| 1. |
|
|
| 2. |
- Murari, A., et al.
(författare)
-
A control oriented strategy of disruption prediction to avoid the configuration collapse of tokamak reactors
- 2024
-
Ingår i: Nature Communications. - 2041-1723 .- 2041-1723. ; 15:1
-
Tidskriftsartikel (refereegranskat)abstract
- The objective of thermonuclear fusion consists of producing electricity from the coalescence of light nuclei in high temperature plasmas. The most promising route to fusion envisages the confinement of such plasmas with magnetic fields, whose most studied configuration is the tokamak. Disruptions are catastrophic collapses affecting all tokamak devices and one of the main potential showstoppers on the route to a commercial reactor. In this work we report how, deploying innovative analysis methods on thousands of JET experiments covering the isotopic compositions from hydrogen to full tritium and including the major D-T campaign, the nature of the various forms of collapse is investigated in all phases of the discharges. An original approach to proximity detection has been developed, which allows determining both the probability of and the time interval remaining before an incoming disruption, with adaptive, from scratch, real time compatible techniques. The results indicate that physics based prediction and control tools can be developed, to deploy realistic strategies of disruption avoidance and prevention, meeting the requirements of the next generation of devices.
|
|
| 3. |
|
|
| 4. |
|
|
| 5. |
- Beceiro-Novo, S., et al.
(författare)
-
Coulomb dissociation of 27 P: A reaction of astrophysical interest
- 2010
-
Ingår i: Proceedings of Science. - Trieste, Italy : Sissa Medialab. - 1824-8039. ; 100
-
Konferensbidrag (refereegranskat)abstract
- The ground-state decay of 26Al(0+) (T 1/2=1.05× 106) has a shorter life-time than the Universe. The presence of this element in the Galaxy was measured via g-ray spectroscopy, showing that the nucleosynthesis of this element is an ongoing process in stars. The proton-capture reaction 26Si(p,γ) 27P competes with the production of 26Al(0+) by β-decay. Coulomb dissociation of 27P has been suggested as an indirect method to measure radiative-proton capture when the direct reaction is not feasible. Such an experiment was performed at GSI with a secondary 27P beam produced by fragmenting a 36Ar primary beam at 500 A MeV. Two main observables are preliminarily presented in this work: the reaction cross section and the relative-energy spectrum of the outgoing fragments © Copyright owned by the author(s).
|
|
| 6. |
- Marganiec, J., et al.
(författare)
-
Coulomb Dissociation experiment of 27P
- 2015
-
Ingår i: Acta Physica Polonica, Series B.. - 1509-5770 .- 0587-4254. ; 46:3, s. 473-476
-
Tidskriftsartikel (refereegranskat)abstract
- The 26Si(p; γ)27P reaction, which might play an important role in the rp process, was studied by the Coulomb Dissociation method. The experiment was performed at GSI, Darmstadt. A secondary 27P ion beam of 500 MeV/nucleon was directed onto a Pb target. From this experiment, the Coulomb Dissociation cross section, σCoulex, will be deduced and then converted to the photoabsorption cross section, σphoto, and the radiativecapture cross section, σcap. Also information on the structure of 27P will be obtained. The analysis is in progress.
|
|
| 7. |
- Andersson, Per A., et al.
(författare)
-
Anger and disgust shape judgments of social sanctions across cultures, especially in high individual autonomy societies
- 2024
-
Ingår i: Scientific Reports. - : Nature Research. - 2045-2322. ; 14:1
-
Tidskriftsartikel (refereegranskat)abstract
- When someone violates a social norm, others may think that some sanction would be appropriate. We examine how the experience of emotions like anger and disgust relate to the judged appropriateness of sanctions, in a pre-registered analysis of data from a large-scale study in 56 societies. Across the world, we find that individuals who experience anger and disgust over a norm violation are more likely to endorse confrontation, ostracism and, to a smaller extent, gossip. Moreover, we find that the experience of anger is consistently the strongest predictor of judgments of confrontation, compared to other emotions. Although the link between state-based emotions and judgments may seem universal, its strength varies across countries. Aligned with theoretical predictions, this link is stronger in societies, and among individuals, that place higher value on individual autonomy. Thus, autonomy values may increase the role that emotions play in guiding judgments of social sanctions.
|
|
| 8. |
- Caciolli, A., et al.
(författare)
-
Revision of the 15N(p, γ)16O reaction rate and oxygen abundance in H-burning zones
- 2011
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 533
-
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.
|
|
| 9. |
- Formicola, A, et al.
