Nuclear Structure and Reactions at NSCL and FRIB through the Lens of Astrophysics: Lecture 3 Chris Wrede HUGS @ JLab May 30 th , 2019
Nuclear Structure and Reactions at NSCL and FRIB through the Lens of
Astrophysics: Lecture 3Chris Wrede
HUGS @ JLab
May 30th, 2019
Outline
• Lecture 1: Stellar evolution & thermonuclear rates
• Lecture 2: Charged-particle reactions: direct measurements
• Lecture 3: Charged-particle reactions: indirect measurements
• Lecture 4: Slow neutron capture process: direct measurements
• Lecture 5: Rapid neutron capture process: indirect measurements
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Today
• Nova contribution to Galactic 26Al?
• b decay of 26P to probe 25Al(p,g)26Si
• Are pre-solar “nova” grains from novae?
• b decay of 31Cl to probe 30P(p,g)31S
• Conditions for CNO-cycle breakout in X-ray bursts?
• b decay of 20Mg to probe 15O(a,g)19Ne
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Radioactive 26Al across Milky Way
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Data from COMPTEL & INTEGRAL-SPI
Figure courtesy of MPE Garching / Roland Diehl
There are two solar masses of radioactive 26Al in the Milky Way. There is also 60Fe and both are produced in massive stars and supernovae. Could be nice constraint for models of massive stars and supernovae, but 26Al is also produced in novae: how much?
Classical novae
S. Starrfield et al., (1971, 1972)
J. Jose et al., Nucl. Phys A777, 550 (2006) 5C. Wrede, HUGS, May 2019
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Nova Cygni 1992 (in 1994)
NASA, ESA, HST
Nucleosynthesis in novae
J. Jose, Proceedings of Science, NIC XI 050 (2011)
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25Al(p,g)26Si reaction in novae
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The 25Al(p,g)26Si reaction can bypass 26Al production during explosive hydrogen burning because 26Si beta decays to stable 26Mg through 26Al isomer.
Measuring key 3+ 25Al(p,g)26Si resonance strength with 26P decay
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g
gg
p
p
12
7
NSCL experiment E10034
M. B. Bennett et al., Phys. Rev. Lett. 111, 232503 (2013)
One resonance dominates 25Al(p,g)26Si reaction rate. Can’t measure it directly (no 25Al RIB available). But can determine resonance strengths by measuring partial widths: p is known, just need g. Measuring their ratio is sufficient.
Production of 26P at NSCL
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• 150 MeV/u, 75 pnA 36Ar beam, 1.55 mg/cm2 Be target
• 75% pure beam of up to 100 26P ions per second at experiment
M. B. Bennett et al., Phys. Rev. Lett. 111, 232503 (2013)
Detectors
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GeDSSD
SeGA
M. B. Bennett et al., Phys. Rev. Lett. 111, 232503 (2013)
N. Larson, S. N. Liddick et al., NIMA 727, 59 (2013)
W. F. Mueller et al., NIMA 466, 492 (2001)
26P(b+g)26Si spectrum
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M. B. Bennett et al., Phys. Rev. Lett. 111, 232503 (2013)
Astrophysical Conclusions
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M. B. Bennett et al., Phys. Rev. Lett. 111, 232503 (2013)
Nucleosynthesis simulations by Jordi Jose (UPC Barcelona)
Amount of 26Al produced in novae on white dwarfs of different masses:
Conclusion: novae produce up to 30% of the 26Al in Milky Way
Pre-solar grains
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SiC Grain from Murchison meteorite
~1 micron
L. Nittler, www.presolargrains.net
www.dtm.ciw.edu/users/lrn/psg/types.html
Pre-solar nova grain candidates
Andrew M. Davis, PNAS (2011)C. Wrede, HUGS, May 2019
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Pre-solar nova grain candidates
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Andrew M. Davis, PNAS (2011)
What should a SiC nova grain look like?
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J. Jose et al. Astrophys. J. 612, 414 (2004)
Competition between 30P(p,g)31S and 2.5 min b decay of 30P determines 30Si/28Si isotopic ratio expected for nova grains.
Populating 30P(p,g)31S resonances with 31Cl decay
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NSCL Experiment 12028
M. B. Bennett et al., Phys. Rev. Lett. 116, 102502 (2016)
M. B. Bennett, Ph.D. thesis (MSU, 2016)
Production of 31Cl at NSCL
• 150 MeV/u, 75 pnA 36Ar beam, 1.63 mg/cm2 Be target
• 95% pure beam of up to 9000 31Cl ions per second
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M. B. Bennett et al., Phys. Rev. Lett. 116, 102502 (2016)
M. B. Bennett, Ph.D. thesis (MSU, 2016) 18
CloverShare HPGe array
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M. B. Bennett et al., Phys. Rev. Lett. 116, 102502 (2016)
M. B. Bennett, Ph.D. thesis (MSU, 2016)
31Cl(b g) data
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M. B. Bennett et al., Phys. Rev. Lett. 116, 102502 (2016)
M. B. Bennett, Ph.D. thesis (MSU, 2016)
31Cl b decay scheme: a new resonance!
