14 Nov 2013... life cycles of stars. 11/14/2013. International Peer Review - TRIUMF. 8 nova. X-
ray burst. Image credit: Scientific American/Malcolm Godwin ...
Canada’s national laboratory for particle and nuclear physics Laboratoire national canadien pour la recherche en physique nucléaire et en physique des particules
Nuclear Astrophysics at ISAC: neutron-deficient side of stability: direct and indirect measurements
Chris Ruiz | Research Scientist | TRIUMF For the TRIUMF Nuclear Astrophysics Group
Accelerating Science for Canada Un accélérateur de la démarche scientifique canadienne Owned and operated as a joint venture by a consortium of Canadian universities via a contribution through the National Research Council Canada Propriété d’un consortium d’universités canadiennes, géré en co-entreprise à partir d’une contribution administrée par le Conseil national de recherches Canada
The origin of the chemical elements, and the behavior of stellar explosions
Core collapse supernova
Type I X-ray burst Main sequence star, giant branch stars
Classical nova
Image credits: David A Hardy, NASA, ESO/L. Caçada
11/14/2013
• What are the origins of the various groups of isotopes in the nuclear landscape? • What are the roles of nuclear reactions in stellar evolution and the energetics of stellar explosions? • Can we use radioactivity as a diagnostic probe of stellar explosions?
International Peer Review - TRIUMF
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The origin of the chemical elements, and the behavior of stellar explosions
Core collapse supernova
Type I X-ray burst Main sequence star, giant branch stars
Classical nova
Hydrostatic H, He, C, O, Ne, & Si burning in massive stars
Image credits: David A Hardy, NASA, ESO/L. Caçada
11/14/2013
• What are the origins of the various groups of isotopes in the nuclear landscape? • What are the roles of nuclear reactions in stellar evolution and the energetics of stellar explosions? • Can we use radioactivity as a diagnostic probe of stellar explosions?
International Peer Review - TRIUMF
3
The origin of the chemical elements, and the behavior of stellar explosions
rp-process (hot hydrogen fusion in equilibrium with photodissociation)
Core collapse supernova
Type I X-ray burst Main sequence star, giant branch stars
Classical nova
Hydrostatic H, He, C, O, Ne, & Si burning in massive stars
Image credits: David A Hardy, NASA, ESO/L. Caçada
11/14/2013
• What are the origins of the various groups of isotopes in the nuclear landscape? • What are the roles of nuclear reactions in stellar evolution and the energetics of stellar explosions? • Can we use radioactivity as a diagnostic probe of stellar explosions?
International Peer Review - TRIUMF
4
The origin of the chemical elements, and the behavior of stellar explosions
s-process (“cold”, slow neutron fusion)
rp-process (hot hydrogen fusion in equilibrium with photodissociation)
Core collapse supernova
Type I X-ray burst Main sequence star, giant branch stars
Classical nova
Hydrostatic H, He, C, O, Ne, & Si burning in massive stars
Image credits: David A Hardy, NASA, ESO/L. Caçada
11/14/2013
• What are the origins of the various groups of isotopes in the nuclear landscape? • What are the roles of nuclear reactions in stellar evolution and the energetics of stellar explosions? • Can we use radioactivity as a diagnostic probe of stellar explosions?
International Peer Review - TRIUMF
5
The origin of the chemical elements, and the behavior of stellar explosions γ-process (photodissociation of r- & s- isotopes) s-process (“cold”, slow neutron fusion)
rp-process (hot hydrogen fusion in equilibrium with photodissociation)
Core collapse supernova
Type I X-ray burst Main sequence star, giant branch stars
Classical nova
Hydrostatic H, He, C, O, Ne, & Si burning in massive stars
Image credits: David A Hardy, NASA, ESO/L. Caçada
11/14/2013
• What are the origins of the various groups of isotopes in the nuclear landscape? • What are the roles of nuclear reactions in stellar evolution and the energetics of stellar explosions? • Can we use radioactivity as a diagnostic probe of stellar explosions?
