements using the recoil distance Doppler shift technique. The results confirm the collectivity previously reported for the 21+→0gs+ decay in 68 Se and reveal a relative decrease in collectivity in 70 Br. This trend is reproduced by shell model calculations using the GXPF1A interaction in an fp model space including the Coulomb, spin-orbit and isospin non-conserving interactions. The 31...
International Nuclear Information System (INIS)
Tombesi, F.; Cappi, M.; Dadina, M.; Reeves, J. N.; Palumbo, G. G. C.; Braito, V.
2011-01-01
X-ray absorption line spectroscopy has recently shown evidence for previously unknown Ultra-fast Outflows (UFOs) in radio-quiet active galactic nuclei (AGNs). These have been detected essentially through blueshifted Fe XXV/XXVI K-shell transitions. In the previous paper of this series we defined UFOs as those highly ionized absorbers with an outflow velocity higher than 10,000 km s –1 and assessed the statistical significance of the associated blueshifted absorption lines in a large sample of 42 local radio-quiet AGNs observed with XMM-Newton. The present paper is an extension of that work. First, we report a detailed curve of growth analysis of the main Fe XXV/XXVI transitions in photoionized plasmas. Then, we estimate an average spectral energy distribution for the sample sources and directly model the Fe K absorbers in the XMM-Newton spectra with the detailed Xstar photoionization code. We confirm that the frequency of sources in the radio-quiet sample showing UFOs is >35% and that the majority of the Fe K absorbers are indeed associated with UFOs. The outflow velocity distribution spans from ∼10,000 km s –1 (∼0.03c) up to ∼100,000 km s –1 (∼0.3c), with a peak and mean value of ∼42,000 km s –1 (∼0.14c). The ionization parameter is very high and in the range log ξ ∼ 3-6 erg s –1 cm, with a mean value of log ξ ∼ 4.2 erg s –1 cm. The associated column densities are also large, in the range N H ∼ 10 22 -10 24 cm –2 , with a mean value of N H ∼ 10 23 cm –2 . We discuss and estimate how selection effects, such as those related to the limited instrumental sensitivity at energies above 7 keV, may hamper the detection of even higher velocities and higher ionization absorbers. We argue that, overall, these results point to the presence of extremely ionized and possibly almost Compton-thick outflowing material in the innermost regions of AGNs. This also suggests that UFOs may potentially play a significant role in the expected
International Nuclear Information System (INIS)
Ognibene, T.J.
1996-03-01
To overcome the extreme difficulties encountered in the experimental decay studies of proton drip line nuclei, several techniques have been utilized, including a helium-jet transport system, particle identification detectors and mass separation. Improvements to the ion source/extraction region of the He-jet coupled on-line Recoil Atom Mass Analyzer (RAMA) and its target/ion source coupling resulted in significant increases in RAMA efficiencies and its mass resolution, as well as reductions in the overall transit time. At the 88-Inch Cyclotron at LBNL, the decays of 31 Cl, 27 P and 28 P, with half-lives of 150 msec, 260 msec and 270.3 msec, respectively, were examined using a he-jet and low-energy gas ΔE-gas ΔE-silicon E detector telescopes. Total beta-delayed proton branches of 0.3% and 0.07% in 31 Cl and 27 P, respectively, were estimated. Several proton peaks that had been previously assigned to the decay of 31 Cl were shown to be from the decay of 25 Si. In 27 P, two proton groups at 459 ± 14 keV and 610 ± 11 keV, with intensities of 7 ± 3% and 92 ± 4% relative to the main (100%) group were discovered. The Gamow-Teller component of the preceding beta-decay of each observed proton transition was compared to results from shell model calculations. Finally, a new proton transition was identified, following the β-decay of 28 P, at 1,444 ± 12 keV with a 1.7 ± 0.5% relative intensity to the 100% group. Using similar low-energy detector telescopes and the mass separator TISOL at TRIUMF, the 109 msec and 173 msec activities, 17 Ne and 33 Ar, were studied. A new proton group with energy 729 ± 15 keV was observed following the beta-decay of 17 Ne. Several discrepancies between earlier works as to the energies, intensities and assignments of several proton transitions from 17 Ne and 33 Ar were resolved
Spectroscopy of heavy fissionable nuclei
Indian Academy of Sciences (India)
2015-08-05
Aug 5, 2015 ... Nuclei in the actinide chain and beyond are prone to fission owing to ... mass nuclei are typically more difficult, because the intensity is .... j15/2 neutron alignments in a region where shell stablization effects are crucial.
Shell model and spectroscopic factors
International Nuclear Information System (INIS)
Poves, P.
2007-01-01
In these lectures, I introduce the notion of spectroscopic factor in the shell model context. A brief review is given of the present status of the large scale applications of the Interacting Shell Model. The spectroscopic factors and the spectroscopic strength are discussed for nuclei in the vicinity of magic closures and for deformed nuclei. (author)
Computer Security: Well fought, FP!
Stefan Lueders, Computer Security Team
2015-01-01
We are used to spam and phishing emails. But at the end of last year, a very special email struck one of our colleagues in the FP Department. An accountant was gently asked in an email from “Rolf.Heuer@cern.ch” to prepare a financial transaction - in the strictest confidence. A phone call from the beneficiary to the accountant was made in an attempt to support this request. Despite being instructed not to talk to anyone, the e-mail, the phone conversation and the circumstances were all so suspicious that our colleague consulted his hierarchy, the internal audit service and us. Well done, FP Department! This is a rare case of an attempt at “social engineering”, i.e. luring someone into doing something detrimental to the Organization. The e-mail was fake. While it appeared to come from “Rolf.Heuer@cern.ch”, it actually came from an alleged fraudster outside CERN. The e-mail and the phone call showed that he was well prepared and dire...
International Nuclear Information System (INIS)
Shimizu, Yoshifumi
2009-01-01
Except for the closed shell nuclei, almost all nuclei are in the superconducting state at their ground states. This well-known pair correlation in nuclei causes various interesting phenomena. It is especially to be noted that the pair correlation becomes weak in the excited states of nuclei with high angular momentum, which leads to the pair phase transition to the normal state in the high spin limit. On the other hand, the pair correlation becomes stronger in the nuclei with lower nucleon density than in those with normal density. In the region of neutron halo or skin state of unstable nuclei, this phenomenon is expected to be further enhanced to be observed compared to the ground state of stable nuclei. An overview of those interesting aspects caused via the pair correlation is presented here in the sections titled 'pair correlations in ground states', pair correlations in high spin states' and 'pair correlations in unstable nuclei' focusing on the high spin state. (S. Funahashi)
Shell model description of band structure in 48Cr
International Nuclear Information System (INIS)
Vargas, Carlos E.; Velazquez, Victor M.
2007-01-01
The band structure for normal and abnormal parity bands in 48Cr are described using the m-scheme shell model. In addition to full fp-shell, two particles in the 1d3/2 orbital are allowed in order to describe intruder states. The interaction includes fp-, sd- and mixed matrix elements
International Nuclear Information System (INIS)
Drukarev, E.G.; Trzhaskovskaya, M.B.
1989-01-01
We have calculated the contribution of the final state interaction to the ionization of the K-shell during the β - and β + decays. The contributions to the spectra of the β particles and to the total probability of the K shell ionization are obtained. The disagreement between the calculated values and the experimental data for the latter is shown to diminish strongly. The influence of the secondary electrons on the distribution is also determined. 27 refs.; 2 figs.; 2 tabs
Bibliometric performance analysis of publications from Danish researchers linked to FP6 and FP7
DEFF Research Database (Denmark)
Schneider, Jesper Wiborg; Ryan, Thomas Kjeldager
2015-01-01
This chapter presents an analysis29 of the impact of Danish scientific publications that were the result of FP6 or FP7 funding. The purpose is to gain an insight into the scientific impact researchers can achieve when participating in FP6 and FP7. In order to look at impact we have identified cit...... Foundation (DNRF) and the Danish Council for Independent Research (DFF). Finally the analyses also explore the impact at the level of programme themes under FP6 and FP7....
Inverted spin sequences in the spectra of odd-odd nuclei in the 2S-1d and 2P-1f shells
International Nuclear Information System (INIS)
Sharma, Arvind; Sharma, S.D.
1990-01-01
In case of odd-odd nuclei, near magic numbers, there are found inverted sequences as well as few rotational members. In order to explain the unique feature of the spectra of odd-odd nuclei, we have applied modified form of rotational-vibrational model with two parameters A and B. It is found that level orders in inverted as well as in rotational sequences are very well reproduced on the basis of this model. In case of inverted spin sequences, the sign of B is found to be positive. The ratio of B/A is ≅ 10 -2 as compared to its value of the order of 10 -3 in case of even-even and odd-A nuclei. We infer that pair correlations are responsible for these invertions. The simple model applied here worked well to predict these inverted spectra. (author)
International Nuclear Information System (INIS)
Scharff-Goldhaber, G.
1979-01-01
It was shown previously that, below a critical angular momentum, yrast bands of nonmagic 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. 17 references
Masses of new isotopes in the fp shell
International Nuclear Information System (INIS)
Davids, C.N.
1979-01-01
A total of four new neutron-rich isotopes were studied including 53 Ti, 57 Cr, 59 Mn, and 60 Mn. The bombardment of 58 Ni by various heavy ion beams resulted in the discovery of proton-rich 67 As and permitted extensive measurements of the superallowed decays of 62 Ge, 66 As, and 70 Br. 13 references
Czech Academy of Sciences Publication Activity Database
Khouaja, A.; Villari, A.; Baiborodin, Dmitri; Dlouhý, Zdeněk; Savajols, H.
2005-01-01
Roč. 25, - (2005), s. 223-226 ISSN 1434-6001 R&D Projects: GA ČR GA202/04/0791 Institutional research plan: CEZ:AV0Z1048901 Keywords : neutron-rich nuclei * deformation * isotopes Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 1.659, year: 2005
Energy Technology Data Exchange (ETDEWEB)
Perru, O
2004-12-01
For this thesis I have studied 2 neutron shell closures: N=40 and N=50. On N=50, an experiment was done in February 2001 on the ISOL line PARRNe, the issue was to measure the first excited states of {sup 83}Ge (Z=32, N=51) by studying the beta decay of {sup 83}Ga produced by fission of {sup 238}U.The extreme precision of the experimental device, with the operation of hot plasma ion sources made it possible to reach spectroscopic information of the Ge isotopes beyond the magic gap N=50. Two transitions have been attributed to {sup 83}Ge: at 867 keV and at 1238 keV. The level scheme of {sup 83}Ge could be interpreted in terms of weak coupling: the excited states of this nucleus are due to the couplings between the single neutron beyond N=50 and the remaining nucleons.On N=40, we wanted to determine the transition probability between ground state and first excited state, called B(E2), in {sup 70}Ni (N=42) and {sup 74}Zn (N=44) from Coulomb excitation. These exotic nuclei are produced by fragmentation of a primary beam of {sup 76}Ge on a target of {sup 58}Ni, selected by the spectrometer LISE, then interact with a secondary {sup 208}Pb target to induce the Coulomb excitation. At the end of this analysis, the following values have been obtained: B(E2,{sup 70}Ni)=860(170) e{sup 2}fm{sup 4}, B(E2,{sup 74}Zn)=1960(140) e{sup 2}fm{sup 4}. These values have been compared on the one hand to variational calculations which I have realised, on the other hand to published shell model calculations.These calculations point out the complex aspect of the Ni nuclei, which do not seem to have a typical behaviour of semi magic nuclei although they are located on a closed shell in protons (Z=28). (author)
International Nuclear Information System (INIS)
2001-01-01
The present collection of letters from JINR, Dubna, contains seven separate records on physics from extra dimensions, new physics in the new millennium with GENIUS: double beta decay, dark matter, solar neutrinos, the (μ - , e + ) conversion in nuclei mediated by light Majorana neutrinos, exotic muon-to-positron conversion in nuclei: partial transition sum evaluation by using shell model, solar neutrino problem accounting for self consistent magnetohydrodynamics solution for solar magnetic fields, first neutrino observations from the Sudbury neutrino observatory and status report on BOREXINO and results of the muon-background measurements at CERN
Gamow-Teller decay of T = 1 nuclei to odd-odd N = Z nuclei
Energy Technology Data Exchange (ETDEWEB)
Lisetskiy, A F [National Superconducting Cyclotron Laboratory, MSU, East Lansing, MI 48824 (United States); Gelberg, A [Institute for Nuclear Physics, University of Cologne, 50937 Cologne (Germany); Institute of Physical and Chemical Reasearch (RIKEN), Wako, 351-0198 (Japan); Brentano, P von [Institute for Nuclear Physics, University of Cologne, 50937 Cologne (Germany)
2005-01-01
Transition strengths of Gamow-Teller decay of T{sub z} = {+-}1 nuclei to N = Z odd-odd nuclei have been calculated in a two-nucleon approximation for spherical and deformed nuclei. The results obtained for the latter are quite close to the values obtained by full-space shell-model calculations and to the experiment.
Spectroscopy of 37Ar, 36Cl and the role of fp orbitals
International Nuclear Information System (INIS)
Ray, Sudatta; Ray, I.; Raut, R.; Pradhan, M.K.; Kanjilal, D.; Mukherjee, A.; Bhattacharya, S.; Banerjee, P.; Goswami, A.; Saha Sarkar, M.; Kshetri, Ritesh; Ganguly, S.; Ray Basu, M.; Ganguly, G.; Chakraborty, A.; Ghugre, S.S.; Krishichayan; Deo, A.; Kumar, S.; Jain, H.C.; Mazumdar, I.; Palit, R.; Sarkar, S.
2008-01-01
In the present work 36 Cl and 37 Ar have been studied using gamma spectroscopic techniques. Large basis cross-shell shell model calculations have been done to understand the role of the intruder orbitals in the structure of these nuclei
Masses of T/sub z/ = +5/2 nuclei in the s--d shell from β--decay measurements
International Nuclear Information System (INIS)
Alburger, D.E.; Goosman, D.R.; Davids, C.N.; Hardy, J.C.
1975-01-01
In this work the existence of five new T/sub z/ = + 5 / 2 nuclides, 23 F, 29 Mg, 31 Al, 33 Si, and 35 P, was established; their properties, including mass values, were determined, along with those of 25 Ne and 27 Na. Two experimental techniques were used, the ''rabbit'' transfer of a solid target and the gas transfer system; some novel features of these are described. A β spectrum of 33 Si observed in coincidence with 1848-keV γ rays is shown; a mass excess of -20569 +- 50 keV was derived for 33 Si. Attempts to produce 21 O were unsuccessful. Comparisons of the measured masses of the T/sub z/ = + 5 / 2 nuclides in the 2s--1d shell with predictions of the Garvey--Kelson mass formulation and with shell-model calculations are shown. The latter produce considerably better agreement with experiment. (3 figures, 1 table) (U.S.)
International Nuclear Information System (INIS)
Afnan, I.R.; Thomas, A.W.
1976-01-01
A method has been suggested for relating μ-capture in nuclei to pion absorption through partially conserved axial vector current hypothesis. The success of the method relies heavily on the knowledge of the pion absorption amplitude at a momentum transfer equal to the μ-meson mass. That is we need to know the pion absorption amplitude off the mass-shell. The simplest nucleus for which this suggestion can be examined is μ-capture in deuterium. The Koltum-Reitan model is used to determine the pion absorption amplitude off the mass shell. In particular the senstivity of this off-mass-shell extrapolution to details of the N-N interaction is studied. (author)
Energy Technology Data Exchange (ETDEWEB)
Suzuki, Toshio [Department of Physics and Graduate School of Integrated Basic Sciences, College of Humanities and Sciences, Nihon University Sakurajosui 3-25-40, Setagaya-ku, Tokyo 156-8550 (Japan); Toki, Hiroshi [Research Center for Nuclear Physics (RCNP), Osaka University, Ibaraki, Osaka 567-0047 (Japan); Nomoto, Ken’ichi, E-mail: suzuki@phys.chs.nihon-u.ac.jp [Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo, Kashiwa, Chiba 277-8583 (Japan)
2016-02-01
Electron-capture and β-decay rates for nuclear pairs in the sd-shell are evaluated at high densities and high temperatures relevant to the final evolution of electron-degenerate O–Ne–Mg cores of stars with initial masses of 8–10 M{sub ⊙}. Electron capture induces a rapid contraction of the electron-degenerate O–Ne–Mg core. The outcome of rapid contraction depends on the evolutionary changes in the central density and temperature, which are determined by the competing processes of contraction, cooling, and heating. The fate of the stars is determined by these competitions, whether they end up with electron-capture supernovae or Fe core-collapse supernovae. Since the competing processes are induced by electron capture and β-decay, the accurate weak rates are crucially important. The rates are obtained for pairs with A = 20, 23, 24, 25, and 27 by shell-model calculations in the sd-shell with the USDB Hamiltonian. Effects of Coulomb corrections on the rates are evaluated. The rates for pairs with A = 23 and 25 are important for nuclear Urca processes that determine the cooling rate of the O–Ne–Mg core, while those for pairs with A = 20 and 24 are important for the core contraction and heat generation rates in the core. We provide these nuclear rates at stellar environments in tables with fine enough meshes at various densities and temperatures for studies of astrophysical processes sensitive to the rates. In particular, the accurate rate tables are crucially important for the final fates of not only O–Ne–Mg cores but also a wider range of stars, such as C–O cores of lower-mass stars.
International Nuclear Information System (INIS)
Suzuki, Toshio; Toki, Hiroshi; Nomoto, Ken’ichi
2016-01-01
Electron-capture and β-decay rates for nuclear pairs in the sd-shell are evaluated at high densities and high temperatures relevant to the final evolution of electron-degenerate O–Ne–Mg cores of stars with initial masses of 8–10 M ⊙ . Electron capture induces a rapid contraction of the electron-degenerate O–Ne–Mg core. The outcome of rapid contraction depends on the evolutionary changes in the central density and temperature, which are determined by the competing processes of contraction, cooling, and heating. The fate of the stars is determined by these competitions, whether they end up with electron-capture supernovae or Fe core-collapse supernovae. Since the competing processes are induced by electron capture and β-decay, the accurate weak rates are crucially important. The rates are obtained for pairs with A = 20, 23, 24, 25, and 27 by shell-model calculations in the sd-shell with the USDB Hamiltonian. Effects of Coulomb corrections on the rates are evaluated. The rates for pairs with A = 23 and 25 are important for nuclear Urca processes that determine the cooling rate of the O–Ne–Mg core, while those for pairs with A = 20 and 24 are important for the core contraction and heat generation rates in the core. We provide these nuclear rates at stellar environments in tables with fine enough meshes at various densities and temperatures for studies of astrophysical processes sensitive to the rates. In particular, the accurate rate tables are crucially important for the final fates of not only O–Ne–Mg cores but also a wider range of stars, such as C–O cores of lower-mass stars
Spin-isospin excitation in sd-shell nuclei studied by the (d,2He) reaction at Ed=270MeV
International Nuclear Information System (INIS)
Niizeki, T.; Ohnuma, H.; Yamamoto, T.; Katoh, K.; Yamashita, T.; Hara, Y.; Okamura, H.; Sakai, H.; Ishida, S.; Sakamoto, N.; Otsu, H.; Wakasa, T.; Uesaka, T.; Satou, Y.; Fujita, T.; Ichihara, T.; Orihara, H.; Toyokawa, H.; Hatanaka, K.; Kato, S.; Kubono, S.; Yosoi, M.
1994-01-01
The (d, 2 He) reactions on 24 Mg, 26 Mg and 28 Si were studied at E d =270MeV. The 0 cross sections obtained for the 1 + states from the 24 Mg, 28 Si(d, 2 He) reactions show a good correlation with those from the mirror (p,n) reactions. Four peaks were identified in the 26 Mg(d, 2 He) 26 Ne reaction as being due to the 1 + excitation. The B(GT + ) values for these transitions were estimated and compared with the shell model prediction. ((orig.))
Energy Technology Data Exchange (ETDEWEB)
Courtin, S.; Baumann, P.; Dessagne, Ph.; Marechal, F.; Miehe, Ch.; Perrot, F.; Poirier, E.; Ramdhane, M. [Institut de Recherches Subatomiques, Strasbourg Cedex 2 (France); ISOLDE collaboration
2004-09-15
This paper describes two beta decay experiments performed at the CERN/ISOLDE mass separator. The structure of {sup 74}Kr has been studied using a total absorption {gamma} spectrometer (TAgS). The measured Gamow-Teller strength is presented and compared to HFBCS+QRPA calculations. The {sup 33}Na decay is also presented. The structure of the {sup 33}Mg daughter nucleus is compared to shell-model calculations, showing for the first time an inversion of states in the A{sub {approx}}35 mass region. (author)
Perspectives of production of superheavy nuclei
Energy Technology Data Exchange (ETDEWEB)
Adamian, G. G.; Antonenko, N. V., E-mail: antonenk@theor.jinr.ru; Bezbakh, A. N.; Sargsyan, V. V. [Joint Institute for Nuclear Research, RU–141980 Dubna (Russian Federation); Scheid, W. [Institut für Theoretische Physik der Justus-Liebig-Universität, D–35392 Giessen (Germany)
2016-07-07
Possible ways of production of superheavies are discussed. Impact of nuclear structure on the production of superheavy nuclei in complete fusion reactions is discussed. The proton shell closure at Z = 120 is discussed.
Superheavy nuclei: a relativistic mean field outlook
International Nuclear Information System (INIS)
Afanasjev, A.V.
2006-01-01
The analysis of quasi-particle spectra in the heaviest A∼250 nuclei with spectroscopic data provides an additional constraint for the choice of effective interaction for the description of superheavy nuclei. It strongly suggests that only the parametrizations which predict Z = 120 and N = 172 as shell closures are reliable for superheavy nuclei within the relativistic mean field theory. The influence of the central depression in the density distribution of spherical superheavy nuclei on the shell structure is studied. A large central depression produces large shell gaps at Z = 120 and N = 172. The shell gaps at Z = 126 and N = 184 are favoured by a flat density distribution in the central part of the nucleus. It is shown that approximate particle number projection (PNP) by means of the Lipkin-Nogami (LN) method removes pairing collapse seen at these gaps in the calculations without PNP
International Nuclear Information System (INIS)
Villari, A.C.C.
1990-01-01
The actual tendencies to study exotic nuclei; applications of exotic nuclei beams in material study and medicine; recent results obtained by GANIL and Berkeley Laboratories of measurements of binding energy and radii of light nuclei; the future experiences to be carry out in several international laboratories and; proposal of studies in Brazil using Pelletron-USP accelerator and the LINAC superconductor accelerator, in construction in the same laboratory, are presented. (M.C.K.)
Energy Technology Data Exchange (ETDEWEB)
Bruge, G [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires
1967-01-01
This report gives the results from a systematic study by 44 MeV {alpha} particle scattering on the collective states of closed shell nuclei with 28 neutrons, 28 and 50 protons especially in the energy region corresponding to the two phonon vibrational triplet. The nuclei studied are: {sup 46}Ti, {sup 48}Ti, {sup 50}Ti, {sup 52}Cr, {sup 54}Fe, {sup 56}Fe, {sup 58}Fe, {sup 58}Ni, {sup 60}Ni, {sup 62}Ni, {sup 64}Ni, {sup 112}Sn, {sup 114}Sn, {sup 116}Sn, {sup 118}Sn, {sup 120}Sn, {sup 122}Sn and {sup 124}Sn. The theoretical analysis has been made with the Austern and Blair model using a phase shift analysis of the elastic scattering. Deformation lengths {delta}{sub I} = {beta}{sub I}R and transition probabilities obtained are compared with several experimental and theoretical data. (author) [French] Ce rapport donne les resultats d'une etude systematique par diffusion de particules {alpha} de 44 MeV des etats collectifs des noyaux au voisinage des couches fermees a 28 neutrons et 28 et 50 protons, specialement dans la region correspondant au triplet vibrationnel a deux phonons. Les noyaux etudies sont: {sup 46}Ti, {sup 48}Ti, {sup 50}Ti, {sup 52}Cr, {sup 54}Fe, {sup 56}Fe, {sup 58}Fe, {sup 58}Ni, {sup 60}Ni, {sup 62}Ni, {sup 64}Ni, {sup 112}Sn, {sup 114}Sn, {sup 116}Sn, {sup 118}Sn, {sup 120}Sn, {sup 122}Sn et {sup 124}Sn. L'analyse theorique a ete faite a l'aide du modele de Austern et Blair utilisant une analyse en dephasages de la diffusion elastique. Les longueurs de deformation {delta}I = {beta}{sub I}R obtenues pour chaque niveau sont comparees a plusieurs donnees experimentales et theoriques. (auteur)
Single Particle Entropy in Heated Nuclei
International Nuclear Information System (INIS)
Guttormsen, M.; Chankova, R.; Hjorth-Jensen, M.; Rekstad, J.; Siem, S.; Sunde, A. C.; Syed, N. U. H.; Agvaanluvsan, U.; Schiller, A.; Voinov, A.
2006-01-01
The thermal motion of single particles represents the largest contribution to level density (or entropy) in atomic nuclei. The concept of single particle entropy is presented and shown to be an approximate extensive (additive) quantity for mid-shell nuclei. A few applications of single particle entropy are demonstrated
Laser method of free atom nuclei orientation
International Nuclear Information System (INIS)
Barabanov, A.L.
1987-01-01
Orientation process of free atom (atoms in beams) nuclei, scattering quanta of circularly polarized laser radiation is considered. A method for the evaluation of nuclei orientation parameters is developed. It is shown that in the process of pumping between the ground and first excited atomic states with electron shell spins J 1 and J 2 , so that J 2 = J 1 + 1, a complete orientation of nuclei can be attained
International Nuclear Information System (INIS)
Hamilton, J.H.
1987-01-01
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 185 Au, and competing triaxial and prolate shapes in 71 Se and 176 Pt. 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 152 Dy, 132 Ce and 135 Nd. 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, 68 Ge and 70 Se. The differences are thought to be related to the competing shell gaps in these nuclei
2007-01-01
The evolution of the unknown ground-state ${\\beta}$-decay properties of the neutron-rich $^{84-89}$Ge, $^{90-93}$Se and $^{102-104}$Sr isotopes near the r-process path is of high interest for the study of the abundance peaks around the N=50 and N=82 neutron shells. At ISOLDE, beams of certain elements with sufficient isotopic purity are produced as molecular sidebands rather than atomic beams. This applies e.g, to germanium, separated as GeS$^{+}$, selenium separated as SeCO$^{+}$ and strontium separated as SrF$^{+}$. However, in case of neutron-rich isotopes produced in actinide targets, new "isobaric" background of atomic ions appears on the mass of the molecular sideband. For this particular case, the ECR charge breeder, positioned in the experimental hall after ISOLDE first mass separation, can be advantageously used as a purification device, by breaking the molecules and removing the molecular contaminants. This proposal indicates our interest in the study of basic nuclear structure properties of neutron...
International Nuclear Information System (INIS)
Oyamatsu, K.; Yamada, M.
1994-01-01
We report on the recent progress in understanding the matter in the crust of a neutron star. For nuclides in the outer crust, recently measured masses of neutron-rich nuclei enable us to determine more accurately the stable nuclide as a function of the matter density. In the inner crust, the compressible liquid-drop model predicts successive change of the nuclear shape, from sphere to cylinder, slab, cylindrical hole and spherical hole at densities just before the transition to uniform matter. In order to go beyond the liquiddrop model, we performed the Thomas-Fermi calculation paying special attention to the surface diffuseness, and have recently calculated the shell energies of the non-spherical nuclei. We have found from these studies that all these non-spherical nuclei exist stably in the above order even if we include the surface diffuseness and shell energies. (author)
Women's development key to MCH/FP.
1991-05-01
The Sri Lankan government has included women in its development process thereby raising literacy levels to 91% for urban women and 87% for rural women. Their successful participation has in turn resulted in improvements in maternal and child health (MCH) and family planning (FP) acceptance. Indeed MCH/FP promotion could not have occurred without their participation in development. Since the 1960s, the Health and Women's Affairs Ministry continues to provide broad support for grass roots health care, such as strengthening the capacity of local clinics to increase coverage of health monitoring for women and children. There fore infant mortality in Sri Lanka has decreased from 47.5 in 1970 to 34 in 1980 to 19 in 1989. In addition, the total fertility rate fell from 5 in 1962-1964 to 3.4 in 1980-1982 to 2.8 in 1982-1987. The Ministry initiated its Integrated FP, Nutrition, and Parasite Control Project (IP) in 8 pilot areas in 1981. IP continues to encourage women's developed and MCH/FP at the grass roots level. In fact, FP acceptance rates increased from 31.8% in 1980 to 59% in 1989 in Nakulugamuwa and from 2.3% in 1980 to 70.5% in 1989 in Galnewa. The MCH component operating from community level clinics includes growth monitoring and immunization. Project activities include construction of latrines and wells, promotion of regular health examinations for mothers and children, FP education, counseling, nutrition promotion for children, and training programs for health staff, community volunteers, mothers' groups, and teachers. The volunteers form a link between the community and government health workers. Mothers' groups participate in school nutrition programs, home gardening, and income generation. Parasite control is consequently accomplished by community health and environmental sanitation promotion.
Exotic Nuclei and Yukawa's Forces
International Nuclear Information System (INIS)
Otsuka, Takaharu; Suzuki, Toshio; Utsuno, Yutaka
2008-01-01
In this plenary talk, we will overview the evolution of the shell structure in stable and exotic nuclei as a new paradigm of nuclear structure physics. This shell evolution is primarily due to the tensor force. The robust mechanism and some examples will be presented. Such examples include the disappearance of existing magic numbers and the appearance of new ones. The nuclear magic numbers have been believed, since Mayer and Jensen, to be constants as 2, 8, 20, 28, 50, ... This turned out to be changed, once we entered the regime of exotic nuclei. This shell evolution develops at many places on the nuclear chart in various forms. For example, superheavy magic numbers may be altered. Thus, we are led to a new paradigm as to how and where the nuclear shell evolves, and what consequences arise. The evolution of the shell affects weak process transitions, and plays a crucial role in deformation. The π and ρ mesons generate tensor forces, and are the fundamental elements of such intriguing phenomena. Thus, physics of exotic nuclei arises as a manifestation of Yukawa's forces
Energy Technology Data Exchange (ETDEWEB)
Marchix, A
2007-11-15
The aim of this work is to study the influence of shell correction energy on the deexcitation of superheavy nuclei. For that purpose, a new statistical code, called Kewpie2, which is based on an original algorithm allowing to have access to very weak probabilities, was developed. The results obtained with Kewpie2 have been compared to the experimental data on residue cross sections obtained by cold fusion (Z=108 to Z=113) and by hot fusion (Z=112, Z=114 and Z=116), as well as data on fission times (Z=114, Z=120 and Z=126). Constraints on the microscopic structure of the studied nuclei have been obtained by means of the shell correction energy. By adjusting the intrinsic parameters of the models of fusion in order to reproduce the data on the fusion cross sections, this study shows the necessity of decreasing very strongly the shell correction energy predicted by the calculations of Moller and Nix, during the study of the residues cross sections as well for the nuclei produced by cold fusion as by hot fusion. On the other hand, during the confrontation of the results of Kewpie2 to the data on mean fission times, it is rather advisable to increase it. A shift of the proton shell closure predicted for Z=114 by the calculations of Moller and Nix towards larger Z would allow to explain these opposite conclusions. In this thesis, we also have shown the significant influence of the inclusion of isomeric states on fission times for the superheavy nuclei. (author)
The Role of Broken Cooper Pairs in Warm Nuclei
International Nuclear Information System (INIS)
Guttormsen, M.; Chankova, R.; Larsen, A.C.; Rekstad, J.; Siem, S.; Syed, N.U.H.; Agvaanluvsan, U.; Schiller, A.; Voinov, A.
2007-01-01
In order to understand warm nuclei and describe the underlying microscopic structure, entropy is measured for several even-even and odd-mass nuclei. Mid-shell nuclei show significant odd-even entropy differences interpreted as the single-particle entropy introduced by the valence nucleon. A method to extract critical temperatures for the pair breaking process is demonstrated. (author)
MAGIC NUCLEI: Tin-100 turns up
International Nuclear Information System (INIS)
Anon.
1994-01-01
In the same way as the Periodic Table of chemical elements reflects the successive filling of orbital electron shells, in nuclear physics the socalled 'magic' numbers correspond to closed shells of 2, 8, 20, 28, 50, 82, 126,... neutrons and/or protons. More tightly bound than other nuclei, these are the nuclear analogues of the inert gases. 'Doubly magic' nuclei have closed shells of both neutrons and protons. Examples in nature are helium-4 (2 protons and 2 neutrons), oxygen-16 (8 and 8), calcium-40 (20 and 20) and calcium-48 (20 and 28). Radioactive tin-132 (50+82) has been widely studied
Hadronic interaction and structure of exotic nuclei
International Nuclear Information System (INIS)
Otsuka, Takaharu
2009-01-01
I will overview recent studies on the evolution of the shell structure in stable and exotic nuclei, and will show its relevance to hadronic interaction, including nuclear forces. This shell evolution is primarily due to the tensor force. The robust mechanism and some examples will be presented. Such examples include the disappearance of existing magic numbers and the appearance of new ones. The shell structure and existing limit of nuclei depend also on the three-body interaction in a specific way. I will sketch how the Δ-hole excitation induced three-body force (Fujita-Miyazawa force) modifies them. (author)
Determination of shell energies. Nuclear deformations and fission barriers
International Nuclear Information System (INIS)
Koura, Hiroyuki; Tachibana, Takahiro; Uno, Masahiro; Yamada, Masami.
