| 1. |
- Al-Khatib, A, et al.
(författare)
-
Transition to non-collective states at high spin in Xe-124
- 2008
-
Ingår i: European Physical Journal A. Hadrons and Nuclei. - : Springer Science and Business Media LLC. - 1434-6001. ; 36:1, s. 21-29
-
Tidskriftsartikel (refereegranskat)abstract
- Excited states in Xe-124 were populated in the reaction Se-82(Ca-48, 6n) Xe-124 and gamma-ray coincidence relationships were measured with the Gammasphere spectrometer. Two new bands are observed and several of the previously known bands are extended in the high-as well as in the low-spin region. Two irregular high-spin structures are also added. The irregularities are a fingerprint of a transition from collective to non-collective behaviour. Configuration assignments to the new structures are proposed on the basis of systematics and by comparing experimental properties with calculations within the framework of the cranking model.
|
|
| 2. |
- Andersson, Lise-Lotte, et al.
(författare)
-
Extensive Gamma-ray Spectroscopy of Normally and Superdeformed Structures in 61Cu
- 2008
-
Ingår i: European Physical Journal A. Hadrons and Nuclei. - : Springer Science and Business Media LLC. - 1434-6001. ; 36:3, s. 251-278
-
Tidskriftsartikel (refereegranskat)abstract
- A largely extended experimental knowledge of the Cu-61(29)32 nucleus has been obtained from three experiments. Excited states in Cu-61 were produced via the fusion-evaporation reaction Si-28(Ar-36, 3p)Cu-61. In addition to the Ge array GAMMASPHERE, neutron and charged-particle detectors placed around the target position were used for high-performance particle spectroscopy. The constructed level scheme includes more than 160 energy levels and 320 gamma-ray transitions belonging to both normally deformed as well as superdeformed rotational structures. The multipolarities have been determined for the gamma-ray transitions and as a result spin-parity assignments are given for nearly all energy levels. Experimental results in the normally deformed region are compared with predictions from large-scale shell model calculations. The collective structures are compared with results from cranked Nilsson-Strutinsky calculations. The results reveal the need to modify the standard Nilsson parameters in the mass A similar to 60 region.
|
|
| 3. |
- Andersson, Lise-Lotte, et al.
(författare)
-
Gamma-ray Spectroscopy of Excited States in 61Zn
- 2006
-
Ingår i: European Physical Journal A. Hadrons and Nuclei. - : Springer Science and Business Media LLC. - 1434-6001. ; 30:2, s. 381-390
-
Tidskriftsartikel (refereegranskat)abstract
- The Zn-61(30)31 isotope has been produced at the Oak Ridge National Laboratory in the fusion-evaporation reaction Ca-40(Mg-24, 2pn)Zn-61 at 104 MeV. The experimental set-up allowed gamma-rays to be detected in the CLARION Ge detector array in coincidence with the detection of recoiling nuclei in the focal plane at the end of the recoil mass spectrometer. This provides a unique identification of gamma-rays belonging to Zn-61. The excited states have been explored by means of recoil-gamma gamma coincidences, and the resulting decay scheme comprises almost 70 transitions. The data reveal numerous non-yrast states and suggest a revised spin and parity assignment for a previously observed superdeformed band. The resulting decay scheme is compared to predictions from different sets of large-scale shell model calculations.
|
|
| 4. |
- Assié, M., et al.
(författare)
-
Neutron correlations in 6He viewed through nuclear break-up
- 2009
-
Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 42:3, s. 441-446
-
Tidskriftsartikel (refereegranskat)abstract
- The nuclear break-up of He-6 on a Pb-208 target was studied at 20 A MeV using a secondary beam of He-6 produced by the SPIRAL facility at GANIL. alpha-particles were detected in coincidence with two neutrons with a large angular coverage and the reaction mechanism was identified. From the distribution of the relative angles between the two neutrons the correlation function was extracted. It shows a strong correlation at small relative angles attributed to the contribution of the di-neutron configuration of He-6.
|
|
| 5. |
- Becker, F, et al.
(författare)
-
Status of the RISING Project at GSI
- 2005
-
Ingår i: European Physical Journal A. Hadrons and Nuclei. - : Springer Science and Business Media LLC. - 1434-6001. ; 25:Suppl 1, s. 719-722
-
Tidskriftsartikel (refereegranskat)abstract
- The FRS-RISING set-up at GSI uses secondary radioactive beams at relativistic energies for nuclear structure studies. At GSI the fragmentation or fission of stable primary beams up to U-238 provide secondary beams with sufficient intensity to perform gamma-ray spectroscopy. The RISING set-up is described and results of the first RISING campaign are presented. New experimental methods at relativistic energies are being investigated. Future experiments focus on state-of-the art nuclear structure physics covering exotic nuclei all over the nuclear chart.
|
|
| 6. |
- Bemmerer, D., et al.
