31 S for nuclear astrophysics α 28 Si test experiment IFINHH IC Stefanescu 12 AI Chilug 12 L Trache 1 A Spiridon 1 D Tudor 12 N M ă rginean 1 A Turturică ID: 778611
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Slide1
“Complete spectroscopy” of 31S for nuclear astrophysicsα+28Si test experiment @ IFIN-HH
I.C. Stefanescu1,2, A.I. Chilug1,2, L. Trache1, A. Spiridon1, D. Tudor1,2, N. Mărginean1, A. Turturică1, L. Stan1, D. Filipescu1, N. Florea1, C. Costache1, S. Ujeniuc1, E. Radu11 Horia Hulubei National Institute for R&D in Physics and Nuclear Engineering (IFIN-HH)2 University of Bucharest, Doctoral School of Physics, Bucharest, Romania
Slide2Astrophysical scenarioClassical novae: binary system where hydrogen-rich material accretes on a white dwarf from its low-mass main-sequence companionThermonuclear runaway ↔ proton reactions ↔ many important reactions are dominated by
resonant capture…BUT…what is the reaction rate?A(p,γ)B - the ones that count for nucl. astrophysics take place in Gamow windowResonant capture contribution to the reaction rate:Russbach School on Nuclear Astrophysics, 10 - 16 March 2019
Slide3Astrophysical scenarioLarge uncertainties and large variations in the end products of the nova outbursts30P(p,γ)31S
– the most important reaction in novae nucleosynthesis; bottleneck passing point beyond sulphur elementsCapture is dominated by resonances – excited states in 31SDifficult to study directlySolution: use different methods 28Si(α,nγ)31S Study of the spectroscopy of the 31S nucleus at Eex ~ 7 MeV (Sp=6.13 MeV)! Keep an eye on spins & paritiesRussbach School on Nuclear Astrophysics, 10 - 16 March 2019The excited states in the region of interest are not well knownROI (considering different scenarios about novae temperatures): 6.13 MeV ↔ 7 MeV
Slide4Previous work on 30P(p,γ)31S
2009@IFIN-HH2012@GammaSPHERERussbach School on Nuclear Astrophysics, 10 - 16 March 2019Only HPGe detectorsα+28Si 31S+n+γDoherty et al., “Key resonances in the 30P(p,γ)31S Gateway Reaction for theProduction of Heavy Elements in One Novae”, PRL 108
, 262502 (2012)
I. Stefanescu
, “A detection system for very low energy
β
-delayed proton decay”
, FAIRNESS 2017
β
-delayed proton decay of
31
Cl @TAMU
spectrum gated on 1249keV transition
Slide52018 ExperimentReaction: α+28Si @ E
α=22 MeV & Iα=1 pnANatural Si target; 0.57mg/cm2 deposited on 4.29mg/cm2 Ta – problems due to contaminants 29Si & 30SiReaction channel of interest: 28Si(α,nγ)31SMain goals: Populate low-spin excited states in 31S, in the region of interesthave a good discrimination in neutron detectors, between neutrons and gammasidentify good neutron – gamma coincidencesidentify γ rays in region Eex=6.13 – 7 MeV, that decay directly to ground stateExperimental set-up – 9MV Tandem Accelerator + RoSPHERE detector array: 20HPGe + 5 neutron detectors only 18
HPGe functional during experiment
2 weeks of beam
Energy calibration done with
152
Eu &
13
C(
α
,n
γ
)
16
O reaction – enriched
13
C target, 31mg/cm
2
Russbach
School on Nuclear Astrophysics, 10 - 16 March 2019
New!!!
Use
HPGe
+ neutron detectors
Slide6Experimental set-upRussbach School on Nuclear Astrophysics, 10 - 16 March 2019
Slide7Very, very preliminary resultsRussbach School on Nuclear Astrophysics, 10 - 16 March 2019
Energycounts16O, 6128 keV,s-escape, d-escape13C, 3684 & 3853 keV40K
Slide8Very, very preliminary resultsRussbach School on Nuclear Astrophysics, 10 - 16 March 2019
31S, 1249 keV31P, 1266 keVEnergycounts
Slide9Very, very preliminary resultsRussbach School on Nuclear Astrophysics, 10 - 16 March 2019
countsEnergy31S, 1249 keV31P, 1266 keV
Slide10Very, very preliminary resultsRussbach School on Nuclear Astrophysics, 10 - 16 March 2019
countsEnergy31S, 6138?! keVFuture plans: nov 2019, a new experiment – 28Si isotopic pure target
Slide11Thank you for your patience Russbach School on Nuclear Astrophysics, 10 - 16 March 2019
Slide12COST Acknowledgements www.chetec.eu
The ChETEC Action (CA16117) is supported by COST (www.cost.eu). COST (European Cooperation in Science and Technology) is a funding agency for research and innovation networks. Our Actions help connect research initiatives across Europe and enable scientists to grow their ideas by sharing them with their peers. This boosts their research, career and innovation.Funded by the Horizon 2020 Framework Programme of the European UnionSee www.chetec.eu for more details