WorldWideScience

Sample records for medium-mass neutron-rich nuclei

  1. Neutron rich nuclei

    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

  2. Structure of neutron-rich nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Nazarewicz, W. [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Physics]|[Oak Ridge National Lab., TN (United States). Physics Div.]|[Warsaw Univ. (Poland). Inst. of Theoretical Physics

    1997-11-01

    One of the frontiers of today`s nuclear science is the ``journey to the limits``: of atomic charge and nuclear mass, of neutron-to-proton ratio, and of angular momentum. The new data on exotic nuclei are expected to bring qualitatively new information about the fundamental properties of the nucleonic many-body system, the nature of the nuclear interaction, and nucleonic correlations at various energy-distance scales. In this talk, current developments in nuclear structure of neutron-rich nuclei are discussed from a theoretical perspective.

  3. Structure of neutron-rich nuclei

    International Nuclear Information System (INIS)

    Nazarewicz, W.; Oak Ridge National Lab., TN; Warsaw Univ.

    1997-11-01

    One of the frontiers of today's nuclear science is the ''journey to the limits'': of atomic charge and nuclear mass, of neutron-to-proton ratio, and of angular momentum. The new data on exotic nuclei are expected to bring qualitatively new information about the fundamental properties of the nucleonic many-body system, the nature of the nuclear interaction, and nucleonic correlations at various energy-distance scales. In this talk, current developments in nuclear structure of neutron-rich nuclei are discussed from a theoretical perspective

  4. Modeling a neutron rich nuclei source

    International Nuclear Information System (INIS)

    Mirea, M.; Bajeat, O.; Clapier, F.; Ibrahim, F.; Mueller, A.C.; Pauwels, N.; Proust, J.; Mirea, M.

    2000-01-01

    The deuteron break-up process in a suitable converter gives rise to intense neutron beams. A source of neutron rich nuclei based on the neutron induced fission can be realised using these beams. A theoretical optimization of such a facility as a function of the incident deuteron energy is reported. The model used to determine the fission products takes into account the excitation energy of the target nucleus and the evaporation of prompt neutrons. Results are presented in connection with a converter-target specific geometry. (authors)

  5. Calculation of the radii of neutron rich light exotic nuclei

    International Nuclear Information System (INIS)

    Charagi, S.K.; Gupta, S.K.

    1991-01-01

    The interaction cross section of a few unstable neutron rich nuclei have been measured using exotic isotope beams produced through the projectile fragmentation process in high energy heavy-ion collisions. Interaction cross section of He, Li, Be and B isotope projectiles with Be, C and Al targets have thus been measured at 790 MeV/nucleon. We have made a comprehensive analysis of the data on the interaction cross section, to extract the radii of these neutron rich light nuclei. 7 refs., 1 fig., 3 tabs

  6. Structure of neutron-rich nuclei

    International Nuclear Information System (INIS)

    Nazarewicz, W.; Ploszajczak, M.

    2003-01-01

    Structure of exotic radioactive nuclei having extreme neutron-to-proton ratios is different from that around the stability line. This short review discusses the progress in modeling of exotic nuclei in the nuclear ''Terra Incognita''. The consistent theoretical description of weakly bound systems requires a synergy between nuclear structure and nuclear reaction methods. (orig.)

  7. Structure of light neutron-rich nuclei through Coulomb dissociation

    Indian Academy of Sciences (India)

    Home; Journals; Pramana – Journal of Physics; Volume 57; Issue 2-3. Structure of light neutron-rich nuclei through Coulomb dissociation. U Datta Pramanik T Aumann D Cortina H Emling H Geissel M Hellström R Holzmann N Iwasa Y Leifels G Münzenberg M Rejmund C Scheidenberger K Sümmerer A Leistenschneider ...

  8. Maris polarization in neutron-rich nuclei

    Science.gov (United States)

    Shubhchintak; Bertulani, C. A.; Aumann, T.

    2018-03-01

    We present a theoretical study of the Maris polarization effect and its application in quasi-free reactions to assess information on the structure of exotic nuclei. In particular, we explore the dependence of the polarization effect on neutron excess and neutron-skin thickness. We discuss the uncertainties in the calculations of triple differential cross sections and of analyzing powers due the choices of various nucleon-nucleon interactions and optical potentials and the limitations of the method. Our study implies that polarization variables in (p, 2p) reactions in inverse kinematics can be an effective probe of single-particle structure of nuclei in radioactive-beam facilities.

  9. 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.)

  10. 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.)

  11. Direct versus sequential fragmentation of neutron rich nuclei

    International Nuclear Information System (INIS)

    Bertulani, C.A.; Hussein, M.S.

    1989-11-01

    The dissociation of neutron rich nuclei from secondary beams incident on several targets can be explained within two distinct models: a) the weakly bound neutrons form clusters near the nuclear surface, and, b) all protons can vibrate against all neutrons in a soft mode. We show that the momentum widths of the projectile fragments, as well as the total cross sections for the dissociation, is consistent with both hypothesis. The presently available data do not unambiguously distinguish between the two models. (author) [pt

  12. 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

  13. New proton and neutron magic numbers in neutron rich nuclei

    OpenAIRE

    Abbas, Afsar

    2003-01-01

    It is now known that in neutron rich nuclei, old magic numbers disappear and new ones appear. Single nucleon and double nucleon separation energies are plotted here in all possible manner.Using this data it is shown here for the first time that nuclei with pair of proton number Z and neutron number N (Z,N) : (6,12), (8,16), (10,20), (11,22) and (12,24) exhibit exceptional stability or magicity. As such these magic numbers appear in pairs. This correlation is shown here to be indicative of pre...

  14. Multifragmentation Fission in Neutron-rich Uranium and Thorium Nuclei

    Directory of Open Access Journals (Sweden)

    R. N. Panda

    2012-09-01

    Full Text Available The structural properties of the recently predicted thermally fissile neutron-rich Uranium and Thorium isotopes are studied using the relativistic mean field formalism. The investigation of the new phenomena of multifragmentation fission is analyzed. In addition to the fission properties, the total nuclear reaction cross section which is a measure of the probability of production of these nuclei is evaluated taking 6,11Li and 16,24O as projectiles. The possible use of nuclear fuel in an accelerator based reactor is discussed which may be the substitution of 233,235U and 239Pu for nuclear fuel in near future.

  15. The pygmy dipole resonance in neutron-rich nuclei

    International Nuclear Information System (INIS)

    Hung, Nguyen Quang; Kiet, Hoang Anh Tuan; Duc, Huynh Ngoc; Chuong, Nguyen Thi

    2016-01-01

    The pygmy dipole resonance (PDR), which has been observed via the enhancement of the electric dipole strength E 1 of atomic nuclei, is studied within a microscopic collective model. The latter employs the Hartree-Fock (HF) method with effective nucleon-nucleon interactions of the Skyrme types plus the random-phase approximation (RPA). The results of the calculations obtained for various even-even nuclei such as 16-28 O, 40-58 Ca, 100-120 Sn, and 182-218 Pb show that the PDR is significantly enhanced when the number of neutrons outside the stable core of the nucleus is increased, that is, in the neutron-rich nuclei. As the result, the relative ratio between the energy weighted sum of the strength of the PDR and that of the GDR (giant dipole resonance) does not exceed 4%. The collectivity of the PDR and GDR states will be also discussed. (paper)

  16. Properties of neutron-rich nuclei studied by fission product nuclear chemistry

    International Nuclear Information System (INIS)

    Meyer, R.A.; Henry, E.A.; Griffin, H.C.; Lien, O.G. III; Lane, S.M.; Stevenson, P.C.; Yaffe, R.P.; Skarnemark, G.

    1979-09-01

    A review is given of the properties of neutron-rich nuclei studied by fission product nuclear chemistry and includes the techniques used in elemental isolation and current research on the structure of nuclei near 132 Sn, particle emission, and coexisting structure in both neutron-poor and neutron-rich nuclei. 35 references

  17. Structure of light neutron-rich nuclei through Coulomb dissociation

    Indian Academy of Sciences (India)

    O, the low-lying E1 strength amounts up to about 12% of the energy weighted dipole sum rule strength depending on neutron excess. The cluster sum rule limit with. ½. O as a core is almost exhausted for. ½,½. O, while for more neutron rich isotopes the strength with respect to that limit decreases. Keywords. Coulomb ...

  18. 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.)

  19. Spontaneous fission of neutron-rich superheavy nuclei

    International Nuclear Information System (INIS)

    Gherghiescu, R.A.

    1997-01-01

    Neutron-rich isotopes of the superheavy elements 112, 114, and 116 have been studied for neutron numbers 184, 186, and 188. The spontaneous fission life-time calculations have been performed within the WKB method. Large values have been obtained due to the proton-shell closure 114. The maximum of the fission lifetime occurs for the double-magic superheavy nucleus (114,184). (author)

  20. Study of very neutron-rich nuclei produced by means of a 48Ca beam

    International Nuclear Information System (INIS)

    Lewitowicz, M.; Artukh, A.G.

    1991-01-01

    The results of experiments with a 48 Ca beam performed at GANIL are presented and discussed. More than 30 very neutron-rich isotopes were identified or studied for the first time. The evidence for particle-unstable character of the 26 O isotope is reported. Half-life measurements for light neutron rich nuclei are compared with different theoretical predictions. (author) 14 refs.; 6 figs.; 1 tab

  1. Structure of light neutron-rich nuclei through Coulomb dissociation

    Indian Academy of Sciences (India)

    The physics of exotic nuclei has attracted much interest during the past decade. The prop- erties of nuclei with large neutron excess have turned out to be very different compared to those of stable nuclei in many respects. One outstanding observation in exotic nuclei is the halo structure. The halo structure arises from the ...

  2. Excitation of pygmy dipole resonance in neutron-rich nuclei via ...

    Indian Academy of Sciences (India)

    3Departamento de FAMN, Facultad de Fısica, Sevilla, Spain. *Corresponding author. E-mail: vitturi@pd.infn.it. Abstract. We study the nature of the low-lying dipole strength in neutron-rich nuclei, often associated with the pygmy dipole resonance. The states are described within the. Hartree–Fock plus RPA formalism, using ...

  3. Experimental studies of unbound neutron-rich nuclei

    International Nuclear Information System (INIS)

    Lecouey, J.L.

    2003-10-01

    The three-body description of two-neutron halo nuclei relies on the two-body interactions between the constituents. In order to provide constraints on calculations devoted to 14 Be and 17 B, the neutron unbound states of 13 Be and 16 B have been investigated by one-proton knockout. The experimental techniques and results are discussed here. (author)

  4. Direct mass measurements of light neutron-rich nuclei using fast recoil spectrometers

    International Nuclear Information System (INIS)

    Vieira, D.J.; Wouters, J.M.

    1987-01-01

    Extensive new mass measurement capabilities have evolved with the development of recoil spectrometers. In the Z = 3 to 9 neutron-rich region alone, 12 neutron-rich nuclei have been determined for the first time by the fast-recoil direct mass measurement method. A recent experiment using the TOFI spectrometer illustrates this technique. A systematic investigation of nuclei that lie along or near the neutron-drip line has provided a valuable first glimpse into the nuclear structure of such nuclei. No evidence for a large single-particle energy gap at N = 14 is observed; however, a change in the two-neutron separation model calculations, and is interpreted in terms of the smaller 1s/sub 1/2/ - 1s/sub 1/2/ interaction compared to that of the 0d/sub 5/2/ - 0d/sub 5/2/ neutron-neutron interaction. 18 refs., 7 figs., 1 tab

  5. GALS – setup for production and study of heavy neutron rich nuclei

    Directory of Open Access Journals (Sweden)

    Zemlyanoy Sergey

    2015-01-01

    Full Text Available The present limits of the upper part of the nuclear map are very close to stability while the unexplored area of heavy neutron-rich nuclides along the neutron closed shell N = 126 below 208Pb is extremely important for nuclear astrophysics investigations and, in particular, for the understanding of the r-process of astrophysical nucleosynthesis. This area of the nuclear map can be reached neither in fusion–fission reactions nor in fragmentation processes widely used nowadays for the production of exotic nuclei. A new way was recently proposed for the production of these nuclei via low-energy multi-nucleon transfer reactions. The estimated yields of neutron-rich nuclei are found to be significantly high in such reactions and several tens of new nuclides can be produced, for example, in the near-barrier collision of 136Xe with 208Pb. A new setup is proposed to produce and study heavy neutron-rich nuclei located along the neutron closed shell N=126.

  6. Production and study of heavy neutron rich nuclei formed in multi-nucleon transfer reactions

    Energy Technology Data Exchange (ETDEWEB)

    Zagrebaev, V. I.; Zemlyanoy, S. G., E-mail: zemlya@jinr.ru; Kozulin, E. M. [Joint Institute for Nuclear Research, FLNR (Russian Federation); Kudryavtsev, Yu. [Instituut voor Kern-en Stralingsfysica (Belgium); Fedosseev, V. [CERN (Switzerland); Bark, R. [Nat. Research Foundation, iThemba LABS (South Africa); Othman, H. A. [Menoufiya University, Physics Department, Faculty of Science (Egypt)

    2013-04-15

    A new setup is proposed to produce and investigate heavy neutron-rich nuclei located along the neutron closed shell N = 126. This 'blank spot' of the nuclear map can be reached neither in fusion-fission reactions nor in fragmentation processes widely used nowadays for the production of exotic nuclei. The present limits of the upper part of the nuclear map are very close to stability while the unexplored area of heavy neutron-rich nuclides along the neutron closed shell N = 126 is extremely important for nuclear astrophysics investigations and, in particular, for the understanding of the r-process of astrophysical nucleosynthesis. A new way was recently proposed for the production of these nuclei via low-energy multi-nucleon transfer reactions. The estimated yields of neutron-rich nuclei are found to be rather high in such reactions and several tens of new nuclides can be produced, for example, in the near-barrier collision of 136Xe with 208Pb. This setup could definitely open a new opportunity in the studies at heavy-ion facilities and will have significant impact on future experiments.

  7. GALS – setup for production and study of heavy neutron rich nuclei

    CERN Document Server

    Zemlyanoy, Sergey; Kozulin, Eduard; Kudryavtsev, Yury; Fedosseev, Valentin; Bark, Robert; Janas, Zenon; Othman, Hosam

    2015-01-01

    The present limits of the upper part of the nuclear map are very close to stability while the unexplored area of heavy neutron-rich nuclides along the neutron closed shell N = 126 below ^208Pb is extremely important for nuclear astrophysics investigations and, in particular, for the understanding of the r-process of astrophysical nucleosynthesis. This area of the nuclear map can be reached neither in fusion-fission reactions nor in fragmentation processes widely used nowadays for the production of exotic nuclei. A new way was recently proposed for the production of these nuclei via low-energy multi-nucleon transfer reactions. The estimated yields of neutron-rich nuclei are found to be significantly high in such reactions and several tens of new nuclides can be produced, for example, in the near-barrier collision of ^136Xe with ^208Pb. A new setup is proposed to produce and study heavy neutron-rich nuclei located along the neutron closed shell N=126.

  8. Fifth International Conference on Fission and Properties of Neutron-Rich Nuclei

    CERN Document Server

    Ramayya, A V; ICFN5

    2014-01-01

    These proceedings are the fifth in the series of International Conferences covering fission and properties of neutron-rich nuclei, which are at the forefront of nuclear research. The time interval of 5 years between each conference allows for significant new results to be achieved. Recently, world leaders in theory and experiments in research and the development of new facilities for research presented their latest results in areas such as synthesis of superheavy elements, new facilities for and recent results with radioactive ion beams, structure of neutron-rich nuclei, nuclear fission process, fission yields and nuclear astrophysics. This book is a major source of the latest research in these areas and plans for the future. The conference brought together a unique group of over 100 speakers including leaders from the major nuclear laboratories in Canada, China, France, Finland, Germany, Italy, Japan, Russia, Switerzland and the US along with leading research scientists from around the world.

  9. Investigation of correlations in light neutron-rich nuclei

    International Nuclear Information System (INIS)

    Normand, G.

    2004-10-01

    Correlations play a crucial role in understanding the structure of light nuclei at and beyond the neutron drip-line. In this context, the two-neutron halo nucleus He 6 and the unbound systems H 5 , He 7,9 and Li 10 have been studied via measurements of the breakup of beams of He 6 and Be 11,12 . The CHARISSA and DEMON detector arrays were employed. The interpretation was facilitated by a simulation code (SILLAGE) which provided for the setup. In the case of He 7 , the existence of an excited state with E r ∼ 1 MeV and gamma ∼ 0.75 MeV was confirmed. The virtual character of the s-wave ground state of Li 10 was also confirmed and a scattering length of as ∼ -16 fm deduced. The results obtained for He 9 suggest that a virtual s-wave state may exist just above threshold. The study of the three-body breakup of He 6 found that the decay of the first 2+ state is essentially direct, while the decay of the remaining continuum strength is sequential - passage via He 5 . Using the technique of intensity interferometry an rms separation between the halo neutrons of 7.7 +- 0.8 fm was derived. This result was confirmed by a complementary method utilizing Dalitz plots. In the case of H 5 , the invariant mass spectrum was found to exhibit a broad (gamma ∼ 2 MeV) structure some 1.8 MeV above threshold. Comparison with recent three-body model calculations suggest that this corresponds to the predicted 1/2+ ground state. An rms valence neutron separation of some 5.5 fm was estimated. A search was also carried out for the 4n system using the Be 12* (2 alpha + Xn decay channel). No signal was observed beyond that expected on the basis of the known background processes. (author)

  10. Studies of neutron-rich nuclei far from stability at TRISTAN

    International Nuclear Information System (INIS)

    Gill, R.L.

    1984-01-01

    The ISOL facility, TRISTAN, is a user facility located at Brookhaven National Laboratory's High Flux Beam Reactor. Short-lived, neutron-rich nuclei, far from stability, are produced by thermal neutron fission of 235 U. An extensive array of experimental end stations are available for nuclear structure studies. These studies are augmented by a variety of long-lived ion sources suitable for use at a reactor facility. Some recent results at TRISTAN are presented as examples of using an ISOL facility to study series of nuclei, whereby an effective means of conducting nuclear structure investigations is available

  11. Two-Neutron Separation Energies Of Even-Even Rare-Earth Neutron-Rich Nuclei

    International Nuclear Information System (INIS)

    Benhamouda, N.; Oudih, M. R.; Allal, N. H.; Fellah, M.

    2007-01-01

    The variation of the two-neutron separation energy (S2N), as a function of N, is studied using a microscopic model that includes the pairing effects rigorously within the Fixed-Sharp-BCS method. The model has been tested for ''ordinary'' nuclei and has correctly reproduced the experimental data. The study has then been extended to the neutron-rich nuclei and has shown a relatively important variation of S2N when N= 100 which may be attributed to the existence of a new magic number

  12. Precision Mass Measurements of Neutron-Rich Rare-Earth Nuclei

    Science.gov (United States)

    Orford, Rodney; Buchinger, Fritz; Clark, Jason; Klimes, Jeffrey; Burkey, Mary; Savard, Guy; Gorelov, Dmitry; Sharma, Kumar

    2017-09-01

    One of the open problems in nuclear astrophysics is the identification of the astrophysical site of the rapid neutron capture process (r process). Due to the lack of experimental nuclear data of neutron-rich nuclei far from stability, it remains difficult to constrain or judge the accuracy of r-process models and calculations. The Canadian Penning Trap mass spectrometer (CPT) is located in the CARIBU facility at Argonne National Laboratory where intense beams of neutron-rich isotopes are created from the spontaneous fission of a 252Cf source. The implementation of a phase-imaging mass measurement technique (PI-ICR) at the CPT in conjunction with the MR-TOF mass separator at CARIBU has improved our experimental sensitivity by more than two orders of magnitude. Recently, PI-ICR was used to make the first direct mass measurements of a number of neutron-rich rare-earth isotopes near N = 100. The phase-imaging technique, and insights from these new masses into possible r-process sites will be discussed. This work was supported by the following: NSERC SAPPJ-2015-034, NSF Grants PHY-1419765 and PHY-14330152, and the U.S. Department of Energy, Office of Nuclear Physics. This research used resources of ANL's ATLAS facility.

  13. Shape evolution in neutron-rich A ~ 140 nuclei beyond the doubly-magic nucleus 132Sn

    Science.gov (United States)

    Odahara, Atsuko; Eurica Collaboration

    2014-09-01

    Study for the shape evolution enables us to disentangle competition between spherical (single-particle like) shape and deformed (collective-like) shape as a function of neutron number. Neutron-rich nuclei in the northeast region of the doubly-magic 132Sn locates in one of the best mass region where a variety of collective modes, not only prolate deformation but also octupole collectivity, are expected to appear. These neutron-rich A ~140 nuclei were produced by using in-flight fission reaction of the 345 MeV/u 238U86+ beam at RIKEN RI Beam Factory. This experiment was performed in the framework of the EURICA (EUroball RIken Cluster Array) project based on the highly-efficient β- and isomer-decay spectroscopy methods. Around 20 extremely neutron-rich nuclei with Z=51--55 have been studied in this work. New isomers with half lives of longer than hundreds ns were found in some nuclei, such as the neutron-rich Cs isotopes. Also, preliminary results for the β decay of neutron-rich I and Xe isotopes have been obtained. Systematic change of the shape evolution for these neutron-rich isotopes will be discussed.

  14. Relative mass distributions of neutron-rich thermally fissile nuclei within a statistical model

    Science.gov (United States)

    Kumar, Bharat; Kannan, M. T. Senthil; Balasubramaniam, M.; Agrawal, B. K.; Patra, S. K.

    2017-09-01

    We study the binary mass distribution for the recently predicted thermally fissile neutron-rich uranium and thorium nuclei using a statistical model. The level density parameters needed for the study are evaluated from the excitation energies of the temperature-dependent relativistic mean field formalism. The excitation energy and the level density parameter for a given temperature are employed in the convolution integral method to obtain the probability of the particular fragmentation. As representative cases, we present the results for the binary yields of 250U and 254Th. The relative yields are presented for three different temperatures: T =1 , 2, and 3 MeV.

  15. Fusion between heavy neutron-rich nuclei using radioactive and stable ion beams

    Energy Technology Data Exchange (ETDEWEB)

    Shapira, D.; Liang, J.F.; Gross, C.J.; Beene, J.R.; Varner, R.L.; Galindo U, A.; Gomez del Campo, J.; Mueller, P.E.; Stracener, D. W. [Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Amro, H.; Kolata, J.J. [Physics Department, University of Notre Dame, Notre Dame, IN 46556 (United States); Bierman, J.D. [Physics Department AD-51, Gonzaga Universiy, Spokane, WA 99258-0051 (United States); Caraley, A.L. [Department of Physics, State University of New York at Oswego, Oswego, NY 13126 (United States); Chavez L, E.; Ortiz, M.E. [lFUNAM, 04510 Mexico D.F. (Mexico); Jones, K.L. [Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08856 (United States); Loveland, W.; Sprunger, P.H.; Vinodkumar, A.M. [Department of Chemistry, Oregon State University, Corvallis, OR 97331 (United States)

    2007-12-15

    Evaporation residues (ERs) and fission products were measured following bombardment of {sup 64}Ni with radioactive Sn and Te neutron rich isotopes. The experimental setup was tailored to measurements with low intensity radioactive beams and the data obtained show the obvious enhancement of ER production (survival) with the addition of neutrons to the fused system. A calculation of nucleus-nucleus capture within a WKB formalism incorporating neutron transfer in a two step approach was performed. Using global potentials in our calculations we attempted to predict trends as well as account for measured capture cross sections of collisions between heavy nuclei with large neutron excess. (Author)

  16. Coulomb Excitation of Neutron-Rich $A\\approx$140 Nuclei

    CERN Multimedia

    Van duppen, P L E

    2002-01-01

    Investigating the isospin dependence of the product between the B( E2; 0$_{1}^{+} \\rightarrow 2_{1}^{+}$)-value and the 2$_{1}^{+}$-excitation energy E$_{2^{+}}$ in even-even nuclei around $A\\!\\approx$140 one observes a rather smooth trend close to the valley of stability but clear indication for a reduction from the extrapolated B(E2)-values by one order of magnitude for some very neutron-rich nuclei. While close to the valley of stability the strong neutron-proton interaction results in an equilibration of the neutron and proton deformations with a predominate isoscalar character of the collective 2$^{+}$ excitation, it is conceivable that more loosely bound neutrons cannot polarize a close-to-magic proton core that well any more. This might result in a decoupling of the shape of the outer neutrons from the core and in a strong isovector admixture to the lowest lying 2$^{+}$ level. In this way the 2$^{+}$ -energies could be further lowered in neutron-rich nuclei, while the quadrupole moments of the proton c...

  17. Cluster-transfer reactions with radioactive beams: a spectroscopic tool for neutron-rich nuclei

    CERN Document Server

    AUTHOR|(CDS)2086156; Raabe, Riccardo; Bracco, Angela

    In this thesis work, an exploratory experiment to investigate cluster-transfer reactions with radioactive beams in inverse kinematics is presented. The aim of the experiment was to test the potential of cluster-transfer reactions at the Coulomb barrier, as a possible mean to perform $\\gamma$ spectroscopy studies of exotic neutron-rich nuclei at medium-high energies and spins. The experiment was performed at ISOLDE (CERN), employing the heavy-ion reaction $^{98}$Rb + $^{7}$Li at 2.85 MeV/A. Cluster-transfer reaction channels were studied through particle-$\\gamma$ coincidence measurements, using the MINIBALL Ge array coupled to the charged particle Si detectors T-REX. Sr, Y and Zr neutron-rich nuclei with A $\\approx$ 100 were populated by either triton- or $\\alpha$ transfer from $^{7}$Li to the beam nuclei and the emitted complementary charged fragment was detected in coincidence with the $\\gamma$ cascade of the residues, after few neutrons evaporation. The measured $\\gamma$ spectra were studied in detail and t...

  18. One-neutron knockout from light neutron-rich nuclei at relativistic energies

    International Nuclear Information System (INIS)

    Rodriguez-Tajes, C.; Alvarez-Pol, H.; Benjamim, E.; Benlliure, J.; Caamano, M.; Casarejos, E.; Cortina-Gil, D.; Gascon, M.; Kurtukian, T.; Perez-Loureiro, D.; Aumann, T.; Chatillon, A.; Geissel, H.; Nociforo, C.; Prochazka, A.; Simon, H.; Suemmerer, K.; Weick, H.; Winkler, M.; Borge, M. J. G.

    2010-01-01

    One-neutron knockout reactions from neutron-rich nuclei, with Z=6-13 and N=8-22, were studied at the Fragment Separator (GSI) at high beam energies, around 700 MeV/nucleon. Structural phenomena such as the formation of one-neutron halos in odd-mass carbon isotopes ( 15,17,19 C) will be discussed. In addition, one-neutron knockout measurements from 22 N were carried out for the first time and demonstrate clearly the change from a 0d 5/2 to a 1s 1/2 orbital for the valence neutron, an effect that is expected above N=14 and that was also observed in 23 O and 24 F. The possibility of an anomalous structure of 26 F, due to a significant 1s 1/2 neutron admixture, will also be discussed in the light of the experimental data obtained in this work. Finally, the ground-state configuration of neutron-rich neon isotopes ( 24-28 Ne) was studied, providing new information in a region that is relatively close to the island of inversion.

  19. Dipole response in neutron-rich nuclei within self-consistent approaches using realistic potentials

    Directory of Open Access Journals (Sweden)

    Lo Iudice N.

    2015-01-01

    Full Text Available A nucleon-nucleon chiral potential with a corrective density dependent term simulating a three-body force is used in a self-consistent calculation of the dipole strength distribution in neutron-rich nuclei, with special attention to the low-lying spectra associated to the pygmy resonance. A Hartree-Fock-Bogoliubov basis is generated and adopted in Tamm-Dancoff and random-phase approximations and, then, in an equation of motion approach which includes a basis of two-phonon states. The direct use of the mentioned chiral potential improves the description of both giant and pygmy dipole modes with respect to other realistic interactions. Moreover, the inclusion of the two-phonon states induces a pronounced fragmentation of the giant resonance and enhances the density of the low-lying levels in the pygmy region in agreement with recent experiments.

  20. Symmetry energy and surface properties of neutron-rich exotic nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Gaidarov, M. K.; Antonov, A. N. [Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences, Sofia 1784 (Bulgaria); Sarriguren, P. [Instituto de Estructura de la Materia, IEM-CSIC, Serrano 123, E-28006 Madrid (Spain); Moya de Guerra, E. [Departamento de Fisica Atomica, Molecular y Nuclear, Facultad de Ciencias Fisicas, Universidad Complutense de Madrid, E-28040 Madrid (Spain)

    2014-07-23

    The symmetry energy, the neutron pressure and the asymmetric compressibility of spherical Ni, Sn, and Pb and deformed Kr and Sm neutron-rich even-even nuclei are calculated within the coherent density fluctuation model using the symmetry energy as a function of density within the Brueckner energy-density functional. The correlation between the thickness of the neutron skin and the characteristics related with the density dependence of the nuclear symmetry energy is investigated for isotopic chains of these nuclei in the framework of the deformed self-consistent mean-field Skyrme HF+BCS method. The mass dependence of the nuclear symmetry energy and the neutron skin thickness are also studied together with the role of the neutron-proton asymmetry. The studied correlations reveal a smoother behavior in the case of spherical nuclei than for deformed ones. We also notice that the neutron skin thickness obtained for {sup 208}Pb with SLy4 force is found to be in a good agreement with the recent data. In addition to the interest that this study may have by itself, we give some numerical arguments in proof of the existence of peculiarities of the studied quantities in Ni and Sn isotopic chains that are not present in the Pb chain.

  1. Interplay between collective and single particle excitations around neutron-rich doubly-magic nuclei

    Directory of Open Access Journals (Sweden)

    Leoni S.

    2016-01-01

    Full Text Available The excitation spectra of nuclei with one or two particles outside a doubly-magic core are expected to be dominated, at low energy, by the couplings between phonon excitations of the core and valence particles. A survey of the experimental situation is given for some nuclei lying in close proximity of neutron-rich doubly-magic systems, such as 47,49Ca, 133Sb and 210Bi. Data are obtained with various types of reactions (multinucleon transfer with heavy ions, cold neutron capture and neutron induced fission of 235U and 241Pu targets, with the employment of complex detection systems based on HPGe arrays. A comparison with theoretical calculations is also presented, in terms of large shell model calculations and of a phenomenological particle-phonon model. In the case of 133Sb, a new microscopic “hybrid” model is introduced: it is based on the coupling between core excitations (both collective and non-collective of the doubly-magic core and the valence nucleon, using the Skyrme effective interaction in a consistent way.

  2. Antisymmetrized molecular dynamics studies for exotic clustering phenomena in neutron-rich nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Kimura, M. [Hokkaido University, Department of Physics, Sapporo (Japan); Hokkaido University, Nuclear Reaction Data Centre, Faculty of Science, Sapporo (Japan); Suhara, T. [Matsue College of Technology, Matsue (Japan); Kanada-En' yo, Y. [Kyoto University, Department of Physics, Kyoto (Japan)

    2016-12-15

    We present a review of recent works on clustering phenomena in unstable nuclei studied by antisymmetrized molecular dynamics (AMD). The AMD studies in these decades have uncovered novel types of clustering phenomena brought about by the excess neutrons. Among them, this review focuses on the molecule-like structure of unstable nuclei. One of the earliest discussions on the clustering in unstable nuclei was made for neutron-rich Be and B isotopes. AMD calculations predicted that the ground state clustering is enhanced or reduced depending on the number of excess neutrons. Today, the experiments are confirming this prediction as the change of the proton radii. Behind this enhancement and reduction of the clustering, there are underlying shell effects called molecular and atomic orbits. These orbits form covalent and ionic bonding of the clusters analogous to the atomic molecules. It was found that this ''molecular-orbit picture'' reasonably explains the low-lying spectra of Be isotopes. The molecular-orbit picture is extended to other systems having parity asymmetric cluster cores and to the three cluster systems. O and Ne isotopes are the candidates of the former, while the 3α linear chains in C isotopes are the latter. For both subjects, many intensive studies are now in progress. We also pay a special attention to the observables which are the fingerprint of the clustering. In particular, we focus on the monopole and dipole transitions which are recently regarded as good probe for the clustering. We discuss how they have and will reveal the exotic clustering. (orig.)

  3. Nuclear shell effects in neutron-rich nuclei around N=20 and N=32,34

    CERN Document Server

    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...

  4. Shape of 44Ar: Onset of deformation in neutron-rich nuclei near 48Ca

    International Nuclear Information System (INIS)

    Zielinska, M.; Goergen, A.; Clement, E.; Korten, W.; Dossat, C.; Ljungvall, J.; Obertelli, A.; Theisen, Ch.; Delaroche, J.-P.; Girod, M.; Buerger, A.; Catford, W.; Iwanicki, J.; Napiorkowski, P. J.; Srebrny, J.; Wrzosek, K.; Libert, J.; PiePtak, D.; Rodriguez-Guzman, R.; Sletten, G.

    2009-01-01

    The development of deformation and shape coexistence in the vicinity of doubly magic 48 Ca, related to the weakening of the N=28 shell closure, was addressed in a low-energy Coulomb excitation experiment using a radioactive 44 Ar beam from the SPIRAL facility at GANIL. The 2 1 + and 2 2 + states in 44 Ar were excited on 208 Pb and 109 Ag targets at two different beam energies. B(E2) values between all observed states and the spectroscopic quadrupole moment of the 2 1 + state were extracted from the differential Coulomb excitation cross sections, indicating a prolate shape of the 44 Ar nucleus and giving evidence of an onset of deformation already two protons and two neutrons away from doubly magic 48 Ca. New Hartree-Fock-Bogoliubov based configuration mixing calculations have been performed with the Gogny D1S interaction for 44 Ar and neighboring nuclei using two different approaches: the angular momentum projected generator coordinate method considering axial quadrupole deformations and a five-dimensional approach including the triaxial degree of freedom. The experimental values and new calculations are furthermore compared to shell-model calculations and to relativistic mean-field calculations. The new results give insight into the weakening of the N=28 shell closure and the development of deformation in this neutron-rich region of the nuclear chart.

  5. Spectroscopy of neutron-rich nuclei produced in the spontaneous fission of californium-252

    Science.gov (United States)

    Simon, Michael Wilhelm

    1999-10-01

    A new experimental technique has been developed for the spectroscopic investigation of the neutron-rich products of 252Cf(SF). The charged-particle detector CHICO was coupled to the Ge-detector array GAMMASPHERE and a thin fission source was used allowing the collection of high-statistics, high-fold γ-ray data in kinematic coincidence with the recoiling fission partners. The selectivity provided by this technique allows the γ-rays to be assigned unambiguously to the heavy or light fission partner. The added sensitivity allows many rotational bands to be extended to ~20 ħ, and a sensitivity to nuclei produced with a yield of 5 × 10-5 /fission was achieved by mass-gating the γ-ray spectra. The charged-particle detector CHICO was developed for this experiment and for studies utilizing other binary reactions, such as Coulomb excitation, transfer and fusion-fission reactions. The detector covers a total solid angle of 2.8 sr and has a time resolution of 500 ps, resulting in a mass resolution of Δm/m = 5% for beam experiments, or 8 mass units for spontaneous fission. This technique was used to set limits, in agreement with shell model predictions, on the E3 decay of the / - level in 135I. Rotational bands in 102,104,106,108Mo, 112Ru, 152,154,156 Nd, 156,158,160Sm were extended to higher spin. Band crossings were observed in the ground and γ-band in 104Mo. The γ-band of 112Ru shows continued tri-axial behavior at higher spin. The yrast rotational bands in 112,113,114,115,116 Pd were extended and rotational bands built on the low-lying isomeric levels in 113,115Pd were newly identified. The behavior of the observed band crossings in the ground and isomer bands of 113,115 Pd, when compared to the neighboring 111,113 Rh and cranked shell model calculations indicate that the predicted change from prolate to oblate shapes in the neutron-rich Pd does not occur before 116Pd. In a separate experiment, the lifetimes in 165Ho of the K=/ - ground band, up to spin / - ħ, and

  6. New approach to the nuclear in beam γ spectroscopy of neutron rich nuclei at N=20 using projectile fragmentation

    International Nuclear Information System (INIS)

    Lopez-Jimenez, M.J.; Saint-Laurent, M.G.; Achouri, L.; Daugas, J.M.; Belleguic, M.; Azaiez, F.; Bourgeois, C.; Angelique, J.C.

    1999-01-01

    The structure of nuclei far from stability around 32 Mg have been recently investigated by means of a novel method. In-beam γ-decay spectroscopy of a large number of exotic neutron-rich nuclei produced by projectile fragmentation of a 36 S projectile has been performed, using coincidences between the recoil fragments collected at the focal plane of SPEG spectrometer and γ-rays emitted at the target location. Preliminary results on both the population mechanism and the decay of excited states in nuclei around 32 Mg are presented. (author)

  7. Empirical parametrization for production cross sections of neutron-rich nuclei by photofission of 238U at low energies

    Science.gov (United States)

    Mei, B.; Balabanski, D. L.; Constantin, P.; Anh, L. T.; Cuong, P. V.

    2017-12-01

    An empirical parametrization for the production cross sections of 238U photofission fragments at low energies (Eγelemental and mass yields and can accurately reproduce experimental isotopic yields. Production cross sections (yields) of photofission fragments calculated by this parametrization indicate that many neutron-rich nuclei approaching the r -process path can be accessed via photofission of 238U at radioactive-beam facilities.

  8. Quasifree (p ,p N ) scattering of light neutron-rich nuclei near N =14

    Science.gov (United States)

    Díaz Fernández, P.; Alvarez-Pol, H.; Crespo, R.; Cravo, E.; Atar, L.; Deltuva, A.; Aumann, T.; Avdeichikov, V.; Beceiro-Novo, S.; Bemmerer, D.; Benlliure, J.; Bertulani, C. A.; Boillos, J. M.; Boretzky, K.; Borge, M. J. G.; Caamaño, M.; Cabanelas, P.; Caesar, C.; Casarejos, E.; Catford, W.; Cederkäll, J.; Chartier, M.; Chulkov, L. V.; Cortina-Gil, D.; Datta Pramanik, U.; Dillmann, I.; Elekes, Z.; Enders, J.; Ershova, O.; Estradé, A.; Farinon, F.; Fernández-Domínguez, B.; Fraile, L. M.; Freer, M.; Galaviz, D.; Geissel, H.; Gernhäuser, R.; Golubev, P.; Göbel, K.; Hagdahl, J.; Heftrich, T.; Heil, M.; Heine, M.; Heinz, A.; Henriques, A.; Holl, M.; Hufnagel, A.; Ignatov, A.; Johansson, H. T.; Jonson, B.; Jurčiukonis, D.; Kalantar-Nayestanaki, N.; Kanungo, R.; Kelic-Heil, A.; Knyazev, A.; Kröll, T.; Kurz, N.; Labiche, M.; Langer, C.; Le Bleis, T.; Lemmon, R.; Lindberg, S.; Machado, J.; Marganiec, J.; Moro, A. M.; Movsesyan, A.; Nacher, E.; Najafi, A.; Nikolskii, E.; Nilsson, T.; Nociforo, C.; Panin, V.; Paschalis, S.; Perea, A.; Petri, M.; Pietras, B.; Pietri, S.; Plag, R.; Reifarth, R.; Ribeiro, G.; Rigollet, C.; Rossi, D.; Röder, M.; Savran, D.; Scheit, H.; Simon, H.; Sorlin, O.; Syndikus, I.; Taylor, J. T.; Tengblad, O.; Thies, R.; Togano, Y.; Vandebrouck, M.; Velho, P.; Volkov, V.; Wagner, A.; Wamers, F.; Weick, H.; Wheldon, C.; Wilson, G.; Winfield, J. S.; Woods, P.; Yakorev, D.; Zhukov, M.; Zilges, A.; Zuber, K.; R3B Collaboration

    2018-02-01

    Background: For many years, quasifree scattering reactions in direct kinematics have been extensively used to study the structure of stable nuclei, demonstrating the potential of this approach. The R 3B collaboration has performed a pilot experiment to study quasifree scattering reactions in inverse kinematics for a stable 12C beam. The results from that experiment constitute the first quasifree scattering results in inverse and complete kinematics. This technique has lately been extended to exotic beams to investigate the evolution of shell structure, which has attracted much interest due to changes in shell structure if the number of protons or neutrons is varied. Purpose: In this work we investigate for the first time the quasifree scattering reactions (p ,p n ) and (p ,2 p ) simultaneously for the same projectile in inverse and complete kinematics for radioactive beams with the aim to study the evolution of single-particle properties from N =14 to N =15 . Method: The structure of the projectiles 23O, 22O, and 21N has been studied simultaneously via (p ,p n ) and (p ,2 p ) quasifree knockout reactions in complete inverse kinematics, allowing the investigation of proton and neutron structure at the same time. The experimental data were collected at the R3B -LAND setup at GSI at beam energies of around 400 MeV/u. Two key observables have been studied to shed light on the structure of those nuclei: the inclusive cross sections and the corresponding momentum distributions. Conclusions: The knockout reactions (p ,p n ) and (p ,2 p ) with radioactive beams in inverse kinematics have provided important and complementary information for the study of shell evolution and structure. For the (p ,p n ) channels, indications of a change in the structure of these nuclei moving from N =14 to N =15 have been observed, i.e., from the 0 d5 /2 shell to the 1 s1 /2 . This supports previous observations of a subshell closure at N =14 for neutron-rich oxygen isotopes and its weakening

  9. Statistical properties of warm nuclei: Investigating the low-energy enhancement in the $\\gamma$- strength function of neutron-rich nuclei

    CERN Multimedia

    We propose to start a program to study the $\\gamma$-ray strength function of neutron rich nuclei in inverse kinematics with radioactive beams at HIE-ISOLDE. An unexpected increase in the $\\gamma$-strength function at low energy has been observed in several stable nuclei using the Oslo method. This year these results were confirmed with a different experimental technique and model independent analysis developed by iThemba/Livermore. If this enhancement of the $\\gamma$-strength function is also present in neutron-rich nuclei, it will strongly affect the neutron capture cross sections, which are important input in stellar models of synthesis of heavier elements in stars. We propose to start with an experiment using a $^{66}$Ni beam of 5.5 MeV /u, where the data will be analyzed using both methods independently, and we are sure to get enough statistics, before moving to more neutron-rich nuclei. When/if neutron-rich Ti, Fe or Mo beams will be available at ISOLDE, we will submit additional proposals.

  10. Octupole deformation in neutron-rich actinides and superheavy nuclei and the role of nodal structure of single-particle wavefunctions in extremely deformed structures of light nuclei

    Science.gov (United States)

    Afanasjev, A. V.; Abusara, H.; Agbemava, S. E.

    2018-03-01

    Octupole deformed shapes in neutron-rich actinides and superheavy nuclei as well as extremely deformed shapes of the N∼ Z light nuclei have been investigated within the framework of covariant density functional theory. We confirmed the presence of new region of octupole deformation in neutron-rich actinides with the center around Z∼ 96,N∼ 196 but our calculations do not predict octupole deformation in the ground states of superheavy Z≥slant 108 nuclei. As exemplified by the study of 36Ar, the nodal structure of the wavefunction of occupied single-particle orbitals in extremely deformed structures allows to understand the formation of the α-clusters in very light nuclei, the suppression of the α-clusterization with the increase of mass number, the formation of ellipsoidal mean-field type structures and nuclear molecules.

  11. Beta spectroscopy on neutron-rich nuclei of mass 93<=A<=100

    International Nuclear Information System (INIS)

    Pahlmann, B.

    1982-01-01

    In the present thesis for the first time measurements of the Qsub(β) value of the neutron-rich fission products sup(99,100)Sr and 99 Rb were performed. Preliminary results could be obtained on the beta decays of the nuclides 100 Rb and 100 Y. (orig./HSI) [de

  12. Spectroscopy of neutron rich nuclei using cold neutron induced fission of actinide targets at the ILL: the EXILL campaign

    Directory of Open Access Journals (Sweden)

    de France G.

    2014-03-01

    Full Text Available A combination of germanium detectors has been installed at the PF1B neutron guide of the ILL to perform the prompt spectroscopy of neutron-rich nuclei produced in the neutron-capture induced-fission of 235U and 241Pu. In addition LaBr3 detectors from the FATIMA collaboration have been installed in complement with the EXOGAM clovers to measure lifetimes of low-lying excited states. The measured characteristics and online spectra indicate very good performances of the overall setup.

  13. Nuclear structure studies of medium-mass nuclei using large Ge arrays

    International Nuclear Information System (INIS)

    Baktash, C.

    1996-01-01

    The advent of large Ge arrays and their ancillary detectors has greatly advanced spectroscopic studies of the medium-mass nuclei. These nuclei undergo rapid shape changes as a function of spin, excitation energy and particle number and, thus, provide a unique laboratory to test and refine a variety of theoretical models. Following a brief review of the physics motivation, some of the highlights of the experimental results obtained with the help of these powerful detector systems will be discussed. Among results presented here are the newly-discovered island of superdeformation in the A∼80 mass region, and the high-spin band structures in the N∼Z nuclei. These band structures may be understood in the framework of the conventional cranking models, without the introduction of additional T=0 neutron-proton pairing correlations

  14. Semimicroscopic description of basic properties of isoscalar monopole and dipole excitations in medium-mass spherical nuclei

    NARCIS (Netherlands)

    Gorelik, ML; Urin, MH

    2003-01-01

    A description of basic properties (strength function, transition density, probabilities of direct nucleonic decays) of isoscalar giant monopole (including an overtone) and dipole resonances in medium-mass spherical nuclei is proposed within a semimicroscopic approach. The approach relies on

  15. High-spin transition quadrupole moments in neutron-rich Mo and Ru nuclei: Testing γ softness?

    Energy Technology Data Exchange (ETDEWEB)

    Snyder, J.B. [Physics Department, Washington University, St. Louis, MO 63130 (United States); Reviol, W., E-mail: reviol@wustl.edu [Chemistry Department, Washington University, St. Louis, MO 63130 (United States); Sarantites, D.G. [Chemistry Department, Washington University, St. Louis, MO 63130 (United States); Afanasjev, A.V. [Department of Physics and Astronomy, Mississippi State University, Starkville, MS 39762 (United States); Janssens, R.V.F. [Physics Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Abusara, H. [Department of Physics, Faculty of Science, An-Najah National University, Nablus, Palestine (Country Unknown); Carpenter, M.P. [Physics Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Chen, X. [Chemistry Department, Washington University, St. Louis, MO 63130 (United States); Chiara, C.J. [Physics Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742 (United States); Greene, J.P.; Lauritsen, T. [Physics Division, Argonne National Laboratory, Argonne, IL 60439 (United States); McCutchan, E.A. [Physics Division, Argonne National Laboratory, Argonne, IL 60439 (United States); National Nuclear Data Center, Brookhaven National Laboratory, Upton, NY 11973 (United States); Seweryniak, D.; Zhu, S. [Physics Division, Argonne National Laboratory, Argonne, IL 60439 (United States)

    2013-06-10

    The transition quadrupole moments, Q{sub t}, of rotational bands in the neutron-rich, even-mass {sup 102–108}Mo and {sup 108–112}Ru nuclei were measured in the 8–16 ℏ spin range with the Doppler-shift attenuation method. The nuclei were populated as fission fragments from {sup 252}Cf fission. The detector setup consisted of the Gammasphere spectrometer and the HERCULES fast-plastic array. At moderate spin, the Q{sub t} moments are found to be reduced with respect to the values near the ground states. Attempts to describe the observations in mean-field-based models, specifically cranked relativistic Hartree–Bogoliubov theory, illustrate the challenge theory faces and the difficulty to infer information on γ softness and triaxiality from the data.

  16. Identification of new neutron-rich rare-earth nuclei produced in /sup 252/Cf spontaneous fission

    CERN Document Server

    Greenwood, R C; Gehrke, R J; Meikrantz, D H

    1981-01-01

    A program of systematic study of the decay properties of neutron-rich rare-earth nuclei with 30 sneutron-rich rare-earth isotopes including /sup 155/Pm (t/sub 1/2/=48+or-4 s) and /sup 163/Gd (t/sub 1 /2/=68+or-3 s), in addition to 5.51 min /sup 158/Sm which was identified in an earlier series of experiments. (11 refs).

  17. Shape transitions in neutron rich 110-112Ru nuclei and empirical relations

    International Nuclear Information System (INIS)

    Bihari, Chhail; Singh, Yuvraj; Gupta, K.K.; Varshney, A.K.; Singh, M.; Gupta, D.K.

    2010-01-01

    In the study of even even neutron rich Ru isotopes, the electromagnetic properties of the γ-vibrational bands are well described by a rigid triaxial rotor for lower spin state and by the rotation vibration collective model for the higher spin states. Thus interpretation in further suggested by the observation of nearly identical moment of inertia, the rotational frequency below the first band crossing, between the ground state and the γ-structural bands for both 110 Ru and 112 Ru which conclude a weak pairing, a more likely suitable explanation of observations. In the present work, the soft rotor energy formula is undertaken suggested by Brentano et al. for yrast band, may be employed to calculate the perturbed energies of the anomalous rotational band (γ-band) generated by rotation of the rigid asymmetric atomic nucleus and the two parameter formula (TPF) of Gupta et al.

  18. Dipole resonances in light neutron-rich nuclei studied with time-dependent calculations of antisymmetrized molecular dynamics

    International Nuclear Information System (INIS)

    Kanada-En'yo, Y.; Kimura, M.

    2005-01-01

    To study isovector dipole responses of neutron-rich nuclei, we applied a time-dependent method of antisymmetrized molecular dynamics. The dipole resonances in Be, B, and C isotopes were investigated. In 10 Be, 15 B, and 16 C, collective modes of the vibration between a core and valence neutrons cause soft resonances at the excitation energy E x =10-15 MeV below the giant dipole resonance (GDR). In 16 C, we found that a remarkable peak at E x =14 MeV corresponds to the coherent motion of four valence neutrons against a 12 C core, whereas the GDR arises in the E x >20 MeV region because of vibration within the core. In 17 B and 18 C, the dipole strengths in the low-energy region decline compared with those in 15 B and 16 C. We also discuss the energy-weighted sum rule for the E1 transitions

  19. β-decay of neutron-rich Z∼60 nuclei and the origin of rare earth elements

    Energy Technology Data Exchange (ETDEWEB)

    Wu, J. [RIKEN Nishina Center, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan and School of Physics and State key Laboratory of Nuclear Physics and Technology, Peking University (China); Nishimura, S.; Lorusso, G.; Baba, H.; Doornenbal, P.; Isobe, T.; Söderström, P. A.; Sakurai, H. [RIKEN Nishina Center, 2-1 Hirosawa, Wako-shi, Saitama 351-0198 (Japan); Xu, Z. Y. [Department of Physics, University of Tokyo, Hongo 7-3-1, Bunkyo-ku, 113-0033 Tokyo (Japan); Browne, F. [School of Computing Engineering and Mathematics, University of Brighton (United Kingdom); Daido, R.; Fang, Y. F.; Yagi, A.; Nishibata, H.; Odahara, A.; Yamamoto, T. [Department of Physics, Osaka University, Machikaneyama-machi 1-1, Osaka 560-0043 Toyonaka (Japan); Ideguchi, E.; Aoi, N.; Tanaka, M. [Research Center for Nuclear Physics, Osaka University (Japan); Collaboration: EURICA Collaboration; and others

    2014-05-02

    A large fraction of the rare-earth elements observed in the solar system is produced in the astrophysical rapid neutron capture process (r-process). However, current stellar models cannot completely explain the relative abundance of these elements partially because of nuclear physics uncertainties. To address this problem, a β-decay spectroscopy experiment was performed at RI Beam Factory (RIBF) at RIKEN, aimed at studying a wide range of very neutron-rich nuclei with Z∼60 that are progenitors of the rare-earth elements with mass number A∼460. The experiment provides a test of nuclear models as well as experimental inputs for r-process calculations. This contribution presents the experimental setup and some preliminary results of the experiment.

  20. Mass-measurements far from stability of neutron rich light nuclei

    International Nuclear Information System (INIS)

    Mittig, W.; Gregoire, C.; Schutz, Y.

    1987-07-01

    The study of nuclei far from stability is a verification of nuclear models that generally have been established using the properties of stable nuclei. The direct measurement of the mass has considerable advantages for nuclei very far from stability. This implies a high resolution measurement device, reasonable production rates of the nuclei of interest, and very low systematic errors. This is discussed here. Some of the results have been published recently. They are compared to different classes of models. Region presented is Z=9-15 region

  1. Alpha decay and cluster decay of some neutron-rich actinide nuclei

    Indian Academy of Sciences (India)

    2017-02-09

    Feb 9, 2017 ... Abstract. Nuclei in the actinide region are good in exhibiting cluster radioactivity. In the present work, the half-lives of α-decay and heavy cluster emission from certain actinide nuclei have been calculated using cubic plus Yukawa plus exponential model (CYEM). Our model has a cubic potential for the ...

  2. I. Surface properties of neutron-rich nuclei. II. Pion condensation at finite temperature

    International Nuclear Information System (INIS)

    Kolehmainen, K.A.

    1983-01-01

    In part I, the energy density formalism, the Thomas-Fermi approximation, and Skyrme-type interactions were used to describe the energy density of a semi-infinite slab of neturon-rich nuclear matter at zero temperature. The existence of a drip phase at low proton fractions is allowed in addition to the more dense nuclear phase, and various bulk properties of both phases are found when the system is in equilibrium. The usual definition of the surface energy is extended to apply to the case where drip is present. Assuming a Fermi function type density profile, a constrained variational calculation is performed to determine the neutron and proton surface diffuseness parameters, the thickness of the neutron skin, and the surface energy. Results are obtained for proton fractions reanging from 0.5 (symmetric nuclear matter) to zero (pure neutron matter) for most Skyrme-type interactions in common use. The results are in close agreement with the predictions of the droplet model, as well as with the results of more exact calculations in those cases where the more exact results exist (only for symmetric or nearly symmetric matter in most cases). Significantly different asymmetry dependences for different interactions are found. In part II, several simple but increasingly complex models are used to calculate the threshold for charged pion condensation in neutron-rich nuclear matter at finite temperature. Unlike in mean field theory descriptions of pion condensation, the effects of thermal excitations of the pion field are included. The thermal pion excitations have two important effects: first, to modify the phase diagram qualitatively from that predicted by mean field theory, and second, to make the phase transition to a spatially nonuniform condensed state at finite temperature always first, rather than second, order

  3. Production and study of new neutron rich heavy nuclei in multinucleon transfer reactions

    Directory of Open Access Journals (Sweden)

    Zagrebaev V.I.

    2013-12-01

    Full Text Available Problems of production and study of new neutron-enriched heavy nuclei are discussed. Low-energy multinucleon transfer reactions are shown to be quite appropriate for this purpose. Reactions with actinide beams and targets are of special interest for synthesis of new neutron-enriched transfermium nuclei and not-yet-known nuclei with closed neutron shell N = 126 having the largest impact on the astrophysical r-process. The estimated cross sections for the production of these nuclei look very promising for planning such experiments at currently available accelerators. These experiments, however, are rather expensive and difficult to perform because of low intensities of the massive projectile beams and problems of separating and detecting the heavy reaction products. Thus, realistic predictions of the corresponding cross sections for different projectile-target combinations are definitely required. Some uncertainty still remains in the values of several parameters used for describing the low-energy nuclear dynamics. This uncertainty does not allow one to perform very accurate predictions for the productions of new heavier-than-target (trans-target nuclei in multinucle on transfer reactions. Nevertheless these predictions are rather promising (large cross sections to start such experiments at available accelerators if the problem of separation of heavy transfer reaction products would be solved.

  4. Direct mass and lifetime measurements of neutron-rich nuclei up to A∼100 using the TOFI spectrometer at LAMPF

    International Nuclear Information System (INIS)

    Lind, V.G.

    1993-01-01

    This project was directed toward the study of neutron-rich nuclei using the experimental facilities at LAMPF, which is a part of LANL. The principal results of the investigation include the discovery of many new isotopes along with a measurement of their masses and in particular those nuclides in the Z = 7--19 and 14 --26 regions of the chart of the nuclides.Thirty-four new nuclides were detected and studied with their masses being measured with relatively high accuracy, and an additional twenty-six that were previously known and measured were remeasured to an improved accuracy. Besides providing new information about the mass surface in new and extended redons of the chart of the nuclides, this investigation enabled properties and previously unknown structure of some of the nuclei to be determined such as nuclear deformation among some of the nuclides. Also a study of the neutron pairing gaps and the proton pairing gaps among these nuclides was made. Other developments also achieved included instrument (TOFI) improvements and upgrades and theoretical investigations into the masses of the hadrons

  5. Neutron skin thickness in neutron-rich nuclei: bulk and surface contributions and shell effects

    International Nuclear Information System (INIS)

    Vinas, X.; Centelles, M.; Warda, M.; Roca-Maza, X.

