| 11. |
- Koldste, G. T., et al.
(author)
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Multiparticle emission in the decay of Ar-31
- 2014
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In: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 89:6
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Journal article (peer-reviewed)abstract
- A multihit capacity setup was used to study the decay of the dripline nucleus Ar-31, produced at the ISOLDE facility at CERN. A spectroscopic analysis of the beta-delayed three-proton decay of Ar-31 is presented for the first time together with a quantitative analysis of the beta-delayed 2p gamma decay. A new method for determination of the spin of low-lying levels in the beta p daughter 30S using proton-proton angular correlations is presented and used to determine that the spin of the 5.2-MeV level is most likely 3(+) with 4(+) also possible. The half-life of Ar-31 is found to be 15.1(3) ms. An improved analysis of the Fermi beta strength including the beta 3p-decay mode gives a total measured branching ratio of 3.60(44)%, which is lower than the theoretical value found to be 4.24(43)%. Finally, a previously unidentified. transition from the isobaric analog state in the decay of Ar-33 has been found.
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| 12. |
- Cortina-Gil, D., et al.
(author)
-
CALIFA, a Dedicated Calorimeter for the R3B/FAIR
- 2014
-
In: Nuclear Data Sheets. - : Elsevier BV. - 1095-9904 .- 0090-3752. ; 120, s. 99-101
-
Journal article (peer-reviewed)abstract
- The R3B experiment (Reactions with Relativistic Radioactive Beams) at FAIR (Facility for Antiproton and Ion Research) is a versatile setup dedicated to the study of reactions induced by high-energy radioactive beams. It will provide kinematically complete measurements with high efficiency, acceptance and resolution, making possible a broad physics program with rare-isotopes. CALIFA (CALorimeter for In-Flight detection of gamma-rays and high energy charged pArticles), is a complex detector based on scintillation crystals, that will surround the target of the R3B experiment. CALIFA will act as a total absorption gamma-calorimeter and spectrometer, as well as identifier of charged particles from target residues. This versatility is its most challenging requirement, demanding a huge dynamic range, to cover from low energy gamma-rays up to 300 MeV protons. This fact, along with the high-energy of the beams determine the conceptual design of the detector, presented in this paper, together with the technical solutions proposed for its construction.
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| 13. |
- Koldste, G. T., et al.
(author)
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Relative proton and gamma widths of astrophysically important states in S-30 studied in the beta-delayed decay of Ar-31
- 2013
-
In: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 87:5
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Journal article (peer-reviewed)abstract
- Resonances just above the proton threshold in S-30 affect the P-29(p, gamma)S-30 reaction under astrophysical conditions. The (p,gamma)-reaction rate is currently determined indirectly and depends on the properties of the relevant resonances. We present here a method for finding the ratio between the proton and gamma partial widths of resonances in S-30. The widths are determined from the beta 2p- and beta p gamma-decay of Ar-31, which is produced at the ISOLDE radioactive ion beam facility at the European research organization CERN. Experimental limits on the ratio between the proton and gamma partial widths for astrophysical relevant levels in S-30 have been found for the first time. A level at 4689.2(24) keV is identified in the gamma spectrum, and an upper limit on the Gamma(p)/ Gamma gamma ratio of 0.26 (95% C.L.) is found. In the two-proton spectrum two levels at 5227(3) keV and 5847(4) keV are identified. These levels were previously seen to gamma decay and upper limits on the Gamma(gamma)/Gamma(p) ratio of 0.5 and 9, respectively, (95% C.L.) are found, where the latter differs from previous calculations.
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| 14. |
- Koldste, G. T., et al.
(author)
-
Sizeable beta-strength in Ar-31 (beta 3p) decay
- 2014
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In: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 737, s. 383-387
-
Journal article (peer-reviewed)abstract
- We present for the first time precise spectroscopic information on the recently discovered decay mode beta-delayed 3p-emission. The detection of the 3p events gives an increased sensitivity to the high energy part of the Gamow-Teller strength distribution from the decay of Ar-31 revealing that as much as 30% of the strength resides in the beta 3p-decaymode. A simplified description of how the main decay modes evolve as the excitation energy increases in Cl-31 is provided.
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| 15. |
- Wamers, F., et al.
