Presentation is loading. Please wait.

Presentation is loading. Please wait.

Searching for the Low-Energy Resonances in the 12 C( 12 C,n) 23 Mg Reaction Cross Section Relevant for S-Process Nucleosynthesis Brian Bucher University.

Published byOphelia Hubbard Modified over 9 years ago

Similar presentations

Presentation on theme: "Searching for the Low-Energy Resonances in the 12 C( 12 C,n) 23 Mg Reaction Cross Section Relevant for S-Process Nucleosynthesis Brian Bucher University."— Presentation transcript:

1 Searching for the Low-Energy Resonances in the 12 C( 12 C,n) 23 Mg Reaction Cross Section Relevant for S-Process Nucleosynthesis Brian Bucher University of Notre Dame

2 Outline 12 C( 12 C,n) 23 Mg in the weak s-process & rate uncertainty Measurement at ND via 23 Mg decays Prediction based on mirror system 12 C( 12 C,p) 23 Na Measurement at ND via n-detection Results & astrophysical implications

3 Effect on Carbon-Shell Yields Pignatari, Priv. Comm. 12 C( 12 C,n) rate varied by factors 2, 5, 10 T 9 =1.1 Results are model- dependent

4 Becker et al. 1981 Spillane et al. 2007 Typical C-shell burning 1977 1969 Uncertainty in Reaction Rate Resonances form important contribution to excitation function Resonance structure continues to lowest energies Current rate cannot account for resonances 12 C( 12 C,n) 23 Mg 12 C+ 12 C 12 C+ 12 C→  + 20 Ne →p+ 23 Na →n+ 23 Mg ? Q  =+4.6 MeV Q p =+2.2 MeV Q n =-2.6 MeV Low E resonances measured in total fusion x-section

5 1 st Measurement of 12 C( 12 C,n) 23 Mg at Notre Dame Online  -rays for p &  channel Our Setup Detect  + from 23 Mg decay (t 1/2 =11s)

6 Experimental Results Measured finer step size over large energy range Consistent with others Note consistent resonance energies PRELIMINARY Difficult to measure lower Low cross-section Increasing background due to reactions with H/D

7 Becker et al. Z. Phys. A303, 305-312 (1981) n-channel difficult to measure at low E Can p-channel(s) provide useful information for n-channel 24 Mg* n2 n1 n0 12 C p2 p1 p0 Mirror Nuclei Low-Energy Extrapolation

8 n-channel prediction using Becker et al. p-channel measurements 1.Gross structure reproduced 2.Energy & strength mismatch 3.Low-E resonance predicted Perform measurement at ND to check these results…..

9 The backward angle θ Lab : 113.5° - 163.5° θ cm : 122.5° - 166.3° Solid angle calibrated by mixed alpha source 2.59% 3 MeV<E cm <5.7 MeV 0.5 p  A 12 C beam from FN tandem target YY1 detector Focus on: 12 C( 12 C, p) 23 Na More details are available in Thursday, May 31, Session 27: Nuclear Astrophysics-3, Room 3: PECAN 5:50-6:10 pm Experimental Investigations Of Stellar 12C+12C Fusion Toward Extremely Low Energies by Direct And Indirect Methods Xiao Fang, University of Notre Dame, Notre Dame, Indiana, USA

10 Extrapolation Using New Measurement PRELIMINARY Assumed isotropic angular distribution 1.Better overall agreement 2.Low-E resonance not as strong

11 2 nd Measurement: Direct detection of neutrons using 3 He array Beam Target LN 2 reservoir Turbo Pump 3 He proportional counter Polyethylene moderator Central bore for beam tube

12 1.Improved detection efficiency (>40%) 2.Low-E measurements hindered by D( 12 C,n) HOPG graphite much cleaner! Highly Ordered Pyrolytic Graphite (renewable surface) Thick Target Neutron Yield Curves Use 13 C beam to measure background component 13 C( 12 C,n) Flat component presumably D( 12 C,n) (target or beam line) PRELIMINARY

13 Results Good agreement with prediction! 3.4 MeV resonance confirmed as predicted (p0 & p1) Detector efficiency from Geant4 PRELIMINARY

14 Astrophysical Rate Sensitivity to Remaining Excitation Function Resonance below 3.0 MeV from Zickefoose PhD thesis, UConn 2010 Measured p0+p1 from HOPG Assumed isotropic distribution Here we assume full strength to p0 channel n0 prediction (n1 closed) Typical shell- carbon burning Predict a maximum of 2x enhancement for weak s-process due to potential resonances at lower energies

15 Summary 12 C( 12 C,n) can be an important component to the weak s-process Reaction measured via 2 different methods at ND 1 st measurement at energies of astrophysical relevance Mirror system-based prediction provides good agreement Uncertainty in rate is reduced with new measurements

16 Thank You! Collaborators: X. Fang, J. Browne, A. Alongi, C. Cahillane, E. Dahlstrom, A. Moncion, W. Tan, M. Notani, X.D. Tang Nuclear Science Lab: S. Almaraz-Calderon, A. Ayangeakaa, A. Best, M. Couder, J. DeBoer, W. Lu, D. Patel, N. Paul, A. Roberts, R. Talwar, A. Kontos, M. Smith, S. Lyons, Q. Li, K. Smith, A. Long, M. Beard, M. Wiescher

Download ppt "Searching for the Low-Energy Resonances in the 12 C( 12 C,n) 23 Mg Reaction Cross Section Relevant for S-Process Nucleosynthesis Brian Bucher University."

Similar presentations

Does the 12 C+ 12 C fusion reaction ignite superbursts?