International Peer Review - TRIUMF
6
The origin of the chemical elements, and the behavior of stellar explosions γ-process (photodissociation of r- & s- isotopes) s-process (“cold”, slow neutron fusion)
rp-process (hot hydrogen fusion in equilibrium with photodissociation)
Core collapse supernova
Type I X-ray burst Main sequence star, giant branch stars
r-process (hot, fast neutron fusion) Classical nova
Hydrostatic H, He, C, O, Ne, & Si burning in massive stars
Image credits: David A Hardy, NASA, ESO/L. Caçada
11/14/2013
• What are the origins of the various groups of isotopes in the nuclear landscape? • What are the roles of nuclear reactions in stellar evolution and the energetics of stellar explosions? • Can we use radioactivity as a diagnostic probe of stellar explosions?
International Peer Review - TRIUMF
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Research throughout the life cycles of stars
nova X-ray burst
Image credit: Scientific American/Malcolm Godwin
11/14/2013
International Peer Review - TRIUMF
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Research throughout the life cycles of stars
nova X-ray burst
Image credit: Scientific American/Malcolm Godwin
11/14/2013
International Peer Review - TRIUMF
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Research throughout the life cycles of stars Astrophysical reactions studied at ISAC (DRAGON, TUDA, DSL) 21Na(p,γ)22Mg, 23Mg(p,γ)24Al 17O(p,γ)18F, 33S(p,γ)34Cl, 26gAl(p,γ)27Si, 18F(p,γ)19Ne, 18F(p,α)15O 40Ca(α,γ)44Ti 17O(α,γ)21Ne
nova
X-ray burst
26mAl(p,γ)27Si
18Ne(α,p)21Na
23Na(α,p)26Mg
58Ni(p,γ)59Cr 16O(α,γ)20Ne 12C(α,γ)16O
3He(α,γ)7Be 14N(p,γ)15O
Image credit: Scientific American/Malcolm Godwin
11/14/2013
International Peer Review - TRIUMF
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Research throughout the life cycles of stars Astrophysical reactions studied at ISAC (DRAGON, TUDA, DSL) 21Na(p,γ)22Mg, 23Mg(p,γ)24Al 17O(p,γ)18F, 33S(p,γ)34Cl, 26gAl(p,γ)27Si, 18F(p,γ)19Ne, 18F(p,α)15O 40Ca(α,γ)44Ti 17O(α,γ)21Ne
nova
X-ray burst
26mAl(p,γ)27Si
18Ne(α,p)21Na
23Na(α,p)26Mg
58Ni(p,γ)59Cr 16O(α,γ)20Ne 12C(α,γ)16O
3He(α,γ)7Be 14N(p,γ)15O
Nuclear Astrophysics is a collaboration between stellar modelers, astronomers, and nuclear physicists Image credit: Scientific American/Malcolm Godwin
11/14/2013
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The state of stellar models NuGrid models of classical nova outbursts
Image credit: David A Hardy
MESA Models of Classical Nova Outbursts: The Multicycle Evolution and Effects of Convective Boundary Mixing, P. A. Denissenkov et al., Astrophys. J. 762 (2013) 10 pp. MESA and NuGrid Simulations of Classical Nova Outbursts: ONe Novae and Nucleosynthesis, P. A. Denissenkov et al., in preparation
• • •
mesa.sourceforge.net MESA is state-of-the-art stellar evolution code collaboration nugridstars.org www.jinaweb.org NuGrid nucleosynthesis tools astro.triumf.ca Joint-funded TRIUMF / U.Vic / JINA (USA) work on nova models
• 11/14/2013
! now available for experimenters to evaluate impact of reaction rate measurements/ uncertainties, and to identify new experimental directions for novae nuclear physics International Peer Review - TRIUMF
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Connection between nuclear physics and astronomy • Experiments intimately linked to observations via models: Galactic 26Al: Massive stars, novae, AGB
Cas A
Image credit: NASA/JPL-Caltech
Image credit: R. Diehl
• • • INTEGRAL (& COMPTEL), NuStar etc
•
44Ti