1996-01-01
We have been studying a method of determining nuclear shell energies and incorporating them into a mass formula. The main feature of this method lies in estimating shell energies of deformed nuclei from spherical shell energies. We adopt three assumptions, from which the shell energy of a deformed nucleus is deduced to be a weighted sum of spherical shell energies of its neighboring nuclei. This shell energy should be called intrinsic shell energy since the average deformation energy also acts as an effective shell energy. The ground-state shell energy of a deformed nucleus and its equilibrium shape can be obtained by minimizing the sum of these two energies with respect to variation of deformation parameters. In addition, we investigate the existence of fission isomers for heavy nuclei with use of the obtained shell energies. (author)
Present status and plans of JENDL FP data evaluation project
International Nuclear Information System (INIS)
Kawano, Toshihiko
2003-01-01
The Fission Product (FP) data evaluation is one of the key issues for the next revision of JENDL, since many data were carried over from JENDL-3.2 to 3.3. The new FP Working Group (FPWG) was organized in the Japanese Nuclear Data Committee (JNDC) to perform new evaluations of FP data for JENDL. In the present review of FP data evaluation, we show the history and current status of FP nuclear data, requirements of FP data, new measurements, the international cooperation, and the future plans toward the new JENDL. (author)
International Nuclear Information System (INIS)
De Wit, P.; Looijesteijn, B.; Regeer, B.; Stip, B.
1995-03-01
In the bi-monthly issues of 'Shell Venster' (window on Shell) attention is paid to the activities of the multinational petroleum company Shell Nederland and the Koninklijke/Shell Groep by means of non-specialist articles
Investigation of copper nuclei
International Nuclear Information System (INIS)
Delfini, M.G.
1983-01-01
An extensive study has been performed on copper isotopes in the mass region A=63-66. The results of a precise measurement are presented on the properties of levels of 64 Cu and 66 Cu. They were obtained by bombarding the 63 Cu and 65 Cu nuclei with neutrons. The gamma spectra collected after capture of thermal, 2-keV, 24-keV neutrons have been analysed and combined to give a rather extensive set of precise level energies and gamma transition strengths. From the angular distribution of the gamma rays it is possible to obtain information concerning the angular momentum J of several low-lying states. The level schemes derived from such measurements have been used as a test for calculations in the framework of the shell model. The spectral distributions of eigenstates in 64 Cu for different configuration spaces are presented and discussed. In this study the relative importance of configurations with n holes in the 1f7/2 shell with n up to 16, are investigated. It is found that the results strongly depend on the values of the single-particle energies. The results of the spectral-distribution method were utilized for shell-model calculations. From the information obtained from the spectral analysis it was decided to adopt a configuration space which includes up to one hole in the 1f7/2 shell and up to two particles in the 1g9/2 shell. Further, restrictions on seniority and on the coupling of the two particles in the 1g9/2 orbit have been applied and their effects have been studied. It is found that the calculated excitation energies reproduce the measured values in a satisfactory way, but that some of the electromagnetic properties are less well in agreement with experimental data. (Auth.)
Exotic nuclei: another aspect of nuclear structure
International Nuclear Information System (INIS)
Dobaczewski, J.; Blumenfeld, Y.; Flocard, H.; Garcia Borge, M.J.; Nowacki, F.; Rombouts, S.; Theisen, Ch.; Marques, F.M.; Lacroix, D.; Dessagne, P.; Gaeggeler, H.
2002-01-01
This document gathers the lectures made at the Joliot Curie international summer school in 2002 whose theme that year was exotic nuclei. There were 11 contributions whose titles are: 1) interactions, symmetry breaking and effective fields from quarks to nuclei; 2) status and perspectives for the study of exotic nuclei: experimental aspects; 3) the pairing interaction and the N = Z nuclei; 4) borders of stability region and exotic decays; 5) shell structure of nuclei: from stability to decay; 6) variational approach of system with a few nucleons; 7) from heavy to super-heavy nuclei; 8) halos, molecules and multi-neutrons; 9) macroscopic approaches for fusion reactions; 10) beta decay: a tool for spectroscopy; 11) the gas phase chemistry of super-heavy elements
International Nuclear Information System (INIS)
Janssens, R.V.F.; Khoo, T.L.
1991-01-01
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 152 Dy (8). At about the same time, evidence for highly deformed nuclei (axis ratio 3:2) was also reported near 132 Ce(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
From heavy nuclei to super-heavy nuclei
International Nuclear Information System (INIS)
Theisen, Ch.
2003-01-01
The existence of super-heavy nuclei has been predicted nearly fifty years ago. Due to the strong coulomb repulsion, the stabilisation of these nuclei is possible only through shell effects. The reasons for this fragile stability, as well as the theoretical predictions concerning the position of the island of stability are presented in the first part of this lecture. In the second part, experiments and experimental techniques which have been used to synthesize or search for super-heavy elements are described. Spectroscopic studies performed in very heavy elements are presented in the following section. We close this lecture with techniques that are currently being developed in order to reach the superheavy island and to study the structure of very-heavy nuclei. (author)
Collectivity in A ∼ 70 nuclei studied via lifetime measurements in {sup 70}Br and {sup 68,70}Se
Energy Technology Data Exchange (ETDEWEB)
Nichols, A.J., E-mail: an527@york.ac.uk [Department of Physics, University of York, Heslington, York YO10 5DD (United Kingdom); Wadsworth, R. [Department of Physics, University of York, Heslington, York YO10 5DD (United Kingdom); Iwasaki, H. [National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University, 164 S. Shaw Lane, East Lansing, MI 48825-1321 (United States); Kaneko, K. [Department of Physics, Kyushu Sangyo University, Fukuoka 813-8503 (Japan); Lemasson, A. [National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University, 164 S. Shaw Lane, East Lansing, MI 48825-1321 (United States); Grand Accélérateur National d' Ions Lourds, Bd. Henri Becquerel, BP 55027, F-14076 Caen Cedex 05 (France); Angelis, G. de [Laboratori Nazionali di Legnaro dell' INFN, Legnaro (Padova) I-35020 (Italy); Bader, V.M.; Baugher, T.; Bazin, D. [National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University, 164 S. Shaw Lane, East Lansing, MI 48825-1321 (United States); Bentley, M.A. [Department of Physics, University of York, Heslington, York YO10 5DD (United Kingdom); Berryman, J.S. [National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University, 164 S. Shaw Lane, East Lansing, MI 48825-1321 (United States); Braunroth, T. [Institut für Kernphysik der Universität zu Köln, Köln 50937 (Germany); Davies, P.J. [Department of Physics, University of York, Heslington, York YO10 5DD (United Kingdom); and others
2014-06-02
Transition strengths for decays from low-lying states in A ∼ 70 nuclei have been deduced from lifetime measurements using the recoil distance Doppler shift technique. The results confirm the collectivity previously reported for the 2{sub 1}{sup +}→0{sub gs}{sup +} decay in {sup 68}Se and reveal a relative decrease in collectivity in {sup 70}Br. This trend is reproduced by shell model calculations using the GXPF1A interaction in an fp model space including the Coulomb, spin-orbit and isospin non-conserving interactions. The 3{sub 1}{sup +}→2{sub 1}{sup +} decay in {sup 70}Br is found to have a very small B(M1) value, which is consistent with the configuration of the state being dominated by the coupling of f{sub 5/2} protons and neutrons. The results suggest that the g{sub 9/2} orbit does not play an important role at low spin in these nuclei. The B(E2) values for the decays of the (T = 1) 2{sub 1}{sup +} states in {sup 70}Br and {sup 70}Se are almost identical, suggesting there is no major shape change between the two nuclei at low spin.
Hyperdeformed nuclei and the residual pseudo-SU(3) symmetry
International Nuclear Information System (INIS)
Dudek, J.; Werner, T.
1988-01-01
The author discusses superdeformed and hypothetical hyperdeformed nuclei. Quadrupole deformations characteristic of these types of nuclei are defined. Symmetry features are also discussed. The characteristic cycle dependence of shell structures as functions of the deformation gives rise to chains of the deformed shell closures. Such a chain structure applies to moderately-, super- and hyper-deformed nuclei as well. The resulting total energy calculations give a systematic variation of super- and hyperdeformations with, e.g., increasing N at fixed Z, thus predicting the way nuclei deviate from the simple a:b = 2:1 and a:b = 3:1 symmetries
Resonances in s-d shell nuclei
International Nuclear Information System (INIS)
Schiffer, J.P.
1981-01-01
It appears that the system we have studied here, 24 Mg( 16 O, 12 C) 28 Si representing 40 Ca as the composite nucleus, is perhaps the heaviest one that exhibits strong enough resonances that quantitative measurements may be contemplated. But we have uncovered only a small corner of what is there and even within this system a huge amount of work remains. The nature of these resonances is not yet clear. The sequence may perhaps have an explanation that is schematically outlined, namely that there are several families of quasistationary states in 40 Ca, but that the slopes of these families do not necessarily coincide with the slope of the grazing partial waves that provide us with a narrow transparent strip of a window on the underlying structure of the nucleus. We must concentrate a lot of effort and ingenuity in order to maximize the information we gather through this window and only then may we hope to sensibly attempt forming hypotheses about the underlying simple pattern
Electric monopole transitions from low energy excitations in nuclei
Wood, J L; De Coster, C; Heyde, Kris L G
1999-01-01
Electric monopole (E0) properties are studied across the entire nuclear mass surface. Besides an introductory discussion of various model results (shell model, geometric vibrational and rotational models, algebraic models), we point out that many of the largest E0 transition strengths, $\\rho^2$(E0), are associated with shape mixing. We discuss in detail the manifestation of E0 transitions and present extensive data for~: single-closed shell nuclei, vibrational nuclei, well-deformed nuclei, nuclei that exhibit sudden ground-state changes, and nuclei that exhibit shape coexistence and intruder states. We also give attention to light nuclei, odd-A nuclei, and illustrate a suggested relation between $\\rho^2$(E0) and isotopic shifts.
International Nuclear Information System (INIS)
Balian, Roger; Remaud, Bernard; Suraud, E.; Durand, Dominique; Tamain, Bernard; Gobbi, A.; Cugnon, J.; Drapier, Olivier; Govaerts, Jan; Prieels, Rene
1995-09-01
This 14. international school Joliot-Curie of nuclear physic deals with nuclei in collision at high energy. Nine lectures are included in the proceedings of this summer school: 1 - From statistical mechanics outside equilibrium to transport equations (Balian, R.); 2 - Modeling of heavy ions reactions (Remaud, B.); 3 - Kinetic equations in heavy ions physics (Suraud, E.); 4 - Colliding nuclei near the Fermi energy (Durand, D.; Tamain, B.); 5 - From the Fermi to the relativistic energy domain: which observable? For which physics? (Gobbi, A.); 6 - Collisions at relativistic and ultra relativistic energies, Theoretical aspects (Cugnon, J.); 7 - Quark-gluon plasma: experimental signatures (Drapier, O.); 8 - Electroweak interaction: a window on physics beyond the standard model (Govaerts, J.); 9 - Symmetry tests in β nuclear process: polarization techniques (Prieels, R.)
Electro-magnetic properties of heavy nuclei
International Nuclear Information System (INIS)
Otsuka, Takaharu
1989-01-01
Two topics of electro-magnetic properties of heavy nuclei are discussed. The first topic is the M1 excitation from well-deformed heavy nuclei, and the other is the sudden increase of the isotope shift as a function of N in going away from the closed shell. These problems are considered in terms of the particle-number projected (Nilsson-) BCS calculation. (author)
Energy Technology Data Exchange (ETDEWEB)
Bastin, B
2007-10-15
For a few years now, a loss of magicity in neutron-rich nuclei near the neutron drip-line at N=28 has been suggested and observed. Deformation in these nuclei has been observed. The deformation was explained in S isotopes as being due to a moderate reduction of the N=28 shell closure together with a proton induced collectivity originating from the near degeneracy of the proton d3/2 and s1/2 orbitals. As a consequence, the observed deformation seems to result from a subtle interplay between neutron and proton excitations. Since the proton configuration in the Si isotopes is expected to be more stable due to the Z=14 sub-shell gap, {sup 42}Si was considered as a key nucleus in order to distinguish the different effects responsible for the structural changes observed at N=28. Even if it is at the limits of our technical possibilities, an in-beam gamma-spectroscopy experiment using two-step fragmentation and one or several nucleons knockout reaction mechanisms was performed at GANIL. The measurement of the energy of the first excited state in {sup 42}Si, combined with the observation of {sup 38,40}Si and the spectroscopy of {sup 41,43}P, has given evidence for the loss of magicity at N=28 far from stability. Modifications of the effective interaction used in modern shell model calculations have been completed following this investigation, increasing its predictive character. This study confirms the role of the tensor force and the density dependence of the spin-orbit interaction in the collapse of the N=28 shell closure. (author)
Perturbative many-body approaches to finite nuclei
International Nuclear Information System (INIS)
Hjort-Jensen, M.; Engeland, T.; Holt, A.; Osnes, E.
1992-06-01
In this work the authors discuss various approaches to the effective interaction appropriate for finite nuclei. The methods reviewed are the folded-diagram method of Kuo and co-workers and the summation of the folded diagrams as advocated by Lee and Suzuki. Examples of applications to sd-shell nuclei from previous works are discussed together with hitherto unpublished results for nuclei in pf-shell. Since the method of Lee and Suzuki is found to yield the best converged results, this method is applied to calculate the effective interaction for nuclei in the pf-shell. For the calculation of the effective interaction, three recent versions of the Bonn meson-exchange potential model have been used. These versions are fitted to the same set of data and differ only in the strength of the tensor force. The importance of the latter for finite nuclei is discussed. 67 refs., 17 figs., 7 tabs
Neutron rich nuclei around 132Sn
International Nuclear Information System (INIS)
Bhattacharya, Sarmishtha
2016-01-01
The neutron rich nuclei with few particles or holes in 132 Sn have various experimental and theoretical interest to understand the evolution of nuclear structure around the doubly magic shell closure Z=50 and N=82. Some of the exotic neutron rich nuclei in this mass region are situated near waiting points in the r-process path and are of special astrophysical interest. Neutron rich nuclei near 132 Sn have been studied using fission fragment spectroscopy. The lifetime of low lying isomeric states have been precisely measured and the beta decay from the ground and isomeric states have been characterized using gamma-ray spectroscopy
Is there chirality in atomic nuclei?
International Nuclear Information System (INIS)
Meng Jie
2009-01-01
Static chiral symmetries are common in nature, for example, the macroscopic spirals of snail shells, the microscopic handedness of certain molecules, and human hands. The concept of chirality in atomic nuclei was first proposed in 1997, and since then many efforts have been made to understand chiral symmetry and its spontaneous breaking in atomic nuclei. Recent theoretical and experimental progress in the verification of chirality in atomic nuclei will be reviewed, together with a discussion of the problems that await to be solved in the future. (authors)
International Nuclear Information System (INIS)
Nosov, V.G.; Kamchatnov, A.M.
A consistent theory of the shell and magic oscillations of the masses of spherical nuclei is developed on the basis of the Fermi liquid concept of the energy spectrum of nuclear matter. A ''magic'' relationship between the system's dimensions and the limiting momentum of the quasi-particle distribution is derived; an integer number of the de Broglie half-waves falls on the nuclear diameter. An expression for the discontinuity in the nucleon binding energy in the vicinity of a magic nucleus is obtained. The role of the residual interaction is analyzed. It is shown that the width of the Fermi-surface diffuseness due to the residual interaction is proportional to the squared vector of the quasi-particle orbital angular momentum. The values of the corresponding proportionality factors (the coupling constant for quasi particles) are determined from the experimental data for 52 magic nuclei. The rapid drop of the residual interaction with increasing nuclear size is demonstrated. (7 figures, 3 tables) (U.S.)
Precise measurements of neutron capture cross sections for FP
International Nuclear Information System (INIS)
Nakamura, Shoji; Harada, Hideo; Katoh, Toshio
2000-01-01
The thermal neutron capture cross sections (σ 0 ) and the resonance integrals (I 0 ) of some fission products (FP), such as 137 Cs, 90 Sr, 99 Tc, 129 I and 135 Cs, were measured by the activation and γ-ray spectroscopic methods. Moreover, the cross section measurements were done for other FP elements, such as 127 I, 133 Cs and 134 Cs. This paper provides the summary of the FP cross section measurements, which have been performed by authors. (author)
Shell effects in the nuclear deformation energy
International Nuclear Information System (INIS)
Ross, C.K.
1973-01-01
A new approach to shell effects in the Strutinsky method for calculating nuclear deformation energy is evaluated and the suggestion of non-conservation of angular momentum in the same method is resolved. Shell effects on the deformation energy in rotational bands of deformed nuclei are discussed. (B.F.G.)
Phebus FP. An international severe accident research programme
International Nuclear Information System (INIS)
Hardt, P.; Tattegrain, A.
1995-01-01
The main hazard during a hypothetical severe nuclear reactor accident resides in its fission product (FP) inventory. For this reason, the behaviour of FPs has been extensively studied, with the aim of determining the potential source to the environment. The Phebus FP programme proposes a novel, integral approach to this research. After 5 years of construction and of analytical preparation the Phebus FP programme has been supplying a large volume of new experimental data. Their processing by code calculations is presently a major challenge to all partners. The intense collaboration of 25 organizations from 15 countries has proven to be a major asset of Phebus FP. (author). 6 refs., 2 figs
FP-4 and FP-5 Euratom research activities in the field of plant life management
International Nuclear Information System (INIS)
Lemaitre, P.; Goethem, G. van
2001-01-01
In this paper an overview is given of the European Union (EU) Euratom research conducted through shared cost and concerted actions in the field of plant life management. After a general introduction on the organisation of the research framework programmes the achievements of the 4th framework programme (FP-4/1994-1998) and the activities under the 5th framework programme (FP-5/1999-2002) in the field of plant life management are presented and discussed in detail. Besides technological safety requirements, socio-economic aspects are becoming increasingly important due to the level of public and political acceptance and to the economic pressure of deregulated electricity markets. It is shown that research conducted in the Euratom framework may contribute to meet these requirements, thereby maintaining nuclear power as a competitive and sustainable option for the energy policy of the European Union. (author)
International Nuclear Information System (INIS)
Anon.
1995-01-01
The recent detection of intergalactic helium by NASA's Astro-2 mission backs up two earlier measurements by ESA and the University of California, San Diego, using instruments aboard the Hubble Space Telescope. Taken together, these results give strong evidence that this helium is primordial, confirming a key prediction of the Big Bang theory. The amount of helium the results imply could also account for some of the Universe's invisible dark matter - material which affects galactic motion but is otherwise undetectable. According to theory, helium nuclei formed at around 100 seconds after the Big Bang, but the amount of helium depended on even earlier events. Initially, protons turned into neutrons with the same probability that neutrons turned into protons. But after about one second, the Universe had cooled down enough for the weak interaction to freeze out. Neutrons continued to decay into the slightly lighter protons, whilst the opposite reaction became much more scarce. At around 100 seconds, thermonuclear fusion reactions could begin, and all the neutrons that were left became absorbed into helium nuclei, leaving the remaining protons locked up in hydrogen. The ratio of helium to hydrogen was therefore determined by events occurring when the Universe was just one second old. Standard models of primordial nucleosynthesis fix this ratio at slightly less than 2 5% by mass. All heavier elements were cooked up much later in the stars, and amount to less than 1 % of the Universe's mass. These predictions have been borne out remarkably well by observation, although proof of the primordial origins of hydrogen and helium has remained elusive until now. Big Bang nucleosynthesis goes on to estimate that primordial baryonic matter in the form of light nuclei could account for around 10% of the Universe's dark matter. All three recent measurements used the same technique of looking at distant quasars, some of the most luminous objects in the Universe, to
Systematics of light nuclei in a relativistic model
International Nuclear Information System (INIS)
Price, C.E.
1988-01-01
The results of relativistic mean field calculations for non-spherical nuclei are presented and discussed. The need for non-linear scalar meson self-couplings in order to describe the properties of s-d shell nuclei is emphasized along with the importance of self-consistency in calculations of magnetic moments of odd-mass nuclei. 16 refs., 3 figs., 2 tabs
Energy Technology Data Exchange (ETDEWEB)
Khouaja, A
2003-12-01
Using the direct method, the mean energy integrated reaction cross section was investigated for a wide range of neutron-rich nuclei (N {yields} Ar) at GANIL. Using the parametrisation of S. Kox, 19 new radii measurements (reaction cross sections) were obtained. By the isotopic, isotonic and isospin dependence, the evolution of the strong reduced radius was studied according to the excess of neutrons. New halo effect is proposed to the nuclei of Mg{sup 35} and S{sup 44}. A quadratic parametrization is also proposed for the nuclear radius as a function of the isospin in the region of closed shells N=8 and N=28. In addition, we used a modified version of the Glauber model for studying the tail and matter distribution of nuclei. Indeed, using our new data the effects of the nuclear size (root mean square radii) and the matter distribution (diffusivity) were de-convoluted for each isotope. The root mean square radii of Na and Mg isotopes obtained so far were consistent with the ones from literature. (author)
Shell model Monte Carlo methods
International Nuclear Information System (INIS)
Koonin, S.E.; Dean, D.J.; Langanke, K.
1997-01-01
We review quantum Monte Carlo methods for dealing with large shell model problems. These methods reduce the imaginary-time many-body evolution operator to a coherent superposition of one-body evolutions in fluctuating one-body fields; the resultant path integral is evaluated stochastically. We first discuss the motivation, formalism, and implementation of such Shell Model Monte Carlo (SMMC) methods. There then follows a sampler of results and insights obtained from a number of applications. These include the ground state and thermal properties of pf-shell nuclei, the thermal and rotational behavior of rare-earth and γ-soft nuclei, and the calculation of double beta-decay matrix elements. Finally, prospects for further progress in such calculations are discussed. (orig.)
Shell model Monte Carlo methods
International Nuclear Information System (INIS)
Koonin, S.E.
1996-01-01
We review quantum Monte Carlo methods for dealing with large shell model problems. These methods reduce the imaginary-time many-body evolution operator to a coherent superposition of one-body evolutions in fluctuating one-body fields; resultant path integral is evaluated stochastically. We first discuss the motivation, formalism, and implementation of such Shell Model Monte Carlo methods. There then follows a sampler of results and insights obtained from a number of applications. These include the ground state and thermal properties of pf-shell nuclei, thermal behavior of γ-soft nuclei, and calculation of double beta-decay matrix elements. Finally, prospects for further progress in such calculations are discussed. 87 refs
High-spin excitations of atomic nuclei
International Nuclear Information System (INIS)
Xu Furong; National Laboratory of Heavy Ion Physics, Lanzhou; Chinese Academy of Sciences, Beijing
2004-01-01
The authors used the cranking shell model to investigate the high-spin motions and structures of atomic nuclei. The authors focus the collective rotations of the A∼50, 80 and 110 nuclei. The A∼50 calculations show complicated g spectroscopy, which can have significant vibration effects. The A≅80 N≅Z nuclei show rich shape coexistence with prolate and oblate rotational bands. The A≅110 nuclei near the r-process path can have well-deformed oblate shapes that become yrast and more stable with increasing rotational frequency. As another important investigation, the authors used the configuration-constrained adiabatic method to calculate the multi-quasiparticle high-K states in the A∼130, 180 and superheavy regions. The calculations show significant shape polarizations due to quasi-particle excitations for soft nuclei, which should be considered in the investigations of high-K states. The authors predicted some important high-K isomers, e.g., the 8 - isomers in the unstable nuclei of 140 Dy and 188 Pb, which have been confirmed in experiments. In superheavy nuclei, our calculations show systematic existence of high-K states. The high-K excitations can increase the productions of synthesis and the survival probabilities of superheavy nuclei. (authors)
Study of single-nucleon spectroscopic characteristics in light nuclei
International Nuclear Information System (INIS)
Zhusupova, K.A.
1998-01-01
Single-nucleon characteristics of 1 p-shell nuclei are investigated in the thesis. These characteristics are necessary for describing nuclear processes leaded to separation of target nuclei or to addition of one nucleon to it. Multi-particle shell model and three-body cluster model (for 6 L i and 9 Be) are used. It is shown that shell model explains well spectroscopic S-factors for stripping and pick-up reactions of nucleon. Three body α2 N-model reproduces well S-factors and momentum distribution extracted from (e, e p) reactions for separation of proton from ground state of 6 L i nucleus accompanied by appearance of ground and high exited states of 5 He nucleolus. The classification and explanation for small value nucleon partial widths for high lying states for odd nuclei 1 p-shell with isospin T=3/2 are given. (author)
Kruecken, R; Voulot, D
2007-01-01
We are aiming at the investigation of single particle properties of neutron-rich nuclei in the region of the "island of inversion" where intruder states from the $\\{fp}$-shell favour deformed ground states instead of the normal spherical $\\textit{sd}$-shell states. As first experiment, we propose to study single particle states in the neutron-rich isotope $^{31}$Mg. The nucleus will be populated by a one-neutron transfer reaction with a $^{30}$Mg beam at 3 MeV/u obtained from REX-ISOLDE impinging on a CD$_{2}$ target. The $\\gamma$-rays will be detected by the MINIBALL array and the particles by a newly built set-up of segmented Si detectors with a angular coverage of nearly 4$\\pi$. Relative spectroscopic factors extracted from the cross sections will enable us to pin down the configurations of the populated states. These will be compared to recent shell model calculations involving new residual interactions. This will shed new light on the evolution of single particle structure leading to the breaking of the ...
Theoretical description and predictions of the properties of superheavy nuclei
Energy Technology Data Exchange (ETDEWEB)
Sobiczewski, A [Department of Theoretical Physics, Andrzej Soltan Institute for Nuclear Studies (Poland)
2009-12-31
Theoretical descriptions of superheavy atomic nuclei are shortly reviewed and illustrated by their results. Such properties of these nuclei as their shapes, masses, fission barriers, decay modes, decay energies, half-lives, are discussed. Special attention is given to the shell structure of the nuclei, due to which they exist. The role of the physical studies of the superheavy nuclei for the chemical research on the superheavy elements and, more generally, the relationship between these two kinds of investigation is underlined. This stresses the importance of close cooperation between physicists and chemists, experimentalists and theoreticians, in these studies.
Strength of Coriolis Coupling in actinide nuclei
International Nuclear Information System (INIS)
Peker, L.K.; Rasmussen, J.O.; Hamilton, J.H.
1982-01-01
Coriolis Coupling V/sub cor/ plays an important role in deformed nuclei. V/sub cor/ is proportional to h 2 /J[j (j + 1) -Ω (Ω + 1)]/sup 1/2/ and therefore is particularly significant in the nuclei with large j and low Ω Nilsson levels close to Fermi surface: n(i/sub 13/2/) in A = 150 to 170 rare-earth nuclei and p(i/sub 13/2/) and n(j/sub 15/2/) in A greater than or equal to 224 actinide nuclei. Because of larger j (n(j/sub 15/2/) versus n(i/sub 13/2/)) and smaller deformations (β approx. = 0.22 versus β 0.28) it was reasonable to expect that in actinide nuclei Coriolis effects are stronger than in the rare earth nuclei. Recently it was realized that the strength of observed Coriolis effects depends not only on the genuine Coriolis Coupling but also on the interplay between Coriolis ad pairing forces which leads to an interference between the wave functions of two mixing rotational bands. As a consequence the effective interaction V/sub eff/ of both bands is an oscillating function of the degree of shell filling (or chemical potential lambda F). It was shown that in the rare earth nuclei this interference strongly influenced conclusions about the trends in the Coriolis coupling strength and explained many of the observed band-mixing features (the sharpness of back banding curves, details of the blocking effect etc.). From theoretical analysis it was concluded that in the majority of actinide nuclei the effective interaction V/sub eff/ is strong, and therefore the Coriolis band-mixing have to be very strong. In this paper we would like to demonstrate that contrary to these predictions experimental data suggest that Coriolis band mixing in studied actinide nuclei is relatively weak and possibly significantly weaker than in rare earth nuclei
DASH-FP, Multicomponent Time-Dependent Concentration Diffusion
International Nuclear Information System (INIS)
Apperson, C.E. Jr.; Carruthers, L.M.; Shinn, J.F.; Lee, C.E.
1995-01-01
1 - Description of program or function: The program DASH-FP calculates the transient concentration of multiple diffusing species with radioactive decay. 2 - Method of solution: Uses finite difference and exponential operator techniques
Stability and production of superheavy nuclei
International Nuclear Information System (INIS)
Moeller, P.; Los Alamos National Lab., NM; Nix, J.R.
1997-01-01
Beyond uranium heavy elements rapidly become increasingly unstable with respect to spontaneous fission as the proton number Z increases, because of the disruptive effect of the long-range Coulomb force. However, in the region just beyond Z = 100 magic proton and neutron numbers and the associated shell structure enhances nuclear stability sufficient to allow observation of additional nuclei. Some thirty years ago it was speculated that an island of spherical, relatively stable superheavy nuclei would exist near the next doubly magic proton-neutron combination beyond 208 Pb, that is, at proton number Z 114 and neutron number N = 184. Theory and experiment now show that there also exists a rock of stability in the vicinity of Z = 110 and N = 162 between the actinide region, which previously was the end of the peninsula of known elements, and the predicted island of spherical superheavy nuclei slightly southwest of the magic numbers Z = 114 and N = 184. The authors review here the stability properties of the heavy region of nuclei. Just as the decay properties of nuclei in the heavy region depend strongly on shell structure, this structure also dramatically affects the fusion entrance channel. The six most recently discovered new elements were all formed in cold-fusion reactions. They discuss here the effect of the doubly magic structure of the target in cold-fusion reactions on the fusion barrier and on dissipation
Fragmentation of relativistic nuclei
International Nuclear Information System (INIS)
Cork, B.
1975-06-01
Nuclei with energies of several GeV/n interact with hadrons and produce fragments that encompass the fields of nuclear physics, meson physics, and particle physics. Experimental results are now available to explore problems in nuclear physics such as the validity of the shell model to explain the momentum distribution of fragments, the contribution of giant dipole resonances to fragment production cross sections, the effective Coulomb barrier, and nuclear temperatures. A new approach to meson physics is possible by exploring the nucleon charge-exchange process. Particle physics problems are explored by measuring the energy and target dependence of isotope production cross sections, thus determining if limiting fragmentation and target factorization are valid, and measuring total cross sections to determine if the factorization relation, sigma/sub AB/ 2 = sigma/sub AA/ . sigma/sub BB/, is violated. Also, new experiments have been done to measure the angular distribution of fragments that could be explained as nuclear shock waves, and to explore for ultradense matter produced by very heavy ions incident on heavy atoms. (12 figures, 2 tables)
Studies of yrast and continuum states in A = 140 to 160 nuclei. Progress report for 1983
International Nuclear Information System (INIS)
Daly, P.J.
1983-12-01
The structure of nuclei, principally in the A-150 region, has been studied by in-beam γ-ray spectroscopy using heavy ion beams from the Argonne Tandem/Linac. New structural information was obtained for many shell model nuclei around 146 Gd, for the shape transitional nuclei 153 Dy and 154 Dy, and for the nuclei 147 Gd, 186 Hg, and 187 Hg at high-spin
Energy Technology Data Exchange (ETDEWEB)
Gaudefroy, L
2005-09-15
The study of the N=28 shell closure has been presented as well as its astrophysical implications. Moreover the structure of neutron rich nuclei around N=32/34 and 40 was studied. The N=28 shell closure has been studied trough the one neutron transfer reaction on {sup 44,46}Ar nuclei. Excitation energies of states in {sup 45,47}Ar nuclei have been obtained, as well as their angular momenta and spectroscopic factors. These results were used to show that N=28 is still a good magic number in the argon isotopic chain. We interpreted the evolution of the spin-orbit partner gaps in terms of the tensor monopolar proton-neutron interaction. Thanks to this latter, we showed it is not necessary to summon up a reduction of the intensity of the spin-orbit force in order to explain this evolution in N=29 isotopes from calcium to argon chains. The neutron capture rates on {sup 44,46}Ar have been determined thanks to the results of the transfer reaction. Their influence on the nucleosynthesis of {sup 46,48}Ca was studied. We proposed stellar conditions to account for the abnormal isotopic ratio observed in the Allende meteorite concerning {sup 46,48}Ca isotopes. The beta decay and gamma spectroscopy of neutron rich nuclei in the scandium to cobalt region has been studied. We showed that beta decay process is dominated by the {nu}f{sub 5/2} {yields} {pi}f{sub 7/2} Gamow-Teller transition. Moreover, we demonstrated that the {nu}g{sub 9/2} hinders this process in the studied nuclei, and influences their structure, by implying the existence of isomers. Our results show that N=34 is not a magic number in the titanium chain and the superior ones. (author)
^2H(^18F,p)^19F Study at 6 MeV/u
Kozub, R. L.; Nesaraja, C. D.; Moazen, B. H.; Scott, J. P.; Bardayan, D. W.; Blackmon, J. C.; Gross, C. J.; Shapira, D.; Smith, M. S.; Batchelder, J. C.; Brune, C. R.; Champagne, A. E.; Sahin, L.; Cizewski, J. A.; Thomas, J. S.; Davinson, T.; Woods, P. J.; Greife, U.; Jewett, C.; Livesay, R. J.; Ma, Z.; Parker, P. D.
