| 1. |
- Schael, S, et al.
(författare)
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Precision electroweak measurements on the Z resonance
- 2006
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Ingår i: Physics Reports. - : Elsevier BV. - 0370-1573 .- 1873-6270. ; 427:5-6, s. 257-454
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Forskningsöversikt (refereegranskat)abstract
- We report on the final electroweak measurements performed with data taken at the Z resonance by the experiments operating at the electron-positron colliders SLC and LEP. The data consist of 17 million Z decays accumulated by the ALEPH, DELPHI, L3 and OPAL experiments at LEP, and 600 thousand Z decays by the SLID experiment using a polarised beam at SLC. The measurements include cross-sections, forward-backward asymmetries and polarised asymmetries. The mass and width of the Z boson, m(Z) and Gamma(Z), and its couplings to fermions, for example the p parameter and the effective electroweak mixing angle for leptons, are precisely measured: m(Z) = 91.1875 +/- 0.0021 GeV, Gamma(Z) = 2.4952 +/- 0.0023 GeV, rho(l) = 1.0050 +/- 0.0010, sin(2)theta(eff)(lept) = 0.23153 +/- 0.00016. The number of light neutrino species is determined to be 2.9840 +/- 0.0082, in agreement with the three observed generations of fundamental fermions. The results are compared to the predictions of the Standard Model (SM). At the Z-pole, electroweak radiative corrections beyond the running of the QED and QCD coupling constants are observed with a significance of five standard deviations, and in agreement with the Standard Model. Of the many Z-pole measurements, the forward-backward asymmetry in b-quark production shows the largest difference with respect to its SM expectation, at the level of 2.8 standard deviations. Through radiative corrections evaluated in the framework of the Standard Model, the Z-pole data are also used to predict the mass of the top quark, m(t) = 173(+10)(+13) GeV, and the mass of the W boson, m(W) = 80.363 +/- 0.032 GeV. These indirect constraints are compared to the direct measurements, providing a stringent test of the SM. Using in addition the direct measurements of m(t) and m(W), the mass of the as yet unobserved SM Higgs boson is predicted with a relative uncertainty of about 50% and found to be less than 285 GeV at 95% confidence level. (c) 2006 Elsevier B.V. All rights reserved.
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| 2. |
- Atac, A, et al.
(författare)
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Single-step link of the superdeformed band in Eu-143
- 1996
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Ingår i: ZEITSCHRIFT FUR PHYSIK A-HADRONS AND NUCLEI. - : SPRINGER VERLAG. - 0939-7922. ; 355:4, s. 343-344
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- A discrete gamma-ray transition with an energy of 3360.6 keV deexciting the second lowest SD state in Eu-143 has been discovered. It carries 3.2 % of the full intensity of the band and feeds into a nearly spherical state which is above the I = 35/2((+)),
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| 3. |
- Axelsson, A, et al.
(författare)
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Single-step link from yrast SD band in Eu-143
- 1997
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Ingår i: PROGRESS IN PARTICLE AND NUCLEAR PHYSICS. - : PERGAMON PRESS LTD. - 0146-6410. ; 38, s. 51-52
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- A discrete gamma-ray transition from the yrast SD band to the region of near-yrast discrete normal-deformed states has been identified in Eu-143. It has an energy of 3360.6 keV and an intensity corresponding to 3.2% of the full intensity of the SD band an
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| 4. |
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| 5. |
- Gorgen, A, et al.
(författare)
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Quadrupole moments of wobbling excitations in Lu-163
- 2004
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 69:3
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Tidskriftsartikel (refereegranskat)abstract
- Lifetimes of states in the triaxial strongly deformed bands of Lu-163 have been measured with the Gammasphere spectrometer using the Doppler-shift attenuation method. The bands have been interpreted as wobbling-phonon excitations from the characteristic electromagnetic properties of the transitions connecting the bands. Quadrupole moments are extracted for the zero-phonon yrast band and, for the first time, for the one-phonon wobbling band. The very similar results found for the two bands suggest a similar intrinsic structure and support the wobbling interpretation. While the in-band quadrupole moments for the bands show a decreasing trend towards higher spin, the ratio of the interband to the in-band transition strengths remains constant. Both features can be understood by a small increase in triaxiality towards higher spin. Such a change in triaxiality is also found in cranking calculations, to which the experimental results are compared.
