| 1. |
- Jentschel, M., et al.
(författare)
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EXILL - a high-efficiency, high-resolution setup for gamma-spectroscopy at an intense cold neutron beam facility
- 2017
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Ingår i: Journal of Instrumentation. - : IOP PUBLISHING LTD. - 1748-0221. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- In the EXILL campaign a highly efficient array of high purity germanium (HPGe) detectors was operated at the cold neutron beam facility PF1B of the Institut Laue-Langevin (ILL) to carry out nuclear structure studies, via measurements of gamma-rays following neutron-induced capture and fission reactions. The setup consisted of a collimation system producing a pencil beam with a thermal capture equivalent flux of about 10(8) ns(-1)cm(2) at the target position and negligible neutron halo. The targetwas surrounded by an array of eight to ten anti-Compton shielded EXOGAMClover detectors, four to six anti-Compton shielded large coaxial GASP detectors and two standard Clover detectors. For a part of the campaign the array was combined with 16 LaBr3:(Ce) detectors from the FATIMA collaboration. The detectorswere arranged in an array of rhombicuboctahedron geometry, providing the possibility to carry out very precise angular correlation and directional-polarization correlation measurements. The triggerless acquisition system allowed a signal collection rate of up to 6 x 10(5) Hz. The data allowed to set multi-fold coincidences to obtain decay schemes and in combination with the FATIMA array of LaBr3:(Ce) detectors to analyze half-lives of excited levels in the pico-to microsecond range. Precise energy and efficiency calibrations of EXILL were performed using standard calibration sources of Ba-133, Co-60 and Eu-152 as well as data from the reactions Al-27(n, gamma)Al-28 and Cl-35(n,gamma)Cl-36 in the energy range from 30 keV up to 10MeV.
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| 2. |
- Caciolli, A., et al.
(författare)
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Revision of the 15N(p, γ)16O reaction rate and oxygen abundance in H-burning zones
- 2011
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 533
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Tidskriftsartikel (refereegranskat)abstract
- Context. The NO cycle takes place in the deepest layer of a H-burning core or shell, when the temperature exceeds T ≈ 30 × 106 K. The O depletion observed in some globular cluster giant stars, always associated with a Na enhancement, may be due to either a deep mixing during the red giant branch (RGB) phase of the star or to the pollution of the primordial gas by an early population of massive asymptotic giant branch (AGB) stars, whose chemical composition was modified by the hot bottom burning. In both cases, the NO cycle is responsible for the O depletion. Aims. The activation of this cycle depends on the rate of the 15N(p, γ)16O reaction. A precise evaluation of this reaction rate at temperatures as low as experienced in H-burning zones in stellar interiors is mandatory to understand the observed O abundances. Methods. We present a new measurement of the 15N(p, γ)16O reaction performed at LUNA covering for the first time the center of mass energy range 70-370 keV, which corresponds to stellar temperatures between 65 × 106 K and 780 × 106 K. This range includes the 15N(p, γ)16O Gamow-peak energy of explosive H-burning taking place in the external layer of a nova and the one of the hot bottom burning (HBB) nucleosynthesis occurring in massive AGB stars. Results. With the present data, we are also able to confirm the result of the previous R-matrix extrapolation. In particular, in the temperature range of astrophysical interest, the new rate is about a factor of 2 smaller than reported in the widely adopted compilation of reaction rates (NACRE or CF88) and the uncertainty is now reduced down to the 10% level. © 2011 ESO.
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| 3. |
- Marta, M., et al.