(författare)
-
Feasibility of low-energy radiative-capture experiments at the LUNA underground accelerator facility
- 2005
-
Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 24:2, s. 313-319
-
Tidskriftsartikel (refereegranskat)abstract
- The LUNA (Laboratory Underground for Nuclear Astrophysics) facility has been designed to study nuclear reactions of astrophysical interest. It is located deep underground in the Gran Sasso National Laboratory, Italy. Two electrostatic accelerators, with 50 and 400 kV maximum voltage, in combination with solid and gas target setups allowed to measure the total cross-sections of the radiative-capture reactions 2H2H(p, γ) 3He3Heand 14N14N(p, γ) 15O15Owithin their relevant Gamow peaks. We report on the gamma background in the Gran Sasso laboratory measured by germanium and bismuth germanate detectors, with and without an incident proton beam. A method to localize the sources of beam-induced background using the Doppler shift of emitted gamma rays is presented. The feasibility of radiative-capture studies at energies of astrophysical interest is discussed for several experimental scenarios. © Società Italiana di Fisica/Springer-Verlag 2005.
|
|
| 7. |
- Bogner, S. K., et al.
(författare)
-
Density matrix expansion for low-momentum interactions
- 2009
-
Ingår i: European Physical Journal A. - 1434-601X .- 1434-6001. ; 39:2, s. 219-241
-
Tidskriftsartikel (refereegranskat)abstract
- A first step toward a universal nuclear energy density functional based on low-momentum interactions is taken using the density matrix expansion (DME) of Negele and Vautherin. The DME is adapted for non-local momentum space potentials and generalized to include local three-body interactions. Different prescriptions for the three-body DME are compared. Exploratory results are given at the Hartree-Fock level, along with a roadmap for systematic improvements within an effective action framework for the Kohn-Sham density functional theory.
|
|
| 8. |
- Caamano, M, et al.
(författare)
-
Isomers in neutron-rich A approximate to 190 nuclides from Pb-208 fragmentation
- 2005
-
Ingår i: European Physical Journal A. Hadrons and Nuclei. - : Springer Science and Business Media LLC. - 1434-6001. ; 23:2, s. 201-215
-
Tidskriftsartikel (refereegranskat)abstract
- Relativistic projectile fragmentation of Pb-208 has been used to produce isomers in neutron-rich, A approximate to 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 Ta-188, W-190, Re-192, Re-193, Os-195, Ir-197, Ir-198, Pt-200, Pt-201, Pt-202 and Au-203, with half-lives ranging from approximately 10 ns to 1 ms. Tentative isomer information has been found also for Er-174, Er-175, Hf-185, Re-191, Re-194 and Ir-199. In most cases, time-correlated, singles gamma-ray events provided the first spectroscopic data on excited states for each nuclide. In Pt-200 and Pt-201. 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.
|
|
| 9. |
- Cortina-Gil, D., et al.
(författare)
-
One-neutron knockout of O-23
- 2005
-
Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-601X .- 1434-6001. ; 25, s. 343-346
-
Konferensbidrag (refereegranskat)abstract
- Breakup reactions were used to study the ground-state configuration of the neutron-rich isotope O-23. The O-22 fragments produced in one-nucleon removal from O-23 at 938 MeV/nucleon in a carbon target were detected in coincidence with de-exciting gamma rays, allowing to discern between 220 ground-state and excited-states contributions. From the comparison of exclusive experimental momentum distributions for the one-neutron removal channel to theoretical momentum distributions calculated in an Eikonal model for the knockout process, and spin and parity assignment of I-pi = 1/2(+) was deduced for the 230 ground state. This result solved the existent experimental discrepancy.
|
|
| 10. |
- Csanad, M., et al.
(författare)
-
Universal scaling of the elliptic flow data at RHIC
- 2008
-
Ingår i: European Physical Journal A. Hadrons and Nuclei. - : Springer Science and Business Media LLC. - 1434-6001. ; 38:3, s. 363-368
-
Tidskriftsartikel (refereegranskat)abstract
- Recent PHOBOS measurements of the excitation function for the pseudo-rapidity dependence of the elliptic flow in Au + Au collisions at RHIC have posed a significant theoretical challenge. Here we show that these differential measurements, as well as the RHIC measurements on transverse momentum satisfy a universal scaling relation predicted by the Buda-Lund model, based on exact solutions of perfect fluid hydrodynamics. We also show that the recently found transverse kinetic energy scaling of the elliptic flow is a special case of this universal scaling.
|
|
| 11. |
- De Oliveira Santos, F., et al.