    2012-01-01

    We analyze theoretically the neutron skin thickness in nuclei and its correlation with the symmetry energy by using semiclassical and mean field approaches together with nuclear effective interactions. Semiclassical approaches reveal that the neutron skin thickness in nuclei is formed by a combination of bulk and surface contributions. To investigate the neutron skin thickness predicted by mean field models, we fit the corresponding densities by two-parameter Fermi distributions. Using these parametrized densities, we study the neutron skin thickness as well as its bulk and surface contributions in 208 Pb and in Zr isotopes, where the influence of shell effects along the isotopic chain is discussed. (author)

  6. High spin studies of neutron-rich nuclei produced in the spontaneous fission process of californium-252

    Science.gov (United States)

    Zhang, Xueqian

    2001-08-01

    From an experiment with GAMMMASPHERE and a 252Cf spontaneous fission source, high spin studies of several neutron-rich nuclei have been carried out. In the mass region A ~ 150, a new negative-parity band in 154Nd and new negative-parity levels in 152Nd were identified and the yrast bands were extended to 18+ in 154Nd and 20+ 152Nd in a triple gamma coincidence study. These new negative-parity bands are consistent with octupole vibrational mode rather than the stable octupole deformation seen in Ba and Ce nuclei. There is a constant difference as a function of spin between the J1 values for the negative-parity band in 152Nd and J1 for the similar negative-parity band in 154Nd, however, their J2 values are essentially identical above the 4 + state. These bands indicate a new kind of identical bands associated with an octupole vibrational mode. In mass region A ~ 110, we have observed new bands in 113,115,117,118 Pd up to moderately high spin. The newly identified negative-parity yrast band energy level systematics built on the / isomeric states fit smoothly with the known systematic for other Pd isotopes, and show a minimum excitation energy at N = 68 related to a mid-shell closure. These new negative- parity yrast bands indicate a first band crossing at ¢ω ~ 0.45 MeV, nearly identical to those seen in 109,111Pd, but significantly higher than those in the positive yrast parity bands in 113,115Pd and in the even-even Pd isotopes. We have interpreted the new negative-parity yrast bands as having band crossings from the alignment of a nh/ pair, and this suggests that 113,115,117Pd maintain a prolate shape. Additionally, we have observed two new bands in 113,115 Pd, which are tentatively assigned positive parity with band crossings about 0.25 and 0.32 MeV. These lower frequencies are consistent with a nh/ pair alignment. In the neutron-rich 118Pd, the first band crossing at a frequency of ¢ω ~ 0.29 MeV was observed in its yrast band. This band crossing frequency is

  7. Nuclear symmetry energy and the neutron skin in neutron-rich nuclei

    NARCIS (Netherlands)

    Dieperink, AEL; Dewulf, Y; Van Neck, D; Waroquier, M; Rodin, [No Value

    2003-01-01

    The symmetry energy for nuclear matter and its relation to the neutron. skin in finite nuclei is discussed. The symmetry energy as a function of density obtained in a self-consistent Green function approach is presented and compared to the results of other recent theoretical approaches. A partial

  8. Structure of light neutron-rich nuclei and mechanism of elastic proton scattering

    Energy Technology Data Exchange (ETDEWEB)

    Ibraeva, E. T., E-mail: ibr@inp.kz [National Nuclear Center of the Republic of Kazakhstan, Institute of Nuclear Physics (Kazakhstan); Zhusupov, M. A. [Al-Farabi Kazakh National University (Kazakhstan); Imambekov, O. [National Nuclear Center of the Republic of Kazakhstan, Institute of Nuclear Physics (Kazakhstan)

    2011-11-15

    Differential cross sections for elastic p{sup 6}He, p{sup 8}Li, and p{sup 9}Li scattering at two energies of 70 and 700 MeV per nucleon were calculated within the Glauber theory of multiple diffractive scattering. Threeparticle wave functions ({alpha}-n-n for {sup 6}He, {alpha}-t-n for {sup 8}Li, and {sup 7}Li-n-n for {sup 9}Li) were used for realistic potentials of intercluster interactions. The sensitivity of elastic scattering to proton-nucleus interaction and to the structure of nuclei was explored. In particular, the dependence of the differential cross section on the contribution of higher order collisions, on scattering on the core and peripheral nucleons, and on the contribution of small wave-function components and their asymptotic behavior was determined. A comparison with available experimental data and with the results of calculations within different formalisms was performed.

  9. Study of neutron rich nuclei by delayed neutron decay using the Tonnerre multidetector

    International Nuclear Information System (INIS)

    Timis, C.N.

    2001-01-01

    A new detection array for beta delayed neutrons was built. It includes up to 32 plastic scintillation counters 180 cm long located at 120 cm from the target. Neutron energy spectra are measured by time-of-flight in the 300 keV-15 MeV range with good energy resolution. The device was tested with several known nuclei. Its performances are discussed in comparison with Monte Carlo simulations. They very high overall detection efficiency on the TONNERRE array made it possible to study one and two neutron emission of 11 Li. A complete decay scheme was obtained. The 33 Mg and 35 Al beta decays were investigated for the first time by neutron and gamma spectroscopy. Complete decay schemes were established and compared to large scale shell-model calculations. (authors)

  10. Coulomb excitation of neutron-rich nuclei between the N=40 and N=50 shell gaps using REX-ISOLDE and the Ge MINIBALL array

    CERN Multimedia

    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...

  11. Experimental study of high spin states in low-medium mass nuclei by use of charge particle induced reactions

    International Nuclear Information System (INIS)

    Alenius, N.G.

    1975-01-01

    For the test of nuclear models the study of the properties of nuclear states of high angular momentum is especially important, because such states can often be given very simple theoretical descriptions. High spin states are easily populated by use of reactions initiated by alpha particles or heavy ions. In this thesis a number of low-medium mass nuclei have been studied, with emphasis on high spin states. (Auth.)

  12. Investigation of neutron-rich rare-earth nuclei including the new isotopes 177Tm and 184Lu

    International Nuclear Information System (INIS)

    Rykaczewski, K.; Gippert, K.L.; Runte, E.; Schmidt-Ott, W.D.; Tidemand-Petersson, P.; Kurcewicz, W.; Nazarewicz, W.

    1989-01-01

    Decays of neutron-rich isotopes in the rare-earth region were studied by means of on-line mass separation and β-γ spectroscopy using multinucleon-transfer reactions between beams of 136 Xe (9 and 11.7 MeV/u), 186 W (11.7 and 15 MeV/u) and 238 U (11.4 MeV/u) and targets of nat W and Ta. The higher beam energies appear to be advantageous for the production of such isotopes. Two new isotopes were identified: 177 Tm with a half-life T 1/2 = 85±10/15 s, and 184 Lu with T 1/2 ≅ 18 s. A new 47 s-activity found at A = 171 is tentatively assigned to the decay of the new isotope 171 Ho. The properties of the ground and excited states of neutron-rich lanthanide isotopes are interpreted within the shell model using the deformed Woods-Saxon potential. A change of the ground-state configuration for odd-mass neutron-rich lutetium isotopes from π 7/2 + [404] to π 9/2 - [514] is suggested, this change being due to the influence of a large hexadecapole deformation. The role of a possible isometric state in 180 Lu for the nucleosynthesis of 180m Ta is discussed. (orig.)

  13. Ground state properties of exotic nuclei in deformed medium mass region

    International Nuclear Information System (INIS)

    Manju; Chatterjee, R.; Singh, Jagjit; Shubhchintak

    2017-01-01

    The dipole moment, size of the nucleus and other ground state properties of deformed nuclei 37 Mg and 31 Ne are presented. Furthermore with this deformed wave function the electric dipole strength distribution for deformed nuclei 37 Mg and 31 Ne is calculated. This will allow us to investigate the two dimensional scaling phenomenon with two parameters: quadrupole deformation and separation energy

  14. Landscape of α preformation probability for even–even nuclei in medium mass region

    Science.gov (United States)

    Qian, Yibin; Ren, Zhongzhou

    2018-03-01

    The behavior of α cluster preformation probability, in α decay, is a rich source of the structural information, such as the clustering, pairing, and shell evolution in heavy nuclei. Meanwhile, the experimental α decay data have been very recently compiled in the newest table NUBASE2016. Through a least square fit to the available experimental data of nuclear charge radii plus the neutron skin thickness, we obtain a new set of parameters for the two-parameter Fermi nucleon density distributions in target nuclei. Subsequently, we make use of these refreshed inputs, involved in the density-dependent cluster model, to extract α preformation factor ({P}α ) for a large range of medium α emitters with N pattern of P α in the open-shell region, the special attention has been paid to those exotic α-decaying nuclei around the Z = 50 and N = 82 shell closures. Moreover, the correlation between the α preformation factor and the microscopic correction of nuclear mass, corresponding to the effect of shell and pairing plus deformation, is in particular investigated, to pursue the valuable knowledge of the P α pattern over the nuclide chart. The feature of α preformation factor along with the neutron–proton asymmetry is then detected and discussed to some extent.

  15. Coulomb excitation of neutron-rich$^{28,29,30}$Na nuclei with MINIBALL at REX-ISOLDE: Mapping the borders of the island of inversion

    CERN Multimedia

    Butler, P; Cederkall, J A; Reiter, P; Wiens, A; Blazhev, A A; Kruecken, R; Voulot, D; Kalkuehler, M; Wadsworth, R; Gernhaeuser, R A; Hess, H E; Holler, A; Finke, F; Leske, J; Huyse, M L; Seidlitz, M

    We propose to study the properties of neutron-rich nuclei $^{28,29,30}$Na via Coulomb excitation experiments using the REX-ISOLDE facility coupled with the highly efficient MINIBALL array. Reliable B(E2,0$^{+}$ $\\rightarrow$ 2$^{+}$) values for $^{30,32}$Mg were obtained at ISOLDE. Together with recent new results on $^{31}$Mg, collective and single particle properties are probed for Z=12 at the N=20 neutron closed shell, the 'island of inversion'. We would like to extend this knowledge to the neighbouring $^{28,29,30}$Na isotopes where a different transition from the usual filling of the neutron levels into the region with low lying 2p-2h cross shell configurations is predicted by theory. Detailed theoretical predictions on the transition strength in all three Na nuclei are awaiting experimental verification and are the subject of this proposal. At REX beam energies of 3.0 MeV /nucleon the cross-sections for Coulomb excitation are sufficient. Moreover the results from the close-by $^{30,31,32}$Mg nuclei de...

  16. Synthesis and study of neutron-rich nuclides

    International Nuclear Information System (INIS)

    Luo Yixiao

    1995-01-01

    During the past few years our understanding of the decay properties and nuclear structure has been extended in a systematic fashion for the neutron-rich nuclei. This review will first sketch the production and identification of the neutron-rich nuclei throughout the whole mass region, and will then discuss the impressive progress in the studies of the exotic decay properties and nuclear structure of neutron-rich nuclei. Their astrophysical implications will also be outlined

  17. Spectroscopy of neutron rich nuclei using cold neutron induced fission of actinide targets at the ILL: The EXILL campaign

    Directory of Open Access Journals (Sweden)

    Blanc A.

    2013-12-01

    Full Text Available One way to explore exotic nuclei is to study their structure by performing γ-ray spectroscopy. At the ILL, we exploit a high neutron flux reactor to induce the cold fission of actinide targets. In this process, fission products that cannot be accessed using standard spontaneous fission sources are produced with a yield allowing their detailed study using high resolution γ-ray spectroscopy. This is what was pursued at the ILL with the EXILL (for EXOGAM at the ILL campaign. In the present work, the EXILL setup and performance will be presented.

  18. Energy-dependence of skin-mode fraction in E1 excitations of neutron-rich nuclei

    Directory of Open Access Journals (Sweden)

    Nakada H.

    2015-01-01

    Full Text Available We have extensively investigated characters of the low-energy E1 strengths in N > Z nuclei, by analyzing the transition densities obtained by the HF+RPA calculations with several effective interactions. Crossover behavior has been confirmed, from the skin mode at low energy to the pn mode at higher energy. Decomposing the E1 strengths into the skin-mode, pn-mode and interference fractions, we show that the ratio of the skin-mode strength to the full strength may be regarded as a generic function of the excitation energy, insensitive to nuclides and effective interactions, particularly beyond Ni.

  19. Microscopic description of the competition between spontaneous fission and α -decay in neutron-rich Ra, U and Pu nuclei

    International Nuclear Information System (INIS)

    Rodríguez-Guzmán, R; Robledo, L M

    2017-01-01

    Constrained mean-field calculations, based on the Gogny-D1M energy density functional, have been carried out to describe fission in Ra, U and Pu nuclei with neutron number 144 ≤ N ≤ 176. Fission paths, collective masses and zero-point quantum vibrational and rotational corrections are used to compute the spontaneous fission half-lives. We also pay attention to isomeric states along the considered fission paths. Alpha decay half-lives have also been computed using a parametrization of the Viola-Seaborg formula. Though there exists a strong variance of the predicted fission rates with respect to the details involved in their computation a robust trend is obtained indicating, that with increasing neutron number fission dominates over α -decay. Our results also suggest that a dynamical treatment of pairing correlations is required within the microscopic studies of the fission process in heavy nuclear systems. (paper)

  20. Investigation of correlations in light neutron-rich nuclei; Etude des correlations dans les noyaux legers riches en neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Normand, G

    2004-10-01

    Correlations play a crucial role in understanding the structure of light nuclei at and beyond the neutron drip-line. In this context, the two-neutron halo nucleus He{sup 6} and the unbound systems H{sup 5}, He{sup 7,9} and Li{sup 10} have been studied via measurements of the breakup of beams of He{sup 6} and Be{sup 11,12}. The CHARISSA and DEMON detector arrays were employed. The interpretation was facilitated by a simulation code (SILLAGE) which provided for the setup. In the case of He{sup 7}, the existence of an excited state with E{sub r} {approx} 1 MeV and gamma {approx} 0.75 MeV was confirmed. The virtual character of the s-wave ground state of Li{sup 10} was also confirmed and a scattering length of as {approx} -16 fm deduced. The results obtained for He{sup 9} suggest that a virtual s-wave state may exist just above threshold. The study of the three-body breakup of He{sup 6} found that the decay of the first 2+ state is essentially direct, while the decay of the remaining continuum strength is sequential - passage via He{sup 5}. Using the technique of intensity interferometry an rms separation between the halo neutrons of 7.7 +- 0.8 fm was derived. This result was confirmed by a complementary method utilizing Dalitz plots. In the case of H{sup 5}, the invariant mass spectrum was found to exhibit a broad (gamma {approx} 2 MeV) structure some 1.8 MeV above threshold. Comparison with recent three-body model calculations suggest that this corresponds to the predicted 1/2+ ground state. An rms valence neutron separation of some 5.5 fm was estimated. A search was also carried out for the 4n system using the Be{sup 12*} (2 alpha + Xn decay channel). No signal was observed beyond that expected on the basis of the known background processes. (author)

  1. Study of neutron-rich Mo isotopes by the projected shell model ...

    Indian Academy of Sciences (India)

    also predicts a decrease in the quantum of triaxiality with increasing neutron number and angular momentum for odd mass neutron-rich Mo isotopes. Keywords. Neutron-rich nuclei; electromagnetic quantities; projected shell model. PACS Nos 21.60.Cs; 21.10.Ky; 21.10.Re; 27.60.+j. 1. Introduction. Neutron-rich nuclei in the ...

  2. Experiments with neutron-rich isomeric beams

    International Nuclear Information System (INIS)

    Rykaczewski, K.; Lewitowicz, M.; Pfuetzner, M.

    1998-01-01

    A review of experimental results obtained on microsecond-isomeric states in neutron-rich nuclei produced in fragmentation reactions and studied with SISSI-Alpha-LISE3 spectrometer system at GANIL Caen is given. The perspectives of experiments based on secondary reactions with isomeric beams are presented

  3. Mass measurement project by determination of Q{sub {beta}} for neutron-rich nuclei; Projet de mesure des masses par determination des Q{sub {beta}} pour des noyaux tres riches en neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Pautrat, M.; Lagrange, J.M.; Petizon, L. [Paris-11 Univ., 91 - Orsay (France). Inst. de Physique Nucleaire; Vanhorenbeeck, J.; Duhamel, P. [Brussels Univ. (Belgium). Inst. d`Astronomie et d`Astrophysique; Binon, F. [Universite Libre de Bruxelles (Belgium)

    1993-12-31

    The aim of the project described hereafter is to collect new data on the exotic neutron rich nuclei of the Fe to Zn region, and in particular to determine their masses, for both nuclear physics and astrophysics purposes. These isotopes will be produced through projectile fragmentation at the GANIL facility and selected by the LISE3 spectrometer. Their half-lives will be measured as well as the energy of their main {gamma} rays; {gamma} - {gamma} coincidences will then allow to build a preliminary level scheme. The analysis of {beta} spectra and {beta} - {gamma} coincidences will finally provide the maximum {beta} decay energies of the studied nuclei leading to their masses. The difficulties arising from the low production rates, the {beta} detection, the data handling are discussed together with the solutions proposed to overcome them. (authors). 17 refs.

  4. Measurement of ground state properties of neutron-rich nuclei on the r-process path between the N=50 and N=82 shells

    CERN Multimedia

    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...

  5. Neutron-rich isotopes of the lightest elements

    International Nuclear Information System (INIS)

    Oganesyan, Yu.Ts.; Penionzhkevich, Yu.Eh.; Kalpakchieva, R.

    1989-01-01

    A review is presented of the experimental investigations on the stability of very neutron-rich light nuclei carried out at the JINR Laboratory of Nuclear Reactions. Results on mass excess measurements are reported for 4 H, 5 H, 6 H, 7 H and for the superheavy helium isotope 9 He. Some results from the joint JINR-Ganil experiment on the search for and study of new neutron-rich light nuclei are also given. Analyzed are new possibilities for the investigation of multineutron decay of light nuclei. 14 refs.; 10 figs

  6. Synthesis and study of neutron-rich nuclides

    International Nuclear Information System (INIS)

    Luo, Y.X.

    1995-01-01

    During the past few years our understanding of the decay properties and nuclear structure has been extended in a systematic fashion for the neutron-rich nuclei. This review will discuss the impressive progress in the studies of the exotic decay properties and nuclear structure of n-rich nuclei. Their astrophysical implications will also be outlined. ((orig.))

  7. Proton reaction cross-section measurements on stable and neutron-rich nuclei a s probe of the nucleon-nucleus interaction

    Czech Academy of Sciences Publication Activity Database

    de Vismes, A.; Roussel-Chomaz, P.; Mittig, W.; Pakou, A.; Alamanos, N.; Angélique, J. C.; Auger, F.; Barrette, J.; Bauge, E.; Belozyrov, A. V.; Dlouhý, Zdeněk

    2002-01-01

    Roč. 706, - (2002), s. 295-312 ISSN 0375-9474 R&D Projects: GA AV ČR IAA1048102 Keywords : optical-mode analysis * elastic-scattering * inelastic-scattering * isospin dependence * finite nuclei * isotopes * consistent * radii * approximation * potentials Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 1.568, year: 2002

  8. Total reaction cross sections and neutron-removal cross sections of neutron-rich light nuclei measured by the COMBAS fragment-separator

    Science.gov (United States)

    Hue, B. M.; Isataev, T.; Erdemchimeg, B.; Artukh, A. G.; Aznabaev, D.; Davaa, S.; Klygin, S. A.; Kononenko, G. A.; Khuukhenkhuu, G.; Kuterbekov, K.; Lukyanov, S. M.; Mikhailova, T. I.; Maslov, V. A.; Mendibaev, K.; Sereda, Yu M.; Penionzhkevich, Yu E.; Vorontsov, A. N.

    2017-12-01

    Preliminary results of measurements of the total reaction cross sections σR and neutron removal cross section σ-xn for weakly bound 6He, 8Li, 9Be and 10Be nuclei at energy range (20-35) A MeV with 28Si target is presented. The secondary beams of light nuclei were produced by bombardment of the 22Ne (35 A MeV) primary beam on Be target and separated by COMBAS fragment-separator. In dispersive focal plane a horizontal slit defined the momentum acceptance as 1% and a wedge degrader of 200 μm Al was installed. The Bρ of the second section of the fragment-separator was adjusted for measurements in energy range (20-35) A MeV. Two-neutron removal cross sections for 6He and 10Be and one -neutron removal cross sections 8Li and 9Be were measured.

  9. Neutron-rich nuclei produced at zero degrees in damped collisions induced by a beam of 18O on a 238U target

    Science.gov (United States)

    Stefan, I.; Fornal, B.; Leoni, S.; Azaiez, F.; Portail, C.; Thomas, J. C.; Karpov, A. V.; Ackermann, D.; Bednarczyk, P.; Blumenfeld, Y.; Calinescu, S.; Chbihi, A.; Ciemala, M.; Cieplicka-Oryńczak, N.; Crespi, F. C. L.; Franchoo, S.; Hammache, F.; Iskra, Ł. W.; Jacquot, B.; Janssens, R. V. F.; Kamalou, O.; Lauritsen, T.; Lewitowicz, M.; Olivier, L.; Lukyanov, S. M.; Maccormick, M.; Maj, A.; Marini, P.; Matea, I.; Naumenko, M. A.; de Oliveira Santos, F.; Petrone, C.; Penionzhkevich, Yu. E.; Rotaru, F.; Savajols, H.; Sorlin, O.; Stanoiu, M.; Szpak, B.; Tarasov, O. B.; Verney, D.

    2018-04-01

    Cross sections and corresponding momentum distributions have been measured for the first time at zero degrees for the exotic nuclei obtained from a beam of 18O at 8.5 MeV/A impinging on a 1 mg/cm2238U target. Sizable cross sections were found for the production of exotic species arising from the neutron transfer and proton removal from the projectile. Comparisons of experimental results with calculations based on deep-inelastic reaction models, taking into account the particle evaporation process, indicate that zero degree is a scattering angle at which the differential reaction cross section for production of exotic nuclei is at its maximum. This result is important in view of the new generation of zero degrees spectrometers under construction, such as the S3 separator at GANIL, for example.

  10. {gamma} ray spectroscopy of neutron rich nuclei around N=20; Spectroscopie {gamma} des noyaux riches en neutrons autour de N=20

    Energy Technology Data Exchange (ETDEWEB)

    Gelin, M

    2007-09-15

    There is an island of inversion around {sup 32}Mg (12 protons, 20 neutrons) in contradiction with a shell closure N=20. It means a coexistence of spherical and deformed shapes. This work is devoted to the study of {gamma}-ray spectroscopy for nuclei in this region, based on an experiment done at GANIL with a composite secondary beam produced by fragmentation. The originality of the method used here lies in the possibility to study simultaneously several nuclei, and for each of them to explore several reaction channels. The VAMOS spectrometer was used for the identification of the ejectiles. The {gamma}-rays were detected with EXOGAM, a germanium clover array. The detectors used before and after the target allowed for a unique identification and a selection of the reaction channel: inelastic scattering, transfer and fragmentation reaction. In this thesis the following nuclei were studied: {sup 28}Ne, {sup 30-32}Mg {sup 31-34}Al, {sup 33-35}Si, {sup 35}P. New {gamma}-rays have been observed. The {gamma}-ray angular distributions and {gamma}-{gamma} angular correlations have been measured for some transitions. Assignment of spins and parities has been proposed for some states. In particular, in {sup 34}Si, the 3{sup -} assignment is confirmed and a new candidate for the second 0{sup +} has been proposed. In {sup 32}Mg, the state at 2.321 MeV, for which conflicting assignment existed, is deduced from the present data as a 4{sup +}, and a 6{sup +} state is proposed. (author)

  11. Measurement of beta decay energies of short-lived neutron rich atomic nuclei in the mass range 101 ≤ A ≤ 106 and A=109

    International Nuclear Information System (INIS)

    Weikard, H.

    1986-01-01

    At the mass separator LOHENGRIN of the Laue-Langevin institute in Grenoble for 18 nuclei (Zr, Nb, Mo, Tc, Ru, and Rh nuclides) with masses 101 ≤ A ≤ 106 and A=109 Q β values were determined from measurement of beta decay energies. From the study of the isomerism in 102 Nb resulted that the energetic distance of the two isomers is certainly smaller than 200 keV, that it is probably even smaller than 100 keV. The decay scheme for 102 Nb could be extended by one level which is depopulated by two gamma lines. For the decay of the 109 Ru the approach of a decay scheme is given: Five new levels are proposed. The diagrams of the two-particle separation energies which could be extended in this thesis confirm the continuation of the deformation in the considered region. A deformed subshell at N=62 however cannot yet be clearly detected. (orig./HSI) [de

  12. Coupled-cluster computations of atomic nuclei.

    Science.gov (United States)

    Hagen, G; Papenbrock, T; Hjorth-Jensen, M; Dean, D J

    2014-09-01

    In the past decade, coupled-cluster theory has seen a renaissance in nuclear physics, with computations of neutron-rich and medium-mass nuclei. The method is efficient for nuclei with product-state references, and it describes many aspects of weakly bound and unbound nuclei. This report reviews the technical and conceptual developments of this method in nuclear physics, and the results of coupled-cluster calculations for nucleonic matter, and for exotic isotopes of helium, oxygen, calcium, and some of their neighbors.

  13. Fission decay properties of ultra neutron-rich uranium isotopes

    Indian Academy of Sciences (India)

    Abstract. The fission decay of highly neutron-rich uranium isotopes is investigated which shows interesting new features in the barrier properties and neutron emission char- acteristics in the fission process. 233U and 235U are the nuclei in the actinide region in the beta stability valley which are thermally fissile and have ...

  14. Systematic study of neutron-rich Molybdenum isotopes

    International Nuclear Information System (INIS)

    Oudih, M.R.; Fellah, M.; Allal, N.H.; Benhamouda, N.

    2010-01-01

    The ground state properties of neutron-rich even-even Molybdenum isotopes are studied using Hartree-Fock-Bogoliubov mean-field theory. Quantities such as two-neutron separation energies and r.m.s radii have been investigated and compared with available experimental data. Deformations and shape coexistence for not yet observed nuclei are predicted.

  15. Low energy resonance in the neutron rich nucleus of 48Ca. New detectors for the study of unstable nuclei: MUST and CATS

    International Nuclear Information System (INIS)

    Ottini, St.

    1998-01-01

    Two new detectors have been developed to study reactions resulting from exotic beams. The first one, MUST, a set of Si strip detectors is devoted to light recoil particles detection between 500 eV and 120 MeV. The 40 Ar elastic and inelastic scattering analysis at 77 MeV per nucleon showed a non ambiguous identification of the particles in the detector, thanks the time and energy resolutions. The second one, CATs, is a set of beam detectors. These low pressure wire chambers allow each particle measurement of the exotic beams with an accuracy of 0,4 mm. A special interest is given to the halo nuclei low excitation energy spectra. A dipolar low energy resonance should be observed. The inelastic scattering at 60 MeV per nucleon on two targets ( 40 Ca and 48 Ca) has been studied with SPEG at Ganil (France), to search a low energy resonance. It is not possible to conclude on this low energy resonance existence. (A.L.B.)

  16. Neutron-capture reactions by stable and unstable neutron-rich nuclei and their relevance for nucleosynthesis in hot and explosive astrophysical scenarios

    International Nuclear Information System (INIS)

    Hofinger, R.

    1997-10-01

    This thesis deals on the one hand with neutron-capture reactions by carbon-, nitrogen-, oxygen- and sulfur-isotopes, and on the other hand with the two-step processes 4 He(2n, γ) 6 He and 9 Li(2n, γ) 11 Li. Some of the involved carbon-, nitrogen- and oxygen-isotopes possess neutron-halos characterized by the unexpected large radial extension of the nuclear matter density distribution. Special attention is paid to the halo properties in the calculation of the direct neutron capture cross section. For the determination of the nuclear structure, models are used, when no experimental information is available. The results for the reaction rates are compared to previously used rates. The rates obtained in this work are partly orders of magnitude higher than the previously used reaction rates. The reaction rates for the two-step processes are on the one hand calculated assuming a two-step process, on the other hand from genuine three-body models for the process of photodisintegration of the nuclei 6 He and 11 Li. It turns out that the calculations assuming a trio-step process underestimate the reaction rates by orders of magnitude. The influence of the reaction rate for the reaction 4 He(2n, γ) 6 He and the formation of 12 C is examined in a nuclear reaction network under conditions which are typical for the α- process in supernovae of type II. It turns out that under these conditions the influence of the reaction 4 He(2n, γ) 6 He is negligible on the formation of 12 C. (author)

  17. Observation of the new neutron-rich nuclei 29F, 35,36Mg, 38,39Al, 40,41Si, 43,44P, 45,46,47S, 46,47,48,49Cl and 49,50,51Ar by means of a 55 MeV/u 48Ca beam

    International Nuclear Information System (INIS)

    Guillemaud-Mueller, D.; Anne, R.; Penionzhkevich, Yu.Eh.

    1988-01-01

    Using magnetic separation and identification through time of flight and ΔE,E measurements, the new neutron-rich nuclei, 29 F, 35,36 Mg, 38,39 Al, 40,41 Si, 43,44 P, 45,46,47 S, 46,47,48,49 Cl, 49,50,51 Ar have been observed from interactions of 48 Ca beam of 55 MeV/u with tantalum targets

  18. Decay analysis of compound nuclei formed in reactions with exotic neutron-rich 9Li projectile and the synthesis of 217At* within the dynamical cluster-decay model

    Science.gov (United States)

    Kaur, Arshdeep; Kaushal, Pooja; Hemdeep; Gupta, Raj K.

    2018-01-01

    The decay of various compound nuclei formed via exotic neutron-rich 9Li projectile is studied within the dynamical cluster-decay model (DCM). Following the earlier work of one of us (RKG) and collaborators (M. Kaur et al. (2015) [1]), for an empirically fixed neck-length parameter ΔRemp, the only parameter in the DCM, at a given incident laboratory energy ELab, we are able to fit almost exactly the (total) fusion cross section σfus =∑x=16σxn for 9Li projectile on 208Pb and other targets, with σfus depending strongly on the target mass of the most abundant isotope and its (magic) shell structure. This result shows the predictable nature of the DCM. The neck-length parameter ΔRemp is fixed empirically for the decay of 217At* formed in 9Li + 208Pb reaction at a fixed laboratory energy ELab, and then the total fusion cross section σfus calculated for all other reactions using 9Li as a projectile on different targets. Apparently, this procedure could be used to predict σfus for 9Li-induced reactions where experimental data are not available. Furthermore, optimum choice of "cold" target-projectile combinations, forming "hot" compact configurations, are predicted for the synthesis of compound nucleus 217At* with 8Li + 209Pb as one of the target-projectile combination, or another (t , p) combination 48Ca + 169Tb, with a doubly magic 48Ca, as the best possibility.

  19. Multi-Messenger Observations of Neutron Rich Matter

    Energy Technology Data Exchange (ETDEWEB)

    Horowitz, C. J. [UTK/ORNL/Indiana University

    2012-01-01

    At very high densities, electrons react with protons to form neutron rich matter. This material is central to many fundamental questions in nuclear physics and astrophysics. Moreover, neutron rich matter is being studied with an extraordinary variety of new tools such as the Facility for Rare Isotope Beams (FRIB) and the Laser Interferometer Gravitational Wave Observatory (LIGO). We describe the Lead Radius Experiment (PREX) that uses parity violating electron scattering to measure the neutron radius in 208Pb. This has important implications for neutron stars and their crusts. We discuss X-ray observations of neutron star radii. These also have important implications for neutron rich matter. Gravitational waves (GW) open a new window on neutron rich matter. They come from sources such as neutron star mergers, rotating neutron star mountains, and collective r-mode oscillations. Using large scale molecular dynamics simulations, we find neutron star crust to be very strong. It can support mountains on rotating neutron stars large enough to generate detectable gravitational waves. We believe that combing astronomical observations using photons, GW, and neutrinos, with laboratory experiments on nuclei, heavy ion collisions, and radioactive beams will fundamentally advance our knowledge of compact objects in the heavens, the dense phases of QCD, the origin of the elements, and of neutron rich matter.

  20. The neutrino opacity of neutron rich matter

    Science.gov (United States)

    Alcain, P. N.; Dorso, C. O.

    2017-05-01

    The study of neutron rich matter, present in neutron star, proto-neutron stars and core-collapse supernovae, can lead to further understanding of the behavior of nuclear matter in highly asymmetric nuclei. Heterogeneous structures are expected to exist in these systems, often referred to as nuclear pasta. We have carried out a systematic study of neutrino opacity for different thermodynamic conditions in order to assess the impact that the structure has on it. We studied the dynamics of the neutrino opacity of the heterogeneous matter at different thermodynamic conditions with semiclassical molecular dynamics model already used to study nuclear multifragmentation. For different densities, proton fractions and temperature, we calculate the very long range opacity and the cluster distribution. The neutrino opacity is of crucial importance for the evolution of the core-collapse supernovae and the neutrino scattering.

  1. The neutrino opacity of neutron rich matter

    Energy Technology Data Exchange (ETDEWEB)

    Alcain, P.N., E-mail: pabloalcain@gmail.com [Departamento de Física, FCEyN, UBA and IFIBA, Conicet, Pabellón 1, Ciudad Universitaria, 1428 Buenos Aires (Argentina); IFIBA-CONICET (Argentina); Dorso, C.O. [Departamento de Física, FCEyN, UBA and IFIBA, Conicet, Pabellón 1, Ciudad Universitaria, 1428 Buenos Aires (Argentina); IFIBA-CONICET (Argentina)

    2017-05-15

    The study of neutron rich matter, present in neutron star, proto-neutron stars and core-collapse supernovae, can lead to further understanding of the behavior of nuclear matter in highly asymmetric nuclei. Heterogeneous structures are expected to exist in these systems, often referred to as nuclear pasta. We have carried out a systematic study of neutrino opacity for different thermodynamic conditions in order to assess the impact that the structure has on it. We studied the dynamics of the neutrino opacity of the heterogeneous matter at different thermodynamic conditions with semiclassical molecular dynamics model already used to study nuclear multifragmentation. For different densities, proton fractions and temperature, we calculate the very long range opacity and the cluster distribution. The neutrino opacity is of crucial importance for the evolution of the core-collapse supernovae and the neutrino scattering.

  2. Neutron-rich B isotopes studied with antisymmetrized molecular dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Kanada-En`yo, Y.; Horiuchi, H. [Department of Physics, Kyoto University, Kyoto 606-01 (Japan)

    1995-08-01

    Structure of odd-even B isotopes up to the neutron dripline is studied systematically with the antisymmetrized molecular dynamics (AMD). The AMD method has already proved to be a powerful theoretical approach for the systematic study of nuclear structure in extensive region including exotic neutron-rich nuclei as well as ordinary nuclei. It is owing to its flexible nature free from any model assumptions such as the existence of clusters. The energies and other observed data of B isotopes are reproduced well. Especially very good reproduction of electromagnetic properties is obtained. The systematic behavior of the electromagnetic properties is explained in relation to the drastic change between clustering structure and shell-model-like structure. This explanation gives us an important indication that clustering structure in neutron-rich B nuclei is strongly suggested by the experimental data. It is shown that the structure change with increase of the neutron number is largely governed by the shell effect of neutron orbits. Exotic structure with new type of clustering is suggested to evolve in neutron-rich nuclei near the dripline.

  3. Systematic study of electric-dipole excitations with fully self-consistent Skyrme HF plus RPA from light-to-medium-mass deformed nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Inakura, T. [University of Tsukuba, Institute for Physics, Tsukuba (Japan); Nakatsukasa, T. [RIKEN Nishina Center, Theoretical Nuclear Physics Laboratory, Wako (Japan); Yabana, K. [University of Tsukuba, Institute for Physics, Tsukuba (Japan); University of Tsukuba, Center for Computational Sciences, Tsukuba (Japan)

    2009-12-15

    We undertake a systematic calculation on electric-dipole responses of even-even nuclei for a wide mass region employing a fully self-consistent Hartree-Fock plus RPA approach. For an easy implementation of the fully self-consistent calculation, the finite-amplitude method which we have proposed recently is employed. We calculated dipole responses in Cartesian mesh representation, which can deal with deformed nuclei but do not include pairing correlation. The systematic calculation has reached Nickel isotopes. The calculated results show reasonable agreement for heavy nuclei while the average excitation energies are underestimated for light nuclei. We show a systematic comparison of the splitting of the peak energy with the ground-state deformation. (orig.)

  4. Nucleon effective masses in neutron-rich matter

    Science.gov (United States)

    Li, Bao-An; Cai, Bao-Jun; Chen, Lie-Wen; Xu, Jun

    2018-03-01

    Various kinds of isovector nucleon effective masses are used in the literature to characterize the momentum/energy dependence of the nucleon symmetry potential or self-energy due to the space/time non-locality of the underlying isovector strong interaction in neutron-rich nucleonic matter. The multifaceted studies on nucleon isovector effective masses are multi-disciplinary in nature. Besides structures, masses and low-lying excited states of nuclei as well as nuclear reactions, studies of the isospin dependence of short-range correlations in nuclei from scatterings of high-energy electrons and protons on heavy nuclei also help understand nucleon effective masses especially the so-called E-mass in neutron-rich matter. A thorough understanding of all kinds of nucleon effective masses has multiple impacts on many interesting issues in both nuclear physics and astrophysics. Indeed, essentially all microscopic many-body theories and phenomenological models with various nuclear forces available in the literature have been used to calculate single-nucleon potentials and the associated nucleon effective masses in neutron-rich matter. There are also fundamental principles connecting different aspects and impacts of isovector strong interactions. In particular, the Hugenholtz-Van Hove theorem connects analytically nuclear symmetry energy with both isoscalar and isovector nucleon effective masses as well as their own momentum dependences. It also reveals how the isospin-quartic term in the equation of state of neutron-rich matter depends on the high-order momentum-derivatives of both isoscalar and isovector nucleon potentials. The Migdal-Luttinger theorem facilitates the extraction of nucleon E-mass and its isospin dependence from experimentally constrained single-nucleon momentum distributions. The momentum/energy dependence of the symmetry potential and the corresponding neutron-proton effective mass splitting also affect transport properties and the liquid-gas phase

  5. Experimental study of neutron-skin thicknesses in neutron-rich isotopes

    CERN Document Server

    Krasznahorkay, A; Gulyás, J; Adrich, P; Aumann, T; Datta-Pramanik, U; Emling, H; Nociforo, C; Rudrajyoti, P; Simon, H

    2003-01-01

    The difference between the neutron and proton radii of a heavy stable nucleus is of the order of a few percent. The precise knowledge of the symmetry energy is essential not only for describing the structure of neutron-rich nuclei, but also for describing the properties of the neutron-rich matter in nuclear astrophysics. A new tool was introduced for studying the neutron-skin thickness, by exciting the spin-dipole resonance (SDR). (R.P.)

  6. Hot nuclei production and deexcitation in heavy ions induced reactions on medium mass targets in the 10-84 MeV/nucleon energy domain

    International Nuclear Information System (INIS)

    Lleres, A.

    1988-01-01

    Velocity, angular distributions and total cross sections for heavy residues produced in the reactions 12 C, 14 N, 20 Ne, 40 Ar + 124 Sn have been measured in the 10-84 MeV/nucleon incident energy range using catchers technique in association with off-line gamma-activity spectroscopy. The observed reaction products are interpreted as evaporation residues from equilibrated systems formed by complete or incomplete fusion of the projectile and target nuclei. From the velocities and residual masses measured at forward angles, the linear momentum transfers and excitation energies associated with the intermediate systems are estimated using simple fusion-evaporation models and are next compared to the predictions of the preequilibrium and Fermi jets models. Energy, angular, charge and charge correlation distributions for intermediate mass fragments emitted in the reaction 32 S + nat Ag at 30 MeV/nucleon were also measured using gaseous and silicon detectors. The energy and angular distributions indicate that both equilibrated and non-equilibrated emitting sources are present. The equilibrium emission is attributed to the deexcitation of systems produced by incomplete fusion of the projectile and target nuclei. The charge correlation distributions are consistent with an asymmetric fission decay process. The linear momentum transfer and excitation energy associated with the equilibrated source are estimated using a simple fusion-fission model [fr

  7. New Isomers in the Neutron-Rich Region Beyond 208Pb

    Directory of Open Access Journals (Sweden)

    Gottardo A.

    2014-03-01

    Full Text Available The region of neutron-rich nuclei beyond 208Pb has been very difficult to explore due to its high mass and exoticity. However, recent experimental improvements allowed one to perform a quite extended isomer decay spectroscopy of these nuclei.

  8. 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)

  9. Gamma-ray spectroscopy of the neutron-rich Ni region through heavy-ion deep-inelastic collisions

    International Nuclear Information System (INIS)

    Ishii, T.; Asai, M.; Matsuda, M.; Ichikawa, S.; Makishima, A.; Hossain, I.; Kleinheinz, P.; Ogawa, M.

    2002-01-01

    Nuclei in the neutron-rich Ni region have been studied by γ-ray spectroscopy. Gamma-rays emitted from isomers, with T 1/2 >1 ns, produced in heavy-ion deep-inelastic collisions were measured with an isomer-scope. The nuclear structure of the doubly magic 68 Ni and its neighbor 69,71 Cu is discussed on the basis of the shell model. Future experiments for more neutron-rich Ni nuclei are also viewed. (orig.)

  10. Gamma-ray spectroscopy of the neutron-rich Ni region through heavy-ion deep-inelastic collisions

    Science.gov (United States)

    Ishii, T.; Asai, M.; Makishima, A.; Hossain, I.; Kleinheinz, P.; Ogawa, M.; Matsuda, M.; Ichikawa, S.

    Nuclei in the neutron-rich Ni region have been studied by γ-ray spectroscopy. Gamma-rays emitted from isomers, with T1/2 > 1 ns, produced in heavy-ion deep-inelastic collisions were measured with an isomer-scope. The nuclear structure of the doubly magic 68Ni and its neighbor 69,71Cu is discussed on the basis of the shell model. Future experiments for more neutron-rich Ni nuclei are also viewed.

  11. Laser Spectroscopy Studies in the Neutron-Rich Sn Region

    CERN Multimedia

    Obert, J

    2002-01-01

    We propose to use the powerful laser spectroscopy method to determine the magnetic moment $\\mu$ and the variation of the mean square charge radius ($\\delta\\,\\langle$r$_{c}^{2}\\,\\rangle$) for ground and long-lived isomeric states of the Sn isotopes from A=125 to the doubly-magic $^{132}$Sn isotope and beyond. For these neutron-rich Sn nuclei, numerous $\\delta\\,\\langle$r$^{2}_{c}\\,\\rangle$ curves have already been calculated and the predictions depend upon the effective interactions used. Therefore, a study of the effect of the shell closure N=82 on the $\\delta\\,\\langle$r$^{2}_{c}\\,\\rangle$ values in the Z=50 magic nuclei is of great interest, especially because $^{132}$Sn is located far from the stability valley. It will help to improve the parameters of the effective interactions and make them more suitable to predict the properties of exotic nuclei. \\\\ \\\\The neutron-rich Sn isotopes produced with an uranium carbide target, are ionized using either a hot plasma ion source or the resonant ionization laser ion ...

  12. Reaction cross section measurements of neutron-rich exotic nuclei in the vicinity of closed shells N=20 and N=28; Mesures de section efficace de reaction de noyaux exotiques riches en neutrons dans la zone de fermeture des couches N=20 et N=28

    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)

  13. Examination of different strengths of octupole correlations in neutron-rich Pr and Pm isotopes

    Czech Academy of Sciences Publication Activity Database

    Thiamova, G.; Alexa, P.; Hons, Zdeněk; Simpson, G.S.

    2012-01-01

    Roč. 86, č. 4 (2012), 044334/1-044334/5 ISSN 0556-2813 R&D Projects: GA ČR GAP203/10/0310 Institutional support: RVO:61389005 Keywords : neutron rich nuclei * octupole correlations Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 3.715, year: 2012

  14. N=14 and 16 shell gaps in neutron-rich oxygen isotopes

    Czech Academy of Sciences Publication Activity Database

    Stanoiu, M.; Azaiez, F.; Dombrádi, Zs.; Sorlin, O.; Brown, A.; Belleguic, M.; Sohler, D.; Saint Laurent, M. G.; Lopez-Jimenez, M. J.; Penionzhkevich, Y. E.; Sletten, G.; Achouri, N. L.; Angélique, J. C.; Becker, F.; Borcea, C.; Bourgeois, C.; Bracco, A.; Daugas, J. M.; Dlouhý, Zdeněk; Donzaud, C.; Duprat, J.; Fülöp, Zs.; Guillemaud-Mueller, D.; Grévy, S.; Ibrahim, F.; Kerek, A.; Krasznahorkay, A.; Lewitowicz, M.; Leenhardt, S.; Lukyanov, S.; Mayet, P.; Mandal, S.; van der Marel, H.; Mittig, W.; Mrázek, Jaromír; Negoita, F.; de Oliveira Santos, F.; Podolyák, Zs.; Pouhgeon, F.; Porquet, M. G.; Roussel-Chomaz, P.; Savajols, H.; Sobolev, Y.; Stodel, C.; Timár, J.; Yamamoto, A.

    -, č. 69 (2004), 034312 ISSN 0556-2813 R&D Projects: GA AV ČR IAA1048102 Institutional research plan: CEZ:AV0Z1048901 Keywords : shell gaps * neutron-rich nuclei * oxygen isotopes Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 3.125, year: 2004

  15. K isomerism and collectivity in neutron-rich rare-earth isotopes.

    OpenAIRE

    Patel, Zena

    2016-01-01

    Neutron-rich rare-earth isotopes were produced by in-flight fission of 238U ions at the Radioactive Isotope Beam Factory (RIBF), RIKEN, Japan. In-flight fission of a heavy, high-intensity beam of 238U ions on a light target provides the cleanest secondary beams of neutron-rich nuclei in the rare-earth region of isotopes. In-flight fission is advantageous over other methods of nuclear production, as it allows for a secondary beam to be extracted, from which the beam species can be separated an...

  16. Study of shape evolution and electromagnetic properties in neutron-rich Zr and Sr isotopes

    Science.gov (United States)

    Chaudhary, R.; Devi, R.; Khosa, S. K.

    2018-03-01

    The projected shell model calculations have been carried out in neutron-rich 100-108Zr and 98-102Sr isotopes. The shape evolution and electromagnetic properties have been examined in neutron-rich Zr and Sr isotopes around N = 60. The structure of yrast states, backbending phenomena, g-factors and B( E2) transition probabilities are calculated and compared with corresponding observable quantities. The present calculations predict the occurrence of coexistence of prolate-oblate shapes at 0+ state in 100,102Zr and 98,100Sr. Nuclei beyond N = 62 are predicted to have prolate deformation in the ground-state.

  17. In-beam gamma-ray spectroscopy of neutron-rich nuclei using fragmentation of radioactive beams and half-lives measurements of excited levels in nuclei closed to {sup 68}Ni; Spectroscopie {gamma} en ligne de noyaux legers riches en neutrons produits par fragmentation de faisceau radioactif et mesures de temps de vie des niveaux excites dans des noyaux proches de {sup 68}Ni

    Energy Technology Data Exchange (ETDEWEB)

    Stanoiu, M.A

    2003-01-01

    This thesis deals with studies of nuclei far from the valley of stability produced at GANIL by projectile fragmentation at intermediate energies. It consists of two parts. The first one is dedicated to the study of very light exotic nuclei around N=14. This is the first time that online {gamma}-ray spectroscopy combined with the projectile fragmentation was used with radioactive incident beams at GANIL. The advantages and the limitations of this method were established. 40 different nuclei have been produced and studied at the same time. A strong dependence of the population of excited states on the type of projectile was observed. New information was obtained on the structure of the isotopes B{sup 14,15}, C{sup 17,18,19,20}, N{sup 18,19,20,21,22}, O{sup 22,23,24}, F{sup 24,25,26} and Ne{sup 29}. The level schemes obtained from this study have been compared with shell-model predictions. In particular, the energy of 1588(20) keV found for the first 2{sup +} excited state in C{sup 20}, as well as the non-existence of a bound state in O{sup 24}, show that the proton-neutron interaction plays an important role in the structure of these nuclei. In the second part, an experiment is presented concerning the neutron-rich isomer nuclei around Ni{sup 68} produced by the LISE spectrometer. The fast-timing method was applied for the first time for the study of nuclei produced by projectile fragmentation. Subnanosecond half-lives of several levels in Ni{sup 67,69,90} and Cu{sup 71,72} were measured simultaneously and with high precision. These results have allowed us to test the shell model predictions for several E2 transitions and their associated B(E2) transition probabilities. (author)

  18. Beta decay and magnetic moments as tools to probe nuclear structure. Study of neutron-rich nuclei around N=40; Decroissance beta et moments magnetiques comme outils pour sonder la structure nucleaire. Etude des noyaux riches en neutrons autour de N=40

    Energy Technology Data Exchange (ETDEWEB)

    Matea, I

    2003-12-01

    The evolution of nuclear structure in nuclei far from the {beta} stability line is one of the 'hot topics' in modern experimental and theoretical nuclear physics. The present thesis is devoted to the study of structure of neutron-rich nuclei around N=40. The evolution of the neutron g9/2 orbital with increasing number of neutrons is one of the key points defining the structure of these nuclei at low excitation energy. We used for this investigation as experimental tools the magnetic dipole moments measurements and the {beta} decay spectroscopy. For the measurement of the gyromagnetic factor of the 9/2{sup +} isomeric state in Fe{sup 61} we have applied the TDPAD method. This method (like most of measurements of nuclear moments) requires an oriented ensemble of nuclei. The orientation of Fe{sup 61m} was achieved via the fragmentation of Ni{sup 64} at 55 MeV/u and the selection of the fragment momentum with the LISE spectrometer at GANIL. The experimental device was specially conceived to preserve the alignment up to the implantation point. The measured value of the g factor was compared with large-scale shell model and Hartree-Fock-Bogoliubov model predictions. The nuclei studied via {beta} decay were produced by the fragmentation of Kr{sup 86} at 58 MeV/u. For the selection of reaction products we used for the first time the LISE2000 spectrometer and for the detection of {gamma} rays four EXOGAM clover detectors. We measured 5 new lifetimes and 4 lifetimes with a higher precision. From the prompt {beta}{gamma} coincidences we identified new states in the daughter nuclei, as it is the case of the first 2{sup +} excited states in Fe{sup 68} and Ni{sup 72}. The results were compared with the predictions of the large-scale shell model. Other transitions were observed for the first time in {beta}{gamma} decay of Ti{sup 60}, Fe{sup 70} and Co{sup 71,73}. (author)

  19. Study of the N=28 shell closure by one neutron transfer reaction: astrophysical application and {beta}-{gamma} spectroscopy of neutron rich nuclei around N=32/34 and N=40; Etude de la fermeture de couche N=28 autour du noyau {sub 18}{sup 46}Ar{sub 28} par reaction de transfert d'un neutron: application a l'astrophysique et Spectroscopie {beta}-{gamma} de noyaux riches en neutrons de N=32/34 et N=40

    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)

  20. Study of neutron rich nuclei by delayed neutron decay using the Tonnerre multidetector; Etude de la decroissance par neutrons retardes de noyaux legers riches en neutrons avec le multidetecteur tonnerre

    Energy Technology Data Exchange (ETDEWEB)

    Timis, C.N

    2001-07-01

    A new detection array for beta delayed neutrons was built. It includes up to 32 plastic scintillation counters 180 cm long located at 120 cm from the target. Neutron energy spectra are measured by time-of-flight in the 300 keV-15 MeV range with good energy resolution. The device was tested with several known nuclei. Its performances are discussed in comparison with Monte Carlo simulations. They very high overall detection efficiency on the TONNERRE array made it possible to study one and two neutron emission of {sup 11}Li. A complete decay scheme was obtained. The {sup 33}Mg and {sup 35}Al beta decays were investigated for the first time by neutron and gamma spectroscopy. Complete decay schemes were established and compared to large scale shell-model calculations. (authors)

  1. Study of neutron-rich nuclei structure around the N=28 shell closure using the in-beam gamma spectroscopy technique; Etude de la structure des noyaux riches en neutrons autour de la fermeture de couches N=28 par spectroscopie gamma en ligne

    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)

  2. Study of the neutron-rich nuclei with N=21, sup 3 sup 5 Si and sup 3 sup 3 Mg, by beta decay of sup 3 sup 5 Al and sup 3 sup 3 Na

    CERN Document Server

    Nummela, S; Caurier, E; Courtin, S; Dessagne, P; Holmlund, E; Jokinen, A; Knipper, A; Le Scornet, G; Mieh, C; Nowacki, F; Lyapin, L G; Oinonen, M; Poirier, E; Radivojevic, Z; Ramdhane, M; Trzaska, W H; Walter, G; Äystö, J

    2002-01-01

    The first information on the level structure of the N=21 nuclei, sup 3 sup 5 Si and sup 3 sup 3 Mg, has been obtained by the beta decay study of sup 3 sup 5 Al and sup 3 sup 3 Na, produced by fragmentation of an UC target with 1.4 GeV protons at CERN/ISOLDE. The experimental technique involved beta-gamma, beta-gamma-gamma, and beta-n-gamma coincidences, neutron spectra being obtained by time of flight measurements. Gamma detection was made either using large Ge counters or small BaF sub 2 scintillators (for lifetime measurements). In the case of the sup 3 sup 5 Al decay, (T sub 1 sub / sub 2 =41.6(2.2) ms), a simple structure has been found for the level scheme of sup 3 sup 5 Si (Z=14, N=21) which has been interpreted with the level sequence : 7/2 sup - , 3/2 sup - and 3/2 sup + corresponding respectively to the ground state and the states at 910 and 974 keV. The life-time of the 974 keV [T sub 1 sub / sub 2 =5.9(6) ns] is found consistent with the proposed level scheme and multipolarities. The investigation ...

  3. Isomer spectroscopy of neutron-rich 168 Tb 103

    Energy Technology Data Exchange (ETDEWEB)

    Gurgi, L. A.; Regan, P. H.; Söderström, P. -A.; Watanabe, H.; Walker, P. M.; Podolyák, Zs.; Nishimura, S.; Berry, T. A.; Doornenbal, P.; Lorusso, G.; Isobe, T.; Baba, H.; Xu, Z. Y.; Sakurai, H.; Sumikama, T.; Catford, W. N.; Bruce, A. M.; Browne, F.; Lane, G. J.; Kondev, F. G.; Odahara, A.; Wu, J.; Liu, H. L.; Xu, F. R.; Korkulu, Z.; Lee, P.; Liu, J. J.; Phong, V. H.; Yag, A.; Zhang, G. X.; Alharbi, T.; Carroll, R. J.; Chae, K. Y.; Dombradi, Zs.; Estrade, A.; Fukuda, N.; Griffin, C.; Ideguchi, E.; Inabe, N.; Kanaoka, H.; Kojouharov, I.; Kubo, T.; Kubono, S.; Kurz, N.; Kuti, I.; Lalkovski, S.; Lee, E. J.; Lee, C. S.; Lotay, G.; Moon, C. -B.; Nishizuka, I.; Nita, C. R.; Patel, Z.; Roberts, O. J.; Schaffner, H.; Shand, C. M.; Suzuki, H.; Takeda, H.; Terashima, S.; Vajta, Zs.; Yoshida, S.; Valiente-Dòbon, J. J.

    2017-11-01

    In-flight fission of a 345 MeV per nucleon 238U primary beam on a 2 mm thick 9Be target has been used to produce and study the decays of a range of neutron-rich nuclei centred around the doubly mid-shell nucleus 170Dy at the RIBF Facility, RIKEN, Japan. The produced secondary fragments of interest were identified event-by-event using the BigRIPS separator. The fragments were implanted into the WAS3ABI position sensitive silicon active stopper which allowed pixelated correlations between implants and their subsequent β-decay. Discrete γ-ray transitions emitted following decays from either metastable states or excited states populated following beta decay were identified using the 84 coaxial high-purity germanium (HPGe) detectors of the EURICA spectrometer, which was complemented by 18 additional cerium-doped lanthanum bromide (LaBr3) fast-timing scintillation detectors from the FATIMA collaboration. This paper presents the internal decay of a metastable isomeric excited state in the odd-odd nucleus 168Tb, which corresponds to a single proton-neutron hole configuration in the valence maximum nucleus 170Dy. These data represent the first information on excited states in this nucleus, which is the most neutron-rich odd-odd isotope of terbium (Z=65) studied to date. Nilsson configurations associated with an axially symmetric, prolate-deformed nucleus are proposed for the 168Tb ground state the observed isomeric state by comparison with Blocked BCS-Nilsson calculations.

  4. Isomer spectroscopy of neutron-rich 168Tb103

    Science.gov (United States)

    Gurgi, L. A.; Regan, P. H.; Söderström, P.-A.; Watanabe, H.; Walker, P. M.; Podolyák, Zs.; Nishimura, S.; Berry, T. A.; Doornenbal, P.; Lorusso, G.; Isobe, T.; Baba, H.; Xu, Z. Y.; Sakurai, H.; Sumikama, T.; Catford, W. N.; Bruce, A. M.; Browne, F.; Lane, G. J.; Kondev, F. G.; Odahara, A.; Wu, J.; Liu, H. L.; Xu, F. R.; Korkulu, Z.; Lee, P.; Liu, J. J.; Phong, V. H.; Yag, A.; Zhang, G. X.; Alharbi, T.; Carroll, R. J.; Chae, K. Y.; Dombradi, Zs.; Estrade, A.; Fukuda, N.; Griffin, C.; Ideguchi, E.; Inabe, N.; Kanaoka, H.; Kojouharov, I.; Kubo, T.; Kubono, S.; Kurz, N.; Kuti, I.; Lalkovski, S.; Lee, E. J.; Lee, C. S.; Lotay, G.; Moon, C.-B.; Nishizuka, I.; Nita, C. R.; Patel, Z.; Roberts, O. J.; Schaffner, H.; Shand, C. M.; Suzuki, H.; Takeda, H.; Terashima, S.; Vajta, Zs.; Yoshida, S.; Valiente-Dòbon, J. J.

    2017-11-01

    In-flight fission of a 345 MeV per nucleon 238U primary beam on a 2 mm thick 9Be target has been used to produce and study the decays of a range of neutron-rich nuclei centred around the doubly mid-shell nucleus 170Dy at the RIBF Facility, RIKEN, Japan. The produced secondary fragments of interest were identified event-by-event using the BigRIPS separator. The fragments were implanted into the WAS3ABI position sensitive silicon active stopper which allowed pixelated correlations between implants and their subsequent β-decay. Discrete γ-ray transitions emitted following decays from either metastable states or excited states populated following beta decay were identified using the 84 coaxial high-purity germanium (HPGe) detectors of the EURICA spectrometer, which was complemented by 18 additional cerium-doped lanthanum bromide (LaBr3) fast-timing scintillation detectors from the FATIMA collaboration. This paper presents the internal decay of a metastable isomeric excited state in the odd-odd nucleus 168Tb, which corresponds to a single proton-neutron hole configuration in the valence maximum nucleus 170Dy. These data represent the first information on excited states in this nucleus, which is the most neutron-rich odd-odd isotope of terbium (Z=65) studied to date. Nilsson configurations associated with an axially symmetric, prolate-deformed nucleus are proposed for the 168Tb ground state the observed isomeric state by comparison with Blocked BCS-Nilsson calculations.