(författare)
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Precision study of ground state capture in the 14N(p,γ)15O reaction
- 2008
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 78:2
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Tidskriftsartikel (refereegranskat)abstract
- The rate of the hydrogen-burning carbon-nitrogen-oxygen (CNO) cycle is controlled by the slowest process, 14N(p,γ)15O, which proceeds by capture to the ground and several excited states in O15. Previous extrapolations for the ground state contribution disagreed by a factor 2, corresponding to 15% uncertainty in the total astrophysical S factor. At the Laboratory for Underground Nuclear Astrophysics (LUNA) 400 kV accelerator placed deep underground in the Gran Sasso facility in Italy, a new experiment on ground state capture has been carried out at 317.8, 334.4, and 353.3 keV center-of-mass energy. Systematic corrections have been reduced considerably with respect to previous studies by using a Clover detector and by adopting a relative analysis. The previous discrepancy has been resolved, and ground state capture no longer dominates the uncertainty of the total S factor. © 2008 The American Physical Society.
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| 4. |
- Marta, M., et al.
(författare)
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The N14(p,γ)O15 reaction studied with a composite germanium detector
- 2011
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 83:4
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Tidskriftsartikel (refereegranskat)abstract
- The rate of the carbon-nitrogen-oxygen (CNO) cycle of hydrogen burning is controlled by the N14(p,γ)O15 reaction. The reaction proceeds by capture to the ground states and several excited states in O15. In order to obtain a reliable extrapolation of the excitation curve to astrophysical energy, fits in the R-matrix framework are needed. In an energy range that sensitively tests such fits, new cross-section data are reported here for the four major transitions in the N14(p,γ)O15 reaction. The experiment has been performed at the Laboratory for Underground Nuclear Astrophysics (LUNA) 400-kV accelerator placed deep underground in the Gran Sasso facility in Italy. Using a composite germanium detector, summing corrections have been considerably reduced with respect to previous studies. The cross sections for capture to the ground state and to the 5181, 6172, and 6792 keV excited states in O15 have been determined at 359, 380, and 399 keV beam energy. In addition, the branching ratios for the decay of the 278-keV resonance have been remeasured. © 2011 American Physical Society.
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| 5. |
- Santoro, Aurelia, et al.
(författare)
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Combating inflammaging through a Mediterranean whole diet approach : The NU-AGE project's conceptual framework and design
- 2014
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Ingår i: Mechanisms of Ageing and Development. - Clare, Ireland : Elsevier BV. - 0047-6374 .- 1872-6216. ; 136-137, s. 3-13
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Tidskriftsartikel (refereegranskat)abstract
- The development of a chronic, low grade, inflammatory status named "inflammaging" is a major characteristic of ageing, which plays a critical role in the pathogenesis of age-related diseases. Inflammaging is both local and systemic, and a variety of organs and systems contribute inflammatory stimuli that accumulate lifelong. The NU-AGE rationale is that a one year Mediterranean whole diet (considered by UNESCO a heritage of humanity), newly designed to meet the nutritional needs of the elderly, will reduce inflammaging in fully characterized subjects aged 65-79 years of age, and will have systemic beneficial effects on health status (physical and cognitive). Before and after the dietary intervention a comprehensive set of analyses, including omics (transcriptomics, epigenetics, metabolomics and metagenomics) will be performed to identify the underpinning molecular mechanisms. NU-AGE will set up a comprehensive database as a tool for a systems biology approach to inflammaging and nutrition. NU-AGE is highly interdisciplinary, includes leading research centres in Europe on nutrition and ageing, and is complemented by EU multinational food industries and SMEs, interested in the production of functional and enriched/advanced traditional food tailored for the elderly market, and European Federations targeting policy makers and major stakeholders, from consumers to EU Food & Drink Industries.
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| 6. |
- Trautvetter, H P, et al.
(författare)
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Ground state capture in 14N(p,γ)15O studied above the 259 keV resonance at LUNA
- 2008
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Ingår i: Journal of Physics G. - : IOP Publishing. - 0954-3899 .- 1361-6471. ; 35:1
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Tidskriftsartikel (refereegranskat)abstract
- We report on a new measurement of 14N(p,γ)15O for the ground state capture transition at Ep = 360, 380 and 400 keV, using the 400 kV LUNA accelerator. The true coincidence summing effect - the major source of error in the ground state capture determination - has been significantly reduced by using a Clover-type gamma detector. © 2008 IOP Publishing Ltd.