(författare)
-
Study of 19Na at SPIRAL
- 2005
-
Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-601X .- 1434-6001. ; 24:2, s. 237-247
-
Tidskriftsartikel (refereegranskat)abstract
- The excitation function for the elastic-scattering reaction p( 18 Ne, p) 18 Ne was measured with the first radioactive beam from the SPIRAL facility at the GANIL laboratory and with a solid cryogenic hydrogen target. Several broad resonances have been observed, corresponding to new excited states in the unbound nucleus 19 Na. In addition, two-proton emission events have been identified and are discussed.
|
|
| 12. |
- Ekman, Jörgen, et al.
(författare)
-
News on Mirror Nuclei in the sd and fp Shells
- 2005
-
Ingår i: European Physical Journal A. Hadrons and Nuclei. - : Springer Science and Business Media LLC. - 1434-6001. ; 25:Suppl 1, s. 363-366
-
Tidskriftsartikel (refereegranskat)abstract
- Novel experimental results on mirror nuclei in the sd and fp shells are presented. Their respective Mirror Energy Difference (MED) diagrams are interpreted by means of large-scale shell-model calculations. A unique way of extracting effective charges from isospin symmetry studies is also discussed.
|
|
| 13. |
- Fäldt, Göran, et al.
(författare)
-
Two-pion production in deuteron-deuteron collisions at low energies
- 2006
-
Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 28:2, s. 245-249
-
Tidskriftsartikel (refereegranskat)abstract
- The cross section for the dd->4Hepipi reaction is estimated near threshold in a two-step model where a pion created in the first step produces a second pion in a subsequent interaction.
|
|
| 14. |
- Hammer, H. W., et al.
(författare)
-
Pion-mass dependence of three-nucleon observables
- 2007
-
Ingår i: European Physical Journal A. - 1434-601X .- 1434-6001. ; 32:3, s. 335-347
-
Tidskriftsartikel (refereegranskat)abstract
- We use an effective field theory (EFT) which contains only short-range interactions to study the dependence of a variety of three-nucleon observables on the pion mass. The pion-mass dependence of input quantities in our "pionless" EFT is obtained from a recent chiral EFT calculation. To the order we work at, these quantities are the S-1(0) scattering length and effective range, the deuteron binding energy, the S-3(1) effective range, and the binding energy of one three-nucleon bound state. The chiral EFT input we use has the inverse S-3(1) and S-1(0) scattering lengths vanishing at m(pi)(crit) stop = 197.8577 MeV. At this "critical" pion mass, the triton has infinitely many excited states with an accumulation point at the three-nucleon threshold. We compute the binding energies of these states up to next-to-next-to-leading order in the pionless EFT and study the convergence pattern of the EFT in the vicinity of the critical pion mass. Furthermore, we use the pionless EFT to predict how doublet and quartet nd scattering lengths depend on m(pi) in the region between the physical pion mass and m(pi) = m(pi)(crit) stop .
|
|
| 15. |
- Ideguchi, E, et al.
(författare)
-
Study of high-spin states in the Ca-48 region by using secondary fusion reactions
- 2005
-
Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 25, s. 429-430
-
Tidskriftsartikel (refereegranskat)abstract
- An in-beam gamma-ray spectroscopy study, following a fusion reaction induced by a neutronrich secondary beam, Ar-46 + Be-9, is presented. A low-energy secondary beam of Ar-46 at similar to 5 MeV/A was developed in order to induce fusion reactions. Gamma-gamma coincidence and excitation function analysis was performed to study high-spin states in the vicinity of Ca-48, Ti49-52.
|
|
| 16. |
- Imbriani, G., et al.
(författare)
-
S-factor of 14N(p,γ)15O at astrophysical energies
- 2005
-
Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 25:3, s. 455-466
-
Tidskriftsartikel (refereegranskat)abstract
- The astrophysical S(E) factor of 14N(p,γ)15O has been measured for effective center-of-mass energies between E eff = 119 and 367 keV at the LUNA facility using TiN solid targets and Ge detectors. The data are in good agreement with previous and recent work at overlapping energies. R-matrix analysis reveals that due to the complex level structure of 15O the extrapolated S(0) value is model dependent and calls for additional experimental efforts to reduce the present uncertainty in S(0) to a level of a few percent as required by astrophysical calculations. © Società Italiana di Fisica / Springer-Verlag 2005.
|
|
| 17. |
- Jeppesen, H. B., et al.