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M. B. Bennett et al., Phys. Rev. Lett. 116, 102502 (2016)
M. B. Bennett, Ph.D. thesis (MSU, 2016)
Thermonuclear 30P(p,g)31S reaction rate
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M. B. Bennett et al., Phys. Rev. Lett. 116, 102502 (2016)
M. B. Bennett, Ph.D. thesis (MSU, 2016)
New state could be dominant 30P(p,g)31S resonance in novae. Need to measure
proton emission branch and lifetime to determine resonance strength…
Low-energy b delayed charged particles
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Measure 31Cl(b p) 31S through new 30P(p,g)31S resonance to determine p/
Challenge: usual method using Si detectors yields massive b-particle background
A. Saastamoinen, Ph.D. thesis (2011, Jyvaskyla)
Solution: gas-filled detector
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Y. Giomataris et al., NIM A 376, 29 (1996)
E. Pollacco et al., NIM A 723, 102 (2013)
Micropattern gas amplifier: principle of operation
b particles deposit less energy in gas, reducing background
New GADGET system at NSCL
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NSCL E17024 goal: measure 31Cl(b p) 31S through new 30P(p,g)31S resonance and determine p/
GADGET: Gas Amplifier Detector with Germanium Tagging
GADGET commissioning experiment
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Proton Detector with part of SeGA around itMicromegas
NSCL E17023: May 2018
GADGET Commissioning decay: 25Si(bp)24Mg
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NSCL E17023: May 2018
Preliminary 31Cl(b p)31S spectrum
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31Cl(b p)31S peak detected at ~260 keV will yield p/. Also acquired data to determine 31S lifetimes at TRIUMF in Fall 2018 potential resonance strength.
NSCL E17024: November 2018
X-ray burst light curve
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RXTE; Galloway et al., Astrophys. J. 179, 360 (2008)
X-ray burst
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Break out from hot CNO cycles
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M. Wiescher et al., J. Phys. G 25, R133 (1999)
C. Iliadis, AIP Conf. Proc. 1213, 3 (2010)
rp process
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Figure: H. Schatz
Which reactions impact the X-ray burst light curve?
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R. Cyburt et al., Astrophys. J. 830, 55 (2016)
Key 15O(a,g)19Ne resonance
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B. Davids et al., Astrophys. J. 735, 40 (2011)
W. P. Tan et al., Phys. Rev. C 72, 041302 (2005)
R. Kanungo et al., Phys. Rev. C 74, 045803 (2006)
B. Davids et al., Phys. Rev. C 67, 065808 (2003)
W. P. Tan et al., Phys. Rev. Lett. 98, 242503 (2007)
a
g
1~
New idea: b decay of 20Mg to probe key 15O(a,g)19Ne resonance
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C. Wrede et al., Phys. Rev. C 96, 032801(R) (2017)
20Mg(b p g) spectra(NSCL E14066)
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C. Wrede et al., Phys. Rev. C 96, 032801(R) (2017)
4033-keV 15O(a,g)19Ne resonance is populated in 20Mg b decay!
GADGET upgrade to TPC (“GADGET II”)
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Measure 20Mg(b p a)15O through 4033-keV 15O(a,g)19Ne resonance to determine a/ (NSCL E18033: 2020)
Geant4 simulation by D. Perez-Loureiro
C. Wrede et al., Phys. Rev. C 96, 032801(R) (2017)
Summary of experiments
• 26P b decay experiment to constrain 26Al production in novae via 25Al(p,g)26Si reaction rate
• 31Cl b decay experiments to ID candidate pre-solar nova grains via 30P(p,g)31S reaction rate
• 20Mg b decay experiments to investigate CNO-cycle break out via 15O(a,g)19Ne reaction in type I x-ray bursts
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For NSCL E10034, E12028, E14066 (beta-gamma work):
Colorado School of Mines
Joint Institute for Nuclear Astrophysics
McMaster University
Michigan State University
National Superconducting Cyclotron Laboratory
University of Notre Dame
Oak Ridge National Laboratory
Universitat Politècnica de Catalunya
University of Southern Indiana
University of Tennessee
Texas A&M University
University of Washington
Yale University
For NSCL E17023, E17024, E18033 (GADGET work):
CEA-Saclay
Michigan State University
National Superconducting Cyclotron Laboratory
Texas A&M University
Collaborating institutions
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Broader summary
• It is not always possible to directly measure nuclear cross sections and resonance strengths for charged particle reactions at astrophysical energies
• There is a wide variety of indirect experimental techniques that can provide the necessary nuclear structure and reaction information to determine thermonuclear rates at the relevant energies
• Today, we have focused on one particular method employed at NSCL and FRIB
• Next: direct measurements of neutron-induced reactions
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Thank you for your attention!