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| 7. |
- Grigorenko,, et al.
(författare)
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Deep excursion beyond the proton dripline. II. Toward the limits of existence of nuclear structure
- 2018
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Ingår i: Physical Review C. - 2469-9985 .- 2469-9993. ; 98:6
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Tidskriftsartikel (refereegranskat)abstract
- Prospects of experimental studies of argon and chlorine isotopes located far beyond the proton dripline are studied by using systematics and cluster models. The deviations from the widespread systematics observed in Cl-28,Cl-29 and Ar-29,Ar-30 have been theoretically substantiated, and analogous deviations have been predicted for the lighter chlorine and argon isotopes. The limits of nuclear structure existence are predicted for Ar and Cl isotopic chains, with Ar-26 and Cl-25 found to be the lightest sufficiently long-living nuclear systems. By simultaneous measurements of protons and gamma rays following decays of such systems as well as their beta-delayed emission, an interesting synergy effect may be achieved, which is demonstrated by the example of Cl-30 and Ar-31 ground-state studies. Such a synergy effect may be provided by the new EXPERT setup (EXotic Particle Emission and Radioactivity by Tracking) being operated inside the fragment separator and spectrometer facility at GSI, Darmstadt.
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| 8. |
- Kostyleva, D., et al.
(författare)
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Towards the Limits of Existence of Nuclear Structure: Observation and First Spectroscopy of the Isotope K-31 by Measuring Its Three-Proton Decay
- 2019
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Ingår i: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 123:9
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Tidskriftsartikel (refereegranskat)abstract
- The most remote isotope from the proton dripline (by 4 atomic mass units) has been observed: K-31. It is unbound with respect to three-proton (3p) emission, and its decays have been detected in flight by measuring the trajectories of all decay products using microstrip detectors. The 3p emission processes have been studied by the means of angular correlations of S-28 + 3p and the respective decay vertices. The energies of the previously unknown ground and excited states of K-31 have been determined. This provides its 3p separation energy value S-3p of -4.6(2) MeV. Upper half-life limits of 10 ps of the observed K-31 states have been derived from distributions of the measured decay vertices.
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| 9. |
- Marroquin, I., et al.
(författare)
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MULTI-PARTICLE EMISSION FROM Ar-31 AT ISOLDE
- 2016
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Ingår i: Acta Physica Polonica, Series B.. - 1509-5770 .- 0587-4254. ; 47:3, s. 747-754
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Tidskriftsartikel (refereegranskat)abstract
- A multi-particle decay experiment was successfully performed at the ISOLDE Decay Station. In this new permanent station, devoted to beta-decay studies, the novel MAGISOL Si-Plugin Chamber was installed to study the exotic decay modes of the proton drip-line nucleus Ar-31. The motivation was to search for beta 3p and beta 3p gamma channels, as well as to provide information on resonances in S-30 and P-29 relevant for the astrophysical rp-process. Description of the experimental set-up and preliminary results are presented.
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| 10. |
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| 11. |
- Mineva, Milena, et al.
(författare)
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A New us Isomer in 136Sb Produced in the Projectile Fission of 238U
- 2001
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Ingår i: European Physical Journal A. Hadrons and Nuclei. - 1434-6001. ; 11, s. 9-13
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Tidskriftsartikel (refereegranskat)abstract
- The neutron-rich isotope Sb-136 has been produced following the relativistic projectile fission of U-238 in an experiment performed at the Fragment Separator at GSI, Darmstadt. Delayed gamma -ray spectroscopy of the fission products has been performed after isotope separation. A new isomeric state in Sb-136 has been populated, and its lifetime measured as T-1/2 = 565(50) ns. Realistic and empirical shell-model calculations have been performed and are compared to the experimental observables.
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| 12. |
- Mukha, I. G., et al.