(författare)
-
Alpha-decay half-life of Fr-221 in different environments
- 2007
-
Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-601X .- 1434-6001. ; 32:1, s. 31-34
-
Tidskriftsartikel (refereegranskat)abstract
- A possible dependence of the alpha decay process on the solid-state environment of the decaying nucleus has been investigated by measuring the alpha-decay half-life of Fr-221 at room temperature in different materials (Au, W, Si and polyethylene). The change in half-life between the insulator Si and the metals Au/W is found to be 0.30(17)% / 0.42(21)%, respectivly. Furthermore an improved value of 4.79(2) min was found for the absolute half-life of Fr-221.
|
|
| 18. |
- Johansson, Emma, et al.
(författare)
-
Gamma-ray Spectroscopy of the Doubly Magic Nucleus 56Ni
- 2006
-
Ingår i: European Physical Journal A. Hadrons and Nuclei. - : Springer Science and Business Media LLC. - 1434-6001. ; 27:2, s. 157-165
-
Tidskriftsartikel (refereegranskat)abstract
- The doubly magic N = Z nucleus Ni-56 has been investigated with two fusion-evaporation reactions; Ca-40(Si-28, 3 alpha)Ni-56 at a beam energy of 122MeV and Si-28(S-32, 2p2n)Ni-56 at 130MeV. To detect gamma-rays in coincidence with evaporated particles the Ge-detector array Gammasphere was used in conjunction with the charged-particle detector system, Microball and a 1 pi neutron detector array. Results include a significantly extended level scheme of Ni-56, which is compared to large-scale shell model calculations in the fp shell. The experimental and theoretical results agree to a large extent, with one notable exception; the theoretical model fails to predict the proper sequence of the yrast and yrare 8(+) states.
|
|
| 19. |
- Korgul, A., et al.
(författare)
-
On the unusual properties of the 282 keV state in 135Sb
- 2007
-
Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 32:1, s. 25-29
-
Tidskriftsartikel (refereegranskat)abstract
- Recently the first excited state in 135Sb has been observed at the unexpectedly low excitation energy of only 282keV and interpreted as mainly d 5/2 proton coupled to the 134Sn core. Based on theoretical considerations it was suggested that its low excitation energy is related to a relative shift of the proton d 5/2 and g 7/2 orbits induced by the neutron excess. We have measured the lifetime of the 282keV state by the advanced time-delayed βγγ(t) method. The measured half-life, T 1/2 = 6.1(4)ns, yields exceptionally low limits of B(M1;5/21 +→7/21 +)≤3.0×10-4 μ 2 N and B(E2;5/21 +→7/21 +)≤54e 2 fm 4. These strongly hindered M1 and slow E2 transition rates are similar to those for the transition de-populating the first excited state at 405keV in 211Bi. Results of shell model calculations with realistic interactions are presented. The M1 decay rate was found to be extremely sensistive both to the wave function and to the M1 effective operator.
|
|
| 20. |
- Lieder, E O, et al.
(författare)
-
Investigation of lifetimes in quadrupole bands of Gd-142
- 2008
-
Ingår i: European Physical Journal A. Hadrons and Nuclei. - : Springer Science and Business Media LLC. - 1434-6001. ; 35:2, s. 135-158
-
Tidskriftsartikel (refereegranskat)abstract
- For a level scheme investigation of Gd-142 an experiment with the gamma -spectrometer EUROBALLIII has been carried out and lifetimes have been measured with EUROBALL IV using the Doppler-shift attenuation method. The high-spin states have been populated in these experiments by means of the(99)Ru(Ti-48, 2p3n) reaction at a beam energy of 240MeV and the Sn-114(S-32, 2p2n) reaction at 160MeV, respectively. Reduced E2 transition probabilities B(E2) were determined for 15 members of four quadrupole bands. For the interpretation of the positive-parity even-spin quadrupole bands, calculations in the cranked Nilsson-Strutinsky as well as interacting boson models have been performed. From the former calculations it was concluded that the high-spin states of the (+ , 0)(1) band in Gd-142 represent a triaxial nucleus rotating around the longest principal axis.
|
|
| 21. |
- Mabala, G. K., et al.