from core-collapse supernovae (e.g. Cas A, SN 1987a) galaxy-wide, contributions from Type II SN, Asymptotic Giant Branch stars, O-Ne novae 22Na from O-Ne novae, 511-keV flux from CO and O-Ne novae Isotopic ratios from meteoric grains of pre-solar origin 26Al
Image credit: ESA
11/14/2013
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Measurement requirements
AZUREOut_aa=1_TOTAL_CAPTURE.extrap
cross section (barn)
10-4 10-5 10-6 10-7 10-8
11C(p,γ)12N
-9
calculation
10
10-10
AZUREOut_aa=1_TOTAL_CAPTURE.extrap -11
S-Factor (MeV barn)
10 10-1 0.6
0.8
1
1.2
1.4
1.6
1.8
18F(p,α)15O
S-factor:
S(E) = σ (E)Ee 2 πη 2
Ec.m. (MeV) -2
10
Aids extrapolation to lower energy
10-3
10-4
10-5
0.6
0.8
1
1.2
1.4
1.6
Ec.m. (MeV)
1.8
2
C. Beer et al. Phys. Rev. C 83 (2011) 042801
•
Cross sections can be extremely small (picobarn-microbarn for radiative capture, microbarnmillibarn for charged particle exit channel reactions) • Extrapolation into stellar energy region required for lower stellar temperature scenarios ! Most intense Radioactive Ion Beams + Long beam-time periods (e.g. radiative capture measurement might take 6 weeks at 1 x 108 pps beam intensity) Currently constrained by high beam-time subscription ! ARIEL will increase beam development and beam-time availability 11/14/2013
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Direct measurements: the DRAGON facility
Poster: J. Fallis
DRAGON: Direct measurement of proton- or α- radiative capture e.g. 21Na(p,γ)22Mg, 26g,mAl(p,γ)27Si, 23Mg(p,γ)24Al, 18F(p,γ)19Ne, 12C(α,γ)16O, 3He(α,γ)7Be, … 11/14/2013
International Peer Review - TRIUMF
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Direct measurements: the DRAGON facility
Poster: J. Fallis
DRAGON: Direct measurement of proton- or α- radiative capture e.g. 21Na(p,γ)22Mg, 26g,mAl(p,γ)27Si, 23Mg(p,γ)24Al, 18F(p,γ)19Ne, 12C(α,γ)16O, 3He(α,γ)7Be, … 11/14/2013
• •
Beam suppression usually in range 108 – 1013 Recently demonstrated highest ever beam suppression for a recoil separator > 1014 S.K.L. Sjue et al. NIM A 700, 179 (2013) International Peer Review - TRIUMF
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•
Resonance strengths as small as ~10 µeV
•
Measure in presence of strong isobaric contaminant backgrounds (1000:1)
•
Competitive stable beam measurements ! 1 µA level using offline ECR
•
High mass capture measurements for the p-process e.g. 76Se(α,γ)80Kr
24Mg(p,γ)25Al,
ER=214 keV, ωγ=13 meV
27Al(p,γ)28Si,
ER=196 keV, ωγ=14 µeV
C. Vockenhuber et al., NIMA 603, 372-378 (2009) 11/14/2013
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•
Resonance strengths as small as ~10 µeV
•
Measure in presence of strong isobaric contaminant backgrounds (1000:1)
•
Competitive stable beam measurements ! 1 µA level using offline ECR
•
High mass capture measurements for the p-process e.g. 76Se(α,γ)80Kr
23Na+23Mg
L. Erikson et al., Phys. Rev. C 81 (2010) 045808 Study of 23Mg(p,γ)24Al with 23Na(p,γ)24Mg background 23Na:23Mg=1000:1
24Mg
24Al
11/14/2013
International Peer Review - TRIUMF
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•
Resonance strengths as small as ~10 µeV
•
Measure in presence of strong isobaric contaminant backgrounds (1000:1)
•
Competitive stable beam measurements ! 1 µA level using offline ECR
•
High mass capture measurements for the p-process e.g. 76Se(α,γ)80Kr Avge. beam intensity = 1 x 1012 s-1
Avge. beam intensity = 1.6 x 1010 s-1
Singles events γ-coincident events
Recoil 20Ne
16O(α,γ)20Ne:
11/14/2013
Leaky
34Cl
16O