2003-04-01
The degree to which the (p,α) and (p,γ) reactions destroy ^18F at temperatures ˜1-4 x 10^8 K is important for understanding the synthesis of nuclei in nova explosions and for using ^18F as a monitor of nova mechanisms in gamma ray astronomy. The reactions are dominated by low-lying proton resonances near the ^18F+p threshold (E_x=6.411 MeV excitation energy in ^19Ne). To gain further information about these resonances, we have used the inverse ^18F(d,p)^19F neutron transfer reaction at the Holifield Radioactive Ion Beam Facility to selectively populate corresponding mirror states in ^19F. Proton angular distributions were measured for states in ^19F in the excitation energy range 0-9 MeV. Results and implications for the ^18F+p reactions and nuclear structure will be presented. ^1Supported by DOE. ^2ORNL is managed by UT-Battelle, LLC, for the USDOE.
International Nuclear Information System (INIS)
Fossez, Kevin
2014-01-01
Small open quantum systems, whose properties are profoundly affected by the environment of continuum states, are intensely studied in various fields of Physics: nuclear physics, atomic and molecular physics, quantum optics, etc. These different many-body systems, in spite of their specific features, have generic properties which are common to all weakly bound or unbound systems close to the threshold. Coupling to the continuum is essential to describe the low-energy nuclear reactions of astrophysical interest, the formation of halo states in nuclei, atomic clusters and dipolar anions, or the near-threshold two neutron and alpha particle correlations (clustering). Recently, the open quantum system extension of the nuclear shell model, the Gamow shell model (GSM), based on the Berggren ensemble, has been applied successfully for the description of resonant states spectra in atomic nuclei. The coupled-channel formulation of the GSM (GSM-CC) allows to describe various low-energy nuclear reactions. In this work, the GSM-CC is formulated and applied for the description of proton/neutron radiative capture reactions of astrophysical interest, such as: 17 F(p, γ) 18 Ne, 7 Be(p, γ) 8 B and 7 Li(n, γ) 8 Li. Moreover, for the first time, the GSM has been applied in atomic physics for the description of spectra of dipolar anions. Systematic investigation of the hydrogen cyanide dipolar anion (HCN - ) allowed to identify the collective bands of states both in the strong coupling regime, for weakly bound halo states, and in the weak coupling regime above the dissociation threshold. In the strong coupling regime, K J = 0 anion a rotational band has been found. Above the threshold, K J quantum number is not conserved. Resonances in this regime form rotational bands according to the angular momentum of the rotating molecule, whereas the band head energies and the lifetimes depend predominantly on the external electron wave function. (author) [fr
Metabolism of 123I-FP-CIT in humans
International Nuclear Information System (INIS)
Tanaka, Akihiro; Okano, Kyoko; Tamagami, Hiroshi
1999-01-01
The metabolism of N-(3-fluoropropyl)-2β-carbomethoxy-3β-(4-iodophenyl)nortropane ( 123 I) ( 123 I-FP-CIT) in healthy humans was studied. Plasma and urine samples, obtained after i.v. administration of 123 I-FP-CIT, were analyzed using the two-dimensional thin-layer chromatography technique. Eleven radiochemical components were detected in both plasma and urine, and four of them were the parent 123 I-FP-CIT and its metabolites, N-(3-fluoropropyl)-2β-carboxy-3β-(4-iodophenyl)nortropane ( 123 I) ( 123 I-acid), 2β-carboxy-3β-(4-iodophenyl)nortropane ( 123 I) ( 123 I-nor-acid) and 2β-carbomethoxy-3β-(4-iodophenyl)nortropane ( 123 I) ( 123 I-nor-CIT). These four identified radiochemical components occupied about 80% or more in ratio of the radiochemical components in the plasma and urine. In the metabolites of 123 I-FP-CIT, the high polar metabolites- 123 I-acid and 123 I-nor-acid-were found to be the major components, while lipophilic 123 I-nor-CIT was a minor component. Free iodide ( 123 I - ) was not found in the plasma or urine. Thus, the main metabolic reactions which 123 I-FP-CIT undergoes in humans seem to be hydrolysis of the ester bond and N-dealkylation. In vivo deiodination of 123 I-FP-CIT was found to be minimum. Current results suggest that the metabolites of 123 I-FP-CIT hardly influence evaluation of the dopamine transporter in the human brain. (author)
The short range effective interaction and the spectra of calcium isotopes in (f-p) space
International Nuclear Information System (INIS)
Qing-ying, Z.; Shen-wu, L.; Jian-xin, W.
1986-01-01
In this work, the authors use a new type of extremely short range interaction, the double delta interaction (DDI) to calculate the low-lying spectra of calcium isotopes /sup 41/Ca through /sup 48/Ca. The configuration space (f-p) includes configurations ( f/sub 7/2//sup n/ ) and ( f/sub 7/2//sup n-1/2p/sub 3/2/). The calculated energies are compared with experimental data for 75 levels. For comparison, they also use usual modified surface delta interaction (MSDI) to calculate the same spectra aforementioned. It is clear that the results calculated with DDI are better than with MSDI. Therefore, in the short-range effective interaction the addition of body delta force to the modified surface delta force may improve the agreement with experiment. The authors believe that the conclusion will not be changed if one enlarges the shell model space
Fission of nuclei far from stability
International Nuclear Information System (INIS)
Schmidt, K.H.; Benlliure, J.; Junghans, A.R.
2000-11-01
The secondary-beam facility of GSI provided the technical equipment for a new kind of fission experiment. Fission properties of short-lived neutron-deficient nuclei have been investigated in inverse kinematics. The measured element distributions reveal new kinds of systematics on shell structure and even-odd effects and lead to an improved understanding of structure effects in nuclear fission. Prospects for further experimental studies are discussed. (orig.)
P-shell hyperon binding energies
International Nuclear Information System (INIS)
Koetsier, D.; Amos, K.
1991-01-01
A shell model for lambda hypernuclei has been used to determine the binding energy of the hyperon in nuclei throughout the p shell. Conventional (Cohen and Kurath) potential energies for nucleon-nucleon interactions were used with hyperon-nucleon interactions taken from Nijmegen one boson exchange potentials. The hyperon binding energies calculated from these potentials compare well with measured values. 7 refs., 2 figs
Shell effects in the superasymmetric fission
Mirea, M
2002-01-01
A new formalism based on the Landau-Zener promotion mechanism intends to explain the fine structure of alpha and cluster decay. The analysis of this phenomenon is accomplished by following the modality in which the shells are reorganized during the decay process beginning with the initial ground state of the parent towards the final configuration of two separated nuclei. A realistic level scheme is obtained in the framework of the superasymmetric two-center shell model. (author)
CERN in FP7: very successful participation so far
2009-01-01
The first two years of the seventh Framework Programme were very successful for CERN – 27 EU projects were selected for funding in 2007 and 2008, with the total EC contribution exceeding 33 million euros.The seventh European Union Framework Programme for research, technological development and demonstration activities (FP7) started on 1 January 2007 and will cover the period from 2007 to 2013. With a total budget of 50.5 billion euros, FP7 is the largest Framework Programme in the history of the EU. FP7 consists of four major sub-programmes, referred to as "Specific Programmes": "Cooperation" is focused on collaborative research projects and is divided into 10 thematic areas. "Ideas" is a new EU programme for funding frontier research in all fields of science. "Capacities" aims at strengthening the research capacities in Europe, including research infrastructures and e-infrastructures. Finally, "People" succeeds the p...
The PHEBUS FP project. Status report 1989-1990
International Nuclear Information System (INIS)
Scott de Martinville, E.F.; Delchambre, P.; Von der Hardt, P.
1992-01-01
Major achievements of PHEBUS Fission Product (FP) Programme during the year 1989 have been - seismic safety studies and civil engineering design of buildings and major components - transition into the detail design phase of experimental equipment and instrumentation - first orders for large components and other long delivery items - detailed definition of the test matrix - adaptation of existing, and generation of specific computation tools - dimensioning verification of the overall design proposal and of the first irradiation test - specific supporting studies, like analytical aerosol experiments, FP chemistry research, gamma spectrometry system layout, neutronic calculations. This report describes the experimental equipment, as defined in spring of 1990, and the underlying analytical studies. It updates earlier publications but can be read as a stand-alone description of PHEBUS FP. The present schedule forecasts the first in-pile test, with fresh fuel, by the middle of 1992
Super-hypernuclei in the quark-shell model, 2
International Nuclear Information System (INIS)
Terazawa, Hidezumi.
1989-07-01
By following the previous paper, where the quark-shell model of nuclei in quantum chromodynamics is briefly reviewed, a short review of the MIT bag model of nuclei is presented for comparison and a simple estimate of the Hλ ('hexalambda') mass is also made for illustration. Furthermore, an even shorter review of the 'nucleon cluster model' of nuclei is presented for further comparison. (J.P.N.)
Study of 19F and 19Ne mirror nuclei
International Nuclear Information System (INIS)
Lebrun, Claude.
1976-01-01
The electromagnetic properties of the mirror nuclei 19 F and 19 Ne were studied using the 18 O(d,nγ) 19 F, 17 O( 3 He,nγ) 19 Ne and 19 F(p,nγ) 19 Ne reactions. Lifetimes of 8 levels in 19 F and 11 levels in 19 Ne have been measured using the Doppler shift attenuation method. Weak and strong components of M 1 , E 1 and E 2 transition strengths are compared with shell model predictions. M 1 and E 2 transition strengths of conjugated nuclei (A=18 to A=34) are compiled and compared with wide configuration space shell models [fr
Role of antisymmetric spin-orbit component in effective interactions in the sd-shell
International Nuclear Information System (INIS)
Yoshinada, K.
1981-10-01
The antisymmetric spin-orbit interaction (ALS) proposed for sd-shell nuclei is investigated. It is shown that the centroid energy of the d sub(5/2) - d sub(3/2) interactions plays a crucial role in reproducing the excited band spectra of A = 18 - 24 nuclei. An empirical effective interaction without ALS component is proposed to reproduce the observed spectra of light sd-shell nuclei. (author)
Statistical properties of the nuclear shell-model Hamiltonian
International Nuclear Information System (INIS)
Dias, H.; Hussein, M.S.; Oliveira, N.A. de
1986-01-01
The statistical properties of realistic nuclear shell-model Hamiltonian are investigated in sd-shell nuclei. The probability distribution of the basic-vector amplitude is calculated and compared with the Porter-Thomas distribution. Relevance of the results to the calculation of the giant resonance mixing parameter is pointed out. (Author) [pt
DEFF Research Database (Denmark)
Almegaard, Henrik
2004-01-01
A new statical and conceptual model for membrane shell structures - the stringer system - has been found. The principle was first published at the IASS conference in Copenhagen (OHL91), and later the theory has been further developed (ALMO3)(ALMO4). From the analysis of the stringer model it can...... be concluded that all membrane shells can be described by a limited number of basic configurations of which quite a few have free edges....
International Nuclear Information System (INIS)
Angelique, J.C.; Orr, N.A.
1997-01-01
The study of the nuclei far off stability valley is of much interest for testing the nuclear models established for the stable nuclei but also for astrophysics to understand the nucleosynthesis. Experiments aim to measure the mass and lifetime, to build the decay schemes and also to study the structure and the properties of these nuclei. The radioactive beam group focused its research on light neutron-rich nuclei having a halo neutron structure. Mass measurements in N ∼ Z nuclei namely in A ∼ 60-80 proton-rich nuclei, important for understanding the rp process, are mentioned, as well as in nuclei in the 100 Sn region. In the newly obtained 26 O and 28 O nuclei the lifetimes, the probabilities of emission of one for more neutrons were determined. The data analysis has permitted to determine also for the first time the lifetimes of 27,29 F and 30 Ne. Studies of nuclei in the 100 Sn region, near the proton drip line in the ground and isomeric states are now under way. The spectroscopy (energy levels, gamma emissions, etc.) of the neutron-rich nuclei produced by the 36 S fragmentation has been carried out in 31 Ne, 17 B and 29 F. Studies by Coulomb excitation of the 2 + excited states and associated probability B (E2) in O, Ne, Ni and Zn are now analysed
Exotic light nuclei and nuclei in the lead region
International Nuclear Information System (INIS)
Poppelier, N.A.F.M.
1989-01-01
Three methods are discussed for modifying, or renormalizing, a truncated nuclear hamiltonian such that the wave functions obtained by diagonalizing this modified or effective hamiltoniandescribe the nucleus as well as possible: deriving the hamiltonian directly from a realistic nucleon-nucleon interaction between free nucleons; parametrizing the hamiltonian in terms of a number of parameters and determining these parameters from a least-squares fit of calculated properties to experimental data; approximating the nucleon-nucleon (NN) interaction between two nucleons in a nucleus by a simple analytic expression. An effective hamiltonian derived following the second method is applied in a theoretical study of exotic nuclei in the region of Z=2-9 and A=4-30 and the problem of the neutron halo in 11 Li is discussed. Results of shell-model calculations of 20i Pb and nuclei in its neighbourhood are presented in which an effective hamiltonian was employed derived with the last method. The quenching of M1 strength in 208 Pb, and the spectroscopic factors measured in proton knock-out reactions could be described quite satisfactory. Finally, a method is presented for deriving the effective hamiltonian directly from the realistic NN interaction with algebraic techniques. (H.W.). 114 refs.; 34 figs.; 12 tabs.; schemes
Mirror energy difference and the structure of loosely bound proton-rich nuclei around A =20
Yuan, Cenxi; Qi, Chong; Xu, Furong; Suzuki, Toshio; Otsuka, Takaharu
2014-04-01
The properties of loosely bound proton-rich nuclei around A =20 are investigated within the framework of the nuclear shell model. In these nuclei, the strength of the effective interactions involving the loosely bound proton s1/2 orbit is significantly reduced in comparison with that of those in their mirror nuclei. We evaluate the reduction of the effective interaction by calculating the monopole-based-universal interaction (VMU) in the Woods-Saxon basis. The shell-model Hamiltonian in the sd shell, such as USD, can thus be modified to reproduce the binding energies and energy levels of the weakly bound proton-rich nuclei around A =20. The effect of the reduction of the effective interaction on the structure and decay properties of these nuclei is also discussed.
PHEBUS FP release analysis using a microstructure-based code
International Nuclear Information System (INIS)
Carlucci, L.N.
1992-03-01
The results of pre-test fission-product (FP) release analyses of the first two PHEBUS FP experiments, FPT0 and FPT1, indicate that the FREEDOM microstructure-based code predicts significant differences in both the timing and percent of gaseous FP releases for the two tests. To provide an indication of its predictive capability, FREEDOM was also used to model the high-burnup fuel tested in the Oak Ridge National Laboratory experiments VI-2 and VI-3. For these, the code was found to overpredict releases during the early stages of the tests and to underpredict releases during the later stages. The release kinetics in both tests were reasonably predicted, however. In view of the above, it is likely that the FREEDOM predictions of the final cumulative releases for the first two PHEBUS FP tests are lower-bound estimates. However, the significant difference in the predicted timing of initial releases for the two tests is felt to be indicative of what will occur. Therefore, this difference should be considered in the planning and conduct of the two tests, particularly aspects related to on-line measurements
Utilisation des modules ATM pour le projet FP420
Renaglia, T
2006-01-01
Le but de cette note est de résumer les premières caractéristiques de l'intégration de 2 modules ATM pour le projet FP420 (voir note technique EDMS n° 743628) ainsi que la liste des problèmes découverts à ce jour sur l
Modeling photoabsorption of the asFP595 chromophore.
Bravaya, Ksenia B; Bochenkova, Anastasia V; Granovsky, Alexander A; Savitsky, Alexander P; Nemukhin, Alexander V
2008-09-18
The fluorescent protein asFP595 is a promising photoswitchable biomarker for studying processes in living cells. We present the results of a high level theoretical study of photoabsorption properties of the model asFP595 chromophore molecule in biologically relevant protonation states: anionic, zwitterionic, and neutral. Ground state equilibrium geometry parameters are optimized in the PBE0/(aug)-cc-pVDZ density functional theory approximation. An augmented version of multiconfigurational quasidegenerate perturbation theory (aug-MCQDPT2) following the state-averaged CASSCF/(aug)-cc-pVDZ calculations is used to estimate the vertical S0-S1 excitation energies for all chromophore species. An accuracy of this approach is validated by comparing the computed estimates of the S0-S1 absorption maximum of the closely related chromophore from the DsRed protein to the known experimental value in the gas phase. An influence of the CASSCF active space on the aug-MCQDPT2 excitation energies is analyzed. The zwitterionic form of the asFP595 chromophore is found to be the most sensitive to a particular choice and amount of active orbitals. This observation is explained by the charge-transfer type of the S0-S1 transition involving the entire conjugated pi-electron system for the zwitterionic protonation state. According to the calculation results, the anionic form in the trans conformation is found to possess the most red-shifted absorption band with the maximum located at 543 nm. The bands of the zwitterionic and neutral forms are considerably blue-shifted compared to those of the anionic form. These conclusions are at variance with the results obtained in the TDDFT approximation for the asFP595 chromophore. The absorption wavelengths computed in the aug-MCQDPT2/CASSCF theory are as follows: 543 (535), 470 (476), and 415 (417) nm for the anionic, zwitterionic, and neutral forms of the trans and cis (in parentheses) isomers of the asFP595 chromophore. These data can be used as a
Relativistic mean field theory for unstable nuclei
International Nuclear Information System (INIS)
Toki, Hiroshi
2000-01-01
We discuss the properties of unstable nuclei in the framework of the relativistic mean field (RMF) theory. We take the RMF theory as a phenomenological theory with several parameters, whose form is constrained by the successful microscopic theory (RBHF), and whose values are extracted from the experimental values of unstable nuclei. We find the outcome with the newly obtained parameter sets (TM1 and TMA) is promising in comparison with various experimental data. We calculate systematically the ground state properties of even-even nuclei up to the drip lines; about 2000 nuclei. We find that the neutron magic shells (N=82, 128) at the standard magic numbers stay at the same numbers even far from the stability line and hence provide the feature of the r-process nuclei. However, many proton magic numbers disappear at the neutron numbers far away from the magic numbers due to the deformations. We discuss how to describe giant resonances for the case of the non-linear coupling terms for the sigma and omega mesons in the relativistic RPA. We mention also the importance of the relativistic effect on the spin observables as the Gamow-Teller strength and the longitudinal and transverse spin responses. (author)
Chaos in nuclei: Theory and experiment
Muñoz, L.; Molina, R. A.; Gómez, J. M. G.
2018-05-01
During the last three decades the quest for chaos in nuclei has been quite intensive, both with theoretical calculations using nuclear models and with detailed analyses of experimental data. In this paper we outline the concept and characteristics of quantum chaos in two different approaches, the random matrix theory fluctuations and the time series fluctuations. Then we discuss the theoretical and experimental evidence of chaos in nuclei. Theoretical calculations, especially shell-model calculations, have shown a strongly chaotic behavior of bound states in regions of high level density. The analysis of experimental data has shown a strongly chaotic behavior of nuclear resonances just above the one-nucleon emission threshold. For bound states, combining experimental data of a large number of nuclei, a tendency towards chaotic motion is observed in spherical nuclei, while deformed nuclei exhibit a more regular behavior associated to the collective motion. On the other hand, it had never been possible to observe chaos in the experimental bound energy levels of any single nucleus. However, the complete experimental spectrum of the first 151 states up to excitation energies of 6.20 MeV in the 208Pb nucleus have been recently identified and the analysis of its spectral fluctuations clearly shows the existence of chaotic motion.
Perturbation theory instead of large scale shell model calculations
International Nuclear Information System (INIS)
Feldmeier, H.; Mankos, P.
1977-01-01
Results of large scale shell model calculations for (sd)-shell nuclei are compared with a perturbation theory provides an excellent approximation when the SU(3)-basis is used as a starting point. The results indicate that perturbation theory treatment in an SU(3)-basis including 2hω excitations should be preferable to a full diagonalization within the (sd)-shell. (orig.) [de
Effective interactions and coupling schemes in nuclei
International Nuclear Information System (INIS)
Talmi, I.
1994-01-01
Eigenstates of the shell model are obtained by diagonalization of the Hamiltonian submatrix defined by a given shell model subspace. Matrix elements of the effective nuclear interaction can be determined from experiment in a consistent way. This approach was introduced in 1956 with the 38 Cl- 40 K spectra, has been applied in many cases and its latest success is in the s, d shell. This way, general features of the effective interaction have been determined. The T=1 interaction is diagonal in the seniority scheme as clearly demonstrated in proton 1g 9/2 n and 1h 11/2 n configurations and in the description of semimagic nuclei by generalized seniority. Apart from a strong and attractive pairing term, T=1 interactions are repulsive on the average. The T=0 interaction is attractive and is the origin of the central potential well in which nucleons are bound. It breaks seniority in a major way leading to deformed nuclei and rotational spectra. Such an interaction may be approximated by a quadrupole-quadrupole interaction which is the basis of the interacting boson model. Identical nucleons with pairing and quadrupole interactions cannot be models of actual nuclei. Symmetry properties of states with maximum T are very different from those of ground states of actual nuclei. The T=1 interaction between identical nucleons cannot be approximated by pairing and quadrupole interactions. The rich variety of nuclear spectra is due to the competition between seniority conserving T=1 interactions and the T=0 quadrupole interaction between protons and neutrons. (orig.)
Selfconsistent calculations for hyperdeformed nuclei
Energy Technology Data Exchange (ETDEWEB)
Molique, H.; Dobaczewski, J.; Dudek, J.; Luo, W.D. [Universite Louis Pasteur, Strasbourg (France)
1996-12-31
Properties of the hyperdeformed nuclei in the A {approximately} 170 mass range are re-examined using the self-consistent Hartree-Fock method with the SOP parametrization. A comparison with the previous predictions that were based on a non-selfconsistent approach is made. The existence of the {open_quotes}hyper-deformed shell closures{close_quotes} at the proton and neutron numbers Z=70 and N=100 and their very weak dependence on the rotational frequency is suggested; the corresponding single-particle energy gaps are predicted to play a role similar to that of the Z=66 and N=86 gaps in the super-deformed nuclei of the A {approximately} 150 mass range. Selfconsistent calculations suggest also that the A {approximately} 170 hyperdeformed structures have neglegible mass asymmetry in their shapes. Very importantly for the experimental studies, both the fission barriers and the {open_quotes}inner{close_quotes} barriers (that separate the hyperdeformed structures from those with smaller deformations) are predicted to be relatively high, up to the factor of {approximately}2 higher than the corresponding ones in the {sup 152}Dy superdeformed nucleus used as a reference.
International Nuclear Information System (INIS)
Chomaz, Ph.
2000-01-01
This document gathers the slides and their commentaries that have been presented at the conference 'physics and fundamental questions' by P. Chomaz. The author reviews the different quantum aspects of nuclei: tunnel effect, symmetries, magic numbers, wave functions, size, shapes and deformations. The author shows that nuclei are quantum objects of great complexity, their structures are not yet well understood and the study of exotic nuclei will continue bringing valuable information
Neutrino nucleosynthesis in supernovae: Shell model predictions
International Nuclear Information System (INIS)
Haxton, W.C.
1989-01-01
Almost all of the 3 · 10 53 ergs liberated in a core collapse supernova is radiated as neutrinos by the cooling neutron star. I will argue that these neutrinos interact with nuclei in the ejected shells of the supernovae to produce new elements. It appears that this nucleosynthesis mechanism is responsible for the galactic abundances of 7 Li, 11 B, 19 F, 138 La, and 180 Ta, and contributes significantly to the abundances of about 15 other light nuclei. I discuss shell model predictions for the charged and neutral current allowed and first-forbidden responses of the parent nuclei, as well as the spallation processes that produce the new elements. 18 refs., 1 fig., 1 tab
Pairing correlations in nuclei
International Nuclear Information System (INIS)
Baba, C.V.K.
1988-01-01
There are many similarities between the properties of nucleons in nuclei and electrons in metals. In addition to the properties explainable in terms of independent particle motion, there are many important co-operative effects suggesting correlated motion. Pairing correlation which leads to superconductivity in metals and several important properties in nuclei , is an exmple of such correlations. An attempt has been made to review the effects of pairing correlations in nuclei. Recent indications of reduction in pairing correlations at high angular momenta is discussed. A comparision between pairing correlations in the cases of nuclei and electrons in metals is attempted. (author). 20 refs., 10 figs
Spectroscopy of N approximately 82 nuclei near the proton drip line
International Nuclear Information System (INIS)
Daly, P.J.
1984-01-01
The yrast spectroscopy of Z>64 nuclei close to the proton drip line is discussed. This is a region of shell model nuclei in which high-spin excitations are accessible with heavy ion beams, and the occurrence of many isomers will facilitate future spectroscopic study of these nuclei to much higher spins that were observed in these investigations. The study of πhsub(11/2)sup(n) excitations in n=82 nuclei above 146 Gd provided particularly interesting results, since in certain respects their properties match shell model predictions better than those of jsup(n) states near traditional doubly magic nuclei. First results for N=81 nuclei above Z=64 were also reported, but much work remains to be done in the Z>64, N<82 quadrant
Nuclear masses, deformations and shell effects
International Nuclear Information System (INIS)
Hirsch, Jorge G; Barbero, César A; Mariano, Alejandro E
2011-01-01
We show that the Liquid Drop Model is best suited to describe the masses of prolate deformed nuclei than of spherical nuclei. To this end three Liquid Drop Mass formulas are employed to describe nuclear masses of eight sets of nuclei with similar quadrupole deformations. It is shown that they are able to fit the measured masses of prolate deformed nuclei with an RMS smaller than 750 keV, while for the spherical nuclei the RMS is, in the three cases, larger than 2000 keV. The RMS of the best fit of the masses of semi-magic nuclei is also larger than 2000 keV. The parameters of the three models are studied, showing that the surface symmetry term is the one which varies the most from one group of nuclei to another. In one model, isospin dependent terms are also found to exhibit strong changes. The inclusion of shell effects allows for better fits, which continue to be better in the prolate deformed nuclei region.
The Phebus FP thermal-hydraulic analysis with Melcor
International Nuclear Information System (INIS)
Akgane, Kikuo; Kiso, Yoshihiro; Fukahori, Takanori; Yoshino, Mamoru
1995-01-01
The severe accident analysis code MELCOR, version 1.8.2, has been applied for thermal-hydraulic pre-test analysis of the first test of the Phebus FP program (test FPT-0) to study the best test parameters and the applicability of the code. The Phebus FP program is an in-pile test program which has been planned by the French Commissariate a L'Energie Atomique and the Commission of the European Union. The experiments are being conducted by an international collaboration to study the release and transport of fission products (FPs) under conditions assumed to be the most representative of those that would occur in a severe accident. The Phebus FP test apparatus simulates a test bundle of an in-pile section, the circuit including the steam generator U-tubes and the containment. The FPT-0 test was designed to simulate the heat-up and subsequent fuel bundle degradation after a loss of coolant severe accident, using fresh fuel. Two options for fuel degradation models in MELCOR have been applied to fuel degradation behavior. the first model assumes that fuel debris will be formed immediately after the fuel support fails by cladding relocation due to the candling process. The other is the uncollapsed bare fuel pellets option, in which the fuel pellets remain standing in a columnar shape until the fuel reaches its melting point, even if the cladding has been relocated by candling. The thermal-hydraulic behaviors in the circuit and containment of Phebus FP are discussed herein. Flow velocities in the Phebus FP circuit are high in order to produce turbulent flow in a small diameter test pipe. The MELCOR calculation has shown that the length of the hot leg and steam generator are adequate to attain steam temperatures or 700 degrees C and 150 degrees C in the respective outlets. The containment atmosphere temperature and humidity derived by once through integral system calculation show that objective test conditions would be satisfied in the Phebus FP experiment
The Phebus FP thermal-hydraulic analysis with Melcor
Energy Technology Data Exchange (ETDEWEB)
Akgane, Kikuo; Kiso, Yoshihiro [Nuclear Power Engineering Corporation, Tokyo (Japan); Fukahori, Takanori [Hitachi Engineering Company, Ltd., Hitachi-shi Ibaraki-ken (Japan); Yoshino, Mamoru [Nuclear Engineering Ltd., Tosabori Nishi-ku (Japan)
1995-09-01
The severe accident analysis code MELCOR, version 1.8.2, has been applied for thermal-hydraulic pre-test analysis of the first test of the Phebus FP program (test FPT-0) to study the best test parameters and the applicability of the code. The Phebus FP program is an in-pile test program which has been planned by the French Commissariate a L`Energie Atomique and the Commission of the European Union. The experiments are being conducted by an international collaboration to study the release and transport of fission products (FPs) under conditions assumed to be the most representative of those that would occur in a severe accident. The Phebus FP test apparatus simulates a test bundle of an in-pile section, the circuit including the steam generator U-tubes and the containment. The FPT-0 test was designed to simulate the heat-up and subsequent fuel bundle degradation after a loss of coolant severe accident, using fresh fuel. Two options for fuel degradation models in MELCOR have been applied to fuel degradation behavior. the first model assumes that fuel debris will be formed immediately after the fuel support fails by cladding relocation due to the candling process. The other is the uncollapsed bare fuel pellets option, in which the fuel pellets remain standing in a columnar shape until the fuel reaches its melting point, even if the cladding has been relocated by candling. The thermal-hydraulic behaviors in the circuit and containment of Phebus FP are discussed herein. Flow velocities in the Phebus FP circuit are high in order to produce turbulent flow in a small diameter test pipe. The MELCOR calculation has shown that the length of the hot leg and steam generator are adequate to attain steam temperatures or 700{degrees}C and 150{degrees}C in the respective outlets. The containment atmosphere temperature and humidity derived by once through integral system calculation show that objective test conditions would be satisfied in the Phebus FP experiment.
Deformation and shape coexistence in medium mass nuclei
International Nuclear Information System (INIS)
Meyer, R.A.
1985-01-01
Emerging evidence for deformed structures in medium mass nuclei is reviewed. Included in this review are both nuclei that are ground state symmetric rotors and vibrational nuclei where there are deformed structures at excited energies (shape coexistence). For the first time, Nilsson configurations in odd-odd nuclei within the region of deformation are identified. Shape coexistence in nuclei that abut the medium mass region of deformation is also examined. Recent establishment of a four-particle, four-hole intruder band in the double subshell closure nucleus 96 Zr 56 is presented and its relation to the nuclear vibron model is discussed. Special attention is given to the N=59 nuclei where new data have led to the reanalysis of 97 Sr and 99 Zr and the presence of the [404 9/2] hole intruder state as isomers in these nuclei. The low energy levels of the N=59 nuclei from Z=38 to 50 are compared with recent quadrupole-phonon model calculations that can describe their transition from near-rotational to single closed shell nuclei. The odd-odd N=59 nuclei are discussed in the context of coexisting shape isomers based on the (p[303 5/2]n[404 9/2])2 - configuration. Ongoing in-beam (t,p conversion-electron) multiparameter measurements that have led to the determination of monopole matrix elements for even-even 42 Mo nuclei are presented, and these are compared with initial estimates using IBA-2 calculations that allow mixing of normal and cross subshell excitations. Lastly, evidence for the neutron-proton 3 S 1 force's influence on the level structure of these nuclei is discussed within the context of recent quadrupole-phonon model calculations. (Auth.)
From heavy nuclei to super-heavy nuclei; Des noyaux lourds aux super-lourds
Energy Technology Data Exchange (ETDEWEB)
Theisen, Ch
2003-01-01
The existence of super-heavy nuclei has been predicted nearly fifty years ago. Due to the strong coulomb repulsion, the stabilisation of these nuclei is possible only through shell effects. The reasons for this fragile stability, as well as the theoretical predictions concerning the position of the island of stability are presented in the first part of this lecture. In the second part, experiments and experimental techniques which have been used to synthesize or search for super-heavy elements are described. Spectroscopic studies performed in very heavy elements are presented in the following section. We close this lecture with techniques that are currently being developed in order to reach the superheavy island and to study the structure of very-heavy nuclei. (author)
International Nuclear Information System (INIS)
Klotz, G.
1991-01-01
The volume discuss nuclear structure of light and nuclei far from stability. The discussions took place in five sessions. In session 1 β decay, in session 2 nuclei near N=20, in session 3 radioactive ion beams' study with help of electromagnetic separators, in session 4 beta decay of light nuclei, in session 5 further papers were discussed in shell models, binding energy and chart of nuclides. (G.P.)
Structure of the drip line nuclei probed by separation energies
Czech Academy of Sciences Publication Activity Database
Dlouhý, Zdeněk
2006-01-01
Roč. 15, č. 7 (2006), s. 1471-1475 ISSN 0218-3013 Institutional research plan: CEZ:AV0Z10480505 Keywords : Neutron-rich nuclei * Shell- modell * Magic-number Subject RIV: BE - Theoretical Physics Impact factor: 0.810, year: 2006
Nuclei with exotic constituents
International Nuclear Information System (INIS)
Yamazaki, Toshimitsu.