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| 6. |
- Jensen, DR, et al.
(författare)
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Coexisting wobbling and quasiparticle excitations in the triaxial potential well of Lu-163
- 2004
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Ingår i: European Physical Journal A. Hadrons and Nuclei. - : Springer Science and Business Media LLC. - 1434-6001. ; 19:2, s. 173-185
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Tidskriftsartikel (refereegranskat)abstract
- High-spin states of the nucleus Lu-163 have been populated through the fusion-evaporation reaction La-139(Si-29, 5n) with a beam energy of 157 MeV. In addition to the two lowest excited triaxial strongly deformed (TSD) bands, recently interpreted as one- and two-phonon wobbling excitations, a third excited TSD band has been firmly established decaying to the yrast TSD band. The assignment of this band as a three-quasiparticle band shows together with the normal deformed (ND) level scheme the presence not only of shape coexistence between ND and TSD structures, but also an interplay of wobbling and quasiparticle excitations in the triaxial strongly deformed potential well of Lu-163.
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| 7. |
- Jensen, DR, et al.
(författare)
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Evidence for second-phonon nuclear wobbling
- 2002
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Ingår i: Physical Review Letters. - 1079-7114. ; 89:14
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Tidskriftsartikel (refereegranskat)abstract
- The nucleus Lu-163 has been populated through the reaction La-139(Si-29,5n) with a beam energy of 157 MeV. Three triaxial, strongly deformed (TSD) bands have been observed with very similar rotational properties. The first excited TSD band has earlier been assigned as a one-phonon wobbling excitation built on the lowest-lying (yrast) TSD band. The large B(E2)(out)/B(E2)(in) value obtainable for one of four observed transitions between the second and first excited TSD bands is in good agreement with particle-rotor calculations for a two-phonon wobbling excitation.
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| 8. |
- Jensen, DR, et al.
(författare)
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Wobbling phonon excitations, coexisting with normal deformed structures in Lu-163
- 2002
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Ingår i: Nuclear Physics, Section A. - 0375-9474. ; 703:1-2, s. 3-44
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Tidskriftsartikel (refereegranskat)abstract
- Wobbling is a rotational mode unique to a triaxial body. The Lu-Hf isotopes with N similar to 94 at high spin provide a possible region of nuclei with pronounced triaxiality. We have investigated Lu-163 through the fusion-evaporation reaction La-139(Si-29,5n)Lu-163 with a beam energy of 152 MeV. Three excited bands decaying into the known, presumably triaxial, superdeformed (TSD) band built on the i(13/2) proton orbital are observed. The electromagnetic properties of the connecting transitions from the two strongest populated excited TSD bands have been investigated. New particle-rotor calculations in which one i(13/2) quasiproton is coupled to the core of triaxial shape produce a variety of bands, whose properties can clearly be interpreted either as "wobbling" or "cranking" motion of the core. Evidence for the assignment of the excited TSD bands as one, and possibly even two wobbling phonon modes built on the yrast TSD band in Lu-163 is given. These triaxial bands coexist with bands built on quasiparticle excitations in the normal deformed (ND) minimum for which new data are also presented.
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| 9. |
- KOMATSUBARA, T, et al.