U. Hager et al., Phys. Rev. C 86 (2012) 055802
recoils
33S(p,γ)34Cl:
International Peer Review - TRIUMF
J. Fallis et al., Phys. Rev. C 88 (2013) 045801 19
•
Resonance strengths as small as ~10 µeV
•
Measure in presence of strong isobaric contaminant backgrounds (1000:1)
•
Competitive stable beam measurements ! 1 µA level using offline ECR
•
High mass capture measurements for the p-process e.g. 76Se(α,γ)80Kr 58Ni(p,γ)59Cr
demonstrator experiment
59Cr
recoils
A. Simon et al., Eur. Phys. J A 49 (2013) 11/14/2013
International Peer Review - TRIUMF
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•
Resonance strengths as small as ~10 µeV
•
Measure in presence of strong isobaric contaminant backgrounds (1000:1)
•
Competitive stable beam measurements ! 1 µA level using offline ECR
•
High mass capture measurements for the p-process e.g. 76Se(α,γ)80Kr 58Ni(p,γ)59Cr
demonstrator experiment
59Cr
recoils
A. Simon et al., Eur. Phys. J A 49 (2013) 11/14/2013
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DRAGON: studied reactions RIB/ Stable
Reaction
Motivation
Average intensity (s-1)
Purity Effectively 100%
"
21Na(p,γ)22Mg
22Na
survival in O-Ne novae
5 x 109
"
12C(α,γ)16O
C/O ratio in stellar helium burning
3 x 1011
"
26gAl(p,γ)27Si
Nova contribution to galactic 26gAl
2.5 x 109
"
12C(12C,γ)24Mg
Nuclear cluster models
3 x 1011
"
40Ca(α,γ)44Ti
44Ti
3 x 1011
"
12C(16O,γ)28Si
Nuclear cluster models
3 x 1011
"
23Mg(p,γ)24Al
26gAl/22Na
5 x 107
"
17O(α,γ)21Ne
Neutron-poison in massive stars
1 x 1012
"
18F(p,γ)19Ne
Earliest nova γ-ray signals (511 keV)
2 x 106
"
33S(p,γ)34Cl
S isotopic ratios in presolar grains
1 x 1010
"
16O(α,γ)20Ne
Stellar helium burning
1 x 1012
"
17O(p,γ)18F
Nova explosive hydrogen burning
1 x 1012
"
3He(α,γ)7Be
Solar neutrino spectrum
5 x 1011
"
58Ni(p,γ)59Cu
High mass tests ! p-process, XRB
6 x 109
26g CCSN contribution toReview galactic International Peer - TRIUMFAl
2 x 105
26mAl(p,γ)27Si "11/14/2013
production in CCSN
from O-Ne novae
(desired:contaminant)
30,000:1
10,000:1 – 200:1
1:20 – 1:1000
100:1
1:10,000
22
Notable results: 23Mg(p,γ)24Al • •
23Mg(p,γ)24Al
reaction affects ejected 22Na and 26Al abundances (observables) in O-Ne nova models Reaction previously unmeasured
23Mg(p,γ)24Al
reaction rate measured experimentally for first time, to required level of uncertainty
11/14/2013
International Peer Review - TRIUMF
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Notable results: 18F(p,γ)19Ne •
18F(p,γ)19Ne
reaction partially determines 511-keV line emission from O-Ne novae (strongest and earliest signal)
J. José & M. Hernanz, Astrophys. J 494 (1998)
18F(p,γ)19Ne
resonance measured experimentally for first time
11/14/2013
International Peer Review - TRIUMF
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TUDA: TRIUMF-UK Detector Array
7Li(8Li,7Li)8Li
D. Howell et al., Phys. Rev. C 88, 025804 (2013) 18F(p,α)15O
• Direct cross-section measurements of charged particle reactions e.g. 18F(p,α)15O, 21Na(p,α)18Ne, 18Ne(α,p)21Na • Elastic Scattering e.g. 20,21Na(p,p), 18F(p,p), 7Li(8Li,7Li)8Li • Indirect e.g. transfer! ANC, spectroscopy C. Beer et al. Phys. Rev. C 83 (2011) 042801 11/14/2013
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DSL: Doppler Shift Lifetimes Doppler Shift Lifetimes Facility: Excited state lifetime measurements in fs-ps range (above particle threshold, in order to determine e.g. radiative capture strengths) E.g. Recent studies on 19Ne, 15O, 23Mg lifetimes for x-ray burst ignition, ages of oldest stars, nova nucleosynthesis.