1990-08-01
We discuss various interesting features in the behavior of exotic constituents of nuclei such as hyperons and mesons, in particular, with emphases on the aspect of exotic halos which are formed in general by short-range repulsion and long-range attraction. Specifically, Λ and Σ hypernuclei and pionic nuclei are discussed. (author)
International Nuclear Information System (INIS)
Foucher, R.
1979-01-01
If some β - emitters are particularly interesting to study in light, medium, and heavy nuclei, another (and also) difficult problem is to know systematically the properties of these neutron rich nuclei far from the stability line. A review of some of their characteristics is presented. How far is it possible to be objective in the interpretation of data is questioned and implications are discussed
International Nuclear Information System (INIS)
Arenhoevel, H.
1977-01-01
The field of baryon resonances in nuclei is reviewed. Theoretical developments and experimental evidence as well are discussed. Special emphasis is laid on electromagnetic processes for the two nucleon system. Some aspects of real isobars in nuclei are touched upon. (orig.) [de
International Nuclear Information System (INIS)
Szymanski, Z.; Berger, J.F.; Heenen, P.H.; Heyde, K.; Haas, B.; Janssens, R.; Paya, D.; Gogny, D.; Huber, G.; Bjoernholm, S.; Brack, M.
1991-01-01
The purpose of 1991 Joliot-Curie Summer School is to review the most advances in the understanding of the nuclei physics after the considerable progress in gamma spectroscopy. It covers the following topics: Highly and super-deformed nuclei, nuclear structures, mean-field approach and beyond, fission isomers, nuclear excitations with long lifetime and metal clusters
International Nuclear Information System (INIS)
Liu, L.C.
1987-01-01
The possibility of producing eta-mesic nuclei by the use of pions is discussed. If these nuclei are observed experimentally, then the binding energies of the eta in this new nuclear matter can be used to extract accurately the eta-N-N* coupling constant in a nucleus. The framework for these calculations is the coupled channel isobar model
Superheavy nuclei in the relativistic mean-field theory
International Nuclear Information System (INIS)
Lalazissis, G.A.; Ring, P.; Gambhir, Y.K.
1996-01-01
We have carried out a study of superheavy nuclei in the framework of the relativistic mean-field theory. Relativistic Hartree-Bogoliubov (RHB) calculations have been performed for nuclei with large proton and neutron numbers. A finite-range pairing force of Gogny type has been used in the RHB calculations. The ground-state properties of very heavy nuclei with atomic numbers Z=100-114 and neutron numbers N=154-190 have been obtained. The results show that in addition to N=184 the neutron numbers N=160 and N=166 exhibit an extra stability as compared to their neighbors. For the case of protons the atomic number Z=106 is shown to demonstrate a closed-shell behavior in the region of well deformed nuclei about N=160. The proton number Z=114 also indicates a shell closure. Indications for a doubly magic character at Z=106 and N=160 are observed. Implications of shell closures on a possible synthesis of superheavy nuclei are discussed. (orig.)
Rotational order–disorder structure of fluorescent protein FP480
International Nuclear Information System (INIS)
Pletnev, Sergei; Morozova, Kateryna S.; Verkhusha, Vladislav V.; Dauter, Zbigniew
2009-01-01
An analysis of the rotational order–disorder structure of fluorescent protein FP480 is presented. In the last decade, advances in instrumentation and software development have made crystallography a powerful tool in structural biology. Using this method, structural information can now be acquired from pathological crystals that would have been abandoned in earlier times. In this paper, the order–disorder (OD) structure of fluorescent protein FP480 is discussed. The structure is composed of tetramers with 222 symmetry incorporated into the lattice in two different ways, namely rotated 90° with respect to each other around the crystal c axis, with tetramer axes coincident with crystallographic twofold axes. The random distribution of alternatively oriented tetramers in the crystal creates a rotational OD structure with statistically averaged I422 symmetry, although the presence of very weak and diffuse additional reflections suggests that the randomness is only approximate
[(123)I]FP-CIT ENC-DAT normal database
DEFF Research Database (Denmark)
Tossici-Bolt, Livia; Dickson, John C; Sera, Terez
2017-01-01
BACKGROUND: [(123)I]FP-CIT is a well-established radiotracer for the diagnosis of dopaminergic degenerative disorders. The European Normal Control Database of DaTSCAN (ENC-DAT) of healthy controls has provided age and gender-specific reference values for the [(123)I]FP-CIT specific binding ratio...... quantifications methods, BRASS and Southampton, and explores the performance of the striatal phantom calibration in their harmonisation. RESULTS: BRASS and Southampton databases comprising 123 ENC-DAT subjects, from gamma cameras with parallel collimators, were reconstructed using filtered back projection (FBP......) and iterative reconstruction OSEM without corrections (IRNC) and compared against the recommended OSEM with corrections for attenuation and scatter and septal penetration (ACSC), before and after applying phantom calibration. Differences between databases were quantified using the percentage difference...
Spin Modes in Nuclei and Nuclear Forces
International Nuclear Information System (INIS)
Suzuki, Toshio; Otsuka, Takaharu
2011-01-01
Spin modes in stable and unstable exotic nuclei are studied and important roles of tensor and three-body forces on nuclear structure are discussed. New shell model Hamiltonians, which have proper tensor components, are shown to explain shell evolutions toward drip-lines and spin properties of both stable and exotic nuclei, for example, Gamow-Teller transitions in 12 C and 14 C and an anomalous M1 transition in 17 C. The importance and the necessity of the repulsive monopole corrections in isospin T = 1 channel to the microscopic two-body interactions are pointed out. The corrections are shown to lead to the proper shell evolutions in neutron-rich isotopes. The three-body force, in particular the Fujita-Miyazawa force induced by Δ excitations, is pointed out to be responsible for the repulsive corrections among the valence neutrons. The important roles of the three-body force on the energies and transitions in exotic oxygen and calcium isotopes are demonstrated.
FP 6 EU - COVERS. Coordination action - VVER safety research
International Nuclear Information System (INIS)
Vasa, I.
2008-01-01
In this work research program of the European Union FP 6 - COVERS coordinated by the NRI Rez is presented. COVERS is designed to improve professional and communication environment in the specific area covering all aspects of safe and reliable operation of nuclear power plants with VVER-440 and VVER-1000 reactors. Project Consortium is composed of 26 research and development, engineering and technical support organisations of European VVER-operating and other EU and non-EU countries.
International Nuclear Information System (INIS)
Goethem, G. van; Zurita, A.; Manolatos, P.; Casalta, S.
2004-01-01
An overview is given of the most important achievements of the research programme co-financed by the European Union (EU) in the area of LWR safety over the FP-4 and FP-5 periods from the end-users point of view. The end-users are: the contracting organisations (i.e. utilities and associated engineering companies, regulatory bodies and associated technical safety organisations, manufacturing industry and associated services), the non-contracting organisations (including decision makers and opinion leaders) and the European Commission. Besides Community research strategy and programme implementation aspects in general, this paper is focusing on the S/T achievements obtained by multi-partner projects in the - 7 clusters of multi-partner projects in Euratom FP-4 (1994-1998): AGE for structural ageing, INV and EXV for in-vessel core degradation and ex-vessel molten corium coolability, ST for radiological source term, CONT for containment integrity, AMM for accident management measures and INNO for innovative safety features - the total cost of the 67 multipartner projects comprised in this Community research was Euro 71.3 million, out of which Euro 35.9 million was contributed by the EU budget - 3 clusters of multi-partner projects in Euratom FP-5 (1998-2002): PLEM for plant life extension and management; SAM for severe accident management and EVOL for evolutionary safety concepts - the total cost of the 71 multipartner projects comprised in this Community research is Euro 85.4 million, out of which Euro 43.5 million is contributed by the EU budget. The objectives of this Community research are discussed and a number of FP-4 and FP-5 projects are selected to demonstrate to what extent the proposed objectives were indeed met. Besides technological requirements, socio-economic aspects are becoming increasingly important due to the level of public and political acceptance and to the economic pressure of deregulated electricity markets; this is also discussed. Finally the
Basic Evidence and Properties of Single-Particle States in Nuclei
Energy Technology Data Exchange (ETDEWEB)
Cindro, N. [Institute ' ' Rudjer Boskovic' ' , Zagreb, Yugoslavia (Croatia)
1970-07-15
1. Introduction: the shell-model orbitals; 2. Information about single-particle orbitals: a critical evaluation; 3. Experimental evidence: 3.1. The lead region; 3.2. The calcium region; 3.3. Nuclei far from closed shells; 4. Conclusion. (author)
Collaboration on HiPER EU FP7 Project
International Nuclear Information System (INIS)
Rhee, Yong Joo; Han, Jae Min; Nam, Sung Mo; Chung, Chin Man; Lim, Chang Hwan; Cha, Yong Ho; Kwon, Duck Hee
2011-06-01
European Union started the HiPER project to establish a laser fusion research facility for energy production in Europe. Feasibility study and conceptual design has been performed for 2 years from 2005 and based on this study HiPER preparatory phase project has been proposed in 2007 as a EU FP7 project by 10 European countries and approved by EC. The project started in April of 2008 officially for 36 months until April of 2011. HiPER is a unique pure civilian laser fusion research facility and supported by ESFRI road map. KAERI has been participating HiPER from the feasibility study phase and still collaborating with HiPER EU FP7 project officially with the funding from the Korean government. Through this technical collaboration, participation in the joint experiments at large laser facilities has been possible and infrastructure of scientists exchange has been established Although the EU FP7 HiPER preparatory phase project ends at April of 2011 (actually it is extended until 2013 without further budget allocation fm EC) the total HiPER programme is planned to continue for more than 10 more years until the construction and commission of the fusion reactor. And KAERI also continue to participate in the HiPER programme in the future until the end of the programme
Energy Technology Data Exchange (ETDEWEB)
Lundkvist, Camilla; Halldin, Christer; Ginovart, Nathalie; Swahn, Carl-Gunnar; Farde, Lars
1997-10-01
{beta}-CIT-FP [N-(3-fluoropropyl)-2{beta}-carbomethoxy-3{beta}-(4-iodophenyl)nortropane] is a cocaine analogue with high affinity for the dopamine transporter. Positron emission tomography (PET) studies with [O-methyl-{sup 11}C]{beta}-CIT-FP ([{sup 11}C]{beta}-CIT-FP) has shown that equilibrium conditions were approached but, however, not reached at the end of measurement. Moreover, metabolite studies of [{sup 11}C]{beta}-CIT-FP in monkey plasma demonstrated a lipophilic-labelled metabolite that may enter the brain. We therefore labelled {beta}-CIT-FP with fluorine-18 in a position that may avoid the formation of labelled lipophilic metabolites. The more long-lived radionuclide ({sup 18}F) was used to allow for measurements over longer time. [N-fluoropropyl-{sup 18}F]{beta}-CIT-FP ([{sup 18}F]{beta}-CIT-FP) was prepared by N-alkylation of nor-{beta}-CIT with [{sup 18}F]fluoropropyl bromide. PET studies were performed in cynomolgus monkeys. [{sup 18}F]{beta}-CIT-FP entered the brain rapidly. There was a high concentration of radioactivity in the striatum and much lower in the thalamus, neocortex, and cerebellum. The striatum-to-cerebellum ratio was about 5 at time of transient equilibrium, which occurred after 60 to 100 min. After pretreatment with GBR 12909, radioactivity in the striatum was markedly reduced, thus indicating specific [{sup 18}F]{beta}-CIT-FP binding to the dopamine transporter. The fraction of unchanged [{sup 18}F]{beta}-CIT-FP determined by HPLC was 10-15% after 140 min. No lipophilic labelled metabolites were detected. The absence of measurable lipophilic labelled metabolites and the occurrence of transient equilibrium within the time of the PET measurement indicate that [{sup 18}F]{beta}-CIT-FP is superior to [{sup 11}C]{beta}-CIT-FP as a PET radioligand for quantification of the dopamine transporter in the human brain.
Spectroscopic Studies of Exotic Nuclei at ISOLDE
2002-01-01
Experiment IS50 is designed to: a) Investigate the full range of the @b strength function of heavy (A~$>$~48)~K nuclei b)~Study the decay of isomeric states in n-deficient bromine nuclei (A~=~72 and 70). The heavy K isotopes appeared to have complex decay schemes, including feeding by the @b-decay of levels having open neutron channels (Beta decay energy Q(@b) exceeds neutron binding energy S^n); in addition, a large fraction of the delayed transitions populate excited levels in the daughter nuclei. The allowed @b-decay selects states in the daughter nucleus with wave functions having a large overlap with the initial state. Hence, the @b strength functions, deduced from these deca reveal simple structures correlated to the particle-hole excitation energies in the Ca nuclei. These results are valuable for the application of the shell-model calculations far from stability. The delayed neutron spectra are measured with a large area curved scintillator in coincidence either with high resolution Ge(Li) detectors, ...
Nuclear structure investigations on spherical nuclei
International Nuclear Information System (INIS)
Heisenberg, J.; Calarco, J.; Dawson, J.; Hersman, F.W.
1989-09-01
This report discusses the following topics: electron scattering studies on spherical nuclei; electron scattering from collective states in deformed nuclei; proton and pion scattering studies; 12 C(e,e'p) and 16 O(e,e'p); 12 C(e,e'α) and 16 O(e,e'α); studies at high q at Bates; measurements with rvec e at Bates; 12 C(γ,p); future directions in giant resonance studies; proton knockout from 16 O; quasielastic studies at Bates; triple coincidence studies of nuclear correlations; contributions to (e,e'2p) at KIKHEF; contributions to instrumentation at CEBAF; instrumentation development at UNH; the Bates large acceptance spectrometer toroid; shell model and core polarization calculations; and the relativistic nuclear model
Collective properties of drip-line nuclei
Energy Technology Data Exchange (ETDEWEB)
Hamamoto, I. [Univ. of Lund (Sweden); Sagawa, H. [Univ. of Aizu, Fukushima (Japan)
1996-12-31
Performing the spherical Hartree-Fock (HF) calculations with Skyrme interactions and, then, using RPA solved in the coordinate space with the Green`s function method, the authors have studied the effect of the unique shell structure as well as the very low particle threshold on collective modes in drip line nuclei. In this method a proper strength function in the continuum is obtained, though the spreading width of collective modes is not included. They have examined also one-particle resonant states in the obtained HF potential. Unperturbed particle-hole (p-h) response functions are carefully studied, which contain all basic information on the exotic behaviour of the RPA strength function in drip line nuclei.
Realistic microscopic level densities for spherical nuclei
International Nuclear Information System (INIS)
Cerf, N.
1994-01-01
Nuclear level densities play an important role in nuclear reactions such as the formation of the compound nucleus. We develop a microscopic calculation of the level density based on a combinatorial evaluation from a realistic single-particle level scheme. This calculation makes use of a fast Monte Carlo algorithm allowing us to consider large shell model spaces which could not be treated previously in combinatorial approaches. Since our model relies on a microscopic basis, it can be applied to exotic nuclei with more confidence than the commonly used semiphenomenological formuals. An exhaustive comparison of our predicted neutron s-wave resonance spacings with experimental data for a wide range of nuclei is presented
The structure of nuclei far from stability
International Nuclear Information System (INIS)
Zganjar, E.F.
1993-01-01
Studies on nuclei near Z=82 contributed to the establishment of a new region of nuclear deformation and a new class of nuclear structure at closed shells. A important aspect of this work is the establishment of the connection between low-lying 0 + states in even endash even nuclei and the occurrence of shape coexistence in the odd-mass neighbors (E0 transitions in 185 Pt, shape coexistence in 184 Pt and 187 Au). A new type of picosecond lifetime measurement system capable of measuring the lifetime of states that decay only by internal conversion was developed and applied to the 186,188 Tl decay to determine the lifetime of the 0 2 + and 2 2 + deformed states in 186,188 Hg. A search for the population of superdeformed states in 192 Hg by the radioactive decay of 192 Tl was accomplished by using a prototype internal pair formation spectrometer
International Nuclear Information System (INIS)
Grange, P.; Mathiot, J.F.; Roy-Stephan, M.; Frascaria, R.; Gales, S.
1990-01-01
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 [fr
Dynamic polarisation of nuclei
International Nuclear Information System (INIS)
Borghini, M.; Abragam, A.
1961-01-01
In magnetic fields of about 13000 gauss, at a temperature of 1.5 deg. K, in samples of about 2 mm 3 , we have obtained by the 'solid effect' (application of a magnetic field at an appropriate frequency around 35000 MHz), nuclear polarizations /I of a few percent: 19 per cent for hydrogen nuclei in single crystals of La 2 Mg 3 (NO 3 ) 12 , 24H 2 O; 5 per cent for hydrogen nuclei in polystyrene; 6 per cent for fluorine nuclei in single crystals of LiF. (author) [fr
Energy Technology Data Exchange (ETDEWEB)
Furusawa, Shun; Yamada, Shoichi [Advanced Research Institute for Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555 (Japan); Sumiyoshi, Kohsuke [Numazu College of Technology, Ooka 3600, Numazu, Shizuoka 410-8501 (Japan); Suzuki, Hideyuki, E-mail: furusawa@heap.phys.waseda.ac.jp [Faculty of Science and Technology, Tokyo University of Science, Yamazaki 2641, Noda, Chiba 278-8510 (Japan)
2013-08-01
We construct new equations of state for baryons at subnuclear densities for the use in core-collapse simulations of massive stars. The abundance of various nuclei is obtained together with thermodynamic quantities. A model free energy is constructed, based on the relativistic mean field theory for nucleons and the mass formula for nuclei with the proton number up to {approx}1000. The formulation is an extension of the previous model, in which we adopted the liquid drop model to all nuclei under the nuclear statistical equilibrium. We reformulate the new liquid drop model so that the temperature dependences of bulk energies could be taken into account. Furthermore, we extend the region in the nuclear chart, in which shell effects are included, by using theoretical mass data in addition to experimental ones. We also adopt a quantum-theoretical mass evaluation of light nuclei, which incorporates the Pauli- and self-energy shifts that are not included in the ordinary liquid drop model. The pasta phases for heavy nuclei are taken into account in the same way as in the previous model. We find that the abundances of heavy nuclei are modified by the shell effects of nuclei and temperature dependence of bulk energies. These changes may have an important effect on the rates of electron captures and coherent neutrino scatterings on nuclei in supernova cores. The abundances of light nuclei are also modified by the new mass evaluation, which may affect the heating and cooling rates of supernova cores and shocked envelopes.
International Nuclear Information System (INIS)
Furusawa, Shun; Yamada, Shoichi; Sumiyoshi, Kohsuke; Suzuki, Hideyuki
2013-01-01
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 ∼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
Furusawa, Shun; Sumiyoshi, Kohsuke; Yamada, Shoichi; Suzuki, Hideyuki
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 ~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.
Statistics and the shell model
International Nuclear Information System (INIS)
Weidenmueller, H.A.
1985-01-01
Starting with N. Bohr's paper on compound-nucleus reactions, we confront regular dynamical features and chaotic motion in nuclei. The shell-model and, more generally, mean-field theories describe average nuclear properties which are thus identified as regular features. The fluctuations about the average show chaotic behaviour of the same type as found in classical chaotic systems upon quantisation. These features are therefore generic and quite independent of the specific dynamics of the nucleus. A novel method to calculate fluctuations is discussed, and the results of this method are described. (orig.)
International Nuclear Information System (INIS)
Karpeshin, F. F.
2002-01-01
Main principles of the resonance effect arising in the electron shells in interaction of the nuclei with electromagnetic radiation are analyzed and presented in the historical aspect. Principles of NEET are considered from a more general position, as compared to how this is usually presented. Characteristic features of NEET and its reverse, TEEN, as internal conversion processes are analyzed, and ways are offered of inducing them by laser radiation. The ambivalent role of the Pauli exclusion principles in NEET and TEEN processes is investigated.
The Structure of Nuclei Far from Stability
International Nuclear Information System (INIS)
Zganjar, E.F.
1999-01-01
From among a number of important nuclear structure results that have emerged from our research program during the past few years, two stand out as being of extra significance. These are: (a) the identification of a diabatic coexisting structure in 187 Au which arises solely from differences in proton occupation of adjacent oscillator shells, and (b) the realization of a method for estimating EO strength in nuclei and the resulting prediction that the de-excitation of superdeformed bands may proceed, in some cases, by strong EO transitions
Exploring the Physics of Unstable Nuclei
Volya, Alexander
In this presentation the Continuum Shell Model (CSM) approach is advertised as a powerful theoretical tool for studying physics of unstable nuclei. The approach is illustrated using 17O as an example, which is followed by a brief presentation of the general CSM formalism. The successes of the CSM are highlighted and references are provided throughout the text. As an example, the CSM is applied perturbatively to 20O allowing one to explore the effects of continuum on positions of weakly bound states and low-lying resonances, as well as to discern some effects of threshold discontinuity.
Exploring the physics of unstable nuclei
International Nuclear Information System (INIS)
Volya, Alexander
2015-01-01
In this presentation the Continuum Shell Model (CSM) approach is advertised as a powerful theoretical tool for studying physics of unstable nuclei. The approach is illustrated using 17 O as an example, which is followed by a brief presentation of the general CSM formalism. The successes of the CSM are highlighted and references are provided throughout the text. As an example, the CSM is applied perturbatively to 20 O allowing one to explore the effects of continuum on positions of weakly bound states and low-lying resonances, as well as to discern some effects of threshold discontinuity. (author)
International Nuclear Information System (INIS)
Roberts, R.G.
1984-11-01
The paper concerns the behaviour of quarks in nuclei. Confinement size changes and dynamical rescaling; A dependence; low-x region; gluons and confinement size; and nucleons in a nucleus; are all discussed. (U.K.)
International Nuclear Information System (INIS)
Mackintosh, R.S.
1977-01-01
For the class of nuclei which are 'strongly deformed' it is possible to introduce the idea of an empirically measurable static nuclear shape. The limitations of this concept as applied to nuclei (fundamentally quantum-mechanical objects) are discussed. These are basically the limitations of the rotational model which must be introduced in order to define and measure nuclear shape. A unified discussion of the ways in which the shape has been parametrized is given with emphasis on the fact that different parametrizations correspond to different nuclear structures. Accounts of the various theoretical procedures for calculating nuclear shapes and of the interaction between nuclear shapes and nuclear spectroscopy are given. A coherent account of a large subset of nuclei (strongly deformed nuclei) can be given by means of a model in which the concept of nuclear shape plays a central role. (author)
International Nuclear Information System (INIS)
Aaberg, S.; Uhrenholt, H.
2009-01-01
We study the structure of nuclei in the energy region between the ground state and the neutron separation energy, here called warm nuclei. The onset of chaos in the nucleus as excitation energy is increased is briefly reviewed. Chaos implies fluctuations of energies and wave functions qualitatively the same for all chaotic nuclei. On the other hand, large structure effects are seen, e.g. in the level-density function at same excitation energies. A microscopic model for the level density is reviewed and we discuss effects on structure of the total level-density function, parity enhancement, and the spin distribution function. Comparisons to data are performed at the neutron separation energy for all observed nuclei, and structure of the level-density function for a few measured cases. The role of structure effects in the level-density function for fission dynamics is exemplified.
International Nuclear Information System (INIS)
Guerreau, D.
1993-01-01
A review is made of the present status concerning the production of nuclei above 5 MeV temperature. Considerable progress has been made recently on the understanding of the formation and the fate of such hot nuclei. It appears that the nucleus seems more stable against temperature than predicted by static calculations. However, the occurrence of multifragment production at high excitation energies is now well established. The various experimental features of the fragmentation process are discussed. (author) 59 refs., 12 figs
An attempt for revision of JNDC FP decay data file
International Nuclear Information System (INIS)
Katakura, Jun-ichi; Matsumoto, Zyun-itiro; Akiyama, Masatsugu; Yoshida, Tadashi; Nakasima, Ryozo.
1984-06-01
Some improvement of JNDC FP Decay Data File is tried by reexamining the decay scheme for several nuclides, since slight discrepancies are seen in detailed comparison of decay powers. As a results, it is found that the average beta- and gamma-energies should be modified for 88 Rb and 143 La among the nuclides reexamined in the present study. The JNDC file modified in 88 Rb and 143 La gives better agreement in most cases with experiments than the original JNDC file for cooling times longer than a few thousands seconds. However, the discrepancy for cooling times from a few hundreds to about 1500 seconds still remains. (author)
Instrument development in support of Falcon and Phebus-FP
International Nuclear Information System (INIS)
Bowsher, B.R.; Brunning, J.
1992-12-01
This review has been undertaken to identify various on-line instruments and post-test analytical techniques that may improve the quality of data from both the Falcon Integral Test Programme and Phebus-FP. Particular emphasis is placed on the use of in-situ techniques to provide mass-based data on the aerodynamic properties of the aerosol and fission product-surface interactions. The principles of the following techniques are reviewed: cascade impactors, tapered element oscillating microbalance, condensation nucleus counter, Knudsen cell mass spectrometry, diffuse reflectance infrared Fourier transform spectrometry and secondary-ion mass spectrometry. These methods are currently being used in the Falcon experimental programme. (author)
Challenges in Implementing FP7 Projects in the Public Institutions
Directory of Open Access Journals (Sweden)
Viorel VULTURESCU
2012-06-01
Full Text Available National Authority for Scientific Research (ANCS and Executive Unit for Higher Education, Research and Development and Innovation Funding (UEFISCDI participate to several projects funded under the Framework Programmes, since 1998. The staff from each the two organisations participating in projects are merely the same, typically from “international cooperation” departments. In each of the two organisations, dedicated teams were set and a distinct specialization emerged. In this respect, dedicated procedures and good practices in project management were developed. Even the Framework Programs had different structures and the focused was different (e.g. knowledge creation, EU problem solving, scientific support for policies and programs, etc., the funding instruments (projects were not radically different from a Framework Program to another, so the staff could gain experience in managing this type of projects. Experience and expertise gained during this long period of time led to definition of a general framework within the two institutions and setting up of a general guideline for participation to this type of projects. The main dimensions of this framework are: project team organization, project management process, managing results and risk, organisational framework, good practices, factors which ensure success in project implementation.The paper presents a specific framework for FP 7 project implementation and how this framework is applied by both organisations, a set of rules and procedures that should be followed by any organisation, in particular governmental ones, participating in FP 7 projects and a set of good practices developed by ANCS and UEFISCDI.
International Nuclear Information System (INIS)
Chrien, R.E.
1982-01-01
A brief history of the discovery of hypernuclei is given and some recent hypernuclei studies are described. Topics include the study of p-shell hypernuclei, 12 C (K - , π - ) experiment, and hypernuclear gamma rays. 13 references
Synthesis and radioactive properties of the heaviest nuclei
International Nuclear Information System (INIS)
Oganesyan, Yu.Ts.
1996-01-01
Experimental investigations on the synthesis and study of properties of faraway transactinide elements confirm the predictions of macro-microscopic theory on the existence of closed shells in the region of heavy deformed nuclei. It has been demonstrated experimentally that nuclear structure plays a decisive role in the stability of superheavy nuclides. Based on the experimental confirmation of the main provisions of the theory and after the introduction of a necessary correction into the calculation the properties of heavier nuclides in the region of spherical shells Z=114 and N=180-184 have been predicted. Here a substantial increase in the stability of nuclei is also expected. All the nuclei synthesized by now, were obtained in fusion reactions with a formation of a compound nucleus, the transition of which to the ground state takes place with the emission of neutrons and gamma-rays. Both the reactions of cold and hot fusion of nuclei can be used for the synthesis of new nuclei. Nevertheless, new experimental data on the fusion mechanism are required, since a number of theoretical descriptions of the fusion dynamics of complex nuclear systems need a substantial revising. One can assume that the reactions of the type 244 Pu, 248 Cm + 48 Ca are still within the current potential of the accelerators and experimental technique. This potential, nevertheless, is still to be implemented. 37 refs., 6 figs
Reactions with fast radioactive beams of neutron-rich nuclei
Energy Technology Data Exchange (ETDEWEB)
Aumann, T. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany)
2005-11-01
The neutron dripline has presently been reached only for the lightest nuclei up to the element oxygen. In this region of light neutron-rich nuclei, scattering experiments are feasible even for dripline nuclei by utilizing high-energy secondary beams produced by fragmentation. In the present article, reactions of high-energy radioactive beams will be exemplified using recent experimental results mainly derived from measurements of breakup reactions performed at the LAND and FRS facilities at GSI and at the S800 spectrometer at the NSCL. Nuclear and electromagnetically induced reactions allow probing different aspects of nuclear structure at the limits of stability related to the neutron-proton asymmetry and the weak binding close to the dripline. Properties of the valence-neutron wave functions are studied in the one-neutron knockout reaction, revealing the changes of shell structure when going from the beta-stability line to more asymmetric loosely bound neutron-rich systems. The vanishing of the N=8 shell gap for neutron-rich systems like {sup 11}Li and {sup 12}Be, or the new closed N=14, 16 shells for the oxygen isotopes are examples. The continuum of weakly bound nuclei and halo states can be studied by inelastic scattering. The dipole response, for instance, is found to change dramatically when going away from the valley of stability. A redistribution of the dipole strength towards lower excitation energies is observed for neutron-rich nuclei, which partly might be due to a new collective excitation mode related to the neutron-proton asymmetry. Halo nuclei in particular show strong dipole transitions to the continuum at the threshold, being directly related to the ground-state properties of the projectile. Finally, an outlook on future experimental prospects is given. (orig.)
Reactions with fast radioactive beams of neutron-rich nuclei
International Nuclear Information System (INIS)
Aumann, T.
2005-11-01
The neutron dripline has presently been reached only for the lightest nuclei up to the element oxygen. In this region of light neutron-rich nuclei, scattering experiments are feasible even for dripline nuclei by utilizing high-energy secondary beams produced by fragmentation. In the present article, reactions of high-energy radioactive beams will be exemplified using recent experimental results mainly derived from measurements of breakup reactions performed at the LAND and FRS facilities at GSI and at the S800 spectrometer at the NSCL. Nuclear and electromagnetically induced reactions allow probing different aspects of nuclear structure at the limits of stability related to the neutron-proton asymmetry and the weak binding close to the dripline. Properties of the valence-neutron wave functions are studied in the one-neutron knockout reaction, revealing the changes of shell structure when going from the beta-stability line to more asymmetric loosely bound neutron-rich systems. The vanishing of the N=8 shell gap for neutron-rich systems like 11 Li and 12 Be, or the new closed N=14, 16 shells for the oxygen isotopes are examples. The continuum of weakly bound nuclei and halo states can be studied by inelastic scattering. The dipole response, for instance, is found to change dramatically when going away from the valley of stability. A redistribution of the dipole strength towards lower excitation energies is observed for neutron-rich nuclei, which partly might be due to a new collective excitation mode related to the neutron-proton asymmetry. Halo nuclei in particular show strong dipole transitions to the continuum at the threshold, being directly related to the ground-state properties of the projectile. Finally, an outlook on future experimental prospects is given. (orig.)
Advanced modeling of reaction cross sections for light nuclei
International Nuclear Information System (INIS)
Resler, D.A.
1991-01-01
The shell model/R-matrix technique of calculating nuclear reaction cross sections for light projectiles incident on light nuclei is discussed, particularly in the application of the technique to thermonuclear reactions. Details are presented on the computational methods for the shell model which display how easily the calculations can be performed. Results of the shell model/R-matrix technique are discussed as are some of the problems encountered in picking an appropriate nucleon-nucleon interaction for the large model spaces which must be used for current problems. The status of our work on developing an effective nucleon-nucleon interaction for use in large-basis shell model calculations is presented. This new interaction is based on a combination of global constraints and microscopic nuclear data. 23 refs., 6 figs., 2 tabs
Multifragmentation of hot nuclei
International Nuclear Information System (INIS)
Tamain, B.
1990-10-01
It is difficult to deposit a large amount (∼ 1 Gev) of excitation energy into a nucleus. And if one wants to deposit large excitation energy values, the best way consists of shooting a given target nucleus with several nucleons, which can be achieved by using intermediate energy (10-100 MeV/nucleon) heavy ions. Such very excited objects were named hot nuclei. The study of hot nuclei has been undertaken only for 7 years because intermediate energy heavy ion facilities were not available before. The game is then to determine the decay properties of such nuclei, their limits of existence. Their study is connected with general properties of nuclear matter: namely its equation of state. Of special interest, is the onset of a new decay mechanism: multifragmentation, which is the non-sequential disassembly of a hot nucleus into several light nuclei (often called intermediate-mass fragments or IMF) or particles. This paper, shows how this mechanism can reflect fundamental properties of nuclear matter, but also how its experimental signature is difficult to establish. Multifragmentation has also been studied by using very energetic projectiles (protons and heavy ions) in the relativistic or ultra-relativistic region. The multifragmentation question of hot nuclei is far from being solved. One knows that IMF production increases when the excitation energy brought into a system is strongly increased, but very little is known about the mechanisms involved and a clear onset for multifragmentation is not established
International Nuclear Information System (INIS)
Schramm, D.N.