  5. Structure of Light neutron-rich nuclei probing 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 : magic numbers Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 0.810, year: 2006

  6. Single-Particle Structure of Neutron-Rich Nuclei

    International Nuclear Information System (INIS)

    Cizewski, Jolie; Jones, K.L.; Thomas, J.S.; Bardayan, Daniel W.; Blackmon, Jeff C.; Gross, Carl J.; Liang, J. Felix; Shapira, Dan; Smith, Michael Scott; Stracener, Daniel W.; Kozub, R.L.; Nesaraja, Caroline D.; Greife, U.; Livesay, Jake; Ma, Zhanwen

    2004-01-01

    Neutron transfer (d,p) reactions have been measured with rare isotope beams of 132Sn, 130Sn and 134Te accelerated to ∼4.5 MeV/u interacting with CD2 targets. Reaction protons were detected in an early implementation of the ORRUBA array of position-sensitive silicon strip detectors. Neutron excitations in the 2f7/2, 3p3/2, 3p1/2 and 2f5/2 orbitals were populated.

  7. Two-neutron removal reactions for very neutron rich nuclei

    International Nuclear Information System (INIS)

    Riisager, K.; Hansen, P.G.; Anne, R.; Lewitowicz, M.; Arnell, S.E.; Neugart, R.; Richter, A.; Bimbot, R.; Guillemaud-Mueller, D.

    1992-01-01

    The two-neutron removal reactions of beams of 11 Li, 14 Be and 8 He upon Be, Ni and Au targets were studied at 30 MeV/u. The cross-sections and the neutron forward angular distributions were measured; they correlate strongly with the two-neutron separation energy of the projectile. Even though the coverage of the neutron detectors was limited, a rough neutron-neutron distribution could be extracted. A simplified interpretation of the data is presented. (author) 57 refs., 7 figs., 2 tabs

  8. Theoretical study on production of heavy neutron-rich isotopes around the N=126 shell closure in radioactive beam induced transfer reactions

    Directory of Open Access Journals (Sweden)

    Long Zhu

    2017-04-01

    Full Text Available In order to produce more unknown neutron-rich nuclei around N=126, the transfer reactions 136Xe + 198Pt, 136–144Xe + 208Pb, and 132Sn + 208Pb are investigated within the framework of the dinuclear system (DNS model. The influence of neutron excess of projectile on production cross sections of target-like products is studied through the reactions 136,144Xe + 208Pb. We find that the radioactive projectile 144Xe with much larger neutron excess is favorable to produce neutron-rich nuclei with charge number less than the target rather than produce transtarget nuclei. The incident energy dependence of yield distributions of fragments in the reaction 132Sn + 208Pb are also studied. The production cross sections of neutron-rich nuclei with Z=72–77 are predicted in the reactions 136–144Xe + 208Pb and 132Sn + 208Pb. It is noticed that the production cross sections of unknown neutron-rich nuclei in the reaction 144Xe + 208Pb are at least two orders of magnitude larger than those in the reaction 136Xe + 208Pb. The radioactive beam induced transfer reactions 139,144Xe + 208Pb, considering beam intensities proposed in SPIRAL2 (Production System of Radioactive Ion and Acceleration On-Line project as well, for production of neutron-rich nuclei around the N=126 shell closure are investigated for the first time. It is found that, in comparison to the stable beam 136Xe, the radioactive beam 144Xe shows great advantages for producing neutron-rich nuclei with N=126 and the advantages get more obvious for producing nuclei with less charge number.

  9. Theoretical study on production of heavy neutron-rich isotopes around the N = 126 shell closure in radioactive beam induced transfer reactions

    Science.gov (United States)

    Zhu, Long; Su, Jun; Xie, Wen-Jie; Zhang, Feng-Shou

    2017-04-01

    In order to produce more unknown neutron-rich nuclei around N = 126, the transfer reactions 136Xe + 198Pt, 136-144Xe + 208Pb, and 132Sn + 208Pb are investigated within the framework of the dinuclear system (DNS) model. The influence of neutron excess of projectile on production cross sections of target-like products is studied through the reactions 136,144Xe + 208Pb. We find that the radioactive projectile 144Xe with much larger neutron excess is favorable to produce neutron-rich nuclei with charge number less than the target rather than produce transtarget nuclei. The incident energy dependence of yield distributions of fragments in the reaction 132Sn + 208Pb are also studied. The production cross sections of neutron-rich nuclei with Z = 72- 77 are predicted in the reactions 136-144Xe + 208Pb and 132Sn + 208Pb. It is noticed that the production cross sections of unknown neutron-rich nuclei in the reaction 144Xe + 208Pb are at least two orders of magnitude larger than those in the reaction 136Xe + 208Pb. The radioactive beam induced transfer reactions 139,144Xe + 208Pb, considering beam intensities proposed in SPIRAL2 (Production System of Radioactive Ion and Acceleration On-Line) project as well, for production of neutron-rich nuclei around the N = 126 shell closure are investigated for the first time. It is found that, in comparison to the stable beam 136Xe, the radioactive beam 144Xe shows great advantages for producing neutron-rich nuclei with N = 126 and the advantages get more obvious for producing nuclei with less charge number.

  10. Delayed Particle Study of Neutron Rich Lithium Isotopes

    CERN Multimedia

    Marechal, F; Perrot, F

    2002-01-01

    We propose to make a systematic complete coincidence study of $\\beta$-delayed particles from the decay of neutron-rich lithium isotopes. The lithium isotopes with A=9,10,11 have proven to contain a vast information on nuclear structure and especially on the formation of halo nuclei. A mapping of the $\\beta$-strength at high energies in the daughter nucleus will make possible a detailed test of our understanding of their structure. An essential step is the comparison of $\\beta$-strength patterns in $^{11}$Li and the core nucleus $^{9}$Li, another is the full characterization of the break-up processes following the $\\beta$-decay. To enable such a measurement of the full decay process we will use a highly segmented detection system where energy and emission angles of both charged and neutral particles are detected in coincidence and with high efficiency and accuracy. We ask for a total of 30 shifts (21 shifts for $^{11}$Li, 9 shifts $^{9}$Li adding 5 shifts for setting up with stable beam) using a Ta-foil target...

  11. Radiochemical search for neutron-rich isotopes of element 107

    International Nuclear Information System (INIS)

    Schaedel, M.

    1987-01-01

    Recent mass calculations have indicated that there is a region of deformed nuclei around neutron number N=162 that is especially stable against spontaneous fission. Barrier heights of about 5 MeV for Z = 107 nuclides can be extrapolated. To search for new, neutron-rich isotopes of element 107 in radiochemical experiments with 254 Es as a target an on-line chemical separation of element 107 (EKA-Rhenium), especially from the actinide elements is needed. An on-line gas-phase chemistry was developed with the homolog Re based on the volatility of the oxide which is transported in an O 2 containing atmosphere along a temperature gradient in a quartz tube and is condensed onto a thin Ta coated Ni-foil. The authors applied this technique in two series of experiments with their rotating wheel on-line gas-phase chemistry apparatus at the 88-inch cyclotron where they irradiated 254 Es as a target with 93 MeV and 96 MeV 16 O ions to search for 266 107. The assignment of the observed alpha events between 8 and 9 MeV to possibly (1) non actinide contaminants like 212 Po, (2) known isotopes of heavy elements like 261 105, or (3) a new isotope will be discussed

  12. New K isomers in the neutron-rich N =100 isotones 162Sm, 163Eu, and 164Gd

    Science.gov (United States)

    Yokoyama, R.; Go, S.; Kameda, D.; Kubo, T.; Inabe, N.; Fukuda, N.; Takeda, H.; Suzuki, H.; Yoshida, K.; Kusaka, K.; Tanaka, K.; Yanagisawa, Y.; Ohtake, M.; Sato, H.; Shimizu, Y.; Baba, H.; Kurokawa, M.; Nishimura, D.; Ohnishi, T.; Iwasa, N.; Chiba, A.; Yamada, T.; Ideguchi, E.; Fujii, T.; Nishibata, H.; Ieki, K.; Murai, D.; Momota, S.; Sato, Y.; Hwang, J. W.; Kim, S.; Tarasov, O. B.; Morrissey, D. J.; Sherrill, B. M.; Simpson, G.; Praharaj, C. R.

    2017-03-01

    Very neutron-rich Z ˜60 isotopes produced by in-flight fission of a 345 MeV/nucleon 238U beam at the RI Beam Factory, RIKEN Nishina Center, have been studied by delayed γ -ray spectroscopy. New isomers were discovered in the neutron-rich N =100 isotones 162Sm, 163Eu, and 164Gd. Half-lives, γ -ray energies, and relative intensities of these isomers were obtained. Level schemes were proposed for these nuclei and the first 2+ and 4+ states were assigned for the even-even nuclei. The first 2+ and 4+ state energies decrease as the proton numbers get smaller. The energies and the half-lives of the new isomers are very similar to those of 4- isomers known in less neutron-rich N =100 isotones 168Er and 170Yb. A deformed Hartree-Fock with angular momentum projection model suggests Kπ=4- two-quasiparticle states with ν 7 /2 [633 ]⊗ν 1 /2 [521 ] configurations with similar excitation energy. The results suggest that neutron-rich N =100 nuclei are well deformed and the deformation gets larger as Z decreases to 62. The onset of K isomers with the same configuration at almost the same energy in N =100 isotones indicates that the neutron single-particle structures of neutron-rich isotones down to Z =62 do not change significantly from those of the Z =70 stable nuclei. Systematics of the excitation energies of new isomers can be explained without the predicted N =100 shell gap.

  13. A double potential model for neutron halo nuclei

    OpenAIRE

    Abbas, Afsar

    2003-01-01

    It is shown here that loosely bound halo structure of neutron rich nuclei and the ground state spin of single neutron halo nuclei are correlated and are consistently explained if one assumes a double potential shell model for these nuclei.

  14. β decay and isomeric properties of neutron-rich Ca and Sc isotopes

    International Nuclear Information System (INIS)

    Crawford, H. L.; Mantica, P. F.; Berryman, J. S.; Stoker, J. B.; Janssens, R. V. F.; Carpenter, M. P.; Kay, B. P.; Lauritsen, T.; Zhu, S.; Broda, R.; Cieplicka, N.; Fornal, B.; Grinyer, G. F.; Minamisono, K.; Hoteling, N.; Stefanescu, I.; Walters, W. B.

    2010-01-01

    The isomeric and β-decay properties of neutron-rich 53-57 Sc and 53,54 Ca nuclei near neutron number N=32 are reported, and the low-energy level schemes of 53,54,56 Sc and 53-57 Ti are presented. The low-energy level structures of the 21 Sc isotopes are discussed in terms of the coupling of the valence 1f 7/2 proton to states in the corresponding 20 Ca cores. Implications with respect to the robustness of the N=32 subshell closure are discussed, as well as the repercussions for a possible N=34 subshell closure.

  15. Study of neutron-rich $^{51−53}$ Ca isotopes via $\\beta$-decay

    CERN Multimedia

    The high Q$_\\beta$ values in certain neutron-rich regions of the chart of nuclides opens up the possibility to study states in the daughter nuclei which lie at high excitation energy, above the neutron separation threshold. We propose to perform spectroscopy of the $\\beta$-delayed neutron emission of the $^{51-53}$K isotopes to study the population of single-particle or particle-hole states both below and above the neutron separation threshold. The VANDLE neutron detector will be used in combination with the IDS tape station setup and Ge detectors.

  16. The CARDS array for neutron-rich decay spectroscopy at HRIBF

    CERN Document Server

    Batchelder, J C; Bingham, C R; Carter, H K; Cole, J D; Fong, D; Garrett, P E; Grzywacz, R; Hamilton, J H; Hartley, D J; Hwang, J K; Krolas, W; Kulp, D C; Larochelle, Y; Piechaczek, A; Ramayya, A V; Rykaczewski, K; Spejewski, E H; Stracener, D W; Tantawy, M N; Winger, J A; Wood, J; Zganjar, E F

    2003-01-01

    An array for decay studies of neutron-rich nuclei has been commissioned for use at the UNISOR separator at Holifield Radioactive Ion Beam Facility. This array consists of three segmented clover Ge detectors, plastic scintillators, and a high-resolution (approx 1 keV) Si conversion electron spectrometer. These detectors are mounted on a support that surrounds a moving tape collector. This system has been named clover array for radioactive decay studies. The detectors have been outfitted with digital flash ADCs (XIA DGFs) that fit the preamp signals, with built-in pileup rejection.

  17. The CARDS array for neutron-rich decay spectroscopy at HRIBF

    International Nuclear Information System (INIS)

    Batchelder, J.C.; Bilheux, J.-C.; Bingham, C.R.; Carter, H.K.; Cole, J.D.; Fong, D.; Garrett, P.E.; Grzywacz, R.; Hamilton, J.H.; Hartley, D.J.; Hwang, J.K.; Krolas, W.; Kulp, D.; Larochelle, Y.; Piechaczek, A.; Ramayya, A.V.; Rykaczewski, K.P.; Spejewski, E.H.; Stracener, D.W.; Tantawy, M.N.; Winger, J.A.; Wood, J.; Zganjar, E.F.

    2003-01-01

    An array for decay studies of neutron-rich nuclei has been commissioned for use at the UNISOR separator at Holifield Radioactive Ion Beam Facility. This array consists of three segmented clover Ge detectors, plastic scintillators, and a high-resolution (∼1 keV) Si conversion electron spectrometer. These detectors are mounted on a support that surrounds a moving tape collector. This system has been named clover array for radioactive decay studies. The detectors have been outfitted with digital flash ADCs (XIA DGFs) that fit the preamp signals, with built-in pileup rejection

  18. The spectroscopy of neutron-rich 35P and 37P

    International Nuclear Information System (INIS)

    In the last decade there has been an increasing interest in using deep-inelastic processes to populate and study neutron-rich nuclei. With thick target measurements, use of this reaction has led to the requirement of a high efficiency Ge gamma detector array in order to carry out high fold coincidence measurements to resolve the γ-ray cascades of the many final nuclei produced, particularly since many of them are produced with low cross-sections. An alternative approach to studying such nuclei via this reaction has been to use a magnetic spectrometer in conjunction with a high efficiency Ge detector array enabling the projectile/target-like fragments to be detected in coincidence with their associated γ-ray, thus overcoming some of the problems in identifying the origin of the emitted γ-ray, particularly in cases where there have been no previously observed γ-ray transitions. In this report are presented the results obtained using such a method in the study of neutron-rich P isotopes

  19. Precision mass measurements on neutron-rich Zn isotopes and their consequences on the astrophysical r-process

    Energy Technology Data Exchange (ETDEWEB)

    Baruah, Sudarshan

    2008-07-15

    The rapid neutron-capture or the r-process is responsible for the origin of about half of the neutron-rich atomic nuclei in the universe heavier than iron. For the calculation of the abundances of those nuclei, atomic masses are required as one of the input parameters with very high precision. In the present work, the masses of the neutron rich Zn isotopes (A=71 to 81) lying in the r-process path have been measured in the ISOLTRAP experiment at ISOLDE/CERN. The mass of {sup 81}Zn has been measured directly for the rst time. The half-lives of the nuclides ranged from 46.5 h ({sup 72}Zn) down to 290 ms ({sup 81}Zn). In case of all the nuclides, the relative mass uncertainty ({delta}m=m) achieved was in the order of 10{sup -8} corresponding to a 100-fold improvement in precision over previous measurements. (orig.)

  20. Production of neutron-rich nuclides in the vicinity of N = 126 shell closure in multinucleon transfer reactions

    Directory of Open Access Journals (Sweden)

    Karpov Alexander

    2017-01-01

    Full Text Available Multinucleon transfer in low-energy nucleus-nucleus collisions is widely discussed as a method of production of yet-unknown neutron-rich nuclei hardly accessible (or inaccessible by other methods. Modeling of complicated dynamics of nuclear reactions induced by heavy ions is done within a multidimensional dynamical model of nucleus-nucleus collisions based on the Langevin equations. The model gives a continuous description of the system evolution starting from the well-separated target and projectile in the entrance channel of the reaction up to the formation of final reaction products. In this paper, rather recent sets of experimental data for the 136Xe+198Pt,208Pb reactions are analyzed together with the production cross sections for neutron-rich nuclei in the vicinity of the N = 126 magic shell.

  1. Study of Neutron-Rich $^{124,126,128}$Cd Isotopes; Excursion from Symmetries to Shell-Model Picture

    CERN Multimedia

    Nieminen, A M; Reponen, M

    2002-01-01

    A short outline is given on a number of topics that are present in the long series of even-even Cd nuclei and therefore, may turn out to constitute an ideal test bench in order to verify a number of theoretical ideas on how collective motion, near closed shells, builds up taking into account both the valence and core nucleons when studying the nucleon correlations. Moreover, these experiments can reveal new challenges when moving towards very neutron-rich systems.

  2. Properties of neutron-rich hafnium high-spin isomers

    CERN Multimedia

    Tungate, G; Walker, P M; Neyens, G; Billowes, J; Flanagan, K; Koester, U H; Litvinov, Y

    It is proposed to study highly-excited multi-quasiparticle isomers in neutron-rich hafnium (Z=72) isotopes. Long half-lives have already been measured for such isomers in the storage ring at GSI, ensuring their accessibility with ISOL production. The present proposal focuses on:\\\\ (i) an on-line experiment to measure isomer properties in $^{183}$Hf and $^{184}$Hf, and\\\\ (ii) an off-line molecular breakup test using REXTRAP, to provide Hf$^{+}$ beams for future laser spectroscopy and greater sensitivity for the future study of more neutron-rich isotopes.

  3. Physics of Unstable Nuclei

    Science.gov (United States)

    Khoa, Dao Tien; Egelhof, Peter; Gales, Sydney; Giai, Nguyen Van; Motobayashi, Tohru

    2008-04-01

    . -- Thermal pairing in nuclei / N. D. Dang -- Molecular-orbital and di-nuclei states in Ne and F isotopes / M. Kimura -- Low-momentum interactions for nuclei / A. Schwenk -- Nonrelativistic nuclear energy functionals including the tensor force / G. Colo et al. -- New aspects on dynamics in nuclei described by covariant density functional theory / P. Ring, D. Pena -- Theoretical studies on ground-state properties of superheavy nuclei / Z. Z. Ren et al. -- New results in the study of superfluid nuclei: many-body effects, spectroscopic factors / P. F. Bortignon et al. -- New Effective nucleon-nucleon interaction for the mean-field approximation / V. K. Au et al. -- Linear response calculations with the time-dependent Skyrme density functional / T. Nakatsukasa et al. -- Dissipative dynamics with exotic beams / M. Di Toro et al. -- Exploring the symmetry energy of asymmetric nuclear matter with heavy ion reactions / M. B. Tsang -- Invariant mass spectroscopy of halo nuclei / T. Nakamura et al. -- Core [symbol] structures in [symbol]C, [symbol]C and [symbol]C up to high excitation energies / H. G. Bohlen et al. -- Light neutron-rich nuclei studied by alpha-induced reactions / S. Shimoura -- Fusion and direct reactions around the Coulomb barrier for the system [symbol]He + [symbol]Zn / V. Scuderi et al. -- Analyzing power measurement for proton elastic scattering on [symbol]He / S. Sakaguchi et al. -- Knockout reaction spectroscopy of exotic nuclei / J. A. Tostevin -- Exotic nuclei, quantum phase transitions, and the evolution of structure / R. F. Casten -- Structure of exotic nuclei in the medium mass region / T. Otsuka -- Pairing correlations in halo nuclei / H. Sagawa, K. Hagino -- Experimental approach to high-temperature Stellar reactions with low-energy RI beams / S. Kubono et al. -- Transition to quark matter in neutron stars / G. X. Peng et al. -- Research at VATLY: main themes and recent results / P. N. Diep et al. -- Study of the astrophysical reaction [symbol

  4. High-spin structure of neutron-rich Dy isotopes

    Indian Academy of Sciences (India)

    Abstract. In view of recent experimental progress on production and spectroscopy of neutron-rich isotopes of Dy with mass number A. 166 and 168, we have made theoretical investigations on the structure of high spin states of164 170Dy isotopes in the cranked Hartree–Fock–Bogoliubov (CHFB) theory employing a ...

  5. Recent results on neutron rich tin isotopes by laser spectroscopy

    CERN Document Server

    Roussière, B; Crawford, J E; Essabaa, S; Fedosseev, V; Geithner, W; Genevey, J; Girod, M; Huber, G; Horn, R; Kappertz, S; Lassen, J; Le Blanc, F; Lee, J K P; Le Scornet, G; Lettry, Jacques; Mishin, V I; Neugart, R; Obert, J; Oms, J; Ouchrif, A; Peru, S; Pinard, J; Ravn, H L; Sauvage, J; Verney, D

    2001-01-01

    Laser spectroscopy measurements have been performed on neutron rich tin isotopes using the COMPLIS experimental setup. The nuclear charge radii of the even-even isotopes from A=108 to 132 are compared to the results of macroscopic and microscopic calculations. The improvements and optimizations needed to perform the isotope shift measurement on $^{134}$Sn are presented.

  6. $\\beta$-decay study of neutron-rich Tl, Pb, and Bi by means of the pulsed-release technique and resonant laser ionisation

    CERN Multimedia

    Lettry, J

    2002-01-01

    It is proposed to study new neutron-rich nuclei around the Z = 82 magic shell closure, with major relevance for understanding the evolution of nuclear structure at extreme isospin values. Following the IS354 experiment, $\\beta$-decay studies of neutron-rich thallium, lead and bismuth isotopes will be performed for 215 $\\leqslant$ A $\\leqslant$ 219. To this purpose the pulsed-release technique, which was pioneered at ISOLDE, will be optimised. It will be complemented with the higher element selectivity that can be obtained by the unique features of resonant laser ionisation, available at ISOLDE from the RILIS source.

  7. Investigation of very neutron-rich Fe, Co and Ni isotopes encountered along the r-process path

    International Nuclear Information System (INIS)

    Czajkowski, S.; Bernas, M.; Sida, J.L.; Dessagne, P.; Miehe, C.; Pujol, C.

    1992-01-01

    Very neutron-rich nuclei beyond Fe must be investigated in order to understand the r-process. New Ni, Co and Fe isotopes, with ten to twelve neutrons more than the heaviest stable isotopes, were discovered in the thermal fission of 235 U and 239 Pu, and their half-lives were deduced from the analysis of time delayed coincidences between the fragment implantation and the detection of consecutive β-particles in the same Si-pin diode detector. In a pilot experiment, high energy projectile fragmentation was exploited to produce neutron rich species. The fragments of interest were separated and energy bunched with the FRS. After being slowed down, they were selectively implanted in a similar detecting system. The β decay half-life were obtained as in the previous case

  8. Mechanisms for radiative capture in medium-mass nuclei

    International Nuclear Information System (INIS)

    Lynn, J.E.

    1979-01-01

    This paper is a review of the current state of theory on neutron capture, particularly at low neutron energies, and of its relevance for calculations of radiative capture cross-sections for fission reactor applications. In this context, the review is mostly confined to electric dipole transitions, these being believed to be by far the most important contribution overall to the total capture cross-section, although the evidence from high-energy transitions are certainly not negligible

  9. Development of axial asymmetry in the neutron-rich nucleus {sup 110}Mo

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, H., E-mail: hiroshi@ribf.riken.jp [RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Yamaguchi, K.; Odahara, A. [Department of Physics, Osaka University, Machikaneyama-machi 1-1, Osaka 560-0043 Toyonaka (Japan); Sumikama, T. [Department of Physics, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba (Japan); Nishimura, S. [RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Yoshinaga, K. [Department of Physics, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba (Japan); Li, Z. [RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Miyashita, Y. [Department of Physics, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba (Japan); Sato, K. [RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Prochniak, L. [Institute of Physics, Maria Curie-Sklodowska University, pl. M. Curie-Sklodowskiej 1, 20-031 Lublin (Poland); Baba, H. [RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Berryman, J.S. [Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Blasi, N. [INFN, Sezione di Milano, via Celoria 16, I-20133 Milano (Italy); Bracco, A.; Camera, F. [INFN, Sezione di Milano, via Celoria 16, I-20133 Milano (Italy); Dipartimento di Fisica, Universita di Milano, via Celoria 16, I-20133 Milano (Italy); Chiba, J. [Department of Physics, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba (Japan); Doornenbal, P. [RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Go, S.; Hashimoto, T.; Hayakawa, S. [Center for Nuclear Study, University of Tokyo, Hirosawa 2-1, Wako, Saitama 351-0198 (Japan)

    2011-10-19

    The neutron-rich nucleus {sup 110}Mo has been investigated by means of {gamma}-ray spectroscopy following the {beta}-decay of {sup 110}Nb, produced using in-flight fission of a {sup 238}U beam at 345 MeV/nucleon at the RIBF facility. In addition to the ground-band members reported previously, spectroscopic information on the low-lying levels of the quasi-{gamma} band built on the second 2{sup +} state at 494 keV has been obtained for the first time. The experimental finding of the second 2{sup +} state being lower than the yrast 4{sup +} level suggests that axially-asymmetric {gamma} softness is substantially enhanced in this nucleus. The experimental results are compared with model calculations based on the general Bohr Hamiltonian method. The systematics of the low-lying levels in even-even A{approx}110 nuclei is discussed in comparison with that in the neutron-rich A{approx}190 region, by introducing the quantity E{sub S}/E(2{sub 1}{sup +}), E{sub S}=E(2{sub 2}{sup +})-E(4{sub 1}{sup +}), as a global signature of the structural evolution involving axial asymmetry.

  10. New neutron-rich isotope production in 154Sm+160Gd

    Directory of Open Access Journals (Sweden)

    Ning Wang

    2016-09-01

    Full Text Available Deep inelastic scattering in 154Sm+160Gd at energies above the Bass barrier is for the first time investigated with two different microscopic dynamics approaches: improved quantum molecular dynamics (ImQMD model and time dependent Hartree–Fock (TDHF theory. No fusion is observed from both models. The capture pocket disappears for this reaction due to strong Coulomb repulsion and the contact time of the di-nuclear system formed in head-on collisions is about 700 fm/c at an incident energy of 440 MeV. The isotope distribution of fragments in the deep inelastic scattering process is predicted with the simulations of the latest ImQMD-v2.2 model together with a statistical code (GEMINI for describing the secondary decay of fragments. More than 40 extremely neutron-rich unmeasured nuclei with 58≤Z≤76 are observed and the production cross sections are at the order of μb to mb. The multi-nucleon transfer reaction of Sm+Gd could be an alternative way to synthesize new neutron-rich lanthanides which are difficult to be produced with traditional fusion reactions or fission of actinides.

  11. Odd-even parity splittings and octupole correlations in neutron-rich Ba isotopes

    Science.gov (United States)

    Fu, Y.; Wang, H.; Wang, L.-J.; Yao, J. M.

    2018-02-01

    The odd-even parity splittings in low-lying parity-doublet states of atomic nuclei with octupole correlations have usually been interpreted as rotational excitations on top of octupole vibration in the language of collective models. In this paper, we report a deep analysis of the odd-even parity splittings in the parity-doublet states of neutron-rich Ba isotopes around neutron number N =88 within a full microscopic framework of beyond-mean-field multireference covariant energy density functional theory. The dynamical correlations related to symmetry restoration and quadrupole-octupole shape fluctuation are taken into account with a generator coordinate method combined with parity, particle-number, and angular-momentum projections. We show that the behavior of odd-even parity splittings is governed by the interplay of rotation, quantum tunneling, and shape evolution. Similar to 224Ra, a picture of rotation-induced octupole shape stabilization in the positive-parity states is exhibited in the neutron-rich Ba isotopes.

  12. Decay properties of some neutron-rich praseodymium isotopes

    International Nuclear Information System (INIS)

    Skarnemark, G.; Aronsson, P.O.; Stender, E.; Trautmann, N.; Kaffrell, N.; Bjoernstad, T.; Kvale, E.; Skarestad, M.

    1976-01-01

    Neutron-rich Pr isotopes produced in the thermal neutron-induced fission of 235 U have been investigated by means of γ-γ coincidence experiments. The nuclides have been separated from the fission product mixture, using the fast chemical separation system SISAK in connection with a gas jet recoil transport system. The results include assignments of several new γ-ray energies and partial decay schemes for 147 Pr, 148 Pr, 149 Pr and 150 Pr. (orig.) [de

  13. β decay of neutron-rich 53-56Ca

    International Nuclear Information System (INIS)

    Mantica, P. F.; Crawford, H. L.; Damaske, A.; Pinter, J. S.; Stoker, J. B.; Broda, R.; Fornal, B.; Hecht, A. A.; Hoteling, N.; Hoffman, C.; Tabor, S. L.; Walters, W. B.; Horoi, M.; Janssens, R. V. F.; Zhu, S.; Pereira, J.; Sumikama, T.; Wang, X.

    2008-01-01

    β-decay properties of neutron-rich Ca isotopes have been obtained. Half-life values were determined for the first time for 54 Ca (86±7 ms), 55 Ca (22±2 ms), and 56 Ca (11±2 ms). The half-life of 230±60 ms deduced for 53 Ca is significantly longer than reported previously, where the decay chain 53 K → 53 Ca → 53 Sc was considered. A delayed γ ray with an energy of 247 keV was identified following β decay of 54 Ca and is proposed to depopulate the 1 1 + level in 54 Sc. The β-decay properties compare favorably with the results of shell-model calculations completed in the full pf space with the GXPF1 interaction. The half-lives of the neutron-rich Ca isotopes are also compared with gross β-decay theory. The systematic trend of the neutron-rich Ca half-lives is consistent with the presence of a subshell gap at N=32

  14. $\\beta$-decay study of neutron-rich Tl and Pb isotopes

    CERN Multimedia

    It is proposed to study the structure of neutron-rich nuclei beyond $^{208}$Pb. The one-proton hole $^{211-215}$Tl and the semi magic $^{213}$Pb will be produced and studied via nuclear and atomic spectroscopy searching for long-lived isomers and investigating the $\\beta$-delayed $\\gamma$- emission to build level schemes. Information on the single particle structure in $^{211-215}$Pb, especially the position of the g$_{9/2}$ and i$_{11/2}$ neutron orbitals, will be extracted along with lifetimes. The $\\beta$-decay will be complemented with the higher spin selectivity that can be obtained by resonant laser ionization to single-out the decay properties of long-living isomers in $^{211,213}$Tl and $^{213}$Pb.

  15. Evidence for a smooth onset of deformation in the neutron-rich Kr isotopes

    CERN Document Server

    Albers, M; Nomura, K; Blazhev, A; Jolie, J; Mucher, D; Bastin, B; Bauer, C; Bernards, C; Bettermann, L; Bildstein, V; Butterworth, J; Cappellazzo, M; Cederkall, J; Cline, D; Darby, I; Das Gupta, S; Daugas, J M; Davinson, T; De Witte, H; Diriken, J; Filipescu, D; Fiori, E; Fransen, C; Gaffney, L P; Georgiev, G; Gernhauser, R; Hackstein, M; Heinze, S; Hess, H; Huyse, M; Jenkins, D; Konki, J; Kowalczyk, M; Kroll, T; Krucken, R; Litzinger, J; Lutter, R; Marginean, N; Mihai, C; Moschner, K; Napiorkowski, P; Nara Singh, B S; Nowak, K; Otsuka, T; Pakarinen, J; Pfeiffer, M; Radeck, D; Reiter, P; Rigby, S; Robledo, L M; Rodriguez-Guzman, R; Rudigier, M; Sarriguren, P; Scheck, M; Seidlitz, M; Siebeck, B; Simpson, G; Thole, P; Thomas, T; Van de Walle, J; Van Duppen, P; Vermeulen, M; Voulot, D; Wadsworth, R; Wenander, F; Wimmer, K; Zell, K O; Zielinska, M

    2012-01-01

    The neutron-rich nuclei $^{94,96}$Kr were studied via projectile Coulomb excitation at the REX-ISOLDE facility at CERN. Level energies of the first excited 2$^{+}$ states and their absolute $E2$ transition strengths to the ground state are determined and discussed in the context of the $E(2^{+}_{1})$ and $B(E2;2^{+}_{1} \\rightarrow 0^{+}_{1})$ systematics of the krypton chain. Contrary to previously published results no sudden onset of deformation is observed. This experimental result is supported by a new proton-neutron interacting boson model calculation based on the constrained Hartree-Fock-Bogoliubov approach using the microscopic Gogny-D1M energy density functional.

  16. Observation of isoscalar and isovector dipole excitations in neutron-rich 20O

    Directory of Open Access Journals (Sweden)

    N. Nakatsuka

    2017-05-01

    Full Text Available The isospin characters of low-energy dipole excitations in neutron-rich unstable nucleus 20O were investigated, for the first time in unstable nuclei. Two spectra obtained from a dominant isovector probe (O20+Au and a dominant isoscalar probe (O20+α were compared and analyzed by the distorted-wave Born approximation to extract independently the isovector and isoscalar dipole strengths. Two known 1− states with large isovector dipole strengths at energies of 5.36(5 MeV (11− and 6.84(7 MeV (12− were also excited by the isoscalar probe. These two states were found to have different isoscalar dipole strengths, 2.70(32% (11− and 0.67(12% (12−, respectively, in exhaustion of the isoscalar dipole-energy-weighted sum rule. The difference in isoscalar strength indicated that they have different underlying structures.

  17. Number projected two-neutron separation energy in the neutron-rich rare-earth region

    International Nuclear Information System (INIS)

    Benhamouda, N.; Oudih, M.R.; Allal, N.H.; Fellah, M.

    2008-01-01

    The variation of the two-neutron separation energy (S 2N ), as a function of the neutron number N, is studied using a microscopic model that includes the pairing effects rigorously within the Fixed-Sharp-BCS method. The model was first tested on "ordinary" nuclei and allowed one to suitably reproduce the experimental data and to confirm the results of previous studies. The model was then applied to the even–even neutron-rich isotopes in the rare-earth region and showed, on the one hand, a relatively important variation of S 2N , when N = 100, that could lead to the assumption of the existence of a new magic number in this region, and on the other hand, a weak variation of S 2N when N > 100. These findings corroborate the previously obtained results for the charge mean square radius and the quadrupole and hexadecapole moments within the same model. (author)

  18. Determination of spin, magnetic moment and isotopic shift of neutron rich 205Hg by optical pumping

    International Nuclear Information System (INIS)

    Rodriguez, J.; Bonn, J.; Huber, G.; Kluge, H.J.; Otten, E.W.; European Organisation for Nuclear Research, Geneva

    1975-01-01

    Neutron rich 205 Hg(Tsub(1/2) = 5.2 min) was produced and on-line mass separated at the ISOLDE facility at CERN. The polarization achieved by optical pumping via the atomic line (6s 21 S 0 - 6s6p 3 P 1 , lambda = 2,537 A) was monitored by the β decay asymmetry. Hyperfine structure and isotopic shift of the 205 Hg absorption line was determined by Zeeman scanning. In addition a magnetic resoncance was performed on the polarized 205 Hg nuclei in the atomic ground state. The results are: I( 205 Hg) = 1/2 (confirmed); μ(I, 205 Hg) = 0.5915(1)μ(N) (uncorrected for diamagnetism); isotopic shift deltaν(204/205) = ν( 205 Hg) - ν( 204 Hg) = -1.8(1)GHz. μ(I) and IS are discussed briefly in the frame of current literature. (orig.) [de

  19. Study of the structure of yrast bands of neutron-rich 114-124Pd isotopes

    Science.gov (United States)

    Chaudhary, Ritu; Devi, Rani; Khosa, S. K.

    2018-02-01

    The projected shell model calculations have been carried out in the neutron-rich 114-124Pd isotopic mass chain. The results have been obtained for the deformation systematics of E(2+1) and E(4+1)/E({2}+1) values, BCS subshell occupation numbers, yrast spectra, backbending phenomena, B( E2) transition probabilities and g-factors in these nuclei. The observed systematics of E(2+1) values and R_{42} ratios in the 114-124Pd isotopic mass chain indicate that there is a decrease of collectivity as the neutron number increases from 68 to 78. The occurrence of backbending in these nuclei as well as the changes in the calculated B( E2) transition probabilities and g -factors predict that there are changes in the structure of yrast bands in these nuclei. These changes occur at the spin where there is crossing of g-band by 2-qp bands. The predicted backbendings and predicted values of B( E2)s and g-factors in some of the isotopes need to be confirmed experimentally.

  20. Experimental study of the lifetime and phase transition in neutron-rich Zr 98 ,100 ,102

    Science.gov (United States)

    Ansari, S.; Régis, J.-M.; Jolie, J.; Saed-Samii, N.; Warr, N.; Korten, W.; Zielińska, M.; Salsac, M.-D.; Blanc, A.; Jentschel, M.; Köster, U.; Mutti, P.; Soldner, T.; Simpson, G. S.; Drouet, F.; Vancraeyenest, A.; de France, G.; Clément, E.; Stezowski, O.; Ur, C. A.; Urban, W.; Regan, P. H.; Podolyák, Zs.; Larijani, C.; Townsley, C.; Carroll, R.; Wilson, E.; Mach, H.; Fraile, L. M.; Paziy, V.; Olaizola, B.; Vedia, V.; Bruce, A. M.; Roberts, O. J.; Smith, J. F.; Scheck, M.; Kröll, T.; Hartig, A.-L.; Ignatov, A.; Ilieva, S.; Lalkovski, S.; Mǎrginean, N.; Otsuka, T.; Shimizu, N.; Togashi, T.; Tsunoda, Y.

    2017-11-01

    Rapid shape changes are observed for neutron-rich nuclei with A around 100. In particular, a sudden onset of ground-state deformation is observed in the Zr and Sr isotopic chains at N = 60: Low-lying states in N ≤58 nuclei are nearly spherical, while those with N ≥60 have a rotational character. Nuclear lifetimes as short as a few picoseconds can be measured using fast-timing techniques with LaBr3(Ce) scintillators, yielding a key ingredient in the systematic study of the shape evolution in this region. We used neutron-induced fission of 241Pu and 235U to study lifetimes of excited states in fission fragments in the A ˜100 region with the EXILL-FATIMA array located at the PF1B cold neutron beam line at the Institut Laue-Langevin. In particular, we applied the generalized centroid difference method to deduce lifetimes of low-lying states for the nuclei 98Zr (N = 58), 100Zr, and 102Zr (N ≥60 ). The results are discussed in the context of the presumed phase transition in the Zr chain by comparing the experimental transition strengths with the theoretical calculations using the interacting boson model and the Monte Carlo shell model.

  1. Coulomb excitation of neutron-rich odd-$A$ Cd isotopes

    CERN Multimedia

    Reiter, P; Kruecken, R; Gernhaeuser, R A; Kroell, T; Leske, J; Marginean, N M

    We propose to study excited states in the odd-${A}$ isotopes $^{123,125,127}$Cd by ${\\gamma}$-ray spectroscopy following "safe" Coulomb excitation. The experiment aims to determine the B(E2) values connecting excited states with the ground state as well as the long-lived (11/2$^{-}$) isomer. The proposed study profits from the unique capability of ISOLDE to produce beams containing Cd in the ground state or in the isomeric state. Our recent results on the neutron-rich even-A Cd nuclei appear to show that these nuclei may possess some collectivity beyond that calculated by modern shell-model predictions. Beyond-mean-field calculations also predict these nuclei to be weakly deformed. These facets are surprising considering their proximity to the doubly magic $^{132}$Sn. Coulomb-excitation studies of odd-${A}$ Cd isotopes may give a unique insight into the deformation-driving roles played by different orbits in this region. Such studies of the onset of collectivity become especially important in light of recent...

  2. Emergence of low-energy monopole strength in the neutron-rich calcium isotopes

    Science.gov (United States)

    Piekarewicz, J.

    2017-10-01

    Background: The isoscalar monopole response of neutron-rich nuclei is sensitive to both the incompressibility coefficient of symmetric nuclear matter and the density dependence of the symmetry energy. For exotic nuclei with a large neutron excess, a low-energy component emerges that is driven by transitions into the continuum. Purpose: While understanding the scaling of the giant monopole resonance with mass number is central to this work, the main goal of this paper is to explore the emergence, evolution, and origin of low-energy monopole strength along the even-even calcium isotopes: from 40Ca to 60Ca. Methods: The distribution of isoscalar monopole strength is computed in a relativistic random phase approximation (RPA) using three effective interactions that have been calibrated to the properties of finite nuclei and neutron stars. A nonspectral approach is adopted that allows for an exact treatment of the continuum without any reliance on discretization. This is particularly critical in the case of weakly bound nuclei with single-particle orbits near the continuum. The discretization of the continuum is neither required nor admitted. Results: For the stable calcium isotopes, no evidence of low-energy monopole strength is observed, even as the 1 f7 /2 neutron orbital is being filled and the neutron-skin thickness progressively grows. Further, in contrast to experimental findings, a mild softening of the monopole response with increasing mass number is predicted. Beyond 48Ca, a significant amount of low-energy monopole strength emerges as soon as the weak-binding neutron orbitals (2 p and 1 f5 /2 ) become populated. The emergence and evolution of low-energy strength is identified with transitions from these weakly bound states into the continuum—which is treated exactly in the RPA approach. Moreover, given that models with a soft symmetry energy tend to reach the neutron-drip line earlier than their stiffer counterparts, an inverse correlation is identified

  3. Schottky mass measurements of heavy neutron-rich nuclides in the element range $70\\leq Z\\leq 79$ at the ESR

    CERN Document Server

    Shubina, D; Litvinov, Yu A; Blaum, K; Brandau, C; Bosch, F; Carroll, J J; Casten, R F; Cullen, D M; Cullen, I J; Deo, A Y; Detwiler, B; Dimopoulou, C; Farinon, F; Geissel, H; Haettner, E; Heil, M; Kempley, R S; Kozhuharov, C; Knobel, R; Kurcewicz, J; Kuzminchuk, N; Litvinov, S A; Liu, Z; Mao, R; Nociforo, C; Nolden, F; Patyk, Z; Plass, W R; Prochazka, A; Reed, M W; Sanjari, M S; Scheidenberger, C; Steck, M; Stohlker, Th; Sun, B; Swan, T P D; Trees, G; Walker, P M; Weick, H; Winckler, N; Winkler, M; Woods, P J; Yamaguchi, T; Zhou, C

    2013-01-01

    Storage-ring mass spectrometry was applied to neutron-rich $^{197}$Au projectile fragments. Masses of $^{181,183}$Lu, $^{185,186}$Hf, $^{187,188}$Ta, $^{191}$W, and $^{192,193}$Re nuclei were measured for the first time. The uncertainty of previously known masses of $^{189,190}$W and $^{195}$Os nuclei was improved. Observed irregularities on the smooth two-neutron separation energies for Hf and W isotopes are linked to the collectivity phenomena in the corresponding nuclei.

  4. Shape transition in the neutron rich sodium isotopes

    International Nuclear Information System (INIS)

    Campi, X.; Flocard, H.; Kerman, A.K.; Koonin, S.; Massachusetts Inst. of Tech., Cambridge

    1975-06-01

    Mass spectrometer measurements of the neutron rich sodium isotopes show a sudden increase at 31 Na in the values of the two neutron separation energies. The spherical shell model naturally predicts a sudden decrease at 32 Na after the N=20 shell closure. It is proposed that the explanation for this disagreement lies in the fact that sodium isotopes in this mass region are strongly deformed due to the filling of negative parity orbitals from the 1fsub(7/2) shell. Hartree-Fock calculations are presented in support of this conjecture [fr

  5. Precision mass measurements for studies of nucleosynthesis via the rapid neutron-capture process Penning-trap mass measurements of neutron-rich cadmium and caesium isotopes

    CERN Document Server

    AUTHOR|(CDS)2085660; Litvinov, Yuri A.; Kreim, Susanne

    Although the theory for the rapid neutron-capture process (r-process) was developed more than 55 years ago, the astrophysical site is still under a debate. Theoretical studies predict that the r-process path proceeds through very neutron-rich nuclei with very asymmetric proton- to-neutron ratios. Knowledge about the properties of neutron-rich isotopes found in similar regions of the nuclear chart and furthermore suitable for r-process studies is still little or even not existing. The basic nuclear properties such as binding energies, half-lives, neutron-induced or neutron-capture reaction cross-sections, play an important role in theoretical simulations and can vary or even drastically alternate results of these studies. Therefore, a considerable effort was put forward to access neutron-rich isotopes at radioactive ion-beam facilities like ISOLDE at CERN. The goal of this PhD thesis is to describe the experimental work done for the precision mass measurements of neutron-rich cadmium (129−131 Cd) and caesium...

  6. Precision mass measurements for studies of nucleosynthesis via the rapid neutron-capture process. Penning-trap mass measurements of neutron-rich cadmium and caesium isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Atanasov, Dinko

    2016-07-06

    Although the theory for the rapid neutron-capture process (r-process) was developed more than 55 years ago, the astrophysical site is still under a debate. Theoretical studies predict that the r-process path proceeds through very neutron-rich nuclei with very asymmetric proton-to-neutron ratios. Knowledge about the properties of neutron-rich isotopes found in similar regions of the nuclear chart and furthermore suitable for r-process studies is still little or even not existing. The basic nuclear properties such as binding energies, half-lives, neutron-induced or neutron-capture reaction cross-sections, play an important role in theoretical simulations and can vary or even drastically alternate results of these studies. Therefore, a considerable effort was put forward to access neutron-rich isotopes at radioactive ion-beam facilities like ISOLDE at CERN. The goal of this PhD thesis is to describe the experimental work done for the precision mass measurements of neutron-rich cadmium ({sup 129-131}Cd) and caesium ({sup 132,146-148}Cs) isotopes. Measurements were done at the on-line radioactive ion-beam facility ISOLDE by using the four-trap mass spectrometer ISOLTRAP. The cadmium isotopes are key nuclides for the synthesis of stable isotopes around the mass peak A = 130 in the Solar System abundance.

  7. Mass measurements of neutron rich isotopes in the Fe region and electron capture processes in neutron star crusts

    International Nuclear Information System (INIS)

    Estrade, Alfredo; Matos, M.; Schatz, Hendrik; Amthor, A.M.; Beard, Mary; Brown, Edward; Bazin, D.; Becerril, A.; Elliot, T.; Gade, A.; Galaviz, D.; Gupta, Sanjib; Hix, William Raphael; Lau, Rita; Moeller, Peter; Pereira, J.; Portillo, M.; Rogers, A.M.; Shapira, Dan; Smith, E.; Stolz, A.; Wallace, M.; Wiescher, Michael

    2011-01-01

    Experimental knowledge of nuclear masses of exotic nuclei is important for understanding nuclear structure far from the valley of stability, and as a direct input into astrophysical models. Electron capture processes in the crust of accreting neutron stars have been proposed as a heat source that can affect the thermal structure of the star. Nuclear masses of very neutron-rich nuclides are necessary inputs to model the electron capture process. The time-of-flight (TOF) mass measurement technique allows measurements on very short-lived nuclei. It has been effectively applied using the fast fragment beams produced at the National Superconducting Cyclotron Lab (NSCL) to reach masses very far from stability. Measurements were performed for neutron-rich isotopes in the region of the N=32 and N=40 subshells, which coincides with the mass range of carbon superburst ashes. We discuss reaction network calculations performed to investigate the impact of our new measurements and to compare the effect of using different global mass models in the calculations. It is observed that the process is sensitive to the differences in the odd-even mass staggering predicted by the mass models, and our new result for 66Mn has a significant impact on the distribution of heat sources in the crust.

  8. Nuclear structure studies of the neutron-rich Rubidium isotopes using Coulomb excitation

    CERN Multimedia

    Reiter, P; Blazhev, A A; Voulot, D; Meot, V H; Simpson, G S; Georgiev, G P; Gaudefroy, L; Roig, O

    We propose to study the properties of odd-mass neutron-rich rubidium isotopes by the Coulomb-excitation technique, using the Miniball array coupled to the REX-ISOLDE facility. The results from similar measurements from the recent years (e.g. for the odd-mass and the odd-odd Cu isotopes, IS435) have shown the strong potential in such measurements for gaining information both for single-particle-like and collective states in exotic nuclei. Since there is practically no experimental information for excited states in the odd-mass Rb isotopes beyond $^{93}$Rb, the present study should be able to provide new data in a region of spherical ($^{93}$Rb and $^{95}$Rb) as well as well-deformed nuclei ($^{97}$Rb and $^{99}$Rb). Of particular interest is the rapid shape change that occurs when going from $^{95}$Rb (${\\varepsilon}_{2}$=0.06) to $^{97}$Rb (${\\varepsilon}_{2}$=0.3). These results should be of significant astrophysical interest as well, due to the close proximity of the r-process path.

  9. Evolution of nuclear structure in neutron-rich odd-Zn isotopes and isomers

    Directory of Open Access Journals (Sweden)

    C. Wraith

    2017-08-01

    Full Text Available Collinear laser spectroscopy was performed on Zn (Z=30 isotopes at ISOLDE, CERN. The study of hyperfine spectra of nuclei across the Zn isotopic chain, N=33–49, allowed the measurement of nuclear spins for the ground and isomeric states in odd-A neutron-rich nuclei up to N=50. Exactly one long-lived (>10 ms isomeric state has been established in each 69–79Zn isotope. The nuclear magnetic dipole moments and spectroscopic quadrupole moments are well reproduced by large-scale shell–model calculations in the f5pg9 and fpg9d5 model spaces, thus establishing the dominant term in their wave function. The magnetic moment of the intruder Iπ=1/2+ isomer in 79Zn is reproduced only if the νs1/2 orbital is added to the valence space, as realized in the recently developed PFSDG-U interaction. The spin and moments of the low-lying isomeric state in 73Zn suggest a strong onset of deformation at N=43, while the progression towards 79Zn points to the stability of the Z=28 and N=50 shell gaps, supporting the magicity of 78Ni.

  10. β-decay spectroscopy of neutron-rich 160,161,162Sm isotopes

    Directory of Open Access Journals (Sweden)

    Patel Z.

    2016-01-01

    Full Text Available Neutron-rich 160,161,162Sm isotopes have been populated at the RIBF, RIKEN via β first time. β-coincident γ rays were observed in all three isotopes including γ rays from the isomeric decay of 160Sm and 162Sm. The isomers in 160Sm and 162Sm have previously been observed but have been populated via β decay for the first time. The isomeric state in 162Sm is assigned a 4−v72+[ 633 ]⊗v12−[ 521 ]${4^ - }v{{7 \\over 2}^ + }\\left[ {633} \\right] \\otimes v{{1 \\over 2}^ - }\\left[ {521} \\right]$ configuration based on the decay pattern. The level schemes of 160Sm and 162Sm are presented. The ground states in the parent nuclei 160Pm and 162Pm are both assigned a 6−v72+[633]⊗π52−[532]${6^ - }v{{7 \\over 2}^ + }\\left[ {633} \\right] \\otimes \\pi {{5 \\over 2}^ - }\\left[ {532} \\right]$ configuration based on the population of states in the daughter nuclei. Blocked BCS calculations were performed to further investigate the spin-parities of the ground states in 160Pm, 161Pm, and 162Pm, and the isomeric state in 162Sm

  11. Neutron-rich polonium isotopes studied with in-source laser spectroscopy

    CERN Document Server

    Dexters, Wim; Cocolios, T E

    This work studies the unknown region of neutron rich polonium isotopes. The polonium isotopes, with Z=84, lie above the magic lead nuclei (Z=82). The motivation for this research can mainly be found in these lead nuclei. When looking at the changes in the mean square charge radii beyond the N=126 shell gap, a kink is observed. This kink is also found in the radon (Z=86) and radium (Z=88) isotopes. The observed effect cannot be reproduced with our current models. The polonium isotopes yield more information on the kink and they are also able to link the known charge radii in lead isotopes to those in radon and radium. Additionally, the nuclear moments of the odd-neutron isotope $^{211}$Po are investigated. This nucleus has two protons and one neutron more than the doubly magic nucleus $^{208}$Pb. Nuclear moments of isotopes close to this doubly magic nucleus are good tests for the theoretic models. Besides pushing the models to their limits, the nuclear moments of $^{211}$Po also yield new information on the f...

  12. Study of Ground State Wave-function of the Neutron-rich 29,30Na Isotopes through Coulomb Breakup

    Directory of Open Access Journals (Sweden)

    Rahaman A.

    2014-03-01

    Full Text Available Coulomb breakup of unstable neutron rich nuclei 29,30Na around the ‘island of inversion’ has been studied at energy around 434 MeV/nucleon and 409 MeV/nucleon respectively. Four momentum vectors of fragments, decay neutron from excited projectile and γ-rays emitted from excited fragments after Coulomb breakup are measured in coincidence. For these nuclei, the low-lying dipole strength above one neutron threshold can be explained by direct breakup model. The analysis for Coulomb breakup of 29,30Na shows that large amount of the cross section yields the 28Na, 29Na core in ground state. The predominant ground-state configuration of 29,30Na is found to be 28Na(g.s⊗νs1/2 and 29Na(g.s⊗νs1/2,respectively.

  13. ISOL Beams of Neutron-Rich Oxygen Isotopes

    CERN Document Server

    Köster, U; Bergmann, U; Catherall, R; Cederkäll, J; Dillmann, I; Dubois, M; Durantel, F; Fraile-Prieto, L M; Franchoo, S; Gaubert, G; Gaudefroy, L; Hallmann, O; Huet-Equilbec, C; Jacquot, B; Jardin, P; Kratz, K L; Lecesne, N; Leroy, R; López, A; Maunoury, L; Pacquet, J Y; Pfeiffer, B; Saint-Laurent, M G; Stodel, C; Villari, A C C; Weissman, L

    2005-01-01

    ISOL beams of $19-22^$O were produced at ISOLDE and GANIL. At ISOLDE the neutron-rich oxygen isotopes are produced by 1.4GeV proton-induced reactionsin a UC_X/graphite target. The target is connected via a water-cooled transfer line (to retain all non-volatile isobars) to an ISOLDE type FEBIAD ion source wherethe released CO is dominantly ionized as CO^+, $^19-22$O beams were also produced at SPIRAL (GANIL). A 77.5 MeV/nucleon $^36$S beam was fragmented in a thick graphite target, coupled by a cold tranfer tube to an ECR ion source which ionizes the released CO dominantly as O^+ and CO+.

  14. Beta-decay half-lives for the r-process nuclei

    International Nuclear Information System (INIS)

    Panov, I.V.; Lutostansky, Yu.S.; Thielemann, F.-K.

    2016-01-01

    For nucleosynthesis calculations of the r-process it is important to know beta-decay half-lives of short-lived neutron-rich nuclei. In the present paper these characteristics are calculated for an extended number of neutron-rich nuclei, important for the r-process. In our calculations the model description of beta-strength functions based on Finite Fermi-Systems Theory is used. The comparison with other predictions and experimental data is done. It is shown that the accuracy of beta-decay half-lives of short-lived neutron-rich nuclei is increasing with increasing neutron excess and can be used for modeling of nucleosynthesis of heavy nuclei in the r-process. For nuclei heavier than lead the half-lives of neutron-rich nuclei are on average 10 times smaller, than proposed of other predictions.

  15. Microscopic multiphonon approach to spectroscopy in the neutron-rich oxygen region

    Science.gov (United States)

    De Gregorio, G.; Knapp, F.; Lo Iudice, N.; Veselý, P.

    2018-03-01

    Background: A fairly rich amount of experimental spectroscopic data have disclosed intriguing properties of the nuclei in the region of neutron rich oxygen isotopes up to the neutron dripline. They, therefore, represent a unique laboratory for studying the evolution of nuclear structure away from the stability line. Purpose: We intend to give an exhaustive microscopic description of low and high energy spectra, dipole response, weak, and electromagnetic properties of the even 22O and the odd 23O and 23F. Method: An equation of motion phonon method generates an orthonormal basis of correlated n -phonon states (n =0 ,1 ,2 ,⋯ ) built of constituent Tamm-Dancoff phonons. This basis is adopted to solve the full eigenvalue equations in even nuclei and to construct an orthonormal particle-core basis for the eigenvalue problem in odd nuclei. No approximations are involved and the Pauli principle is taken into full account. The method is adopted to perform self-consistent, parameter free, calculations using an optimized chiral nucleon-nucleon interaction in a space encompassing up to two-phonon basis states. Results: The computed spectra in 22O and 23O and the dipole cross section in 22O are in overall agreement with the experimental data. The calculation describes poorly the spectrum of 23F. Conclusions: The two-phonon configurations play a crucial role in the description of spectra and transitions. The large discrepancies concerning the spectra of 23F are ultimately traced back to the large separation between the Hartree-Fock levels belonging to different major shells. We suggest that a more compact single particle spectrum is needed and can be generated by a new chiral potential which includes explicitly the contribution of the three-body forces.

  16. Mean-field models and exotic nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Bender, M.; Buervenich, T.; Maruhn, J.A.; Greiner, W. [Inst. fuer Theoretische Physik, Univ. Frankfurt (Germany); Rutz, K. [Inst. fuer Theoretische Physik, Univ. Frankfurt (Germany)]|[Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Reinhard, P.G. [Inst. fuer Theoretische Physik, Univ. Erlangen (Germany)

    1998-06-01

    We discuss two widely used nuclear mean-field models, the relativistic mean-field model and the (nonrelativistic) Skyrme-Hartree-Fock model, and their capability to describe exotic nuclei. Test cases are superheavy nuclei and neutron-rich Sn isotopes. New information in this regime helps to fix hitherto loosely determined aspects of the models. (orig.)

  17. Mean-field models and exotic nuclei

    International Nuclear Information System (INIS)

    Bender, M.; Buervenich, T.; Maruhn, J.A.; Greiner, W.; Rutz, K.; Reinhard, P.G.

    1998-01-01

    We discuss two widely used nuclear mean-field models, the relativistic mean-field model and the (nonrelativistic) Skyrme-Hartree-Fock model, and their capability to describe exotic nuclei. Test cases are superheavy nuclei and neutron-rich Sn isotopes. New information in this regime helps to fix hitherto loosely determined aspects of the models. (orig.)

  18. Experiments with relativistic exotic nuclei at the FRS

    International Nuclear Information System (INIS)

    Geissel, H.