(författare)
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HIGH-SPIN STATES IN ODD-ODD NUCLEI
- 1993
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Konferensbidrag (refereegranskat)abstract
- High-spin states in doubly odd nuclei of 124Cs, 126Cs and 124La have been investigated by gamma ray spectroscopy. Rotational bands of pih11/2 x nuh11/2 configuration have been assigned by the blocking argument on the first band crossing frequencies for neighboring odd-A nuclei. In cesium isotopes, the signature inversion of quasiparticle routhians has been observed. The spin of the band head in 124Cs has been determined to be (7+) by means of spectroscopic method. This spin assignment implies that the signature inversion occurs at low spin. The signature dependence becomes normal at higher spins than 17hBAR. The occurrence of the signature inversion in the A approximately 130 mass region is discussed by comparing excitation energies, transition intensities and the shell-model orbits of valence nucleons with those of rare-earth nuclei.
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| 10. |
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| 11. |
- Leoni, S, et al.
(författare)
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Four independent decay properties in the super-deformed well of Eu-143
- 1997
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Ingår i: PHYSICS LETTERS B. - : ELSEVIER SCIENCE BV. - 0370-2693. ; 409:1-4, s. 71-76
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The flow of gamma-transitions through the superdeformed minimum of Eu-143 is investigated by studying the intensities of four different types of gamma-rays of superdeformed origin, obtained with a variety of gating conditions. They can all be explained ra
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| 12. |
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| 13. |
- Neusser, A, et al.
(författare)
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Superdeformed band at very high spin in Nd-140
- 2004
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 70:6
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Tidskriftsartikel (refereegranskat)abstract
- A new high-spin superdeformed band has been discovered in Nd-140(60)80. It was populated in the Zr-96(Ca-48,4n) reaction and investigated using the EUROBALL gamma-ray spectrometer array. The band is observed in the approximate spin range of I=36 to 66. It is associated with shell gaps around Z=60 and at N=80 at large deformation. These gaps produce a pronounced minimum in the calculated total Routhian surfaces at a quadrupole deformation of epsilon(2)=0.45. The new band which lies between the high-deformation bands in the Aapproximate to130 region and the superdeformed bands in Aapproximate to150 nuclei provides insight into the development of the deformation between these two regions. Two possible configurations are suggested involving four neutrons of i(13/2) origin (nu6(4)) and either six protons of h(11/2)/h(9/2) origin (pi5(6)) or five protons of h(11/2)/h(9/2) and one of i(13/2) origin (pi5(5)6(1)).
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| 14. |
- Petrache, CM, et al.
(författare)
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Risk of misinterpretation of nearly degenerate pair bands as chiral partners in nuclei
- 2006
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Ingår i: Physical Review Letters. - 1079-7114. ; 96:11
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Tidskriftsartikel (refereegranskat)abstract
- The experimental information on the observed nearly degenerate bands in the N = 75 isotones, in particular Pr-134 and Pm-136, which are often considered as the best candidates for chiral bands, is critically analyzed. Most properties of the bands, in particular, the recently measured branching ratios and lifetimes, are in clear disagreement with the interpretation of the two bands as chiral bands. For I = 14-18 in Pr-134, where the observed energies are almost degenerate, we have obtained a value of 2.0(4) for the ratio of the transition quadrupole moments of the two bands, which implies a considerable difference in the nuclear shape associated with the two bands. The insufficiency of the near-degeneracy criterion to trace nuclear chirality is emphasized.
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| 15. |
- Piiparinen, M, et al.
(författare)
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High-spin spectroscopy of the Eu-142, Eu-143 and Eu-144 nuclei
- 1996
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Ingår i: NUCLEAR PHYSICS A. - : ELSEVIER SCIENCE BV. - 0375-9474. ; 605:2, s. 191-268
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- High-spin level schemes of the Eu-142, Eu-143 and Eu-144 nuclei have been investigated by in-beam gamma-ray spectroscopic methods using the NORDBALL Compton-suppressed multi-detector array. The previously known schemes have been extended to considerably h
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| 16. |
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| 17. |
- Schonwasser, G, et al.