1995-01-01
Primordial nucleosynthesis has established itself as one of the three pillars of Big Bang cosmology. Many of the Big Bang Nucleosynthesis reactions involve unstable nuclei. Hence there is a tight relationship hetween the subject of this conference and cosmology. The prime role of unstable nuclei in cosmology is related to lithium synthesis and the lack of cosmological synthesis of Be and B. These nuclei will thus be focused upon. Nucleosynthesis involves comparing calculated abundances with observed abundances. In general, abundance determinations are dominated by systematic rather than statistical errors, and work on bounding systematics is crucial. The quark-hadron inspired inhomogeneous calculations now unanimously agree that only relatively small variations in Ω b are possible vis-a-vis the homogeneous model; hence the robustness of Ω b ∼0.05 is now apparent. (These calculations depend critically on unstable nuclei.) The above argues that the bulk of the baryons in the universe are not producing visible light. A comparison with the ROSAT cluster data is also shown to be consistent with the standard BBN model. Ω b ∼1 seems to be definitely excluded, so if Ω TOTAL =1, as some recent observations may hint, then non-baryonic dark matter is required. The implications of the recently reported halo microlensing events are discussed. In summary, it is argued that the physics of unstable nuclei affects the fundamental dark matter argument. ((orig.))
Validity of the broken-pair approximation for N = 50, even-A nuclei
International Nuclear Information System (INIS)
Haq, S.; Gambhir, Y.K.
1977-01-01
The validity of the broken-pair approximation as an approximation to the seniority shell model is investigated. The results of the broken-pair approximation and the seniority shell model, obtained by employing identical input information (single-particle levels and their energies, effective two-body matrix elements, 88 Sr inert core) for N = 50, even-A nuclei are compared. A close agreement obtained between the calculated broken-pair approximation and the seniority shell model energies for 90 Zr, 92 Mo, 94 Ru, and 96 Pd nuclei and large (95--100 %) overlaps between the broken-pair approximation and the senority shell model wave functions for 92 Mo, demonstrates the validity of the broken-pair approximation in this region and in general its usefulness as a good approximation to the seniority shell model
No-Core Shell Model and Reactions
International Nuclear Information System (INIS)
Navratil, P; Ormand, W E; Caurier, E; Bertulani, C
2005-01-01
There has been a significant progress in ab initio approaches to the structure of light nuclei. Starting from realistic two- and three-nucleon interactions the ab initio no-core shell model (NCSM) can predict low-lying levels in p-shell nuclei. It is a challenging task to extend ab initio methods to describe nuclear reactions. In this contribution, we present a brief overview of the NCSM with examples of recent applications as well as the first steps taken toward nuclear reaction applications. In particular, we discuss cross section calculations of p+ 6 Li and 6 He+p scattering as well as a calculation of the astrophysically important 7 Be(p, γ) 8 B S-factor
Two-proton knockout on neutron-rich nuclei
International Nuclear Information System (INIS)
Bazin, D.; Brown, B.A.; Campbell, C.M.; Church, J.A.; Dinca, D.C.; Enders, J.; Gade, A.; Glasmacher, T.; Hansen, P.G.; Mueller, W.F.; Olliver, H.; Perry, B.C.; Sherrill, B.M.; Terry, J.R.; Tostevin, J.A.
2004-01-01
Two-proton knockout reactions on neutron-rich nuclei [Phys. Rev. Lett. 91 (2003) 012501] have been studied in inverse kinematics at intermediate energy. Strong evidence that the two-proton removal from a neutron-rich system proceeds as a direct reaction is presented, together with a preliminary theoretical discussion of the partial cross sections based on eikonal reaction theory and the many-body shell model. They show that this reaction can be used to characterize the wave functions of the projectiles and holds great promise for the study of neutron-rich nuclei
International Nuclear Information System (INIS)
Clark, R.M.
2004-01-01
It has been suggested that a change of nuclear shape may be described in terms of a phase transition and that specific nuclei may lie close to the critical point of the transition. Analytical descriptions of such critical-point nuclei have been introduced recently and they are described briefly. The results of extensive searches for possible examples of critical-point behavior are presented. Alternative pictures, such as describing bands in the candidate nuclei using simple ΔK = 0 and ΔK = 2 rotational-coupling models, are discussed, and the limitations of the different approaches highlighted. A possible critical-point description of the transition from a vibrational to rotational pairing phase is suggested
Shell model in large spaces and statistical spectroscopy
International Nuclear Information System (INIS)
Kota, V.K.B.
1996-01-01
For many nuclear structure problems of current interest it is essential to deal with shell model in large spaces. For this, three different approaches are now in use and two of them are: (i) the conventional shell model diagonalization approach but taking into account new advances in computer technology; (ii) the shell model Monte Carlo method. A brief overview of these two methods is given. Large space shell model studies raise fundamental questions regarding the information content of the shell model spectrum of complex nuclei. This led to the third approach- the statistical spectroscopy methods. The principles of statistical spectroscopy have their basis in nuclear quantum chaos and they are described (which are substantiated by large scale shell model calculations) in some detail. (author)
Buckling tests of sandwich cylindrical shells with and without cut-outs
Bisagni, C.; Davidson, B.D.; Czabaj, M.W.; Ratcliffe, J.G.
2016-01-01
The results of buckling tests performed during the project DESICOS funded by the European Commission in the FP7 Programme are here presented. The tested structures are sandwich cylindrical shells that consist of reduced models of a component of the Ariane 5 launcher: the Dual Launch System. In
International Nuclear Information System (INIS)
Walecka, J.D.
1983-01-01
Nuclei provide systems where the strong, electomagnetic, and weak interactions are all present. The current picture of the strong interactions is based on quarks and quantum chromodynamics (QCD). The symmetry structure of this theory is SU(3)/sub C/ x SU(2)/sub W/ x U(1)/sub W/. The electroweak interactions in nuclei can be used to probe this structure. Semileptonic weak interactions are considered. The processes under consideration include beta decay, neutrino scattering and weak neutral-current interactions. The starting point in the analysis is the effective Lagrangian of the Standard Model
International Nuclear Information System (INIS)
Rho, M.; CEA Centre d'Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette
1983-01-01
Some features of quark degrees of freedom in nuclei are discussed in the light of recent developments in QCD. The principal aim of this talk is to propose, and give a tentative support to, the motion that one can study through nuclear matter different facets of the vacuum structure implied by quantum chromodynamics (QCD). This will be done using the recent (exciting) results obtained in particle physics, in particular lattice gauge calculations. Relevance of this aspect of problem to quark degrees of freedom as well as meson degrees of freedom in nuclei will be discussed. (orig.)
Disintegration of comet nuclei
Ksanfomality, Leonid V.
2012-02-01
The breaking up of comets into separate pieces, each with its own tail, was seen many times by astronomers of the past. The phenomenon was in sharp contrast to the idea of the eternal and unchangeable celestial firmament and was commonly believed to be an omen of impending disaster, especially for comets with tails stretching across half the sky. It is only now that we have efficient enough space exploration tools to see comet nuclei and even - in the particular case of small comet Hartley-2 in 2010 - to watch their disintegration stage. There are also other suspected candidates for disintegration in the vast family of comet nuclei and other Solar System bodies.
International Nuclear Information System (INIS)
2002-01-01
The present collection of letters from JINR, Dubna, contains seven separate records on kinematic separation and mass analysis of heavy recoiling nuclei, dynamical effects prior to heavy ion fusion, VACTIV-DELPHI graphical dialog based program for the analysis of gamma-ray spectra, irradiation of nuclear emulsions in relativistic beams of 6 He and 3 H nuclei, optical and structural investigations of PLZT x/65/35 (x = 4, 8 %) ferroelectric ceramics irradiated by a high-current pulsed electron beam, the oscillating charge and first evidence for neutrinoless double beta decay
International Nuclear Information System (INIS)
Bohr, A.
1976-01-01
Nuclear structure theories are reviewed concerned with nuclei rotational motion. The development of the deformed nucleus model facilitated a discovery of rotational spectra of nuclei. Comprehensive verification of the rotational scheme and a successful classification of corresponding spectra stimulated investigations of the rotational movement dynamics. Values of nuclear moments of inertia proved to fall between two marginal values corresponding to rotation of a solid and hydrodynamic pattern of an unrotating flow, respectively. The discovery of governing role of the deformation and a degree of a symmetry violence for determining rotational degrees of freedon is pointed out to pave the way for generalization of the rotational spectra
Study of high-spin structure of the nuclei around A∼120 near proton-drip line
International Nuclear Information System (INIS)
Ray, I; Datta Pramanik, U.; Banerjee, P.; Bhattacharya, S.; Goswami, A.; Kshetri, R.; Mukherjee, A.; Mukherjee, B.; Saha Sarkar, M.; Basu, S.K.; Bhowmik, R.K.; Rakesh Kumar; Muralithar, S.; Singh, R.P.; Mandal, S.; Ranjet
2005-01-01
It would be interesting to explore the shell structure for nuclei near proton-drip line. The nuclei around A∼ 110-130 region show a wide range of interesting features in high spin states which reflect different types of symmetry breaking mechanisms as well as maintaining symmetries
Fusion excitation functions involving transitional nuclei
Energy Technology Data Exchange (ETDEWEB)
Rehm, K.E.; Jiang, C.L.; Esbensen, H. [and others
1995-08-01
Measurements of fusion excitation functions involving transitional nuclei {sup 78}Kr and {sup 100}Mo showed a different behavior at low energies, if compared to measurements with {sup 86}Kr and {sup 92}Mo. This points to a possible influence of nuclear structure on the fusion process. One way to characterize the structure of vibrational nuclei is via their restoring force parameters C{sub 2} which can be calculated from the energy of the lowest 2{sup +} state and the corresponding B(E2) value. A survey of the even-even nuclei between A = 28-150 shows strong variations in C{sub 2} values spanning two orders of magnitude. The lowest values for C{sub 2} are observed for {sup 78}Kr, {sup 104}Ru and {sup 124}Xe followed by {sup 74,76}Ge, {sup 74,76}Se, {sup 100}Mo and {sup 110}Pd. In order to learn more about the influence of {open_quotes}softness{close_quotes} on the sub-barrier fusion enhancement, we measured cross sections for evaporation residue production for the systems {sup 78}Kr + {sup 104}Ru and {sup 78}Kr + {sup 76}Ge with the gas-filled magnet technique. For both systems, fusion excitation functions involving the closed neutron shell nucleus {sup 86}Kr were measured previously. The data are presently being analyzed.
Shell closure in stable and unstable Fermion systems
International Nuclear Information System (INIS)
Lombard, R.J.
1991-01-01
Some of the findings of calculations performed with the density functional method in connection with shell closure are presented. In nuclei, some evidences seam to confirm the existence of a shell closure at N or Z=16, for Z or N<11. More data, particularly spectroscopic measurements would provide further information. Single particle energies for Z=16 isotopes as function of the neutron number N are given. (G.P.) 9 refs.; 6 figs
Nuclear shell effect and collinear tripartition of nuclei
Indian Academy of Sciences (India)
2015-08-04
Aug 4, 2015 ... 1Joint Institute for Nuclear Research, 141980 Dubna, Moscow Region, Russia ... Recent experimental observations of the two fragment yields in ... to be one of the mechanisms of true ternary fission, when the masses of its ...
Decay of Hot Nuclei at Low Spins Produced by Antiproton-Annihilation in Heavy Nuclei
2002-01-01
% PS208 \\\\ \\\\ The objective of the experiment is to study (i) the thermal excitation energy distribution of antiproton-induced reactions in heavy nuclei and (ii) the decay properties of hot nuclei at low spins via evaporation, multifragmentation and fission as a function of excitation energy. The experimental set-up consists of 4-$\\pi$ detectors: the Berlin Neutron Ball~(BNB) which is a spherical shell of gadolinium-loaded scintillator liquid with an inner and outer diameter of 40 and 160~cm, respectively. This detector counts the number of evaporated neutrons in each reaction. Inside BNB there is a 4-$\\pi$ silicon ball~(BSIB) with a diameter of 20~cm consisting of 162 detectors which measure energy and multiplicity of all emitted charged nuclear particles. The particles are identified via time of flight, energy and pulse shape correlations.
Particle-hole excitations in N=50 nuclei
International Nuclear Information System (INIS)
Johnstone, I.P.; Skouras, L.D.
1997-01-01
Energy levels in N=50 nuclei are calculated allowing single-particle excitations from the p 1/2 and g 9/2 shells into the d 5/2 , s 1/2 , d 3/2 , and g 7/2 shells. Important parts of the interaction are determined by least-squares fits to known levels. Agreement with experiment is very good. The high-spin particle-hole states appear to be mainly yrast levels in mass 93 and higher, but are not in 90 Zr. copyright 1997 The American Physical Society
File Specification for GEOS-5 FP (Forward Processing)
Lucchesi, R.
2013-01-01
The GEOS-5 FP Atmospheric Data Assimilation System (GEOS-5 ADAS) uses an analysis developed jointly with NOAA's National Centers for Environmental Prediction (NCEP), which allows the Global Modeling and Assimilation Office (GMAO) to take advantage of the developments at NCEP and the Joint Center for Satellite Data Assimilation (JCSDA). The GEOS-5 AGCM uses the finite-volume dynamics (Lin, 2004) integrated with various physics packages (e.g, Bacmeister et al., 2006), under the Earth System Modeling Framework (ESMF) including the Catchment Land Surface Model (CLSM) (e.g., Koster et al., 2000). The GSI analysis is a three-dimensional variational (3DVar) analysis applied in grid-point space to facilitate the implementation of anisotropic, inhomogeneous covariances (e.g., Wu et al., 2002; Derber et al., 2003). The GSI implementation for GEOS-5 FP incorporates a set of recursive filters that produce approximately Gaussian smoothing kernels and isotropic correlation functions. The GEOS-5 ADAS is documented in Rienecker et al. (2008). More recent updates to the model are presented in Molod et al. (2011). The GEOS-5 system actively assimilates roughly 2 × 10(exp 6) observations for each analysis, including about 7.5 × 10(exp 5) AIRS radiance data. The input stream is roughly twice this volume, but because of the large volume, the data are thinned commensurate with the analysis grid to reduce the computational burden. Data are also rejected from the analysis through quality control procedures designed to detect, for example, the presence of cloud. To minimize the spurious periodic perturbations of the analysis, GEOS-5 FP uses the Incremental Analysis Update (IAU) technique developed by Bloom et al. (1996). More details of this procedure are given in Appendix A. The assimilation is performed at a horizontal resolution of 0.3125-degree longitude by 0.25- degree latitude and at 72 levels, extending to 0.01 hPa. All products are generated at the native resolution of the
Study of band structure in 78,80Sr using Triaxial Projected Shell Model
International Nuclear Information System (INIS)
Behera, N.; Naik, Z.; Bhat, G.H.; Sheikh, J.A.; Palit, R.; Sun, Y.
2017-01-01
The purpose of present work is to carry out a systematic study of the yrast-band and gamma-band structure for the even-even 78-80 Sr nuclei using Triaxial Projected Shell Model (TPSM) approach. These nuclei were chosen because 78 Sr has well developed side band(unassigned configuration) and 80 Sr has well developed band observed experimentally
International Nuclear Information System (INIS)
Henley, E.M.
1987-01-01
Nuclei are very useful for testing symmetries, and for studies of symmetry breaking. This thesis is illustrated for two improper space-time transformations, parity and time-reversal and for one internal symmetry: charge symmetry and independence. Recent progress and present interest is reviewed. 23 refs., 8 figs., 2 tabs
Electroweak interactions in nuclei
International Nuclear Information System (INIS)
Henley, E.M.
1984-06-01
Topics include: introduction to electroweak theory; the Weinberg-Salam theory for leptons; the Weinberg-Salam theory for hadrons-the GIM mechanism; electron scattering as a probe of the electroweak interaction (observation of PV, the weak interaction for nucleons, and parity violation in atoms); and time reversed invariance and electric dipole moments of nucleons, nuclei, and atoms. 52 references
Transfer involving deformed nuclei
International Nuclear Information System (INIS)
Rasmussen, J.O.; Guidry, M.W.; Canto, L.F.
1985-03-01
Results are reviewed of 1- and 2-neutron transfer reactions at near-barrier energies for deformed nuclei. Rotational angular momentum and excitation patterns are examined. A strong tendency to populating high spin states within a few MeV of the yrast line is noted, and it is interpreted as preferential transfer to rotation-aligned states. 16 refs., 12 figs
International Nuclear Information System (INIS)
Gulamov, K.G.
1987-01-01
It is well known that interactions of high energy particles with nuclei, owing to possible intranuclear rescatterings, may provide information about the space-time behaviour of the production process. Therefore the main goals of these investigations are related with the attempts to study the space-time process of hadronization of coloured quarks and gluons produced at the initial stage of an interaction to white final state particles and to clarify the influence of composite quark-gluon structure of both the projectile and target on features of the production mechanisms. Since in both the initial and final states of these reactions the authors have strongly interacting multiparticle systems, it is of importance to study the collective properties of these systems. The questions to the point are: what is the degree of collectivization of particles newly produced in collisions with nuclei and what is the influence of the collective nature of a nucleus itself on the production mechanisms, in particular, what are the manifestations of possible multinucleon (multiquark) configurations in nuclei? It is obvious that the reductability of, say, hadron-nucleus (hA) interaction to hadron-nucleon (hN) collisions is directly related to the above problems. Due to time limitations the author discusses here only a few aspects of low p/sub t/ hA interactions which in his opinion are of importance for better understanding of general regularities of collisions with nuclei and for further investigations of the above problems
International Nuclear Information System (INIS)
Laget, J.M.
1988-01-01
This summary is a review of our understanding of nuclei in terms of hadrons exchanging mesons. The open problems are: the determination of the high momentum components of nuclear systems, the role of the three-body forces and the nature of the short range correlations. The ways of studying these problems are discussed
Electromagnetic structure of nuclei
International Nuclear Information System (INIS)
Arnold, R.G.
1986-07-01
A brief review is given of selected topics in the electromagnetic structure of nucleons and nuclei, including nucleon form factors from both quantum chromodynamics and electron scattering data, measurements of the deuteron and triton form factors, quasi-elastic scattering, and the EMC effect. 47 refs., 13 figs
International Nuclear Information System (INIS)
Bohr, A.
1977-01-01
History is surveyed of the development of the theory of rotational states in nuclei. The situation in the 40's when ideas formed of the collective states of a nucleus is evoked. The general rotation theory and the relation between the single-particle and rotational motion are briefly discussed. Future prospects of the rotation theory development are indicated. (I.W.)
International Nuclear Information System (INIS)
Truhlik, E.; Mach, R.
1992-01-01
62 papers and one summary talk were presented at the conference, on subject matters in between nuclear physics (mainly light nuclei) and elementary particle physics, as indicated by the session headings (1) Electroweak nuclear interaction (2) Nuclear physics with pions and antiprotons (3) Nuclear physics with strange particles (4) Relativistic nuclear physics (5) Quark degrees of freedom. (Quittner)
International Nuclear Information System (INIS)
Mittig, W.; Plagnol, E.; Schutz, Y.
1989-11-01
A new simple direct method for the measurement of the total reaction cross section (σ R ) for several light radioactive nuclei (A≤40) is developed. From that, the reduced strong absorption radii (r o 2 ) are obtained. A comparison is made with data obtained by other techniques. A strong isospin dependence of the nuclear radii is observed. (L.C.) [pt
International Nuclear Information System (INIS)
Hodgson, P.E.
1990-01-01
The effects of nucleon clustering in nuclei are described, with reference to both nuclear structure and nuclear reactions, and the advantages of using the cluster formalism to describe a range of phenomena are discussed. It is shown that bound and scattering alpha-particle states can be described in a unified way using an energy-dependent alpha-nucleus potential. (author)
International Nuclear Information System (INIS)
Harris, J.
1986-01-01
The book on particles, imaging and nuclei is one of the Background Readers for the Revised Nuffield Advanced Physics course. The contents contain five educational articles, which extend concepts covered in the course and examine recent developments in physics. Four of the articles on:- particles and the forces of nature, radioisotopes, lasers probe the atomic nucleus, and nuclear history, are indexed separately. (UK)
International Nuclear Information System (INIS)
Moretto, L.G.; Wozniak, G.J.
1988-11-01
The formation of hot compound nuclei in intermediate-energy heavy ion reactions is discussed. The statistical decay of such compound nuclei is responsible for the abundant emission of complex fragments and high energy gamma rays. 43 refs., 23 figs
Isotope shifts in unstable nuclei
International Nuclear Information System (INIS)
Rebel, H.
1980-05-01
Current experimental investigations of isotope shifts in atomic spectra of unstable nuclei and the resulting information about size and shape of nuclei far off stability are discussed with reference to some representative examples. (orig.)
International Nuclear Information System (INIS)
Van Isacker, P
2011-01-01
Seniority isomers are nuclear states with an electromagnetic decay that is hindered by selection rules related to the seniority quantum number. A simple analysis is presented of their possible formation with reference to the nickel isotopes 70–76 Ni and the N = 50 isotones from molybdenum to cadmium. It is shown that the existence of seniority isomers in a j = 9/2 shell is predominantly governed by the quadrupole pairing matrix element of the nucleon-nucleon interaction. The analysis is generalized to shells with larger j.
International Nuclear Information System (INIS)
Harvey, M.; Khanna, F.C.
1975-01-01
The general problem of what constitutes a physical model and what is known about the free nucleon-nucleon interaction are considered. A time independent formulation of the basic equations is chosen. Construction of the average field in which particles move in a general independent particle model is developed, concentrating on problems of defining the average spherical single particle field for any given nucleus, and methods for construction of effective residual interactions and other physical operators. Deformed shell models and both spherical and deformed harmonic oscillator models are discussed in detail, and connections between spherical and deformed shell models are analyzed. A section on cluster models is included. 11 tables, 21 figures
Core polarization and the Coulomb energy difference of mirror nuclei
International Nuclear Information System (INIS)
Barroso, A.
1977-01-01
The effect of the core polarization on the Coulomb displacement energies of mirror nuclei with a LS doubly closed shell plus or minus one nucleon is studied. Using the Kallio-Kolltveit interaction it is found that the first-order configuration mixing including 2p-2h core excitations is too small and sometimes of the wrong sign to explain the Nolen-Schiffer anomaly. (Auth.)
Classically dynamical behaviour of single particle in heavy nuclei
International Nuclear Information System (INIS)
Gu Jianzhong; Zhuo Yizhong; Wu Xizhen
1998-01-01
A detailed analysis of the classically dynamical behaviour of a nucleon in heavy nuclei in terms of the TCSM (two-center shell model) is presented. Poincare section is a convenient and reliable criterion to judge the regularity (or chaoticity) of a classical system. The numerical calculations in this work are carried out for a nucleon in 238 U. The Poincare section map and the Poincare surface of section for different conditions are presented
Isospin dependence of the spin-orbit splitting in nuclei
International Nuclear Information System (INIS)
Isakov, V.I.
2007-01-01
The analysis has been made of experimental data on level spectra, single-nucleon transfer reactions near closed shells, and data on polarization effects in charge-exchange (p, n) reactions between isoanalogous states of nuclei with even A. It is concluded that there is a significant difference between the spin-orbit splittings of neutrons and protons in identical orbitals. This conclusion is confirmed in the frame work of different theoretical approaches [ru
Magicity of neutron-rich nuclei within relativistic self-consistent approaches
Directory of Open Access Journals (Sweden)
Jia Jie Li
2016-02-01
Full Text Available The formation of new shell gaps in intermediate mass neutron-rich nuclei is investigated within the relativistic Hartree–Fock–Bogoliubov theory, and the role of the Lorentz pseudo-vector and tensor interactions is analyzed. Based on the Foldy–Wouthuysen transformation, we discuss in detail the role played by the different terms of the Lorentz pseudo-vector and tensor interactions in the appearing of the N=16, 32 and 34 shell gaps. The nuclei 24O, 48Si and 52,54Ca are predicted with a large shell gap and zero (24O, 52Ca or almost zero (48Si, 54Ca pairing gap, making them candidates for new magic numbers in exotic nuclei. We find from our analysis that the Lorentz pseudo-vector and tensor interactions induce very specific evolutions of single-particle energies, which could clearly sign their presence and reveal the need for relativistic approaches with exchange interactions.
High spin spectroscopy of near spherical nuclei: Role of intruder orbitals
Energy Technology Data Exchange (ETDEWEB)
Bhattacharyya, S.; Bhattacharjee, T.; Mukherjee, G. [Variable Energy Cyclotron Centre, 1/AF Bidhan Nagar, Kolkata - 700064 (India); Chanda, S. [Fakir Chand College, Diamond Herbour, West Bengal (India); Banerjee, D.; Das, S. K.; Guin, R. [Radiochemistry Division, Variable Energy Cyclotron Centre, BARC, Kolkata - 700064 (India); Gupta, S. Das [Variable Energy Cyclotron Centre, 1/AF Bidhan Nagar, Kolkata - 700064, India and Saha Institute of Nuclear Physics, Kolkata-700064 (India); Pai, H. [Variable Energy Cyclotron Centre, 1/AF Bidhan Nagar, Kolkata - 700064, India and Institut für Kernphysik, Technische Universität Darmstadt, Schlossgartenstrasse 9, 64289 Darmstadt (Germany)
2014-08-14
High spin states of nuclei in the vicinity of neutron shell closure N = 82 and proton shell closure Z = 82 have been studied using the Clovere Ge detectors of Indian National Gamma Array. The shape driving effects of proton and neutron unique parity intruder orbitals for the structure of nuclei around the above shell closures have been investigated using light and heavy ion beams. Lifetime measurements of excited states in {sup 139}Pr have been done using pulsed-beam-γ coincidence technique. The prompt spectroscopy of {sup 207}Rn has been extended beyond the 181μs 13/2{sup +} isomer. Neutron-rich nuclei around {sup 132}Sn have been produced from proton induced fission of {sup 235}U and lifetime measurement of low-lying states of odd-odd {sup 132}I have been performed from offline decay.
Gross theory of beta-decay and half-lives of short-lived nuclei
International Nuclear Information System (INIS)
Yamada, Masami; Kondo, Norikatsu.
1976-01-01
The gross theory of beta-decay has been developed, and this theory offers the means of calculating directly the function of beta-decay intensity, then half-lives, complex beta spectra and so on are estimated from it. This paper presents the more refined theory by introducing the shell effect. The shell effect is considered in the intensity function. The half-lives in the electron decay of In with spin of 9/2 + , the positron decay of Bi, Po, At and Rn, and the decay of odd-odd nuclei were estimated. The introduction of the shell effect shows better agreement between the theory and the experimental data. The inequality relations of intensity functions and half-lives of two adjacent nuclei were obtained. When the spins and parities of two nuclei are same, the inequality relations hold especially good. (Kato, T.)
Energetic Nuclei, Superdensity and Biomedicine
Baldin, A. M.
1977-01-01
High-energy, relativistic nuclei were first observed in cosmic rays. Studing these nuclei has provided an opportunity for analyzing the composition of cosmic rays and for experimentally verifying principles governing the behavior of nuclear matter at high and super-high temperatures. Medical research using accelerated nuclei is suggested.…
1981-01-01
for the ~AUG18IS~ 1W Symposium on Comites and Advanced Materials*M sponsored by the American Ceramic Society Coco Beach, Florida, January 18424, 1981E...properties of cFP-A203 fiber reinforced composites prepared by liquid metal infiltration f a techniques. The first approach was the incorporation of a...coated FP-A1203 fibers in the composites. This coating is readily wet by molten aluminum and permitted the use of more conventional aluminum alloys
High spin rotations of nuclei with the harmonic oscillator potential
International Nuclear Information System (INIS)
Cerkaski, M.; Szymanski, Z.
1978-01-01
Calculations of the nuclear properties at high angular momentum have been performed recently. They are based on the liquid drop model of a nucleus and/or on the assumption of the single particle shell structure of the nucleonic motion. The calculations are usually complicated and involve long computer codes. In this article we shall discuss general trends in fast rotating nuclei in the approximation of the harmonic oscillator potential. We shall see that using the Bohr Mottelson simplified version of the rigorous solution of Valatin one can perform a rather simple analysis of the rotational bands, structure of the yrast line, moments of inertia etc. in the rotating nucleus. While the precision fit to experimental data in actual nuclei is not the purpose of this paper, one can still hope to reach some general understanding within the model of the simple relations resulting in nuclei at high spin. (author)
Disintegration of comet nuclei
International Nuclear Information System (INIS)
Ksanfomality, Leonid V
2012-01-01
The breaking up of comets into separate pieces, each with its own tail, was seen many times by astronomers of the past. The phenomenon was in sharp contrast to the idea of the eternal and unchangeable celestial firmament and was commonly believed to be an omen of impending disaster, especially for comets with tails stretching across half the sky. It is only now that we have efficient enough space exploration tools to see comet nuclei and even - in the particular case of small comet Hartley-2 in 2010 - to watch their disintegration stage. There are also other suspected candidates for disintegration in the vast family of comet nuclei and other Solar System bodies. (physics of our days)
International Nuclear Information System (INIS)
Huefner, J.
1975-01-01
Are pions a good tool to study nuclei. If the emphasis of this question rests on ''tool'', the answer must be ''not yet.'' The reason: one does not even understand how a pion interacts with a nucleus. This is part of the many-body problem for strongly interacting particles and its study is a basic problem in physics. One must investigate questions like: Can one understand pion-nucleus interactions from pion-nucleon physics. How does a Δ-resonance look in nuclei. Once one has solved those basic problems, there will be spinoffs in medical, technical and nuclear areas. Then pions can be used as a tool to study nuclear properties
International Nuclear Information System (INIS)
Whelan, N.D.
1993-01-01
Random Matrix Theory successfully describes the statistics of the low-lying spectra of some nuclei but not of others. It is currently believed that this theory applies to systems in which the corresponding classical motion is chaotic. This conjecture is tested for collective nuclei by studying the Interacting Boson Model. Quantum and classical measures of chaos are proposed and found to be in agreement throughout the parameter space of the model. For some parameter values the measures indicate the presence of a previously unknown approximate symmetry. A phenomenon called partial dynamical symmetry is explored and shown to lead to a suppression of chaos. A time dependent function calculated from the quantum spectrum is discussed. This function is sensitive to the extent of chaos and provides a robust method of analyzing experimental spectra
A study on the spiral shell in Dianchi, Yunnan, as domestic feed
International Nuclear Information System (INIS)
Ma Shouxiang; Yang Ruikun
1990-01-01
This article studies the accumulation and the metastasis of natural radioactive nuclei in the corporal of chicken when spiral shell is used as domestic feed. The result shows that the contents of natural radioactivity nuclei U, Th, and 226 Ra vary with the chicken meat, chicken bone, chicken egg and egg capsule. Their accumulation and metastasis are in the order: Th > U > 226 Ra, but the levels of the three radioactive nuclei are all below the limited levels of radioactive substances in the food standard of the People's Republic of China. This study provides a basis for developing and making use of the spiral shell as domestic feed in Dianchi, Yunnan
International Nuclear Information System (INIS)
Mitchel, G.; Shriner, J.
2005-01-01
Although the predictions of Random Matrix Theory (RMT) were available by the early 1960s, data of sufficiently high quality to adequately test the theory were only obtained a decade later by Rainwater. It was another decade later that Bohigas, Haq and Pandey combined the best available nuclear resonance data - the Columbia neutron resonances in heavy nuclei and the TUNL proton resonances in lighter nuclei - to form the Nuclear Data Ensemble. They obtained excellent agreement for the level statistics with the RMT predictions. The expected Porter-Thomas (PT) distribution was considered very early. However, since the widths (amplitudes squared) are measured, the predicted Gaussian distribution for the amplitudes was only qualitatively confirmed. A much more sensitive test was performed by measuring two widths and the relative phase between the two amplitudes. By comparison of the width and amplitude correlations, the Gaussian distribution was confirmed at the 1% level. Following the Bohigas conjecture - that quantum analogs of classically chaotic systems obey RMT - there was an explosion of activity utilizing level statistics in many different quantum systems. In nuclei the focus was verifying the range of applicability of RMT. Of particular interest was the effect of collectivity and of excitation energy on statistical properties. The effect of symmetry breaking on level statistics was examined and early predictions by Dyson were confirmed. The effect of symmetry breaking on the width distribution was also measured for the first time. Although heuristic arguments predicted no change from the PT distribution, experimentally there was a large deviation from the PT prediction. Later theoretical efforts were consistent with this result. The stringent conditions placed on the experiments - for eigenvalue tests the data need to be essentially perfect (few or no missing levels or mis assigned quantum numbers) - has limited the amount of suitable experimental data. The
Study on rotational bands in odd-odd nuclei 102,l04Nb by using PSM
International Nuclear Information System (INIS)
Dong Yongsheng; Hu Wentao; Feng Youliang; Wang Jinbao; Yu Shaoying; Shen Caiwan
2012-01-01
The Projected Shell Model (PSM) is used to study the low energy scheme of the neutron-rich normal-deformed isotopes of odd-odd nuclei 102,104 Nb. The quasiparticle configuration is assigned. The theoretical calculations of the energy band of 102,104 Nb could well reproduce the experimental data. It is shown that PSM is a valid method for studying the low energy scheme of heavy nuclei. (authors)
Multiphonon states in even-even spherical nuclei. Pt.1. Calculation of the overlap matrix
International Nuclear Information System (INIS)
Piepenbring, R.; Protasov, K.V.; Silvestre-Brac, B.
1995-01-01
The multiphonon method, previously developed for deformed nuclei is extended to the case of even-even spherical nuclei. Recursion formulae, well suited for numerical calculations are given for the overlap matrix elements. The method is illustrated for a single j-shell, where S-, D-, G-, .. phonons are introduced. In such an approach, the Pauli principle is fully and properly taken into account. ((orig.))