    1994-11-01

    The concept and experimental programme of the secondary nuclear beam facility BRENDA at GSI is presented. The central part of BRENDA is the magnetic spectrometer FRS providing spatially separated monoisotopic exotic beams of all elements up to uranium. The FRS as a versatile magnetic spectrometer for experiments with heavy ions in the energy range of (0.1-2) A.GeV has been used to study peripheral nuclear collisions from oxygen up to uranium projectiles. In the uranium experiments we discovered that projectile fission is a powerful tool to investigate new neutron-rich fission fragments. In the medium mass region we have identified the doubly magic nucleus 100 Sn and measured its half-life. Light halo nuclei have been studied in kinematically complete experiments with the FRS in combination with the dipole magnet ALADIN, and the neutron detector LAND. The FRS combined with the storage and cooler ring ESR offers new precision experiments, e.g., direct mass measurements, decay studies of highly-charged nuclei, or nuclear structure studies in inverse kinematics. (orig.)

  19. Nuclear-decay studies of neutron-rich rare-earth nuclides

    International Nuclear Information System (INIS)

    Chasteler, R.M.

    1990-01-01

    Neutron-rich rare-earth nuclei were produced in multinucleon transfer reactions of 170 Er and 176 Yb projectiles on nat W targets at the Lawrence Berkeley Laboratory SuperHILAC and their radioactive decays properties studied at the on-line mass separation facility OASIS. Two unknown isotopes, 169 Dy (t 1/2 = 39 ± 8 s) and 174 Er(t 1/2 = 3.3 ± 0.2 m) were discovered and their decay characteristics determined. The decay schemes for two previously identified isotopes, 168 Dy (t 1/2 = 8.8 ± 0.3 m) and 171 Ho (t 1/2 = 55 ± 3 s), were characterized. Evidence for a new isomer of 3.0 m 168 Ho g , 168 Ho m (t 1/2 = 132 ± 4 s) which decays by isomeric transition (IT) is presented. Beta particle endpoint energies were determined for the decay of 168 Ho g , 169 Dy, 171 Ho, and 174 Er, the resulting Qβ-values are: 2.93 ± 0.03, 3.2 ± 0.3, 3.2 ± 0.6, and 1.8 ± 0.2 MeV, respectively. These values were compared with values calculated using recent atomic mass formulae. Comparisons of various target/ion source geometries used in the OASIS mass separator facility for these multinucleon transfer reactions were performed. 73 refs., 40 figs., 11 tabs

  20. Signatures of octupole correlations in neutron-rich odd-mass barium isotopes

    Science.gov (United States)

    Nomura, K.; Nikšić, T.; Vretenar, D.

    2018-02-01

    Octupole deformation and the relevant spectroscopic properties of neutron-rich odd-mass barium isotopes are investigated in a theoretical framework based on nuclear density functional theory and the particle-core coupling scheme. The interacting-boson Hamiltonian that describes the octupole-deformed even-even core nucleus, as well as the single-particle energies and occupation probabilities of an unpaired nucleon, are completely determined by microscopic axially symmetric (β2,β3) -deformation constrained self-consistent mean-field calculations for a specific choice of the energy density functional and pairing interaction. A boson-fermion interaction that involves both quadrupole and octupole degrees of freedom is introduced, and their strength parameters are determined to reproduce selected spectroscopic data for the odd-mass nuclei. The model reproduces recent experimental results for both even-even and odd-mass Ba isotopes. In particular, for Ba,147145 our results indicate, in agreement with recent data, that octupole deformation does not determine the structure of the lowest states in the vicinity of the ground state, and only becomes relevant at higher excitation energies.

  1. Evolution of Single Particle and Collective properties in the Neutron-Rich Mg Isotopes

    CERN Multimedia

    Reiter, P; Wiens, A; Fitting, J; Lauer, M; Van duppen, P L E; Finke, F

    2002-01-01

    We propose to study the single particle and collective properties of the neutron-rich Mg isotopes in transfer reactions and Coulomb excitation using REX-ISOLDE and MINIBALL. From the Coulomb excitation measurement precise and largely model independent B( E2 ; 0$^{+}_{g.s.}\\rightarrow$ 2$^{+}_{1}$ ) will be determined for the even-even isotopes. For the odd isotopes the distribution of the E2 strength over a few low-lying states will be measured. The sign of the M1/E2 mixing ratio, extracted from angular distributions, is characteristic of the sign of the deformation, as is the resulting level scheme. The neutron-pickup channel in the transfer reactions will allow for a determination of the single particle properties (spin, parity, spectroscopic factors) of these nuclei. This information will give new insights in changes of nuclear structure in the vicinity of the island of deformation around $^{32}$Mg. A total of 24 shifts of REX beam time is requested.

  2. Shape coexistence in neutron-rich Sr isotopes : Coulomb excitation of $^{96}$Sr

    CERN Document Server

    Clement, E; Siem, S; Czosnyka, T

    2007-01-01

    The nuclei in the mass region A $\\cong$ 100 around Sr and Zr show a dramatic change of the nuclear ground-state shape from near spherical for N $\\leq$ 58 to strongly deformed for N $\\geq$ 60. Theoretical calculations predict the coexistence of slightly oblate and strongly prolate deformed configurations in the transitional region. However, excited rotational structures based on the highly deformed configuration, which becomes the ground state at N = 60, are not firmly established in the lighter isotopes, and the earlier interpretation of a very abrupt change of shape has been challenged by recent experimental results in favor of a rather gradual change. We propose to study the electromagnetic properties of the neutron-rich nucleus $_{38}^{96}$Sr$_{58}$ by low-energy Coulomb excitation using the REX-ISOLDE facility and the MINIBALL detector array. Both transitional and diagonal matrix elements will be extracted, resulting in a complete description of the transition strengths and quadrupole moments of the low-l...

  3. Unexpectedly large charge radii of neutron-rich calcium isotopes

    CERN Document Server

    Garcia Ruiz, R F; Blaum, K; Ekström, A; Frömmgen, N; Hagen, G; Hammen, M; Hebeler, K; Holt, J D; Jansen, G R; Kowalska, M; Kreim, K; Nazarewicz, W; Neugart, R; Neyens, G; Nörtershäuser, W; Papenbrock, T; Papuga, J; Schwenk, A; Simonis, J; Wendt, K A; Yordanov, D T

    2016-01-01

    Despite being a complex many-body system, the atomic nucleus exhibits simple structures for certain ‘magic’ numbers of protons and neutrons. The calcium chain in particular is both unique and puzzling: evidence of doubly magic features are known in 40,48Ca, and recently suggested in two radioactive isotopes, 52,54Ca. Although many properties of experimentally known calcium isotopes have been successfully described by nuclear theory, it is still a challenge to predict the evolution of their charge radii. Here we present the first measurements of the charge radii of 49,51,52Ca, obtained from laser spectroscopy experiments at ISOLDE, CERN. The experimental results are complemented by state-of-the-art theoretical calculations. The large and unexpected increase of the size of the neutron-rich calcium isotopes beyond N = 28 challenges the doubly magic nature of 52Ca and opens new intriguing questions on the evolution of nuclear sizes away from stability, which are of importance for our understanding of neutron-...

  4. Transition probabilities in neutron-rich Se,8684

    Science.gov (United States)

    Litzinger, J.; Blazhev, A.; Dewald, A.; Didierjean, F.; Duchêne, G.; Fransen, C.; Lozeva, R.; Sieja, K.; Verney, D.; de Angelis, G.; Bazzacco, D.; Birkenbach, B.; Bottoni, S.; Bracco, A.; Braunroth, T.; Cederwall, B.; Corradi, L.; Crespi, F. C. L.; Désesquelles, P.; Eberth, J.; Ellinger, E.; Farnea, E.; Fioretto, E.; Gernhäuser, R.; Goasduff, A.; Görgen, A.; Gottardo, A.; Grebosz, J.; Hackstein, M.; Hess, H.; Ibrahim, F.; Jolie, J.; Jungclaus, A.; Kolos, K.; Korten, W.; Leoni, S.; Lunardi, S.; Maj, A.; Menegazzo, R.; Mengoni, D.; Michelagnoli, C.; Mijatovic, T.; Million, B.; Möller, O.; Modamio, V.; Montagnoli, G.; Montanari, D.; Morales, A. I.; Napoli, D. R.; Niikura, M.; Pollarolo, G.; Pullia, A.; Quintana, B.; Recchia, F.; Reiter, P.; Rosso, D.; Sahin, E.; Salsac, M. D.; Scarlassara, F.; Söderström, P.-A.; Stefanini, A. M.; Stezowski, O.; Szilner, S.; Theisen, Ch.; Valiente Dobón, J. J.; Vandone, V.; Vogt, A.

    2015-12-01

    Reduced quadrupole transition probabilities for low-lying transitions in neutron-rich Se,8684 are investigated with a recoil distance Doppler shift (RDDS) experiment. The experiment was performed at the Istituto Nazionale di Fisica Nucleare (INFN) Laboratori Nazionali di Legnaro using the Cologne Plunger device for the RDDS technique and the AGATA Demonstrator array for the γ -ray detection coupled to the PRISMA magnetic spectrometer for an event-by-event particle identification. In 86Se the level lifetime of the yrast 21+ state and an upper limit for the lifetime of the 41+ state are determined for the first time. The results of 86Se are in agreement with previously reported predictions of large-scale shell-model calculations using Ni78-I and Ni78-II effective interactions. In addition, intrinsic shape parameters of lowest yrast states in 86Se are calculated. In semimagic 84Se level lifetimes of the yrast 41+ and 61+ states are determined for the first time. Large-scale shell-model calculations using effective interactions Ni78-II, JUN45, jj4b, and jj4pna are performed. The calculations describe B (E 2 ;21+→01+) and B (E 2 ;61+→41+) fairly well and point out problems in reproducing the experimental B (E 2 ;41+→21+) .

  5. Low-lying level structure of the neutron-rich nucleus {sup 109}Nb: A possible oblate-shape isomer

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, H., E-mail: hiroshi@ribf.riken.j [RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Sumikama, T. [Department of Physics, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba (Japan); Nishimura, S. [RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Yoshinaga, K. [Department of Physics, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba (Japan); Li, Z. [RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Miyashita, Y. [Department of Physics, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba (Japan); Yamaguchi, K. [Department of Physics, Osaka University, Machikaneyama-machi 1-1, Osaka 560-0043 Toyonaka (Japan); Baba, H. [RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Berryman, J.S. [Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Blasi, N. [INFN, Sezione di Milano, via Celoria 16, I-20133 Milano (Italy); Bracco, A.; Camera, F. [INFN, Sezione di Milano, via Celoria 16, I-20133 Milano (Italy); Dipartimento di Fisica, Universita di Milano, via Celoria 16, I-20133 Milano (Italy); Chiba, J. [Department of Physics, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba (Japan); Doornenbal, P. [RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Go, S.; Hashimoto, T.; Hayakawa, S. [Center for Nuclear Study, University of Tokyo, Hirosawa 2-1, Wako, Saitama 351-0198 (Japan); Hinke, C. [Physik Department, Technische Universitaet Muenchen, D-85748 Garching (Germany); Ideguchi, E. [Center for Nuclear Study, University of Tokyo, Hirosawa 2-1, Wako, Saitama 351-0198 (Japan); Isobe, T. [RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan)

    2011-01-31

    The neutron-rich nuclei {sup 109}Nb and {sup 109}Zr have been populated using in-flight fission of a {sup 238}U beam at 345 MeV/nucleon at the RIBF facility. A T{sub 1/2}=150(30) ns isomer at 313 keV has been identified in {sup 109}Nb for the first time. The low-lying levels in {sup 109}Nb have been also populated following the {beta}-decay of {sup 109}Zr. Based on the difference in feeding pattern between the isomeric and {beta} decays, the decay scheme from the isomeric state in {sup 109}Nb was established. The observed hindrances of the electromagnetic transitions deexciting the isomeric state are discussed in terms of possible shape coexistence. Potential energy surface calculations for single-proton configurations predict the presence of low-lying oblate-deformed states in {sup 109}Nb.

  6. Shape coexistence close to N = 50 in the neutron-rich isotope 80Ge investigated by IBM-2

    Science.gov (United States)

    Zhang, Da-Li; Mu, Cheng-Fu

    2018-02-01

    The properties of the low-lying states, especially the relevant shape coexistence in 80Ge, close to one of most neutron-rich doubly magic nuclei at N = 50 and Z = 28, have been investigated within the framework of the proton-neutron interacting model (IBM-2). Based on the fact that the relative energy of the d neutron boson is different from that of the proton boson, the calculated energy levels of low-lying states and E2 transition strengths can reproduce the experimental data very well. Particularly, the first excited state {0}2+, which is intimately related to the shape coexistence phenomenon, is reproduced quite nicely. The {ρ }2(E0,{0}2+\\to {0}1+) transition strength is also predicted. The experimental data and theoretical results indicate that both collective spherical and γ-soft vibration structures coexist in 80Ge. Supported by National Natural Science Foundation of China (11475062, 11647306, 11147148)

  7. Production cross section of neutron-rich Pb and Bi isotopes in the fragmentation of 238U

    CERN Document Server

    Alvarez-Pol, H; Benlliure, J; Casarejos, E; Cortina-GilL, D; Napolitani, P; Enqvist, T; Schmidt, K-H; Yordanov, O; Junghans, A.R; Fernández, B; Pereira, P; Jurado, B; Rejmund, F; 10.1140/epja/i2009-10856-8

    Neutron-rich lead and bismuth isotopes have been produced by cold-fragmentation reactions induced by 238U projectiles at 1 AGeV impinging on a beryllium target. The high-resolving power FRagment Separator at GSI allowed us to identify and determine the production cross sections of 22 nuclei, nine of them for the first time 215Pb, 216Pb, 217Pb, 218Pb and 217Bi, 218Bi, 219Bi, 220Bi, 221Bi, 222Bi. These data are compared to other previously measured cross sections in similar reactions and model calculations. The validation of the codes is of utmost importance for estimating of the new limits accessible with the new generation radioactive beam facilities.

  8. Shape coexistence in neutron-rich Sr isotopes : Coulomb excitation of 98Sr

    NARCIS (Netherlands)

    Clément, E; Görgen, A.; Korten, W.; Walle J. van de, [No Value

    2010-01-01

    In this addendum we ask for beam time to perform Coulomb excitation of 98Sr in order to complete our program on the study of shape coexistence and evolution of collectivity in neutron rich strontium isotopes at N=60.

  9. K isomerism and collectivity in neutron-rich rare-earth isotopes

    Science.gov (United States)

    Patel, Zena

    Neutron-rich rare-earth isotopes were produced by in-flight fission of 238U ions at the Radioactive Isotope Beam Factory (RIBF), RIKEN, Japan. In-flight fission of a heavy, high-intensity beam of 238U ions on a light target provides the cleanest secondary beams of neutron-rich nuclei in the rare-earth region of isotopes. In-flight fission is advantageous over other methods of nuclear production, as it allows for a secondary beam to be extracted, from which the beam species can be separated and identified. The excited states of nuclei are studied by delayed isomeric or beta-delayed gamma-ray spectroscopy. New K isomers were found in Sm (Z=62), Eu (Z=63), and Gd (Z=64) isotopes. The key results are discussed here. Excited states in the N=102 isotones 166Gd and 164Sm have been observed following isomeric decay for the first time. The K-isomeric states in 166Gd and 164Sm are due to 2-quasiparticle configurations. Based on the decay patterns and potential energy surface calculations, including beta6 deformation, both isomers are assigned a (6-) spin-parity. The half-lives of the isomeric states have been measured to be 950(60)ns and 600(140)ns for 166Gd and 164Sm respectively. Collective observables are discussed in light of the systematics of the region, giving insight into nuclear shape evolution. The decrease in the ground state band energies of 166Gd and 164Sm (N=102) compared to 164Gd and 162Sm (N=100) respectively, presents evidence for the predicted deformed shell closure at N=100. A 4-quasiparticle isomeric state has been discovered in 160Sm: the lightest deformed nucleus with a 4-quasiparticle isomer to date. The isomeric state is assigned an (11+) spin-parity with a measured half-life of 1.8(4)us. The (11+) isomeric state decays into a rotational band structure, based on a (6-) v5/2-[523] ⊗ v7/2+[633] bandhead, determined from the extracted gK-gR values. Potential energy surface and blocked BCS calculations were performed in the deformed midshell region

  10. Study of the elastic scattering and of the (p,n) charge exchange reaction with neutron-rich light exotic beams

    International Nuclear Information System (INIS)

    Cortina Gil, D.

    1996-01-01

    We have measured at GANIL, with the high resolution spectrometer SPEG, the elastic scattering of several neutron rich secondary beams ( 6 He, 10 Be and 11 Be) on a polypropylene target and the charge exchange reaction p( 6 He, 6 Li)n. These exotic beams were produced by nuclear fragmentation and re-focalized with the SISSI device (superconducting solenoids). The signature of a halo structure in these nuclei has been analysed. Special attention has been paid to several aspects of the associated calculations namely, the proton and neutron density distributions and the small binding energy for the last nucleons in these exotic nuclei. Break-up mechanisms are seen to play an important role in these nuclei

  11. Changes in neutron shell closures of light very neutron-rich nuclei

    Czech Academy of Sciences Publication Activity Database

    Dlouhý, Zdeněk; Angéligue, J. C.; Anne, R.; Auger, G.; Azaiez, F.; Baiborodin, Dmitri; Borcea, C.; Caurier, E.; Gillibert, A.; Grévy, S.; Guillemaud-Mueller, D.; Lalleman, A. S.; Lewitowicz, M.; Lopez-Jimenez, M. J.; Lukyanov, S. M.; Mittig, W.; Mrázek, Jaromír; Mueller, A. C.; Nowacki, F.; Oganessian, Yu. T.; de Oliveira Santos, F.; Orr, N.; Page, R. D.; Penionzhkevich, Y. E.; Pougheon, F.; Reed, A. T.; Ren, Z.; Ridikas, D.; Roussel-Chomaz, P.; Saint Laurent, M. G.; Sakurai, H.; Sarazin, F.; Savajols, H.; Sorlin, O.; Tarasov, O.; Thiamová, Gabriela; de Vismes, A.; Winfield, J.

    2001-01-01

    Roč. 51, - (2001), s. 245-253 ISSN 0011-4626. [Proceedings of the International Workshop "Symmetries and spin". Praha, 17.07.2000-22.07.2000] R&D Projects: GA AV ČR IAA1048102 Institutional research plan: CEZ:AV0Z1048901 Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 0.345, year: 2001

  12. New neutron magic number N=16 for neutron-rich nuclei

    Czech Academy of Sciences Publication Activity Database

    Dlouhý, Zdeněk; Baiborodin, Dmitri; Mrázek, Jaromír; Thiamová, Gabriela

    2003-01-01

    Roč. 66, č. 8 (2003), s. 1536-1543 ISSN 1063-7788 R&D Projects: GA AV ČR IAA1048102 Institutional research plan: CEZ:AV0Z1048901 Keywords : neutron magic number N =16 Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 0.467, year: 2003

  13. Alpha decay and cluster decay of some neutron-rich actinide nuclei

    Indian Academy of Sciences (India)

    Our model has a cubic potential for the overlapping region which is smoothly connected by a Yukawa plus exponential potential for the region after separation. The computed half-lives are compared with those of other theoretical models and are found to be in good agreement with each other. In this work, we have also ...

  14. Alpha decay and cluster decay of some neutron-rich actinide nuclei

    Indian Academy of Sciences (India)

    2017-02-09

    Feb 9, 2017 ... plus Yukawa plus exponential model (CYEM). Our model has a cubic potential for the overlapping region which is smoothly connected by a Yukawa plus exponential potential for the region after separation. The computed half-lives are compared with those of other theoretical models and are found to be in ...

  15. Excitation of pygmy dipole resonance in neutron-rich nuclei via ...

    Indian Academy of Sciences (India)

    Author Affiliations. A Vitturi1 E G Lanza2 M V Andrés3 F Catara2 D Gambacurta2. Dipartimento di Fisica and INFN, Padova, Italy; Dipartimento di Fisica and INFN, Catania, Italy; Departamento de FAMN, Facultad de F ́ısica, Sevilla, Spain ...

  16. Soft dipole mode of neutron-rich light nuclei in asymptotic potential approximation

    International Nuclear Information System (INIS)

    Filippov, G.F.; Lashko, Yu.A.; Shvedov, L.P.

    2000-01-01

    Completely antisymmetrized 1''-continuum wave functions as well as the ground state wave function for ''6He have been constructed in asymptotic potential approximation. The behaviour of two-channel S-matrix elements shows on the existence of 1''- resonant state just above the three-body decay threshold of ''6He

  17. In-beam γ-ray spectroscopy of the neutron rich 39Si

    International Nuclear Information System (INIS)

    Sohler, D.; Dombradi, Zs.; Achouri, N.L.; Angelique, J.C.; Bastin, B.; Azaiez, F.; Baiborodin, D.; Borcea, R.

    2009-01-01

    Complete text of publication follows. In order to clarify the role of proton excitations across the Z = 14 subshell closure in neutron-rich Si isotopes, we investigated the structure of the 14 39 Si 25 isotope, having three neutron-hole configurations with respect to an N = 28 core. The excited states of 39 Si were studied by in-beam γ-ray spectroscopy trough fragmentation of radioactive beams. The experiment was performed at the GANIL facility in France. The radioactive beams were produced by the fragmentation of the stable 48 Ca beam of 60 MeV/u energy and 4μA intensity on a 12 C target in the SISSI device. The cocktail beam produced was impinged onto a 9 Be target. The nuclei produced in the secondary fragmentation reaction were selected and unambiguously identified by the SPEG spectrometer. In the performed experiment the 39 Si nuclei were obtained via 1p, 1p1n, 2p1n and 2p2n knockout reactions from the 40,41 P and 42,43 S secondary beams. To measure the γ rays emitted from the excited states, the secondary target was surrounded by the 4π 'Chateau de Crystal' array consisting of 74 BaF 2 scintillators. The γ-ray spectra were generated by gating event-by-event on the incoming secondary beam particles and the ejectiles after the secondary target. For the γ rays emitted by the fast moving fragments accurate Doppler correction was performed. From the obtained γ spectra of 39 Si displayed in Figure 1, two strong γ transitions at 163 and 397 keV as well as weaker ones at 303, 657, 906, 1143 and 1551 keV have been identified. γγ coincidences were obtained in 39 Si after having added all data from the various reaction channels giving rise to 39 Si. Analysing these data the 163 keV transition was found to be in coincidence with the 657, 1143 and 1551 keV ones, but not with the 397 keV transition. The two lines of the 303+397 keV doublet are in mutual coincidence, and one or both of them are found in coincidence with the 906 keV transition.

  18. Probing the collectivity in neutron-rich Cd isotopes via γ-ray spectroscopy

    International Nuclear Information System (INIS)

    Naqvi, Farheen

    2011-01-01

    The spin and configurational structure of excited states of 127 Cd, 125 Cd and 129 Cd, having two proton and three, five and one neutron holes, respectively in the doubly magic 132 Sn core have been studied. The isomeric states in Cd isotopes were populated in the fragmentation of a 136 Xe beam at an energy of 750 MeV/u on a 9 Be target of 4 g/cm 2 . The experiment was performed at GSI Darmstadt. The neutron-rich Cd isotopes were selected using the Bρ - ΔE - Bρ method at the FRagment Separator (FRS). Event by event identification of fragments in terms of their A (mass) and Z (charge) was provided by the standard FRS detectors. The reaction residues were implanted in a plastic stopper surrounded by 15 Ge cluster detectors from the RISING array to detect the γ decays. In 127 Cd, an isomeric state with a half-life of 17.5(3) μs has been detected. This yrast (19/2) + isomer is proposed to have mixed proton-neutron configurations and to decay by two competing stretched M2 and E3 transitions. Experimental results are compared with the isotone 129 Sn. In 125 Cd, apart from the previously observed (19/2) + isomer, two new metastable states at 3896 keV and 2141 keV have been detected. A half-life of 13.6(2) μs was measured for the (19/2) + isomer, having a decay structure similar to the corresponding isomeric state in 127 Cd. The higher lying isomers have a half-life of 3.1(1) μs and 2.5(15) ns, respectively. Time distributions of delayed γ transitions and γγ-coincidence relations were exploited to construct decay schemes for the two nuclei. Comparison of the experimental data with shell-model calculations is also discussed. The new information provides input for the proton-neutron interaction in nuclei around the doubly magic 132 Sn core. The γ decays of the isomeric states in 129 Cd were not observed experimentally. The reasons for the non-observation of delayed γ rays for 129 Cd are either an isomeric half-life of less than 93 ns based on the experimentally

  19. Gamma-ray Spectroscopy of Nano-second Isomers in Neutron-rich Ni Region Produced by Deep-inelastic Collisions

    Science.gov (United States)

    Ishii, Tetsuro; Asai, Masato; Kleinheinz, Peter; Matsuda, Makoto; Ichikawa, Shinichi; Makishima, Akiyasu; Ogawa, Masao

    2001-10-01

    We have been studying nuclear structure of neutron-rich nuclei produced by heavy-ion deep-inelastic collisions at the JAERI Tandem Booster facility. In our method using an `isomer-scope', γ-rays only from isomers with T_1/2 > 1ns are measured by shielding Ge detectors from prompt γ rays emitted at the target position. Atomic numbers of isomers can be also identified by detecting projectile-like fragments with Si Δ E-E detectors. Until now, we have found several new isomers in neutron-rich Ni region using about 8 MeV/nucleon ^70Zn, ^76Ge and ^82Se beams and a ^198Pt target of 4.3 mg/cm^2 thickness. In the doubly magic ^68_28Ni_40, the (ν g_9/2^2 ν p_1/2-2)8^+ isomer with T_1/2=23(1) ns was found. In its neighbor nuclei ^69,71Cu, the 19/2^- isomers were found and the energy levels decaying from the isomers can be calculated very accurately by a parameter-free shell model calculation using experimental energy levels as two-body residual interactions. I will also briefly discuss nano-second isomers in ^32,33Si and ^34P produced by 9 MeV/nucleon ^37Cl beams.

  20. Study of the production of neutron-rich isotope beams issuing from fissions induced by fast neutrons

    International Nuclear Information System (INIS)

    Lau, Ch.

    2000-01-01

    This work is a contribution to the PARRNe project (production of radioactive neutron-rich isotopes). This project is based on the fission fragments coming from the fission of 238-uranium induced by fast neutrons. The fast neutron flux is produced by the collisions of deutons in a converter. Thick targets of uranium carbide and liquid uranium targets have been designed in order to allow a quick release of fission fragments. A device, able to trap on a cryogenic thimble rare gas released by the target, has allowed the production of radioactive nuclei whose half-life is about 1 second. This installation has been settled to different deuton accelerators in the framework of the European collaboration SPIRAL-2. A calibration experiment has proved the feasibility of fixing an ISOL-type isotope separator to a 15 MV tandem accelerator, this installation can provide 500 nA deutons beams whose energy is 26 MeV and be a valuable tool for studying fast-neutron induced fission. Zinc, krypton, rubidium, cadmium, iodine, xenon and cesium beams have been produced in this installation. The most intense beams reach 10000 nuclei by micro-coulomb for 26 MeV deutons. An extra gain of 2 magnitude orders can be obtained by using a more specific ion source and by increasing the thickness of the target. Another extra gain of 2 magnitude orders involves 100 MeV deutons

  1. Microscopic study of neutron-rich dysprosium isotopes

    International Nuclear Information System (INIS)

    Vargas, Carlos E.; Velazquez, Victor; Lerma, Sergio

    2013-01-01

    Microscopic studies in heavy nuclei are very scarce due to large valence spaces involved. This computational problem can be avoided by means of the use of symmetry-based models. Ground-state, γ and β bands, and their B(E2) transition strengths in 160-168 Dy isotopes, are studied in the framework of the pseudo-SU(3) model which includes the preserving symmetry Q . Q term and the symmetry-breaking Nilsson and pairing terms, systematically parametrized. Additionally, three rotor-like terms are considered, whose free parameters, fixed for all members of the chain, are used to fine tune the moment of inertia of rotational bands and the band head of γ and β bands. The model succesfully describes in a systematic way rotational features in these nuclei and allows to extrapolate toward the midshell nucleus 170 Dy. The results presented show that it is possible to study a full chain of isotopes or isotones in the region with the present model. (orig.)

  2. Microscopic study of neutron-rich dysprosium isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Vargas, Carlos E. [Universidad Veracruzana, Facultad de Fisica e Inteligencia Artificial, Xalapa (Mexico); Universidad Nacional Autonoma de Mexico, Facultad de Ciencias, Apartado Postal 70-542, Mexico D.F. (Mexico); Velazquez, Victor [Universidad Nacional Autonoma de Mexico, Facultad de Ciencias, Apartado Postal 70-542, Mexico D.F. (Mexico); Lerma, Sergio [Universidad Veracruzana, Facultad de Fisica e Inteligencia Artificial, Xalapa (Mexico)

    2013-01-15

    Microscopic studies in heavy nuclei are very scarce due to large valence spaces involved. This computational problem can be avoided by means of the use of symmetry-based models. Ground-state, {gamma} and {beta} bands, and their B(E2) transition strengths in {sup 160-168}Dy isotopes, are studied in the framework of the pseudo-SU(3) model which includes the preserving symmetry Q . Q term and the symmetry-breaking Nilsson and pairing terms, systematically parametrized. Additionally, three rotor-like terms are considered, whose free parameters, fixed for all members of the chain, are used to fine tune the moment of inertia of rotational bands and the band head of {gamma} and {beta} bands. The model succesfully describes in a systematic way rotational features in these nuclei and allows to extrapolate toward the midshell nucleus {sup 170}Dy. The results presented show that it is possible to study a full chain of isotopes or isotones in the region with the present model. (orig.)

  3. Laser-spectroscopy studies of the nuclear structure of neutron-rich radium

    Science.gov (United States)

    Lynch, K. M.; Wilkins, S. G.; Billowes, J.; Binnersley, C. L.; Bissell, M. L.; Chrysalidis, K.; Cocolios, T. E.; Goodacre, T. Day; de Groote, R. P.; Farooq-Smith, G. J.; Fedorov, D. V.; Fedosseev, V. N.; Flanagan, K. T.; Franchoo, S.; Garcia Ruiz, R. F.; Gins, W.; Heinke, R.; Koszorús, Á.; Marsh, B. A.; Molkanov, P. L.; Naubereit, P.; Neyens, G.; Ricketts, C. M.; Rothe, S.; Seiffert, C.; Seliverstov, M. D.; Stroke, H. H.; Studer, D.; Vernon, A. R.; Wendt, K. D. A.; Yang, X. F.

    2018-02-01

    The neutron-rich radium isotopes, Ra-233222, were measured with Collinear Resonance Ionization Spectroscopy (CRIS) at the ISOLDE facility, CERN. The hyperfine structure of the 7 s2S10→7 s 7 p P31 transition was probed, allowing measurement of the magnetic moments, quadrupole moments, and changes in mean-square charge radii. These results are compared to existing literature values, and the new moments and change in mean-square charge radii of 231Ra are presented. Low-resolution laser spectroscopy of the very neutron-rich 233Ra has allowed the isotope shift and relative charge radius to be determined for the first time.

  4. Mass measurement and structure studies of neutron-rich isotopes of Zn, Ni, Fe

    International Nuclear Information System (INIS)

    Dessagne, P.

    1982-01-01

    With the Orsay MP Tandem, the reaction ( 14 C, 16 O) on 58 - 60 - 62 - 64 Ni, 64 - 66 - 68 - 70 Zn, 74 - 76 Ge and 82 Se targets, and the reaction ( 14 C, 15 O) on 60 - 62 - 64 Ni, 68 - 70 Zn, 76 Ge targets, have been investigated at 72 MeV bombarding energy. The mass excess of neutron rich nuclei: 63 Fe (-55.19+-.06MeV), 69 Ni(-60.14+-.06 MeV), 75 Zn(.62.7+-08 MeV) have been measured for the first time, and those of 62 Fe, 68 Ni, 74 Zn, 80 Ge have been remeasured. A new equipment has been designed in order to perform measurements at zero degree. From the angular distribution around 0 0 for the 70 Zn( 14 C, 16 O) reaction, the first state of 68 Ni observed for the first time (1.77 MeV +- .04 MeV) has been shown to be a 0 + . This result establishes a new case of 2 1+ - 0 2+ inversion. The systematics of the ( 14 C, 16 O) measurements on the even Ni and Zn isotopes have shown a different behaviour with two series. For the Ni → Fe (g.s.) transitions, the ratio σsub(exp)/σsub(DWBA) increases by a factor of four when the neutron number varies from 30 to 36. Whereas for the Zn → Ni (gs) transitions this ratio remains constant for the first three isotopes and decrease by a factor of two when N=40. For the Ni → Fe transitions, axial and spherical symmetries have been used. In agreement with the shell model no change are found with the spherical symmetry. For the axial symmetry a variation is observed but strongly dapendant of the sub-shell. Hence no clear conclusion can be deduced for the cross section estimate. For the Zn → Ni transitions, the spherical symmetry has been used. One configuration prevails, leading to a qualitative agreement with the experimental results [fr

  5. ${\\beta}$-decay studies of neutron-rich $^{61-70}$Mn isotopes with the new LISOL ${\\beta}$-decay setup

    CERN Document Server

    Diriken, J V J

    2008-01-01

    The aim of this proposal is to gather new information that will serve as benchmark to test shell model calculations in the region below $^{68}$Ni, where proper residual interactions are still under development. More specifically, the ${\\beta}$-decay experiment of the $^{61-70}$Mn isotopes will highlight the development of collectivity in the Fe isotopes and its daughters. At ISOLDE, neutron-rich Mn isotopes are produced with a UC$_{x}$ target and selective laser ionization. These beams are particularly pure and reasonable yields are obtained for the neutron-rich short lived $^{61-70}$Mn isotopes. We propose to perform ${\\beta}$-decay studies on $^{61-70}$Mn utilizing the newly-developed "LISOL ${\\beta}$-decay setup", consisting of two MINIBALL cluster Ge detectors and a standard tape station. The use of digital electronics in the readout of these detectors enables us to perform a "slow correlation technique" which should indicate the possible existence of isomers in the daughter nuclei.

  6. MR-ToF isobar separation for mass and life-time measurements of neutron-rich zinc at ISOLTRAP

    Energy Technology Data Exchange (ETDEWEB)

    Audi, Georges; Lunney, David; Wang, Meng [CSNSMIN2P3-CNRS, Universite de Paris Sud, Orsay (France); Beck, Dietrich; Herfurth, Frank; Kluge, Juergen; Ramirez, Enrique Minaya; Neidherr, Dennis [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); Blaum, Klaus; Boehm, Christine; Borgmann, Christopher; Cakirli, R. Burcu; Eliseev, Sergey [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Breitenfeldt, Martin [Leuven Univ. (Belgium). Inst. voor Kern- en Stralingsfysika; Cocolios, Thomas Elias; Kowalska, Magdalena [CERN, Geneva (Switzerland); George, Sebastian; Schwarz, Stefan [NSCL, Michigan State University, East Lansing, MI (United States); Herlert, Alexander [FAIR GmbH, Darmstadt (Germany); Kreim, Susanne [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); CERN, Geneva (Switzerland); Naimi, Sarah [RIKEN Research Facility (Japan); Rosenbusch, Marco; Schweikhard, Lutz; Wienholtz, Frank; Wolf, Robert N. [Ernst-Moritz-Arndt-Universitaet, Greifswald (Germany); Stanja, Juliane; Zuber, Kai [Technische Universitaet, Dresden (Germany)

    2012-07-01

    High-precision Penning-trap mass measurements of short-lived nuclei are performed with ISOLTRAP at the on-line isotope separator ISOLDE/CERN. An important prerequisite to achieve relative uncertainties of {delta}m/m=10{sup -8} is the availability of purely isobaric ion ensembles. To enhance the purity of radioactive ion beams, a multi-reflection time-of-flight mass separator developed at the University of Greifswald has recently been implemented at the ISOLTRAP setup. A mass resolving power of R=2.10{sup 5} and a contaminant reduction of four orders of magnitude by use of a Bradbury-Nielsen ion gate have been achieved. The performance of the combined setup (including an RFQ ion buncher, the MR-ToF MS and the two Penning traps) in both offline tests as well as in first applications with radioactive ion beams is presented. Furthermore, the physics case and recent results of mass measurements of neutron-rich Zinc are shown.

  7. Prompt Gamma-Ray Spectroscopy of Neutron-Rich Nuclides Produced in the Spontaneous Fission Process of CALIFORNIUM-252

    Science.gov (United States)

    Butler-Moore, S. Kyle

    Nuclear spectroscopy was performed on neutron -rich nuclides produced by the spontaneous fission process of ^{252}Cf. The data were taken with the Compton-suppressed Ge-detector spectrometer at the Holifield Heavy Ion Research Facility. The prompt gamma-ray transitions were isolated by using gamma-gamma and gamma-gamma -gamma coincidence techniques. Nine new states were observed in ^ {110}Ru, four of which constitute a gamma band structure up to J^pi = 7^+, and an additional J ^pi = 12^+ state which was assigned to the yrast band. The level scheme of ^{110}Ru is compared to ^{104}Ru and ^{192}Os, the latter of which shares with ^{110}Ru the distinction of having the lowest gamma-bandhead. Calculations with both the gamma-rigid triaxial nuclear model and the IBA O(6) Hamiltonian gave acceptable fits for the yrast band, but predicted a doublet clustering of states for the gamma-band, which was not observed experimentally. Studies of nuclei around doubly magic ^{132}Sn revealed for the first time energy levels of ^{136}Te and new high spin states in ^{134} Te, ^{138,140}Xe, and ^{140}Ba. The states in the yrast band of the N = 84 isotones ^ {136}Te, ^{138} Xe, and ^{140}Ba were determined up to 12^+, 12 ^+ and 8^+, respectively. The discovery of the 6^+ states provided an almost complete energy level systematics for the N = 84 isotones in the pseudo-spin f_{7/2 } shell. The energy levels of the isotopes ^{136}Te and ^{138}Xe were shown to exhibit remarkable similarities to the isotopes ^ {204}Po and ^{206 }Rn. This approximate symmetry was ascribed to the underlying shell model structure. Based upon the shell model calculations for ^{204 }Po, the 8^+, 10 ^+, and 12^+ states of ^{136}Te were hypothesized to involve core excitations of ^{134 }Sn. The higher spin states of the neutron-rich Pd isotopes ^{110,112,114}Pd were identified. Their moments of inertia exhibit backbending above spin 6^+. Cranked shell model calculations indicated that the backbendings observed at

  8. Goodness of isospin in neutron rich systems from the fission fragment distribution

    Science.gov (United States)

    Garg, Swati; Jain, Ashok Kumar

    2017-09-01

    We present the results of our calculations for the relative yields of neutron-rich fission fragments emitted in 208Pb (18O, fission) reaction by using the concept of the conservation of isospin and compare with the experimental data. We take into account a range of isospin values allowed by the isospin algebra and assume that the fission fragments are formed in isobaric analog states. We also take into account the neutron multiplicity data for various neutron-emission channels in each partition, and use them to obtain the weight factors in calculating the yields. We then calculate the relative yields of the fission fragments. Our calculated results are able to reproduce the experimental trends reasonably well. This is the first direct evidence of the isospin conservation in neutron-rich systems and may prove a very useful tool in their studies.

  9. Nuclear structure far from stability: the neutron-rich 69-79Cu isotopes

    International Nuclear Information System (INIS)

    Franchoo, Serge

    2015-01-01

    Far from stability, the nuclear structure that is predicted by the shell model is evolving. Old magic numbers disappear, while new ones appear. Our understanding of the underlying nuclear force that drives these changes is still incomplete. After a short overview across the nuclear chart, we discuss the strength functions of the shell-model orbitals in the neutron-rich copper isotopes towards the 78 Ni doubly-magic nucleus. These were measured in a 72 Zn(d, 3 He) 71 Cu proton pick-up reaction in inverse kinematics with a radioactive beam at the Ganil laboratory in France. We also present the latest results from a 80 Zn(p,2p) 79 Cu knockout experiment at Riken in Japan, leading to selective population of hole states in 79 Cu. Our findings show that the Z=28 shell gap in the neutron-rich copper isotopes is surprisingly steady against the addition of neutrons beyond N=40. (author)

  10. Experimental determination of one- and two-neutron separation energies for neutron-rich copper isotopes

    Science.gov (United States)

    Yu, Mian; Wei, Hui-Ling; Song, Yi-Dan; Ma, Chun-Wang

    2017-09-01

    A method is proposed to determine the one-neutron S n or two-neutron S 2n separation energy of neutron-rich isotopes. Relationships between S n (S 2n) and isotopic cross sections have been deduced from an empirical formula, i.e., the cross section of an isotope exponentially depends on the average binding energy per nucleon B/A. The proposed relationships have been verified using the neutron-rich copper isotopes measured in the 64A MeV 86Kr + 9Be reaction. S n, S 2n, and B/A for the very neutron-rich 77,78,79Cu isotopes are determined from the proposed correlations. It is also proposed that the correlations between S n, S 2n and isotopic cross sections can be used to find the location of neutron drip line isotopes. Supported by Program for Science and Technology Innovation Talents at Universities of Henan Province (13HASTIT046), Natural and Science Foundation in Henan Province (162300410179), Program for the Excellent Youth at Henan Normal University (154100510007) and Y-D Song thanks the support from the Creative Experimental Project of National Undergraduate Students (CEPNU 201510476017)

  11. 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

  12. Investigation of exotic modes of spinning nuclei near Zr

    Indian Academy of Sciences (India)

    2014-04-01

    Apr 1, 2014 ... Recently, a digital data acquisition system with 96 channels has been set up for the. Indian National ... vibration with other modes, high spin states of neutron-rich nuclei in sd-shell and isomers near-shell .... and integrated polarization direction correlation (IPDCO) analysis of different transitions were carried ...

  13. Production and identification of very exotic nuclei

    International Nuclear Information System (INIS)

    Pougheon, F.

    1986-01-01

    New very exotic nuclei have been produced by fragmentation of the projectile at intermediate energy at GANIL. They have been identified through time of flight and ΔE-E measurements after a magnetic separation with the 0 0 LISE spectrometer. New neutron rich isotopes have been identified up to Z = 26 and evidence for the stability of the new series Tz = -5/2 has been shown. These results improve the knowledge of the neutron and proton drip lines

  14. Self-consistent quasiparticle formulation of a multiphonon method and its application to the neutron-rich O20 nucleus

    Science.gov (United States)

    De Gregorio, G.; Knapp, F.; Lo Iudice, N.; Vesely, P.

    2016-04-01

    A Bogoliubov quasiparticle formulation of an equation-of-motion phonon method, suited for open-shell nuclei, is derived. Like its particle-hole version, it consists of deriving a set of equations of motions whose iterative solution generates an orthonormal basis of n -phonon states (n =0 ,1 ,2 ,... ), built of quasiparticle Tamm-Dancoff phonons, which simplifies the solution of the eigenvalue problem. The method is applied to the open-shell neutron-rich O20 for illustrative purposes. A Hartree-Fock-Bogoliubov canonical basis, derived from an intrinsic two-body optimized chiral Hamiltonian, is used to derive and solve the eigenvalue equations in a space encompassing a truncated two-phonon basis. The spurious admixtures induced by the violation of the particle number and the center-of-mass motion are eliminated to a large extent by a Gram-Schmidt orthogonalization procedure. The calculation takes into account the Pauli principle, is self-consistent, and is parameter free except for the energy cutoff used to truncate the two-phonon basis, which induces an increasing depression of the ground state through its strong coupling to the quasiparticle vacuum. Such a cutoff is fixed so as to reproduce the first 1- level. The two-phonon states are shown to enhance the level density of the low-energy spectrum, consistently with the data, and to induce a fragmentation of the E 1 strength which, while accounting for the very low E 1 transitions, is not sufficient to reproduce the experimental cross section in the intermediate energy region. This and other discrepancies suggest the need of including the three-phonon states. These are also expected to offset the action of the two phonons on the quasiparticle vacuum and, therefore, free the calculation from any parameter.

  15. Measurement of light charged particles in the decay channels of medium-mass excited compound nuclei

    International Nuclear Information System (INIS)

    Valdre, S.; Pasquali, G.; Carboni, S.; Bini, M.; Poggi, G.; Barlini, S.; Casini, G.; Piantelli, S.; Bardelli, L.; Nannini, A.; Cinausero, M.; Gramegna, F.; Degerlier, M.; Kravchuk, V.L.; Marchi, T.; Baiocco, G.; Bruno, M.; D'Agostino, M.; Morelli, L.; Vannini, G.; Benzoni, G.; Blasi, N.; Brambilla, S.; Wieland, O.; Bracco, A.; Camera, F.; Corsi, A.; Crespi, F.; Leoni, S.; Million, B.; Nicolini, R.; Montanari, D.; Bednarczyk, P.; Ciemala, M.; Fornal, B.; Kmiecik, M.; Maj, A.; Matejska-Minda, M.; Mazurek, K.; Meczynski, W.; Myalski, S.; Styczen, J.; Zieblinski, M.; Dudek, J.

    2014-01-01

    The 48 Ti on 40 Ca reactions have been studied at 300 and 600 MeV focusing on the fusion-evaporation (FE) and fusion-fission (FF) exit channels. Energy spectra and multiplicities of the emitted light charged particles have been compared to Monte Carlo simulations based on the statistical model. Proton emission in the FE channel is well reproduced by the Gemini++ statistical code run with standard input values. An excess of particles has been found at both bombarding energies also associated to a slightly different CM-energy spectrum with respect to the predicted one. Indeed, in this mass region (A ∼ 100) models predict that shape transitions can occur at high spin values and relatively scarce data exist in the literature about coincidence measurements between evaporation residues and light charged particles. Signals of shape transitions can be found in the variations of the lineshape of high energy gamma rays emitted from the de-excitation of GDR states gated on different regions of angular momenta. For this purpose it is important to keep under control the FE and FF processes, to regulate the statistical model parameters and to control the onset of possible preequilibrium emissions from 300 to 600 MeV bombarding energy

  16. Investigation of the core-halo structure of the neutron-rich nuclei {sup 6}He and {sup 8}He by intermediate-energy elastic proton scattering at high momentum transfer; Etude de la structure coeur-halo des noyaux riches en neutron {sup 6}He et {sup 8}He par la diffusion elastique de protons aux energies intermediaires etendue a la region du premier minimum de diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Aksouh, F

    2002-12-01

    The elastic proton scattering from the halo nuclei {sup 6}He and {sup 8}He was investigated in inverse kinematics at energies around 700 MeV/u with the aim to deduce the differential cross sections for the region of high momentum transfer, covering the first diffraction minimum. For this purpose, a liquid-hydrogen target was specially developed and used for the first time allowing to obtain low-background data as compared to commonly used targets made from C-H compounds. Previous data taken in the region of small momentum transfer were sensitive to the size and the peripheral shape of the total nuclear matter density distribution but not to the inner part. The present data allow for a more detailed insight in the structure of the alike core in {sup 6,8}He through a better determination of the matter density distributions. Several density distributions calculated from different microscopic models were used to derive elastic scattering cross sections which are compared with the obtained data. (author)

  17. Coulomb excitation of neutron-rich $^{134-136}$Sn isotopes

    CERN Multimedia

    We propose to study excited states in the isotopes $^{134,136}$Sn by $\\gamma$-ray spectroscopy following "safe" Coulomb excitation. The experiment aims to investigate the evolution of quadrupole collectivity beyond the magic shell closure at N = 82 by the determination of B(E2) values and electric quadrupole moments $\\mathcal{Q}_2$. Recent shell-model calculations using realistic interactions predict possible enhanced collectivity in neutron-rich regions. Evidence for this could be obtained by this experiment. Furthermore, the currently unknown excitation energies of the 2$^+_{1}$ and 4$^+_{1}$ states in $^{136}$Sn will be measured for the first time.

  18. Application of the generator coordinate method to neutron-rich Se and Ge isotopes

    Directory of Open Access Journals (Sweden)

    Higashiyama Koji

    2014-03-01

    Full Text Available The quantum-number projected generator coordinate method (GCM is applied to the neutron-rich Se and Ge isotopes, where the monopole and quadrupole pairing plus quadrupole-quadrupole interaction is employed as an effective interaction. The energy spectra obtained by the GCM are compared to both the shell model results and the experimental data. The GCM reproduces well the energy levels of high-spin states as well as the low-lying states. The structure of the low-lying collective states is analyzed through the GCM wave functions.

  19. Evolution of deformation in neutron-rich Ba isotopes up to A=150

    DEFF Research Database (Denmark)

    Lica, R.; Benzoni, G.; Rodriguez, T. R.

    2018-01-01

    The occurrence of octupolar shapes in the Ba isotopic chain was recently established experimentally up to N = 90. To further extend the systematics, the evolution of shapes in the most neutron-rich members of the Z = 56 isotopic chain accessible at present, Ba-148,Ba-150, has been studied via bet....... The experimental data are compared to symmetry conserving configuration mixing (SCCM) calculations, confirming an evolution of increasingly quadrupole deformed shapes with a definite octupolar character.......The occurrence of octupolar shapes in the Ba isotopic chain was recently established experimentally up to N = 90. To further extend the systematics, the evolution of shapes in the most neutron-rich members of the Z = 56 isotopic chain accessible at present, Ba-148,Ba-150, has been studied via beta...... determined, resulting in T-1/2 = 1.51(1) ns for Ba-148 and T-1/2 = 3.4(2) ns for Ba-150. The systematics of low-spin states, together with the experimental determination of the B(E2 : 2(+) -> 0(+)) transition probabilities, indicate an increasing collectivity in Ba148-150, towards prolate deformed shapes...

  20. Probing the density tail of radioactive nuclei with antiprotons

    CERN Document Server

    Obertelli, Alexandre; Uesaka, Tomohiro; Corsi, Anna; Pollacco, Emmanuel; Flavigny, Freddy

    2017-01-01

    We propose an experiment to determine the proton and neutron content of the radial density tail in short-lived nuclei. The objectives are to (i) to evidence new proton and neutron halos, (ii) to understand the development of neutron skins in medium-mass nuclei, (iii) to provide a new observable that characterises the density tail of short-lived nuclei.

  1. Nuclei in a neutron star

    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)

  2. Identification and Decay Studies of New, Neutron-Rich Isotopes of Bismuth, Lead and Thallium by means of a Pulsed Release Element Selective Method

    CERN Multimedia

    Mills, A; Kugler, E; Van duppen, P L E; Lettry, J

    2002-01-01

    % IS354 \\\\ \\\\ It is proposed to produce, identify and investigate at ISOLDE new, neutron-rich isotopes of bismuth, lead and thallium at the mass numbers A=215 to A=218. A recently tested operation mode of the PS Booster-ISOLDE complex, taking an advantage of the unique pulsed proton beam structure, will be used together with a ThC target in order to increase the selectivity. The decay properties of new nuclides will be studied by means of $\\beta$-, $\\gamma$- and X- ray spectroscopy methods. The expected information on the $\\beta$-half-lives and excited states will be used for testing and developing the nuclear structure models ``south-east'' of $^{208}$Pb, and will provide input data for the description of the r-process path at very heavy nuclei. The proposed study of the yields and the decay properties of those heavy nuclei produced in the spallation of $^{232}$Th by a 1~GeV proton beam contributes also the data necessary for the simulations of a hybrid accelerator-reactor system.

  3. Octupole correlations in neutron-rich {sup 143,145}Ba and a type of superdeformed band in {sup 145}Ba

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, S.J.; Wang, M.G.; Long, G.L.; Zhu, L.Y.; Gan, C.Y.; Yang, L.M.; Sakhaee, M.; Li, M.; Deng, J.K. [Physics Department, Tsinghua University, Beijing 100084, Peoples Republic of (China); Zhu, S.J.; Hamilton, J.H.; Ramayya, A.V.; Jones, E.F.; Hwang, J.K.; Zhang, X.Q.; Gore, P.M.; Peker, L.K.; Drafta, G.; Babu, B.R.; Deng, J.K.; Ginter, T.N.; Beyer, C.J.; Kormicki, J.; Ter-Akopian, G.M.; Daniel, A.V. [Physics Department, Vanderbilt University, Nashville, Tennessee 37235 (United States); Zhu, S.J.; Ter-Akopian, G.M.; Daniel, A.V. [Joint Institute for Heavy Ion Research, Oak Ridge, Tennessee 37831 (United States); Ma, W.C. [Physics Department, Mississippi State University, Mississippi 39762 (United States); Cole, J.D.; Aryaeinejad, R.; Drigert, M.W. [Idaho National Engineering Laboratory, Idaho Falls, Idaho 83415 (United States); Rasmussen, J.O.; Asztalos, S.; Lee, I.Y.; Macchiavelli, A.O.; Chu, S.Y.; Gregorich, K.E.; Mohar, M.F. [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Ter-Akopian, G.M.; Daniel, A.V.; Oganessian, Y.T.; Kliman, J. [Flerov Laboratory for Nuclear Reactions, Joint Institute for Nuclear Research, Dubna (Russia); Donangelo, R. [Universidade Federal do Rio de Janeiro, Caixa Postal 68528, RG (Brazil); Stoyer, M.A.; Lougheed, R.W.; Moody, K.J.; Wild, J.F. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Prussin, S.G. [Nuclear Engineering Department, University of California at Berkeley, Berkeley, California 94720 (United States); Kliman, J. [Institute of Physics, SASc, Dubravskacesta 9, 84228 Bratislava (Slovakia); Griffin, H.C. [University of Michigan, Ann Arbor, Michigan 48104 (United States)

    1999-11-01

    High spin states in neutron-rich odd-{ital Z} {sup 143,145}Ba nuclei have been investigated from the study of prompt {gamma} rays in the spontaneous fission of {sup 252}Cf by using {gamma}-{gamma}- and {gamma}-{gamma}-{gamma}- coincidence techniques. Alternating parity bands are identified for the first time in {sup 145}Ba and extended in {sup 143}Ba. A new side band, with equal, constant dynamic, and kinetic moments of inertia equal to the rigid body value, as found in superdeformed bands, is discovered in {sup 145}Ba. Enhanced E1 transitions between the negative- and positive-parity bands in these nuclei give evidence for strong octupole deformation in {sup 143}Ba and in {sup 145}Ba. These collective bands show competition and coexistence between symmetric and asymmetric shapes in {sup 145}Ba. Evidence is found for crossing M1 and E1 transitions between the s=+i and s={minus}i doublets in {sup 143}Ba. {copyright} {ital 1999} {ital The American Physical Society}

  4. 3rd International conference on nuclei far from stability, Cargese, Corsica, 19-26 May 1976

    International Nuclear Information System (INIS)

    1976-01-01

    These conference proceedings contain 103 contributions which are grouped under the following headings: Experimental methods and techniques; Perspectives in research on exotic nuclei; Nuclear masses - experiment and theory; Nuclear spins, moments, and radii; Light nuclei; Delayed particle emission and statistical aspects; Excited states of neutron-deficient nuclei; Excited states of fission products and other neutron-rich isotopes; Heavy elements and astrophysical aspects. Also included are the Scientific programme and a List of participants. (AJ)

  5. Investigation of the single Particle Structure of the neutron-rich Sodium Isotopes $^{27-31}\\!$Na

    CERN Multimedia

    2002-01-01

    We propose to study the single particle structure of the neutron-rich isotopes $^{27-31}\\!$Na. These isotopes will be investigated via neutron pickup reactions in inverse kinematics on a deuterium and a beryllium target. Scattered beam particles and transfer products are detected in a position sensitive detector located around 0$^\\circ$. De-excitation $\\gamma$-rays emitted after an excited state has been populated will be registered by the MINIBALL Germanium array. The results will shed new light on the structure of the neutron-rich sodium isotopes and especially on the region of strong deformation around the N=20 nucleus $^{31}\\!$Na.

  6. Structure of the neutron rich Ga and Ge isotopes observed at ALTO

    International Nuclear Information System (INIS)

    Verney, D.; Lebois, M.; Ibrahim, F.

    2009-01-01

    During test runs dedicated to the commissioning of ALTO (Accelerateur Lineaire et Tandem a Orsay), β and β-n decay of the very neutron rich 31 84 Ga 53 could be observed at the tape station installed on-line with the PARRNe mass-separator. γ-lines observed in the resulting spectra and a careful analysis of the balance of their relative intensities point toward the existence of two β-decaying states in 84 Ga. The decay of these long-lived states appear to feed the 2 1 + and 4 1 + excited states of 32 84 Ge 52 and the 1/2 1 + state in 32 83 Ge 51 allowing a significant improvement of the knowledge on nuclear structure in the immediate vicinity of 78 Ni. (author)

  7. Mass measurements of neutron-rich indium isotopes toward the N =82 shell closure

    Science.gov (United States)

    Babcock, C.; Klawitter, R.; Leistenschneider, E.; Lascar, D.; Barquest, B. R.; Finlay, A.; Foster, M.; Gallant, A. T.; Hunt, P.; Kootte, B.; Lan, Y.; Paul, S. F.; Phan, M. L.; Reiter, M. P.; Schultz, B.; Short, D.; Andreoiu, C.; Brodeur, M.; Dillmann, I.; Gwinner, G.; Kwiatkowski, A. A.; Leach, K. G.; Dilling, J.

    2018-02-01

    Precise mass measurements of the neutron-rich In-130125 isotopes have been performed with the TITAN Penning trap mass spectrometer. TITAN's electron beam ion trap was used to charge breed the ions to charge state q =13 + thus providing the necessary resolving power to measure not only the ground states but also isomeric states at each mass number. In this paper, the properties of the ground states are investigated through a series of mass differentials, highlighting trends in the indium isotopic chain as compared to its proton-magic neighbor, tin (Z =50 ). In addition, the energies of the indium isomers are presented. The (8-) level in 128In is found to be 78 keV lower than previously thought and the (21 /2- ) isomer in 127In is shown to be lower than the literature value by more than 150 keV.

