Author
I. Bergström
Bio: I. Bergström is an academic researcher from CERN. The author has contributed to research in topics: Neutron & Excited state. The author has an hindex of 17, co-authored 34 publications receiving 765 citations.
Topics: Neutron, Excited state, Nucleon, Annihilation, Proton
Papers
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TL;DR: In this paper, the authors surveyed the available experimental material on effective E2 charges in the lead region and found no evidence for a variation in the effective charge of the h 9 2. proton orbital as a function of the number of nucleons outside the core.
67 citations
TL;DR: In this paper, the gamma radiation from excited levels in the even Xe isotopes A = 124, 126, 128, 130 and 132 has been studied using in-beam technique.
56 citations
TL;DR: In this paper, the absorption of stoppedπ− in181Ta and209Bi has been investigated by studying prompt and delayedγ-ray spectra, and absolute cross-sections for the yield of isotopes per capturedπ−, xn) reactions, as well as the relative probability of populating nuclear states of different spins have been measured for the hafnium and lead isotopes, respectively.
Abstract: The absorption of stoppedπ− in181Ta and209Bi has been investigated by studying prompt and delayedγ-ray spectra. Absolute cross-sections for the yield of isotopes per capturedπ− in (π−, xn) reactions, as well as the relative probability of populating nuclear states of different spins have been measured for the hafnium and lead isotopes, respectively. A spin as high as 20 has been observed in the production of204Pb. The ground-state rotational bands of the hafnium isotopes are excited to spin values up to 16. Neutron multiplicities as large as 15 have been observed for both targets. A neutron multiplicity of ≃8 is most probable for both tantalum and bismuth targets.
54 citations
TL;DR: In this article, the high-energy part of the spectrum was used to deduce branching ratios for the so far unobserved annihilation channels: R(p p →π 0 ω) = (2.38 ± 0.65)%, R( p p → π 0 η ) = (0.82 ± 0.04)% and an upper limit for the π0η′ channel was deduced.
48 citations
TL;DR: Using the 204Hg(α,2n) reaction and the pulsed beam of the 225 cm cyclotron, the 12+ and 10+ states of the (i13/2)-2 configuration in 206Pb at the energies 4 027.2 and 3 957.6 keV, respectively, were determined in this paper.
Abstract: Using the 204Hg(α,2n) reaction and the pulsed beam of our 225 cm cyclotron, we have been able to localize the 12+ and 10+ states of the (i13/2)-2 configuration in 206Pb at the energies 4 027.2 and 3 957.6 keV, respectively. It has been possible to determine the partial E2 transition probability for the 12+ → 10+ transition and to derive an effective charge for the i13/2 neutron, which is 0.94±0.04. It is concluded that the quadrupole polarization charge for the i13/2 neutron is about 50% larger than for the h9/2 proton.
43 citations
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TL;DR: In this article, a review of the potential-model approach is presented, together with a brief survey of the motivations for various potential models and the application of the developed theoretical framework.
494 citations
TL;DR: In this paper, a set of nuclear quadrupole moments, Q, for the year-2001 was presented, and a major revision of the value or a considerable improvement of the accuracy was reported for 6 3Li, 7N, 19 9F (197 keV, I = 5/2), 11Na, 13Al, 21Sc, 22Ti, 26Fe (14 keV), I = 3/2 Mossbauer state), 31Ga, 32Ge, 77 34Se (250 keV) and 83Bi.
Abstract: A ‘year-2001’ set of nuclear quadrupole moments, Q, is presented. Compared to the previous, ‘year-1992’ set, a major revision of the value or a considerable improvement of the accuracy is reported for 6 3Li, 7N, 19 9F (197 keV, I = 5/2), 11Na, 13Al, 21Sc, 22Ti, 26Fe (14 keV, I = 3/2 Mossbauer state), 31Ga, 32Ge, 77 34Se (250 keV, I = 5/2 state), 35Br, 36Kr, 37Rb, 39Y, 40Zr, 100 45Rh, 50Sn (24 keV, I = Mossbauer state), 53I, 54Xe, 55Cs and 83Bi.
493 citations
TL;DR: In this article, it was shown that the universe can be a patchwork consisting of distinct regions of matter and antimatter, and that after recombination, it is impossible to avoid annihilation near regional boundaries.
Abstract: We ask whether the universe can be a patchwork consisting of distinct regions of matter and antimatter. We demonstrate that, after recombination, it is impossible to avoid annihilation near regional boundaries. We study the dynamics of this process to estimate two of its signatures: a contribution to the cosmic diffuse γ-ray background and a distortion of the cosmic microwave background. The former signal exceeds observational limits unless the matter domain we inhabit is virtually the entire visible universe. On general grounds, we conclude that a matter-antimatter symmetric universe is empirically excluded.
261 citations
TL;DR: In this paper, a description of high-spin phenomena in atomic nuclei is presented from both the experimental and theoretical points of view, and the characteristic features of collective nuclear motion, such as rotational bands, band crossings, and backbending, as well as noncollective aspects, like high spin isomers and irregular decay patterns are discussed in detail.
Abstract: A description of high-spin phenomena in atomic nuclei is presented from both the experimental and theoretical points of view. The characteristic features of collective nuclear motion, such as rotational bands, band crossings, and backbending, as well as noncollective aspects, like high-spin isomers and irregular decay patterns, are discussed in detail. Recent achievements of the cranking model including the independent quasiparticle and the shell correction methods are reviewed. Changes in the structure of nuclei excited up to the highest possible angular momenta are analyzed; in particular, angular momentum alignment effects, shape changes, possible phase transitions, and sudden rearrangements in the single-particle structure are discussed. Phenomena related to the nuclear quasicontinuum spectra are also examined.
197 citations
TL;DR: In this article, a review on the theory of finite fermi systems and its application to nuclei in the Pb-region is given, where the basic equations are derived and renormalized using the Landau prescription.
192 citations