(författare)
-
Shears band with a large dynamic moment of inertia in Bi-197
- 2005
-
Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 25:1, s. 49-55
-
Tidskriftsartikel (refereegranskat)abstract
- High-spin states in Bi-197 were studied with the AFRODITE gamma-ray array at iThemba LABS using the Ta-181(Ne-22, 6n) reaction at a beam energy of 125 MeV. A new shears band was found and linked to the low-lying states in Bi-197. Its dynamic moment of inertia, F (2), is considerably larger than the ((2)) of the shears bands in the neighbouring Pb isotopes. This is probably a result of the involvement of an additional high-K h(9/2) proton orbital.
|
|
| 22. |
- Mach, H., et al.
(författare)
-
New structure information on Mg-30, Mg-31 and Mg-32
- 2005
-
Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-601X .- 1434-6001. ; 25, s. 105-109
-
Konferensbidrag (refereegranskat)abstract
- The fast timing beta gamma gamma(t) method was applied to investigate the level lifetimes in Mg-30,Mg-31,Mg-32. Levels in Mg have been populated in beta and beta-delayed neutron emission of Na, at the ISOLDE facility. From the gamma gamma coincidences a number of new states have been identified and new level schemes were constructed for 30 31,32 Mg. The following preliminary half lives have been determined: T-1/2 = 3.9(4) ns for the 1789 keV state in Mg-30, T-1/2 = 133(8) ps and 10.5(8) us for the 221 keV and 461 keV states in Mg-31, respectively, and T1/2 = 16(4) ps for the 885 keV level in 32Mg. The 1789 keV level was established as a candidate for the intruder 0(+) configuration in Mg-30 with a possible strong E0 branch to the ground state.
|
|
| 23. |
- Madurga, M., et al.
(författare)
-
Kinematic identification of the t branch in the decay of 11Li
- 2009
-
Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-601X .- 1434-6001. ; 42:3, s. 415-419
-
Tidskriftsartikel (refereegranskat)abstract
- The -delayed 8 Li + t branch of the 11Li decay was identified via kinematical analysis of the charged particles observed in coincidence. The back-to-back events observed in a narrow angular acceptance were compared to a Monte Carlo simulation. The 8 Li + t sum energy spectrum was fitted assuming that the decay occurs through an intermediate state in 11Be . The resulting energy centroid and full-width half maximum for the intermediate state are 18.35(30)MeV and 1.5(4)MeV, respectively. The -delayed 8 Li + t branching ratio obtained from the coincidence spectrum, BR t = 0.93(8)×10-4 , is in agreement with previous measurements but more precise.
|
|
| 24. |
- Podolyak, Zs., et al.
(författare)
-
Structure of Neutron-rich Nuclei Around the N=126 Closed Shell; the Yrast Structure of 205Au up to Spin-parity I = (19/2+)
- 2009
-
Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 42:3, s. 489-493
-
Konferensbidrag (refereegranskat)abstract
- Heavy neutron-rich nuclei have been populated through the relativistic fragmentation of a Pb-208(82) beam at E/A = 1 GeV on a 2.5 g/cm(2) thick Be target. The synthesised nuclei were selected and identified in-flight using the fragment separator at GSI. Approximately 300 ns after production, the selected nuclei were implanted in an similar to 8 mm thick perspex stopper, positioned at the centre of the RISING gamma-ray detector spectrometer array. A previously unreported isomer with a half-life T-1/2 = 163(5) ns has been observed in the N = 126 closed-shell nucleus Au-205(79). Through gamma-ray singles and gamma-gamma coincidence analysis a level scheme was established. The comparison with a shell model calculation tentatively identifies the spin-parity of the excited states, including the isomer itself, which is found to be I-pi = (19/2(+)).
|
|
| 25. |
- Rudolph, Dirk, et al.
(författare)
-
Evidence for an Isomeric 3/2- State in 53Co
- 2008
-
Ingår i: European Physical Journal A. Hadrons and Nuclei. - : Springer Science and Business Media LLC. - 1434-6001. ; 36:2, s. 131-138
-
Tidskriftsartikel (refereegranskat)abstract
- The fragmentation of a 550MeV/u primary beam of Ni-58 on a Be-9 target has been used to measure time-and energy-correlated gamma decays following the implantation of event-by-event discriminated secondary fragments into a Be-9 stopper plate. A new isomeric gamma decay with T-1/2 = 14(6 4) ns and E-gamma = 646.2(2) keV is observed and attributed to the decay of the yrast 3/2-state in Co-53(27)26. This short-lived isomeric state has been populated by means of nuclear reactions during the stopping process of the secondary fragments. The experimental findings are discussed in the framework of large-scale spherical shell model calculations in conjunction with isospin symmetry-breaking residual interactions for the A = 53, Tz = +/- 1/2 mirror nuclei Co-53 and Fe-53.
|
|