  8. Observation of rotational bands in neutron-rich sup 1 sup 0 sup 6 Mo nucleus

    CERN Document Server

    Xu Rui Qing; Li Ke; Yang Li Ming; Zhu Ling Yan; Gan Cui Yun; Zhang Zheng; Jiang Zhuo; Xiao Shu Dong; Hamilton, J H; Ramayya, A V; Hwang, J K; Zhang, X Q; Kormicki, J; Jones, E F; Ma, W C; Cole, J D; Aryaeinejad, R; Drigert, M W; Lee, I Y; Rasmussen, J O; Stoyer, M A; Ter-Akopian, G M; Daniel, A V

    2002-01-01

    The rotational bands up to a spin of 16 Planck constant in the neutron-rich sup 1 sup 0 sup 6 Mo nucleus have been investigated by measuring high-fold prompt gamma-ray coincidence events following spontaneous fission of sup 2 sup 5 sup 2 Cf with a Gamma-sphere detector array. The ground-state band, the one-phonon and two-phonon gamma-vibrational bands, as well as a quasi-particle band have been confirmed and expanded. The other four collective rotational bands, three proposed as two quasi-particle bands and one proposed as a beta-vibrational band, have been newly observed. The characteristics of these collective bands and the possible configurations for the quasi-particle bands are discussed

  9. Intermediate-mass single stars and accreting white dwarfs as sources of neutron-rich isotopes

    International Nuclear Information System (INIS)

    Iben, I. Jr.

    1981-01-01

    During the most luminous portion of the asymptotic giant-branch phase, models of intermediate-mass stars first become carbon stars and then produce s-process isotopes in the solar-system distribution. Recent observations of the optically most luminous carbon stars in the Magellanic Clouds introduce the possibility that real intermediate-mass stars lose their hydrogen-rich envelopes during the asymptotic giant-branch phase before they have made s-process isotopes both in large quantities and in the solar system distribution. This encourages a search for alternate sources of these isotopes. A promising site for the production of some neutron-rich isotopes isthe convective helium-carbon region that appears in accreting white dwarfs during helium shell flashes. For appropriate accretion rates, overlap of matter in successive convective zones may lead to an exponential distribution of exposures. Further, because of a small entropy barrier between the convective shell and the hydrogen-rich envelope, protons enter the shell and provide a source of neutrons that, for appropriate accretion rates, is repetitive in strength and either dominates or is complementary to the 22 Ne(α,n) 25 Mg source. This permits an estimate of the distribution of neutron-rich isotopes that is formed after many flashes. The distribution, in most instances, tends to be weighted more toward heavier elements than is the case when 22 Ne(α, n) 25 Mg is the sole source of neutrons. Hence, accreting white dwarfs cannot be major contributors to the enrichment of the interstellar medium in most s-process isotopes. Considerable effort should be devoted toward demonstrating whether or not the bolometrically most lumious asymptotic giant branch stars in local systems obey M/sub BOL/ /sup min/ -6.5, then either the source of most Galactic s-process isotopes is as yet unknown, or the rate of the 22 Ne(α, n) 25 Mg reaction has been underestimated

  10. Spectroscopy of neutron-rich nuclei populated in the spontaneous fission of 252Cf and 248Cm

    International Nuclear Information System (INIS)

    Smith, A. G.; Simpson, G. S.; Billowes, J.; Durell, J. L.; Phillips, W. R.; Dagnall, P. J.; Freeman, S. J.; Leddy, M.; Roach, A. A.; Smith, J. F.

    1999-01-01

    In this paper we present research that has been carried out using the Euroball and Eurogam arrays to detect γ rays emitted from spontaneously fissioning 248 Cm and 252 Cf. The paper focuses on three sub-areas of current activity, namely, the measurement of yields of secondary fragment pairs, the measurement of state lifetimes at around spin 10, and recent measurements of g-factors of excited states in fission fragments. (c) 1999 American Institute of Physics

  11. Commissioning of the BRIKEN beta-delayed neutron detector for the study of exotic neutron-rich nuclei

    Directory of Open Access Journals (Sweden)

    Tolosa-Delgado A.

    2017-01-01

    Full Text Available The commissioning of a new setup for β-delayed neutron measurements was carried out successfully in November-2016, at the RIKEN Nishina Center in Japan. The β-decay half-lives and Pn branching ratios of several isotopes in the 78Ni region were measured. Details of the experimental setup and the first results are given.

  12. Studies of Neutron-Rich Nuclei with (d,p) Reactions in Inverse Kinematics at the HRIBF

    International Nuclear Information System (INIS)

    Grzywacz-Jones, Kate L.; Baktash, Cyrus; Bardayan, Daniel W.; Blackmon, Jeff C.; Catford, Wilton N.; Cizewski, Jolie; Fitzgerald, Ryan; Greife, Uwe; Gross, Carl J.; Johnson, Micah; Kozub, Raymond L.; Liang, J. Felix; Livesay, Jake; Ma, Zhanwen; Moazen, Brian H.; Nesaraja, Caroline D.; Shapira, Dan; Smith, Michael Scott; Thomas, Jeffrey S.; Visser, Dale William

    2005-01-01

    Two N=51 isotones have been measured using (d,p) reactions in inverse kinematics at the Holifield Radioactive Beam Facility (HRIBF) of Oak Ridge National Laboratory. Additionally, we have performed a test measurement using a stable 124Sn beam in preparation for measurements of the 2H(130,132Sn,p)131,133Sn reactions. Preliminary results for 83Ge and 85Se suggest a 5/2+ ground state and a 1/2+ first excited state for both isotopes, in agreement with systematics for the N=51 isotones. The excitation energy of the first excited state is shown to drop as the proton number is reduced. Proton angular distributions following the 2H(124Sn,p)125Sn reaction show sensitivity to the l-value of the transfered nucleon and spectroscopic factors are in agreement with previous measurements in normal kinematics.

  13. Deep inelastic reactions and isomers in neutron-rich nuclei across the perimeter of the A = 180 - 190 deformed region

    International Nuclear Information System (INIS)

    Dracoulis, G.D.; Lane, G.J.; Byrne, A.P.; Watanabe, H.; Hughes, R.O.; Kondev, F.G.; Carpenter, M.P.; Janssens, R.V.F.; Lauritsen, T.; Lister, C.J.; Seweryniak, D.; Zhu, S.; Chowdhury, P.; Shi, Y.; Xu, F.R.

    2014-01-01

    Recent results on high-spin isomers populated in deep-inelastic reactions in the transitional tungsten-osmium region are outlined with a focus on 190 Os, 192 Os and 194 Os. As well as the characterization of several two-quasineutron isomers, the 12 + and 20 + isomers in 192 Os are interpreted as manifestations of maximal rotation alignment within the neutron i(13/2) and possibly proton h(11/2) shells at oblate deformation. (authors)

  14. Beta decay rates for nuclei with 115

    Indian Academy of Sciences (India)

    ∗E-mail: chakra@csupomona.edu. MS received 13 November 2005; revised 11 January 2006; accepted 15 March 2006. Abstract. For r-process nucleosynthesis the β-decay rates for a number of neutron-rich intermediate heavy nuclei are calculated. The model for the β-strength function is able to reproduce the observed ...

  15. Fusion of light exotic nuclei at near-barrier energies: Effect of ...

    Indian Academy of Sciences (India)

    The effect of inelastic excitation of exotic light projectiles (proton- as well as neutron- rich) 17F and 11Be ... coupling of the ground state of the projectile to the continuum, inelastic excitation of the projectile to the bound ... P Banerjee et al that any coupling of the relative motion of the colliding nuclei to nuclear intrinsic excita-.

  16. Ultra-fast timing study of exotic neutron-rich Fe isotopes

    CERN Document Server

    Olaizola, Bruno; Mach, Henryk

    The cornerstone of nuclear structure, as we know it from stable nuclei, is the existence of magic numbers. The most stable nuclei arise for completely occupied shells, closed shells, and give rise to the magic numbers. At the Valley of Stability their values are 8, 20, 28, 50, 82 and 126. The steady development of the production, separation and identication of exotic nuclei, together with the improvement of the detection techniques, makes it possible to experimentally explore nuclei further away from the Valley of Stability. These exotic nuclei with nucleon numbers supposed to be magic do not always have the properties one would expect. As extra nucleons are added (or removed) from stable nuclei, the single particle energies are modied and strong quadrupole correlations appear, which may neutralize the spherical meanfield shell gaps. The investigation of the evolution of shell structure far from stability has become a major subject in Nuclear Physics. Research in this field has strong implications also in nuc...

  17. Neutron-rich Λ-Hypernuclei study with the FINUDA experiment

    Directory of Open Access Journals (Sweden)

    Botta E.

    2014-03-01

    Full Text Available The FINUDA experiment at DAΦNE, Frascati, has found evidence for the neutron-rich hypernucleus HΛ6${}_ \\wedge ^6{\\rm{H}}$ studying (π+, π− pairs in coincidence from the Kstop−+L6i→HΛ6+π+$K_{{\\rm{stop}}}^ - + {}^{\\rm{6}}{\\rm{Li}} \\to {}_ \\wedge ^6{\\rm{H}} + {\\pi ^ + }$ production reaction followed by HΛ6→H6e +π−${}_ \\wedge ^6{\\rm{H}} \\to {}^6{\\rm{He + }}{\\pi ^ - }$ weak decay. The production rate of HΛ6${}_ \\wedge ^6{\\rm{H}}$ undergoing this two-body π− decay has been found to be (2.9±2.0⋅10−6/Kstop−$(2.9 \\pm 2.0 \\cdot {10^{ - 6}}/K_{{\\rm{stop}}}^ - $. Its binding energy has been evaluated to be BΛ(HΛ6=(4.0±1.1${B_ \\wedge }({}_ \\wedge ^6H = (4.0 \\pm 1.1$ MeV with respect to (H5+Λ$({}^5{\\rm{H}} + \\Lambda $, jointly from production and decay. A systematic difference of (0.98 ± 0.74 MeV between BΛ values derived separately from decay and from production has been tentatively assigned to the HΛ6 0g.s.+→1+${}_\\Lambda ^6{\\rm{H 0}}_{{\\rm{g}}{\\rm{.s}}{\\rm{.}}}^ + \\to {1^ + }$ excitation. A similar investigation has been carried out for the neutron-rich hypernucleus HΛ9e${}_\\Lambda ^9{\\rm{He}}$ studying the Kstop−+B9e→HΛ9e+π+$K_{{\\rm{stop}}}^ - + {}_{}^{\\rm{9}}{\\rm{Be}} \\to {}_\\Lambda ^9{\\rm{He}} + {\\pi ^ + }$ reaction in coincidence with the H Λ 9e→ L 9i +  π −${}_\\Lambda ^9{\\rm{He}} \\to {}_{}^{\\rm{9}}{\\rm{Li + }}{\\pi ^ - }$ weak decay; an upper limit for the production rate of HΛ9e${}_\\Lambda ^9{\\rm{He}}$ undergoing the two-body π− decay has been found to be 4.2⋅10 −6 /K stop− $4.2 \\cdot {10^{ - 6}}/{\\rm{K}}_{stop}^ - $ (90% C.L..

  18. Neutron-Rich Silver Isotopes Produced by a Chemically Selective Laser Ion-Source: Test of the R-Process " Waiting-Point " Concept

    CERN Multimedia

    2002-01-01

    The r-process is an important nucleosynthesis mechanism for several reasons: \\begin{enumerate} \\item It is crucial to an understanding of about half of the A>60 elemental composition of the Galaxy; \\item It is the mechanism that forms the long-lived Th-U-Pu nuclear chronometers which are used for cosmochronolgy; \\item It provides an important probe for the temperature (T$ _{9} $)-neutron density ($n_{n}$) conditions in explosive events; and last but not least \\item It may serve to provide useful clues to and constraints upon the nuclear properties of very neutron-rich heavy nuclei. \\end{enumerate} \\\\ \\\\With regard to nuclear-physics data, of particular interest are the T$ _{1/2} $ and P$_{n-} $ values of certain$\\,$ "waiting-point"$\\,$ isotopes in the regions of the A $ \\approx $ 80 and 130. r-abundance peaks. Previous studies of $^{130}_{\\phantom{1}48}$Cd$_{82}$ and $^{79}_{29}$Cu$_{50}$. $\\beta$-decay properties at ISOLDE using a hot plasma ion source were strongly complicated by isobar and molecular-ion c...

  19. Search for low lying dipole strength in the neutron rich nucleus Ne{sup 26}

    Energy Technology Data Exchange (ETDEWEB)

    Gibelin, J

    2005-11-15

    We carried out the Coulomb excitation, on a lead target, of an exotic beam of neutron-rich nucleus Ne{sup 26} at 58 MeV/n, in order to study the possible existence of a pygmy dipole resonance above the neutron emission threshold. The experiment was performed at the Riken Research Facility, in Tokyo (Japan) and included a gamma-ray detector, a charged fragment hodoscope and a neutron detector. Using the invariant mass method in the Ne{sup 25} + n decay channel, and by comparing the reaction cross section on the lead target and a light target of aluminum, we observe a sizable amount of E1 strength between the one neutron and the two neutron emission thresholds. The corresponding Ne{sup 26} angular distribution confirms its nature and we deduce its reduced dipole transition probability value of B(E1) = 0.54 {+-} 0.18 e{sup 2}fm{sup 2}. Our method also enables us to extract for the first time the decay pattern of a pygmy resonance. By detecting the decay photons from the excited states below the neutron emission threshold and by analyzing the angular distribution of the inelastically scattered Ne{sup 26} we deduce the reduced transition probability of the first 2{sup +} state, from the ground state. The value obtained of B(E2) = 87 {+-} 13 e{sup 2}fm{sup 4} being in disagreement with a previous result. (author)

  20. Light neutron-rich hypernuclei from the importance-truncated no-core shell model

    Science.gov (United States)

    Wirth, Roland; Roth, Robert

    2018-04-01

    We explore the systematics of ground-state and excitation energies in singly-strange hypernuclei throughout the helium and lithium isotopic chains - from He5Λ to He11Λ and from Li7Λ to Li12Λ - in the ab initio no-core shell model with importance truncation. All calculations are based on two- and three-baryon interaction from chiral effective field theory and we employ a similarity renormalization group transformation consistently up to the three-baryon level to improve the model-space convergence. While the absolute energies of hypernuclear states show a systematic variation with the regulator cutoff of the hyperon-nucleon interaction, the resulting neutron separation energies are very stable and in good agreement with available data for both nucleonic parents and their daughter hypernuclei. We provide predictions for the neutron separation energies and the spectra of neutron-rich hypernuclei that have not yet been observed experimentally. Furthermore, we find that the neutron drip lines in the helium and lithium isotopic chains are not changed by the addition of a hyperon.

  1. Low-energy Coulomb excitation of neutron-rich zinc isotopes

    CERN Document Server

    Van de Walle, J; Behrens, T; Bildstein, V; Blazhev, A; Cederkäll, J; Clément, E; Cocolios, T E; Davinson, T; Delahaye, P; Eberth, J; Ekström, A; Fedorov, D V; Fedosseev, V; Fraile, L M; Franchoo, S; Gernhäuser, R; Georgiev, G; Habs, D; Heyde, K; Huber, G; Huyse, M; Ibrahim, F; Ivanov, O; Iwanicki, J; Jolie, J; Kester, O; Köster, U; Kröll, T; Krücken, R; Lauer, M; Lisetskiy, A F; Lutter, R; Marsh, B A; Mayet, P; Niedermaier, O; Pantea, M; Raabe, R; Reiter, P; Sawicka, M; Scheit, H; Schrieder, G; Schwalm, D; Seliverstov, M D; Sieber, T; Sletten, G; Smirnova, N; Stanoiu, M; Stefanescu, I; Thomas, J C; Valiente-Dobón, J J; Van Duppen, P; Verney, D; Voulot, D; Warr, N; Weisshaar, D; Wenander, F; Wolf, B H; Zielinska, M

    2009-01-01

    At the radioactive ion beam facility REX-ISOLDE, neutron-rich zinc isotopes were investigated using low-energy Coulomb excitation. These experiments have resulted in B(E2,20) values in 74-80Zn, B(E2,42) values in 74,76Zn and the determination of the energy of the first excited 2 states in 78,80Zn. The zinc isotopes were produced by high-energy proton- (A=74,76,80) and neutron- (A=78) induced fission of 238U, combined with selective laser ionization and mass separation. The isobaric beam was postaccelerated by the REX linear accelerator and Coulomb excitation was induced on a thin secondary target, which was surrounded by the MINIBALL germanium detector array. In this work, it is shown how the selective laser ionization can be used to deal with the considerable isobaric beam contamination and how a reliable normalization of the experiment can be achieved. The results for zinc isotopes and the N=50 isotones are compared to collective model predictions and state-of-the-art large-scale shell-model calculations, i...

  2. New measurements of the properties of neutron-rich projectile fragments

    Science.gov (United States)

    Morrissey, D. J.; Meierbachtol, K.; Mosby, M.; Thoennessen, M. R.; MoNa Collaboration

    2013-03-01

    Two new experiments were carried out at the NSCL to explore the details of the linear moment and excitation energy distributions of projectile fragmentation production. In the first experiment the full linear momentum distributions of fragments from the reaction of a 76 Ge beam with beryllium and gold targets were measured in the S800 spectrometer. The results indicate a strong contribution of "far side" or attractive scattering to the near-projectile products with the gold target. In the second experiment the excitation energy of primary projectile fragments from peripheral nuclear reactions at intermediate energies was carried out at the NSCL. Sodium, neon and fluorine isotopes produced by the fragmentation of a neutron-rich 32Mg beam by a beryllium target were observed in a magnetic spectrometer in coincidence with fast neutrons detected using the Modular Neutron Array (MoNA). A new technique based on an analysis of the observed neutron multiplicity distributions was used to estimate the excitation energy and mass of the precursor intermediate products for the first time. A strong correlation between the neutron multiplicity and the total mass loss was observed indicating that large excitation energies were created in the prefragments by the initial collision. These findings are generally consistent with the internuclear cascade model of the collision dynamics but not with macroscopic abrasion-ablation models.

  3. Searching for isovector signatures in the neutron-rich oxygen and calcium isotopes

    Directory of Open Access Journals (Sweden)

    Wei-Chia Chen

    2015-09-01

    Full Text Available We search for potential isovector signatures in the neutron-rich oxygen and calcium isotopes within the framework of a relativistic mean-field theory with an exact treatment of pairing correlations. To probe the isovector sector we calibrate a few relativistic density functionals using the same isoscalar constraints but with one differing isovector assumption. It is found that under certain conditions, the isotopic chain in oxygen can be made to terminate at the experimentally observed 24O isotope and in the case of the calcium isotopes at 60Ca. To produce such behavior, the resulting symmetry energy must be soft, with predicted values for the symmetry energy and its slope at saturation density being J=(30.92±0.47 MeV and L=(51.0±1.5 MeV, respectively. As a consequence, the neutron-skin thickness of 208Pb is rather small: Rskin208=(0.161±0.011 fm. This same model—labeled “FSUGarnet”—predicts R1.4=(13.0±0.1 km for the radius of a “canonical” 1.4M⊙ neutron star, yet is also able to support a two-solar-mass neutron star.

  4. Isomers in neutron-rich A ∼ 190 nuclides from 208Pb fragmentation

    International Nuclear Information System (INIS)

    Rykaczewski, Krzysztof Piotr; Caamano, M.; Banu, A.; Walker, P.M.; Morton, N.H.; Regan, P. H.; Regan, Patrick H; Pfutzner, M.; Podolyak, Zs.; Gerl, J.; Hellstrom, M.; Mayet, P.; Miernik, K.; Mineva, M.N.; Aprahamian, A.; Benlliure, J.; Bruce, A.M.; Butler, P.A.; Cortina Gil, D.; Cullen, D.M.; Doring, J.; Enqvist, T.; Fox, C.; Garces Narro, J.; Geissel, H.; Gelletly, W.; Giovinazzo, J.; Gorska, M.; Grawe, H.; Grzywacz, R.; Kleinbohl, A.; Korten, W.; Lewitowicz, M.; Lucas, R.; Mach, H.; O'Leary, C.D.; De Oliveira, F.; Pearson, C.J.; Rejmund, F.

    2004-01-01

    Relativistic projectile fragmentation of 208 Pb has been used to produce isomers in neutron-rich, A ∼ 190 nuclides. A forward-focusing spectrometer provided ion-by-ion mass and charge identification. The detection of gamma-rays emitted by stopped ions has led to the assignment of isomers in 188 Ta, 190 W, 192 Re, 193 Re, 195 Os, 197 Ir, 198 Ir, 200 Pt, 201 Pt, 202 Pt and 203 Au, with half-lives ranging from approximately 10 ns to 1 ms. Tentative isomer information has been found also for 174 Er, 175 Er, 185 Hf, 191 Re, 194 Re and 199 Ir. In most cases, time-correlated, singles gamma-ray events provided the first spectroscopic data on excited states for each nuclide. In 200 Pt and 201 Pt, the assignments are supported by gamma-gamma coincidences. Isomeric ratios provide additional information, such as half-life and transition energy constraints in particular cases. The level structures of the platinum isotopes are discussed, and comparisons are made with isomer systematics

  5. Isomer-delayed gamma-ray spectroscopy of neutron-rich 166Tb

    Science.gov (United States)

    Gurgi, L. A.; Regan, P. H.; Söderström, P.-A.; Watanabe, H.; Walker, P. M.; Podolyák, Zs.; Nishimura, S.; Berry, T. A.; Doornenbal, P.; Lorusso, G.; Isobe, T.; Baba, H.; Xu, Z. Y.; Sakurai, H.; Sumikama, T.; Catford, W. N.; Bruce, A. M.; Browne, F.; Lane, G. J.; Kondev, F. G.; Odahara, A.; Wu, J.; Liu, H. L.; Xu, F. R.; Korkulu, Z.; Lee, P.; Liu, J. J.; Phong, V. H.; Yagi, A.; Zhang, G. X.; Alharbi, T.; Carroll, R. J.; Chae, K. Y.; Dombradi, Zs.; Estrade, A.; Fukuda, N.; Griffin, C.; Ideguchi, E.; Inabe, N.; Kanaoka, H.; Kojouharov, I.; Kubo, T.; Kubono, S.; Kurz, N.; Kuti, I.; Lalkovski, S.; Lee, E. J.; Lee, C. S.; Lotay, G.; Moon, C. B.; Nishizuka, I.; Nita, C. R.; Patel, Z.; Roberts, O. J.; Schaffner, H.; Shand, C. M.; Suzuki, H.; Takeda, H.; Terashima, S.; Vajta, Zs.; Kanaya, S.; Valiente-Dobòn, J. J.

    2017-09-01

    This short paper presents the identification of a metastable, isomeric-state decay in the neutron-rich odd-odd, prolate-deformed nucleus 166Tb. The nucleus of interest was formed using the in-flight fission of a 345 MeV per nucleon 238U primary beam at the RIBF facility, RIKEN, Japan. Gamma-ray transitions decaying from the observed isomeric states in 166Tb were identified using the EURICA gamma-ray spectrometer, positioned at the final focus of the BigRIPS fragments separator. The current work identifies a single discrete gamma-ray transition of energy 119 keV which de-excites an isomeric state in 166Tb with a measured half-life of 3.5(4) μs. The multipolarity assignment for this transition is an electric dipole and is made on the basis internal conversion and decay lifetime arguments. Possible two quasi-particle Nilsson configurations for the initial and final states which are linked by this transition in 166Tb are made on the basis of comparison with Blocked BCS Nilsson calculations, with the predicted ground state configuration for this nucleus arising from the coupling of the v(1-/2)?[521] and ? π(3+/2) Nilsson orbitals.

  6. Decay studies and mass measurements on isobarically pure neutron-rich Hg and Tl isotopes

    CERN Multimedia

    Schweikhard, L C; Savreux, R P; Hager, U D K; Beck, D; Blaum, K

    2007-01-01

    We propose to perform mass measurements followed by $\\beta$- and $\\gamma$-decay studies on isobarically pure beams of neutron-rich Hg and Tl isotopes, which are very poorly known due to a large contamination at ISOL-facilities with surface-ionised francium. The aim is to study the binding energies of mother Hg and Tl nuclides, as well as the energies, spins and parities of the excited and ground states in the daughter Tl and Pb isotopes. The proposed studies will address a new subsection of the nuclear chart, with Z 126, where only 9 nuclides have been observed so far. Our studies will provide valuable input for mass models and shell-model calculations: they will probe the proton hole-neutron interaction and will allow to refine the matrix elements for the two-body residual interaction. Furthermore, they also give prospects for discovering new isomeric states or even new isotopes, for which the half-lives are predicted in the minute- and second-range.\\\\ To reach the isobaric purity, the experiments will be p...

  7. Coulomb Excitation of a Neutron-Rich $^{88}$Kr Beam Search for Mixed Symmetry States

    CERN Multimedia

    Andreoiu, C; Napiorkowski, P J; Iwanicki, J S

    2002-01-01

    We propose to use the ISOLDE/REX/MINIBALL/CD set-up to perform a Coulomb Excitation experiment with a $^{88}$Kr radioactive beam. The motivation includes a search for $Mixed$ $Symmetry$ states predicted by the IBM-2 model, gathering more spectroscopy data about the $^{88}$Kr nucleus and extending shape coexistence studies (performed previously by the proposers for neutron-deficient Kr isotopes) to the neutron-rich side. The proposed experiment will provide data complementary to the Coulomb Excitation of a relativistic $^{88}$Kr beam proposed by D. Tonev et al. for a RISING experiment. A total of 12 days of beam time is necessary for the experiment, equally divided into two runs. One run with a 2.2 MeV/A beam energy on a $^{48}$Ti target and a second run with the maximum available REX energy of 3.1 MeV/A on a $^{208}$Pb target are requested. Using either a UC$_{x}$ or ThC$_{x}$ fissioning primary target coupled with a plasma source by a cooled transfer line seems to be the best choice for the proposed experime...

  8. Beta-transition properties for neutron-rich Sn and Te isotopes by ...

    Indian Academy of Sciences (India)

    β transition properties in near double close shell nuclei have been studied using ... MeV) of the shell model states near Fermi surface for. 132. Sn. Neutron hole. Proton particle. Level. Exp. [18]. This work. [17]. Level. Exp. [18]. This work. [17] ... bour odd–odd nuclei and the β decay log(ft) values have been calculated within.

  9. Decay Study for the very Neutron-Rich Sn Nuclides, $^{135-140}$Sn Separated by Selective Laser Ionization

    CERN Multimedia

    2002-01-01

    %IS378 %title\\\\ \\\\ In this investigation, we wish to take advantage of chemically selective laser ionization to separate the very-neutron-rich Sn nuclides and determine their half-lives and delayed-neutron branches (P$_{n}$) using the Mainz $^{3}$He-delayed neutron spectrometer and close-geometry $\\gamma$-ray spectroscopy system. The $\\beta$-decay rates are dependent on a number of nuclear structure factors that may not be well described by models of nuclear structure developed for nuclides near stability. Determination of these decay properties will provide direct experimental data for r-process calculations and test the large number of models of nuclear structure for very-neutron rich Sn nuclides now in print.

  10. Beta-decay properties of the neutron-rich $^{94-99}$Kr and $^{142-147}$Xe isotopes

    CERN Document Server

    Bergmann, U C; Riisager, K; Weissman, L; Auböck, G; Cederkäll, J; Fraile-Prieto, L M; Fynbo, H O U; Gausemel, H; Jeppesen, H B; Köster, U; Kratz, K L; Møller, P; Nilsson, T; Pfeiffer, B; Simon, H; Van de Vel, K; Äystö, J

    2003-01-01

    Beta-decay half-lives and delayed-neutron emission probabilities of the neutron-rich noble-gas isotopes $^{94-99}$Kr and $^{142- 147}$Xe have been measured at the PSB-ISOLDE facility at CERN. The results are compared to QRPA shell-model predictions and are used in dynamic calculations of r-process abundances of Kr and Xe isotopes.

  11. Recent Progress in Constraining the Equation of State of Dense Neutron-Rich Nuclear Matter with Heavy-Ion Reactions

    International Nuclear Information System (INIS)

    Li Baoan; Chen Liewen; Wen Dehua; Xiao Zhigang; Xu Chang; Yong Gaochan; Zhang Ming

    2010-01-01

    The nuclear symmetry energy E sym (ρ) is the most uncertain part of the Equation of State (EOS) of dense neutron-rich nuclear matter. In this talk, we discuss the underlying physics responsible for the uncertain E sym (ρ) especially at supra-saturation densities, the circumstantial evidence for a super-soft E sym (ρ) from analyzing π - /π + ratio in relativistic heavy-ion collisions and its impacts on astrophysics and cosmology.

  12. Pairing-energy coefficients of neutron-rich fragments in spallation reactions

    Science.gov (United States)

    Niu, Fei; Ma, Chun-Wang

    2018-02-01

    The ratio of pairing-energy coefficient to temperature (a p/T) of neutron-rich fragments produced in spallation reactions has been investigated by adopting an isobaric yield ratio method deduced in the framework of a modified Fisher model. A series of spallation reactions, 0.5A and 1A GeV 208Pb + p, 1A GeV 238U + p, 0.5A GeV 136Xe + d, 0.2A, 0.5A and 1A GeV 136Xe + p, and 56Fe + p with incident energy ranging from 0.3A to 1.5A GeV, has been analysed. An obvious odd-even staggering is shown in the fragments with small neutron excess (I ≡ N-Z), and in the relatively small-A fragments which have large I. The values of a p/T for the fragments, with I from 0 to 36, have been found to be in a range from ‑4 to 4, and most values of a p/T fall in the range from ‑1 to 1. It is suggested that a small pairing-energy coefficient should be considered in predicting the cross sections of fragments in spallation reactions. It is also concluded that the method proposed in this article is not good for fragments with A/A s > 85% (where A s is the mass number of the spallation system). Supported by National Natural Science Foundation of China (U1732135), Natural Science Foundation of Henan Province (162300410179) and Henan Normal University for the Excellent Youth (154100510007)

  13. 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

  14. Light unstable nuclei in the continuum

    International Nuclear Information System (INIS)

    Kato, Kiyoshi

    2000-01-01

    It is discussed that the complex scaling method is one of the most available frameworks to solve many body resonances. As the recent developments of the complex scaling method, we present several ways to analyse the properties of resonant states; the matrix elements associated with resonant states, the extended completeness relation and partial widths of resonances. We also show the discussions on the binding mechanism and excited resonant structure of the Borromean systems 4 He+n+n and 9 Li+n+n. It is shown that the pairing correlation between valence neutrons and among core neutrons plays an important role in neutron-rich nuclei. (author)

  15. Neutron halo in deformed nuclei

    International Nuclear Information System (INIS)

    Zhou Shangui; Meng Jie; Ring, P.; Zhao Enguang

    2010-01-01

    Halo phenomena in deformed nuclei are investigated within a deformed relativistic Hartree Bogoliubov (DRHB) theory. These weakly bound quantum systems present interesting examples for the study of the interdependence between the deformation of the core and the particles in the halo. Contributions of the halo, deformation effects, and large spatial extensions of these systems are described in a fully self-consistent way by the DRHB equations in a spherical Woods-Saxon basis with the proper asymptotic behavior at a large distance from the nuclear center. Magnesium and neon isotopes are studied and detailed results are presented for the deformed neutron-rich and weakly bound nucleus 44 Mg. The core of this nucleus is prolate, but the halo has a slightly oblate shape. This indicates a decoupling of the halo orbitals from the deformation of the core. The generic conditions for the occurrence of this decoupling effects are discussed.

  16. Study of ground-state configuration of neutron-rich aluminium isotopes through electromagnetic excitation

    International Nuclear Information System (INIS)

    Chakraborty, S.; Datta Pramanik, U.; Chatterjee, S.

    2013-01-01

    The region of the nuclear chart around neutron magic number, N∼20 and proton number (Z), 10≤ Z≤12 is known as the Island of Inversion. The valance neutron(s) of these nuclei, even in their ground state, are most likely occupying the upper pf orbitals which are normally lying above sd orbitals, N∼20 shell closure. Nuclei like 34,35 Al are lying at the boundary of this Island of Inversion. Little experimental information about their ground state configuration are available in literature

  17. Study of the elastic scattering and of the (p,n) charge exchange reaction with neutron-rich light exotic beams; Etude de la diffusion elastique et de la reaction d`echange de charge (p,n) avec des faisceaux exotiques legers riches en neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Cortina Gil, D.

    1996-07-05

    We have measured at GANIL, with the high resolution spectrometer SPEG, the elastic scattering of several neutron rich secondary beams ({sup 6}He, {sup 10}Be and {sup 11}Be) on a polypropylene target and the charge exchange reaction p({sup 6}He, {sup 6}Li)n. These exotic beams were produced by nuclear fragmentation and re-focalized with the SISSI device (superconducting solenoids). The signature of a halo structure in these nuclei has been analysed. Special attention has been paid to several aspects of the associated calculations namely, the proton and neutron density distributions and the small binding energy for the last nucleons in these exotic nuclei. Break-up mechanisms are seen to play an important role in these nuclei. 100 refs.

  18. Spectroscopical study of the yrast and yrare structure in far-from-stability nuclei

    International Nuclear Information System (INIS)

    Hoellinger Fabien

    1999-01-01

    The nuclear structure study of neutron-rich nuclei was realized with the EUROGAM II array in two different experiments. The first study consisted in the analysis of the product of spontaneous fission of 248 Cm. Three neutron-rich cerium isotopes 147,149,151 Ce were analyzed. A level scheme for 151 Ce is presented for the first time. The yrast structure of the three nuclei does not show alternative parity bands as expected in this region of octupole deformations. We studied the rotational structure of the bands and this leads to suggest Nilsson configurations to some of them. The aim of this second experiment was the study of the nuclei 99 Mo, 101 Tc, 103 Ru. The three nuclei are situated on the neutron-rich side of the nuclear chart and are produced as fission fragments of a heavy-ion induced reaction. Some bands are extended to higher spins and some new bands are observed. The structure of the rotational bands is interpreted by means of the Hartree-Fock-Bogolyubov model. A last experiment intended to study the structure of the proton-rich nucleus 223 Pa has been achieved with the JURO+RITU array located at Jyvaeskylae (Finland). In this proton-rich actinide region, the nuclei develop octupole features around Z≅88, N≅132. The analysis of this experiment leads to the first assignment of gamma transitions to the 223 Pa. (author)

  19. Laser Spectroscopy Study on the Neutron-Rich and Neutron-Deficient Te Isotopes

    CERN Multimedia

    2002-01-01

    We propose to perform laser spectroscopy measurements on the Te isotopes. This will give access to fundamental properties of the ground and rather long-lived isomeric states such as the change in the mean square charge radius ($\\delta\\langle$r$^2_c\\rangle$) and the nuclear moments. For these medium-mass isotopes, at this moment the optical resolution obtained with RILIS is not high enough to perform isotope shift measurements. Thus we will use the COMPLIS experimental setup which allows Resonant Ionization Spectroscopy (RIS) on laser desorbed atoms. The 5p$^{4}$ $^{3}$P$_{2} \\rightarrow$ 5p$^{3}$ 6s $^{3}$S$_{1}$ and 5p$^{4}$ $^{3}$P$_{2} \\rightarrow$ 5p$^{3}$ 6s $^{5}$S$_{2}$ optical transitions have been used to perform, on the stable Te isotopes, the tests required by the INTC committee. For this purpose stable-ion sources have been built and Te isotopes have been delivered as stable beams by the injector coupled to the COMPLIS setup. ISOLDE offers the opportunity for studying the Te isotope series over a ...

  20. Constraining the EOS of Neutron-Rich Nuclear Matter and Properties of Neutron Stars with Heavy-Ion Reactions

    International Nuclear Information System (INIS)

    Li Baoan; Worley, Aaron; Chen, L.-W.; Ko, Che Ming; Krastev, Plamen G.; Wen Dehua; Xiao Zhigang; Zhang Ming; Xu Jun; Yong Gaochan

    2009-01-01

    Heavy-ion reactions especially those induced by radioactive beams provide useful information about the density dependence of the nuclear symmetry energy, thus the Equation of State of neutron-rich nuclear matter, relevant for many astrophysical studies. The latest developments in constraining the symmetry energy at both sub- and supra-saturation densities from analyses of the isopsin diffusion and the π - /π + ratio in heavy-ion collisions using the IBUU04 transport model are discussed. Astrophysical ramifications of the partially constrained symmetry energy on properties of neutron star crusts, gravitational waves emitted by deformed pulsars and the w-mode oscillations of neutron stars are presented briefly.

  1. Relativistic exotic nuclei as projectile beams. New perspectives of studies on the properties of nuclei

    International Nuclear Information System (INIS)

    Geissel, H.

    1997-03-01

    Examinations of the production cross-sections and the kinematics permitted refinement of model concepts of the peripheral reactions in exotic nuclei at energies from 100 to 1000 A MeV. Due to the strong selectivity and resolution achieved it was possible to discover a large number of novel isotopes at the fragment separator FRS, despite the relatively low projectile beam intensities of the SIS. The two twice magic nuclei found, Ni 78 and Sn 100, are particularly interesting, as they could not be measured so far with other experimental systems. Fission of relativistic uranium ions proved to be a particularly successful process yielding many medium-heavy, neutron-rich nuclei. Insight into the structure of light neutron halos could be improved. The superlarge spatial dimensions of the nuclear halos is discussed. (orig./CB) [de

  2. Saturation of Deformation and Identical Bands in Very-Neutron Rich Sr Isotopes

    CERN Multimedia

    2002-01-01

    The present proposal aims at establishing nuclear properties in an isotopic chain showing unique features. These features include the saturation of ground state deformation at its onset and the existence of ground state identical bands in neighbouring nuclei with the same deformation. The measurements should help to elucidate the role played by the proton-neutron residual interaction between orbitals with large spatial overlap, i.e. $\\pi g _{9/2} \

  3. Onset of collectivity in neutron-rich Sr and Kr isotopes: Prompt spectroscopy after Coulomb excitation at REX-ISOLDE, CERN

    Directory of Open Access Journals (Sweden)

    Clément E.

    2013-12-01

    Full Text Available A rapid onset of quadrupole deformation is known to occur around the neutron number 60 in the neutron-rich Zr and Sr isotopes. This shape change has made the neutron-rich A = 100 region an active area of experimental and theoretical studies for many decades now. We report in this contribution new experimental results in the neutron rich 96,98Sr investigated by safe Coulomb excitation of radioactive beams at the REX-ISOLDE facility, CERN. Reduced transition probabilities and spectroscopic quadrupole moments have been extracted from the differential Coulomb excitation cross section supporting the scenario of shape coexistence/change at N = 60. Future perspectives are presented including the recent experimental campaign performed at ILL-Grenoble.

  4. Study of the production of neutron-rich isotope beams issuing from fissions induced by fast neutrons; Etude de la production de faisceaux riches en neutrons par fission induite par neutrons rapides

    Energy Technology Data Exchange (ETDEWEB)

    Lau, Ch

    2000-09-15

    This work is a contribution to the PARRNe project (production of radioactive neutron-rich isotopes). This project is based on the fission fragments coming from the fission of 238-uranium induced by fast neutrons. The fast neutron flux is produced by the collisions of deutons in a converter. Thick targets of uranium carbide and liquid uranium targets have been designed in order to allow a quick release of fission fragments. A device, able to trap on a cryogenic thimble rare gas released by the target, has allowed the production of radioactive nuclei whose half-life is about 1 second. This installation has been settled to different deuton accelerators in the framework of the European collaboration SPIRAL-2. A calibration experiment has proved the feasibility of fixing an ISOL-type isotope separator to a 15 MV tandem accelerator, this installation can provide 500 nA deutons beams whose energy is 26 MeV and be a valuable tool for studying fast-neutron induced fission. Zinc, krypton, rubidium, cadmium, iodine, xenon and cesium beams have been produced in this installation. The most intense beams reach 10000 nuclei by micro-coulomb for 26 MeV deutons. An extra gain of 2 magnitude orders can be obtained by using a more specific ion source and by increasing the thickness of the target. Another extra gain of 2 magnitude orders involves 100 MeV deutons.

  5. Energy dependence of the optical potential of weakly and tightly bound nuclei as projectiles on a medium-mass target

    International Nuclear Information System (INIS)

    Figueira, J. M.; Arazi, A.; Carnelli, P.; Heimann, D. Martinez; Negri, A. E.; Pacheco, A. J.; Niello, J. O. Fernandez; Capurro, O. A.; Fimiani, L.; Marti, G. V.; Lubian, J.; Monteiro, D. S.; Gomes, P. R. S.

    2010-01-01

    Angular distributions for the elastic scattering of the weakly bound 6,7 Li+ 144 Sm systems were measured with high accuracy at bombarding energies from 85% up to 170% of the Coulomb barrier. An optical model analysis was performed, and the relevant parameters of the real and imaginary parts of the optical potential were extracted. The results are compared with those previously published for the tightly bound 12 C+ 144 Sm and 16 O+ 144 Sm systems. The usual threshold anomaly observed in the behavior of the potential of tightly bound systems was not observed for either weakly bound system. This absence is attributed to the repulsion due to breakup coupling which cancels the attraction arising from couplings with bound channels.

  6. Reaction cross-sections and reduced strong absorption radii of nuclei in the vicinity of closed shells N=20 and N=28

    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

  7. Population of Nuclei Via 7Li-Induced Binary Reactions

    Energy Technology Data Exchange (ETDEWEB)

    Clark, Rodney M.; Phair, Larry W.; Descovich, M.; Cromaz, Mario; Deleplanque, M.A.; Fall on, Paul; Lee, I-Yang; Macchiavelli, A.O.; McMahan, Margaret A.; Moretto, Luciano G.; Rodriguez-Vieitez, E.; Sinha,Shrabani; Stephens, Frank S.; Ward, David; Wiedeking, Mathis

    2005-08-08

    The authors have investigated the population of nuclei formed in binary reactions involving {sup 7}Li beams on targets of {sup 160}Gd and {sup 184}W. The {sup 7}Li + {sup 184}W data were taken in the first experiment using the LIBERACE Ge-array in combination with the STARS Si {Delta}E-E telescope system at the 88-Inch Cyclotron of the Lawrence Berkeley National Laboratory. By using the Wilczynski binary transfer model, in combination with a standard evaporation model, they are able to reproduce the experimental results. This is a useful method for predicting the population of neutron-rich heavy nuclei formed in binary reactions involving beams of weakly bound nuclei formed in binary reactions involving beams of weakly bound nuclei and will be of use in future spectroscopic studies.

  8. Production of neutron-rich isotopes by cold fragmentation in the reaction 197Au + Be at 950 A MeV

    International Nuclear Information System (INIS)

    Benlliure, J.; Pereira, J.; Schmidt, K.H.; Cortina-Gil, D.; Enqvist, T.; Heinz, A.; Junghans, A.R.; Farget, F.; Taieb, J.

    1999-09-01

    The production cross sections and longitudinal-momentum distributions of very neutron-rich isotopes have been investigated in the fragmentation of a 950 A MeV 179 Au beam in a beryllium target. Seven new isotopes ( 193 Re, 194 Re, 191 W, 192 W, 189 Ta, 187 Hf and 188 Hf) and the five-proton-removal channel were observed for the first time. The reaction mechanism leading to the formation of these very neutron-rich isotopes is explained in terms of the cold-fragmentation process. An analytical model describing this reaction mechanism is presented. (orig.)

  9. Gamma spectroscopy of fission fragments using a Eurogam multidetector: search of octupolar relations in the neutron rich Xe isotopes; Spectroscopie gamma des fragments de fission a l`aide du multidetecteur Eurogam: recherche des correlations octupolaires dans les isotopes du Xe riches en neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Bentaleb, M.

    1995-06-01

    A search for octupole deformation in neutron rich Xe isotopes has been conducted through gamma-ray of secondary fragments produced in the spontaneous fission of {sup 248} Cm. The spectrometer consisted of Eurogam 1 array and a set of LEPS detectors. Clean one-dimensional spectra were extracted from a cubic data array and gated matrices. This technique enabled the construction of level schemes for Xe isotopes with masses ranging from 138 to 144. None of the level schemes exhibit an alternating parity quasimolecular band, a feature usually encountered in nuclei with stable octupole deformation. For several isotopes, structures are observed in the level schemes which indicates that the nuclei are octupole soft. (author). 48 refs., 52 figs., 4 tabs.

  10. Precision mass measurements of neutron-rich Co isotopes beyond N =40

    Science.gov (United States)

    Izzo, C.; Bollen, G.; Brodeur, M.; Eibach, M.; Gulyuz, K.; Holt, J. D.; Kelly, J. M.; Redshaw, M.; Ringle, R.; Sandler, R.; Schwarz, S.; Stroberg, S. R.; Sumithrarachchi, C. S.; Valverde, A. A.; Villari, A. C. C.

    2018-01-01

    The region near Z =28 and N =40 is a subject of great interest for nuclear structure studies due to spectroscopic signatures in 68Ni suggesting a subshell closure at N =40 . Trends in nuclear masses and their derivatives provide a complementary approach to shell structure investigations via separation energies. Penning trap mass spectrometry has provided precise measurements for a number of nuclei in this region; however, a complete picture of the mass surfaces has so far been limited by the large uncertainty remaining for nuclei with N >40 along the iron (Z =26 ) and cobalt (Z =27 ) chains because these species are not available from traditional isotope separator online rare isotope facilities. The Low-Energy Beam and Ion Trap Facility at the National Superconducting Cyclotron Laboratory is the first and only Penning trap mass spectrometer coupled to a fragmentation facility and therefore presents the unique opportunity to perform precise mass measurements of these elusive isotopes. Here we present the first Penning trap measurements of Co,6968, carried out at this facility. Some ambiguity remains as to whether the measured values are ground-state or isomeric-state masses. A detailed discussion is presented to evaluate this question and to motivate future work. In addition, we perform ab initio calculations of ground-state and two-neutron separation energies of cobalt isotopes with the valence-space in-medium similarity renormalization group approach based on a particular set of two- and three-nucleon forces that predict saturation in infinite matter. We discuss the importance of these measurements and calculations for understanding the evolution of nuclear structure near 68Ni.

  11. p-sd Shell Gap Reduction in Neutron-Rich Systems and Cross-ShellExcitations in 20O

    Energy Technology Data Exchange (ETDEWEB)

    Wiedeking, M.; Tabor, S.L.; Pavan, J.; Volya, A.; Aguilar, A.L.; Calderin, I.J.; Campbell, D.B.; Cluff, W.T.; Diffenderfer, E.; Fridmann,J.; Hoffman, C.R.; Kemper, K.W.; Lee, S.; Riley, M.A.; Roeder, B.T.; Teal, C.; Tripathi, V.; Wiedenhover, I.

    2005-04-07

    Excited states in {sup 20}O were populated in the reaction {sup 10}Be({sup 14}C,{alpha}) at Florida State University (FSU). Charged particles were detected with a particle telescope consisting of 4 annularly segmented Si surface barrier detectors and {gamma} radiation was detected with the FSU {gamma} detector array. Five new states were observed below 6 MeV from the {alpha}-{gamma} and {alpha}-{gamma}-{gamma} coincidence data. Shell model calculations suggest that most of the newly observed states are core-excited 1p-1h excitations across the N=Z=8 shell gap. Comparisons between experimental data and calculations for the neutron-rich O and F isotopes imply a steady reduction of the p-sd shell gap as neutrons are added.

  12. Measurement of the magnetic moment of the 2$^{+}$ state in neutron-rich radioactive $^{72,74}$Zn using the transient field technique in inverse kinematics

    CERN Multimedia

    Kruecken, R; Speidel, K; Voulot, D; Neyens, G; Gernhaeuser, R A; Fraile prieto, L M; Leske, J

    We propose to measure the sign and magnitude of the g-factors of the first 2$^{+}$ states in radioactive neutron-rich $^{72,74}$Zn applying the transient field (TF) technique in inverse kinematics. The result of this experiment will allow to probe the $\

  13. Theoretical and experimental studies of the neutron rich fission product yields at intermediate energies

    Directory of Open Access Journals (Sweden)

    Äystö J.

    2012-02-01

    Full Text Available A new method to measure the fission product independent yields employing the ion guide technique and a Penning trap as a precision mass filter, which allows an unambiguous identification of the nuclides is presented. The method was used to determine the independent yields in the proton-induced fission of 232Th and 238U at 25 MeV. The data were analyzed with the consistent model for description of the fission product formation cross section at the projectile energies up to 100 MeV. Pre-compound nucleon emission is described with the two-component exciton model using Monte Carlo method. Decay of excited compound nuclei is treated within time-dependent statistical model with inclusion of the nuclear friction effect. The charge distribution of the primary fragment isobaric chain was considered as a result of frozen quantal fluctuations of the isovector nuclear density. The theoretical predictions of the independent fission product cross sections are used for normalization of the measured fission product isotopic distributions.

  14. Quasi-free one nucleon knockout reactions on neutron-rich oxygen isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Atar, Leyla; Aumann, Thomas [TU Darmstadt, Darmstadt (Germany); GSI, Darmstadt (Germany); Bertulani, Carlos [Texas A and M University-Commerce, Commerse (United States); Paschalis, Stefanos [TU Darmstadt, Darmstadt (Germany); Nociforo, Chiara [GSI, Darmstadt (Germany); Collaboration: R3B-Collaboration

    2015-07-01

    Recent experiments have shown a reduction of spectroscopic strengths to about 60-70% for stable nuclei. When going to drip lines this tendency is changing, loosely bound nucleons have spectroscopic strengths close unity while deeply bound nucleons have a large reduction of the strength. We aim to make a systematic study of spectroscopic factors (SF) of the Oxygen isotopes using quasi-free (p,2p) and (p,pn) knockout reactions in inverse kinematics. Quasi-free knockout reactions are a direct tool to study the occupancy and the location of valance and deeply bound single particle states. The Oxygen isotopes offer a large variation of separation energies which will allow us to obtain a qualitative and quantitative understanding of SF in a large variation of isospin asymmetry. For this we performed an experiment at the R3B-LAND setup at the GSI with secondary beams containing {sup 14-24}O. The {sup 16-18}O and {sup 21-23}O isotopes have been analyzed and the preliminary results will be presented. The results include the partial cross sections, gamma ray spectra of the residual fragments in coincidence, and the SF obtained via comparison with theory.

  15. Study of drip line nuclei through two-step fragmentation

    International Nuclear Information System (INIS)

    Stanoiu, M.; Becker, F.; Lewitowicz, M.; Azaiez, F.; Bourgeois, C.; Ibrahim, F.; Belleguic, M.; Borcea, C.; Mrazek, J.; Brown, B.A.; Dlouhy, Z.; Dombradi, Z.; Fueloep, Z.; Krasznahorkay, A.; Grawe, H.; Mayet, P.; Grevy, S.; Kerek, A.; Marel, H. van der; Lukyanov, S.; Mandal, S.; Guillemaud-Mueller, D.; Negoita, F.; Penionzhkevich, Y.E.; Podolyak, Z.; Roussel-Chomaz, P.; Saint Laurent, M.G.; Savajols, H.; Sorlin, O.; Sletten, G.; Sohler, D.; Timar, J.; Timis, C.; Yamamoto, A.

    2004-01-01

    We have studied the structure of light neutron-rich nuclei around N = 16 by employing the in-beam γ-ray spectroscopy technique using the fragmentation of secondary beams of 25,26 Ne, 27,28 Na and 29,30 Mg isotopes. This secondary-beam ''cocktail'' was obtained by the fragmentation of a 36 S beam at 77.5 MeV.A by the SISSI/GANIL facility. By a second-step fragmentation, we have measured γ-ray-residue coincidences in 17-20 C and 23,24 O and described the obtained levels in the framework of the shell model. (orig.)

  16. γγ-coincidence in the neutron rich nucleus 25F

    International Nuclear Information System (INIS)

    Vajta, Zs.; Sohler, D.; Dombradi, Zs.; Azaiez, F.; Belleguic, M.; Brown, B.A.; Becker, F.

    2012-01-01

    Complete text of publication follows. The 25 F isotope, having a valence proton in addition to the doubly closed shell 24 O core, is expected to have a rather simple structure: its energy spectrum can be described as a few single proton states coupled to the ground and excited states of the neighboring oxygen nucleus, 24 O. However, states arising from cross shell excitations may also be present. According to theoretical calculations intruder states may appear in 25 F somewhat above the neutron separation energy. To see if any of these states is bound the structure of 25 F was studied at GANIL by in-beam γ-spectroscopic technique in the double step fragmentation reaction. In the experiment the primary beam of 36 S delivered by the two GANIL cyclotrons at an energy of 77.5 MeVA and an intensity of 400 pnA hit a carbon target of 348 mg/cm 2 thickness placed in the SISSI device. The produced nuclei were selected through the Alpha spectrometer. The secondary beam was mainly composed of 24 F, 25,26 Ne, 27,28 Na and 29,30 Mg. The fragments produced by reactions of the secondary beam on an 'active' target made of a plastic scintillator sandwiched by two carbon foils were collected and identified at the focal plane of the SPEG spectrometer by the combined use of ΔE, E, TOF information. 74 BaF 2 scintillators surrounding the secondary target detected the γ rays from the fragments. The γ-spectra were corrected for the Doppler-shift caused by the large fragment velocity. As the detectors were closely packed, the γ rays could easily scatter from one detector to another. To decrease the background caused by the scattered particles, we used the array in anti-Compton mode. On the basis of the analysis of γ-ray spectrum taken for 25 F 6 γ lines are assigned to the studied nucleus between 750 and 4200 keV. To help the level scheme construction, γγ-coincidence matrices were created. Putting a gate on the most intense 1720-keV γ line, it was found to be in coincidence with

  17. From laser particle acceleration to the synthesis of extremely neutron rich isotopes via the novel fission-fusion mechanism

    International Nuclear Information System (INIS)

    Thirolf, P. G.

    2015-01-01

    High-power, short pulse lasers have emerged in the last decade as attractive tools for accelerating charged particles (electrons, ions) to high energies over mm-scale acceleration lengths, thus promising to rival conventional acceleration techniques in the years ahead. In the first part of the article, the principles of laser-plasma interaction as well as the techniques and the current status of the acceleration of electron and ion beams will be briefly introduced. In particular with the upcoming next generation of multi-PW class laser systems, such as the one under construction for the ELI-Nuclear Physics project in Bucharest (ELI-NP), very efficient acceleration mechanisms for brilliant ion beams like radiation pressure acceleration (RPA) come into reach. Here, ultra-dense ion beams reaching solid-state density can be accelerated from thin target foils, exceeding the density of conventionally accelerated ion beams by about 14 orders of magnitude. This unique property of laser-accelerated ion beams can be exploited to explore the scenario of a new reaction mechanism called ‘fission-fusion’, which will be introduced in the second part of the article. Accelerating fissile species (e.g. 232 Th) towards a second layer of the same material will lead to fission both of the beam-like and target-like particles. Due to the close to solid-state density of the accelerated ion bunches, fusion may occur between neutron-rich (light) fission products. This may open an access path towards extremely neutron-rich nuclides in the vicinity of the N=126 waiting point of the astrophysical r process. ‘Waiting points’ at closed nucleon shells play a crucial role in controlling the reaction rates. However, since most of the pathway of heavy-element formation via the rapid-neutron capture process (r-process) runs in ‘terra incognita’ of the nuclear landscape, in particular the waiting point at N=126 is yet unexplored and will remain largely inaccessible to conventional nuclear

  18. 94 β-Decay Half-Lives of Neutron-Rich _{55}Cs to _{67}Ho: Experimental Feedback and Evaluation of the r-Process Rare-Earth Peak Formation.

    Science.gov (United States)

    Wu, J; Nishimura, S; Lorusso, G; Möller, P; Ideguchi, E; Regan, P-H; Simpson, G S; Söderström, P-A; Walker, P M; Watanabe, H; Xu, Z Y; Baba, H; Browne, F; Daido, R; Doornenbal, P; Fang, Y F; Gey, G; Isobe, T; Lee, P S; Liu, J J; Li, Z; Korkulu, Z; Patel, Z; Phong, V; Rice, S; Sakurai, H; Sinclair, L; Sumikama, T; Tanaka, M; Yagi, A; Ye, Y L; Yokoyama, R; Zhang, G X; Alharbi, T; Aoi, N; Bello Garrote, F L; Benzoni, G; Bruce, A M; Carroll, R J; Chae, K Y; Dombradi, Z; Estrade, A; Gottardo, A; Griffin, C J; Kanaoka, H; Kojouharov, I; Kondev, F G; Kubono, S; Kurz, N; Kuti, I; Lalkovski, S; Lane, G J; Lee, E J; Lokotko, T; Lotay, G; Moon, C-B; Nishibata, H; Nishizuka, I; Nita, C R; Odahara, A; Podolyák, Zs; Roberts, O J; Schaffner, H; Shand, C; Taprogge, J; Terashima, S; Vajta, Z; Yoshida, S

    2017-02-17

    The β-decay half-lives of 94 neutron-rich nuclei ^{144-151}Cs, ^{146-154}Ba, ^{148-156}La, ^{150-158}Ce, ^{153-160}Pr, ^{156-162}Nd, ^{159-163}Pm, ^{160-166}Sm, ^{161-168}Eu, ^{165-170}Gd, ^{166-172}Tb, ^{169-173}Dy, ^{172-175}Ho, and two isomeric states ^{174m}Er, ^{172m}Dy were measured at the Radioactive Isotope Beam Factory, providing a new experimental basis to test theoretical models. Strikingly large drops of β-decay half-lives are observed at neutron-number N=97 for _{58}Ce, _{59}Pr, _{60}Nd, and _{62}Sm, and N=105 for _{63}Eu, _{64}Gd, _{65}Tb, and _{66}Dy. Features in the data mirror the interplay between pairing effects and microscopic structure. r-process network calculations performed for a range of mass models and astrophysical conditions show that the 57 half-lives measured for the first time play an important role in shaping the abundance pattern of rare-earth elements in the solar system.

  19. Exotic nuclei

    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.)