11/14/2013
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DSL: Doppler Shift Lifetimes 3He(20Ne,α)19Ne:
S. Mythili et al., Phys. Rev. C 77 (2008) 035803 3He(16O,α)15O:
N. Galinski et al., in
preparation 3He(24Mg,α)23Mg:
Doppler Shift Lifetimes Facility: Excited state lifetime measurements in fs-ps range (above particle threshold, in order to determine e.g. radiative capture strengths) E.g. Recent studies on 19Ne, 15O, 23Mg lifetimes for x-ray burst ignition, ages of oldest stars, nova nucleosynthesis.
O. Kirsebom et al., under
analysis
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SHARC(+TIGRESS): beginning astro. program SHARC + TIGRESS Combination allows high-precision particle-gamma coincidence detection for nucleon transfer reactions (d,p), (6Li,d), (6Li,α), (3He,d), etc. e.g. 6Li(20Na,α)22Mg ! Populate states & detect p-γ coincidences: determine state properties relevant to 18Ne(α,p)21Na reaction for Type I X-ray bursters Also inelastic scattering, e.g. 23Mg(p,p’)23Mg for 23Mg(p,γ)24Al reaction rate (complementary to DRAGON)
11/14/2013
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IRIS IRIS: Solid hydrogen target scattering facility for (p,d), (p,t), (d,p), (d,n), … Can extract spectroscopic factors ! indirect determination of stellar reaction rates
Commissioned 2013, now fully operational ! solid deuterium target and 11Li(d,p)12Li ! Led in Canada by St. Mary’s University (R. Kanungo) with local participation plus major Japanese investment (~$200k) 11/14/2013
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EMMA: ElectroMagnetic Mass Analyzer
EMMA (Electromagnetic Mass Analyser) Recoil mass spectrometer capable of M/ΔM>300 (separate recoils from beam) ! Transfer reactions at large A, e.g. 132Sn(d,p)133Sn ! Fusion evaporation reactions ! Could be powerfully combined with TIGRESS/SHARC and neutron array for particle/gamma tagging ! Currently undergoing installation at ISACII 11/14/2013
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Collaborators: Canada, USA, Europe, Asia, ... Astrophysics Experiments Colorado School of Mines, USA
Stellar Modelling/ Nucleosynthesis University of Victoria, BC
Astrophysics Experiments University of Edinburgh, UK
Astrophysics Experiments University of York, UK
Astrophysics Experiments McMaster University, ON
Local Experimental Group Astrophysics Experiments Michigan State University, USA
Astrophysics Experiments China Institute for Atomic Energy, China
Astrophysics Experiments University of Surrey (New!)
