Surrogate neutron capture reaction prospects for r-process nuclei Jolie A. Cizewski Rutgers Universit FRIB and the GW170817 Kilonova Facility for Rare Isotope Beams, 23-27 July 2018 Surrogate neutron capture reaction prospects for r-process nuclei J.A.C.(1), Brett Manning(1), Andrew Ratkiewicz(1,2), Jutta Escher(2), Jason Burke(2), Alex Lepailleur(1), Goran Arbanas(3), Gregory Potel(4), Steve Pain(3) , David Walter(1) (1) Rutgers Universit (2) Lawrence Livermore Natonal Laboratry (3) Oak Ridge Natonal Laboratry (4) Michigan Stat Universit & FRIB and the ORRUBA, STAR-LiTeR and GODDESS collaborations Funded in part by the U.S. Department of Energy National Nuclear Security Administration & Office of Nuclear Physics and the National Science Foundation FRIB TA July 2018 ANRV352-AA46-08 ARI 15 July 2008 11:46 2. HEAVY ELEMENT FORMATION Stellar fusion of elements heavier than iron is endothermic: It requires energy. Also, Coulomb barriers for charged-particle reactions increase at heavy proton number. As a result, the nuclei beyond the Fe group are generally not formed in charged-particle fusion but instead are created in n-capture processes; there are no Coulomb barriers. Neutrons are captured onto nuclei that can then β decay if they are unstable, transforming neutrons into protons. In this manner, element production progresses through the heaviest elements of the Periodic Table.This process is defined as slow (rapid) if the timescale for neutron capture, τ n, is slower (faster) than the radioactive decay timescale, for unstable nuclei. Generally we refer to these as the s-process or the r-process. The r-process and s-process were initially described and defined in 1957 by Burbidge et al. (1957) and Cameron (1957a,b). The s-process (τ τ ) is defined by virtue of the long times n ≫ β (hundreds or thousands of years) between successive neutron captures on target nuclei. It thus operates close to the so-called valley of β-stability, as illustrated in Figure 1 (Moller,¨ Nix & Kratz 1997, their figure 16). Consequently the properties (e.g., masses and half-lives) of the stable and long-lived nuclei involvedUnderstanding in the s-process can be r-process obtained experimentally. nucleosynthesis As the s-process depends on nuclear data 120 100 r-process abundance Sneden, Cowan, Gallino, Annu. Rev. Astron. Astrophys. 46:241-288 (2008) 200 0 80 18 ) 1 Z 0 10 16 A) 40 N 0 1 r , 10 60 (Si = 10 0 12 Mass number ( –1 log(T s–1) 10 100 6 ) –2 1.0 Access provided by Rutgers University Libraries on 03/13/17. For personal use only. Proton number ( Proton 80 40 10 Need nuclear data 0.5 Annu. Rev. Astron. Astrophys. 2008.46:241-288. Downloaded from www.annualreviews.org 0.0 § Masses –0.5 § Reaction, decay & direct–1.0 measurements 20 –1.5 § Beta-decay half lives –2.0 § Beta-delayed neutron probabilities–2.5 0 § Nuclear structure ç reaction, decay & theory 0 20 40 60 80 100 120 140 160 Neutron§ (numbern,γ) rates (N) ç reaction exp & theory studies FRIB TA July 2018 Figure 1 Chart of the nuclides showing proton number versus neutron number after Moller,¨ Nix & Kratz (1997). Black boxes indicate stable nuclei and define the so-called valley of β-stability. Vertical and horizontal lines indicate closed proton or neutron shells. The magenta line indicates the so called r-process path, with the magenta boxes indicating where there are final stable r-process isotopes. Color shading denotes the timescales for β decay for nuclei and the jagged black line denotes the limits of experimentally determined nuclear data at the time of their article. www.annualreviews.org Neutron-Capture Elements in the Early Galaxy 243 • ANRV352-AA46-08 ARI 15 July 2008 11:46 2. HEAVY ELEMENT FORMATION Stellar fusion of elements heavier than iron is endothermic: It requires energy. Also, Coulomb barriers for charged-particle reactions increase at heavy proton number. As a result, the nuclei beyond the Fe group are generally not formed in charged-particle fusion but instead are created in n-capture processes; there are no Coulomb barriers. Neutrons are captured onto nuclei that can then β decay if they are unstable, transforming neutrons into protons. In this manner, element production progresses through the heaviest elements of the Periodic Table.This process is defined as slow (rapid) if the timescale for neutron capture, τ n, is slower (faster) than the radioactive decay timescale, for unstable nuclei. Generally we refer to these as the s-process or the r-process. The r-process and s-process were initially described and defined in 1957 by Burbidge et al. (1957) and Cameron (1957a,b). The s-process (τ τ ) is defined by virtue of the long times n ≫ β (hundreds or thousands of years) between