Halos and related structures

Riisager, K.

doi:10.1088/0031-8949/2013/t152/014001

Cited by 122 publications

(219 citation statements)

References 169 publications

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“…[5][6][7] Such systems do not see details of short-range interactions and their properties can be predicted with any potential that has the same integral properties. Scale invariance noticed in nuclei 5 proved to be applicable also to small atomic clusters.…”

Section: Introductionmentioning

confidence: 99%

Quantum Halo States in Helium Tetramers

2016

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Universality of quantum halo states enables comparison of systems from different fields of physics, as demonstrated in two-and three-body clusters. In the present work, we studied weakly-bound helium tetramers in order to test whether some of these four-body realistic systems qualify as halos. Their ground-state binding energies and structural properties were thoroughly estimated using the diffusion Monte Carlo method with pure estimators. Helium tetramer properties proved to be less sensitive on the potential model than previously evaluated trimer properties. We predict the existence of the realistic four-body halo 4 He 2 3 He 2 , while 4 He 4 and 4 He 3 3 He are close to the border and thus can be used as prototypes of quasi-halo systems. Our results could be tested by experimental determination of tetramers' structural properties, using a similar setup to the one developed for the study of helium trimers.

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Section: Introductionmentioning

confidence: 99%

Quantum Halo States in Helium Tetramers

2016

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“…This discovery has changed the perception of nuclear systems and questioned established knowledge. Although the first anomaly in the expected order of nuclear orbits was observed in 1960 in 11 Be, 18 it was the measurement of the masses of the exotic sodium isotopes, 31,32 Na performed at CERN PS that revealed that these nuclei were tighter bound than expected.…”

Section: Shell Structure: the Decline Of The Magic Numbersmentioning

confidence: 98%

“…8. Many studies have been dedicated to map and define the so-called island of inversion region where 32 Mg is situated in the centre. The 30 Mg (N = 18) isotope has a spherical 0 + ground state with an excited 0 + state at 1788.2 keV.…”

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confidence: 99%

Highlights at ISOLDE

Blaum

Borge

Jonson

et al. 2015

Advanced Series on Directions in High Energy Physics

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The ISOLDE Radioactive Ion Beam Facility at CERN started fifty years ago as an interesting attempt to widen the palette of nuclear species for experimental investigations. During this half century, one has witnessed a continuous development and refinement of the experimental programme. On the road towards today's installation many scientific breakthroughs have been achieved. We present some of them here.

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“…Some indication for decays going directly into the continuum exist for halo nuclei, see [3][4][5] and references therein for details on the halo structure. The two-neutron halo nuclei 6 He and 11 Li appear both to have beta-delayed deuteron emission taking place directly into the continuum [1,6].…”

Section: Beta-particle Decay Mechanismmentioning

confidence: 99%

“…However, this name suggests a two-step process: the beta decay feeding resonance states in the daughter nucleus that subsequently decay by particle emission. The other possible decay mechanism, beta decays feeding the continuum states directly, deserves consideration as well.Some indication for decays going directly into the continuum exist for halo nuclei, see [3][4][5] and references therein for details on the halo structure. The two-neutron halo nuclei 6 He and 11 Li appear both to have beta-delayed deuteron emission taking place directly into the continuum [1,6].…”

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confidence: 99%

Beta decay to continuum states: the case of¹¹Be

Riisager

2014

EPJ Web of Conferences

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Abstract. Beta decay in exotic nuclei can lead to multi-particle final states. This contribution discusses briefly what decay mechanisms may enter in such decays and presents, on behalf of the IS541 collaboration at ISOLDE/CERN, preliminary data from a search for the beta-delayed proton decay of the halo nucleus 11 Be. Beta-particle decay mechanismThe Q-values for beta-decays increase as one moves towards the driplines and eventually become larger than the particle separation energies in the daughter nuclei. This allows population of final states containing, apart from the beta particle and the associated (anti)neutrino, one or more particles (protons, neutrons or heavier particles) in continuum states and a recoiling final nucleus. Such processes allow many different physics questions to be probed experimentally -see [1,2] for recent reviews -and are normally referred to as beta-delayed particle emission. However, this name suggests a two-step process: the beta decay feeding resonance states in the daughter nucleus that subsequently decay by particle emission. The other possible decay mechanism, beta decays feeding the continuum states directly, deserves consideration as well.Some indication for decays going directly into the continuum exist for halo nuclei, see [3][4][5] and references therein for details on the halo structure. The two-neutron halo nuclei 6 He and 11 Li appear both to have beta-delayed deuteron emission taking place directly into the continuum [1,6]. For 11 Li this process has a branching ratio of the order of 10 −4 , the low value mainly being due to the small energy window, whereas cancellation effects reduces the branching ratio for 6 He down to the 10 −6 level. The simple-minded model of the decays is that one of the two halo neutrons beta-decay into a proton and combines with the other one to form a deuteron. A complicating factor in the theoretical description of these two decays is therefore the "two neutron to deuteron" overlap that is sensitive to the correlations between the two neutrons. This is an interesting physics problem, but if the focus is on investigating the decay mechanism a much cleaner case would be the beta-delayed proton decay of a single-neutron halo nucleus. The 11 Be(βp) decayThe most favourable case is 11 Be(βp). Estimates of the branching ratio indicates that this will be a very rare process [7] due to the low energy available, see table 1; the branching ratio will in most a

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Halos and related structures

Cited by 122 publications

References 169 publications

Quantum Halo States in Helium Tetramers

Quantum Halo States in Helium Tetramers

Highlights at ISOLDE

Beta decay to continuum states: the case of¹¹Be

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Halos and related structures

Cited by 122 publications

References 169 publications

Quantum Halo States in Helium Tetramers

Quantum Halo States in Helium Tetramers

Highlights at ISOLDE

Beta decay to continuum states: the case of11Be

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Beta decay to continuum states: the case of¹¹Be