The broken-pair model for nuclei and its extension with quadrupole vibrations
International Nuclear Information System (INIS)
Hofstra, P.
1979-01-01
The author presents calculations for low energy properties of nuclei with an odd number of particles. These are described in the Broken-Pair approximation, where it is assumed that all but three particles occur as ordered Cooper pairs; the unpaired (one or three) particles are called quasiparticles. A model is developed with which it is hoped to describe odd nuclei with two open shells in terms of both single-particle and collective degrees of freedom. (Auth.)
Equilibrium deformations of single-particle states of odd nuclei of rare earth region
International Nuclear Information System (INIS)
Alikov, B.A.; Tsoj, E.G.; Zuber, K.; Pashkevich, V.V.
1983-01-01
In terms of the Strutinsky shell-correction method using the Woods-Saxon non-spherical potential the energies, quadrupole, and hexadecapole momenta of the ground and excited states of odd-proton nuclei with 61 6 deformation on atomic nuclei non-rotation states energies is discussed. It is shown that account of deformation of α 6 type slightly influences on the quadrupole and hexadecapole deformation value
Elusive active galactic nuclei
Maiolino, R.; Comastri, A.; Gilli, R.; Nagar, N. M.; Bianchi, S.; Böker, T.; Colbert, E.; Krabbe, A.; Marconi, A.; Matt, G.; Salvati, M.
2003-10-01
A fraction of active galactic nuclei do not show the classical Seyfert-type signatures in their optical spectra, i.e. they are optically `elusive'. X-ray observations are an optimal tool to identify this class of objects. We combine new Chandra observations with archival X-ray data in order to obtain a first estimate of the fraction of elusive active galactic nuclei (AGN) in local galaxies and to constrain their nature. Our results suggest that elusive AGN have a local density comparable to or even higher than optically classified Seyfert nuclei. Most elusive AGN are heavily absorbed in the X-rays, with gas column densities exceeding 1024 cm-2, suggesting that their peculiar nature is associated with obscuration. It is likely that in elusive AGN the nuclear UV source is completely embedded and the ionizing photons cannot escape, which prevents the formation of a classical narrow-line region. Elusive AGN may contribute significantly to the 30-keV bump of the X-ray background.
Symmetry-guided large-scale shell-model theory
Czech Academy of Sciences Publication Activity Database
Launey, K. D.; Dytrych, Tomáš; Draayer, J. P.
2016-01-01
Roč. 89, JUL (2016), s. 101-136 ISSN 0146-6410 R&D Projects: GA ČR GA16-16772S Institutional support: RVO:61389005 Keywords : Ab intio shell -model theory * Symplectic symmetry * Collectivity * Clusters * Hoyle state * Orderly patterns in nuclei from first principles Subject RIV: BE - Theoretical Physics Impact factor: 11.229, year: 2016
New high spin states and isomers in the {sup 208}Pb and {sup 207}Pb nuclei
Energy Technology Data Exchange (ETDEWEB)
Broda, R.; Wrzesinski, J.; Pawlat, T. [and others
1996-12-31
The two most prominent examples of the heavy doubly closed shell (DCS) nuclei, {sup 208}Pb and {sup 132}Sn, are not accessible by conventional heavy-ion fusion processes populating high-spin states. This experimental difficulty obscured for a long time the investigation of yrast high-spin states in both DCS and neighboring nuclei and consequently restricted the study of the shell model in its most attractive regions. Recent technical development of multidetector gamma arrays opened new ways to exploit more complex nuclear processes which populate the nuclei of interest with suitable yields for gamma spectroscopy and involve population of moderately high spin states. This new possibility extended the range of accessible spin values and is a promising way to reach new yrast states. Some of these states are expected to be of high configurational purity and can be a source of important shell model parameters which possibly can be used later to check the validity of the spherical shell model description at yet higher spin and higher excitation energy. The nuclei in the closest vicinity of {sup 132}Sn are produced in spontaneous fission and states with spin values up to I=14 can be reached in fission gamma spectroscopy studies with the presently achieved sensitivity of gamma arrays. New results on yrast states in the {sup 134}Te and {sup 135}I nuclei populated in fission of the {sup 248}Cm presented at this conference illustrate such application of the resolving power offered by modern gamma techniques.
Study of subshell gap around N = 70 for neutron-rich nuclei
International Nuclear Information System (INIS)
Hemalatha, M.
2011-01-01
The study and search for new regions of shell closure for nuclei away from stability is a topic of current interest both experimentally and theoretically. There have been few studies predicting a weak spherical subshell gap of 110 Zr (N = 70), for example. This is supported by a recent study indicating that the spherical N = 70 shell gap may not have a large effect at N = 68 for Zr isotopes. It would be, therefore, interesting to know whether there is a subshell closure at N = 70 in the neutron rich region and also for the very neutron-rich nuclei, 110 Zr
Phebus FP: organisation of the project and international collaboration
International Nuclear Information System (INIS)
Tattegrain, A.; Hardt, P. von der
1992-01-01
PHEBUS Fission Product (FP) Research Programme developed from the initial French design study into a European project, and further into an international programme by agreements with overseas partners during the past two years. The programme is supervised by a Steering Committee which reviews the technical-scientific options and the results. The executive body under the Committee, the Project Group, includes a Commissariat a l'Energie Atomique (CEA) and Commission of the European Communities (CEC) manager as well as three (CEA) project leaders for design and manufacture, experiment operation, and interpretation of test results. The Steering Committee can request expertise from the two working groups the Analytical Group (SAWG) (elaborating test objectives, carrying out reactor calculations and test precalculations) and the Technical Group (TG) (assessing the designs proposed and the results obtained by the Project Group). A third group looks into financial aspects of the CEA-CEC contract only. The two working groups, SAWG and TG, play an important role in the exchange of information and of expertise between all partners. The paper reviews the internal Project organisation and the collaboration network, inside the European Community and through CEA overseas. (author)
Spectroscopy of light nuclei with realistic NN interaction JISP
International Nuclear Information System (INIS)
Shirokov, A. M.; Vary, J. P.; Mazur, A. I.; Weber, T. A.
2008-01-01
Recent results of our systematic ab initio studies of the spectroscopy of s- and p-shell nuclei in fully microscopic large-scale (up to a few hundred million basis functions) no-core shell-model calculations are presented. A new high-quality realistic nonlocal NN interaction JISP is used. This interaction is obtained in the J-matrix inverse-scattering approach (JISP stands for the J-matrix inverse-scattering potential) and is of the form of a small-rank matrix in the oscillator basis in each of the NN partial waves, providing a very fast convergence in shell-model studies. The current purely two-body JISP model of the nucleon-nucleon interaction JISP16 provides not only an excellent description of two-nucleon data (deuteron properties and np scattering) with χ 2 /datum = 1.05 but also a better description of a wide range of observables (binding energies, spectra, rms radii, quadrupole moments, electromagnetic-transition probabilities, etc.) in all s-and p-shell nuclei than the best modern interaction models combining realistic nucleon-nucleon and three-nucleon interactions.
Structure of the N=50 As, Ge, Ga nuclei
International Nuclear Information System (INIS)
Sahin, E.; Angelis, G. de; Duchene, G.; Faul, T.; Gadea, A.; Lisetskiy, A.F.; Ackermann, D.; Algora, A.; Aydin, S.; Azaiez, F.; Bazzacco, D.; Benzoni, G.; Bostan, M.; Byrski, T.; Celikovic, I.; Chapman, R.; Corradi, L.
2012-01-01
The level structures of the N=50 83 As, 82 Ge, and 81 Ga isotones have been investigated by means of multi-nucleon transfer reactions. A first experiment was performed with the CLARA-PRISMA setup to identify these nuclei. A second experiment was carried out with the GASP array in order to deduce the γ-ray coincidence information. The results obtained on the high-spin states of such nuclei are used to test the stability of the N=50 shell closure in the region of 78 Ni (Z=28). The comparison of the experimental level schemes with the shell-model calculations yields an N=50 energy gap value of 4.7(3) MeV at Z=28. This value, in a good agreement with the prediction of the finite-range liquid-drop model as well as with the recent large-scale shell model calculations, does not support a weakening of the N=50 shell gap down to Z=28.
Distribution of a vacuum charge near supercharged nuclei
International Nuclear Information System (INIS)
Migdal, A.B.; Popov, V.S.; Voskresenskij, D.N.; Gosudarstvennyj Komitet po Ispol'zovaniyu Atomnoj Ehnergii SSSR, Moscow. Inst. Teoreticheskoj i Ehksperimental'noj Fiziki)
1977-01-01
The distribution of a vacuum charge near super-critical nuclei (Ze 2 > > 1) is found. The calculation is performed in the Thomas - Fermi approximation extended to the relativistic case. The characteristic parameter in the present problem is Ze 3 approximately Z/1600. For Ze 3 approximately 1 the total charge of the vacuum shell becomes comparable to the nuclear charge Z. The relativistic Thomas - Fermi equation for the vacuum shell of a supercritical atom is solved analytically for two extreme cases, Ze 3 3 > > 1. In the intermediate region, Ze 3 approximately 1, the equation is solved numerically. The Thomas - Fermi equation for a neutral atom (in which not only the vacuum but external electron shells as well are filled up) and also the equation in which allowance is made for exchange and correlation corrections (relativistic generalization of the Thomas -Fermi - Dirac equation) are also considered
osFP: a web server for predicting the oligomeric states of fluorescent proteins.
Simeon, Saw; Shoombuatong, Watshara; Anuwongcharoen, Nuttapat; Preeyanon, Likit; Prachayasittikul, Virapong; Wikberg, Jarl E S; Nantasenamat, Chanin
2016-01-01
Currently, monomeric fluorescent proteins (FP) are ideal markers for protein tagging. The prediction of oligomeric states is helpful for enhancing live biomedical imaging. Computational prediction of FP oligomeric states can accelerate the effort of protein engineering efforts of creating monomeric FPs. To the best of our knowledge, this study represents the first computational model for predicting and analyzing FP oligomerization directly from the amino acid sequence. After data curation, an exhaustive data set consisting of 397 non-redundant FP oligomeric states was compiled from the literature. Results from benchmarking of the protein descriptors revealed that the model built with amino acid composition descriptors was the top performing model with accuracy, sensitivity and specificity in excess of 80% and MCC greater than 0.6 for all three data subsets (e.g. training, tenfold cross-validation and external sets). The model provided insights on the important residues governing the oligomerization of FP. To maximize the benefit of the generated predictive model, it was implemented as a web server under the R programming environment. osFP affords a user-friendly interface that can be used to predict the oligomeric state of FP using the protein sequence. The advantage of osFP is that it is platform-independent meaning that it can be accessed via a web browser on any operating system and device. osFP is freely accessible at http://codes.bio/osfp/ while the source code and data set is provided on GitHub at https://github.com/chaninn/osFP/.Graphical Abstract.
Fourth nuclear theory workshop 'clusters in nuclei'
Energy Technology Data Exchange (ETDEWEB)
NONE
2005-07-01
This document gathers the slides of 3 lectures: 1) the R-matrix method, 2) from realistic NN-interactions to cluster structures in nuclei - in this part the unitary correlation operator method (UCOM) is applied to 3 domains: the fermionic molecular dynamics, the Hartree-Fock approximation, and the no-core shell model -, and 3) the shell model point of view on cluster states.
EMC and polarized EMC effects in nuclei
Energy Technology Data Exchange (ETDEWEB)
Cloet, I.C. [Special Research Centre for the Subatomic Structure of Matter and Department of Physics and Mathematical Physics, University of Adelaide, SA 5005 (Australia); Jefferson Lab, 12000 Jefferson Avenue, Newport News, VA 23606 (United States)]. E-mail: icloet@jlab.org; Bentz, W. [Department of Physics, School of Science, Tokai University, Hiratsuka-shi, Kanagawa 259-1292 (Japan)]. E-mail: bentz@keyaki.cc.u-tokai.ac.jp; Thomas, A.W. [Jefferson Lab, 12000 Jefferson Avenue, Newport News, VA 23606 (United States)]. E-mail: awthomas@jlab.org
2006-11-09
We determine nuclear structure functions and quark distributions for {sup 7}Li, {sup 11}B, {sup 15}N and {sup 27}Al. For the nucleon bound state we solve the covariant quark-diquark equations in a confining Nambu-Jona-Lasinio model, which yields excellent results for the free nucleon structure functions. The nucleus is described using a relativistic shell model, including mean scalar and vector fields that couple to the quarks in the nucleon. The nuclear structure functions are then obtained as a convolution of the structure function of the bound nucleon with the light-cone nucleon distributions. We find that we are readily able to reproduce the EMC effect in finite nuclei and confirm earlier nuclear matter studies that found a large polarized EMC effect.
On single nucleon wave functions in nuclei
International Nuclear Information System (INIS)
Talmi, Igal
2011-01-01
The strong and singular interaction between nucleons, makes the nuclear many body theory very complicated. Still, nuclei exhibit simple and regular features which are simply described by the shell model. Wave functions of individual nucleons may be considered just as model wave functions which bear little resemblance to the real ones. There is, however, experimental evidence for the reality of single nucleon wave functions. There is a simple method of constructing such wave functions for valence nucleons. It is shown that this method can be improved by considering the polarization of the core by the valence nucleon. This gives rise to some rearrangement energy which affects the single valence nucleon energy within the nucleus.
Survey of intrinsic states of light nuclei
International Nuclear Information System (INIS)
Brink, D.M.
1975-01-01
The resonating group method and the generator coordinate method are two closely related theories of nuclear structure which can be used to construct wave functions describing cluster structures. In both cases the form of the intrinsic state implies a selection of those degrees of freedom which are regarded as being important for the problem under consideration. The form of the intrinsic state also corresponds to a particular truncation of the shell model space. In the resonating group method the effect of the Pauli principle leads to forbidden or redundant states of relative motion of clusters. An improved understanding of the role of forbidden states in the theory has led to important advances in the phenomenological description of cluster structures in nuclei. 3 tables, 2 figures
High and highest spin states in nuclei
International Nuclear Information System (INIS)
Ploszajczak, M.
1977-06-01
A study of the following phenomena in rotating nuclei is presented, namely: 1) the destruction of the pair-correlation between the protons and the neutrons as well as decoupling and orientation of the particles along the rotation axis; 2) the formation of a nucleus with axial symmetry rotating around the symmetry axis, caused by the strong centrifugal and Coriolis forces; 3) the shell effects at low angular momentum, which led in some Pb, Hg and Pt isotopes to the formation of a prolate nucleus, rotating around the symmetry axis; 4) the formation of longliving states at very high angular momenta ('Yrast-traps'). At low angular momenta the nucleus is described by the Cranking-Hartree-Fock-Bogolyubov theory (CHFB) with the pair-(P), quadrupole-(QQ) and hexade coupole force (HH) as residual interaction. (orig.) [de
Nuclei transmutation by collisions with fast hadrons and nuclei
International Nuclear Information System (INIS)
Strugalski, Z.; Strugalska-Gola, E.; Drzymala, A.
1998-01-01
Atomic nuclei change their mass- and charge-numbers if bombarded by fast hadrons and nuclei; the transmutation appears as a complicated process. It proceeds in a definite way - through a few stages or phases. Adequate identification of the nucleons and light nuclear fragments emitted and evaporated in a hadron-nucleus or nucleus-nucleus collisions and in the collision-induced intranuclear reactions allows one to estimate quantitatively the nuclei transmutations in the various stages (phases) of the process
Second proton and neutron alignments in the doubly-odd nuclei 154,156Tb
International Nuclear Information System (INIS)
Hartley, D.J.; Allen, J.L.; Brown, T.B.; Kondev, F.G.; Pfohl, J.; Riley, M.A.; Fischer, S.M.; Janssens, R.V.; Nisius, D.T.; Fallon, P.; Ma, W.C.; Simpson, J.
1999-01-01
High-spin states in the doubly-odd nuclei 154,156 Tb have been populated in two separate experiments using the 36 S+ 124 Sn reaction at different beam energies (160 and 175 MeV). The yrast structures of both nuclei were extended to much higher spin (I≤48ℎ) than previously known and several quasiparticle alignments have been identified. These include the second neutron alignment and a clear delineation of the second proton crossing in 156 Tb. Systematics of these crossings for odd-Z nuclei and comparisons with results of cranked shell model calculations are discussed. thinsp copyright 1999 The American Physical Society
Inner shell ionization accompanying nuclear collisions
International Nuclear Information System (INIS)
Sujkowski, Z.
1987-01-01
Selected phenomena leading to inner shell ionization and being of relevance for nuclear physics are discussed. The selection emphasizes the K-shell ionization induced in head-on collisions by fast light and medium-heavy ions. Cross-sections are reviewed. Effects of multiple inner shell ionization on the K X-ray spectra are illustrated with recent results. Implications for nuclear experiments are noted. Use of atomic observables as clocks for proton induced nuclear reactions is reviewed. Prospects for H.I. reactions are discussed. Preliminary experimental results on the direct K-shell ionization accompanying H.I. fusion reactions are presented. The post-collisional K-shell ionization due to internal conversion of γ-rays is discussed as the dominating contribution to the ionization for residues of dissipative nuclear reactions with Z > 40. Systematics of the corresponding K X-ray multiplicities are presented for rotational nuclei. These multiplicity values can be used for determining cross-sections for e.g. incomplete fusion reactions. Examples of such applications are given. Also discussed is the use of target K X-rays for normalization purposes and of the post-collisional, residue K X-rays in the studies of high spin phenomena. 96 references, 35 figures, 3 tables
International Nuclear Information System (INIS)
Ishiyama, Shintaro
2004-01-01
To estimate FP deposition rate on the typical turbomachinary, including gas turbine of GTHTR300 and exposure dose limit at its maintenance, FP plate-out analysis was been carried out using FP compound formation theory and FP concentration controlled diffusion mechanism. As the results, following conclusions were derived; (1) It is found that the analysis data computed by the VICTORIA code with assumption of the correct thickness of reactive zone exhibits very good correlation with the experimental data obtained by simulated FP plate-out experiment. (2) 137 Cs, 110m Ag and 137 Cs (131+133) I compound are major fission products deposited on the surface of turbomachinery. (3) Deposition rates of major FPs on the surface of gas turbine blade and disk are (131+133) I> 137 Cs> 110m Ag. (4) Total dose rate and allowable work time at turbine of GTHTR300 are given as 19.2 mSv/h and 2.6 h by VICTORIA code analysis and these values are conservative than that given by simple code analysis. (author)
International Nuclear Information System (INIS)
Gasparian, A.P.
1984-01-01
Results are presented from a bubble chamber experiment to search for anomalous mean free path (MFP) phenomena for secondary multicharged fragments (Zsub(f)=5 and 6) of the beam carbon nucleus at 4.2 GeV/c per nucleon. A total of 50000 primary interactions of carbon with propane (C 3 H 8 ) were created. Approximately 6000 beam tragments with charges Zsub(f)=5 and 6 were analyzed in detail to find out an anomalous decrease of MFP. The anomaly is observed only for secondary 12 C nuclei
International Nuclear Information System (INIS)
2001-01-01
The present collection of letters from JINR, Dubna, contains eight separate records on the interaction of high energy Λ 6 He hypernuclear beams with atomic nuclei, the position-sensitive detector of a high spatial resolution on the basis of a multiwire gas electron multiplier, pseudorapidity hadron density at the LHC energy, high precision laser control of the ATLAS tile-calorimeter module mass production at JINR, a new approach to ECG's features recognition involving neural network, subcriticity of a uranium target enriched in 235 U, beam space charge effects in high-current cyclotron injector CI-5, a homogeneous static gravitational field and the principle of equivalence
Beckmann, Volker
2012-01-01
This AGN textbook includes phenomena based on new results in the X-Ray domain from new telescopes such as Chandra and XMM Newton not mentioned in any other book. Furthermore, it considers also the Fermi Gamma Ray Space Telescope with its revolutionary advances of unprecedented sensitivity, field of view and all-sky monitoring. Those and other new developments as well as simulations of AGN merging events and formations, enabled through latest super-computing capabilities. The book gives an overview on the current knowledge of the Active Galacitc Nuclei phenomenon. The spectral energy d
Elementary excitations in nuclei
International Nuclear Information System (INIS)
Lemmer, R.H.
1987-01-01
The role of elementary quasi-particle and quasi-hole excitations is reviewed in connection with the analysis of data involving high-lying nuclear states. This article includes discussions on: (i) single quasi-hole excitations in pick-up reactions, (ii) the formation of single quasi-hole and quasi-particle excitations (in different nuclei) during transfer reactions, followed by (iii) quasi-particle quasi-hole excitations in the same nucleus that are produced by photon absorption. Finally, the question of photon absorption in the vicinity of the elementary Δ resonance is discussed, where nucleonic as well as nuclear degrees of freedom can be excited
International Nuclear Information System (INIS)
2000-01-01
The present collection of letters from JINR, Dubna, contains six separate records on the DELPHI experiment at LEP, the Fermi-surface dynamics of rotating nuclei, production of large samples of the silica dioxide aerogel in the 37-litre autoclave and test of its optical properties, preliminary radiation resource results on scintillating fibers, a new algorithm for the direct transformation method of time to digital with the high time resolution and development and design of analogue read-out electronics for HADES drift chamber system
International Nuclear Information System (INIS)
Baldin, A.M.; Bondarev, V.K.; Golovanov, L.B.
1977-01-01
Limit fragmentation of light nuclei (deuterium, helium) bombarded with 8,6 GeV/c protons was investigated. Fragments (pions, protons and deuterons) were detected within the emission angle 50-150 deg with regard to primary protons and within the pulse range 150-180 MeV/c. By the kinematics of collision of a primary proton with a target at rest the fragments observed correspond to a target mass upto 3 GeV. Thus, the data obtained correspond to teh cumulation upto the third order
Blandford, RD; Woltjer, L
1990-01-01
Starting with this volume, the Lecture Notes of the renowned Advanced Courses of the Swiss Society for Astrophysics and Astronomy will be published annually. In each course, three extensive lectures given by leading experts in their respective fields cover different and essential aspects of the subject. The 20th course, held at Les Diablerets in April 1990, dealt with current research on active galactic nuclei; it represents the most up-to-date views on the subject, presented with particular regard for clarity. The previous courses considered a wide variety of subjects, beginning with ""Theory
THREE-VALENCE-PARTICE NUCLEI IN THE 132Sn and 208 Pb REGIONS
International Nuclear Information System (INIS)
Benchikh, L.; Draoui, B.; Latfaoui, M.; Aissaoui, L.
2011-01-01
Full text: Among the nuclei of the nuclear charter, the nuclei around closed shells play a key role in understanding the effective interaction properties between nucleons far from the valley of stability; particulary, the nuclei of a few valence nucleons around doubly magic 208 28Pb126 and 132 50Sn82 nuclei. The interest of both regions 208Pb and 132Sn lies in the fact that there is a great similarity between their nuclear spectroscopic properties. The single energy gaps in both cases are comparable and the orbitals above and below these gaps are similarly ordered. Each single state in the region of 132Sn has its counterpart in that of 208Pb. An interesting predictive consequence, the interactions of the Sn region, difficult region to reach experimentally, can be estimated from their corresponding ones constructed to describe the nuclei of the Pb region. Because of the importance of the similarity existing between the spectroscopy of these two regions, we are interested in nuclei with three valence nucleons in the lead and Tin regions on the basis of experimental data (spin, parity and energy states). In this context, the theoretical study is conducted within the shell model using the MSDI interaction for the energy spectra calculations of the studied nuclei. The calculated results are in good agreement with the available experimental data and show evidence that a close resemblance between the spectroscopy of these two regions persists when moving away from the immediate neighbours of doubly magic 132Sn and 208Pb.
Dual origin of pairing in nuclei
Energy Technology Data Exchange (ETDEWEB)
Idini, A. [University of Jyvaskyla, Department of Physics (Finland); Potel, G. [Michigan State University, National Superconducting Cyclotron Laboratory (United States); Barranco, F. [Escuela Superior de Ingenieros, Universidad de Sevilla, Departamento de Fìsica Aplicada III (Spain); Vigezzi, E., E-mail: enrico.vigezzi@mi.infn.it [INFN Sezione di Milano (Italy); Broglia, R. A. [Università di Milano, Dipartimento di Fisica (Italy)
2016-11-15
The pairing correlations of the nucleus {sup 120}Sn are calculated by solving the Nambu–Gor’kov equations, including medium polarization effects resulting from the interweaving of quasiparticles, spin and density vibrations, taking into account, within the framework of nuclear field theory (NFT), processes leading to self-energy and vertex corrections and to the induced pairing interaction. From these results one can not only demonstrate the inevitability of the dual origin of pairing in nuclei, but also extract information which can be used at profit to quantitatively disentangle the contributions to the pairing gap Δ arising from the bare and from the induced pairing interaction. The first is the strong {sup 1}S{sub 0} short-range NN potential resulting from meson exchange between nucleons moving in time reversal states within an energy range of hundreds of MeV from the Fermi energy. The second results from the exchange of vibrational modes between nucleons moving within few MeV from the Fermi energy. Short- (v{sub p}{sup bare}) and long-range (v{sub p}{sup ind}) pairing interactions contribute essentially equally to nuclear Cooper pair stability. That is to the breaking of gauge invariance in open-shell superfluid nuclei and thus to the order parameter, namely to the ground state expectation value of the pair creation operator. In other words, to the emergent property of generalized rigidity in gauge space, and associated rotational bands and Cooper pair tunneling between members of these bands.
Approximate particle number projection in hot nuclei
International Nuclear Information System (INIS)
Kosov, D.S.; Vdovin, A.I.
1995-01-01
Heated finite systems like, e.g., hot atomic nuclei have to be described by the canonical partition function. But this is a quite difficult technical problem and, as a rule, the grand canonical partition function is used in the studies. As a result, some shortcomings of the theoretical description appear because of the thermal fluctuations of the number of particles. Moreover, in nuclei with pairing correlations the quantum number fluctuations are introduced by some approximate methods (e.g., by the standard BCS method). The exact particle number projection is very cumbersome and an approximate number projection method for T ≠ 0 basing on the formalism of thermo field dynamics is proposed. The idea of the Lipkin-Nogami method to perform any operator as a series in the number operator powers is used. The system of equations for the coefficients of this expansion is written and the solution of the system in the next approximation after the BCS one is obtained. The method which is of the 'projection after variation' type is applied to a degenerate single j-shell model. 14 refs., 1 tab
Dual origin of pairing in nuclei
Idini, A.; Potel, G.; Barranco, F.; Vigezzi, E.; Broglia, R. A.
2016-11-01
The pairing correlations of the nucleus 120Sn are calculated by solving the Nambu-Gor'kov equations, including medium polarization effects resulting from the interweaving of quasiparticles, spin and density vibrations, taking into account, within the framework of nuclear field theory (NFT), processes leading to self-energy and vertex corrections and to the induced pairing interaction. From these results one can not only demonstrate the inevitability of the dual origin of pairing in nuclei, but also extract information which can be used at profit to quantitatively disentangle the contributions to the pairing gap Δ arising from the bare and from the induced pairing interaction. The first is the strong 1 S 0 short-range NN potential resulting from meson exchange between nucleons moving in time reversal states within an energy range of hundreds of MeV from the Fermi energy. The second results from the exchange of vibrational modes between nucleons moving within few MeV from the Fermi energy. Short- ( v p bare) and long-range ( v p ind) pairing interactions contribute essentially equally to nuclear Cooper pair stability. That is to the breaking of gauge invariance in open-shell superfluid nuclei and thus to the order parameter, namely to the ground state expectation value of the pair creation operator. In other words, to the emergent property of generalized rigidity in gauge space, and associated rotational bands and Cooper pair tunneling between members of these bands.
Nuclear shell effects at high temperatures
International Nuclear Information System (INIS)
Davidson, N.J.; Miller, H.G.
1993-01-01
In discussing the disappearance of nuclear shell effects at high temperatures, it is important to distinguish between the ''smearing out'' of the single-particle spectrum with increasing temperature and the vanishing of shell related structures in many-body quantities such as the excitation energy per nucleon. We propose a semiempirical method to obtain an upper bound on the temperature required to smooth the single-particle spectrum, and point out that shell effects in many-body parameters may persist above this temperature. We find that the temperature required to smear out the single-particle spectrum is approximately 1 MeV for heavy nuclei (A approx-gt 150) and about 3--4 MeV for light nuclei (A approx-lt 50), in reasonable agreement with the estimate of 41/πA 1/3 obtained from calculations with harmonic oscillator potentials. These temperatures correspond to many-body excitation energies of approximately 20 and 60 MeV, respectively
Exotic nuclei and radioactive beams
International Nuclear Information System (INIS)
Chomaz, P.
1996-01-01
The Nuclei called exotic are all the nuclei that it is necessary to recreate in laboratory to study them. Their life time is too short -in relation to earth age- for it remains enough on earth. The researchers are going to have at their s disposal at GANIL (Caen) with the S.P.I.R.A.L. project, exotic nuclei beams and will study new kinds of nuclear reactions to better understand the atom nucleus. (N.C.). 2 refs., 9 figs
Isolation of Nuclei and Nucleoli.
Pendle, Alison F; Shaw, Peter J
2017-01-01
Here we describe methods for producing nuclei from Arabidopsis suspension cultures or root tips of Arabidopsis, wheat, or pea. These methods could be adapted for other species and cell types. The resulting nuclei can be further purified for use in biochemical or proteomic studies, or can be used for microscopy. We also describe how the nuclei can be used to obtain a preparation of nucleoli.
Stability of superheavy nuclei
Pomorski, K.; Nerlo-Pomorska, B.; Bartel, J.; Schmitt, C.
2018-03-01
The potential-energy surfaces of an extended set of heavy and superheavy even-even nuclei with 92 ≤Z ≤126 and isospins 40 ≤N -Z ≤74 are evaluated within the recently developed Fourier shape parametrization. Ground-state and decay properties are studied for 324 different even-even isotopes in a four-dimensional deformation space, defined by nonaxiality, quadrupole, octupole, and hexadecapole degrees of freedom. Nuclear deformation energies are evaluated in the framework of the macroscopic-microscopic approach, with the Lublin-Strasbourg drop model and a Yukawa-folded mean-field potential. The evolution of the ground-state equilibrium shape (and possible isomeric, metastable states) is studied as a function of Z and N . α -decay Q values and half-lives, as well as fission-barrier heights, are deduced. In order to understand the transition from asymmetric to symmetric fission along the Fm isotopic chain, the properties of all identified fission paths are investigated. Good agreement is found with experimental data wherever available. New interesting features about the population of different fission modes for nuclei beyond Fm are predicted.
Cluster structures in light nuclei
International Nuclear Information System (INIS)
Horiuchi, H.
2000-01-01
Complete text of publication follows. Clustering in neutron-rich nuclei is discussed. To understand the novel features (1,2,3) of the clustering in neutron-rich nuclei, the basic features of the clustering in stable nuclei (4) are briefly reviewed. In neutron-rich nuclei, the requirement of the stability of clusters is questioned and the threshold rule is no more obeyed. Examples of clustering in Be and B isotopes (4,5) are discussed in some detail. Possible existence of novel type of clustering near neutron dripline is suggested (1). (author)
International Nuclear Information System (INIS)
Kim, Yong Il; Im, Hyung Jun; Paeng, Jin Chul; Lee, Jae Sung; Eo, Jae Seon; Kim, Dong Hyun; Kim, Euishin E.; Kang, Keon Wook; Chung, June Key; Lee Dong Soo
2012-01-01
18 F FP CIT positron emission tomography (PET) is an effective imaging for dopamine transporters. In usual clinical practice, 18 F FP CIT PET is analyzed visually or quantified using manual delineation of a volume of interest (VOI) fir the stratum. in this study, we suggested and validated two simple quantitative methods based on automatic VOI delineation using statistical probabilistic anatomical mapping (SPAM) and isocontour margin setting. Seventy five 18 F FP CIT images acquired in routine clinical practice were used for this study. A study-specific image template was made and the subject images were normalized to the template. afterwards, uptakes in the striatal regions and cerebellum were quantified using probabilistic VOI based on SPAM. A quantitative parameter, Q SPAM, was calculated to simulate binding potential. additionally, the functional volume of each striatal region and its uptake were measured in automatically delineated VOI using isocontour margin setting. Uptake volume product(Q UVP) was calculated for each striatal region. Q SPAMa nd Q UVPw as calculated for each visual grading and the influence of cerebral atrophy on the measurements was tested. Image analyses were successful in all the cases. Both the Q SPAMa nd Q UVPw ere significantly different according to visual grading (0.001). The agreements of Q UVPa nd Q SPAMw ith visual grading were slight to fair for the caudate nucleus (K= 0.421 and 0.291, respectively) and good to prefect to the putamen (K=0.663 and 0.607, respectively). Also, Q SPAMa nd Q UVPh ad a significant correlation with each other (0.001). Cerebral atrophy made a significant difference in Q SPAMa nd Q UVPo f the caudate nuclei regions with decreased 18 F FP CIT uptake. Simple quantitative measurements of Q SPAMa nd Q UVPs howed acceptable agreement with visual grad-ing. although Q SPAMi n some group may be influenced by cerebral atrophy, these simple methods are expected to be effective in the quantitative analysis of F FP
Meson-exchange forces and medium polarization in finite nuclei
International Nuclear Information System (INIS)
Hengeveld, W.