Local Theory Group + external collaborators Stellar Modelling/ Nucleosynthesis + Experiments Polytechnic University of Catalunia, Spain
Astrophysics Experiments Spanish Groups (Madrid, Valencia)
Astrophysics Experiments/ theory Joint Institute for Nuclear Astrophysics (Notre Dame University)
Stellar Modelling,
Canada: TRIUMF, Vancouver, British Columbia;Simon Fraser University, Burnaby, British Columbia;University of Toronto, Toronto, Ontario;University of Northern British Columbia, Nucleosynthesis Prince George, British Columbia;University of Victoria, Victoria, British Columbia;University of Alberta, Edmonton, Alberta;McMaster University, Hamilton, Ontario;University of Guelph, Guelph, Ontario;University of PEI, Charlottetown, PrinceUniversity Edward Island,of Canada Basel, Switzerland International: Wright Nuclear Structure Laboratory, Yale University, New Haven, Conneticut, USA;Colorado School of Mines, Golden, Colorado, USA;University of Edinburgh, Edinburgh, Scotland;University of York, York, England;Universitat Politécnica de Catalunya, Barcelona, Spain;Institut d Estudis Espacials de Catalunya, Barcelona, Spain;National Astrophysics Experiments University of Ireland, Co. Kildare, Eire;Westfälische Willhelms-Universität Münster, Münster, Germany;Katholieke Universiteit Leuven, Leuven, Belgium;Clemson University, Weizmann Institute Environmental Research Accelerator (VERA), Vienna, Austria;Racah Institute of Physics, Hebrew University, Jerusalem, Israel;Argonne Clemson, South Carolina, USA;Vienna National Laboratory, Argonne, Illinois, USA;IPHC, Université Louis Pasteur, Strasbourg, France;University of Liverpool, Liverpool, England;Ohio University, Ohio, USA;University of Konstanz, Konstanz, Germany;Ruhr-Universität, Bochum, Germany;Saha Institute of Nuclear Physics, Calcutta, India;China Institute for Atomic Energy, Beijing, China;CNS, University of Tokyo, Tokyo, Japan;Dipartimento di Scienze Fisiche dell Université di Napoli Federico II, Napoli, Italy
+ many other short-term collaborators in experiments, theory, modeling
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Take away points • The neutron-deficient nuclear astrophysics program at TRIUMF is both relevant and world-leading • Intimate connection to astronomy and latest stellar modeling through local and international collaborations
• Facilities at TRIUMF are cutting edge • DRAGON unique in the world • Coupled with RIBs, puts TRIUMF far ahead of competition
• ARIEL is essential to expand the program Meet the needs of the most difficult direct measurements by: • Fresh ISOL beam development (beamline 4N, additional proton spallation capability) • Increased beam-time availability (multi-user capability, longer beam-times) 11/14/2013
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Canada’s national laboratory for particle and nuclear physics Laboratoire national canadien pour la recherche en physique nucléaire et en physique des particules
Thank you! Merci Supplementary slides available !
Owned and operated as a joint venture by a consortium of Canadian universities via a contribution through the National Research Council Canada Propriété d’un consortium d’universités canadiennes, géré en co-entreprise à partir d’une contribution administrée par le Conseil national de recherches Canada
TRIUMF: Alberta | British Columbia | Calgary | Carleton | Guelph | Manitoba | McGill | McMaster | Montréal | Northern British Columbia | Queen’s | Regina | Saint Mary’s | Simon Fraser | Toronto | Victoria | Winnipeg | York
Selected publications by Facility/Group DRAGON + direct radiative capture measurements J. Fallis I et al., Physical Review C 88, 045801 (2013). G. Christian et al., Physical Review C 88, 038801 (2013). C. Akers et al., Physical Review Letters 110, 262502 (2013). A. Simon et al., Eur. Phys. J. A 49, #60, (2013). S.K.L. Sjue et al., Nucl. Instr. Meth. Phys. Res. 700, 179 (2013). U. Hager et al., Physical Review C 86, 055802 (2012). U. Hager et al., Physical Review C 85, 035803 (2012). U. Hager et al., Physical Review C 84, 022801(R) (2011). A. Sallaska et al., Physical Review C 83, 034611 (2011). L. Erikson et al., Physical Review C 81, 045808 (2010). A. Sallaska et al., Physical Review Letters 105, 152501 (2009). C. Vockenhuber et al., J. Phys. G: Nucl. Part. Phys. 35, 014034 (2008).