(författare)
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Deep excursion beyond the proton dripline. I. Argon and chlorine isotope chains
- 2018
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Ingår i: Physical Review C. - 2469-9993 .- 2469-9985. ; 98:6
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Tidskriftsartikel (refereegranskat)abstract
- The proton-unbound argon and chlorine isotopes have been studied by measuring trajectories of their decay-in-flight products by using a tracking technique with microstrip detectors. The proton (1p) and two-proton (2p) emission processes have been detected in the measured angular correlations "heavy-fragment"+p and "heavy-fragment"+p+p, respectively. The ground states of the previously unknown isotopes Cl30 and Cl28 have been observed for the first time, providing the 1p-separation energies Sp of -0.48(2) and -1.60(8), MeV, respectively. The relevant systematics of 1p- and 2p-separation energies have been studied theoretically in the core+p and core+p+p cluster models. The first-time observed excited states of Ar31 allow one to infer the 2p-separation energy S2p of 6(34) keV for its ground state. The first-time observed state in Ar29 with S2p=-5.50(18) MeV can be identified as either a ground state or an excited state according to different systematics.
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| 13. |
- Mukha, I., et al.
(författare)
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Observation and Spectroscopy of New Proton-Unbound Isotopes Ar-30 and Cl-29: An Interplay of Prompt Two-Proton and Sequential Decay
- 2015
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Ingår i: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 115:20, s. 7-
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Tidskriftsartikel (refereegranskat)abstract
- Previously unknown isotopes Ar-30 and Cl-29 have been identified by measurement of the trajectories of their in-flight decay products S-28 + p + p and S-28 + p, respectively. The analysis of angular correlations of the fragments provided information on decay energies and the structure of the parent states. The ground states of Ar-30 and Cl-29 were found at 2.25(-0.10)(+0.15) and 1.8 +/- 0.1 MeV above the two-and one-proton thresholds, respectively. The lowest states in Ar-30 and Cl-29 point to a violation of isobaric symmetry in the structure of these unbound nuclei. The two-proton decay has been identified in a transition region between simultaneous two-proton and sequential proton emissions from the Ar-30 ground state, which is characterized by an interplay of three-body and two-body decay mechanisms. The first hint of a fine structure of the two-proton decay of Ar-30*(2(+)) has been obtained by detecting two decay branches into the ground and first-excited states of the S-28 fragment.
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| 14. |
- Gadea, A, et al.
(författare)
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Hindered E4 decay of the 12(+) yrast trap in Fe-52
- 2005
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Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 619:1-2, s. 88-94
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Tidskriftsartikel (refereegranskat)abstract
- The gamma decay of the 12(+) yrast trap in Fe-52 has been measured for the first time. The two E4 gamma-branches to the 8(+) states are hindered with respect to other B(E4) reduced transition probabilities measured in the f(7/2) shell. The interpretation of the data is given in the full pf shell model framework, comparing the results obtained with different residual interactions. It is shown that measurements of hexadecapole transition probabilities constitute a powerful tool in discriminating the correct configuration of the involved wavefunctions.
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| 15. |
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| 16. |
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| 17. |
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| 18. |
- Janiak, M., et al.
(författare)
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β -delayed proton emission from P 26 and S 27
- 2017
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Ingår i: Physical Review C: covering nuclear physics. - 2469-9985. ; 95:3
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Tidskriftsartikel (refereegranskat)abstract
- Delayed emission of protons following β decay of neutron deficient nuclei P26 and S27 was investigated at the ACCULINNA separator in the Flerov Laboratory of Nuclear Reactions at Dubna. Ions of interest, identified in flight, were implanted into the active volume of the gaseous optical time projection chamber, which allowed us to record tracks of charged particles emitted in the decay. Total branching ratios for β-delayed proton emission and for β-delayed two-proton emission were determined. In addition, energy spectra for delayed protons below 2 MeV were established. Our findings for P26 agree with results of previous experiments. In the case of S27, however, the observed probability of delayed proton emission is an order of magnitude larger than reported in literature. Two new strong proton transitions were identified representing decays of the first two excited states of P27 to the ground state of Si26. The probability ratio of γ-to-proton emission from these states is discussed.
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