  20. Identification of New Neutron-Rich Isotopes in the Rare-Earth Region Produced by 345 MeV/nucleon 238U

    Science.gov (United States)

    Fukuda, Naoki; Kubo, Toshiyuki; Kameda, Daisuke; Inabe, Naohito; Suzuki, Hiroshi; Shimizu, Yohei; Takeda, Hiroyuki; Kusaka, Kensuke; Yanagisawa, Yoshiyuki; Ohtake, Masao; Tanaka, Kanenobu; Yoshida, Koichi; Sato, Hiromi; Baba, Hidetada; Kurokawa, Meiko; Ohnishi, Tetsuya; Iwasa, Naohito; Chiba, Ayuko; Yamada, Taku; Ideguchi, Eiji; Go, Shintaro; Yokoyama, Rin; Fujii, Toshihiko; Nishibata, Hiroki; Ieki, Kazuo; Murai, Daichi; Momota, Sadao; Nishimura, Daiki; Sato, Yoshiteru; Hwang, Jongwon; Kim, Sunji; Tarasov, Oleg B.; Morrissey, David J.; Simpson, Gary

    2018-01-01

    A search for new isotopes in the neutron-rich rare-earth region has been carried out using a 345 MeV/nucleon 238U beam at the RIKEN Nishina Center RI Beam Factory. Fragments produced were analyzed and identified using the BigRIPS in-flight separator. We observed a total of 29 new neutron-rich isotopes: 153Ba, 154,155,156La, 156,157,158Ce, 156,157,158,159,160,161Pr, 162,163Nd, 164,165Pm, 166,167Sm, 169Eu, 171Gd, 173,174Tb, 175,176Dy, 177,178Ho, and 179,180Er.

  1. New neutron-rich isotopes in the scandium-to-nickel region, produced by fragmentation of a 500 MeV/u 86Kr beam

    International Nuclear Information System (INIS)

    Weber, M.; Geissel, H.; Keller, H.; Magel, A.; Muenzenberg, G.; Nickel, F.; Pfuetzner, M.; Piechaczek, A.; Roeckl, E.; Rykaczewski, K.; Schall, I.; Suemmerer, K.; Donzaud, C.; Guillemaud-Mueller, D.; Mueller, A.C.; Stephan, C.; Tassan-Got, L.; Dufour, J.P.; Pravikoff, M.; Grewe, A.; Voss, B.; Vieira, D.J.

    1991-10-01

    We have measured production cross-sections of the new neutron-rich isotopes 58 Ti, 61 V, 63 Cr, 66 Mn, 69 Fe, 71 Co and neighbouring isotopes that have been identified as projectile fragments from reactions between a 500 MeV/u 86 Kr beam and a beryllium target. The isotope identification was performed with the zero-degree magnetic spectrometer FRS at GSI, using in addition time-of-flight and energy-loss mesurements. The experimental production cross-sections for the new nuclides and neighbouring isotopes are compared with an empirical parameterization. The resulting prospects for reaching even more neutron-rich isotopes, such as the doubly-magic nuclide 78 Ni, are discussed. (orig.)

  2. A dedicated AMS setup for medium mass isotopes at the Cologne FN tandem accelerator

    Science.gov (United States)

    Schiffer, M.; Altenkirch, R.; Feuerstein, C.; Müller-Gatermann, C.; Hackenberg, G.; Herb, S.; Bhandari, P.; Heinze, S.; Stolz, A.; Dewald, A.

    2017-09-01

    AMS measurements of medium mass isotopes, e.g. of 53Mn and 60Fe, are gaining interest in various fields of operation, especially geoscience. Therefore a dedicated AMS setup has been built at the Cologne 10 MV FN tandem accelerator. This setup is designed to obtain a sufficient suppression of the stable isobars at energies around 100 MeV. In this contribution we report on the actual status of the new setup and the first in-beam tests of its individual components. The isobar suppression is done with (dE/dx) techniques using combinations of energy degrader foils with an electrostatic analyzer (ESA) and a time of flight (ToF) system, as well as a (dE/dx),E gas ionization detector. Furthermore, the upgraded ion source and its negative ion yield measurement for MnO- are presented.

  3. Deexcitation of nuclei formed near the instability temperature

    International Nuclear Information System (INIS)

    Rivet, M.F.; Borderie, B.; Gauvin, H.; Gardes, D.; Cabot, C.; Hanappe, F.; Peter, J.

    1986-01-01

    Fusion-like reactions induced on medium mass targets by 27 MeV per nucleon argon projectiles were studied. The properties of evaporation residues and binary fission fragments, both cold remnants of fusion nuclei, show that highly excited nuclei were produced, near the temperature of instability of nuclear matter. Fission-evaporation competition in the deexcitation of these nuclei is reflected in the ratio of fission and residue cross sections, which provides a way of studying the role of prefission evaporation and fission barriers in the deexcitation process

  4. Translationally invariant treatment of pair correlations in nuclei: I. Spin and isospin dependent correlations

    Energy Technology Data Exchange (ETDEWEB)

    Guardiola, R. [Valencia Univ., Burjassot (Spain). Dept. de Fisica Atomica, Molecular y Nucl.; Moliner, P.I. [Valencia Univ., Burjassot (Spain). Dept. de Fisica Atomica, Molecular y Nucl.; Navarro, J. [IFIC (Centre Mixt CSIC -Universitat de Valencia), Avda. Dr. Moliner 50, E-46100 Burjassot (Spain); Bishop, R.F. [Department of Physics, UMIST, P.O. Box 88, Manchester M60 1QD (United Kingdom); Puente, A. [Department of Physics, UMIST, P.O. Box 88, Manchester M60 1QD (United Kingdom); Walet, N.R. [Department of Physics, UMIST, P.O. Box 88, Manchester M60 1QD (United Kingdom)

    1996-11-11

    We study the extension of our translationally invariant treatment of few-body nuclear systems to heavier nuclei. At the same time we also introduce state-dependent correlation operators. Our techniques are tailored to those nuclei that can be dealt with in LS coupling, which includes all nuclei up to the shell closure at A=40. We study mainly p-shell nuclei in this paper. A detailed comparison with other microscopic many-body approaches is made, using a variety of schematic nuclear interactions. It is shown that our methodology produces very good energies, and presumably also wave functions, for medium mass nuclei. (orig.).

  5. Multinucleon-Transfer Reactions as a Gateway to Neutron-Rich Actinides and Nuclei near the N=82 and Z=50 Shell Closures

    OpenAIRE

    Vogt, Andreas Günter Heinz

    2017-01-01

    In the present work, reaction products in the 136Xe+238U multinucleon-transfer reaction at 1 GeV were investigated employing the high-resolution position-sensitive gamma-ray tracking array AGATA coupled to the large-solid-angle mass spectrometer PRISMA at the Laboratori Nazionali di Legnaro (INFN, Italy). Beam-like reaction products were identified and selected by the PRISMA spectrometer. Recoils and fission fragments were tagged by DANTE micro-channel plate detectors installed within the sca...

  6. β-decay half-lives of neutron-rich nuclei around 158Nd, relevant to the formation of the A≈165 rare-earth element peak

    Directory of Open Access Journals (Sweden)

    Wu J.

    2016-01-01

    Full Text Available A β-decay spectroscopy experiment around 158Nd was performed at RI Beam Factory (RIBF, RIKEN Nishina Center, in order to understand the production mechanism of the A≈165 rare-earth element (REE peak in the r-process mass abundance pattern. In this experiment, 53 half-lives are measured including 34 new results, which could be employed in a fully dynamic r-process network calculation.

  7. Identification of more than a 100 new isotopes from 238U projectile fission and beams of neutron-rich nuclei at BRENDA

    International Nuclear Information System (INIS)

    Bernas, M.; Donzaud, C.; Dessagne, Ph.

    1996-01-01

    Projectile fission of 238 U was investigated at a bombarding energy of 750 A MeV using Pb and Be targets. The fully stripped forward emitted fragments from Ti to Cs were analyzed with the Fragment Separator (FRS) and unambiguously identified by their energy-loss and time-of-flight. The magnetic selection of the largest momenta acted as a trigger of the low-energy fission component. More than a hundred new nuclear species were identified including the 78 Ni, for which a cross-section of 300 pb was measured. (author)

  8. 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

  9. In-beam gamma-ray spectroscopy of the neutron-rich nitrogen isotopes N19-22

    Czech Academy of Sciences Publication Activity Database

    Sohler, D.; Stanoiu, M.; Dombrádi, Zs.; Azaiez, F.; Brown, BA.; Saint Laurent, M. G.; Sorlin, O.; Penionzhkevich, Y. E.; Achouri, N. L.; Angelique, J. C.; Belleguic, M.; Borcea, C.; Bourgeois, C.; Daugas, J. M.; de Oliveira Santos, F.; Dlouhý, Zdeněk; Donzaud, C.; Duprat, J.; Elekes, Z.; Grévy, S.; Guilemaud-Mueller, D.; Ibrahim, F.; Leenhardt, S.; Lewitowicz, M.; Lopez-Jimenez, M. J.; Lukyanov, S. M.; Mittig, W.; Mrázek, Jaromír; Negoita, F.; Podolyák, Zs.; Porquet, M. G.; Pougheon, F.; Roussel-Chomaz, P.; Savajols, H.; Sletten, G.; Sobolev, Y.; Stodel, C.; Timár, J.

    2008-01-01

    Roč. 77, č. 4 (2008), 044303/1-044303/8 ISSN 0556-2813 Institutional research plan: CEZ:AV0Z10480505 Keywords : ENERGY-LEVELS * DRIP-LINE * LIGHT-NUCLEI Subject RIV: BE - Theoretical Physics Impact factor: 3.124, year: 2008

  10. Shell effects and nucleosynthesis of heavy nuclei

    International Nuclear Information System (INIS)

    Farhan, A.R.; Sharma, M.M.

    2005-01-01

    The nuclear shell effects across the magic numbers N = 50, 82 and 126 near the r-process path are crucial to understanding the nucleosynthesis of heavy nuclei. Since nuclei near the r-process path are extremely neutron rich and are not accessible in the laboratory, the current understanding of the nuclear abundances is based much upon extrapolations of various mass formulae. In this talk, we will discuss as to how the shell effects evolve in going from the stability line to the r-process path and towards drip line in the heavy mass region. Within the framework of to the relativistic Hartree-Bogoliubov (RHB) theory with the vector self-coupling of omega meson, it will be shown that the shell effects across N = 82 show a significant decline in going from the r-process path to the drip line, whereas those at N = 126 remain resilient to the change in isospin in going from the r-process path to the neutron drip line. This behaviour of the microscopic RHB calculations is consistent with the recent r-process calculations suggesting that a shell quenching at N = 82 would be useful, however, a quenching is not necessary for reproducing r-process abundances near the peak at A ∼ 190. We will also show that due to an onset of deformation for nuclei above N = 126, an additional stability in some nuclei beyond the neutron drip line is provided. Consequently, this would contribute to r-process nuclear abundances in the third peak. A comparative analysis of shell effects with the microscopic RMF theory and with the macroscopic-microscopic mass formulae shows that the microscopic RMF theory possesses the potential of describing nuclear abundances in the peaks about A ∼ 130 and A ∼ 190. (author)

  11. Study of the nuclear structure far from stability: Coulomb excitation of neutron-rich Rb isotopes around N=60; Production of nuclear spin polarized beams using the tilted foils technique

    International Nuclear Information System (INIS)

    Sotty, C.

    2013-01-01

    The underlying structure in the region A ∼ 100, N ∼ 60 has been under intensive and extensive investigation, mainly by β-decay and γ-ray spectroscopy from fission processes. Around N ∼ 60, by adding just few neutrons, protons a rapid shape change occurs from spherical-like to well deformed g.s. shape. Shape coexistence has been observed in the Sr and Zr nuclei, and is expected to take place in the whole region. The mechanisms involved in the appearance of the deformation is not well understood. The interplay between down-sloping and up-sloping neutron Nilsson orbital is evoked as one of the main reasons for the sudden shape change. However, a clear identification of the active proton and neutron orbitals was still on-going. For that purpose, the neutron rich 93;95;97;99 Rb isotopes have been studied by Coulomb excitation at CERN (ISOLDE) using the REX-ISOLDE post-accelerator and the MINIBALL setup. The completely unknown structures of 97;99 Rb have been populated and observed. Prompt γ-ray coincidences of low-lying states have been observed and time-correlated in order to build level schemes. The associated transition strengths have been extracted with the GOSIA code. The observed matrix elements of the electromagnetic operator constituted new inputs of further theoretical calculations giving new insight on the involved orbitals. The sensitivity of such experiment can be increased using nuclear spin polarized radioactive ion beam. For that purpose the Tilted Foils Technique (TFT) of polarization has been investigated at CERN. This technique consists to spin polarize the ion beam, passing through thin foils tilted at an oblique angle with respect to the beam direction. The initially obtained atomic polarization is transferred to the nucleus by hyperfine interaction. This technique does not depend on the chemical nature of the element. Short lived nuclei can be polarized in-flight without any need to be stopped in a catcher. It opens up the possibility to

  12. New results from isochronous mass measurements of neutron-rich uranium fission fragments with the FRS-ESR-facility at GSI

    Energy Technology Data Exchange (ETDEWEB)

    Knoebel, R.; Litvinov, Yu.A.; Weick, H.; Bosch, F.; Boutin, D.; Dimopoulou, C.; Dolinskii, A.; Franczak, B.; Franzke, B.; Kozhuharov, C.; Kurcewicz, J.; Litvinov, S.A.; Matos, M.; Mazzocco, M.; Muenzenberg, G.; Nociforo, C.; Nolden, F.; Stadlmann, J.; Steck, M.; Winkler, M. [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); Diwisch, M. [Justus-Liebig-Universitaet Giessen, II. Physikalisches Institut, Giessen (Germany); Geissel, H.; Plass, W.R.; Scheidenberger, C.; Chen, L. [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); Justus-Liebig-Universitaet Giessen, II. Physikalisches Institut, Giessen (Germany); Patyk, Z. [National Centre for Nuclear Research - NCBJ Swierk, Warszawa (Poland); Sun, B. [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); Beihang University, School of Physics and Nuclear Energy Engineering, Beijing (China); Hausmann, M. [Michigan State University, East Lansing, MI (United States); Nakajima, S.; Suzuki, T.; Yamaguchi, T. [Saitama University, Department of Physics, Saitama (Japan); Ohtsubo, T. [Niigata University, Department of Physics, Niigata (Japan); Ozawa, A. [University of Tsukuba, Institute of Physics, Ibaraki (Japan); Walker, P.M. [University of Surrey, Department of Physics, Guildford (United Kingdom)

    2016-05-15

    Masses of uranium fission fragments have been measured with the FRagment Separator (FRS) combined with the Experimental Storage Ring (ESR) at GSI. A 410-415 MeV/u {sup 238}U projectile beam was fast extracted from the synchrotron SIS-18 with an average intensity of 10{sup 9}/spill. The projectiles were focused on a 1g/cm{sup 2} beryllium target at the entrance of the FRS to create neutron-rich isotopes via abrasion-fission. The fission fragments were spatially separated with the FRS and injected into the isochronous storage ring ESR for fast mass measurements without applying cooling. The Isochronous Mass Spectrometry (IMS) was performed under two different experimental conditions, with and without B ρ-tagging at the high-resolution dispersive central focal plane of the FRS. The evaluation has been done for the combined data sets from both experiments with a new method of data analysis. The use of a correlation matrix has provided experimental mass values for 23 different neutron-rich isotopes for the first time and 6 masses with improved values. The new masses were obtained for nuclides in the element range from Se to Ce. The applied analysis has given access even to rare isotopes detected with an intensity of a few atoms per week. The novel data analysis and systematic error determination are described and the results are compared with extrapolations of experimental values and theoretical models. (orig.)

  13. Electron scattering and reactions from exotic nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Karataglidis, S. [University of Johannesburg, Department of Physics, Auckland Park (South Africa); University of Melbourne, School of Physics, Victoria (Australia)

    2017-04-15

    The SCRIT and FAIR/ELISe experiments are the first to attempt to measure directly electron scattering form factors from nuclei far from stability. This will give direct information for the (one-body) charge densities of those systems, about which there is little information available. The SCRIT experiment will be taking data for medium-mass exotic nuclei, while the electron-ion collider at ELISe, when constructed, will be able to measure form factors for a wide range of exotic nuclei, as available from the radioactive ion beams produced by the FAIR experiment. Other facilities are now being proposed, which will also consider electron scattering from exotic nuclei at higher energies, to study short-range correlations in exclusive reactions. This review will consider all available information concerning the current status (largely theoretical) of electron scattering from exotic nuclei and, where possible, complement such information with equivalent information concerning the neutron densities of those exotic systems, as obtained from intermediate energy proton scattering. The issue of long- and short-range correlations will be discussed, and whether extending such studies to the exotic sector will elicit new information. (orig.)

  14. Exploring the changing of shell structure of nuclei at N=50

    International Nuclear Information System (INIS)

    Here it is reported an experimental study of the excited structures of the neutron-rich N=50 and 51 isotones. New experimental information has been obtained on a wide range of nuclei close to the N=50 shell closure by means of multi-nucleon transfer and deep-inelastic collisions. The reaction mechanism allows the population of medium and high-spin yrast states. The systematic of the N=51 single-neutron states, extended down to the Z=34, can be used to test the predictions of the shell evolution based on the effects of the tensor interactions as well as of the different effective interactions

  15. Beta-decay spectroscopy of r-process nuclei around N = 126

    Directory of Open Access Journals (Sweden)

    Hirayama Y.

    2016-01-01

    Full Text Available KEK Isotope Separation System (KISS has been developed at RIKEN to study the β-decay properties of neutron-rich isotopes with neutron numbers around N = 126 to understand the astrophysical site of r-process. These nuclei will be produced by multi-nucleon transfer reactions in neutron-rich heavy ion collisions between 136Xe beam and 198Pt target. The KISS consists of an argon gas cell combined with a laser resonance ionization technique for atomic number selection, of an ISOL mass-separation system and of a detector system for the β-decay spectroscopy of nuclei around N = 126. The argon gas cell of KISS is a key component for thermalizing (stopping and neutralizing and accumulating the unstable nuclei, and selectively ionizing them by using laser. We have performed off-and on-line experiments to study the basic properties of the gas cell as well as KISS. We successfully extracted the laser-ionized stable 198Pt atoms from the KISS at the commissioning on-line experiments. We furthermore extracted laser-ionized unstable 199Pt atoms and confirmed that the measured half-life was in good agreement with the reported value. Now KISS is ready for lifetime measurements of Pt, Ir, and Os isotopes around N = 126.

  16. G-parity violation of weak nucleon current and in-medium mass renormalization of nucleons detected through the beta decays of spin aligned sup 1 sup 2 B and sup 1 sup 2 N

    CERN Document Server

    Minamisono, K; Sumikama, T; Nagatomo, T; Matsuta, K; Minamisono, T; Fukuda, M; Koshigiri, K; Morita, M

    2000-01-01

    The beta-ray angular distributions from purely spin aligned sup 1 sup 2 B and sup 1 sup 2 N were precisely measured to determine a new limit of the G-parity irregular induced tensor form factor in weak nucleon axial vector currents and to study the in-medium mass renormalization of nucleons through the axial charge. Since the major systematic error in the previous result which originated from the intensity fluctuation of the incident beam used for the production of the nuclei was removed in the present measurement, the more reliable result was obtained: 0.01 <= 2M f sub T /f sub A <= 0.34 (90 % CL). The result is consistent with the theoretical prediction in the framework of which induced tensor form factor is proportional to the mass difference between the up and down quarks. We also determined the axial charge of the weak nucleon current to be y = 4.66 +- 0.12, which may disclose an in-medium mass reduction of the decaying nucleon of 11 +- 4 %.

  17. Colliding nuclei

    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.)

  18. Evolution of the pi g sub 9 sub / sub 2 x nu h sub 1 sub 1 sub / sub 2 configuration in the neutron-rich sup 1 sup 1 sup 0 sup , sup 1 sup 1 sup 2 sub 4 sub 5 Rh and sup 1 sup 1 sup 4 sup , sup 1 sup 1 sup 6 sub 4 sub 7 Ag isotopes

    CERN Document Server

    Porquet, M G; Deloncle, I; Venkova, T; Astier, A; Buforn, N; Meyer, M; Prevost, A; Redon, N; Stezowski, O; Donadille, L; Dorvaux, O; Gall, B J P; Schulz, N; Lalkovski, S; Lucas, R; Minkova, A

    2003-01-01

    The sup 1 sup 1 sup 0 sup , sup 1 sup 1 sup 2 Rh and sup 1 sup 1 sup 4 sup , sup 1 sup 1 sup 6 Ag nuclei have been produced as fission fragments in the fusion reaction sup 1 sup 8 O+ sup 2 sup 0 sup 8 Pb at 85 MeV. Their level schemes have been built from gamma-rays detected using the Euroball IV array. High-spin states of these neutron-rich nuclei have been identified for the first time. The yrast structures consist of rotational bands in which the odd proton occupies the pi g sub 9 sub / sub 2 sub-shell and the odd neutron the nu h sub 1 sub 1 sub / sub 2 sub-shell. The evolution of the pi g sub 9 sub / sub 2 x nu h sub 1 sub 1 sub / sub 2 band structure is analyzed as a function of the neutron number.

  19. 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.)

  20. Nuclei at extreme conditions. A relativistic study

    Energy Technology Data Exchange (ETDEWEB)

    Afanasjev, Anatoli [Mississippi State Univ., Mississippi State, MS (United States)

    2014-11-14

    The major goals of the current project were further development of covariant density functional theory (CDFT), better understanding of its features, its application to different nuclear structure and nuclear astrophysics phenomena and training of graduate and undergraduate students. The investigations have proceeded in a number of directions which are discussed in detail in the part “Accomplishments” of this report. We have studied the role of isovector and isoscalar proton-neutron pairings in rotating nuclei; based on available experimental data it was concluded that there are no evidences for the existence of isoscalar proton-neutron pairing. Generalized theoretical approach has been developed for pycnonuclear reaction rates in the crust of neutron stars and interior of white dwarfs. Using this approach, extensive database for considerable number of pycnonuclear reactions involving stable and neutron-rich light nuclei has been created; it can be used in future for the study of various nuclear burning phenomena in different environments. Time-odd mean fields and their manifestations in terminating states, non-rotating and rotating nuclei have been studied in the framework of covariant density functional theory. Contrary to non-relativistic density functional theories these fields, which are important for a proper description of nuclear systems with broken time-reversal symmetry, are uniquely defined in the CDFT framework. Hyperdeformed nuclear shapes (with semi-axis ratio 2.5:1 and larger) have been studied in the Z = 40-58 part of nuclear chart. We strongly believe that such shapes could be studied experimentally in the future with full scale GRETA detector.

  1. Mass Measurement of Very Short Half-Lived Nuclei

    CERN Multimedia

    Duma, M; Iacob, V E; Thibault, C

    2002-01-01

    The MISTRAL (Mass measurements at ISolde with a Transmission RAdiofrequency spectrometer on-Line) experiment exploits a rapid measurement technique to make accurate mass determinations of very short-lived nuclei. The physics goals are to elucidate new nuclear structure effects and constrain nuclear mass models in regions of interest to nuclear astrophysics.\\\\ \\\\The spectrometer, installed in May 97, performed as promised in the proposal with mass resolution exceeding 100,000. In its first experiment in July 1998, neutron-rich Na isotopes having half-lives as short as 31 ms were measured. A second experiment in November 1998 enabled us to improve the measurement precision of the isotopes $^{26-30}$Na to about 20 keV. The measurement program continues as experiment IS 373.

  2. Observational Study of Morphological Changes in Medium-mass Evolved Stars

    Science.gov (United States)

    Chong, Sze-Ning

    2014-02-01

    Medium-mass (or intermediate-mass) stars refer to main sequence stars with masses ranging from 0.4 to 8 solar masses. These stars are believed to finally evolve into the central stars of planetary nebulae (PNe) and white dwarfs. One of the fascinating aspects of PNe is their diverse morphology. To understand the mechanisms of the morphological changes from spherical circumstellar envelopes (CSEs) of asymptotic giant branch (AGB) stars to those forming highly diversified PNe, it is necessary to investigate the true three-dimensional (3D) morphology of PNe from two-dimensional images, and the short transition phase in-between the two phases should also be explored. "Water Fountain" (WF) sources belong to transition phase objects; they are AGB or post-AGB stars with collimated jets traced by high velocity water maser emissions in their CSEs. This thesis comprises of four chapters. The results can be divided into two major parts. Chapter 1 is the introduction on the related fields with brief reviews of previous observational studies on PNe and the rapidly evolving transition phase objects. Basic theories necessary for understanding the next chapters were also described, including those explaining the commonly observed Hα emission in PNe, the formation of multipolar PNe, the maser emission and the role of shock in circumstellar materials. The first major part of the results, about the morphological classification of multipolar PNe, is presented in Chapter 2. At the beginning of the chapter, the problems on the previous classification methods were pointed out. Then a three-lobed model was introduced. By changing the combination of the orientations of the three pairs of lobes, simulations using the model produced statistical results in classification and quantified the errors of misidentification. Assuming that all PNe observed have the true structure of three lobes, due to projection effect, only 49% of them would be correctly classified. 46% and 5% of them would be

  3. A systematic study of band structure and electromagnetic properties of neutron rich odd mass Eu isotopes in the projected shell model framework

    Energy Technology Data Exchange (ETDEWEB)

    Pandit, Rakesh K.; Devi, Rani [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)

    2017-10-15

    The positive and negative parity rotational band structure of the neutron rich odd mass Eu isotopes with neutron numbers ranging from 90 to 96 are investigated up to the high angular momentum. In the theoretical analysis of energy spectra, transition energies and electromagnetic transition probabilities we employ the projected shell model. The calculations successfully describe the formation of the ground and excited band structures from the single particle and multi quasiparticle configurations. Calculated excitation energy spectra, transition energies, exact quantum mechanically calculated B(E2) and B(M1) transition probabilities are compared with experimental data wherever available and a reasonably good agreement is obtained with the observed data. The change in deformation in the ground state band with the increase in angular momentum and the increase in neutron number has also been established. (orig.)

  4. Mean free paths and in-medium scattering cross sections of energetic nucleons in neutron-rich nucleonic matter within the relativistic impulse approximation

    International Nuclear Information System (INIS)

    Jiang Weizhou; Li Baoan; Chen Liewen

    2007-01-01

    The mean free paths and in-medium scattering cross sections of energetic nucleons in neutron-rich nucleonic matter are investigated using the nucleon optical potential obtained within the relativistic impulse approximation with the empirical nucleon-nucleon scattering amplitudes and the nuclear densities obtained in the relativistic mean-field model. It is found that the isospin-splitting of nucleon mean free paths, sensitive to the imaginary part of the symmetry potential, changes its sign at certain high kinetic energy. The in-medium nucleon-nucleon cross sections are analytically and numerically demonstrated to be essentially independent of the isospin asymmetry of the medium and increase linearly with density in the high-energy region where the relativistic impulse approximation is applicable

  5. Shape coexistence in the N=19 neutron-rich nucleus 31Mg explored by β–γ spectroscopy of spin-polarized 31Na

    Directory of Open Access Journals (Sweden)

    H. Nishibata

    2017-04-01

    Full Text Available The structure of excited states in the neutron-rich nucleus 31Mg, which is in the region of the “island of inversion” associated with the neutron magic number N=20, is studied by β–γ spectroscopy of spin-polarized 31Na. Among the 31Mg levels below the one neutron separation energy of 2.3 MeV, the spin values of all five positive-parity levels are unambiguously determined by observing the anisotropic β decay. Two rotational bands with Kπ=1/2+ and 1/2− are proposed based on the spins and energies of the levels. Comparison on a level-by-level basis is performed between the experimental results and theoretical calculations by the antisymmetrized molecular dynamics (AMD plus generator coordinate method (GCM. It is found that various nuclear structures coexist in the low excitation energy region in 31Mg.

  6. Negative-parity intruder states of the neutron-rich N=20, Z=14-16 isotones: a 1{Dirac_h}{omega} shell model description

    Energy Technology Data Exchange (ETDEWEB)

    Bouhelal, M. [Universite de Strasbourg, IPHC, CNRS/IN2P3, Strasbourg (France); Universite de Batna, Departement de Physique, Faculte des Sciences, Batna (Algeria); Haas, F.; Caurier, E.; Nowacki, F. [Universite de Strasbourg, IPHC, CNRS/IN2P3, Strasbourg (France); Bouldjedri, A. [Universite de Batna, Departement de Physique, Faculte des Sciences, Batna (Algeria)

    2009-12-15

    In order to get a consistent shell model description of the negative-parity states throughout the sd shell a new interaction (PSDPFB) has been developed. It was derived in the full p-sd-pf model space and is built on existing interactions for the major shells with adjustments of the cross-shell monopoles. The calculated energy spectra for these 1{Dirac_h}{omega} intruder states are compared to experiment for the N=20 neutron-rich isotones {sup 34}Si, {sup 35}P and {sup 36}S. A systematics for the multiplet configuration {nu}(d{sub 3/2}{sup -1}f{sub 7/2}{sup 1}) in even-even isotones from {sup 34}Si to {sup 40}Ca is also presented. (orig.)

  7. Spectroscopic Quadrupole Moments in {96,98}Sr: Evidence for Shape Coexistence in Neutron-Rich Strontium Isotopes at N=60.

    Science.gov (United States)

    Clément, E; Zielińska, M; Görgen, A; Korten, W; Péru, S; Libert, J; Goutte, H; Hilaire, S; Bastin, B; Bauer, C; Blazhev, A; Bree, N; Bruyneel, B; Butler, P A; Butterworth, J; Delahaye, P; Dijon, A; Doherty, D T; Ekström, A; Fitzpatrick, C; Fransen, C; Georgiev, G; Gernhäuser, R; Hess, H; Iwanicki, J; Jenkins, D G; Larsen, A C; Ljungvall, J; Lutter, R; Marley, P; Moschner, K; Napiorkowski, P J; Pakarinen, J; Petts, A; Reiter, P; Renstrøm, T; Seidlitz, M; Siebeck, B; Siem, S; Sotty, C; Srebrny, J; Stefanescu, I; Tveten, G M; Van de Walle, J; Vermeulen, M; Voulot, D; Warr, N; Wenander, F; Wiens, A; De Witte, H; Wrzosek-Lipska, K

    2016-01-15

    Neutron-rich {96,98}Sr isotopes have been investigated by safe Coulomb excitation of radioactive beams at the REX-ISOLDE facility. Reduced transition probabilities and spectroscopic quadrupole moments have been extracted from the differential Coulomb excitation cross sections. These results allow, for the first time, the drawing of definite conclusions about the shape coexistence of highly deformed prolate and spherical configurations. In particular, a very small mixing between the coexisting states is observed, contrary to other mass regions where strong mixing is present. Experimental results have been compared to beyond-mean-field calculations using the Gogny D1S interaction in a five-dimensional collective Hamiltonian formalism, which reproduce the shape change at N=60.

  8. Primordial nuclei

    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

  9. Spectroscopical study of the yrast and yrare structure in far-from-stability nuclei; Etude spectroscopique de la structure yrast et yrare de noyaux loin de la stabilite

    Energy Technology Data Exchange (ETDEWEB)

    Hoellinger Fabien [Institut de Recherches Subatomiques, 23, Rue du Loess, BP 28, 67037 Strasbourg Cedex 2 (France)]|[Universite Louis Pasteur, 67 - Strasbourg (France)

    1999-01-13

    The nuclear structure study of neutron-rich nuclei was realized with the EUROGAM II array in two different experiments. The first study consisted in the analysis of the product of spontaneous fission of {sup 248}Cm. Three neutron-rich cerium isotopes {sup 147,149,151}Ce were analyzed. A level scheme for {sup 151}Ce is presented for the first time. The yrast structure of the three nuclei does not show alternative parity bands as expected in this region of octupole deformations. We studied the rotational structure of the bands and this leads to suggest Nilsson configurations to some of them. The aim of this second experiment was the study of the nuclei {sup 99}Mo, {sup 101}Tc, {sup 103}Ru. The three nuclei are situated on the neutron-rich side of the nuclear chart and are produced as fission fragments of a heavy-ion induced reaction. Some bands are extended to higher spins and some new bands are observed. The structure of the rotational bands is interpreted by means of the Hartree-Fock-Bogolyubov model. A last experiment intended to study the structure of the proton-rich nucleus {sup 223}Pa has been achieved with the JURO+RITU array located at Jyvaeskylae (Finland). In this proton-rich actinide region, the nuclei develop octupole features around Z{approx_equal}88, N{approx_equal}132. The analysis of this experiment leads to the first assignment of gamma transitions to the {sup 223}Pa. (author) 91 refs., 78 figs., 16 tabs.

  10. Recent activities for β-decay half-lives and β-delayed neutron emission of very neutron-rich isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Dillmann, Iris [TRIUMF, Vancouver BC, V6T 2A3, Canada and GSI Helmholtzzentrum für Schwerionenforschung GmbH, D-64291 Darmstadt (Germany); Abriola, Daniel [Laboratorio Tandar, Comisión Nacional de Energía Atómica, B1650KINA, San Martín, Buenos Aires (Argentina); Singh, Balraj [Department of Physics and Astronomy, McMaster University, Hamilton ON, L8S 4M1 (Canada)

    2014-05-02

    Beta-delayed neutron (βn) emitters play an important, two-fold role in the stellar nucleosynthesis of heavy elements in the 'rapid neutron-capture process' (r process). On one hand they lead to a detour of the material β-decaying back to stability. On the other hand, the released neutrons increase the neutron-to-seed ratio, and are re-captured during the freeze-out phase and thus influence the final solar r-abundance curve. A large fraction of the isotopes inside the r-process reaction path are not yet experimentally accessible and are located in the (experimental) 'Terra Incognita'. With the next generation of fragmentation and ISOL facilities presently being built or already in operation, one of the main motivation of all projects is the investigation of these very neutron-rich isotopes. A short overview of one of the planned programs to measure βn-emitters at the limits of the presently know isotopes, the BRIKEN campaign (Beta delayed neutron emission measurements at RIKEN) will be given. Presently, about 600 β-delayed one-neutron emitters are accessible, but only for a third of them experimental data are available. Reaching more neutron-rich isotopes means also that multiple neutron-emission becomes the dominant decay mechanism. About 460 β-delayed two-, three-or four-neutron emitters are identified up to now but for only 30 of them experimental data about the neutron branching ratios are available, most of them in the light mass region below A=30. The International Atomic and Energy Agency (IAEA) has identified the urgency and picked up this topic recently in a 'Coordinated Research Project' on a 'Reference Database for Beta-Delayed Neutron Emission Data'. This project will review, compile, and evaluate the existing data for neutron-branching ratios and half-lives of β-delayed neutron emitters and help to ensure a reliable database for the future discoveries of new isotopes and help to constrain astrophysical and

  11. What does the ρ-meson do? In-medium mass shift scenarios versus hadronic model calculations

    International Nuclear Information System (INIS)

    Ruppert, J.; Renk, T.

    2007-01-01

    The NA60 experiment has studied low-mass muon pair production in In-In collisions at 158 A GeV with unprecedented precision. With these results there is hope that the in-medium modifications of the vector meson spectral function can be constrained more thoroughly than before. We investigate in particular what can be learned about collisional broadening by a hot and dense medium and what constraints the experimental results put on in-medium mass shift scenarios. The data show a clear indication of considerable in-medium broadening effects but disfavor mass shift scenarios where the ρ-meson mass scales with the square root of the chiral condensate. Scaling scenarios which predict at finite density a dropping of the ρ-meson mass that is stronger than that of the quark condensate are clearly ruled out since they are also accompanied by a sharpening of the spectral function. (orig.)

  12. Study of single particle properties of neutron-rich Na isotopes on the "shore of the island of inversion" by means of neutron-transfer reactions

    CERN Multimedia

    Reiter, P; Blazhev, A A; Riisager, K; Bastin, B; Tengborn, E A; Kruecken, R; Voulot, D; Jeppesen, H B; Hadinia, B; Gernhaeuser, R A; Fynbo, H O U; Georgiev, G P; Habs, D; Fraile prieto, L M; Chapman, R; Nilsson, T; Diriken, J V J; Jenkins, D G; Kroell, T; Leske, J; Huyse, M L; Patronis, N

    We aim at the investigation of single particle properties of neutron-rich Na isotopes around the "shore of the island of inversion". As first experiment of this programme, we propose to study excited states in the isotope $^{29}$Na by a one-neutron transfer reaction with a $^{28}$Na 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 the T-REX array of segmented Si detectors. The main physics aims are to extract from the relative spectroscopic factors information on the configurations contributing to the wave functions of the populated states and, secondly, to identify and characterize negative parity states whose excitation energies reflect directly the N= 28 gap in this region. The results will be compared to recent shell model calculations involving new residual interactions. This will shed new light on the evolution of single particle structure and help to understand the underlying physics relevant for the f...

  13. Difference in proton radii of mirror nuclei as a possible surrogate for the neutron skin

    Science.gov (United States)

    Yang, Junjie; Piekarewicz, J.

    2018-01-01

    It has recently been suggested that differences in the charge radii of mirror nuclei are proportional to the neutron-skin thickness of neutron-rich nuclei and to the slope of the symmetry energy L [Brown, Phys. Rev. Lett. 102, 122502 (2009), 10.1103/PhysRevLett.102.122502]. The determination of the neutron skin has important implications for nuclear physics and astrophysics. Although the use of electroweak probes provides a largely model-independent determination of the neutron skin, the experimental challenges are enormous. Thus, the possibility that differences in the charge radii of mirror nuclei may be used as a surrogate for the neutron skin is a welcome alternative. To test the validity of this assumption we perform calculations based on a set of relativistic energy density functionals that span a wide region of values of L . Our results confirm that the difference in charge radii between various neutron-deficient nickel isotopes and their corresponding mirror nuclei is indeed strongly correlated to both the neutron-skin thickness and L . Moreover, given that various neutron-star properties are also sensitive to L , a data-to-data relation emerges between the difference in charge radii of mirror nuclei and the radius of low-mass neutron stars.

  14. Beta-delayed fission probabilities of transfermium nuclei, involved in the r-process

    International Nuclear Information System (INIS)

    Panov, I; Lutostansky, Yu; Thielemann, F-K

    2016-01-01

    For the nucleosynthesis of heavy and superheavy nuclei fission becomes very important when the r-process runs in a very high neutron density environment. In part, fission is responsible for the formation of heavy nuclei due to the inclusion of fission products as new seed nuclei (fission cycling). More than that, beta-delayed fission, along with spontaneous fission, is responsible in the late stages of the r-process for the suppression of superheavy element yields.For beta-delayed fission probability calculations a model description of the beta-strength- functions is required. Extended theoretical predictions for astro-physical applications were provided long ago, and new predictions also for superheavy nuclei with uptodate nuclear input are needed. For the further extension of data to heavier transactinides the models of strength- functions should be modified, taking into account more complicated level schemes. In our present calculations the strength-function model is based on the quasi-particle approximation of Finite Fermi Systems Theory.The probabilities of beta-delayed fission and beta-delayed neutron emission are calculated for some transfermium neutron-rich nuclei, and the influence of beta-delayed fission upon superheavy element formation is discussed. (paper)

  15. Low-lying dipole response in stable and unstable nuclei

    International Nuclear Information System (INIS)

    Brenna, M; Colò, G; Bortignon, P F; Pozzi, G; Roca-Maza, X; Mizuyama, K

    2013-01-01

    The presence of some low-lying (pygmy) strength in the dipole spectrum, at excitation energy well below the isovector giant dipole energy, has been confirmed in several nuclei. The microscopic structure and the nature of these states, in particular the possible collective nature and the isospin character, are currently under strong debate. In addition, a relation with the isovector properties of the equation of state of nuclear matter, such as the symmetry energy or its slope, has been proposed. We present a detailed analysis of Skyrme Hartree–Fock plus random phase approximation (RPA) predictions for both the isoscalar and isovector dipole responses, of different neutron-rich nuclei ( 68 Ni, 132 Sn and 208 Pb). All of them show a low-energy peak that increases in magnitude with increasing values of the slope of the symmetry energy at saturation. Eventually, the collectivity associated with the RPA states contributing to this peak is more pronounced in the isoscalar than in the isovector channel. (paper)

  16. First one-line mass measurements at SHIPTRAP and mass determinations of neutron-rich Fr and Ra isotopes at ISOLTRAP

    Energy Technology Data Exchange (ETDEWEB)

    Rahaman, M.S.

    2005-02-16

    SHIPTRAP is an ion trap facility behind the velocity lter SHIP at GSI/Darmstadt. Its aim are precision studies of transuranium nuclides produced in a fusion reaction and separated by SHIP. The current set-up for high-precision mass measurements consists of three main functional parts: (i) a gas cell for stopping the energetic ions from SHIP, (ii) radiofrequency quadrupole structures to cool and to bunch the ions extracted from the gas cell, and (iii) a superconducting magnet with two cylindrical Penning traps at a eld strength of 7 T. In this work the Penning trap system has been installed and extensively characterized. The rst on-line mass measurements of short-lived nuclides were carried out and the masses of {sup 147}Er and {sup 148}Er could be experimentally determined for the rst time. Here a relative mass uncertainty of {delta}m/m of about 1 x 10{sup -6} was achieved. Furthermore the masses of heavy neutron-rich {sup 229-232}Ra and {sup 230}Fr isotopes have been determined with a relative mass uncertainty of about 1 x 10{sup -7} with the ISOLTRAP mass spectometer at ISOLDE/CERN. The isotope {sup 232}Ra is the heaviest unstable nuclide ever investigated with a Penning trap. Underlying nuclear structure effects of these nuclides far from {beta}-stability were studied by a comparison of the resulting two-neutron separation energies S{sub 2n} with those given by the theoretical Infinite Nuclear Mass model. (orig.)

  17. Analogies in the structure of exotic nuclei with N∼50 and N∼82

    International Nuclear Information System (INIS)

    Gorska, M.; Blazhev, A.; Boutachkov, P.

    2009-01-01

    Two main mechanisms are predicted to drive the possible shell evolution phenomena: the first is the so called monopole migration [1], which acts for both proton and neutron-rich nuclei, and the second, shell quenching, which is due to a softening of the potential shape that results from the presence of an excessive number of neutrons in very neutron-rich nuclei [2]. These mechanisms modify the known magic numbers as a consequence of shifting effective single-particle levels when going towards either the proton or the neutron drip lines. In medium-heavy nuclei the effort to establish shell evolution concentrates around the 1 00S n [3] and 1 32S n [4,5] doubly magic nuclei. The Sn isotopes form the longest isotopic chain in the nuclear chart accessible to current experimental study and thus provide a stringent testing ground for nuclear structure models. A remarkable similarity was found between the decay of 8 + isomers in 9 8C d 50 [6] and 1 30C d 82 [5], both of which have a pure g 9/2 -2 proton-hole configuration. However, the analogue of the known core excited isomer in 9 8C d [7] was not observed in 1 30C d, within experimental sensitivity, thus underlining the differences in the underlying neutron single-particle structure. The understanding of analogies in the structure of both regions of nuclei and the evolution of the N=82 shell gap below 1 32S n is of importance in predicting the path of the rapid-neutron capture process which partially drives the production of elements heavier than Fe in nature. A handful of additional information on these two regions of nuclei was obtained recently in spectroscopy studies within the Rare ISotopes INvestigation at GSI (RISING) project [8,9] including the rp-process waiting point nuclei. Selected results will be discussed and compared with large scale shell model calculations using various sets of the realistic residual two-body interaction.(author)

  18. Low-energy enhancement of nuclear γ strength and its impact on astrophysical reaction rates

    Directory of Open Access Journals (Sweden)

    Larsen A. C.

    2014-03-01

    Full Text Available An unexpected enhancement in the low-energy part of the γ-strength function for light and medium-mass nuclei has been discovered at the Oslo Cyclotron Laboratory. This enhancement could lead to an increase in the neutron-capture rates up to two orders of magnitude for very exotic, neutron-rich nuclei. However, it is still an open question whether this structure persists when approaching the neutron drip line.

  19. Synthesis and decay process of superheavy nuclei with Z=119-122 via hot-fusion reactions

    Energy Technology Data Exchange (ETDEWEB)

    Ghahramany, N.; Ansari, A. [Shiraz University, Department of Physics and Biruni Observatory, College of Science, Shiraz (Iran, Islamic Republic of)

    2016-09-15

    In this research article attempts have been made to calculate the superheavy-nuclei synthesis characteristics including, the potential energy parameters, fusion probability, fusion and evaporation residue (ER) cross sections as well as, decay properties of compound nucleus and the residue nuclei formation probability for elements with Z=119-122 by using the hot-fusion reactions. It is concluded that, although a selection of double magic projectiles such as {sup 48}Ca with high binding energy, simplifies the calculations significantly due to spherical symmetric shape of the projectile, resulting in high evaporation residue cross section, unfortunately, nuclei with Z > 98 do not exist in quantities sufficient for constructing targets for the hot-fusion reactions. Therefore, practically our selection is fusion reactions with titanium projectile because the mass production of target nuclei for experimental purposes is more feasible. Based upon our findings, it is necessary, for new superheavy-nuclei production with Z > 119, to use neutron-rich projectiles and target nuclei. Finally, the maximal evaporation residue cross sections for the synthesis of superheavy elements with Z=119-122 have been calculated and compared with the previously founded ones in the literature. (orig.)

  20. Synthesis and decay process of superheavy nuclei with Z=119-122 via hot-fusion reactions

    International Nuclear Information System (INIS)

    Ghahramany, N.; Ansari, A.

    2016-01-01

    In this research article attempts have been made to calculate the superheavy-nuclei synthesis characteristics including, the potential energy parameters, fusion probability, fusion and evaporation residue (ER) cross sections as well as, decay properties of compound nucleus and the residue nuclei formation probability for elements with Z=119-122 by using the hot-fusion reactions. It is concluded that, although a selection of double magic projectiles such as 48 Ca with high binding energy, simplifies the calculations significantly due to spherical symmetric shape of the projectile, resulting in high evaporation residue cross section, unfortunately, nuclei with Z > 98 do not exist in quantities sufficient for constructing targets for the hot-fusion reactions. Therefore, practically our selection is fusion reactions with titanium projectile because the mass production of target nuclei for experimental purposes is more feasible. Based upon our findings, it is necessary, for new superheavy-nuclei production with Z > 119, to use neutron-rich projectiles and target nuclei. Finally, the maximal evaporation residue cross sections for the synthesis of superheavy elements with Z=119-122 have been calculated and compared with the previously founded ones in the literature. (orig.)

  1. Shell-model method for Gamow-Teller transitions in heavy deformed odd-mass nuclei

    Science.gov (United States)

    Wang, Long-Jun; Sun, Yang; Ghorui, Surja K.

    2018-04-01

    A shell-model method for calculating Gamow-Teller (GT) transition rates in heavy deformed odd-mass nuclei is presented. The method is developed within the framework of the projected shell model. To implement the computation requirement when many multi-quasiparticle configurations are included in the basis, a numerical advancement based on the Pfaffian formula is introduced. With this new many-body technique, it becomes feasible to perform state-by-state calculations for the GT nuclear matrix elements of β -decay and electron-capture processes, including those at high excitation energies in heavy nuclei which are usually deformed. The first results, β- decays of the well-deformed A =153 neutron-rich nuclei, are shown as the example. The known log(f t ) data corresponding to the B (GT- ) decay rates of the ground state of 153Nd to the low-lying states of 153Pm are well described. It is further shown that the B (GT) distributions can have a strong dependence on the detailed microscopic structure of relevant states of both the parent and daughter nuclei.

  2. Exciting interdisciplinary physics quarks and gluons, atomic nuclei, relativity and cosmology, biological systems

    CERN Document Server

    2013-01-01

    Nuclear physics is an exciting, broadly faceted field. It spans a wide range of topics, reaching from nuclear structure physics to high-energy physics, astrophysics and medical physics (heavy ion tumor therapy).  New developments are presented in this volume and the status of research is reviewed. A major focus is put on nuclear structure physics, dealing with superheavy elements and with various forms of exotic nuclei: strange nuclei, very neutron rich nuclei, nuclei of antimatter. Also quantum electrodynamics of strong fields is addressed, which is linked to the occurrence of giant nuclear systems in, e.g., U+U collisions. At high energies nuclear physics joins with elementary particle physics. Various chapters address the theory of elementary matter at high densities and temperature, in particular the quark gluon plasma which is predicted by quantum chromodynamics (QCD) to occur in high-energy heavy ion collisions. In the field of nuclear astrophysics, the properties of neutron stars and quark stars are d...

  3. Continuum and symmetry-conserving effects in drip-line nuclei using finite-range forces

    International Nuclear Information System (INIS)

    Schunck, N.; Egido, J. L.

    2008-01-01

    We report the first calculations of nuclear properties near the drip lines using the spherical Hartree-Fock-Bogoliubov mean-field theory with a finite-range force supplemented by continuum and particle-number projection effects. Calculations were carried out in a basis made of the eigenstates of a Woods-Saxon potential computed in a box, thereby guaranteeing that continuum effects were properly taken into account. Projection of the self-consistent solutions on good particle number was carried out after variation, and an approximation of the variation after projection result was used. We give the position of the drip lines and examine neutron densities in neutron-rich nuclei. We discuss the sensitivity of nuclear observables upon continuum and particle-number restoration effects

  4. The time-of-flight isochronous (TOFI) spectrometer for direct mass measurements of exotic light nuclei

    International Nuclear Information System (INIS)

    Wouters, J.M.; Vieira, D.J.; Butler, G.W.; Wollnik, H.; Kraus, R.H. Jr.; Vaziri, K.

    1987-01-01

    A new type of time-of-flight recoil spectrometer designed to measure the masses of neutron-rich light nuclei has recently been completed at LAMPF. The spectrometer relies on an isochronous design that directly correlates an ion's time-of-flight through the spectrometer with its mass-to-charge ratio. Additional measurements of the ion's velocity and energy enable the charge state of the recoil to be uniquely defined and thus permit precision mass measurements given sufficient statistics. The performance of the spectrometer has been investigated in both-off line (using alpha sources) and on-line tests. The design resolution of ΔM/M=1/2000 (fwhm) has been achieved. Initial performance results of the spectrometer are described with emphasis placed on the techniques used to achieve the overall high mass resolution and large solid angle/momentum acceptance. (orig.)

  5. Nuclei and quantum worlds

    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

  6. Rotation-induced shape transitions in Dy nuclei

    International Nuclear Information System (INIS)

    Emling, H.; Grosse, E.; Kulessa, R.; Schwalm, D.; Wollersheim, H.J.

    1984-01-01

    Lifetimes of states with spins up to 30(h/2π) have been measured in the nuclei 156 Dy, 157 Dy, and 158 Dy using the recoil-distance technique together with inverse reactions of the type Mg( 136 Xe,xn). The applied method, which benefited from the high velocities of the fusion residues as well as from improvements of the recoil-distance technique, allowed us to determine liefetimes and feeding times down to 0.1 ps. Below the first backbending the resultant B(E2) values in the ground-state band of sup(156,158)Dy increase faster with increasing rotational frequency than expected for rigid rotors, reaching values similar to those observed for the well-deformed neutron-rich Dy isotopes. In contrast to this, the E2-transition probabilities between high-spin states are clearly retarded. The retardation gradually evolves from the rotation alignment of nucleons and indicates deformation changes most likely towards a triaxial shape. From the analysis of the side-feeding times of the high-spin yrast states it could be furthermore deduced that the E2 component of the preyrast γ-decay stems from transitions along highly collective bands. (orig.)

  7. Unexpected high-energy γ emission from decaying exotic nuclei

    Directory of Open Access Journals (Sweden)

    A. Gottardo

    2017-09-01

    Full Text Available The N=52 Ga83 β decay was studied at ALTO. The radioactive 83Ga beam was produced through the ISOL photofission technique and collected on a movable tape for the measurement of γ-ray emission following β decay. While β-delayed neutron emission has been measured to be 56–85% of the decay path, in this experiment an unexpected high-energy 5–9 MeV γ-ray yield of 16(4% was observed, coming from states several MeVs above the neutron separation threshold. This result is compared with cutting-edge QRPA calculations, which show that when neutrons deeply bound in the core of the nucleus decay into protons via a Gamow–Teller transition, they give rise to a dipolar oscillation of nuclear matter in the nucleus. This leads to large electromagnetic transition probabilities which can compete with neutron emission, thus affecting the β-decay path. This process is enhanced by an excess of neutrons on the nuclear surface and may thus be a common feature for very neutron-rich isotopes, challenging the present understanding of decay properties of exotic nuclei.

  8. Particle-hole intruder levels in {sup 67}Cu, collectivity, monopole shifts, and the hockey-stick behaviour of l - 1/2 5/2{sup -} levels in neutron-rich odd-mass Cu nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Walters, W B; Chiara, C J, E-mail: wwalters@umd.edu [University of Maryland, College Park, MD 20742 (United States)

    2011-01-01

    A new sequence of gamma rays with energies of 572, 499, 585, and 674 keV has been identified in {sup 67}Cu populating the 7/2{sup -} level at 2362 keV. Owing to the strong population of the 2362-keV level via an l = 3 proton pickup reaction, that level is assigned to be an f{sub 7/2}{sup -1} 2-particle-1-hole 'intruder' proton configuration, and the new levels are found to form a sequence consistent with intruder sequences in the adjacent odd-mass Cu isotopes and in the odd-mass Sb isotopes. The changing position of the intruder sequence in the odd-mass Cu isotopes is discussed and related to the onset of collectivity associated with the presence of g{sub 9/2} neutrons beyond N = 40. The increase in collectivity is also discussed for a number of isotonic and isotopic chains as more protons or neutrons, respectively, are added beyond an oscillator shell boundary. For most of these systems, the l -1/2 levels show a systematic 'hockey-stick-like' behaviour with a sharp decrease in energy with the addition of the first protons or neutrons, owing to both the added collectivity and the tensor interaction, and then a lower slope when collectivity changes are diminished and only the tensor interaction is influencing the changes in level positions.

  9. Particle-hole intruder levels in 67Cu, collectivity, monopole shifts, and the hockey-stick behaviour of ell - 1/2 5/2- levels in neutron-rich odd-mass Cu nuclei

    Science.gov (United States)

    Walters, W. B.; Chiara, C. J.

    2011-01-01

    A new sequence of gamma rays with energies of 572, 499, 585, and 674 keV has been identified in 67Cu populating the 7/2- level at 2362 keV. Owing to the strong population of the 2362-keV level via an ell = 3 proton pickup reaction, that level is assigned to be an f7/2-1 2-particle-1-hole "intruder" proton configuration, and the new levels are found to form a sequence consistent with intruder sequences in the adjacent odd-mass Cu isotopes and in the odd-mass Sb isotopes. The changing position of the intruder sequence in the odd-mass Cu isotopes is discussed and related to the onset of collectivity associated with the presence of g9/2 neutrons beyond N = 40. The increase in collectivity is also discussed for a number of isotonic and isotopic chains as more protons or neutrons, respectively, are added beyond an oscillator shell boundary. For most of these systems, the ell -1/2 levels show a systematic "hockey-stick-like" behaviour with a sharp decrease in energy with the addition of the first protons or neutrons, owing to both the added collectivity and the tensor interaction, and then a lower slope when collectivity changes are diminished and only the tensor interaction is influencing the changes in level positions.

  10. Investigations of neutron-rich nuclei at the dripline through their analogue states : The cases of $^{10}$Li - $^{10}$Be (T=2) and $^{17}$C - $^{17}$N (T=5/2)

    CERN Multimedia

    2002-01-01

    We propose to study the elastic resonance scattering reactions $^{9}$Li+p and $^{16}$C+p to investigate the energies, spins and parities of the lowest T=2 states in $^{10}$Be and the T=5/2 states in $^{17}$N. These are analogue states of the ground states and first excited states in $^{10}$Li and $^{17}$C.

  11. Isobars in nuclei

    International Nuclear Information System (INIS)

    Beurtey, R.

    1975-01-01

    The present situation of the theoretical studies and experimental material concerning the potential presence of virtual nucleon excited states (isobars) in nuclei is reported. Three particular aspects are examined: the theoretical work devoted to the isobar content of nuclei (especially deuteron), the experimental material concerning isobar exchange and the attempts to obtain a direct evidence for such objects in the deuteron (spectator method) [fr

  12. Nuclei in high forms

    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

  13. Eta mesons in nuclei

    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

  14. The analysis of predictability of recent alpha decay formulae and the alpha partial half-lives of some exotic nuclei

    International Nuclear Information System (INIS)

    Dasgupta-Schubert, N.; Reyes, M. A.; Tamez, V. A.

    2009-01-01

    Alpha decay is one of the two main decay modes of the heaviest nuclei, (SHE), and constitutes one of the dominant decay modes of highly neutron deficient medium mass nuclei ('exotics'). Thus identifying and characterizing the alpha decay chains form a crucial part of the identification of SHE. We report the extension of the previously developed method for the detailed and systematic investigation of the reliability of the three main extant analytical formulae of alpha decay half-lives: the generalized liquid drop model based formula of Royer et al. (FR), the Sobiczewski modified semi-empirical Viola-Seaborg formula (VSS) and the recent phenomenological formula of Sobiczewski and Parkhomenko (SP).

  15. Effect of a neutron skin on collective dipoles modes in nuclei

    International Nuclear Information System (INIS)

    Warner, D.D.; Van Isacker, P.; Nagarajan, M.A.