TUDA direct measurements C. Beer et al., Physical Review C 83, 042801 (2011). A. St. J. Murphy et al., Phys. Rev. C 79, 058801 (2009). TUDA/DSL indirect measurements D. Howell et al., Phys. Rev. C 88, 025804 (2013). N. Galinski et al., in preparation (2013). P. Salter et al., Physical Review Letters 108, 242701 (2012). S. Mythili et al., Phys. Rev. C 77, 035803 (2008).
Stellar modeling/Nucleosynthesis/Theory P. Denissenkov et al., Astrophysical Journal, 762, 8 (2013). S. Bacca et al., Astrophysical Journal 758, 34 (2012). P. Navrátil and S. Quaglioni, Physical Review Letters 108, 042503 (2012). O. Kirsebom and B. Davids, Physical Review C 84, 058801 (2011). P. Navrátil, R. Roth, and S. Quaglioni, Physics Letters B 704, 379 (2011). V. Cirigliano, S. Reddy, and R. Sharma, Physical Review C 84, 045809 (2011). B. Davids, R. Cyburt, J. José, and S. Mythili, Astrophysical Journal 735, 40 (2011). K. Hebeler et al., Physical Review Letters 105, 161102 (2010). L. Buchmann et al., Phys. Rev. C 80, 045803 (2009).
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HQP successes (DRAGON and Astro Program): Postdoctoral Trainees C. Vockenhuber, Head of AMS Laboratory at ETH Zurich M. Trinzcek, Head of Proton Irradiation Facility, TRIUMF U. Hager, Assistant Professor at Colorado School of Mines G. Ruprecht, Researcher at IFK Berlin, and founding member of the Dual Fluid Reactor project R. Kanungo, Associate Professor, St. Mary's University S. Sjue, Research Scientist, Los Alamos National Laboratory Graduate Trainees A. Parikh, Lecturer (Prof. Lector) at Polytechnic University of Catalunia, international expert on Novae and type I X-ray burst modeling L. Erikson, Research Scientist at Pacific Northwest Laboratories, WA D. Howell, Instructor, University of the Fraser Valley
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Experiments with approved beam time for coming 2 years red=RIB • S870 - Breakout from the Hot CNO Cycle via the 18Ne(α,p)21Na reaction (TEST) • S989 – Measurement of the 26mAl(p,γ) 27Si reaction for One novae and supernovae using an isomeric radioactive P. Navrátil et al. / Physics Letters B 704 (2011) 379–383 381 beam suggested 0+ resonance at 1.9 MeV is quite close to the calculated 0+ energy of the present work. While our calculated D-wave phase • S1025 - 7Be+p: Elastic Scattering shifts show a slow monotonic increase, the S-wave phase shifts 27Si reaction rise at low energies and then decrease, as seen in Fig. 3(a). This is • S1171 - An 26Al target to measure low-energy resonances in the 26gAl(p,γ) a similar behavior as that found in microscopic three-cluster model 76 80 calculations of Ref. [15], while in potential model calculations the • S1318 - A direct measurement of the Se(α,γ) Kr reaction S-wave phase shift monotonically decreases with energy [15]. Our extracted S-wave scattering lengths are −15.3 fm and −5.2 fm for • S1363 - Measuring the astrophysical 20Ne(p,γ)21Na and 21Ne(p,γ)22Na rates at DRAGON the s = 2 and s = 1 channels, respectively. The experimental value for s = 2 scattering length is −7(3) fm [35]. The s = 1 scattering 11 12 • S1398 - Direct measurement of astrophysical C(p,γ) N reaction atlength DRAGON has a very large uncertainty. We also note that our calculated scattering lengths decrease in absolute value with increasing 18 19 15 19 15 15 • S1425 - The F(p,γ) Ne reaction via O(α,γ) Ne and O(α,α) O values of the SRG parameter Λ: For Λ = 2.02 fm− we found an s = 2 S-wave scattering length .2 fm [21]. Negative scat38K(p,γ) 39of −10reaction • S1442 - The end-point of novae nucleosynthesis: Direct measurement thewere teringof lengths also found inCa the cluster model ofin Ref.inverse [15], although there the s = 2 scattering length was fitted to the experikinematics mental value mentioned above (−7 fm). The impact of the S-wave 1