successive neutron captures on target nuclei. It thus operates close to the so-called valley of β-stability, as illustrated in Figure 1 (Moller,¨ Nix & Kratz 1997, their figure 16). Consequently the properties (e.g., masses and half-lives) of the stable and long-lived nuclei involved in the s-process can ber-process obtained experimentally. nucleosynthesis As the s-process depends on104 (n,γ) ratesM.R. Mumpower and et al. / Progress site in Particle of and Nuclear r Physicsprocess 86 (2016) 86–126 120 100 r-process abundance 200 0 N=82 80 18 ) 1 Z 0 10 16 A) 40 N 0 1 r , 10 60 (Si = 10 0 12 Mass number ( –1 log(T s–1) 10 100 6 ) –2 1.0 Access provided by Rutgers University Libraries on 03/13/17. For personal use only. Proton number ( Proton 80 40 10 0.5 Annu. Rev. Astron. Astrophys. 2008.46:241-288. Downloaded from www.annualreviews.org 0.0 –0.5 –1.0 20 –1.5 –2.0 –2.5 0 0 20 40 60 80 100 120 140 160 M.R. Mumpower, R. Surman, G.C. McLaughlin, Neutron number (N) FRIBA. Aprahamian TA July 2018, PPNP 86, 86 (2016) Figure 1 Fig. 16. Important neutron capture rates in four astrophysical environments (a) low entropy hot wind, (b) high entropy hot wind, (c) cold wind and 4 (d) neutron star merger with stable isotopes in black. Estimated neutron-rich accessibility limit shown by a black line for FRIB with intensity of 10− Chart of the nuclides showing proton number versusparticles neutron per second number [206]. after Moller,¨ Nix & Kratz (1997). Source: Simulation data from [122]. Black boxes indicate stable nuclei and define the so-called valley of β-stability. Vertical and horizontal lines indicate closed proton or neutron shells. The magenta line indicates the so called r-process path, with the The complete sensitivity study results of Figs. 13–16 are included in a table in the Appendix. Sensitivity measures F are magenta boxes indicating where there are final stablestatedr-process explicitly isotopes. wherever F Color> 0.01; an shading asterisk is denotes used to indicate the 0 < F < 0.01. Since the studies of masses started from a timescales for β decay for nuclei and the jagged blackdifferent line denotes baseline nuclear the limits data set of than experimentally the other studies, the determined sets of nuclei included in each study do not necessarily overlap. nuclear data at the time of their article. If a nucleus is not included in a particular study it is indicated by a dash in the table. Some caveats regarding the table: (1) All studies are for main A > 120 r processes. F measures are listed for some nuclei with A < 120; these indicate the impact of their nuclear properties on A > 120 nucleosynthesis only. (2) The sensitivity measures F are global measures. The largest measures correspond to either large local abundance pattern changes or somewhat smaller changes throughout the pattern, or some combination of the two. Modest local changes are not captured by this measure. (3) The four sets of astrophysical conditions chosen for the studies are meant to be representative of a variety of possible www.annualreviews.org Neutron-Capture Elements in the Early Galaxy 243 scenarios but are by no• means exhaustive. Different astrophysical conditions will produce different F measures, and some nuclei labeled with asterisks in the table may be important in other scenarios, or with a different choice of baseline nuclear data. ANRV352-AA46-08 ARI 15 July 2008 11:46 2. HEAVY ELEMENT FORMATION Stellar fusion of elements heavier than iron is endothermic: It requires energy. Also, Coulomb barriers for charged-particle reactions increase at heavy proton number. As a result, the nuclei beyond the Fe group are generally not formed in charged-particle fusion but instead are created in n-capture processes; there are no Coulomb barriers. Neutrons are captured onto nuclei that can then β decay if they104 are unstable, transformingM.R. neutrons Mumpower into et al. protons./ Progress in ParticleIn this and manner, Nuclear Physics element 86 (2016) 86–126 production progresses through the heaviest elements of the Periodic Table.This process is defined as slow (rapid) if the timescale for neutron capture, τ n, is slower (faster) than the radioactive decay timescale, for unstable nuclei. Generally we refer to these as the s-process or the r-process. The r-process and s-process were initially described and defined in 1957 by Burbidge et al. (1957) and Cameron (1957a,b). The s-process (τ τ ) is defined by virtue of the long times n ≫ β (hundreds or thousands of years) between successive neutron captures on target nuclei. It thus operates close to the so-called valley of β-stability, as illustrated in Figure 1 (Moller,¨ Nix & Kratz 1997, their figure 16).