(författare)
-
Astrophysical S-factor of 14N(p,γ)15O
- 2004
-
Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 591:1-2, s. 61-68
-
Tidskriftsartikel (refereegranskat)abstract
- We report on a new measurement of the 14N(p,γ) 15O capture cross section at Ep=140 to 400 keV using the 400 kV LUNA accelerator facility at the Laboratori Nazionali del Gran Sasso (LNGS). The uncertainties have been reduced with respect to previous measurements and their analysis. We have analyzed the data using the R-matrix method and we find that the ground state transition accounts for about 15% of the total S-factor. The main contribution to the S-factor is given by the transition to the 6.79 MeV state. We find a total S(0)=1.7±0.2 keVb, in agreement with recent extrapolations. The result has important consequences for the solar neutrino spectrum as well as for the age of globular clusters. © 2004 Elsevier B.V. All rights reserved.
|
|
| 10. |
- Gobel, K., et al.
(författare)
-
Coulomb dissociation of 16O into 4He and 12C
- 2020
-
Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 1668:1
-
Konferensbidrag (refereegranskat)abstract
- We measured the Coulomb dissociation of 16O into 4He and 12C at the R3B setup in a first campaign within FAIR Phase 0 at GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt. The goal was to improve the accuracy of the experimental data for the 12C(a,?)16O fusion reaction and to reach lower center-ofmass energies than measured so far. The experiment required beam intensities of 109 16O ions per second at an energy of 500 MeV/nucleon. The rare case of Coulomb breakup into 12C and 4He posed another challenge: The magnetic rigidities of the particles are so close because of the same mass-To-charge-number ratio A/Z = 2 for 16O, 12C and 4He. Hence, radical changes of the R3B setup were necessary. All detectors had slits to allow the passage of the unreacted 16O ions, while 4He and 12C would hit the detectors' active areas depending on the scattering angle and their relative energies. We developed and built detectors based on organic scintillators to track and identify the reaction products with sufficient precision.
|
|
| 11. |
- Gyürky, Gy., et al.
(författare)
-
Resonance strengths in the 14N( p,γ)15O astrophysical key reaction measured with activation
- 2019
-
Ingår i: Physical Review C. - : American Physical Society. - 2469-9985 .- 2469-9993. ; 100:1
-
Tidskriftsartikel (refereegranskat)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.
|
|
| 12. |
- Imbriani, G., et al.
(författare)
-
S-factor of 14N(p,γ)15O at astrophysical energies
- 2005
-
Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 25:3, s. 455-466
-
Tidskriftsartikel (refereegranskat)abstract
- The astrophysical S(E) factor of 14N(p,γ)15O has been measured for effective center-of-mass energies between E eff = 119 and 367 keV at the LUNA facility using TiN solid targets and Ge detectors. The data are in good agreement with previous and recent work at overlapping energies. R-matrix analysis reveals that due to the complex level structure of 15O the extrapolated S(0) value is model dependent and calls for additional experimental efforts to reduce the present uncertainty in S(0) to a level of a few percent as required by astrophysical calculations. © Società Italiana di Fisica / Springer-Verlag 2005.
|
|
| 13. |
- Imbriani, G., et al.
(författare)
-
The bottleneck of CNO burning and the age of Globular Clusters
- 2004
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 420:2, s. 625-629
-
Tidskriftsartikel (refereegranskat)abstract
- The transition between the Main Sequence and the Red Giant Branch in low mass stars is powered by the onset of CNO burning, whose bottleneck is 14N(p, γ) 15O. The LUNA collaboration has recently improved the low energy measurements of the cross section of this key reaction. We analyse the impact of the revised reaction rate on the estimate of the Globular Cluster ages, as derived from the turnoff luminosity. We found that the age of the oldest Globular Clusters should be increased by about 0.7-1 Gyr with respect to the current estimates.
|
|
| 14. |
- Marta, M., et al.
(författare)
-
Precision study of ground state capture in the 14N(p,γ)15O reaction
- 2008
-
Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 78:2
-
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.
|
|
| 15. |
- Marta, M., et al.
(författare)
-
The N14(p,γ)O15 reaction studied with a composite germanium detector
- 2011
-
Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 83:4
-
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.
|
|
| 16. |
- Trautvetter, H P, et al.
(författare)
-
Ground state capture in 14N(p,γ)15O studied above the 259 keV resonance at LUNA
- 2008
-
Ingår i: Journal of Physics G. - : IOP Publishing. - 0954-3899 .- 1361-6471. ; 35:1
-
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.
|
|