Fig. 3. (Color online.) Selected S- (a) D- (a), and P -wave (b) diagonal phase shifts of
DRAGON/Colorado School of Mines 7Be p- Be elastic scattering, inelastic Be( p , p ) Be(1/2 ) cross section (c ) and elastic Be( p , p ) Be differential cross section at et Θ = 148 (Phys. d). Calculations as described P. Navrátil al., in Fig. 2. +p scattering chamber + windowless gas Lett. B 704, 379 (2011) target HIGH PRIORITY 7
7
11/14/2013
7
7
′ 7
c .m.
−
◦
of relative motion and the channel spins s = 1 and s = 2 we obtained C 11 = 0.294 fm−1/2 and C 12 = 0.650 fm−1/2 , respectively. Next, we solve the same NCSM/RGM equations (3) with scattering-state boundary conditions for a chosen range of energies and obtain scattering wave functions and the scattering matrix. The resulting phase shifts and cross sections are displayed in Fig. 3. All energies are in the center of mass (c.m.). We find several P -wave resonances in the considered energy range. The first 1+ reso-
scattering length on the S-factor was also discussed in Refs. [12] and [36]. With the resulting bound- and scattering-state wave functions that are properly orthonormalized and antisymmetrized (1), we calculate the 7 Be( p , γ )8 B radiative capture using a one-body E1 transition operator. We use the one-body E1 operator defined in Eq. (3) of Ref. [37] that includes the leading effects of the mesonexchange currents through the Siegert’s theorem. Here we note that any renormalization of the E1 operator brought about by the SRG procedure should be negligible as the E1 is a long-range operator while the SRG transformation is short range, when performed within the interval of Λ values used in the present calculations. The resulting S 17 factor is compared to several experimental data sets in panel (a) of Fig. 4. In the data, one can see also the contribution from the 1+ resonance due to the M1 capture that does not contribute to a theoretical calculation outside of the resonance and is negligible at astrophysical energies [2]. While the M1 operator poses more uncertainties than the Siegert’s E1 operator (owing to the possible need of explicit two-body currents), its treatment within the NCSM/RGM formalism requires the evaluation of contributions from both the relative-motion part and the core (7 Be) part of the wave function and is only slightly more complicated compared to the E1 case. We plan to calculate its contribution in the 18calculated S-factor 19 future. Our is somewhat lower than15 the recent Junghans data [5] but the shape reproduces closely the trend of 15 15 the GSI data [8], which were extracted from Coulomb breakup. The shape is also quite similar to that obtained within the microscopic three-cluster model [15] (see the dashed line in Fig. 4(a)) used, after scaling to the data, in the most recent S 17 evaluation [2]. The contributions from the initial 1− , 2− and 3− partial waves are shown in panel (b) of Fig. 4. Our calculated S 17 (0) ≈ 19.4 eV b is on the lower side, but consistent with the latest evaluation 20.8 ± 0.7(expt) ± 1.4(theory) eV b [2]. We studied the convergence of the 7 Be NCSM calculations in Fig. 1. To verify the behavior of our S-factor with respect to HO ba-
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F(p,γ) Ne reaction via O(α,γ)19Ne and O(α,α) O HIGH PRIORITY 36
