| 11. |
- Madurga, M., et al.
(författare)
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Study of β-delayed charged particle emission of 11Li: Evidence of new decay channels
- 2008
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Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 111:1
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Tidskriftsartikel (refereegranskat)abstract
- The break-up of the 18.2 MeV state in 11Be was studied in a 11Li β-decay experiment. We report here on the study of the dominating breakup channels involving na6He or 3n2α in the final state, with special emphasis dedicated in this contribution to the three-particle channel. The two emitted charged particles were detected in coincidence using a highly segmented experimental set-up. The observed experimental energy-vs-energy scatter plot indicates a sequential breakup where nuclei of mass 4, alpha particles, and mass 7, 7He, are involved. A Monte-Carlo simulation of the sequential channel, 11Be* → α + 7He → nα6He was performed and compared to the experimental data and to a simulation of the direct break-up of the 18.2 MeV state nα6He by phase space energy distribution. The energy-versus-energy plot are explained by the sequential simulation but not by the phase space simulation.
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| 12. |
- Mukha, I., et al.
(författare)
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Observation of the Li-11(beta d) decay
- 1996
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Ingår i: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 367:1-4, s. 65-69
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Tidskriftsartikel (refereegranskat)abstract
- Experimental data from the decay of Li-11 show for the first time the presence of beta-delayed deuterons with a branching ratio larger than 10(-4). To distinguish between beta d and beta t events the decays of the daughter nuclei Li-9 and Li-8 were identified in the energy and decay time spectra. Furthermore, a time correlation analysis between the beta d events and the subsequent daughter decays was performed.
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| 13. |
- Nilsson, Thomas, 1965, et al.
(författare)
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Neutron Momentum Distributions from Core Break-up Reactions of Halo Nuclei
- 1995
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Ingår i: Europhysics Letters. - 0295-5075 .- 1286-4854. ; 30:1, s. 19-24
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Tidskriftsartikel (refereegranskat)abstract
- Neutron angular distributions from violent break-up reactions of Li-11 and Be-11 have been measured at 28 MeV/u and 280 MeV/u and at 41 MeV/u and 460 MeV/u, respectively. The derived neutron momentum distributions show a narrow component in transverse momentum that is within uncertainties independent of beam energy and target charge. This component is suggested to be simply related to the momentum distribution of the loosely bound halo neutron(s) in the projectiles.
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| 14. |
- Oinonen, M., et al.
(författare)
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Non-analog beta decay of Rb-74
- 2001
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Ingår i: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - 0370-2693. ; 511:2-4, s. 145-150
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Tidskriftsartikel (refereegranskat)abstract
- The magnitude of the Coulomb mixing parameter delta (l)(IM) has been experimentally deduced, for the first time, for the B decay of Rb-74. Th, estimated magnitude is derived from the feeding of the non-analog first excited 0(+) state in Kr-74. The inferred upper Limit of 0.07% is small compared to theoretical predictions. The half-life was measured to be 64.90(9) ms.
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| 15. |
- Prezado, Y., et al.
(författare)
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Large asymmetry in the strongest beta-transition for A=9
- 2003
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Ingår i: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 576:1-2, s. 55-61
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Tidskriftsartikel (refereegranskat)abstract
- A new measurement of the beta-decay of Li-9 has clarified the feeding to the highest accessible states in Be-9. It is found that the P-decay mainly populates the 11.8 MeV state, whose spin is determined as 5/2(-). The extracted B-GT value of 5.3(0.9) is a factor 4.4(1.0) larger than that of the mirror transition from C-9. A theoretical explanation of such a pronounced beta-decay asymmetry is presently lacking. (C) 2003 Elsevier B.V. All rights reserved.
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| 16. |
- Shergur, J., et al.
(författare)
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beta-decay studies of Sn135-137 using selective resonance laser ionization techniques
- 2002
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Ingår i: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 65:3
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Tidskriftsartikel (refereegranskat)abstract
- The decays of the very neutron rich Sn isotopes Sn135-137 were studied at CERN/ISOLDE using isotopic and isobaric selectivity achieved by the use of a resonance ionization laser ion source and mass spectroscopy, respectively. Neutron decay rates, gamma-ray singles, and gamma-gamma coincidence data were collected as a function of time. The half-life (T-1/2) and delayed neutron emission probability (P-n) values of 135 Sn were measured to be 530(20) ms and 21(3)%, respectively. For Sn-136, a T-1/2 of 250(30) ms was determined along with a P-n value of 30(5)%. For Sn-137, a T-1/2 of 190(60) ms and a P-n value of 58(15)% were deduced. Identification of low-energy transitions in Sb-135 was made possible by comparison of laser-on and laser-off gamma-ray spectra. Those data combined with gamma-gamma coincidence spectra were used to construct a level scheme for Sb-135 that includes an unexpectedly low first excited state at 282 keV. A ground state beta branch of 33.2% was measured by following the growth and decay of the Sb-135 daughter. Shell-model calculations are consistent with the observed Sb-135 level structure and can account for a lowered first excited state.
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| 17. |
- Shergur, J., et al.
(författare)
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Decay of Sn-135,Sn-136 isolated by use of a laser ion source and evidence for a more harmonic-oscillator-like nuclear potential
- 2001
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Ingår i: Nuclear Physics A. - 0375-9474. ; 682, s. 493C-497C
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Konferensbidrag (refereegranskat)abstract
- The use of a resonance ionization laser ion source at CERN/ISOLDE has made it possible to study the decay of very neutron-rich Sn135-137. The decay of Sn-135 is found to populate low-energy levels in Sb-135 via direct beta decay and the first excited state in Sb-134 by beta-delayed neutron emission. The level structure of Sb-135 Will be discussed and a possible signature for a more diffuse nuclear surface considered.
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| 18. |
- Wilhelmsen Rolander, Katarina, 1962
(författare)
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Neutron Halo Nuclei
- 1993
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In light nuclei close to the neutron drip-line a spatially extended neutron distribution, the neutron, halo occurs. This is due to the relatively small binding energy of the last neutrons which makes possible quantum mechanical tunnelling of the last neutron(s) far away from the nuclear core. There are two main paths in the experimental study of the structure of these nuclei: reactions with radioactive nuclear beams and beta-decays. In reaction studies the momentum distributions from the fragments of reactions between halo nuclei and targets are studied. Results from measurements of (mainly) neutrons from the break-up of the two-neutron halo nucleus 11Li and 11Be with a single neutron halo are presented here. For 11Li data from reactions at 29 MeV/B on three different targets Be, Ni and Au are shown. All the angular distributions of the neutrons are narrow. In reactions of 41 MeV/B 11Be it is clearly seen that different reaction mechanisms are present for different charge of the target. For low Z targets nuclear dissociation reactions dominate yielding board neutron distributions. For targets with high proton number the main contributions is Coulomb dissociation, giving narrow angular distributions. A systematic trend in the .beta.-decay of drip-line nuclei is very large beta-feeding to highly excited states in the daughter nuclei. When states above the separation energy of one or several nucleons are fed, beta-delayed particle emission will occur. Energy spectra of .beta.-delayed particles are analysed to yield information about nuclear structure. In this work is presented experimental data about beta-delayed charged particles, emitted in the decays of 6,8He and 11Li. In the decay of 6He .beta.-delayed deuteron emission was identified for the first time. For 8He and 11Li new data concerning the triton branching ratios are presented. It is also shown that there could be a branch of. beta.-delayed deuterons present in the decay of 11Li , which might be interpreted as the peripheral beta-decay of the two neutron halo.
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