    1992-01-01

    One of the principal motivations for accelerated radioactive beams is to probe nuclear structure at the limits of nuclear stability. For neutron-rich nuclei, an indication of the new phenomena which may occur has already appeared, in the guise of the neutron halo discovered in very light nuclei. More generally, a steadily increasing neutron skin thickness is expected as the neutron excess increases. The presence of such a mantle of dominantly neutron matter will then particularly affect the properties of collective modes involving the out-of-phase motion of neutrons and protons. This paper explores the effect of the neutron skin thickness on the isovector M1 and E1 modes in medium and heavy mass nuclei. A simple model is used, couched in terms of classical oscillations of neutron and proton densities. The treatment includes the open-quotes pygmyclose quotes E1 mode, which corresponds to motion of the core against the loosely-bound neutrons in the mantle and predicts a significant lowering of this mode, even at relatively modest values of the skin thickness

  16. Investigating the nuclear structure of the neutron-rich odd-mass Fe isotopes, in the $\\beta$-decay of their parent - Mn

    CERN Document Server

    AUTHOR|(CDS)2079133; Van Duppen, Piet

    For many years the shell structure of the nucleus, originally proposed by Mayer and Haxel, predicting certain energy gaps at specific proton and/or neutron numbers, has been consistent with the experimental findings at or near the line of stability. These nuclei exhibit a sequence of magic numbers – 2, 8, 20, 28, 50, 82, which is different from the one calculated using only a Harmonic Oscillator potential: 2, 8, 20, 40, 70... The strong spin-orbit term, added to the latter potential by Mayer and Haxel, is a necessary requirement for a successful description of these quantum systems, which lowers the energy orbitals with higher spins directly affecting the l = 4 (1$g_{9/2}$) orbit by reducing the gap at N = 40 and creating the N = 50 one. With the development of more exotic radioactive beams, however, it has been observed that for nuclei away from the stability line the traditional shell gaps have weakened, while new energy gaps have emerged instead. It has been further realized that the residual nucleon- nu...

  17. Observation of New Neutron-rich Isotopes among Fission Fragments from In-flight Fission of 345 MeV/nucleon 238U: Search for New Isotopes Conducted Concurrently with Decay Measurement Campaigns

    Science.gov (United States)

    Shimizu, Yohei; Kubo, Toshiyuki; Fukuda, Naoki; Inabe, Naohito; Kameda, Daisuke; Sato, Hiromi; Suzuki, Hiroshi; Takeda, Hiroyuki; Yoshida, Koichi; Lorusso, Giuseppe; Watanabe, Hiroshi; Simpson, Gary S.; Jungclaus, Andrea; Baba, Hidetada; Browne, Frank; Doornenbal, Pieter; Gey, Guillaunme; Isobe, Tadaaki; Li, Zhihuan; Nishimura, Shunji; Söderström, Pär-Anders; Sumikama, Toshiyuki; Taprogge, Jan; Vajta, Zsolt; Wu, Jin; Xu, Zhengyu; Odahara, Atsuko; Yagi, Ayumi; Nishibata, Hiroki; Lozeva, Radomira; Moon, Changbum; Jung, HyoSoon

    2018-01-01

    The search for new isotopes using the in-flight fission of a 238U beam has been conducted concurrently with decay measurements, during the so-called EURICA campaigns, at the RIKEN Nishina Center RI Beam Factory. Fission fragments were analyzed and identified in flight using the BigRIPS separator. We have identified the following 36 new neutron-rich isotopes: 104Rb, 113Zr, 116Nb, 118,119Mo, 121,122Tc, 125Ru, 127,128Rh, 129,130,131Pd, 132Ag, 134Cd, 136,137In, 139,140Sn, 141,142Sb, 144,145Te, 146,147I, 149,150Xe, 149,150,151Cs, 153,154Ba, and 154,155,156,157La.

  18. Coulomb- and nuclear-induced break-up of halo nuclei at bombarding energies around the Coulomb barrier

    Energy Technology Data Exchange (ETDEWEB)

    Dasso, C.H. [Niels Bohr Inst., Copenhagen (Denmark); Guisado, J.L. [Niels Bohr Inst., Copenhagen (Denmark); Lenzi, S.M. [Niels Bohr Inst., Copenhagen (Denmark)]|[Padua Univ. (Italy). Dipt. di Fisica]|[Istituto Nazionale di Fisica Nucleare, Padua (Italy); Vitturi, A. [Padua Univ. (Italy). Dipt. di Fisica]|[Istituto Nazionale di Fisica Nucleare, Padua (Italy)

    1996-02-05

    We investigate the relative importance of the Coulomb and nuclear fields to induce the break-up of neutron-rich nuclei such as {sup 11}Li at energies close to the Coulomb barrier. We assume that the mechanism that leads to the separation is the excitation of a low-lying dipole mode in which the weakly-bound neutron halo performs a collective oscillation against the residual nuclear core. To this end we exploit semiclassical prescriptions that are adequate to calculate not only the average break-up probabilities but also to estimate the size of fluctuations about the quantal expectation values. Possible outcomes are explored as a function of both bombarding energy and impact parameter. Consequences of the couplings for elastic scattering and fusion processes are also discussed. (orig.).

  19. Towards a non empirical description of heavy nuclei

    International Nuclear Information System (INIS)

    Duguet, Thomas

    2012-01-01

    Since the defence of my Ph.D. thesis in September 2002, I have essentially devoted nine years of research activity to advancing the formal understanding and enhancing the predictive power of SR and MR EDF approaches to structure and reaction properties of medium-to-heavy mass nuclei. In the most recent years, I have engaged myself into developing innovative ab-initio many-body methods applicable to medium-mass open-shell nuclei. On the long term, my two main objectives are (i) to advancing many-body methods and the understanding of many-fermion systems in general and (ii) to reducing decisively the phenomenological character of methods applicable to systems made out of a few tens to a few hundreds of fermions by addressing the points raised in the above introduction. The present document does not aim at summarizing those ten years of research activity. Rather, I made the choice to report in some details on three selected topics that are somewhat representative of my overall contribution to the field. The first part (Sec. II) describes an in-depth re-analysis of the concept of single-nucleon shell structure in the context of many-fermion systems. The second part (Sec. III) summarizes recent advances towards a more rigorous formulation of the MR-EDF method and discusses the corresponding remaining difficulties as well as ways under current development to overcome them. The third part (Sec. IV) discusses the on-going quest towards a microscopic description of superfluidity in nuclei and reports on the first-ever ab-initio calculations of open-shell medium-mass nuclei based on Self-consistent Gorkov Green's function theory. Although representative, the three above topics only cover a fraction of my research activity since my Ph.D. thesis defence. Consequently several other studies I have been involved with are briefly summarized in apps. A-E. For completeness, my publication list is also provided as an appendix. Last but not least, it is essential to stress that many

  20. How atomic nuclei cluster.

    Science.gov (United States)

    Ebran, J-P; Khan, E; Nikšić, T; Vretenar, D

    2012-07-18

    Nucleonic matter displays a quantum-liquid structure, but in some cases finite nuclei behave like molecules composed of clusters of protons and neutrons. Clustering is a recurrent feature in light nuclei, from beryllium to nickel. Cluster structures are typically observed as excited states close to the corresponding decay threshold; the origin of this phenomenon lies in the effective nuclear interaction, but the detailed mechanism of clustering in nuclei has not yet been fully understood. Here we use the theoretical framework of energy-density functionals, encompassing both cluster and quantum liquid-drop aspects of nuclei, to show that conditions for cluster formation can in part be traced back to the depth of the confining nuclear potential. For the illustrative example of neon-20, we show that the depth of the potential determines the energy spacings between single-nucleon orbitals in deformed nuclei, the localization of the corresponding wavefunctions and, therefore, the degree of nucleonic density clustering. Relativistic functionals, in particular, are characterized by deep single-nucleon potentials. When compared to non-relativistic functionals that yield similar ground-state properties (binding energy, deformation, radii), they predict the occurrence of much more pronounced cluster structures. More generally, clustering is considered as a transitional phenomenon between crystalline and quantum-liquid phases of fermionic systems.

  1. Structure of tellurium nuclei

    International Nuclear Information System (INIS)

    Cizewski, J.A.; Henry, R.G.; Lee, C.S.

    1991-01-01

    The tellurium nuclei with two protons outside of the Z = 50 shell closure exhibit a complicated structure with signatures of collective vibrational, two-quasiparticle, possibly moderately deformed intruder configurations. To study further the structure of the tellurium nuclei the authors made extensive measurements of the (α,xnγ) reactions on even Sn targets, populating excitations in even- and odd-mass Te nuclei up to moderate angular momenta. By examining limits on possible intraband transitions, results suggest that a possible rotational band structure is not supported by the data, since intraband transitions are of comparable E2 strength to interband transitions. In the odd-A isotopes they concentrated on identifying the higher angular momentum negative-parity states (which probe the role of the h 11/2 neutron in the core), and the search for non-yrast negative-parity states, which are a sensitive measure of the shape of the collective excitations

  2. Vibrations in deformed nuclei

    International Nuclear Information System (INIS)

    Aprahamian, A.

    1992-01-01

    Quadrupole oscillations around a deformed shape give rise to vibrations in deformed nuclei. Single phonon vibrations of K = 0 (β) and K = 2 (γ) are a systematic feature in deformed nuclei, but the existence of multi-phonon vibrations had remained an open question until the recently reported results in 168 Er. In this nucleus, a two-phonon K = 4(γγ) band was observed at approximately 2.5 times the energy of the single γ vibration. The authors have studied several deformed rare-earth nuclei using the ( 4 He,2n) reaction in order to map out the systematic behavior of these multi-phonon vibrations. Recently, they have identified a similar K = 4 band in 154 Gd

  3. Ground state properties of neutron-rich Mg isotopes the "island of inversion" studied with laser and $\\beta$-NMR spectroscopy

    CERN Document Server

    Kowalska, M

    2006-01-01

    Studies in regions of the nuclear chart in which the model predictions of properties of nuclei fail can bring a better understanding of the strong interaction in the nuclear medium. To such regions belongs the so called "island of inversion" centered around Ne, Na and Mg isotopes with 20 neutrons in which unexpected ground-state spins, large deformations and dense low-energy spectra appear. This is a strong argument that the magic N=20 is not a closed shell in this area. In this thesis investigations of isotope shifts of stable $^{24-26}$Mg, as well as spins and magnetic moments of short-lived $^{29,31}$Mg are presented. The successful studies were performed at the ISOLDE facility at CERN using collinear laser and $\\beta$-NMR spectroscopy techniques. The isotopes were investigated as single-charged ions in the 280 nm transition from the atomic ground state $^2\\!$S$_{1/2}$ to one of the two lowest excited states $^2\\!$P$_{1/2 ,\\,3/2}$ using continuous wave laser beams. The isotope-shift measurements with fluor...

  4. Long-lived K isomer and enhanced γ vibration in the neutron-rich nucleus 172 Dy: Collectivity beyond double midshell

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, H.; Zhang, G. X.; Yoshida, K.; Walker, P. M.; Liu, J. J.; Wu, J.; Regan, P. H.; Söderström, P. -A.; Kanaoka, H.; Korkulu, Z.; Lee, P. S.; Nishimura, S.; Yagi, A.; Ahn, D. S.; Alharbi, T.; Baba, H.; Browne, F.; Bruce, A. M.; Carroll, R. J.; Chae, K. Y.; Dombradi, Zs.; Doornenbal, P.; Estrade, A.; Fukuda, N.; Griffin, C.; Ideguchi, E.; Inabe, N.; Isobe, T.; Kanaya, S.; Kojouharov, I.; Kondev, F. G.; Kubo, T.; Kubono, S.; Kurz, N.; Kuti, I.; Lalkovski, S.; Lane, G. J.; Lee, C. S.; Lee, E. J.; Lorusso, G.; Lotay, G.; Moon, C. -B.; Nishizuka, I.; Nita, C. R.; Odahara, A.; Patel, Z.; Phong, V. H.; Podolyák, Zs.; Roberts, O. J.; Sakurai, H.; Schaffner, H.; Shand, C. M.; Shimizu, Y.; Sumikama, T.; Suzuki, H.; Takeda, H.; Terashima, S.; Vajta, Zs.; Valiente-Dóbon, J. J.; Xu, Z. Y.

    2016-09-01

    The level structure of 172Dy has been investigated for the first time by means of decay spectroscopy following in-flight fission of a 238U beam. A long-lived isomeric state with T1/2 = 0.71(5) s and Kπ = 8- has been identified at 1278 keV, which decays to the ground-state and γ -vibrational bands through hindered electromagnetic transitions, as well as to the daughter nucleus 172Ho via allowed β decays. The robust nature of the Kπ = 8- isomer and the ground-state rotational band reveals an axially-symmetric structure for this nucleus. Meanwhile, the γ -vibrational levels have been identified at unusually low excitation energy compared to the neighboring well-deformed nuclei, indicating the significance of the microscopic effect on the non-axial collectivity in this doubly mid-shell region. The underlying mechanism of enhanced γ vibration is discussed in comparison with the deformed Quasiparticle Random-Phase Approximation based on a Skyrme energy-density functional.

  5. Weak interactions with nuclei

    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

  6. Disintegration of comet nuclei

    Science.gov (United States)

    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.

  7. 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

  8. Mesons and light nuclei

    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)

  9. Nucleons in nuclei (II)

    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

  10. Alpha clustering in nuclei

    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)

  11. Study of single particle properties of nuclei in the region of the "island of inversion" by means of neutron-transfer reactions

    CERN Multimedia

    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 ...

  12. Limits to the formation of hot fusion nuclei in nucleus-nucleus collisions

    International Nuclear Information System (INIS)

    Peter, J.; Tamain, B.

    1987-01-01

    The maximum temperature which can be sustained by a nucleus is discussed. Methods used to measure the temperature; values measured in fusion reactors; theoretical investigations on the value of the limiting temperature; and information about dynamical limitations on excitation energy storage in nuclei are reviewed. It is concluded that thermalized fusion nuclei are formed at temperatures up to 5 MeV for heavy systems and 6 MeV for medium mass systems. Thermal energy in central nucleus-nucleus collisions might not exceed some saturation value due to two effects: a sharing of the deposited energy into compressional and thermal energies; and a dynamical competition between thermal energy deposition and fast pre-equilibrium emission

  13. Relativistic exotic nuclei as projectile beams. New perspectives of studies on the properties of nuclei; Relativistische exotische Kerne als Projektilstrahlen. Neue Perspektiven zum Studium der Kerneigenschaften

    Energy Technology Data Exchange (ETDEWEB)

    Geissel, H.

    1997-03-01

    Examinations of the production cross-sections and the kinematics permitted refinement of model concepts of the peripheral reactions in exotic nuclei at energies from 100 to 1000 A MeV. Due to the strong selectivity and resolution achieved it was possible to discover a large number of novel isotopes at the fragment separator FRS, despite the relatively low projectile beam intensities of the SIS. The two twice magic nuclei found, Ni 78 and Sn 100, are particularly interesting, as they could not be measured so far with other experimental systems. Fission of relativistic uranium ions proved to be a particularly successful process yielding many medium-heavy, neutron-rich nuclei. Insight into the structure of light neutron halos could be improved. The superlarge spatial dimensions of the nuclear halos is discussed. (orig./CB) [Deutsch] Die Untersuchungen der Produktionsquerschnitte und der Kinematik fuehr ten zu einer Verfeinerung der Modellvorstellungen der peripheren Kernr eaktionen an exotischen Kernen bei Energien im Bereich von 100- 1000 A MeV. Die hohe Selektivitaet und Aufloesung waren die Voraussetzung, da ss schon bei den vergleichsweise niedrigen Projektilstrahlintensitaete n des SIS eine grosse Anzahl von neuen Isotopen am Fragmentseparator F RS entdeckt werden konnten. Besonders erwaehnenswert sind die beiden d oppelt magischen Kerne Ni 78 und Sn 100, die mit anderen experimentel len Anlagen vorher nicht zugaenglich waren.Die Spaltung relativistisch er Uranionen hat sich als eine besonders ergiebige Quelle fuer mittels chwere neutronenreiche Kerne erwiesen. Die Kenntnisse der Struktur lei chter Neutronen- Halokerne konnten erweitert werden. Die uebergrosse r aeumliche Ausdehnung der Halokerne wurde aufgezeigt.

  14. Shape Deformations in Atomic Nuclei

    OpenAIRE

    Hamamoto, Ikuko; Mottelson, Ben R.

    2011-01-01

    The ground states of some nuclei are described by densities and mean fields that are spherical, while others are deformed. The existence of non-spherical shape in nuclei represents a spontaneous symmetry breaking.

  15. Unified studies of structure and reactions in light unstable nuclei

    Directory of Open Access Journals (Sweden)

    Ito Makoto

    2016-01-01

    Full Text Available The generalized two-center cluster model (GTCM, which can treat covalent, ionic and atomic configurations in general systems with two inert cores plus valence nucleons, is formulated in the basis of the microscopic cluster model. In this model, the covalent configurations constructed by the molecular orbital (MO method and the atomic (or ionic configuration obtained by the valence bonding (VB method can be described in a consistent manner. GTCM is applied to the light neutron-rich system, 10,12Be = α + α + XN (X = 2,4, and the unified studies of the structural changes and the reaction problem are performed. In the structure study, the calculated energy levels are characterized in terms of the chemical bonding like structures, such as the covalent MO or ionic VB structures. The chemical bonding structures changes from level to level within a small energy interval. In the unbound region, the structure problem with the total system of α + α + XN and the reaction problem, induced by the collision of an asymptotic VB state of α+6,8He, are combined by GTCM. The properties of unbound resonant states are discussed in a close connection to the reaction mechanism, and some enhancement factors originated from the properties of the intrinsic states are predicted in the reaction observables. The unified calculation of the structures and the reactions is applied to the Coulomb shift problem in the mirror system, such the 10Be and 10C nuclei. The Coulomb displacement energy of the mirror systems are discussed.

  16. Fission fragments mass distributions of nuclei populated by the multinucleon transfer channels of the 18O+232Th reaction

    Directory of Open Access Journals (Sweden)

    R. Léguillon

    2016-10-01

    Full Text Available It is shown that the multinucleon transfer reactions is a powerful tool to study fission of exotic neutron-rich actinide nuclei, which cannot be accessed by particle-capture or heavy-ion fusion reactions. In this work, multinucleon transfer channels of the 18O+232Th reaction are used to study fission of fourteen nuclei 231,232,233,234Th, 232,233,234,235,236Pa, and 234,235,236,237,238U. Identification of fissioning nuclei and of their excitation energy is performed on an event-by-event basis, through the measurement of outgoing ejectile particle in coincidence with fission fragments. Fission fragment mass distributions are measured for each transfer channel, in selected bins of excitation energy. In particular, the mass distributions of 231,234Th and 234,235,236Pa are measured for the first time. Predominantly asymmetric fission is observed at low excitation energies for all studied cases, with a gradual increase of the symmetric mode towards higher excitation energy. The experimental distributions are found to be in general agreement with predictions of the fluctuation–dissipation model.

  17. Measurements of r-process nuclei

    OpenAIRE

    Kratz, K L

    2001-01-01

    Progress in the astrophysical understanding of r-process nucleosynthesis also depends on the knowledge of nuclear-physics quantities of extremely neutron-rich isotopes. In this context, experiments at CERN-ISOLDE have played a pioneering role in exploring new shell-structure far from stability. Possible implications of new nuclear-data input on the reproduction of r-abundance observations are presented.

  18. On the pairing effects in triaxial nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Oudih, M. R. [Laboratoire de Physique Théorique, Faculté de Physique,USTHB BP 32, El Alia, 16111 Bab Ezzouar, Algiers (Algeria); Fellah, M.; Allal, N. H. [Centre de Recherche Nucléaire d' Alger, 2 Bd. Frantz Fanon, BP. 399 Alger-Gare, Algiers, Algeria and Laboratoire de Physique Théorique, Faculté de Physique,USTHB BP 32, El Alia, 16111 Bab Ezzouar, Algiers (Algeria)

    2014-03-05

    Triaxial deformation effect on the pairing correlations is studied in the framework of the Skyrme Hartree-Fock-Bogoliubov theory. Quantities such as binding energy, gap parameter and particle-number fluctuation are considered in neutron-rich Mo isotopes. The results are compared with those of axially symmetric calculation and with available experimental data. The role played by the particle-number projection is outlined.

  19. Nuclei in Astrophysics

    Science.gov (United States)

    Penionzhkevich, Yu. E.

    2016-06-01

    This work is an attempt to present some problems on the evolution of the Universe: the nucleosynthesis and cosmochronology from the standpoint of physics of particles and nuclei, in particular with the use of the latest results, obtained by means of radioactive nuclear beams. The comparison is made between the processes taking place in the Universe and the mechanisms of formation and decay of nuclei, as well as of their interaction at different energies. Examples are given to show the capabilities of nuclearphysics methods for studying cosmic objects and properties of the Universe. The results of investigations in nuclear reactions, induced by radioactive nuclear beams, make it possible to analyze the nucleosynthesis scenario in the region of light elements in a new manner.

  20. Pion coupling to nuclei

    International Nuclear Information System (INIS)

    Dumbrajs, O.

    1981-01-01

    The concept of the pion-nucleus coupling constants is discussed. Methods of their determination are reviewed. These include: forward dispersion relations, extrapolation of differential cross sections to the poles in the angular variable, analysis of data on electromagnetic form factors with the use of the PCAC and CVC hypotheses, pion photoproduction at threshold and low-energy theorems. Our present knowledge of the pion coupling to the He, Li, Be, C, N and O nuclei is summarized. (author)

  1. Chaotic behavior in nuclei

    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

  2. Reaction Dynamics and Nuclear Structure Studies of n-Rich Nuclei Around 48Ca via Deep Inelastic Collisions with Heavy-Ions

    International Nuclear Information System (INIS)

    Leoni, S.

    2011-01-01

    The population and γ decay of neutron rich nuclei around 48 Ca has been measured at Legnaro National Laboratory with the PRISMA-CLARA setup, using deep-inelastic collisions on 64 Ni, at 5.9 MeV/A. The reaction properties of the main products are investigated, focusing on total cross-sections and energy integrated angular distributions. Gamma spectroscopy studies are also performed for the most intense transfer channels, making use of angular distributions and polarization measurements to firmly establish spin and parity of the excited states. In the case of 49 Ca candidates for particle-core couplings are investigated and interpreted on basis of lifetime measurements and comparison with model predictions. (author)

  3. High performance liquid chromatographic separation of beryllium from some transition metals produced in high energy proton irradiations of medium mass elements: measurement of (p,7Be) cross sections

    International Nuclear Information System (INIS)

    Fassbender, M.; Spellerberg, S.; Qaim, S.M.

    1996-01-01

    A high performance liquid chromatographic (HPLC) method was developed for the separation of 7 Be formed in high energy proton irradiation of medium mass elements like Fe, Cu etc. The bulk of the target material was removed in a preseparation step. Thereafter beryllium was obtained in a high purity within a few minutes elution time using a mixture of 5 mM citric acid and 1.0 mM pyridinedicarboxylic acid as eluent and a SYKAM KO2 analytical cation-exchange column. The effect of Be-carrier on the quality of separation was investigated. The quality of separation deteriorated with the increasing Be-carrier column loading. A certain amount of Be-carrier was, however, necessary in order to quantitate the results. By using low Be-carrier amounts (∝100 μg) and determining the elution yield via a conductometric method, it was possible to obtain quantitative separation results. Besides the analytical column, a semi-preparative column was also used, and the Be separation yield determined gravimetrically. The cross sections for the (p, 7 Be) process on Cu obtained using the two separation columns (analytical and semipreparative) and the two separation yield determination methods agreed within 15%. (orig.)

  4. Universality and Halo Nuclei

    Directory of Open Access Journals (Sweden)

    Tomio L.

    2010-04-01

    Full Text Available Universal aspects of few-body systems will be reviewed motivated by recent interest in atomic and nuclear physics. The critical conditions for the existence of excited states in three-body systems with two-identical particles will be explored. In particular, we consider halo nuclei that can be modeled as three-body nuclear systems, with two halo neutrons and a core. In this context, we also discuss the low-energy neutron−19C elastic scattering, near the conditions for the app earance of an Efimov state.

  5. Anomalous carbon nuclei

    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

  6. Particles and nuclei, letters

    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

  7. Active galactic nuclei

    CERN Document Server

    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

  8. Active galactic nuclei

    CERN Document Server

    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

  9. Stability of superheavy nuclei

    Science.gov (United States)

    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.

  10. Rotating clusters in nuclei

    International Nuclear Information System (INIS)

    Pauling, L.; Robinson, A.B.

    1975-01-01

    Values of R, the radius of rotation of the rotating cluster, are calculated from the energy of the lowest 2 + level of even-even nuclei with the assumption that the cluster consists of p 2 or n 2 respectively, for N or P magic, and of a helion (α) for N or P differing from a magic number by +-2. The values as a function of A show a zigzag course, which is correlated with the polyspheron structure of the nuclei. If the mantle is not overcrowded the cluster glides over the surface of the mantle and the value of R increases by one spheron diameter, about 3.2 fm. At certain values of N a change in structure of the nucleus occurs, with increase in radius of the core by half a spheron diameter, permitting the cluster to drop back into the mantle, with decrease in R by half a spheron diameter. In the lanthanon region of permanent prolate deformation the rotating cluster is a polyhelion, containing the number of helions permitted by the difference between Z or N and the nearest magic number, and in the actinon region it contains all the nucleons beyond 208 Pb, with maximum p 10 n 16 . An explanation is given of the difference between these regions. (author)

  11. Theory of magic nuclei

    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.)

  12. 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

  13. 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)

  14. Neutrino interactions with nuclei

    International Nuclear Information System (INIS)

    Walecka, J.D.

    1983-01-01

    We examine tests of the Glashow-Weinberg-Salam (GWS) Standard Theory of Electroweak Interactions. The tests are model-independent in the sense that they are relations between experimental quantities that are direct consequences of the GWS theory, but they are independent of the detailed structure of the nucleus. Such relationships were anticipated by Weinberg. Neutrino reactions with nuclei are considered, focusing largely on charged-lepton production, and it is demonstrated that intermediate-energy neutrino reactions have a central and unique role to play in our understanding of semileptonic weak interactions. This point is illustrated by discussing a complete kinematic experiment on the nucleon. A discussion of what neutrino reactions could teach us about nuclear structure is also given

  15. 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

  16. Particles and nuclei, letters

    International Nuclear Information System (INIS)

    2000-01-01

    The present collection of letters from JINR, Dubna, contains eight separate records on liquid argon pollution tests of the ATLAS detector materials at IBR-2 reactor in Dubna, irradiation tests of readout chain components of the ATLAS liquid argon calorimeters, study of neutron induced outgassing from tungsten alloy for ATLAS FCAL, yields of nuclear reaction products from a thick beryllium target bombarded by beams of 7 Li, 11 B and 15 N ions as well as on the mass surface and the properties of nuclides close to hypothetic doubly magic lead-164, the Web-site of information-diagnostic system of IBR-2 pulsed neutron source state, discovery of η-mesic nuclei and calculation of the ion angular distributions after the ionization in ion-atom collisions

  17. Clusters in nuclei

    CERN Document Server

    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...

  18. Pion production in nuclei

    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)

  19. Nuclear Structure Studies of Exotic Nuclei with Radioactive Ion Beams A Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Winger, Jeff Allen [Mississippi State Univ., Mississippi State, MS (United States)

    2016-04-21

    Beta-decay spectroscopy provides important information on nuclear structure and properties needed to understand topics as widely varied as fundamental nuclear astrophysics to applied nuclear reactor design. However, there are significant limitations of our knowledge due to an inability to experimentally measure everything. Therefore, it is often necessary to rely on theoretical calculations which need to be vetted with experimental results. The focus of this report will be results from experimental research performed by the Principal Investigator (PI) and his research group at Mississippi State University in which the group played the lead role in proposing, implementing, performing and analyzing the experiment. This research was carried out at both the National Superconduction Cyclotron Laboratory (NSCL) at Michigan State University and the Holifield Radioactive Ion Beam Facility (HRIBF) at Oak Ridge National Laboratory. The primary emphasis of the research was the use of \\bdec spectroscopy as a tool to understand the evolution of nuclear structure in neutron-rich nuclei which could then be applied to improve theory and to increase the overall knowledge of nuclear structure.

  20. 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.

  1. 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)

  2. Quarks in Few Body Nuclei

    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.

  3. Laser spectroscopy on neutron rich sodium isotopes

    CERN Document Server

    Huber, G; Jacquinot, P; Juncar, P; Klapisch, Robert; Liberman, S; Pinard, J; Thibault, C; Vialle, J L

    1976-01-01

    The authors describe results with single-mode dye lasers in high- resolution atomic line spectroscopy. Optical pumping and magnetic resonance detection of Na D-lines provide values of static nuclear groundstate properties.

  4. Laser Spectroscopy of Neutron Rich Bismuth Isotopes

    CERN Multimedia

    2002-01-01

    %IS344 :\\\\ \\\\ The aim of the experiment is to measure the optical isotope shifts and hyperfine structures of bismuth isotopes across the N=126 shell closure in order to extract the change in mean square charge radii ($\\delta\\langle r^{2}\\rangle$) and static moments. These include the first isotones of lead to be measured directly above the shell closure and will provide new information on the systematics of the kink ($\\delta\\langle r^{2}\\rangle)$ seen in the lead isotopic chain. After two very successful runs the programme has been extended to include the neutron deficient isotopes below $^{201}$Bi to study the systematics across the $i_{13/2}$ neutron sub-shell closure at N=118.\\\\ \\\\ During the initial 2 runs (9 shifts) the isotope shifts and hyperfine structures of three new isotopes, $ ^{210,212,213}$Bi and the 9$^{-}$ isomer of $^{210}$Bi have been measured. The accuracy of the previous measurements of $^{205,206,208}$Bi have been greatly improved. The samples of $ ^{208,210,210^{m}}$Bi were prepared by c...

  5. The analysis of predictability of recent alpha decay formulae and the alpha partial half-lives of some exotic nuclei

    Science.gov (United States)

    Dasgupta-Schubert, N.; Reyes, M. A.; Tamez, V. A.

    2009-04-01

    Alpha decay is one of the two main decay modes of the heaviest nuclei, (SHE), and constitutes one of the dominant decay modes of highly neutron deficient medium mass nuclei ("exotics"). Thus identifying and characterizing the alpha decay chains form a crucial part of the identification of SHE. We report the extension of the previously developed method [1] for the detailed and systematic investigation of the reliability of the three main extant analytical formulae of alpha decay half-lives: the generalized liquid drop model based formula of Royer et al. [2] (FR), the Sobiczewski modified semi-empirical Viola-Seaborg formula [3] (VSS) and the recent phenomenological formula of Sobiczewski and Parkhomenko [4] (SP).

  6. The cochlear nuclei of snakes.

    Science.gov (United States)

    Miller, M R

    1980-08-15

    The cochlear nuclei of three burrowing snakes (Xenopeltis unicolor, Cylindrophis rufus, and Eryx johni) and three non-burrowing snakes (Epicrates cenchris, Natrix sipedon, and Pituophis catenifer) were studied. The posterior branch of the statoacoustic nerve and its posterior ganglion were destroyed and the degenerated nerve fibers and terminals traced to primary cochlear nuclei in 13 specimens of Pituophis catenifer. All these snake species possess three primary and one secondary cochlear nuclei. The primary cochlear nuclei consist of a small nucleus angularis located at the cerebello-medullary junction and a fairly large nucleus magnocellularis forming a dorsal cap over the cephalic end of the alar eminence. Nucleus magnocellularis may be subdivided into a medially placed group of rounder cells, nucleus magnocellularis medialis, and a laterally placed group of more ovate and paler-staining cells, nucleus magnocellularis lateralis. A small but well-defined secondary nucleus which showed no degenerated nerve terminals after nerve root section, nucleus laminaris, underlies the cephalic part of both nucleus magnocellularis medialis and nucleus magnocellularis lateralis. Larger and better-developed cochlear nuclei were found in burrowing species than in non-burrowing species of snakes. Of the three burrowing species studied, Xenopeltis showed the greatest development of cochlear nuclei; Eryx cochlear nuclei were not quite as large but were better differentiated than in Xenopeltis; and Cylindrophis cochlear nuclei were fairly large but not as well developed nor as well differentiated as in either Xenopeltis or Eryx. The cochlear nuclei of the three non-burrowing snakes, Epicrates, Natrix, and Pituophis, were not as large nor as well developed as those of the burrowing snakes. There is some, but not complete, correlation between cochlear development and papilla basilaris length and number of hair cells. Thus, Xenopeltis and Eryx, with well-developed cochlear nuclei

  7. Fission fragments mass distributions of nuclei populated by the multinucleon transfer channels of the {sup 18}O + {sup 232}Th reaction

    Energy Technology Data Exchange (ETDEWEB)

    Léguillon, R. [Advanced Science Research Center, Japan Atomic Energy Agency (JAEA), Tokai, Ibaraki 319-1195 (Japan); Nishio, K., E-mail: nishio.katsuhisa@jaea.go.jp [Advanced Science Research Center, Japan Atomic Energy Agency (JAEA), Tokai, Ibaraki 319-1195 (Japan); Hirose, K.; Makii, H.; Nishinaka, I.; Orlandi, R.; Tsukada, K. [Advanced Science Research Center, Japan Atomic Energy Agency (JAEA), Tokai, Ibaraki 319-1195 (Japan); Smallcombe, J. [Advanced Science Research Center, Japan Atomic Energy Agency (JAEA), Tokai, Ibaraki 319-1195 (Japan); TRIUMF, Vancouver, British Columbia V6T 2A3 (Canada); Chiba, S. [Laboratory for Advanced Nuclear Energy, Institute for Innovative Research, Tokyo Institute of Technology, N1-9, 2-12-1 Ookayama, Meguro, Tokyo 152-8550 (Japan); Aritomo, Y. [Faculty of Science and Engineering, Kindai University, Higashi-Osaka, 577-8502 (Japan); Ohtsuki, T. [Research Reactor Institute, Kyoto University, Kumatori-cho, Sennangun, Osaka 590-0494 (Japan); Tatsuzawa, R.; Takaki, N. [Graduate School of Engineering, Tokyo City University, Tokyo 158-8557 (Japan); Tamura, N.; Goto, S. [Graduate School of Science and Technology, Niigata University, Niigata 950-2181 (Japan); Tsekhanovich, I. [University of Bordeaux, 351 Cours de la Libration, 33405 Talence Cedex (France); Petrache, C.M. [Centre des Sciences Nucléaire et des Sciences de la Matière, Université Paris-Saclay, CNRS/IN2P3, 91406 Orsay (France); Andreyev, A.N. [Department of Physics, University of York, Heslington, York, YO10 5DD (United Kingdom); Advanced Science Research Center, Japan Atomic Energy Agency (JAEA), Tokai, Ibaraki 319-1195 (Japan)

    2016-10-10

    It is shown that the multinucleon transfer reactions is a powerful tool to study fission of exotic neutron-rich actinide nuclei, which cannot be accessed by particle-capture or heavy-ion fusion reactions. In this work, multinucleon transfer channels of the {sup 18}O + {sup 232}Th reaction are used to study fission of fourteen nuclei {sup 231,232,233,234}Th, {sup 232,233,234,235,236}Pa, and {sup 234,235,236,237,238}U. Identification of fissioning nuclei and of their excitation energy is performed on an event-by-event basis, through the measurement of outgoing ejectile particle in coincidence with fission fragments. Fission fragment mass distributions are measured for each transfer channel, in selected bins of excitation energy. In particular, the mass distributions of {sup 231,234}Th and {sup 234,235,236}Pa are measured for the first time. Predominantly asymmetric fission is observed at low excitation energies for all studied cases, with a gradual increase of the symmetric mode towards higher excitation energy. The experimental distributions are found to be in general agreement with predictions of the fluctuation–dissipation model.

  8. Selected properties of nuclei at the magic shell closures from the studies of E1, M1 and E2 transition rates

    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.

  9. The galactic census of high- and medium-mass protostars. II. Luminosities and evolutionary states of a complete sample of dense gas clumps

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Bo; Tan, Jonathan C.; Barnes, Peter J. [Department of Astronomy, University of Florida, FL 32611 (United States)

    2013-12-10

    The Census of High- and Medium-mass Protostars (CHaMP) is the first large-scale (280° < l < 300°, –4° < b < 2°), unbiased, subparsec resolution survey of Galactic molecular clumps and their embedded stars. Barnes et al. presented the source catalog of ∼300 clumps based on HCO{sup +}(1-0) emission, used to estimate masses M. Here we use archival midinfrared-to-millimeter continuum data to construct spectral energy distributions. Fitting two-temperature gray-body models, we derive bolometric luminosities, L. We find that the clumps have 10 ≲ L/L {sub ☉} ≲ 10{sup 6.5} and 0.1 ≲ L/M/[L {sub ☉}/M {sub ☉}] ≲ 10{sup 3}, consistent with a clump population spanning a range of instantaneous star-formation efficiencies from 0 to ∼50%. We thus expect L/M to be a useful, strongly varying indicator of clump evolution during the star cluster formation process. We find correlations of the ratio of warm-to-cold component fluxes and of cold component temperature with L/M. We also find a near-linear relation between L/M and Spitzer-IRAC specific intensity (surface brightness); thus, this relation may also be useful as a star-formation efficiency indicator. The lower bound of the clump L/M distribution suggests that the star-formation efficiency per free-fall time is ε{sub ff} < 0.2. We do not find strong correlations of L/M with mass surface density, velocity dispersion, or virial parameter. We find a linear relation between L and L{sub HCO{sup +}(1--0)}, although with large scatter for any given individual clump. Fitting together with extragalactic systems, the linear relation still holds, extending over 10 orders of magnitude in luminosity. The complete nature of the CHaMP survey over a several kiloparsec-scale region allows us to derive a measurement at an intermediate scale, bridging those of individual clumps and whole galaxies.

  10. 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.

  11. 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')

  12. Supersymmetry in nuclei

    CERN Document Server

    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...

  13. 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)

  14. Gluon density in nuclei

    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

  15. 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

  16. 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.

  17. Studies on short-lived fission products at the Mainz TRIGA reactor

    International Nuclear Information System (INIS)

    Trautmann, N.

    1974-01-01

    Neutron-rich nuclei of medium mass number are produced by thermal-neutron-induced fission of heavy elements, e.g., 235 U, 239 Pu, and 249 Cf. Pulse irradiations lead to an enhancement of the ratio of short-lived activities to the accompanying longer-lived components. One approach for investigating the properties of short-lived nuclei consists in a combination of rapid chemical separations with higher-resolution gamma spectroscopy. This is demonstrated by the isolation of neutron-rich isotopes of niobium by sorption on glass and of ruthenium by solvent extraction. Other rapid separation procedures from aqueous solutions are briefly summarized and a few examples for their application in nuclear fission- and delayed neutron studies are given. Some experiments with an on-line mass separator of the ISOLDE-type, using chemical targets, are described. (U.S.)

  18. Cavitation inception from bubble nuclei

    DEFF Research Database (Denmark)

    Mørch, Knud Aage

    2015-01-01

    The tensile strength of ordinary water such as tap water or seawater is typically well below 1 bar. It is governed by cavitation nuclei in the water, not by the tensile strength of the water itself, which is extremely high. Different models of the nuclei have been suggested over the years....... The cavitation nuclei may be free gas bubbles in the bulk of water, or interfacial gaseous voids located on the surface of particles in the water, or on bounding walls. The tensile strength of these nuclei depends not only on the water quality but also on the pressure-time history of the water. A recent model...... and associated experiments throw new light on the effects of transient pressures on the tensile strength of water, which may be notably reduced or increased by such pressure changes....

  19. 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

  20. Nuclei Isolation from Nematode Ascaris

    Science.gov (United States)

    Kang, Yuanyuan; Wang, Jianbin; Davis, Richard E.

    2017-01-01

    Preparing nuclei is necessary in a variety of experimental paradigms to study nuclear processes. In this protocol, we describe a method for rapid preparation of large number of relatively pure nuclei from Ascaris embryos or tissues that are ready to be used for further experiments such as chromatin isolation and ChIP-seq, nuclear RNA analyses, or preparation of nuclear extracts (Kang et al., 2016; Wang et al., 2016). PMID:29082294

  1. Coulomb excitation of proton rich nuclei 32Ar and 34Ar

    International Nuclear Information System (INIS)

    Lepyoshkina, Olga

    2013-01-01

    In the present thesis an investigation of the low-lying strength in the proton-rich nuclei 32 Ar and 34 Ar is reported. The earlier observation of low-lying dipole strength in neutron-rich nuclei and its interpretation with respect to basic nuclear properties (symmetry energy, skin thickness) initiated the investigation of this phenomenon in proton-rich nuclei. Macroscopically this so-called Pygmy strength could be interpreted with the resonant dipole oscillation of a proton-skin against an isospin-symmetric core. For nuclei like 32 Ar the occurrence of pronounced dipole strength is predicted in the lowenergy region between 8-10 MeV excitation energy. For the 34 Ar the pygmy strength is expected to drop sharply and vanish entirely for the N=Z nucleus 36 Ar. Using the Coulomb excitation method in inverse and complete kinematics at the LAND/R3B setup at GSI Helmholtzzentrum fuer Schwerionenforschung GmbH in Darmstadt, Germany, an experiment using radioactive 32 Ar and 34 Ar beams has been performed. The isotopes were obtained via fragmentation of a 825 AMeV primary 36 Ar beam on a 6.347g/cm 2 Be target. The produced proton-rich projectiles with a similar mass-to-charge ratio were separated from the primary beam and from other reaction products in flight using the Fragment Separator FRS. The selected and identified proton rich isotopes with a remaining energy of 650 AMeV were subsequently directed to a lead target of the LAND/R3B setup placed in Cave C. In order to determine the excitation energy after projectile excitation on the Pb target, all the products of the decay from the resonance are detected and identified (fragments, protons and gammas). The reconstruction of the excitation energy for one- and two-proton emission channels for 32 Ar and 34 Ar were derived from the particles momenta using the invariant mass technique in an event-by-event mode, allowing for an investigation of dipole strength appearance. After the experiment, all the detectors have been

  2. 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)

  3. Spinodal decomposition of atomic nuclei

    International Nuclear Information System (INIS)

    Chomaz, P.; Colonna, M.; Guarnera, A.

    1996-01-01

    Multifragmentation of atomic nuclei is discussed. It is shown that this description of the dynamics of first order phase transitions in infinite and finite system is now partially achieved. An important conclusion is that in some specific cases well-defined collective motions were initiating the self-organisation of the unstable matter in fragments. In the case of finite systems the possible signals kept from this early fragmentation stage can inform on the possible occurrence of a liquid-gas phase transition in nuclei. (K.A.)

  4. Measurement of Q{sub {beta}} values of neutron-rich Tc to Pd isotopes in the mass range A=110 to A=117; Messung von Q{sub {beta}}-Werten neutronenreicher Tc- bis Pd-Isotope im Massenbereich A=110 bis A=117

    Energy Technology Data Exchange (ETDEWEB)

    Kloeckl, Ingo

    2008-06-15

    The present work describes the measuring of Q{sub {beta}} values of {beta}-instable isotopes of Tc, Ru, Rh and Pd. The mass range A=110 to 117 comprises neutron-rich, short-living isotopes. Due to their small (fission) abundances, few data are known, especially regarding level schemes or gamma radiation. The proton-induced fission and a fast online mass separation was used to produce these nuclides in the IGISOL facility located in Jyvaeskylaein Finland. The {beta},{gamma},X coincidence apparatus used during the experiments allows measuring Q{sub {beta}} values as well as {gamma},X coincidences. The latter represent the basic input data for a calculation of Q{sub {beta}} values out of {beta},{gamma} coincidences. It is so possible to examine nuclides with incomplete level schemes; similarly, these level schemes can be extended using beta,gamma coincidence data. Twelve Q{sub {beta}} values of neutron-rich Tc to Pd isotopes could be determined, yielding nuclear masses, mass defects and neutron separation energies. Eight of them were determined for the first time; another one could be confirmed. For three more, the error of earlier values could be decreased by a factor of nearly ten. The resulting data are of interest for the review of nuclear mass models, they represent also input in astrophysical network calculations. (orig.)

  5. Proton scattering from unstable nuclei 20O, 30S, 34Ar: experimental study and models

    International Nuclear Information System (INIS)

    Khan, Elias

    2000-01-01

    Elastic and inelastic proton scattering from the unstable nuclei 20 O, 30 S and 34 Ar were measured in inverse kinematics at the Grand Accelerateur National d'Ions Lourds. Secondary beams of 20 O at 43 MeV/A, 30 S at 53 MeV/A and 34 Ar at 47 MeV/A impinged on a (CH 2 ) n target. Recoiling protons were detected in the silicon strip array MUST. Energies and angular distributions of the first 2 + and 3 - states were measured. A phenomenological analysis yields values of the deformation parameters β 2 and β 3 of 0.55 (6) and 0.35 (5) for 20 O, 0.32 (3) and 0.22 (4) for 30 S, 0.27 (2) and 0.39 (3) for 34 Ar, respectively, and allows the extraction of the ratio of neutron to proton transition matrix elements (M n /M p )/(N/Z) for 2 + states: 2.35 (37) for 20 O, 0.93 (20) for 30 S and 1.35 (28) for 34 Ar. Therefore the proton rich nuclei 30 S and 34 Ar show a 2 + excitation of isoscalar character whereas the excitation of 20 O is of isovector character. In order to perform a microscopic analysis of the data, we have developed a QRPA model, using three Skyrme interaction: SIII, SG2, SLy4. This model reproduces measured B(EL) values for the oxygen, sulfur and argon isotopic chains, whereas RPA calculations, which do not take pairing into account, underestimate these values. In the case of the QRPA model the energies of the first 2 + state are overestimated by about 1 MeV, but the evolution along the isotopic chains is well reproduced. (M n /M p )/(N/Z) ratios for the first 2 + state deduced from the microscopic analysis using QRPA are 1.98 for 20 O, 1.05 for 30 S and 1.00 for 34 Ar, in agreement with the conclusions of the phenomenological analysis. However important discrepancies are observed between the two types of analysis for other isotopes, in particular neutron rich argon and sulfur nuclei. (author)

  6. Electron scattering for exotic nuclei

    Indian Academy of Sciences (India)

    2014-11-04

    Nov 4, 2014 ... A brand-new electron scattering facility, the SCRIT Electron Scattering Facility, will soon start its operation at RIKEN RI Beam Factory, Japan. This is the world's first electron scattering facility dedicated to the structure studies of short-lived nuclei. The goal of this facility is to determine the charge density ...

  7. Spontaneous fission of superheavy nuclei

    Indian Academy of Sciences (India)

    collaborators [1,2]. The importance of deformed valleys in the potential energy surfaces. (PES) is that they provide the most favoured fission channels for the decay of superheavy nuclei. For the dynamics study, one has to introduce the influence of mass tensor. We use the results from pairing calculations for the occupation ...

  8. Cavitation Nuclei: Experiments and Theory

    DEFF Research Database (Denmark)

    Mørch, Knud Aage

    2009-01-01

    us a chance to reflect on the character of the unknown parameters. In this way non-concordant experimental results may hold the key to the development of better theories - and to new experiments for the testing of their validity. Cavitation and cavitation nuclei are phenomena of that character....

  9. Weak pion production from nuclei

    Indian Academy of Sciences (India)

    Abstract. The charged current pion production induced by neutrinos in 12C, 16O and 56Fe nuclei has been studied. The calculations have been done for the coherent as well as the incoherent processes assuming dominance and takes into account the effect of Pauli blocking, Fermi motion and the renormalization of in ...

  10. Percolation and multifragmentation of nuclei

    International Nuclear Information System (INIS)

    Shmakov, S.Yu.; Uzhinskij, V.V.

    1989-01-01

    A method to build the 'cold' nuclei as percolation clusters is suggested. Within the framework of definite assumptions of the character of nucleon-nucleon couplings breaking resulting from the nuclear reactions as description of the multifragmentation process in the hadron-nucleus and nucleus-nucleus reactions at high energies is obtained. 19 refs.; 6 figs

  11. Spontaneous fission of superheavy nuclei

    Indian Academy of Sciences (India)

    2015-08-02

    Aug 2, 2015 ... ... nuclear configurations typical for fission processes. The deformed two-centre shell model is used to obtain single-particle energy levels for the transition region of two partially overlapped daughter and emitted fragment nuclei. The macroscopic part is obtained using the Yukawa-plus-exponential potential.

  12. Proton scattering from unstable nuclei

    Indian Academy of Sciences (India)

    Abstract. Recent improvements in the intensities and optical qualities of radioactive beams have made possible the study of elastic and inelastic proton scattering on unstable nuclei. The design and performances of an innovative silicon strip detector array devoted to such experiments are described. The quality of the data ...

  13. Nuclear astrophysics of light nuclei

    DEFF Research Database (Denmark)

    Fynbo, Hans Otto Uldall

    2013-01-01

    A review of nuclear astrophysics of light nuclei using radioactive beams or techniques developed for radioactive beams is given. We discuss Big Bang nucleosynthesis, with special focus on the lithium problem, aspects of neutrino-physics, helium-burning and finally selected examples of studies...

  14. Unintegrated parton distributions in nuclei

    Science.gov (United States)

    de Oliveira, E. G.; Martin, A. D.; Navarra, F. S.; Ryskin, M. G.

    2013-09-01

    We study how unintegrated parton distributions in nuclei can be calculated from the corresponding integrated partons using the EPS09 parametrization. The role of nuclear effects is presented in terms of the ratio R A = uPDF A / A·PDF N for both large and small x domains.

  15. Weak pion production from nuclei

    Indian Academy of Sciences (India)

    The pion production processes from nucleons and nuclei at intermediate energies are important tools to study the hadronic structure. The dynamic models of the hadronic structure are used to calculate the various nucleon and transition form factors which are tested by using the experimental data on photo, electro and.

  16. Recent Precision Experiments with Exotic Nuclei Produced with Uranium Projectiles and Experimental Prospects at Fair

    Directory of Open Access Journals (Sweden)

    Geissel H.

    2014-03-01

    Full Text Available Precision experiments with relativistic fragments separated in-flight require special experimentalmethods to overcome the inherent large emittance from the creation in nuclear reactions and atomic interactions in matter. At GSI relativistic exotic nuclei have been produced via uranium projectile fragmentation and fission and investigated with the inflight separator FRS directly, or in combination with either the storage-cooler ring ESR or the FRS Ion Catcher. 1000 A·MeV 238U ions were used to create 60 new neutron-rich isotopes separated and identified with the FRS to measure their production cross sections. In another experimental campaign the fragments were separated in flight and injected into the storage-cooler ring ESR for accurate mass and lifetime measurements. In these experimentswe have obtained accurate new mass values analyzed via a novel method which has reduced the systematic errors for both Schottky Mass Spectrometry (SMS and for Isochronous Mass Spectrometry (IMS. Pioneering experiments have been carried out with the FRS Ion Catcher consisting of three experimental components, the dispersive magnetic system of the FRS with a monoenergetic and a homogeneous degrader, a cryogenic stopping cell filled with pure helium and a multiple-reflection time-of flight mass separator. The FRS Ion Catcher enables high precision spectroscopy experiments with eV to keV exotic nuclides. Results from these different FRS experiments are presented in this overview together with prospects for the next-generation facility Super-FRS. The novel features of the Super-FRS compared with the present FRS will be discussed in addition.

  17. Nuclear treasure island [superheavy nuclei

    CERN Document Server

    CERN. Geneva

    1999-01-01

    Summary form only given. Soon after the experiments at Dubna, which synthesized element 114 and made the first footprints on the beach of the "island of nuclear stability", two new superheavy elements have been discovered at the Lawrence Berkeley National Laboratory. Element 118 and its immediate decay product, element 116, were manufactured at Berkeley's 88 inch cyclotron by fusing targets of lead-208 with an intense beam of 449 MeV krypton-86 ions. Although both new nuclei almost instantly decay into lighter ones, the decay sequence is consistent with theories that have long predicted the island of stability for nuclei with approximately 114 protons and 184 neutrons. Theorist Robert Smolanczuk, visiting from the Soltan Institute for Nuclear Studies in Poland, had calculated that this reaction should have particularly favourable production rates. Now that this route has been signposted, similar reactions could be possible: new elements and isotopes, tests of nuclear stability and mass models, and a new under...

  18. Cooper pairs in atomic nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Pittel, S. [Bartol Research Institute and Department of Physics and Astronomy, University of Delaware, Newark, 19716 Delaware (United States); Dussel, G. G. [Departamento de Fisica J.J. Giambiagi, Universidad de Buenos Aires, 1428 Buenos Aires (Argentina); Dukelsky, J.; Sarriguren, P. [Instituto de Estructura de la Materia, CSIC, Serrano 123, 28006 Madrid (Spain)

    2008-12-15

    We describe recent efforts to study Cooper pairs in atomic nuclei. We consider a self-consistent Hartree Fock mean field for the even Sm isotopes and compare results based on three treatments of pairing correlations: a BCS treatment, a number-projected BCS treatment and an exact treatment using the Richardson Ansatz. Significant differences are seen in the pairing correlation energies. Furthermore, because it does not average over the properties of the fermion pairs, the Richardson solution permits a more meaningful definition of the Cooper wave function and of the fraction of pairs that are collective. Our results confirm that only a few pairs near the Fermi surface in realistic atomic nuclei are collective. (Author)

  19. Relativistic description of deformed nuclei

    International Nuclear Information System (INIS)

    Price, C.E.

    1988-01-01

    The author has shown that relativistic Hartree calculations using parameters that have been fit to the properties of nuclear matter can provide a good description of both spherical and axially deformed nuclei. The quantitative agreement with experiment is equivalent to that which was obtained in non-relativistic calculations using Skyrme interactions. The equilibrium deformation is strongly correlated with the size of the spin-orbit splitting, and that parameter sets which give roughly the correct value for this splitting provide the best agreement with the quadrupole moments in the s-d shell. Finally, for closed shell +/- 1 nuclei, it was shown that the self-consistent calculations are able to reproduce the experimental magnetic moments. This was not possible in relativistic calculations which include only the effects of the valence orbital

  20. Multiple phonon excitation in nuclei

    International Nuclear Information System (INIS)

    Chomaz, Ph.; Frascaria, N.

    1994-01-01

    The studies of multiphonon excitations in nuclei are reviewed both from the theoretical and experimental points of view. The presence of giant resonances in nuclei is described in the framework of macroscopic and microscopic models and the relative merits of different probes to excite such states are illustrated. The existence of giant resonances built on excited states is stressed. An exhaustive description of the theoretical estimates of the properties of the multiphonon states is presented. The theory predicts that such multiple collective excitations should closely follow a harmonic pattern. Recent experimental results on the double giant dipole resonance using the (π + π - ) double charge exchange reaction are shown. The status of the search for isoscalar multiphonon excitations by means of the strong nuclear potential produced by heavy ions is presented. Conclusions are drawn and new prospects are discussed. (authors) 293 refs., 67 figs., 8 tabs

  1. Spectroscopy of heavy fissionable nuclei

    Indian Academy of Sciences (India)

    2015-08-05

    Aug 5, 2015 ... A comparison of aligned angular momentum in these nuclei over the range of observed frequencies (up to ¯hω ≈ 0.25 MeV) reveals a possible, small but signifi- cant contribution from j15/2 neutrons in 249Cm, as evidenced from the higher degree of alignment compared to 247Cm over the observed range ...

  2. Density functional theory of nuclei

    International Nuclear Information System (INIS)

    Terasaki, Jun

    2008-01-01

    The density functional theory of nuclei has come to draw attention of scientists in the field of nuclear structure because the theory is expected to provide reliable numerical data in wide range on the nuclear chart. This article is organized to present an overview of the theory to the people engaged in the theory of other fields as well as those people in the nuclear physics experiments. At first, the outline of the density functional theory widely used in the electronic systems (condensed matter, atoms, and molecules) was described starting from the Kohn-Sham equation derived on the variational principle. Then the theory used in the field of nuclear physics was presented. Hartree-Fock and Hartree-Fock-Bogolyubov approximation by using Skyrme interaction was explained. Comparison of the results of calculations and experiments of binding energies and ground state mean square charge radii of some magic number nuclei were shown. The similarity and dissimilarity between the two streams were summarized. Finally the activities of the international project of Universal Nuclear Energy Density Functional (UNEDF) which was started recently lead by US scientist was reported. This project is programmed for five years. One of the applications of the project is the calculation of the neutron capture cross section of nuclei on the r-process, which is absolutely necessary for the nucleosynthesis research. (S. Funahashi)

  3. Thermodynamical description of excited nuclei

    International Nuclear Information System (INIS)

    Bonche, P.

    1989-01-01

    In heavy ion collisions it has been possible to obtain composite systems at rather high excitation energies corresponding to temperatures of several MeV. The theoretical studies of these systems are based on concepts borrowed from thermodynamics or statistical physics, such as the temperature. In these lectures, we present the concepts of statistical physics which are involved in the physics of heavy ion as they are produced nowadays in the laboratory and also during the final stage of a supernova collapse. We do not attempt to describe the reaction mechanisms which yield such nuclear systems nor their decay by evaporation or fragmentation. We shall only study their static properties. The content of these lectures is organized in four main sections. The first one gives the basic features of statistical physics and thermodynamics necessary to understand quantum mechanics at finite temperature. In the second one, we present a study of the liquid-gas phase transition in nuclear physics. A phenomenological approach of the stability of hot nuclei follows. The microscopic point of view is proposed in the third part. Starting from the basic concepts derived in the first part, it provides a description of excited or hot nuclei which confirms the qualitative results of the second part. Furthermore it gives a full description of most properties of these nuclei as a function of temperature. Finally in the last part, a microscopic derivation of the equation of state of nuclear matter is proposed to study the collapse of a supernova core

  4. Clustering in light nuclei and their effects on fusion and pre - equilibrium processes.

    Science.gov (United States)

    Gramegna, Fabiana; Cicerchia, Magda; Fabris, Daniela; Marchi, Tommaso; Cinausero, Marco; Degerlier, Meltem; Mabiala, Justin; Mantovani, Giorgia; Morelli, Luca; D'Agostino, Michela; Bruno, Mauro; Barlini, Sandro; Bini, Maurizio; Pasquali, Gabriele; Piantelli, Silvia; Casini, Giovanni; Pastore, Giuseppe; Gruyer, Diego; Ottanelli, Pietro; Valdré, Simone; Gelli, Nicla; Olmi, Alessandro; Poggi, Giacomo; Vardaci, Emanuele; Lombardo, Ivano; Dell'Aquila, Daniele; Leoni, Silvia; Cieplicka-Orynczak, Natalya; Fornal, Bogdan; Mengoni, Daniele; Collazuol, Gianmaria; Caciolli, Antonio; Colonna, Maria; Ono, Akira; Baiocco, Giorgio

    2017-11-01

    The study of nuclear cluster states bound by valence neutrons is a field of recent large interest. In particular, it is important to study the pre-formation of α-clusters in α-conjugate nuclei and the dynamical condensation of clusters during nuclear reactions [1-5]. The NUCL-EX collaboration has recently initiated an experimental campaign of exclusive measurements of fusion-evaporation reactions with light nuclei as interacting partners. In collisions involving light systems, the low expected multiplicity of fragments increases the probability of achieving a quasi-complete reconstruction of the event. In particular the formation and decay modes of an excited 24Mg system have been studied through two different reactions, 12C (95 MeV)+ 12C and 14N (80.7 MeV)+ 10B, which have been used to produce fused systems with nearly the same mass and excitation energy ( 60 MeV). In particular, even the de-excitation of the Hoyle state in 12C have been studied, both in peripheral (projectiles de-excitation) and in central collisions (six α-particles channel). Moreover, a research campaign studying pre-equilibrium emission of light charged particles and cluster properties of light and medium-mass nuclei has been carried out. For this purpose, a comparative study of the three nuclear systems 18O+28Si, 16O+30Si and 19F+27Al has been recently studied using the GARFIELD+RCo 4π setup [6]. The experimental data are compared with the predictions of simulated events generated with the statistical models (GEMINI++ and HFl) and through dynamical models like Stochastic Mean Field (SMF) and Antisymmetrized Molecular Dynamics (AMD) and filtered with a software replica of our apparatus in order to take into account the experimental conditions.