Does the 12 C+ 12 C fusion reaction ignite superbursts?
Γ spectroscopy of neutron-rich 95,96 Rb nuclei by the incomplete fusion reaction of 94 Kr on 7 Li Simone Bottoni University of Milan Mini Workshop 1°-

Γ spectroscopy of neutron-rich 95,96 Rb nuclei by the incomplete fusion reaction of 94 Kr on 7 Li Simone Bottoni University of Milan Mini Workshop 1°-
The Role of 12 C( 12 C,n) in the Astrophysical S-Process Brian Bucher University of Notre Dame.

The Role of 12 C( 12 C,n) in the Astrophysical S-Process Brian Bucher University of Notre Dame.
The 12C+12C fusion reaction: a new opportunity at ATLAS Xiaodong Tang 1 & Chenglie Jiang 2 1) Univ. of Notre Dame 2) ANL.

The 12C+12C fusion reaction: a new opportunity at ATLAS Xiaodong Tang 1 & Chenglie Jiang 2 1) Univ. of Notre Dame 2) ANL.
Low energy radioactive beams Carmen Angulo, CRC Louvain-la-Neuve, Belgium FINUPHY meetingLouvain-la-Neuve, Belgium3-4 May 2004 Recent highlights on nuclear.

Low energy radioactive beams Carmen Angulo, CRC Louvain-la-Neuve, Belgium FINUPHY meetingLouvain-la-Neuve, Belgium3-4 May 2004 Recent highlights on nuclear.
The Dynamical Deformation in Heavy Ion Collisions Junqing Li Institute of Modern Physics, CAS School of Nuclear Science and Technology, Lanzhou University.

The Dynamical Deformation in Heavy Ion Collisions Junqing Li Institute of Modern Physics, CAS School of Nuclear Science and Technology, Lanzhou University.
A Precision Measurement of the Neutral Pion Lifetime via the Primakoff Effect Jefferson Lab Experiment E99-014 PrimEx Collaboration Eric R. I. Clinton.

A Precision Measurement of the Neutral Pion Lifetime via the Primakoff Effect Jefferson Lab Experiment E PrimEx Collaboration Eric R. I. Clinton.
Astrophysical Reaction Rate for the Neutron-Generator Reaction 13 C(α,n) in Asymptotic Giant Branch Stars Eric Johnson Department of Physics Florida State.

Astrophysical Reaction Rate for the Neutron-Generator Reaction 13 C(α,n) in Asymptotic Giant Branch Stars Eric Johnson Department of Physics Florida State.
Astrophysical S(E)-factor of the 15 N(p,α) 12 C reaction at sub-Coulomb energies via the Trojan-horse method Daniel Schmidt, Liberty University Cyclotron.

Astrophysical S(E)-factor of the 15 N(p,α) 12 C reaction at sub-Coulomb energies via the Trojan-horse method Daniel Schmidt, Liberty University Cyclotron.
Reaction rates in the Laboratory Example I: 14 N(p,  ) 15 O stable target  can be measured directly: slowest reaction in the CNO cycle  Controls duration.

Reaction rates in the Laboratory Example I: 14 N(p,  ) 15 O stable target  can be measured directly: slowest reaction in the CNO cycle  Controls duration.
Status Report of Neutron Detector Simulation Development Brian Roeder Postdoc LPC Caen 20 Sept. 2007.

Status Report of Neutron Detector Simulation Development Brian Roeder Postdoc LPC Caen 20 Sept
Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft Neutron capture cross sections on light nuclei M. Heil, F. Käppeler, E. Uberseder Torino workshop,

Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft Neutron capture cross sections on light nuclei M. Heil, F. Käppeler, E. Uberseder Torino workshop,

12C(p,g)13N g III. Nuclear Reaction Rates 12C 13N Nuclear reactions

12C(p,g)13N g III. Nuclear Reaction Rates 12C 13N Nuclear reactions
Astrophysical S(E)-factor of the 15N(p,α)12C reaction at sub-Coulomb energies via the Trojan-horse method Daniel Schmidt, Liberty University Cyclotron.

Astrophysical S(E)-factor of the 15N(p,α)12C reaction at sub-Coulomb energies via the Trojan-horse method Daniel Schmidt, Liberty University Cyclotron.
Reaction rates in the Laboratory Example I: 14 N(p,  ) 15 O stable target  can be measured directly: slowest reaction in the CNO cycle  Controls duration.

Reaction rates in the Laboratory Example I: 14 N(p,  ) 15 O stable target  can be measured directly: slowest reaction in the CNO cycle  Controls duration.
Reaction rates in the Laboratory Example I: 14 N(p,  ) 15 O stable target  can be measured directly: slowest reaction in the CNO cycle  Controls duration.

Reaction rates in the Laboratory Example I: 14 N(p,  ) 15 O stable target  can be measured directly: slowest reaction in the CNO cycle  Controls duration.
Nuclear and Radiation Physics, BAU, 1 st Semester, 2006-2007 (Saed Dababneh). 1 Nuclear Reactions Categorization of Nuclear Reactions According to: bombarding.

Nuclear and Radiation Physics, BAU, 1 st Semester, (Saed Dababneh). 1 Nuclear Reactions Categorization of Nuclear Reactions According to: bombarding.
25 9. Direct reactions - for example direct capture: Direct transition from initial state |a+A> to final state B +  geometrical.

25 9. Direct reactions - for example direct capture: Direct transition from initial state |a+A> to final state B +  geometrical.
1 III. Nuclear Reaction Rates Nuclear reactions generate energy create new isotopes and elements Notation for stellar rates: p 12 C 13 N  12 C(p,  )

1 III. Nuclear Reaction Rates Nuclear reactions generate energy create new isotopes and elements Notation for stellar rates: p 12 C 13 N  12 C(p,  )

Similar presentations

Ads by Google