(author)
-
First Observation of the Unbound Nucleus Ne-15
- 2014
-
In: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 112:13
-
Journal article (peer-reviewed)abstract
- We report on the first observation of the unbound proton-rich nucleus Ne-15. Its ground state and first excited state were populated in two-neutron knockout reactions from a beam of 500 MeV/u Ne-17. The Ne-15 ground state is found to be unbound by 2.522(66) MeV. The decay proceeds directly to O-13 with simultaneous two-proton emission. No evidence for sequential decay via the energetically allowed 2(-) and 1(-) states in F-14 is observed. The Ne-15 ground state is shown to have a strong configuration with two protons in the (sd) shell around O-13 with a 63(5)% (1s(1/2))(2) component.
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| 16. |
- Hyldegaard, S., et al.
(author)
-
R-matrix analysis of the beta decays of 12N and 12B
- 2010
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In: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 81:2
-
Journal article (peer-reviewed)abstract
- The β decays of 12N and 12B have been studied at KVI and JYFL to resolve the composition of the broad and interfering 0+ and 2+ strengths in the triple-α continuum. For the first time a complete treatment of 3α decay is presented including all major breakup channels. A multilevel, many-channel R-matrix formalism has been developed for the complete description of the breakup in combination with the recently published separate analysis of angular correlations. We find that, in addition to the Hoyle state at 7.65 MeV, more than one 0+ and 2+ state is needed to reproduce the spectra. Broad 03+ and 22+ states are found between 10.5 and 12 MeV in this work. The presence of β strength up to the 12N Q-value window suggests the presence of additional 0+ and 2+ components in the 12C structure at energies above 12.7 MeV.
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| 17. |
- Johansen, J. G., et al.
(author)
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Experimental study of bound states in Be-12 through low-energy Be-11(d,p)-transfer reactions
- 2013
-
In: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 88:4
-
Journal article (peer-reviewed)abstract
- The bound states of Be-12 have been studied through a Be-11(d, p) Be-12 transfer reaction experiment in inverse kinematics. A 2.8 MeV/u beam of Be-11 was produced using the REX-ISOLDE facility at CERN. The outgoing protons were detected with the T-REX silicon detector array. The MINIBALL germanium array was used to detect gamma rays from the excited states in Be-12. The gamma-ray detection enabled a clear identification of the four known bound states in Be-12, and each of the states has been studied individually. Differential cross sections over a large angular range have been extracted. Spectroscopic factors for each of the states have been determined from distorted wave Born approximation (DWBA) calculations and have been compared to previous experimental and theoretical results.
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| 18. |
- Kirsebom, O. S., et al.
(author)
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Precise and accurate determination of the B-8 decay spectrum
- 2011
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In: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 83:6
-
Journal article (peer-reviewed)abstract
- Accurate measurements of the B-8 neutrino spectrum are important for the interpretation of solar neutrino data. Experimentally, the B-8 neutrino spectrum can be obtained from the measurement of the beta-delayed alpha spectrum. We report on an alpha-alpha coincidence measurement performed at the IGISOL facility in Jyvaskyla, Finland. Our measurement allows extensive cross-checks to be performed and gives a more intense neutrino spectrum at high energies compared to the present standard. The deviation reaches 4% at the end point of the spectrum. Below 11 MeV, the deviation is less than 1%.
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| 19. |
- Marganiec, C., et al.
(author)
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Coulomb breakup of 17Ne from the viewpoint of nuclear astrophysics
- 2013
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In: Proceedings of Science.
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Conference paper (peer-reviewed)abstract
- By the Coulomb breakup of 17Ne, the time-reversed reaction 15O(2p,γ)17Ne has been studied. This reaction might play an important role in the rp process, as a break-out reaction of the hot CNO cycle. The secondary 17Ne ion beam with an energy of 500 MeV/nucleon has been dissociated in a Pb target. The reaction products have been detected with the LAND-R3B experimental setup at GSI. The preliminary differential and integral Coulomb dissociation cross section sCoul has been determined, which then will be converted into a photo-absorption cross section sphot o, and a two-proton radiative capture cross section σcap. Additionally, information about the structure of the 17Ne, a potential two-proton halo nucleus, will be received. The analysis is in progress.
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| 20. |
- Riisager, K., et al.
(author)
-
Be-11(beta p), a quasi-free neutron decay?
- 2014
-
In: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 732, s. 305-308
-
Journal article (peer-reviewed)abstract
- We have observed beta(-)-delayed proton emission from the neutron-rich nucleus Be-11 by analyzing a sample collected at the ISOLDE facility at CERN with accelerator mass spectrometry (AMS). With a branching ratio of (8.3 +/- 0.9). 10(-6) the strength of this decay mode, as measured by the B-GT-value, is unexpectedly high. The result is discussed within a simple single-particle model and could be interpreted as a quasi-free decay of the Be-11 halo neutron into a single-proton state.
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