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- Elekes, Z., et al.
(author)
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Shape coexistence in 66Se
- 2023
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In: Physics Letters B. - : Elsevier. - 0370-2693 .- 1873-2445. ; 844
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Journal article (peer-reviewed)abstract
- The nuclear structure of 66Se, nucleus beyond the N=Z line on the proton-rich side of the valley of stability, was investigated by the neutron knock-out reaction 67Se(12C,X)66Se using a 12C target. The analysis of the singles spectrum of the γ-rays emitted during the de-excitation of the populated low-lying excited states revealed two previously detected (927(4) keV, 1460(32) keV) and three new (744(6) keV, 1210(17) keV, 1661(23) keV) transitions. The 744-keV, the 1210-keV, and the 1460-keV transitions were found to be in coincidence with the one at 927 keV. The spectrum coincident with the 927-keV transition showed a further possible transition at 299(35) keV, which was obscured by significant atomic background in the singles spectrum. This transition might correspond to a peak previously reported at 273(5) keV that could not be assigned to 66Se unambiguously. Based on a comparison of the experimental data to theoretical calculations, four new excited states are proposed which suggest that 66Se exhibits shape coexistence.
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| 2. |
- Storck, Sonja, et al.
(author)
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Lifetime measurement of the 26 0 g.s. At SAMURAI
- 2020
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In: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 1643:1
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Conference paper (peer-reviewed)abstract
- The ground state of the neutron unbound nucleus O is speculated to have a lifetime in the pico-second regime. In order to determine the decay lifetime of the O ground state with high sensitivity and precision, a new method has been applied. The experiment was performed in December 2016 at the Superconducting Analyzer for MUlti-particle from Radio Isotope Beams (SAMURAI) at the Radioactive Isotope Beam Factory (RIBF) at RIKEN. A F beam was produced in the fragment separator BigRIPS and impinged on a W/Pt target stack where O was produced. According to the lifetime, the decay of O happens either in or outside the target. Thus, the velocity difference between the decay neutrons and the fragment O delivers a characteristic spectrum from which the lifetime can be extracted.
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| 3. |
- Duer, M., et al.
(author)
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Observation of a correlated free four-neutron system
- 2022
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In: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 606:7915
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Journal article (peer-reviewed)abstract
- A long-standing question in nuclear physics is whether chargeless nuclear systems can exist. To our knowledge, only neutron stars represent near-pure neutron systems, where neutrons are squeezed together by the gravitational force to very high densities. The experimental search for isolated multi-neutron systems has been an ongoing quest for several decades(1), with a particular focus on the four-neutron system called the tetraneutron, resulting in only a few indications of its existence so far(2-4), leaving the tetraneutron an elusive nuclear system for six decades. Here we report on the observation of a resonance-like structure near threshold in the four-neutron system that is consistent with a quasi-bound tetraneutron state existing for a very short time. The measured energy and width of this state provide a key benchmark for our understanding of the nuclear force. The use of an experimental approach based on a knockout reaction at large momentum transfer with a radioactive high-energy He-8 beam was key.
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| 8. |
- Gyürky, Gy., et al.
(author)
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Resonance strengths in the 14N( p,γ)15O astrophysical key reaction measured with activation
- 2019
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In: Physical Review C. - : American Physical Society. - 2469-9985 .- 2469-9993. ; 100:1
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Journal article (peer-reviewed)abstract
- Background: The 14N(p,γ)15O reaction plays a vital role in various astrophysical scenarios. Its reaction rate must be accurately known in the present era of high precision astrophysics. The cross section of the reaction is often measured relative to a low energy resonance, the strength of which must therefore be determined precisely.Purpose: The activation method, based on the measurement of 15O decay, has not been used in modern measurements of the 14N(p,γ)15O reaction. The aim of the present work is to provide strength data for two resonances in the 14N(p,γ)15O reaction using the activation method. The obtained values are largely independent from previous data measured by in-beam γ spectroscopy and are free from some of their systematic uncertainties.Method: Solid state TiN targets were irradiated with a proton beam provided by the Tandetron accelerator of Atomki using a cyclic activation. The decay of the produced 15O isotopes was measured by detecting the 511 keV positron annihilation γ rays.Results: The strength of the Ep=278keV resonance was measured to be ωγ278=(13.4±0.8)meVwhile for the Ep=1058keV resonance ωγ1058=(442±27)meV.Conclusions: The obtained Ep=278 keV resonance strength is in fair agreement with the values recommended by two recent works. However, the Ep=1058keV resonance strength is about 20% higher than the previous value. The discrepancy may be caused in part by a previously neglected finite target thickness correction. As only the low energy resonance is used as a normalization point for cross section measurements, the calculated astrophysical reaction rate of the 14N(p,γ)15O reaction and therefore the astrophysical consequences are not changed by the present results.
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| 9. |
- Halasz, R, et al.
(author)
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Relation between GB virus C/hepatitis G virus and fulminant hepatic failure may be secondary to treatment with contaminated blood and/or blood products
- 1999
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In: Gut. - : BMJ. - 0017-5749 .- 1468-3288. ; 44:2, s. 274-278
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Journal article (peer-reviewed)abstract
- The role of the recently discovered GB virus C (GBV-C)/hepatitis G virus in fulminant hepatic failure (FHF) has been debated. Although GBV-C RNA has been detected in many cases of FHF, recent data suggest that the relation between GBV-C and FHF may be accidental.AimsTo retrospectively investigate the possible relation between the presence of GBV-C markers (RNA or antibodies to the GBV-C envelope 2 (E2) glycoprotein) and FHF.MethodsThe presence of GBV-C RNA was determined in serum samples from 58 patients diagnosed with FHF using a reverse transcriptase polymerase chain reaction. Amplified genetic fragments were directly sequenced by the dideoxy chain termination method. Antibodies to GBV-C in serum samples were detected by enzyme immunoassay based on a recombinant GBV-C E2 protein.ResultsNine (16%) patients with FHF had GBV-C RNA and 14 (24%) had GBV-C E2 antibodies, which are higher frequencies than in healthy subjects (p<0.01 and p<0.05 respectively). Seven of ten patients with GBV-C markers during FHF tested negative for these markers before therapy with blood and/or blood products. Sequence analysis of the GBV-C NS3 region fragments of six FHF patients showed no common sequence pattern or motif.ConclusionsThe frequencies of both GBV-C RNA and antibodies are higher in patients with FHF than in healthy subjects. However, these increased frequencies may in many cases be explained by the use of contaminated blood and/or blood products given as therapy.
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