(författare)
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Coexisting normal and triaxial superdeformed structures in Lu-165
- 2004
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Ingår i: Nuclear Physics, Section A. - : Elsevier BV. - 0375-9474. ; 735:3-4, s. 393-424
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Tidskriftsartikel (refereegranskat)abstract
- High-spin states in Lu-165 were populated in the La-139(Si-30, 4n) reaction at a beam energy of 152 MeV and gamma-ray coincidences were measured with the EUROBALL spectrometer array. Nine new rotational bands were discovered, known band structures were considerably extended and many inter-band transitions were found. Structures with normal deformation coexist with bands associated with the strongly deformed triaxial energy minima found in calculations. Three of these triaxial bands form a family of wobbling excitations with phonon quanta n(w) = 0, 1 and 2. The wobbling mode is a unique signature of nuclear triaxiality. Configuration assignments are discussed for the observed band structures. An exchange of configuration between two of the new bands due to mixing is observed, resulting in different signature partnerships at low and high spins.
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| 18. |
- Schonwasser, G, et al.
(författare)
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Lifetimes of triaxial superdeformed states in Lu-163 and Lu-164
- 2002
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Ingår i: European Physical Journal A. Hadrons and Nuclei. - : Springer Science and Business Media LLC. - 1434-6001. ; 13:3, s. 291-296
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Tidskriftsartikel (refereegranskat)abstract
- Lifetimes of states in the yrast superdeformed bands of Lu-163 and Lu-164 were determined in a Doppler-shift attenuation-method experiment. From fractional Doppler shifts and line shapes, average transition quadrupole moments, Q(t) = 8.2(-0.6)(+1.0) b and 7.1(-0.6)(+0.5) 1), were deduced for one of the bands in Lu-163 OX -0.6 and Lu-164, respectively. These values are much larger than the quadrupole moment of the normal-deformed yrast band in Yb-163, Q(t) = 4.9(-0.4)(+1.34) b, that was also determined in this experiment. Comparison to cranking calculations indicates that both superdeformed bands correspond to a local potential energy minimum with a pronounced triaxiality, gamma similar to 20degrees.
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| 19. |
- Schonwasser, G, et al.
(författare)
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One- and two-phonon wobbling excitations in triaxial Lu-165
- 2003
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Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - 0370-2693. ; 552:1-2, s. 9-16
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Tidskriftsartikel (refereegranskat)abstract
- High-spin states in Lu-165 have been investigated by in-beam gamma-ray coincidence spectroscopy using the EUROBALL spectrometer array. Two new excited rotational bands have been discovered with features similar to a previously known triaxial superdeformed band in that nucleus. Comparison of the decay pattern of these bands, in particular the unusually large E2 transition strength from the first excited to the yrast superdeformed band, to theoretical calculations shows that they belong to a family of wobbling excitations with phonon numbers n(w) = 0, 1 and 2. These results, together with evidence for nuclear wobbling in the neighbouring isotopes Lu-163 and Lu-167, firmly establish this mode of excitation in the A = 165 mass region. The observation of wobbling is a unique signature of stable nuclear triaxiality. (C) 2002 Elsevier Science B.V. All rights reserved.
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| 20. |
- Singh, AK, et al.
(författare)
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Evidence for noncollective oblate structures at high spin in Cs-123
- 2004
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 70:3
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Tidskriftsartikel (refereegranskat)abstract
- High-spin states in Cs-123 were populated in the Ni-64(Ni-64,p4n) reaction at a beam energy of 265 MeV. Gamma-ray coincidences were measured using the Gammasphere spectrometer. Two additional bands have been placed in the level scheme and the four previously known bands have been extended to higher spin. At the highest spins, two of the bands show irregular level sequences. These structures of noncollective excitations, which compete with collective rotation, are interpreted as band-terminating states. The results are compared to cranked Nilsson-Strutinsky calculations, and configuration assignments to the bands and to the terminating states are discussed.
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