  5. Clustering in light nuclei and their effects on fusion and pre – equilibrium processes.

    Directory of Open Access Journals (Sweden)

    Gramegna Fabiana

    2017-01-01

    Full Text Available The study of nuclear cluster states bound by valence neutrons is a field of recent large interest. In particular, it is important to study the pre-formation of α-clusters in α-conjugate nuclei and the dynamical condensation of clusters during nuclear reactions [1–5]. The NUCL–EX collaboration has recently initiated an experimental campaign of exclusive measurements of fusion–evaporation reactions with light nuclei as interacting partners. In collisions involving light systems, the low expected multiplicity of fragments increases the probability of achieving a quasi-complete reconstruction of the event. In particular the formation and decay modes of an excited 24Mg system have been studied through two different reactions, 12C (95 MeV+ 12C and 14N (80.7 MeV+ 10B, which have been used to produce fused systems with nearly the same mass and excitation energy (~60 MeV. In particular, even the de-excitation of the Hoyle state in 12C have been studied, both in peripheral (projectiles de-excitation and in central collisions (six α-particles channel. Moreover, a research campaign studying pre-equilibrium emission of light charged particles and cluster properties of light and medium-mass nuclei has been carried out. For this purpose, a comparative study of the three nuclear systems 18O+28Si, 16O+30Si and 19F+27Al has been recently studied using the GARFIELD+RCo 4π setup [6]. The experimental data are compared with the predictions of simulated events generated with the statistical models (GEMINI++ and HFl and through dynamical models like Stochastic Mean Field (SMF and Antisymmetrized Molecular Dynamics (AMD and filtered with a software replica of our apparatus in order to take into account the experimental conditions.

  6. The astrophysical r-process and its dependence on properties of nuclei far from stability: Beta strength functions and neutron capture rates

    International Nuclear Information System (INIS)

    Klapdor, H.V.; Metzinger, J.; Oda, T.; Thielemann, F.K.; Hillebrandt, W.

    1981-01-01

    The question of the astrophysical site of the rapid neutron capture (r-) process which is believed to be responsible for the production of the heavy elements in the universe has been a problem in astrophysics for more than two decades. The solution of this problem is not only dependent on the development of realistic astrophysical supernova models, i.e. correct treatment of the hydrodynamics of gravitational collapse and supernova explosion and the equation of state of hot and dense matter, but is shown in this paper to be very sensitive also to 'standard' nuclear physics properties of nuclei far from stability such as beta decay properties and neutron capture rates. For both of the latter, strongly oversimplifying assumptions, not applying the development in nuclear physics during the last decade, have been made in almost all r-process calculations performed up to now. A critical discussion of the state of the art of such calculations seems therefore to be indicated. In this paper procedures are described which allow one to obtain: 1) β-decay properties (decay rates, β-delayed neutron emissions and fission rates); 2) neutron capture rates for neutron-rich nuclei considerably improved over what has been used up to now. The beta strength functions are calculated for approx. equal to6000 nuclei between beta stability line and neutron drip line. By hydrodynamical supernova explosion calculations using realistic stellar models it is shown that as a consequence of the improved β-rates explosive He burning is a convincing alternative site to the 'classical' r-process whose existence still is questionable. The new β-rates will be important also for the investigation of further astrophysical sites producing heavy elements such as the r(n)-processes in explosive C or Ne burning. (orig.)

  7. 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

  8. Microscopic structure for light nuclei

    International Nuclear Information System (INIS)

    Sharma, V.K.

    1995-01-01

    The microscopic structure for light nuclei e.g. 4 He, 7 Li and 8 Be is considered in the frame work of the generator coordinate method (GCM). The physical interpretation of our GCM is also discussed. The GC amplitudes are used to calculate the various properties like charge and magnetic RMS radii, form factors, electromagnetic moments, astrophysical S-factor, Bremsstrahlung weighted cross sections, relative wavefunctions and vertex functions etc. All the calculated quantities agree well with the values determined experimentally. (author). 30 refs., 10 figs., 2 tabs

  9. Nucleon transfer between heavy nuclei

    International Nuclear Information System (INIS)

    Von Oertzen, W.

    1984-02-01

    Nucleon transfer reactions between heavy nuclei are characterized by the classical behaviour of the scattering orbits. Thus semiclassical concepts are well suited for the description of these reactions. In the present contribution the characteristics of single and multinucleon transfer reactions at energies below and above the Coulomb barrier are shown for systems like Sn+Sn, Xe+U and Ni+Pb. The role of the pairing interaction in the transfer of nucleon pairs is illustrated. For strong transitions the coupling of channels and the absorption into more complicated channels is taken into account in a coupled channels calculation

  10. Quarks in hadrons and nuclei

    International Nuclear Information System (INIS)

    Close, F.E.

    1988-01-01

    The paper concerns some of the ideas underlying quarks and their interactions, the way that quarks build up hadrons, and the extent to which the QCD theory can be applied to phenomena involving nuclei. The article is part of the Proceedings of the International School of Nuclear Physics, Erice, 1987. A description is given of quarks and multiplets. Colour is discussed with respect to: evidence for colour, a non abelian Su(3) theory, the pauli principle at work in hadrons, and spin flavour correlations and magnetic moments. Colour, gluons and the inter quark potential are also examined. (UK)

  11. Microscopic properties of superdeformed nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Karlsson, Lennart B

    1999-04-01

    Many high spin rotational bands in superdeformed nuclei have been found in the A 140 - 150 region, but so far no linking transitions to known normal-deformed states have been found in these nuclei. Therefore, configuration and spin assignments have to be based on indirect spectroscopic information. Identical bands were first discovered in this region of superdeformed states. At present, some identical bands have also been found at normal deformation, but such bands are more common at superdeformation. Recently lifetime measurements have given relative quadrupole moments with high accuracy. Spectroscopic quantities are calculated using the configuration constrained cranked Nilsson-Strutinsky model with the modified oscillator potential. In a statistical study the occurrence of identical bands is tested. Comparing superdeformed and normal deformed nuclei, the higher possibility for identical bands at superdeformation is understood from calculated reduced widths of the E{sub {gamma}} and J{sup (2)} distributions. The importance of high-N orbitals for identical bands is also discussed. Additivity of electric quadrupole moment contributions in the superdeformed A - 150 region is discussed with the nucleus {sup 152}Dy as a `core`. In analytic harmonic oscillator calculations, the effective electric quadrupole moment q{sub eff}, i.e. the change in the total quadrupole moment caused by the added particle, is expressed as a simple function of the single-particle mass, quadrupole moment q{sub {nu}}. Also in realistic calculations, simple relations between q{sub eff} and q{sub {nu}} can be used to estimate the total electric quadrupole moment, e.g. for the nucleus {sup 142}Sm, by adding the effect of 10 holes, to the total electric quadrupole moment of {sup 152}Dy. Furthermore, tools are given for estimating the quadrupole moment for possible configurations in the superdeformed A - 150 region. For the superdeformed region around {sup 143}Eu, configuration and spin assignments

  12. Barriers in the energy of deformed nuclei

    Directory of Open Access Journals (Sweden)

    V. Yu. Denisov

    2014-06-01

    Full Text Available Interaction energy between two nuclei considering to their deformations is studied. Coulomb and nuclear in-teraction energies, as well as the deformation energies of both nuclei, are taken into account at evaluation of the interaction energy. It is shown that the barrier related to the interaction energy of two nuclei depends on the de-formations and the height of the minimal barrier is evaluated. It is obtained that the heavier nucleus-nucleus sys-tems have large deformation values at the lowest barrier. The difference between the barrier between spherical nuclei and the lowest barrier between deformed nuclei increases with the mass and the charge of the interacting nuclei.

  13. 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

  14. 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

  15. Are there multiquark bags in nuclei

    International Nuclear Information System (INIS)

    Kondratyuk, L.A.; Scmatkov, M.Zh.

    1983-01-01

    Arguments are presented favouring the idea that multiquark bags do eXist in nuclei. Such hypothesis makes possible to reveal the relationship among three different scopes of phenomena: deep inelastic scattering of leptons by nUclei, large q 2 (where q 2 is a square of momentum transfer) behaviour of the form factors of light nuclei and yield of cumulative proton.s

  16. Nuclei quadrupole coupling constants in diatomic molecule

    International Nuclear Information System (INIS)

    Ivanov, A.I.; Rebane, T.K.

    1993-01-01

    An approximate relationship between the constants of quadrupole interaction of nuclei in a two-atom molecule is found. It enabled to establish proportionality of oscillatory-rotation corrections to these constants for both nuclei in the molecule. Similar results were obtained for the factors of electrical dipole-quadrupole screening of nuclei. Applicability of these relationships is proven by the example of lithium deuteride molecule. 4 refs., 1 tab

  17. Deformation effect on spectral statistics of nuclei

    Science.gov (United States)

    Sabri, H.; Jalili Majarshin, A.

    2018-02-01

    In this study, we tried to get significant relations between the spectral statistics of atomic nuclei and their different degrees of deformations. To this aim, the empirical energy levels of 109 even-even nuclei in the 22 ≤ A ≤ 196 mass region are classified as their experimental and calculated quadrupole, octupole, hexadecapole and hexacontatetrapole deformations values and analyzed by random matrix theory. Our results show an obvious relation between the regularity of nuclei and strong quadrupole, hexadecapole and hexacontatetrapole deformations and but for nuclei that their octupole deformations are nonzero, we have observed a GOE-like statistics.

  18. The asymptotic hadron spectrum, anti-nuclei, hyper-nuclei and quark phase

    International Nuclear Information System (INIS)

    Glendenning, N.K.

    1978-01-01

    The only hope of determining the hadronic spectrum in the high mass region is through a study of matter produced in very high energy nuclear collisions. Along the way, exotic nuclei, i.e., anti-nuclei and hyper-nuclei may be produced in appreciable numbers, and the detection of a quark phase may be possible. (orig.) [de

  19. Development of the ISOLDE Decay Station and γ spectroscopic studies of exotic nuclei near the N=20 “Island of Inversion”

    CERN Document Server

    Lica, Razvan; Garcia Borge, Maria Jose; Marginean, Nicolae Marius

    2017-10-03

    The main topic of my PhD Thesis is related to nuclear structure studies of neutron-rich nuclei following the beta-decay of 34Mg isotopes produced at the ISOLDE facility of CERN and measured using one of the newest permanent experimental setups, the ISOLDE Decay Station (IDS). I will also describe this setup and some of developments I contributed to during the three years spent as a PhD Student at CERN. This Thesis is divided into 6 chapters: The first chapter contains a description of the radioactive ion-beam production techniques with an emphasis on the ISOL technique and an overview of the capabilities of the ISOLDE facility of CERN. The second chapter is dedicated to the IDS setup, its capabilities and development since the first experimental campaign in 2014. The GEANT4 simulations of IDS are the subject in the third chapter, which cover mainly the HPGe detectors, the core detection system of IDS, and a possible improvement related to reducing the large background present in the high energy region of the ...

  20. Decay properties of nuclei close to Z = 108 and N = 162

    Energy Technology Data Exchange (ETDEWEB)

    Dvorak, Jan

    2007-07-12

    observed decay properties provide strong indications for enhanced nuclear stability in this area of the heaviest known elements and provide an important reference point for theoretical models. The measurement of the production cross sections at five beam energies allowed the evaluation of excitation functions for the 3-5n evaporation channels at the few picobarn level. Experimental data indicate a surprising cross section enhancement at sub-barrier energies due to the deformation of the target nucleus. This opens prospects for the search for the 3n evaporation channel products in nuclear reactions with actinide targets, induced with light neutron rich projectiles. (orig.)

  1. 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)

  2. Thermodynamics of pairing phase transition in nuclei

    International Nuclear Information System (INIS)

    Karim, Afaque; Ahmad, Shakeb

    2014-01-01

    The pairing gaps, pairing energy, heat capacity and entropy are calculated within BCS (Bardeen- Cooper-Schrieffer) based quasi particle approach, including thermal fluctuations on pairing field within pairing model for all nuclei (light, medium, heavy and super heavy nuclei). Quasi particles approach in BCS theory was introduced and reformulated to study various properties. For thermodynamic behavior of nuclei at finite temperatures, the anomalous averages of creation and annihilation operators are introduced. It is solved self consistently at finite temperatures to obtain BCS Hamiltonian. After doing unitary transformation, we obtained the Hamiltonian in the diagonal form. Thus, one gets temperature dependence gap parameter and pairing energy for nuclei. Moreover, the energy at finite temperatures is the sum of the condensation energy and the thermal energy of fermionic quasi particles. With the help of BCS Hamiltonian, specific heat, entropy and free energy are calculated for different nuclei. In this paper the gap parameter occupation number and pairing energy as a function of temperature which is important for all the light, medium, heavy and super heavy nuclei is calculated. Moreover, the various thermo dynamical quantities like specific heat, entropy and free energy is also obtained for different nuclei. Thus, the thermodynamics of pairing phase transition in nuclei is studied

  3. RFP for the Comet Nuclei Tour (CONTOUR)

    DEFF Research Database (Denmark)

    Jørgensen, John Leif; Madsen, Peter Buch; Betto, Maurizio

    1999-01-01

    This document describes the ASC Star Tracker (performance, functionality, requirements etc.) to The Johns Hopkins University - Applied Physics Laboratory for their Comet Nuclei TOUR (CONTOUR) Program.......This document describes the ASC Star Tracker (performance, functionality, requirements etc.) to The Johns Hopkins University - Applied Physics Laboratory for their Comet Nuclei TOUR (CONTOUR) Program....

  4. Partial Dynamical Symmetry in Deformed Nuclei

    International Nuclear Information System (INIS)

    Leviatan, A.

    1996-01-01

    We discuss the notion of partial dynamical symmetry in relation to nuclear spectroscopy. Explicit forms of Hamiltonians with partial SU(3) symmetry are presented in the framework of the interacting boson model of nuclei. An analysis of the resulting spectrum and electromagnetic transitions demonstrates the relevance of such partial symmetry to the spectroscopy of axially deformed nuclei. copyright 1996 The American Physical Society

  5. Partial Dynamical Symmetry in Deformed Nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Leviatan, A. [Racah Institute of Physics, The Hebrew University, Jerusalem 91904 (Israel)

    1996-07-01

    We discuss the notion of partial dynamical symmetry in relation to nuclear spectroscopy. Explicit forms of Hamiltonians with partial SU(3) symmetry are presented in the framework of the interacting boson model of nuclei. An analysis of the resulting spectrum and electromagnetic transitions demonstrates the relevance of such partial symmetry to the spectroscopy of axially deformed nuclei. {copyright} {ital 1996 The American Physical Society.}

  6. 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

  7. SPECTROSCOPY OF MEDIUM-MASS HYPERNUCLEAR PRODUCTION

    Czech Academy of Sciences Publication Activity Database

    Motoba, T.; Bydžovský, Petr; Sotona, Miloslav; Itonaga, K.; Ogawa, K.; Hashimoto, O.

    2010-01-01

    Roč. 19, č. 12 (2010), s. 2470-2479 ISSN 0218-3013. [Sendai International Conference on Strangeness in Nuclear and Hadronic Systems. Sendai, 15.12.2008-18.12.2008] Institutional research plan: CEZ:AV0Z10480505 Keywords : Hypernuclear photoproduction * DWIA * unnatural parity states Subject RIV: BE - Theoretical Physics Impact factor: 0.695, year: 2010

  8. A new spin on nuclei

    International Nuclear Information System (INIS)

    Clark, R.; Wadsworth, B.

    1998-01-01

    Magnetic rotation is a new phenomenon that is forcing physicists to rethink their understanding of what goes on inside the nucleus The rotation of quantum objects has a long and distinguished history in physics. In 1912 the Danish scientist Niels Bjerrum was the first to recognize that the rotation of molecules is quantized. In 1938 Edward Teller and John Wheeler observed similar features in the spectra of excited nuclei, and suggested that this was caused by the nucleus rotating. But a more complete explanation had to wait until 1951, when Aage Bohr (the son of Niels) pointed out that rotation was a consequence of the nucleus deforming from its spherical shape. We owe much of our current understanding of nuclear rotation to the work of Bohr and Ben Mottelson, who shared the 1975 Nobel Prize for Physics with James Rainwater for developing a model of the nucleus that combined the individual and collective motions of the neutrons and protons inside the nucleus. What makes it possible for a nucleus to rotate? Quantum mechanically, a perfect sphere cannot rotate because it appears the same when viewed from any direction and there is no point of reference against which its change in position can be detected. To see the rotation the spherical symmetry must be broken to allow an orientation in space to be defined. For example, a diatomic molecule, which has a dumbbell shape, can rotate about the two axes perpendicular to its axis of symmetry. A quantum mechanical treatment of a diatomic molecule leads to a very simple relationship between rotational energy, E, and angular momentum. This energy is found to be proportional to J(J + 1), where J is the angular momentum quantum number. The molecule also has a magnetic moment that is proportional to J. These concepts can be applied to the atomic nucleus. If the distribution of mass and/or charge inside the nucleus becomes non-spherical then the nucleus will be able to rotate. The rotation is termed ''collective'' because many

  9. Ice Nuclei from Birch Trees

    Science.gov (United States)

    Felgitsch, Laura; Seifried, Teresa; Winkler, Philipp; Schmale, David, III; Grothe, Hinrich

    2017-04-01

    While the importance of heterogeneous ice nucleation in the atmosphere is known, we still know very little about the substances triggering these freezing events. Recent findings support the theory that biological ice nuclei (IN) exhibit the ability to play an important role in these processes. Huffman et al. (2013) showed a burst of biological IN over woodlands triggered by rain events. Birch pollen are known to release a high number of efficient IN if incubated in water (Pummer et al. 2012). Therefore birches are of interest in our research on this topic. Plants native to the timberline, such as birch trees, have to cope with very cold climatic conditions, rendering freezing avoidance impossible. These plants trigger freezing in their extracellular spaces to control the freezing process and avoid intracellular freezing, which would have lethal consequences. The plants hereby try to freeze at a temperature well above homogeneous freezing temperatures but still at temperatures low enough to not be effected by brief night frosts. To achieve this, IN are an important tool. The specific objective of our work was to study the potential sources and distribution of IN in birch trees. We collected leaves, fruit, bark, and trunk cores from a series of mature birch trees in Tyrol, Austria at different altitudes and sampling sites. We also collected samples from a birch tree in an urban park in Vienna, Austria. Our data show a sampling site dependence and the distribution of IN throughout the tree. Our data suggest that leaves, bark, and wood of birch can function as a source of IN, which are easily extracted with water. The IN are therefore not restricted to pollen. Hence, the amount of IN, which can be released from birch trees, is tremendous and has been underrated so far. Future work aims to elucidate the nature, contribution, and potential ecological roles of IN from birch trees in different habitats. Huffman, J.A., Prenni, A.J., DeMott, P.J., Pöhlker, C., Mason, R

  10. Particles and nuclei, letters, in Russian, pt.3

    CERN Document Server

    2002-01-01

    The present collection of letters from JINR, Dubna, contains eight separate records on the role of the complanar emission of particles in nuclear interaction for E sub 0 >10 sup 1 sup 6 eV detected in the stratosphere, sup 1 sup 0 B nucleus fragment yields, nuclear teleportation (proposal for an experiment), invisible 'glue' bosons in model field theory, calculation of the ionization differential effective cross sections in fast ion-atom collisions, interactions of ultracold neutrons near surface of solids, g factors as a probe for high-spin structure of neutron-rich Dy isotopes, search for periodicities in experimental data by the autoregressive model methods

  11. Symmetry and Phase Transitions in Nuclei

    International Nuclear Information System (INIS)

    Iachello, F.

    2009-01-01

    Phase transitions in nuclei have received considerable attention in recent years, especially after the discovery that, contrary to expectations, systems at the critical point of a phase transition display a simple structure. In this talk, quantum phase transitions (QPT), i.e. phase transitions that occur as a function of a coupling constant that appears in the quantum Hamiltonian, H, describing the system, will be reviewed and experimental evidence for their occurrence in nuclei will be presented. The phase transitions discussed in the talk will be shape phase transitions. Different shapes have different symmetries, classified by the dynamic symmetries of the Interacting Boson Model, U(5), SU(3) and SO(6). Very recently, the concept of Quantum Phase Transitions has been extended to Excited State Quantum Phase Transitions (ESQPT). This extension will be discussed and some evidence for incipient ESQPT in nuclei will be presented. Systems at the critical point of a phase transition are called 'critical systems'. Approximate analytic formulas for energy spectra and other properties of 'critical nuclei', in particular for nuclei at the critical point of the second order U(5)-SO(6) transition, called E(5), and along the line of first order U(5)-SU(3) transitions, called X(5), will be presented. Experimental evidence for 'critical nuclei' will be also shown. Finally, the microscopic derivation of shape phase transitions in nuclei within the framework of density functional methods will be briefly discussed.(author)

  12. Evolution of planetary nebula nuclei

    International Nuclear Information System (INIS)

    Shaw, R.A.

    1985-01-01

    The evolution of planetary nebula nuclei (PNNs) is examined with the aid of the most recent available stellar evolution calculations and new observations of these objects. Their expected distribution in the log L-log T plane is calculated based upon the stellar evolutionary models of Paczynski, Schoenberner and Iben, the initial mass function derived by Miller and Scalo, and various assumptions concerning mass loss during post-main sequence evolution. The distribution is found to be insensitive both to the assumed range of main-sequence progenitor mass and to reasonable variations in the age and the star forming history of the galactic disk. Rather, the distribution is determined by the strong dependence of the rate of stellar evolution upon core mass, the steepness of the initial mass function, and to a lesser extent the finite lifetime of an observable planetary nebula. The theoretical distributions are rather different than any of those inferred from earlier observations. Possible observational selection effects that may be responsible are examined, as well as the intrinsic uncertainties associated with the theoretical model predictions. An extensive photometric and smaller photographic survey of southern hemisphere planetary nebulae (PNs) is presented

  13. Clusters in Nuclei. Vol. 2

    International Nuclear Information System (INIS)

    Beck, Christian

    2012-01-01

    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 second volume follows the successful Lect. Notes Phys. 818 (Vol.1), and comprises six extensive lectures covering the following topics: - Microscopic cluster models - Neutron halo and break-up reactions - Break-up reaction models for two- and three-cluster projectiles - Clustering effects within the di-nuclear model - Nuclear alpha-particle condensates - Clusters in nuclei: experimental perspectives By promoting new ideas and developments while retaining a pedagogical style of presentation throughout, these lectures will serve as both a reference and an advanced teaching manual for future courses and schools in the fields of nuclear physics and nuclear astrophysics. (orig.)

  14. Hot nuclei: high temperatures, high angular momenta

    International Nuclear Information System (INIS)

    Guerreau, D.

    1991-01-01

    A review is made of the present status concerning the production of hot nuclei above 5 MeV temperature, concentrating mainly on the possible experimental evidences for the attainment of a critical temperature, on the existence of dynamical limitations to the energy deposition and on the experimental signatures for the formation of hot spinning nuclei. The data strongly suggest a nuclear disassembly in collisions involving very heavy ions at moderate incident velocities. Furthermore, hot nuclei seem to be quite stable against rotation on a short time scale. (author) 26 refs.; 12 figs

  15. Systematics of triaxial moment of inertia and deformation parameters (β, γ) in even-even nuclei of mass region A = 90-120

    International Nuclear Information System (INIS)

    Singh, Yuvraj; Gupta, D.K.; Singh, M.; Gupta, K.K.; Bihari, Chhail; Varshney, A.K.; Dhiman, S.K.

    2012-01-01

    The deformation parameter β and γ of the collective model of Bohr and Mottelson are basic descriptors of the nuclear equilibrium shape and structure. In recent past the sets of deformation parameters ((β, γ) have been extracted from both level energies and E2 transition rates in even Xe, Ba and Ce nuclei (A∼120-140) and Hf, W, Os, Pt and Hg nuclei (A∼160-200) using rigid triaxial rotor model of Davydov-Filippov (DF). Researcher have found that the values of β obtained separately from energy and transition rate (β e and β b respectively), though, are found almost equal in heavy mass region (A ∼160-200) but, not so in medium mass (A∼120-140) nuclei. This observation puts a question mark whether the ββ dependence of moment of inertia in hydrodynamic model is reliable. The purpose of the present work is to study a relatively lighter mass region (A∼90-120) where the gap between values of two sets of β may further increase. To improve the calculations for extracting β e , the use of Grodzins rule will be made along with uncertainties, since only through this rule the E2 1 + is related with β G (value of β for symmetric nucleus and evaluated using Grodzins rule)

  16. Parton distributions in nuclei: Quagma or quagmire

    Energy Technology Data Exchange (ETDEWEB)

    Close, F.E.

    1988-01-01

    The emerging information on the way quark, antiquark, and gluon distributions are modified in nuclei relative to free nucleons is reviewed. Particular emphasis is placed on Drell-Yan and /psi/ production on nuclei and caution against premature use of these as signals for quagma in heavy-ion collisions. If we are to identify the formation of quark-gluon plasma in heavy-ion collisions by changes in the production rates for /psi/ relative to Drell-Yan lepton pairs, then it is important that we first understand the ''intrinsic'' changes in parton distributions in nuclei relative to free nucleons. So, emerging knowledge on how quark, antiquark, and gluon distributions are modified in nuclei relative to free nucleons is reviewed, and the emerging theoretical concensus is briefly summarized.

  17. New vistas of exotic heavy nuclei

    International Nuclear Information System (INIS)

    Cocks, J.F.C.; Butler, P.A.

    1997-01-01

    We report studies of examples of reflection-asymmetric nuclei which are difficult to access using compound nucleus reactions. The most octupole deformed nuclei should be uranium isotopes with N ∼ 132; preliminary measurements of these very fissile nuclei suggest that they are within reach of current spectroscopic techniques. The octupole radium isotopes with N > 132 and radon isotopes are not accessible by reactions employing stable targets and beams; we have shown that multinucleon transfer reactions can populate these nuclei with sufficient yield for their structure to be determined. We report high spin studies in 218,220,222 Rn and 222,224,226 Ra which reveal upbending effects in this mass region for the first time and show that the electric dipole moment is constant with spin. (author)

  18. 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

  19. Nuclear Computational Low Energy Initiative (NUCLEI)

    Energy Technology Data Exchange (ETDEWEB)

    Reddy, Sanjay K. [University of Washington

    2017-08-14

    This is the final report for University of Washington for the NUCLEI SciDAC-3. The NUCLEI -project, as defined by the scope of work, will develop, implement and run codes for large-scale computations of many topics in low-energy nuclear physics. Physics to be studied include the properties of nuclei and nuclear decays, nuclear structure and reactions, and the properties of nuclear matter. The computational techniques to be used include Quantum Monte Carlo, Configuration Interaction, Coupled Cluster, and Density Functional methods. The research program will emphasize areas of high interest to current and possible future DOE nuclear physics facilities, including ATLAS and FRIB (nuclear structure and reactions, and nuclear astrophysics), TJNAF (neutron distributions in nuclei, few body systems, and electroweak processes), NIF (thermonuclear reactions), MAJORANA and FNPB (neutrino-less double-beta decay and physics beyond the Standard Model), and LANSCE (fission studies).

  20. Observation of spinodal decomposition in nuclei?

    International Nuclear Information System (INIS)

    Guarnera, A.; Colonna, M.; Chomaz, Ph.

    1996-01-01

    Multifragmentation in heavy ion collisions is investigated in the framework of mean-field theory, in order to gain information on the equation of state of nuclear matter. Spinodal decomposition in nuclei is studied. (K.A.)

  1. Infrared Observations of Cometary Dust and Nuclei

    Science.gov (United States)

    Lisse, Carey

    2004-01-01

    This bibliography lists citations for publications published under the grant. Subjects of the publications include cometary dust, instellar and interplanetary dust, comet nuclei and comae, Comet Hale-Bopp, infrared observations of comets, mass loss, and comet break-up.

  2. Critical-Point Structure in Finite Nuclei

    International Nuclear Information System (INIS)

    Leviatan, A.

    2006-01-01

    Properties of quantum shape-phase transitions in finite nuclei are considered in the framework of the interacting boson model. Special emphasis is paid to the dynamics at the critical-point of a general first-order phase transition

  3. Fusion of light exotic nuclei at near-barrier energies: Effect of ...

    Indian Academy of Sciences (India)

    Abstract. The effect of inelastic excitation of exotic light projectiles (proton- as well as neutron- rich) 17F and 11Be on fusion with heavy target has been studied at near-barrier energies. The cal- culations have been performed in the coupled channels approach where, in addition to the normal coupling of the ground state of ...

  4. 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)

  5. High energy particle interactions with nuclei

    International Nuclear Information System (INIS)

    Czyz, W.

    1978-01-01

    The recent interest in multiparticle production processes on nuclei was triggered by re-discovering their 'enigmatic simplicity' which has been known to cosmic ray physicists for over 20 years: the mean multiplicity and angular distributions of relativistic secondaries produced on nuclei do not differ markedly from what emerges from p-p collisions. The author considers how such reactions may provide a way of obtaining details of hadron structure. (Auth.)

  6. Nuclei far off the stability line

    International Nuclear Information System (INIS)

    Fenyes, T.

    1978-01-01

    Theoretical and experimental aspects of the formation of some ''exotic'' nuclei far off the stability line were reviewed in addition to the relevant results of research in this field. Results in beta- and gamma-ray spectroscopy, heavy-ion-spectroscopy, achievements in the fields of measuring the atomic mass, the moment, and the radius of the nuclei as well as some astronomical aspects were described. (Z.P.)

  7. Proton radioactivity from proton-rich nuclei

    International Nuclear Information System (INIS)

    Guzman, F.; Goncalves, M.; Tavares, O.A.P.; Duarte, S.B.; Garcia, F.; Rodriguez, O.

    1999-03-01

    Half-lives for proton emission from proton-rich nuclei have been calculated by using the effective liquid drop model of heavy-particle decay of nuclei. It is shown that this model is able to offer results or spontaneous proton-emission half-life-values in excellent agreement with the existing experimental data. Predictions of half-life-values for other possible proton-emission cases are present for null orbital angular momentum. (author)

  8. Oscillations of atomic nuclei in crystals

    OpenAIRE

    Vdovenkov, V. A.

    2002-01-01

    Oscillations of atomic nuclei in crystals are considered in this paper. It is shown that elastic nuclei oscillations relatively electron envelops (inherent, I-oscillations) and waves of such oscillations can exist in crystals at adiabatic condition. The types and energy quantums of I-oscillations for different atoms are determined. In this connection the adiabatic crystal model is offered. Each atom in the adiabatic model is submitted as I-oscillator whose stationary oscillatory terms are sho...

  9. Hot nuclei, limiting temperatures and excitation energies

    International Nuclear Information System (INIS)

    Peter, J.

    1986-09-01

    Hot fusion nuclei are produced in heavy ion collisions at intermediate energies (20-100 MeV/U). Information on the maximum excitation energy per nucleon -and temperatures- indicated by the experimental data is compared to the predictions of static and dynamical calculations. Temperatures around 5-6 MeV are reached and seem to be the limit of formation of thermally equilibrated fusion nuclei

  10. Thomas Fermi model of finite nuclei

    International Nuclear Information System (INIS)

    Boguta, J.; Rafelski, J.

    1977-01-01

    A relativistic Thomas-Fermi model of finite-nuclei is considered. The effective nuclear interaction is mediated by exchanges of isoscalar scalar and vector mesons. The authors include also a self-interaction of the scalar meson field and the Coulomb repulsion of the protons. The parameters of the model are constrained by the average nuclear properties. The Thomas-Fermi equations are solved numerically for finite, stable nuclei. The particular case of 208 82 Pb is considered in more detail. (Auth.)

  11. Parity and time reversal violation in nuclei

    International Nuclear Information System (INIS)

    Adelberger, E.G.; Washington Univ., Seattle

    1987-01-01

    The current status of investigations into parity (P) and time-reversal (T) violation in nuclei is considered. Nuclear P-violation is an expected consequence of the standard model. It has been observed in a wide variety of nuclei (from A=2, to A∼ 200) by using a wide variety of reactions (reactions induced by polarized neutrons and polarized protons, γ-decay, α-decay, and (α, γ) reactions)

  12. Major new sources of biological ice nuclei

    Science.gov (United States)

    Moffett, B. F.; Hill, T.; Henderson-Begg, S. K.

    2009-12-01

    Almost all research on biological ice nucleation has focussed on a limited number of bacteria. Here we characterise several major new sources of biogenic ice nuclei. These include mosses, hornworts, liverworts and cyanobacteria. Ice nucleation in the eukaryotic bryophytes appears to be ubiquitous. The temperature at which these organisms nucleate is that at which the difference in vapour pressure over ice and water is at or close to its maximum. At these temperatures (-8 to -18 degrees C) ice will grow at the expense of supercooled water. These organisms are dependent for their water on occult precipitation - fog, dew and cloudwater which by its nature is not collected in conventional rain gauges. Therefore we suggest that these organism produce ice nuclei as a water harvesting mechanism. Since the same mechanism would also drive the Bergeron-Findeisen process, and as moss is known to become airborne, these nuclei may have a role in the initiation of precipitation. The properties of these ice nuclei are very different from the well characterised bacterial nuclei. We will also present DNA sequence data showing that, although related, the proteins responsible are only very distantly related to the classical bacterial ice nuclei.

  13. Elastic magnetic form factors of exotic nuclei

    International Nuclear Information System (INIS)

    Dong Tiekuang; Guo Yanqing; Ren Zhongzhou

    2007-01-01

    How to identify the orbital of the valence nucleon(s) of exotic nuclei is an important problem. The elastic magnetic electron scattering is an excellent probe to determine the valence structure of odd-A nuclei. The relativistic mean-field theory has been successfully applied to systematic studies of the elastic charge electron scattering from even-even exotic nuclei. The extension of this method to investigate the elastic magnetic electron scattering from odd-A exotic nuclei is a natural generalization. The experimental form factors of 17 O and 41 Ca are reproduced very well with the help of the spectroscopic factors which are introduced into the relativistic treatment of the magnetic electron scattering for the first time. The emphases are put on the magnetic form factors of 15,17,19 C, 23 O, 17 F, and 49,59 Ca calculated in the relativistic impulse approximation. Great differences have been found in the form factors of the same nucleus with different configurations. Therefore, the elastic magnetic electron scattering can be used to determine the orbital of the last nucleon of odd-A exotic nuclei. Our results can provide references for the electron scattering from exotic nuclei in the near future

  14. The anatomy of the vestibular nuclei.

    Science.gov (United States)

    Highstein, Stephen M; Holstein, Gay R

    2006-01-01

    The vestibular portion of the eighth cranial nerve informs the brain about the linear and angular movements of the head in space and the position of the head with respect to gravity. The termination sites of these eighth nerve afferents define the territory of the vestibular nuclei in the brainstem. (There is also a subset of afferents that project directly to the cerebellum.) This chapter reviews the anatomical organization of the vestibular nuclei, and the anatomy of the pathways from the nuclei to various target areas in the brain. The cytoarchitectonics of the vestibular brainstem are discussed, since these features have been used to distinguish the individual nuclei. The neurochemical phenotype of vestibular neurons and pathways are also summarized because the chemical anatomy of the system contributes to its signal-processing capabilities. Similarly, the morphologic features of short-axon local circuit neurons and long-axon cells with extrinsic projections are described in detail, since these structural attributes of the neurons are critical to their functional potential. Finally, the composition and hodology of the afferent and efferent pathways of the vestibular nuclei are discussed. In sum, this chapter reviews the morphology, chemoanatomy, connectivity, and synaptology of the vestibular nuclei.

  15. Adipocyte nuclei captured from VAT and SAT.

    Science.gov (United States)

    Ambati, Suresh; Yu, Ping; McKinney, Elizabeth C; Kandasamy, Muthugapatti K; Hartzell, Diane; Baile, Clifton A; Meagher, Richard B

    2016-01-01

    Obesity-related comorbidities are thought to result from the reprogramming of the epigenome in numerous tissues and cell types, and in particular, mature adipocytes within visceral and subcutaneous adipose tissue, VAT and SAT. The cell-type specific chromatin remodeling of mature adipocytes within VAT and SAT is poorly understood, in part, because of the difficulties of isolating and manipulating large fragile mature adipocyte cells from adipose tissues. We constructed MA-INTACT (Mature Adipocyte-Isolation of Nuclei TAgged in specific Cell Types) mice using the adiponectin (ADIPOQ) promoter (ADNp) to tag the surface of mature adipocyte nuclei with a reporter protein. The SUN1mRFP1Flag reporter is comprised of a fragment of the nuclear transmembrane protein SUN1, the fluorescent protein mRFP1, and three copies of the Flag epitope tag. Mature adipocyte nuclei were rapidly and efficiently immuno-captured from VAT and SAT (MVA and MSA nuclei, respectively), of MA-INTACT mice. MVA and MSA nuclei contained 1,000 to 10,000-fold higher levels of adipocyte-specific transcripts, ADIPOQ, PPARg2, EDNRB, and LEP, relative to uncaptured nuclei, while the latter expressed higher levels of leukocyte and endothelial cell markers IKZF1, RETN, SERPINF1, SERPINE1, ILF3, and TNFA. MVA and MSA nuclei differentially expressed several factors linked to adipogenesis or obesity-related health risks including CEBPA, KLF2, RETN, SERPINE1, and TNFA. The various nuclear populations dramatically differentially expressed transcripts encoding chromatin remodeler proteins regulating DNA cytosine methylation and hydroxymethylation (TETs, DNMTs, TDG, GADD45s) and nucleosomal histone modification (ARID1A, KAT2B, KDM4A, PRMT1, PRMT5, PAXIP1). Remarkably, MSA and MVA nuclei expressed 200 to 1000-fold higher levels of thermogenic marker transcripts PRDM16 and UCP1. The MA-INTACT mouse enables a simple way to perform cell-type specific analysis of highly purified mature adipocyte nuclei from VAT and SAT

  16. Pollen grains are efficient cloud condensation nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Pope, F D, E-mail: fdp21@cam.ac.uk [Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW (United Kingdom)

    2010-10-15

    This letter presents a laboratory study investigating the ability of pollen grains to act as cloud condensation nuclei. The hygroscopicity of pollen is measured under subsaturated relative humidities using an electrodynamic balance. It is found, along with other results, that pollen exhibits bulk uptake of water under subsaturated conditions. Through the use of an environmental scanning electron microscope it was observed that the surface of pollen is wettable at high subsaturated humidities. The hygroscopic response of the pollen to subsaturated relative humidities is parametrized using {kappa}-Koehler theory and values of the parameter {kappa} for pollen are between 0.05 and 0.1. It is found that while pollen grains are only moderately hygroscopic, they can activate at critical supersaturations of 0.001% and lower, and thus pollen grains will readily act as cloud condensation nuclei. While the number density of pollen grains is too low for them to represent a significant global source of cloud condensation nuclei, the large sizes of pollen grains suggest that they will be an important source of giant cloud condensation nuclei. Low temperature work using the environmental scanning electron microscope indicated that pollen grains do not act as deposition ice nuclei at temperatures warmer than - 15 deg. C.

  17. 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)

  18. 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

  19. Fast neutron inelastic scattering from nuclei

    International Nuclear Information System (INIS)

    Lachkar, J.

    1978-01-01

    The need for accurate values of inelastic scattering cross sections appears when the requests for neutron data for reactors and other applied purposes are considered. These requests are partly related to values for spherical nuclei, well studied over many years. These studies were extensively considered in two review papers presented, in 1976, at the International Conference on the Interactions of Neutrons with nuclei. Other requests are related to vibrational and rotational nuclei, and relevant studies have been recently performed. The quality of these investigations and the large number of recent results have lead to concentration on them as the topic of the present review. The constant improvements of the experimental techniques permits precise measurements of inelastic scattering cross sections to the first excited levels over a range of incident energies, such that different reactions mechanisms are predominant in different parts of that range of energies. Quadrupole, hexadecapole and octupole deformation parameters of the target nuclei can be deduced from the data using phenomenological models. The successful application of the analysis over the range of energies leads to the conclusion that reliable information on the shape of the nuclei has been derived. The validity of the various models, which include direct interaction and compound nucleus reaction mechanisms, is discussed in connection with analyses of recent experiments. (author) [fr

  20. Training nuclei detection algorithms with simple annotations

    Directory of Open Access Journals (Sweden)

    Henning Kost

    2017-01-01

    Full Text Available Background: Generating good training datasets is essential for machine learning-based nuclei detection methods. However, creating exhaustive nuclei contour annotations, to derive optimal training data from, is often infeasible. Methods: We compared different approaches for training nuclei detection methods solely based on nucleus center markers. Such markers contain less accurate information, especially with regard to nuclear boundaries, but can be produced much easier and in greater quantities. The approaches use different automated sample extraction methods to derive image positions and class labels from nucleus center markers. In addition, the approaches use different automated sample selection methods to improve the detection quality of the classification algorithm and reduce the run time of the training process. We evaluated the approaches based on a previously published generic nuclei detection algorithm and a set of Ki-67-stained breast cancer images. Results: A Voronoi tessellation-based sample extraction method produced the best performing training sets. However, subsampling of the extracted training samples was crucial. Even simple class balancing improved the detection quality considerably. The incorporation of active learning led to a further increase in detection quality. Conclusions: With appropriate sample extraction and selection methods, nuclei detection algorithms trained on the basis of simple center marker annotations can produce comparable quality to algorithms trained on conventionally created training sets.

  1. Critical and shape-unstable nuclei

    CERN Document Server

    Cailliau, M; Husson, J P; Letessier, J; Mang, H J

    1973-01-01

    The authors' experimental work on the decay of neutron deficient mercury osmium nuclei, some other studies at ISOLDE (CERN) and their first theoretical analysis show that the nuclei around /sup 186/Pt (Z=78, N=108) are at the limit of spherical, oblate, prolate nuclei, have (the even one) their first 0/sup +/ excited states at very low energy; quasi- rotational bands are associated to these states. The energy of this O/sup +/ state in /sup 186-/Pt deviate from the Kumar value: angular shape instability is not enough to explain this result. The authors look at radial shape and pairing fluctuations. The position of the 4p-4n state must also be known. (0 refs).

  2. Structure and reactions of light exotic nuclei

    International Nuclear Information System (INIS)

    Suzuki, Y.; Yabana, Y.; Lovas, R.G.; Varga, K.

    1998-01-01

    With the advent of radioactive beams, light exotic nuclei have come to the focus of a great number of investigations. The most prominent phenomena found are the neutron halos. A fundamental and yet feasible microscopic approach has been developed to the description of light exotic nuclei. A comprehensive and didactically balanced review of the structure and reaction theory of light exotic nuclei is being developed. This general structure theory has been written up. This is followed by a brief review of cluster models, and that paves the way before introducing the multicluster approximation. That is the apt point to clarify the relationship of the microscopic multicluster approach to other microscopic approaches and to macroscopic models. The structure theory part is then completed with a review of calculations for actual cases. (K.A.)

  3. Reflections on cavitation nuclei in water

    DEFF Research Database (Denmark)

    Mørch, Knud Aage

    2007-01-01

    to explaining why the tensile strength of water varies so dramatically between the experiments reported. A model for calculation of the critical pressure of skin-covered free gas bubbles as well as that of interfacial gaseous nuclei covered by a skin is presented. This model is able to bridge the apparently......The origin of cavitation bubbles, cavitation nuclei, has been a subject of debate since the early years of cavitation research. This paper presents an analysis of a representative selection of experimental investigations of cavitation inception and the tensile strength of water. At atmospheric...... pressure, the possibility of stabilization of free gas bubbles by a skin has been documented, but only within a range of bubble sizes that makes them responsible for tensile strengths up to about 1.5 bar, and values reaching almost 300 bar have been measured. However, cavitation nuclei can also be harbored...

  4. Superscaling and nucleon momentum distributions in nuclei

    International Nuclear Information System (INIS)

    Antonov, A.

    2005-01-01

    The scaling functions f(ψ ' ) and F(y) from the ψ ' - and y-scaling analyses of inclusive electron scattering from nuclei are constructed within the Coherent Density Fluctuation Model (CDFM) using its two equivalent formulations based on either the local density or the nucleon momentum distribution (NMD). The approach is a natural extension of the relativistic Fermi-gas model to finite realistic nuclear systems. The calculations show that the high-momentum components of NMD in the CDFM and their similarity for different nuclei lead to quantitative description of the super-scaling phenomenon and to a good agreement with the experimental data for y ' ' ' - and y-scaling are informative for NMDs at momenta not larger than 2.0-2.5 fm -1 . The work shows the role of both basic quantities, the momentum and density distributions, for the explanation of super-scaling in inclusive electron scattering from nuclei

  5. Particle-rotation coupling in atomic nuclei

    International Nuclear Information System (INIS)

    Almberger, J.

    1980-01-01

    Recently an increased interest in the rotational nuclei has been spurred by the new experimental high-spin activities and by the possibilities for lower spins to interpret an impressive amount of experimental data by some comparatively simple model calculations. The author discusses the particle modes of excitation for rotational nuclei in the pairing regime where some puzzles in the theoretical description remain to be resolved. A model comparison is made between the particle-rotor and cranking models which have different definitions of the collective rotation. The cranking model is found to imply a smaller value of the quasiparticle spin alignment than the particle-rotor model. Rotational spectra for both even and odd nuclei are investigated with the use of the many-BCS-quasiparticles plus rotor model. This model gives an accurate description of the ground and S-bands in many even-even rare-earth nuclei. However, the discrepancies for odd-A nuclei between theory and experiments point to the importance of additional physical components. Therefore the rotationally induced quadrupole pair field is considered. This field has an effect on the low spin states in odd-A nuclei, but is not sufficient to account for the experimental data. Another topic considered is the interaction matrix element in crossings for given spin between quasiparticle rotational bands. The matrix elements are found to oscillate as a function of the number of particles, thereby influencing the sharpness of the backbending. Finally the low-spin continuation of the S-band is studied and it is shown that such states can be populated selectively by means of one-particle pickup reactions involving high angular momentum transfer. (Auth.)

  6. Medium energy hadron scattering from nuclei

    International Nuclear Information System (INIS)

    Ginocchio, J.N.; Wenes, G.

    1986-01-01

    The Glauber approximation for medium energy scattering of hadronic projectiles from nuclei is combined with the interacting boson model of nuclei to produce a transition matrix for elastic and inelastic scattering in algebraic form which includes coupling to all the intermediate states. We present closed form analytic expresions for the transition matrix elements for the three dynamical symmetries of the interacting boson model; that is for, a spherical quadrupole vibrator, a γ unstable rotor, and both prolate and oblate axially symmetric rotors. We give examples of application of this formalism to proton scattering from 154 Sm and 154 Gd. 27 refs., 5 figs., 1 tab

  7. Virtual photon spectra for finite nuclei

    International Nuclear Information System (INIS)

    Wolynec, E.; Martins, M.N.

    1988-01-01

    The experimental results of an isochromat of the virtual photon spectrum, obtained by measuring the number of ground-state protons emitted by the 16.28 MeV isobaric analogue state in 90 Zr as a function of electron incident energy in the range 17-105 MeV, are compared with the values predicted by a calculation of the E1 DWBA virtual photon spectra for finite nuclei. It is found that the calculations are in excellent agreement with the experimental results. The DWBA virtual photon spectra for finite nuclei for E2 and M1 multipoles are also assessed. (author) [pt

  8. 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

  9. Dissipation and the population of compound nuclei

    International Nuclear Information System (INIS)

    Thoennessen, M.; Beene, J.R.

    1992-01-01

    The importance of nuclear dissipative efforts on the formation of compound nuclei is studied with the γ-ray decay of the giant dipole resonance (GDR) built on highly excited states. The compound nuclei 164 Yb, 160 Er, and 110 Sn were produced with very mass-asymmetric and with more mass-symmetric target/projectile combinations. The large deviation from statistical model prediction observed in the γ-ray spectra from the more symmetrically formed 160 Er and 164 Yb can be qualitatively explained within the particle exchange model

  10. Monte Carlo approaches to light nuclei

    International Nuclear Information System (INIS)

    Carlson, J.

    1990-01-01

    Significant progress has been made recently in the application of Monte Carlo methods to the study of light nuclei. We review new Green's function Monte Carlo results for the alpha particle, Variational Monte Carlo studies of 16 O, and methods for low-energy scattering and transitions. Through these calculations, a coherent picture of the structure and electromagnetic properties of light nuclei has arisen. In particular, we examine the effect of the three-nucleon interaction and the importance of exchange currents in a variety of experimentally measured properties, including form factors and capture cross sections. 29 refs., 7 figs

  11. Monte Carlo approaches to light nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Carlson, J.

    1990-01-01

    Significant progress has been made recently in the application of Monte Carlo methods to the study of light nuclei. We review new Green's function Monte Carlo results for the alpha particle, Variational Monte Carlo studies of {sup 16}O, and methods for low-energy scattering and transitions. Through these calculations, a coherent picture of the structure and electromagnetic properties of light nuclei has arisen. In particular, we examine the effect of the three-nucleon interaction and the importance of exchange currents in a variety of experimentally measured properties, including form factors and capture cross sections. 29 refs., 7 figs.

  12. Selfconsistent theory of Coulomb mixing in nuclei

    International Nuclear Information System (INIS)

    Pyatov, N.I.

    1978-01-01

    The theory of isobaric states is considered according to the Coulomb mixing in nuclei. For a given form of the isovestor potential the separable residual interactions are constructed by means of the isotopic invariance principle. The strength parameter of the force is found from a selfconsistency condition. The charge dependent force is represented by the Coulomb effective potential. The theory of the isobaric states is developed using the random phase approximation. The Coulomb mixing effects in the ground and isobaric 0 + states of even-mass nuclei are investigated

  13. Computer Model Of Fragmentation Of Atomic Nuclei

    Science.gov (United States)

    Wilson, John W.; Townsend, Lawrence W.; Tripathi, Ram K.; Norbury, John W.; KHAN FERDOUS; Badavi, Francis F.

    1995-01-01

    High Charge and Energy Semiempirical Nuclear Fragmentation Model (HZEFRG1) computer program developed to be computationally efficient, user-friendly, physics-based program for generating data bases on fragmentation of atomic nuclei. Data bases generated used in calculations pertaining to such radiation-transport applications as shielding against radiation in outer space, radiation dosimetry in outer space, cancer therapy in laboratories with beams of heavy ions, and simulation studies for designing detectors for experiments in nuclear physics. Provides cross sections for production of individual elements and isotopes in breakups of high-energy heavy ions by combined nuclear and Coulomb fields of interacting nuclei. Written in ANSI FORTRAN 77.

  14. Weak and electromagnetic interactions in nuclei

    International Nuclear Information System (INIS)

    Klapdor, H.V.

    1986-01-01

    The International Symposium W.E.I.N. 1986 brought together leading experts in the fields of nuclear and elementary particle physics, astrophysics and cosmology. In addition to current problems in nuclear physics (weak and electromagnetic nuclear properties, electroweak interactions in nuclei, exotic nuclei) this book presents fascinating contributions that arise from the interaction among these fields: lepton number violation and neutrino mass; muon physics; weak interactions and fundamental symmetries; fundamental decays; basic experiments for GUTs; weak interactions and astrophysics; GUTs, SUSYs and the early Universe. The book demonstrates that in this context nuclear physics promises exciting future developments. (orig.)

  15. DNA Measurement of Overlapping Cell Nuclei in Thick Tissue Sections

    Directory of Open Access Journals (Sweden)

    Liang Ji

    1997-01-01

    Full Text Available The paper describes an improved image analysis procedure for measuring the DNA content of cell nuclei in thick sections of liver tissue by absorption densitometry. Whereas previous methods only permitted the analysis of isolated nuclei, the new technique enables both isolated and overlapping nuclei to be measured. A 3D segmentation procedure determines whether each object is an isolated nucleus or a pair of overlapping nuclei; in the latter case the combined optical density is redistributed to the individual nuclei. A selection procedure ensures that only complete nuclei are measured.

  16. High-spin structure of neutron-rich Dy isotopes

    Indian Academy of Sciences (India)

    Phys. A110, 529 (1968). [5] A Alzner, E Bodenstedt, B Gemünden, J van den Hoff and H Reif, Z. Phys. A322, 467 (1985). [6] C E Doran, H H Bolotin, A E Stuchbery and A P Byrne, Z. Phys. A325, 285 (1986). [7] F Brandolini, M De Poli, P Pavan, R V Ribas, D Bazzacco and C R Rosso-Alvarez, Euro. Phys. J. A6, 149 (1999).

  17. Dynamics of fragment formation in neutron-rich matter

    Science.gov (United States)

    Alcain, P. N.; Dorso, C. O.

    2018-01-01

    Background: Neutron stars are astronomical systems with nucleons subjected to extreme conditions. Due to the longer range Coulomb repulsion between protons, the system has structural inhomogeneities. Several interactions tailored to reproduce nuclear matter plus a screened Coulomb term reproduce these inhomogeneities known as nuclear pasta. These structural inhomogeneities, located in the crusts of neutron stars, can also arise in expanding systems depending on the thermodynamic conditions (temperature, proton fraction, etc.) and the expansion velocity. Purpose: We aim to find the dynamics of the fragment formation for expanding systems simulated according to the little big bang model. This expansion resembles the evolution of merging neutron stars. Method: We study the dynamics of the nucleons with semiclassical molecular dynamics models. Starting with an equilibrium configuration, we expand the system homogeneously until we arrive at an asymptotic configuration (i.e., very low final densities). We study, with four different cluster recognition algorithms, the fragment distribution throughout this expansion and the dynamics of the cluster formation. Results: Studying the topology of the equilibrium states, before the expansion, we reproduced the known pasta phases plus a novel phase we called pregnocchi, consisting of proton aggregates embedded in a neutron sea. We have identified different fragmentation regimes, depending on the initial temperature and fragment velocity. In particular, for the already mentioned pregnocchi, a neutron cloud surrounds the clusters during the early stages of the expansion, resulting in systems that give rise to configurations compatible with the emergence of the r process. Conclusions: We showed that a proper identification of the cluster distribution is highly dependent on the cluster recognition algorithm chosen, and found that the early cluster recognition algorithm (ECRA) was the most stable one. This approach allowed us to identify the dynamics of the fragment formation. These calculations pave the way to a comparison between Earth experiments and neutron star studies.

  18. Collinear resonant ionization spectroscopy for neutron rich copper isotopes

    CERN Multimedia

    This proposal aims to study the spins, magnetic moments and quadrupole moments of copper isotopes A=76-78. The information obtained from this experiment will provide an independent and more precise measurement of the magnetic moment of $^{77}$Cu and values for the spins and magnetic moments of $^{76,78}$Cu as well as the quadrupole moments of $^{76-78}$Cu.

  19. Radioactivity of neutron rich oxygen, fluorine and neon isotopes

    International Nuclear Information System (INIS)

    Reed, A.T.; Page, R.D.; Tarasov, O.

    1999-01-01

    The γ-radiation and neutrons emitted following the β-decays of 24 O, 25-27 F and 28-30 Ne have been measured. The nuclides were produced in the quasi-fragmentation of a 78 MeV/A 36 S beam, separated in-flight and identified through time-of-flight and energy loss measurements. The ions were stopped in a silicon detector system, which was used to detect the β-particles emitted in their subsequent radioactive decay. The coincident γ-rays were measured using four large Ge detectors mounted close to the implantation point and the neutrons were detected using forty-two 3 He proportional counters. The measured γ-ray energy spectra are compared with shell model calculations and, where available, the level energies are deduced from transfer reactions

  20. Excited states in the neutron-rich nucleus F-25

    Czech Academy of Sciences Publication Activity Database

    Vajta, Zs.; Stanoiu, M.; Sohler, D.; Jansen, G. R.; Azaiez, F.; Dombrádi, Zs.; Sorlin, O.; Brown, B. A.; Belleguic, M.; Borcea, C.; Bourgeois, C.; Dlouhý, Zdeněk; Elekes, Z.; Fülöp, Zs.; Grévy, S.; Guillemaud-Mueller, D.; Hagen, G.; Hjorth-Jensen, M.; Ibrahim, F.; Kerek, A.; Krasznahorkay, A.; Lewitowicz, M.; Lukyanov, S.; Mandal, S.; Mayet, P.; Mrázek, Jaromír; Negoita, F.; Penionzhkevich, Y. E.; Podolyák, Zs.; Roussel-Chomaz, P.; Saint-Laurent, M. G.; Savajols, H.; Sletten, G.; Timár, J.; Timis, C.; Yamamoto, A.

    2014-01-01

    Roč. 89, č. 5 (2014), 054323 ISSN 0556-2813 Institutional support: RVO:61389005 Keywords : nucleus F-25 * gamma-ray spectroscopy Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 3.733, year: 2014