1986-01-01
A G-matrix, derived from a meson-exchange potential in nuclear matter, is applied to finite, semi-magic nuclei. For the open shell the broken-pair model, which can accomodate many particle levels, is used. The excitations of the closed shell are treated as particle-hole states. Energy spectra and electromagnetic transition densities are calculated for 88 Sr and 58 Ni. The standard random-phase approximation for finite systems is extended by including the effects of the exchange of the RPA phonons in the residual interaction selfconsistently. It is shown that this particle-hole interaction is strongly energy dependent due to the presence of poles corresponding to 2p-2h (and more complex) excitations. The RPA eigenvalue problem with this energy-dependent residual interaction also provides solutions for these predominantly 2p2h-like states. In addition a modified normalization condition is obtained. This scheme is applied to 56 Ni( 56 Co) in a large configuration space using a residual interaction of the G-matrix type. The effect of dynamic medium polarization on the properties of giant resonances is illustrated for the case of A=48 nuclei. A large fragmentation of the monopole strength is calculated, which is in accordance with the non-observation of the GMR in light nuclei. Properties of A=48 nuclei are computed with an interaction deduced from the NN scattering data without introduction of additional parameters. The role of medium polarization is illustrated for spectra and (e,e') form factors. It is shown how medium polarization induces a coupling between excitations in even-even and in the adjacent odd-odd nuclei. (Auth.)
Level structures in Yb nuclei far from stable nuclei
International Nuclear Information System (INIS)
Hashizume, Akira
1982-01-01
Applying n-γ, γ-γ coincidence techniques, the excited levels in 158 Yb and in 157 Yb nuclei were studied. Stress is placed ona neutron detection technique to assign (HI,xn) reactions which produce the nuclei far from β stability line. (author)
Self-consistent study of nuclei far from stability with the energy density method
Tondeur, F
1981-01-01
The self-consistent energy density method has been shown to give good results with a small number of parameters for the calculation of nuclear masses, radii, deformations, neutron skins, shell and sub- shell effects. It is here used to study the properties of nuclei far from stability, like densities, shell structure, even-odd mass differences, single-particle potentials and nuclear deformations. A few possible consequences of the results for astrophysical problems are briefly considered. The predictions of the model in the super- heavy region are summarised. (34 refs).
Atomic mass prediction from the mass formula with empirical shell terms
International Nuclear Information System (INIS)
Uno, Masahiro; Yamada, Masami
1982-08-01
The mass-excess prediction of about 8000 nuclides was calculated from two types of the atomic mass formulas with empirical shell terms of Uno and Yamada. The theoretical errors to accompany the calculated mass excess are also presented. These errors have been obtained by a new statistical method. The mass-excess prediction includes the term of the gross feature of a nuclear mass surface, the shell terms and a small correction term for odd-odd nuclei. Two functional forms for the shell terms were used. The first is the constant form, and the sencond is the linear form. In determining the values of shell parameters, only the data of even-even and odd-A nuclei were used. A new statistical method was applied, in which the error inherent to the mass formula was taken account. The obtained shell parameters and the values of mass excess are shown in tables. (Kato, T.)
Deriving the nuclear shell model from first principles
Barrett, Bruce R.; Dikmen, Erdal; Vary, James P.; Maris, Pieter; Shirokov, Andrey M.; Lisetskiy, Alexander F.
2014-09-01
The results of an 18-nucleon No Core Shell Model calculation, performed in a large basis space using a bare, soft NN interaction, can be projected into the 0 ℏω space, i.e., the sd -shell. Because the 16 nucleons in the 16O core are frozen in the 0 ℏω space, all the correlations of the 18-nucleon system are captured by the two valence, sd -shell nucleons. By the projection, we obtain microscopically the sd -shell 2-body effective interactions, the core energy and the sd -shell s.p. energies. Thus, the input for standard shell-model calculations can be determined microscopically by this approach. If the same procedure is then applied to 19-nucleon systems, the sd -shell 3-body effective interactions can also be obtained, indicating the importance of these 3-body effective interactions relative to the 2-body effective interactions. Applications to A = 19 and heavier nuclei with different intrinsic NN interactions will be presented and discussed. The results of an 18-nucleon No Core Shell Model calculation, performed in a large basis space using a bare, soft NN interaction, can be projected into the 0 ℏω space, i.e., the sd -shell. Because the 16 nucleons in the 16O core are frozen in the 0 ℏω space, all the correlations of the 18-nucleon system are captured by the two valence, sd -shell nucleons. By the projection, we obtain microscopically the sd -shell 2-body effective interactions, the core energy and the sd -shell s.p. energies. Thus, the input for standard shell-model calculations can be determined microscopically by this approach. If the same procedure is then applied to 19-nucleon systems, the sd -shell 3-body effective interactions can also be obtained, indicating the importance of these 3-body effective interactions relative to the 2-body effective interactions. Applications to A = 19 and heavier nuclei with different intrinsic NN interactions will be presented and discussed. Supported by the US NSF under Grant No. 0854912, the US DOE under
Growth of electron plasma waves above and below f(p) in the electron foreshock
Cairns, Iver H.; Fung, Shing F.
1988-01-01
This paper investigates the conditions required for electron beams to drive wave growth significantly above and below the electron plasma frequency, f(p), by numerically solving the linear dispersion equation. It is shown that kinetic growth well below f(p) may occur over a broad range of frequencies due to the beam instability, when the electron beam is slow, dilute, and relatively cold. Alternatively, a cold or sharp feature at low parallel velocities in the distribution function may drive kinetic growth significantly below f(p). Kinetic broadband growth significantly above f(p) is explained in terms of faster warmer beams. A unified qualitative theory for the narrow-band and broad-band waves is proposed.
Identification of a functional nuclear export signal in the green fluorescent protein asFP499
International Nuclear Information System (INIS)
Mustafa, Huseyin; Strasser, Bernd; Rauth, Sabine; Irving, Robert A.; Wark, Kim L.
2006-01-01
The green fluorescent protein (GFP) asFP499 from Anemonia sulcata is a distant homologue of the GFP from Aequorea victoria. We cloned the asFP499 gene into a mammalian expression vector and showed that this protein was expressed in the human lymphoblast cell line Ramos RA1 and in the embryonic kidney 293T cell line (HEK 293T). In HEK 293T cells, asFP499 was localized mainly in the cytoplasm, suggesting that the protein was excluded from the nucleus. We identified 194 LRMEKLNI 201 as a candidate nuclear export signal in asFP499 and mutated the isoleucine at position 201 to an alanine. Unlike the wildtype form, the mutant protein was distributed throughout the cytoplasm and nucleus. This is First report of a GFP that contains a functional NES
Performance of 6FDA–6FpDA polyimide for propylene/propane separations
Das, Mita; Koros, William J.
2010-01-01
This work addresses the challenges faced by previous researchers with 6FDA-6FpDA polyimide for propylene/propane separations due to plasticization. A study of film annealing temperature is reported to optimize plasticization suppression in elevated
Electron scattering off nuclei
International Nuclear Information System (INIS)
Gattone, A.O.
1989-01-01
Two recently developed aspects related to the scattering of electrons off nuclei are presented. On the one hand, a model is introduced which emphasizes the relativistic aspects of the problem in the impulse approximation, by demanding strict maintenance of the algebra of the Poincare group. On the other hand, the second model aims at a more sophisticated description of the nuclear response in the case of collective excitations. Basically, it utilizes the RPA formalism with a new development which enables a more careful treatment of the states in the continuum as is the case for the giant resonances. Applications of both models to the description of elastic scattering, inelastic scattering to discrete levels, giant resonances and the quasi-elastic region are discussed. (Author) [es
Antideuteron annihilation on nuclei
International Nuclear Information System (INIS)
Cugnon, J.
1992-01-01
An investigation of antideuteron annihilation on nuclei within an intranuclear cascade (INC) model is presented. Two models are set up to describe the annihilation itself, which either implies the antideuteron as a whole and occurs at a single point, or which may be considered as two independent nucleon-antinucleon annihilation occurring at different points and different times. Particular attention is paid to the energy transferred from the pions issued from the annihilation to the nuclear system and to the possibility of having a multifragmentation of the target. The latter feature is investigated within a percolation model. The pion distribution and the energy distribution are also discussed. Predictions of proton multiplicity distributions are compared with experiment. (orig.)
International Nuclear Information System (INIS)
2002-01-01
The present collection of letters from JINR, Dubna, contains ten separate records on Wien filter using in exploring on low-energy radioactive nuclei, memory effects in dissipative nucleus-nucleus collision, topological charge and topological susceptibility in connection with translation and gauge invariance, solutions of the multitime Dirac equation, the maximum entropy technique. System's statistical description, the charged conductor inside dielectric. Solution of boundary condition by means of auxiliary charges and the method of linear algebraic equations, optical constants of the TGS single crystal irradiated by power pulsed electron beam, interatomic pair potential and n-e amplitude from slow neutron scattering by noble gases, the two-coordinate multiwire proportional chamber of the high spatial resolution and neutron drip line in the region of O-Mg isotopes
International Nuclear Information System (INIS)
2000-01-01
The present collection of letters from JINR, Dubna, contains seven separate records on the integral representation for structure functions and target mass effects, multiscale properties of DNA primary structure including cross-scale correlations, dissipative evolution of the elementary act, the fine structure of the M T =1 Gamow-Teller resonance in 147g Tb→ 147 Gd β + /EC decay, the behaviour of the TVO temperature sensors in the magnetic fields, a fast method for searching for tracks in multilayer drift chambers of HADES spectrometer, a novel approach to particle track etching including surfactant enhanced control of pore morphology, azimuthal correlations of secondary particles in 32 S induced interactions with Ag(Br) nuclei at 4.5 GeV/ c/ nucleon
International Nuclear Information System (INIS)
Xu, Renxin
2011-01-01
What is the real nature of pulsars? This is essentially a question of the fundamental strong interaction between quarks at low-energy scale and hence of the non-perturbative quantum chromo-dynamics, the solution of which would certainly be meaningful for us to understand one of the seven millennium prize problems (i.e., "Yang-Mills Theory") named by the Clay Mathematical Institute. After a historical note, it is argued here that a pulsar is very similar to an extremely big nucleus, but is a little bit different from the gigantic nucleus speculated 80 years ago by L. Landau. The paper demonstrates the similarity between pulsars and gigantic nuclei from both points of view: the different manifestations of compact stars and the general behavior of the strong interaction. (author)
Following the pioneering discovery of alpha clustering and of molecular resonances, the field of nuclear clustering is today one of those domains of heavy-ion nuclear physics that faces the greatest challenges, yet also contains the greatest opportunities. After many summer schools and workshops, in particular over the last decade, the community of nuclear molecular physicists has decided to collaborate in producing a comprehensive collection of lectures and tutorial reviews covering the field. This third volume follows the successful Lect. Notes Phys. 818 (Vol. 1) and 848 (Vol. 2), and comprises six extensive lectures covering the following topics: - Gamma Rays and Molecular Structure - Faddeev Equation Approach for Three Cluster Nuclear Reactions - Tomography of the Cluster Structure of Light Nuclei Via Relativistic Dissociation - Clustering Effects Within the Dinuclear Model : From Light to Hyper-heavy Molecules in Dynamical Mean-field Approach - Clusterization in Ternary Fission - Clusters in Light N...
The internal conversion and e+e- - pairs creation from the heated nuclei
International Nuclear Information System (INIS)
Fedotkin, S.N.; Kolomietz, V.M.
1995-01-01
General expression for the probabilities of the atomic shell ionization and e + e - -pairs creation at the heated nuclei are found. The spectral distributions of the positrons and conversion electron are investigated in the case of the nuclear E1-transitions
Evidence for two-dimensional ising structure in atomic nuclei
International Nuclear Information System (INIS)
MacGregor, M.H.
1976-01-01
Although the unpaired nucleons in an atomic nucleus exhibit pronounced shell-model-like behavior, the situation with respect to the paired-off ''core region'' nucleons is considerably more obscure. Several recent ''multi-alpha knockout'' and ''quasi-fission'' experiments indicate that nucleon clustering is prevalent throughout the core region of the nucleus; this same conclusion is suggested by nuclear-binding-energy systematics, by the evidence for a ''neutron halo'' in heavy nuclei and by the magnetic-moment systematics of low-mass odd-A nuclei. A number of arguments suggests, in turn, that this nucleon clustering is not spherical or spheroidal in shape, as has generally been assumed, but instead is in the form of two-dimensional Ising-like layers, with the layers arrayed perpendicular to the symmetry axis of the nucleus. The effects of this two-dimensional layering are observed most clearly in low-energy-induced fission, where nuclei with an even (odd) number of Ising layers fission symmetrically (asymmetrically). This picture of the nucleus gives an immediate quantitative explanation for the observed asymmetry in the fission of uranium, and also for the transition from symmetric to asymmetric and back to symmetric fission as the atomic number of the fissioning nuclues increase from A = 197 up to A = 258. These results suggest that, in the shell model formulation of the atomic nucleus, the basis states for the paired-off nucleon core region should be modified so as to contain laminar nucleon cluster correlations
Collective excitations in nuclei
International Nuclear Information System (INIS)
Chomaz, Ph.
1998-01-01
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)
International Nuclear Information System (INIS)
Casten, R.F.; Warner, D.D.
1982-01-01
The structure and characteristic properties and predictions of the IBA in deformed nuclei are reviewed, and compared with experiment, in particular for 168 Er. Overall, excellent agreement, with a minimum of free parameters (in effect, two, neglecting scale factors on energy differences), was obtained. A particularly surprising, and unavoidable, prediction is that of strong β → γ transitions, a feature characteristically absent in the geometrical model, but manifest empirically. Some discrepancies were also noted, principally for the K=4 excitation, and the detailed magnitudes of some specific B(E2) values. Considerable attention is paid to analyzing the structure of the IBA states and their relation to geometric models. The bandmixing formalism was studied to interpret both the aforementioned discrepancies and the origin of the β → γ transitions. The IBA states, extremely complex in the usual SU(5) basis, are transformed to the SU(3) basis, as is the interaction Hamiltonian. The IBA wave functions appear with much simplified structure in this way as does the structure of the associated B(E2) values. The nature of the symmetry breaking of SU(3) for actual deformed nuclei is seen to be predominantly ΔK=0 mixing. A modified, and more consistent, formalism for the IBA-1 is introduced which is simpler, has fewer free parameters (in effect, one, neglecting scale factors on energy differences), is in at least as good agreement with experiment as the earlier formalism, contains a special case of the 0(6) limit which corresponds to that known empirically, and appears to have a close relationship to the IBA-2. The new formalism facilitates the construction of contour plots of various observables (e.g., energy or B(E2) ratios) as functions of N and chi/sub Q/ which allow the parameter-free discussion of qualitative trajectories or systematics
Collective excitations in nuclei
Energy Technology Data Exchange (ETDEWEB)
Chomaz, Ph. [Grand Accelerateur National d`Ions Lourds (GANIL), 14 - Caen (France); Collaboration: La Direction des Sciences de la Matiere du CEA (FR); Le Fonds National de la Recherche Scientifique de Belgique (BE)
1998-12-31
The properties of the nucleus cannot be reduced to the properties of its constituents: it is a complex system. The fact that many properties of the nucleus are consequences of the existence of mean-field potential is a manifestation of this complexity. In particular, the nucleons can thus self-organize in collective motions such as giant resonances. Therefore the study of this collective motions is a very good tool to understand the properties of the nucleus itself. The purpose of this article is to stress some aspects of these collective vibrations. We have studied how an ensemble of fermions as the nucleus can self-organize in collective vibrations which are behaving like a gas of bosons in weak interaction. Understanding of these phenomena remains one of the important subjects of actuality in the context of quantal systems in strong interaction. In particular, the study of the states with one or two vibration quanta provides a direct information on the structure of nuclei close to their ground states. Moreover, some collective states appear to be very robust against the onset of chaos. This is the case of the hot giant dipole built on top of a hot nucleus which seems to survive up to rather high temperatures. Their sudden disappearance is still a subject of controversy. It may be that the mean-field and the associated collective states are playing a crucial role also in catastrophic processes such as the phase-transitions. Indeed, when the system is diluted the collective vibrations may become unstable and it seems that these unstable modes provide a natural explanation to the self organization of the system in drops. Finally, considering the diversity of the different structures of exotic nuclei one may expect new vibration types. All these studies are showing the diversity of the collective motions of strongly correlated quantum systems such as the nucleus but many open questions remain to be solved. (authors) 304 refs., 53 figs., 5 tabs.
Deformation and shell effects in nuclear mass formulas
International Nuclear Information System (INIS)
Barbero, César; Hirsch, Jorge G.; Mariano, Alejandro E.
2012-01-01
We analyze the ability of three different Liquid Drop Mass (LDM) formulas to describe nuclear masses for nuclei in various deformation regions. Separating the 2149 measured nuclear species into eight sets with similar quadrupole deformations, we show that the masses of prolate deformed nuclei are better described than those of spherical ones. In fact, the prolate deformed nuclei are fitted with an RMS smaller than 750 keV, while for spherical and semi-magic species the RMS is always larger than 2000 keV. These results are found to be independent of pairing. It is also shown that the macroscopic sector of the Duflo–Zuker (DZ) mass model reproduces shell effects, while most of the deformation dependence is lost and the RMS is larger than in any LDM. Adding to the LDM the microscopically motivated DZ master terms introduces the shell effects, allowing for a significant reduction in the RMS of the fit but still exhibiting a better description of prolate deformed nuclei. The inclusion of shell effects following the Interacting Boson Model's ideas produces similar results.
Deformation and shell effects in nuclear mass formulas
Energy Technology Data Exchange (ETDEWEB)
Barbero, Cesar [Departamento de Fisica, Universidad Nacional de La Plata, C.C. 67, 1900 La Plata (Argentina); Instituto de Fisica La Plata, CONICET, 1900 La Plata (Argentina); Hirsch, Jorge G., E-mail: hirsch@nucleares.unam.mx [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, 04510 Mexico D.F. (Mexico); Mariano, Alejandro E. [Departamento de Fisica, Universidad Nacional de La Plata, C.C. 67, 1900 La Plata (Argentina); Instituto de Fisica La Plata, CONICET, 1900 La Plata (Argentina)
2012-01-15
We analyze the ability of three different Liquid Drop Mass (LDM) formulas to describe nuclear masses for nuclei in various deformation regions. Separating the 2149 measured nuclear species into eight sets with similar quadrupole deformations, we show that the masses of prolate deformed nuclei are better described than those of spherical ones. In fact, the prolate deformed nuclei are fitted with an RMS smaller than 750 keV, while for spherical and semi-magic species the RMS is always larger than 2000 keV. These results are found to be independent of pairing. It is also shown that the macroscopic sector of the Duflo-Zuker (DZ) mass model reproduces shell effects, while most of the deformation dependence is lost and the RMS is larger than in any LDM. Adding to the LDM the microscopically motivated DZ master terms introduces the shell effects, allowing for a significant reduction in the RMS of the fit but still exhibiting a better description of prolate deformed nuclei. The inclusion of shell effects following the Interacting Boson Model's ideas produces similar results.
Mass-spectrometer of knock-on nuclei for reactor 'Pik'
International Nuclear Information System (INIS)
Begzhanov, P.B.; Nazarov, A.G.; Petrov, G.A.; Pikul', V.P.
1999-01-01
For reactor 'Pik' (that is being built in St. Petersburg Institute of Nuclear Physics) there was designed a universal two shoulder mass-spectrometer for non-decelerated fission products (FP) of nuclei. The spectrometer helps to obtain different values of linear magnification, dispersion, aberration coefficients and transmission without making structural changes in the device. To separate FP for one shoulder of spectrometer we chose ion-optical scheme (IOS) consisting of three electrostatic analyzers and three-sectional magnet 'JOSEF' that had high dispersion by masses at small deflection radius. IOS calculations of mass-spectrometer were performed with the help of program TRANSVOL (transfer of phase volume) designed basing on TRIO program. The program allows calculating of complete IOS transmission with taking into account elements aperture and beam officering
Genetics, structure, and prevalence of FP967 (CDC Triffid) T-DNA in flax.
Young, Lester; Hammerlindl, Joseph; Babic, Vivijan; McLeod, Jamille; Sharpe, Andrew; Matsalla, Chad; Bekkaoui, Faouzi; Marquess, Leigh; Booker, Helen M
2015-01-01
The detection of T-DNA from a genetically modified flaxseed line (FP967, formally CDC Triffid) in a shipment of Canadian flaxseed exported to Europe resulted in a large decrease in the amount of flax planted in Canada. The Canadian flaxseed industry undertook major changes to ensure the removal of FP967 from the supply chain. This study aimed to resolve the genetics and structure of the FP967 transfer DNA (T-DNA). The FP967 T-DNA is thought to be inserted in at single genomic locus. The junction between the T-DNA and genomic DNA consisted of two inverted Right Borders with no Left Border (LB) flanking genomic DNA sequences recovered. This information was used to develop an event-specific quantitative PCR (qPCR) assay. This assay and an existing assay specific to the T-DNA construct were used to determine the genetics and prevalence of the FP967 T-DNA. These data supported the hypothesis that the T-DNA is present at a single location in the genome. The FP967 T-DNA is present at a low level (between 0.01 and 0.1%) in breeder seed lots from 2009 and 2010. None of the 11,000 and 16,000 lines selected for advancement through the Flax Breeding Program in 2010 and 2011, respectively, tested positive for the FP967 T-DNA, however. Most of the FP967 T-DNA sequence was resolved via PCR cloning and next generation sequencing. A 3,720 bp duplication of an internal portion of the T-DNA (including a Right Border) was discovered between the flanking genomic DNA and the LB. An event-specific assay, SAT2-LB, was developed for the junction between this repeat and the LB.
TRAC-PF1 code assessment using OECD LOFT LP-FP-1 experiment
International Nuclear Information System (INIS)
Barbero, F.J.
1992-04-01
This report assesses thermal-hydraulic aspects of LOFT LP-FP-1 experiment making use of TRAC-PF1/MOD1. LP-FP-1 experiment studies the system thermal-hydraulic and core thermal response for initial and boundary conditions similar to a large-break design basis LOCA leading to fission product release from the fuel cladding gap region. It also assesses the fission product retention effectiveness of the PWR-ECCS in best estimate conditions
Spectroscopy of few-particle nuclei around magic 132Sn from fission product γ-ray studies
International Nuclear Information System (INIS)
Zhang, C. T.
1998-01-01
We are studying the yrast structure of very neutron-rich nuclei around doubly magic 132 Sn by analyzing fission product γ-ray data from a 248 Cm source at Eurogam II. Yrast cascades in several few-valence-particle nuclei have been identified through γγ cross coincidences with their complementary fission partners. Results for two-valence-particle nuclei 132 Sb, 134 Te, 134 Sb and 134 Sn provide empirical nucleon-nucleon interactions which, combined with single-particle energies already known in the one-particle nuclei, are essential for shell-model analysis in this region. Findings for the N = 82 nuclei 134 Te and 135 I have now been extended to the four-proton nucleus 136 Xe. Results for the two-neutron nucleus 134 Sn and the N = 83 isotones 134 Sb, 135 Te and 135 I open up the spectroscopy of nuclei in the northeast quadrant above 132 Sn
Energy Technology Data Exchange (ETDEWEB)
Dobaczewski, J [Warsaw Univ., Institute of Theoretical Physics (Poland); Blumenfeld, Y; Flocard, H; Garcia Borge, M J; Nowacki, F; Rombouts, S; Theisen, Ch; Marques, F M; Lacroix, D; Dessagne, P; Gaeggeler, H
2002-07-01
This document gathers the lectures made at the Joliot Curie international summer school in 2002 whose theme that year was exotic nuclei. There were 11 contributions whose titles are: 1) interactions, symmetry breaking and effective fields from quarks to nuclei; 2) status and perspectives for the study of exotic nuclei: experimental aspects; 3) the pairing interaction and the N = Z nuclei; 4) borders of stability region and exotic decays; 5) shell structure of nuclei: from stability to decay; 6) variational approach of system with a few nucleons; 7) from heavy to super-heavy nuclei; 8) halos, molecules and multi-neutrons; 9) macroscopic approaches for fusion reactions; 10) beta decay: a tool for spectroscopy; 11) the gas phase chemistry of super-heavy elements.
Problem of ''deformed'' superheavy nuclei
International Nuclear Information System (INIS)
Sobiczewski, A.; Patyk, Z.; Muntian, I.
2000-08-01
Problem of experimental confirmation of deformed shapes of superheavy nuclei situated in the neighbourhood of 270 Hs is discussed. Measurement of the energy E 2+ of the lowest 2+ state in even-even species of these nuclei is considered as a method for this confirmation. The energy is calculated in the cranking approximation for heavy and superheavy nuclei. The branching ratio p 2+ /p 0+ between α decay of a nucleus to this lowest 2+ state and to the ground state 0+ of its daughter is also calculated for these nuclei. The results indicate that a measurement of the energy E 2+ for some superheavy nuclei by electron or α spectroscopy is a promising method for the confirmation of their deformed shapes. (orig.)
Directory of Open Access Journals (Sweden)
Holt Roy J.
2016-01-01
Full Text Available Electron scattering at very high Bjorken x from hadrons provides an excellent test of models, has an important role in high energy physics, and from nuclei, provides a window into short range correlations. Light nuclei have a key role because of the relatively well-known nuclear structure. The development of a novel tritium target for Jefferson Lab has led to renewed interest in the mass three system. For example, deep inelastic scattering experiments in the light nuclei provide a powerful means to determine the neutron structure function. The isospin dependence of electron scattering from mass-3 nuclei provide information on short range correlations in nuclei. The program using the new tritium target will be presented along with a summary of other experiments aimed at revealing the large-x structure of the nucleon.
Study of the N=40 shell by using Coulomb excitation
International Nuclear Information System (INIS)
Leenhardt, St.
2000-01-01
Two Coulomb excitation experiments on neutron rich exotic nuclei have been performed at GANIL. They allowed the measurement of the reduced transition probability B(E2) (from ground state to first excited state) of some nuclei around N = 40. This number, 40, is a half-magic number in the shell model. For nuclei with an important neutron excess, it is predicted that the shell closure is stronger at N = 40. The B(E2) is a good tool for testing this growing. We have measured, by using the LISE3 spectrometer and a γ multidetector, B(E2) of 68 Ni, 66 Ni and 72 Zn, unknown till now. We have used for the first time segmented germanium 'clovers' detector, for photon detection (v/c∼0.3). Results confirm the strong shell effect for 68 Ni. Indeed 68 Ni was shown to be the Nickel isotope with the lowest value of B(E2), and hence the most rigid isotope. Nevertheless it seems that the shell effect at N = 40 decreases rapidly, for other isotopes very close to 68 Ni(Z = 28) and N = 40). (authors)
Simulation of COMEDIE Fission Product Plateout Experiment Using GAMMA-FP
International Nuclear Information System (INIS)
Tak, Nam-il; Yoon, Churl
2014-01-01
FThis phenomenon is particularly important under a VHTR design with vented low pressure confinement (VLPC), because the vent allows the prompt release of fission products accumulated within the primary circuit to environment during an initial blow-down phase after pipe break accidents. In order to analyze the fission product plateout, an numerical model was developed by Yoo et al. and incorporated into the GAMMA-FP code in the past. The GAMMA-FP model was validated against two experiment data, i.e., VAMPYR-1 and OGL, during the development phase. One of the well-known experiments for fission product plateout is the COMEDIE experiment. In this work, the COMEDIE experiment has been simulated using the GAMMA-FP code to investigate the reliability and applicability of the plateout model of GAMMA-FP. The COMEDIE experiment for fission product plateout was simulated using the GAMMA-FP code in this work. A good agreement was achieved between the measured and predicted plateout activities. The existing solution scheme was modified to allow larger time step size for fission product analysis in order to speed-up the computational time. Nevertheless, the modification of the existing numerical model of GAMMA-FP is necessary when a simulation capability of a long duration of plateout period (e.g., 60 years) is targeted
New directions at UNISOR and the importance of reinforcing spherical and deformed shell gaps
International Nuclear Information System (INIS)
Hamilton, J.H.
1985-01-01
An on-line nuclear orientation facility under construction for UNISOR is described. The strong competition between shell gaps at spherical, prolate and oblate deformation is shown to give rise to various structures from spherical double closed shell, to coexisting near-spherical and deformed shapes to deformed double closed shell nuclei in the region of A = 70-104. The importance of the reinforcing of the shape driving forces when the nucleus has shell gaps for the protons and neutrons at the same deformation on nuclear shapes and the switching of magic numbers is described
Quartetting in even-even and odd-odd N=Z nuclei
Sambataro, M.; Sandulescu, N.
2018-02-01
We report on a microscopic description of even-even N = Z nuclei in a formalism of quartets. Quartets are four-body correlated structures characterized by isospin T and angular momentum J. We show that the ground state correlations induced by a realistic shell model interaction can be well accounted for in terms of a restricted set of T = 0 low-J quartets, the J = 0 one playing by far a leading role among them. A conceptually similar description of odd-odd self-conjugate nuclei is given in terms of two distinct families of building blocks, one formed by the same T = 0 quartets employed for the even-even systems and the other by collective pairs with either T = 0 or T = 1. Some applications of this formalism are discussed for nuclei in the sd shell.
Carbonate Precipitates During Heat Evolution in FP-Type Cells
International Nuclear Information System (INIS)
Bruce L. Cain
2000-01-01
In previous work, we reported measurement of large amounts of heat generated during experiments using an FP-type open cell with concentrated LiOH/D 2 O electrolytes and thin-film Pd cathodes. During the heat evolution in several runs, which produced >100 W for more than 20 h, we consistently observed the concomitant evolution of gases from the electrolyte and the precipitation of large amounts of lithium carbonate. The carbonate production was clearly visible during production of heat, creating an opaque electrolyte even during long periods with no electrolysis current. These results indicated an unusual chemical reaction, either catalyzed by the heating process or possibly creating the heat itself. The total energy released during the earlier experiments was ∼7 MJ, while the heat of formation for the lithium carbonate in the cell was only 0.8 MJ. Hence, only ∼10% of the heat signatures from these experiments can be attributed to the precipitate formation, the balance of the heat presumably arising from nonchemical sources in the cells. The earlier experiments that produced heat also suffered from problems of reproducibility, with only 5 of 38 runs producing any heat at all. The unsuccessful runs also did not produce precipitates, and the only gas produced in these cells was due to the normal electrolysis of D 2 O to produce oxygen and deuterium in the electrodes. Recent work has focused on recreating the chemical precipitation reaction, in efforts to understand and/or trigger the heat production process. With findings from these experiments, new experiments were conducted using larger (1 L LiOH/D 2 O) cells with Pt anodes and Pd film cathodes immersed but left open-circuited. After the addition of H 2 O 2 , and subsequent heating and cooling, these cells visually reproduced the precipitation and gas evolution of the earlier heat-producing runs. However, these new runs only produced a few watts of power for several minutes, consistent with the normal exothermal
Preliminary results of the PREFER FP7 Project
Fusilli, Lorenzo; Laneve, Giovanni; De Bonis, Roberto; Sebastian, Ana; Ferrucci, Fabrizio; Oliveira, Sandra
2014-05-01
The need to improve the information and intelligence support for forest fire prevention is widely recognized. Fire prevention is still the most cost-effective strategy when compared to firefighting and extinguishing that are costly, local, and triggered only in response to already ongoing crises. PREFER project, funded under the EU FP7 (G.A. 312931), intends to contribute at responding to such a pragmatic need of southern Europe's forests by: providing timely information products based on the exploitation of all available spacecraft sensors, offering a portfolio of products focused on pre- and post-crisis forest fire emergency, suitable for the users in the different countries of the European Mediterranean area. The PREFER Service portfolio consists of two main services: 1. Information Support to Fire Preparedness/Prevention Phase" (ISP) Service 2. Information Support to Fire Recovery/Reconstruction Phase" (ISR) Service This service is already at an advanced stage having completed the first year of activity. During this time several products have been consolidated: seasonal fuel maps; daily and seasonal fire hazard maps; seasonal risk maps; prescribed fire maps. This paper aims at presenting the preliminary results of the research activity carried out in the framework of the PREFER project, focusing, in particular, on these recalled above. As for Fire Risk and Hazard assessment, many indexes have been developed in the last years. Hardly any of them uses data derived from satellite images. The FPI index is an exception to this rule which, in addition, makes use of meteorological data. In spite of being a very complete index, the FPI still allows room for improvement which justify the interest of PREFER in it. PREFER's innovative approach to FPI will allow taking into account the effect of solar illumination conditions in determining the humidity present in the dead vegetation, and therefore its proneness to burn. PREFER innovation also focus in allowing the index to
International Nuclear Information System (INIS)
2001-01-01
The present collection of letters from JINR, Dubna, contains eight separate records on status of 116 Cd double β decay study with 116 CdWO 4 scintillators, new limits on 2β processes in 40 Ca and 46 Ca by using low radioactive CaF 2 (Eu) crystal scintillators, the single state dominance in 2νββ-decay transitions to excited 0 + and 2 + final states, present status of the MONOLITH project, technique of neutrino-induced muon detection on the Earth surface, high-sensitive spectrometer of fast neutrons and the results of fast neutron background flux measurements at the gallium-germanium solar neutrino experiment (SAGE), new experimental limits on the electron stability and excitation of nuclear levels in 23 Na, 127 I and 129 Xe induced by the electron decay on the atomic shell and element-loaded organic scintillators for neutron and neutrino physics
Fusion probability and survivability in estimates of heaviest nuclei production
International Nuclear Information System (INIS)
Sagaidak, Roman
2012-01-01
. Examples of the P fus values derived with the capture-fission and ER cross-sections obtained recently for asymmetric projectile-target systems are shown. Data on the ER production in different fusion-evaporation reactions leading to the very heavy compound nuclei with ZCN ≥ 100 are considered and discussed in detail. Considering the fusion probability and survivability for the heaviest nuclei with Z > 108, one should bear in mind that the macroscopic component of fission barriers disappears as the shell-stabilized SHE region is approached. Thus the calculated survivability of nuclei produced in the 48 Ca reactions induced on actinide targets depends mainly on the microscopic (shell) corrections to nuclear masses used in calculations
Probable alpha and 14C cluster emission from hyper Ac nuclei
International Nuclear Information System (INIS)
Santhosh, K.P.
2013-01-01
A systematic study on the probability for the emission of 4 He and 14 C cluster from hyper Λ 207-234 Ac and non-strange normal 207-234 Ac nuclei are performed for the first time using our fission model, the Coulomb and proximity potential model (CPPM). The predicted half lives show that hyper Λ 207-234 Ac nuclei are unstable against 4 He emission and 14 C emission from hyper Λ 217-228 Ac are favorable for measurement. Our study also show that hyper Λ 207-234 Ac are stable against hyper Λ 4 He and Λ 14 C emission. The role of neutron shell closure (N = 126) in hyper Λ 214 Fr daughter and role of proton/neutron shell closure (Z ∼ 82, N = 126) in hyper Λ 210 Bi daughter are also revealed. As hyper-nuclei decays to normal nuclei by mesonic/non-mesonic decay and since most of the predicted half lives for 4 He and 14 C emission from normal Ac nuclei are favourable for measurement, we presume that alpha and 14 C cluster emission from hyper Ac nuclei can be detected in laboratory in a cascade (two-step) process. (orig.)
Quantum phase transitions and collective enhancement of level density in odd–A and odd–odd nuclei
Energy Technology Data Exchange (ETDEWEB)
Karampagia, S., E-mail: karampag@nscl.msu.edu [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824-1321 (United States); Renzaglia, A. [Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824-1321 (United States); Zelevinsky, V. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824-1321 (United States); Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824-1321 (United States)
2017-06-15
The nuclear shell model assumes an effective mean-field plus interaction Hamiltonian in a specific configuration space. We want to understand how various interaction matrix elements affect the observables, the collectivity in nuclei and the nuclear level density for odd–A and odd–odd nuclei. Using the sd and pf shells, we vary specific groups of matrix elements and study the evolution of energy levels, transition rates and the level density. In all cases studied, a transition between a “normal” and a collective phase is induced, accompanied by an enhancement of the level density in the collective phase. In distinction to neighboring even–even nuclei, the enhancement of the level density is observed already at the transition point. The collective phase is reached when the single-particle transfer matrix elements are dominant in the shell model Hamiltonian, providing a sign of their fundamental role.
Signatures of shell evolution in alpha decay across the N = 126 shell closure
Rui-Wang; Wang, Rui-Yao; Qian, Yi-Bin; Ren, Zhong-Zhou
2017-06-01
Within the alpha-cluster model, we particularly investigate the alpha decay of exotic nuclei in the vicinity of the N = 126 neutron shell plus the Z = 82 proton shell. The systematics of alpha-preformation probability (P α ), as an indicator of the shell effect, is deduced from the ratio of the experimental decay width to the calculated one. Through the comparative analysis of the P α trend in the N = 124-130 isotonic chain, the N = 126 and Z = 82 shell closures are believed to strongly affect the formation of the alpha particle before its penetration. Additionally, the P α variety in Po and Rn isotopes is presented as another proof for such an influence. More importantly, it may be concluded that the expected neutron (or proton) shell effect gradually fades away along with the increasing valence proton (or neutron) number. The odd-even staggering presented in the P α value is also discussed. Supported by National Natural Science Foundation of China (11375086, 11535004, 11605089, 11120101005), Natural Science Youth Fund of Jiangsu Province (BK20150762), Fundamental Research Funds for the Central Universities (30916011339), 973 National Major State Basic Research and Development Program of China (2013CB834400), and a Project Funded by the Priority Academic Programme Development of JiangSu Higher Education Institutions (PAPD)
International Nuclear Information System (INIS)
Dote, Akinobu; Akaishi, Yoshinori; Yamazaki, Toshimitsu
2005-01-01
New nuclei 'K-bar-Mesic Nuclei' having the strangeness are described. At first it is shown that the strongly attractive nature of K-bar N interaction is reasoned inductively from consideration of the relation between Kaonic hydrogen atom and Λ (1405) which is an excited state of hyperon Λ. The K-bar N interactions are reviewed and summarized into three categories: 1. Phenomenological approach with density dependent K-bar N interaction (DD), relativistic mean field (RMF) approach, and hybrid of them (RMF+DD). 2. Boson exchange model. 3. Chiral SU(3) theory. The investigation of some light K-bar-nuclei by Akaishi and Yamazaki using phenomenological K-bar N interaction is explained in detail. Studies by antisymmetrized molecular dynamics (AMD) approach are also presented. From these theoretical researches, the following feature of K-bar-mesic nuclei are revealed: 1) Ground state is discrete and bound by 100 MeV or more. 2) Density is very high in side the K-bar-mesic nuclei. 3) Strange structures develop which are not seen in ordinary nuclei. Finally some recent experiments to explore K-bar-mesic nuclei are reviewed. (S. Funahashi)
Structure and symmetries of odd-odd triaxial nuclei
Energy Technology Data Exchange (ETDEWEB)
Palit, R. [Tata Institute of Fundamental Research, Department of Nuclear and Atomic Physics, Colaba, Mumbai (India); Bhat, G.H. [University of Kashmir, Department of Physics, Srinagar (India); Govt. Degree College Kulgam, Department of Physics, Kulgam (India); Sheikh, J.A. [University of Kashmir, Department of Physics, Srinagar (India); Cluster University of Srinagar, Srinagar, Jammu and Kashmir (India)
2017-05-15
Rotational spectra of odd-odd Rh and Ag isotopes are investigated with the primary motivation to search for the spontaneous chiral symmetry breaking phenomenon in these nuclei. The experimental results obtained on the degenerate dipole bands of some of these isotopes using a large array of gamma detectors are discussed and studied using the triaxial projected shell (TPSM) approach. It is shown that, first of all, to reproduce the odd-even staggering of the known yrast bands of these nuclei, large triaxial deformation is needed. This large triaxial deformation also gives rise to doublet band structures in many of these studied nuclei. The observed doublet bands in these isotopes are shown to be reproduced reasonably well by the TPSM calculations. Further, the TPSM calculations for neutron-rich nuclei indicate that the ideal manifestation of the chirality can be realised in {sup 106}Rh and {sup 112}Ag, where the doublet bands have similar electromagnetic properties along with small differences in excitation energies. (orig.)
Heavy ions as probes of nuclei far from stability
International Nuclear Information System (INIS)
Moltz, D.M.; Nitschke, J.M.; Wilmarth, P.A.; Toth, K.S.
1989-01-01
Nuclei located far from stability provide us with an opportunity for studying nuclear matter existing under unusual conditions. In these regions of instability, radioactive decay becomes the predominant technique by which one can obtain structure information. We have been involved in the investigation of nuclear properties of nuclei close to the proton drip line. In our explorations we have utilized heavy-ion fusion, followed by particle evaporation, to produce the extremely neutron-deficient nuclei of interest. In our studies, single-particle states near the 82-neutron shell, populated in the β decay of short-lived nuclides, have been examined and their excitation energies determined. Numerous new isotopes, isomers, and β-delayed-proton and α-particle emitters have been discovered. This contribution will discuss our particle-decay investigations. These decay modes provide us with a convenient means of discovering new isotopes whose identification opens the way for further, more extensive explorations. Also, particle-decay energies in many instances can be used to determine mass differences between parent and daughter ground states. Such measurements are therefore used to test mass formulae and to obtain estimates of masses for proton rich nuclei. 19 refs., 13 figs
Atomic nuclei decay modes by spontaneous emission of heavy ions
International Nuclear Information System (INIS)
Poenaru, D.N.; Ivascu, M.; Sandulescu, A.
1984-01-01
The great majority of the known nuclei, including the so-called stable nuclides, are in fact metastable with respect to several modes of spontaneous superasymmetric splitting. If the lifetime against these processes is larger than 10 30 s, the phenomenon is not detectable with available experimental techniques, hence one can admit stability from the practical point of view. A model extended from the fission theory of alpha decay allows one to estimate the lifetimes and the branching ratios relatively to the alpha decay for these natural radioactivities. From a huge amount of systematical calculations it is concluded that the process should proceed with maximum intensity in the trans-lead nuclei, where the minimum lifetime is obtained for parent nuclei - heavy clusters leading to a magic ( 208 Pb) or almost daughter nucleus. More than 140 nuclides with atomic number smaller than 25 are possible candidates to be emitted from heavy nuclei, with half-life n the 10 10 -10 30 s range. The shell structure and pairing effects are clearly manifested in these new decay modes
Microscopical description of isovector collective Osup(+) states in atomic nuclei
International Nuclear Information System (INIS)
Chekanov, N.A.
1983-01-01
A microscopical consistent description of isobar-analogue states and isovector monopole giant resonances is given in framework of the random-phase theory. The necessary one-particle basis, including the continuous spectrum, is determined by solution of the Hartree-Fock equations with the effective Skyrme-type interaction. An important feature of such a description is an automatical fulfilment of the consistency conditions relating the shell potential, nuclear density and the residual interaction. Effects due to Coulomb interaction in nuclei are investigated, such as the Coulomb shift energies, isospin admixtures to the ground state of the parent nucleus. Transition densities for the analogue states are obtained. Numerical calculations have been performed in the coordinate space for a number of neutron-rich nuclei
An Exactly Solvable Supersymmetric Model of Semimagic Nuclei
International Nuclear Information System (INIS)
Balantekin, A. B.; Gueven, Nurtac; Pehlivan, Yamac
2008-01-01
A simple model of nucleons coupled to angular momentum zero (s-pairs) occupying the valance shell of a semi-magic nuclei is considered. The model has a separable, orbit dependent pairing interaction which dominates over the kinetic term. It is shown that such an interaction leads to an exactly solvable model whose (0 + ) eigenstates and energies can be computed very easily with the help of the algebraic Bethe ansatz method. It is also shown that the model has a supersymmetry which connects the spectra of some semimagic nuclei. The results obtained from this model for the semimagic Ni isotopes from 58 Ni to 68 Ni are given. In addition, a new and easier technique for calculating the energy eigenvalues from the Bethe ansatz equations is also presented.
Monopole transitions in hot nuclei
International Nuclear Information System (INIS)
Sujkowski, Z.
1994-01-01
Monopole transitions can be a signature of shape changing in a hot, pulsating nucleus (the low energy E0 mode) and/or a measure of the compressibility of finite nuclei (GMR, the breathing mode). Experimental information pertaining to GMR is reviewed. Recipes for deducing the incompressibility modules for infinite nuclear matter from data on GMR are discussed. Astrophysical implications are outlined. The first attempts at locating the GMR strength in moderately hot nuclei are described. Prospects for improving the experimental techniques to make an observation of this strength in selected nuclei unambiguous are discussed. (author). 46 refs, 8 figs
Monopole transitions in hot nuclei
Energy Technology Data Exchange (ETDEWEB)
Sujkowski, Z. [Soltan Inst. for Nuclear Studies, Otwock-Swierk (Poland)
1994-12-31
Monopole transitions can be a signature of shape changing in a hot, pulsating nucleus (the low energy E0 mode) and/or a measure of the compressibility of finite nuclei (GMR, the breathing mode). Experimental information pertaining to GMR is reviewed. Recipes for deducing the incompressibility modules for infinite nuclear matter from data on GMR are discussed. Astrophysical implications are outlined. The first attempts at locating the GMR strength in moderately hot nuclei are described. Prospects for improving the experimental techniques to make an observation of this strength in selected nuclei unambiguous are discussed. (author). 46 refs, 8 figs.
Electron scattering for exotic nuclei
International Nuclear Information System (INIS)
Suda, T.
2013-01-01
An electron scattering facility is under construction in RIKEN RI Beam Factory, Japan, which is dedicated to the structure studies of short-lived nuclei. This is the world's first and currently only facility of its type. The construction is nearly completed, and the first electron scattering experiment off short-lived nuclei will be carried out in the beginning of next year. The charge density distributions of short-lived nuclei will be precisely determined by elastic electron scattering for the first time. Physics pursued at this facility including future perspectives are explained
Cavitation inception from bubble nuclei
DEFF Research Database (Denmark)
Mørch, Knud Aage
2015-01-01
, and experimental investigations of bubbles and cavitation inception have been presented. These results suggest that cavitation nuclei in equilibrium are gaseous voids in the water, stabilized by a skin which allows diffusion balance between gas inside the void and gas in solution in the surrounding liquid....... The cavitation nuclei may be free gas bubbles in the bulk of water, or interfacial gaseous voids located on the surface of particles in the water, or on bounding walls. The tensile strength of these nuclei depends not only on the water quality but also on the pressure-time history of the water. A recent model...
International Nuclear Information System (INIS)
Ayala, A.L.
1996-01-01
In this talk we present our detailed study (theory and numbers) on the shadowing corrections to the gluon structure functions for nuclei. Starting from rather controversial information on the nucleon structure function which is originated by the recent HERA data, we develop the Glauber approach for the gluon density in a nucleus based on Mueller formula and estimate the value of the shadowing corrections in this case. Then we calculate the first corrections to the Glauber approach and show that these corrections are big. Based on this practical observation we suggest the new evolution equation which takes into account the shadowing corrections and solve it. We hope to convince you that the new evolution equation gives a good theoretical tool to treat the shadowing corrections for the gluons density in a nucleus and, therefore, it is able to provide the theoretically reliable initial conditions for the time evolution of the nucleus-nucleus cascade. The initial conditions should be fixed both theoretically and phenomenologically before to attack such complicated problems as the mixture of hard and soft processes in nucleus-nucleus interactions at high energy or the theoretically reliable approach to hadron or/and parton cascades for high energy nucleus-nucleus interaction. 35 refs., 24 figs., 1 tab
Jolie, J
2002-01-01
All the elementary particles that make up matter (as do quarks, electrons, neutrinos....) are fermions, the particles that convey the fundamental interactions (as do photons, gluons, W, Z...) are bosons. Composite particles are either bosons, or fermions according to the number of fermions they contain: if this number is even the particle is a boson, otherwise it is a fermion. According to this rule a proton is a fermion and the He sup 4 atom is a boson. Symmetry plays an important role in the standard model, a symmetry is a transformation that connect bosons with other bosons or fermions with other fermions. Supersymmetry associates a boson with a fermion or a fermion with a boson, in fact supersymmetry connects nuclei that are not generally considered as akin. Supersymmetry has just been observed in low energy levels of Gold sup 1 sup 9 sup 5 sup - sup 1 sup 9 sup 6 and Platinum sup 1 sup 9 sup 4 - sup 1 sup 9 sup 5 , it means that the description of these energy levels is simplified and can be made by a co...
International Nuclear Information System (INIS)
Jolie, J.
2002-01-01
All the elementary particles that make up matter (as do quarks, electrons, neutrinos....) are fermions, the particles that convey the fundamental interactions (as do photons, gluons, W, Z...) are bosons. Composite particles are either bosons, or fermions according to the number of fermions they contain: if this number is even the particle is a boson, otherwise it is a fermion. According to this rule a proton is a fermion and the He 4 atom is a boson. Symmetry plays an important role in the standard model, a symmetry is a transformation that connect bosons with other bosons or fermions with other fermions. Supersymmetry associates a boson with a fermion or a fermion with a boson, in fact supersymmetry connects nuclei that are not generally considered as akin. Supersymmetry has just been observed in low energy levels of Gold 195-196 and Platinum 194 - 195 , it means that the description of these energy levels is simplified and can be made by a common set of quantum numbers. (A.C.)
Photon interactions with nuclei
International Nuclear Information System (INIS)
Thornton, S.T.; Sealock, R.M.
1989-01-01
This document is a progress report for DOE Grant No. FG05-89ER40501, A000. The grant began March, 1989. Our primary research effort has been expended at the LEGS project at Brookhaven National Laboratory. This report will summarize our present research effort at LEGS as well as data analysis and publications from previous experiments performed at SLAC. In addition the principal investigators are heavily involved in the CLAS collaboration in Hall B at CEBAF. We have submitted several letters of intent and proposals and have made commitments to construct experimental equipment for CEBAF. We expect our primary experimental effort to continue at LEGS until CEBAF becomes operational. This report will be divided into separate sections describing our progress at LEGS, SLAC, and CEBAF. We will also discuss our significant efforts in the education and training of both undergraduate and graduate students. Photon detectors are described as well as experiments on delta deformation in nuclei of quasielastic scattering and excitation of the delta by 4 He(e,e')
International Nuclear Information System (INIS)
Robertson, R.G.H.
1980-01-01
A summary of parity violating effects in nuclei is given. Thanks to vigorous experimental and theoretical effort, it now appears that a reasonably well-defined value for the weak isovector π-nucleon coupling constant can be obtained. There is one major uncertainty in the analysis, namely the M2/E1 mixing ratio for the 2.79 MeV transition in 21 Ne. This quantity is virtually impossible to calculate reliably and must be measured. If it turns out to be much larger than 1, then a null result in 21 Ne is expected no matter what the weak interaction, so an experimental determination is urgently needed. The most promising approach is perhaps a measurement of the pair internal conversion coefficient. Of course, a direct measurement of a pure isovector case is highly desirable, and it is to be hoped that the four ΔT = 1 experiments will be pushed still further, and that improved calculations will be made for the 6 Li case. Nuclear parity violation seems to be rapidly approaching an interesting and useful synthesis
International Nuclear Information System (INIS)
Arima, A.
2003-01-01
(1) There are symmetries in nature, and the concept of symmetry has been used in art and architecture. The symmetry is evaluated high in the European culture. In China, the symmetry is broken in the paintings but it is valued in the architecture. In Japan, however, the symmetry has been broken everywhere. The serious and interesting question is why these differences happens? (2) In this lecture, I reviewed from the very beginning the importance of the rotational symmetry in quantum mechanics. I am sorry to be too fundamental for specialists of nuclear physics. But for people who do not use these theories, I think that you could understand the mathematical aspects of quantum mechanics and the relation between the angular momentum and the rotational symmetry. (3) To the specialists of nuclear physics, I talked about my idea as follows: dynamical treatment of collective motions in nuclei by IBM, especially the meaning of the degeneracy observed in the rotation bands top of γ vibration and β vibration, and the origin of pseudo-spin symmetry. Namely, if there is a symmetry, a degeneracy occurs. Conversely, if there is a degeneracy, there must be a symmetry. I discussed some details of the observed evidence and this correspondence is my strong belief in physics. (author)
Collective excitations in nuclei
International Nuclear Information System (INIS)
Chomaz, Ph.
1997-01-01
The properties of the nucleus cannot be reduced to the properties of its constituents: it is a complex system. The fact that many properties of the nucleus are consequences of the existence of mean-field potential is a manifestation of this complexity. In particular the nucleons can thus self-organize in collective motions such as giant resonances. Therefore the study of these collective motions is a very good to understand the properties of the nucleus itself. The purpose of this article was to stress some aspects of these collective vibrations. In particular we have studied how an ensemble of fermions as the nucleus can self-organize in collective vibrations which are behaving like a gas of bosons in weak interaction. The understanding of these phenomena remains one of the important subjects of actually in the context of quantal systems in strong interaction. In particular the study of the states with one or two vibration quanta provides a direct information on the structure if nuclei close to their ground states. (author)
Collective excitations in nuclei
Energy Technology Data Exchange (ETDEWEB)
Chomaz, Ph
1997-12-31
The properties of the nucleus cannot be reduced to the properties of its constituents: it is a complex system. The fact that many properties of the nucleus are consequences of the existence of mean-field potential is a manifestation of this complexity. In particular the nucleons can thus self-organize in collective motions such as giant resonances. Therefore the study of these collective motions is a very good to understand the properties of the nucleus itself. The purpose of this article was to stress some aspects of these collective vibrations. In particular we have studied how an ensemble of fermions as the nucleus can self-organize in collective vibrations which are behaving like a gas of bosons in weak interaction. The understanding of these phenomena remains one of the important subjects of actually in the context of quantal systems in strong interaction. In particular the study of the states with one or two vibration quanta provides a direct information on the structure if nuclei close to their ground states. (author) 270 refs.
A nucleon-pair and boson coexistent description of nuclei
Dai, Lianrong; Pan, Feng; Draayer, J. P.
2017-07-01
We study a mixture of s-bosons and like-nucleon pairs with the standard pairing interaction outside an inert core. Competition between the nucleon-pairs and s-bosons is investigated in this scenario. The robustness of the BCS-BEC coexistence and crossover phenomena are examined through an analysis of pf-shell nuclei with realistic single-particle energies, in which two configurations with Pauli blocking of nucleon-pair orbits due to the formation of the s-bosons is taken into account. When the nucleon-pair orbits are considered to be independent of the s-bosons, the BCS-BEC crossover becomes smooth, with the number of the s-bosons noticeably more than that of the nucleon-pairs near the half-shell point, a feature that is demonstrated in the pf-shell for several values of the standard pairing interaction strength. As a further test of the robustness of the BCS-BEC coexistence and crossover phenomena in nuclei, results are given for values of even-even 102-130Sn with 100Sn taken as a core and valence neutron pairs confined within the 1d 5/2, 0g 7/2, 1d 3/2, 2s 1/2, 1h 11/2 orbits in the nucleon-pair orbit and the s-boson independent approximation. The results indicate that the B(E2) values are reproduced well. Supported by National Natural Science Foundation of China (11375080, 11675071), the U.S. National Science Foundation (OCI-0904874 and ACI-1516338), U. S. Department of Energy (DE-SC0005248), the Southeastern Universities Research Association, the China-U. S. Theory Institute for Physics with Exotic Nuclei (CUSTIPEN) (DE-SC0009971), and the LSU-LNNU joint research program (9961) is acknowledged
Testing refined shell-model interactions in the sd shell: Coulomb excitation of Na26
Siebeck, B; Blazhev, A; Reiter, P; Altenkirch, R; Bauer, C; Butler, P A; De Witte, H; Elseviers, J; Gaffney, L P; Hess, H; Huyse, M; Kröll, T; Lutter, R; Pakarinen, J; Pietralla, N; Radeck, F; Scheck, M; Schneiders, D; Sotty, C; Van Duppen, P; Vermeulen, M; Voulot, D; Warr, N; Wenander, F
2015-01-01
Background: Shell-model calculations crucially depend on the residual interaction used to approximate the nucleon-nucleon interaction. Recent improvements to the empirical universal sd interaction (USD) describing nuclei within the sd shell yielded two new interactions—USDA and USDB—causing changes in the theoretical description of these nuclei. Purpose: Transition matrix elements between excited states provide an excellent probe to examine the underlying shell structure. These observables provide a stringent test for the newly derived interactions. The nucleus Na26 with 7 valence neutrons and 3 valence protons outside the doubly-magic 16O core is used as a test case. Method: A radioactive beam experiment with Na26 (T1/2=1,07s) was performed at the REX-ISOLDE facility (CERN) using Coulomb excitation at safe energies below the Coulomb barrier. Scattered particles were detected with an annular Si detector in coincidence with γ rays observed by the segmented MINIBALL array. Coulomb excitation cross sections...
International Nuclear Information System (INIS)
Kleymann, G.
1976-01-01
This paper is a compilation of results of experimental and theoretical studies on the term diagrams of odd-even nuclei from the isotope series of Nb, Tc, Rh and Ag, published until October 1975. As a relatively simple interpretation of the excitements of these nuclei, De Shalit proposed the coupling of a particle, whose quantum numbers may be derived from a shell model, to excited states of the core of the nucleus. (orig./BJ) [de
Shell model test of the Porter-Thomas distribution
International Nuclear Information System (INIS)
Grimes, S.M.; Bloom, S.D.
1981-01-01
Eigenvectors have been calculated for the A=18, 19, 20, 21, and 26 nuclei in an sd shell basis. The decomposition of these states into their shell model components shows, in agreement with other recent work, that this distribution is not a single Gaussian. We find that the largest amplitudes are distributed approximately in a Gaussian fashion. Thus, many experimental measurements should be consistent with the Porter-Thomas predictions. We argue that the non-Gaussian form of the complete distribution can be simply related to the structure of the Hamiltonian
Delayed neutron emission near the shell-closures
Directory of Open Access Journals (Sweden)
Borzov Ivan
2016-01-01
Full Text Available The self-consistent Density Functional + Continuum QRPA approach (DF+CQRPA provides a good description of the recent experimental beta-decay half-lives and delayed neutron emission branchings for the nuclei approaching to (and beyond the neutron closed shells N = 28; 50; 82. Predictions of beta-decay properties are more reliable than the ones of standard global approaches traditionally used for the r-process modelling. An impact of the quasi-particle phonon coupling on the delayed multi-neutron emission rates P2n, P3n,… near the closed shells is also discussed.
Extended microscopic theory for N ∼ Z nuclei
International Nuclear Information System (INIS)
Drumev, K.P.; Georgieva, A.I.
2015-01-01
A symmetry adapted realization of the Pairing-plus-Quadrupole Model /PQM/ has been explored in the framework of the Elliott's SU(3) Model. The aim is to obtain the complementary and competing features of the pairing and quadrupole interactions in the model Hamiltonian, containing both of them as limiting cases of dynamical symmetries. For the purpose, one or two control parameters are introduced which account for the relative importance of each term in the Hamiltonian and serve to describe the effect of phase transition. The calculations are performed for nuclei in a single oscillator shell
Estimates of production and structure of nuclei with Z = 119
Adamian, G. G.; Antonenko, N. V.; Lenske, H.
2018-02-01
The comparative analysis of the hot fusion reactions 50Ti +247-249Bk and 51V +246-248Cm for synthesis of element 119 is made with the dinuclear system model and the prediction of nuclear properties of the microscopic-macroscopic approach, where the closed proton shell at Z ≥ 120 is expected. The quasiparticle structures of nuclei in the α-decay chain of 295119 and a possible spread of alpha energies are studied. The calculated values of Qα are compared with available experimental data. The termination of the α-decay chain of 295119 is revealed.
Single proton transfer reactions on odd-even nuclei
International Nuclear Information System (INIS)
Blasi, N.
1984-01-01
This thesis is devoted to the study of one proton transfer reactions, performed with the use of the magnetic spectrograph QMG/2 of the KVI, in two regions of the mass table. Stripping and pickup reactions on the odd-A target nuclei 193 Ir and 197 Au are described in the first part. The experimental spectroscopic factors obtained are used to test several collective models that are based on coupling between bosons (phonons) and fermions. In the second part, the proton stripping reactions on 113 In and 115 In are studied. Shell model calculations are performed and applied to the experimental results. (Auth.)
Very proton-rich nuclei with N asymptotically equals 82
International Nuclear Information System (INIS)
Nolte, E.
1984-01-01
The proton-rich nuclei with N asymptotically equals 82 show beautifully properties, which are perfectly described by the nuclear shell model. Some of these properties are the occurrence of seniority isomerism in the proton-rich N=82 isotones and the perfect description of the corresponding life times by the seniority scheme as well as the observation of favoured Gamow-Teller β transitions in this nuclear region and the dependence of the corresponding ft values on the number of the envolved nucleons. (author)
Gamow-Teller beta decay of proton-rich nuclei
International Nuclear Information System (INIS)
Klepper, O.; Rykaczewski, K.
1990-11-01
The beta decays of 48 Mn and of even-even nuclei near the double shell-closures at 100 Sn and 146 Gd are currently investigated at the GSI on-line mass separator. Their Gamow-Teller strength are surveyed in their present experimental status, together with related results from the ISOLDE (CERN) and ISOCELE (Orsay) separators, and are compared with predictions from different nuclear models. The strength of the 0 + → 1 + Gamow-Teller transitions is compiled in tables and graphs. (orig.)
Fission mass yields of excited medium heavy nuclei
International Nuclear Information System (INIS)
Sandulescu, A.; Depta, K.; Herrmann, R.; Greiner, W.; Scheid, W.
1985-01-01
The mass distributions resulting from the fission of excited medium mass nuclei are discussed on the basis of the fragmentation theory. It is shown that very asymmetric fission events can be expected with rates which are only a few orders of magnitude smaller than the rates for symmetric fission. As an example a calculation of the fission mass distribution of the excited 172 Yb compound nucleus is presented. This mass distribution reveals observable structures over the entire range of the mass asymmetry due to valleys in the potential energy surface for fission fragments with closed proton and neutron shells
Energy Technology Data Exchange (ETDEWEB)
1978-01-01
This paper notes the necessity of developing an international coal trade on a very large scale. The role of Shell in the coal industry is examined; the regions in which Shell companies are most active are Australia, Southern Africa, Indonesia; Europe and North America. Research is being carried out on marketing and transportation, especially via slurry pipelines; coal-oil emulsions; briquets; fluidized-bed combustion; recovery of coal from potential waste material; upgrading of low-rank coals; unconventional forms of mining; coal conversion (the Shell/Koppers high-pressure coal gasification process). Techniques for cleaning flue gas (the Shell Flue Gas Desulfurization process) are being examined.
Altenbach, Holm
2011-01-01
In this volume, scientists and researchers from industry discuss the new trends in simulation and computing shell-like structures. The focus is put on the following problems: new theories (based on two-dimensional field equations but describing non-classical effects), new constitutive equations (for materials like sandwiches, foams, etc. and which can be combined with the two-dimensional shell equations), complex structures (folded, branching and/or self intersecting shell structures, etc.) and shell-like structures on different scales (for example: nano-tubes) or very thin structures (similar
Nuclear spectroscopy in nuclei with Z ≥ 110
Energy Technology Data Exchange (ETDEWEB)
Ackermann, D., E-mail: D.Ackermann@gsi.de
2015-12-15
The nuclear structure of species at the extreme of highest atomic numbers Z and nuclear masses A promises to reveal intriguing new features of this exotic hadronic matter. Their stability itself they owe to quantum-mechanic effects only. They form metastable states which, governed by the subtle interplay of α decay and spontaneous fission versus quantum-mechanic stabilization via shell effects, are in some cases more robust against disintegration than their ground states. Following the isotopic and isotonic trends of single particle levels, as well as collective features like deformation, may reveal the path towards the gap in the level densities, expected for the next closed proton and neutron shells at the so-called “island of stability” of spherical superheavy nuclei. Their atomic configuration offers via X-ray spectroscopy a tool to identify the atomic number of heavy species, where other more traditional methods like evaporation residue (ER)–α correlation are not applicable.
Systematic study of α half-lives of superheavy nuclei
Budaca, A. I.; Silisteanu, I.
2014-03-01
Two different descriptions of the α-decay process, namely, the shell model rate theory and phenomenological description are emphasized to investigate the α-decay properties of SHN. These descriptions are shortly presented and illustrated by their results. Special attention is given to the shell structure and resonance scattering effects due to which they exist and decay. A first systematics of α-decay properties of SHN was performed by studying the half-life vs. energy correlations in terms of atomic number and mass number. Such a systematics shows that the transitions between even-even nuclei are favored, while all other transitions with odd nucleons are prohibited. The accuracy of experimental and calculated α-half-lives is illustrated by the systematics of these results.
Ground-state properties of neutron magic nuclei
Energy Technology Data Exchange (ETDEWEB)
Saxena, G., E-mail: gauravphy@gmail.com [Govt. Women Engineering College, Department of Physics (India); Kaushik, M. [Shankara Institute of Technology, Department of Physics (India)
2017-03-15
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 plus Bardeen–Cooper–Schrieffer 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 nonrelativistic 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.
Dynamic polarization of radioactive nuclei
International Nuclear Information System (INIS)
Kiselev, Yu.F.; Lyuboshits, V.L.; )
2001-01-01
Radioactive nuclei, embedded into a frozen polarized proton target, atr proposed to polarize by means of some dynamic polarization methods. Angular distributions of γ-quanta emitted ny 22 Na(3 + ) in the cascade β-γ-radiation are calculated. It is shown that this distribution does not depend on the spin temperature sing at the Boltzmann distribution of populations among the Zeeman magnetic substates, whereas the tensor polarization of quadrupole nuclei, placed in the electric field of the crystal, causes the considerable sing dependence. The new method promises wide opportunities for the magnetic structure investigations as well as for the study of spin-spin interaction dynamics of rare nuclei in dielectrics. Physical-technical advantages and disadvantages of the given method are discussed for the polarization of heavy nuclei in the on-line implantation mode [ru
The delta in nuclei. Experiments
International Nuclear Information System (INIS)
Roy-Stephan, M.
1989-01-01
Experimental aspects of the Δ excitation will be presented. The Δ excitation in nuclei will be compared to the free Δ excitation. Various probes will be reviewed and their specific features will be underlined [fr