From Stellar Death to Element Birth

the role of nuclear reactions in supernovae explosions

 

Thanassis Psaltis (@psaltistha)
Triangle Universities Nuclear Laboratory & North Carolina State University
 

April 20, 2023
Cyclotron Seminar | Texas A&M University


 

Image Credit: NASA/CXC/SAO

Acknowledgements

Alan Chen   Almudena Arcones   Melina Avila   Barry Davids   Camilla Juul Hansen   Annika Lennarz   Richard Longland   Peter Mohr   Fernando Montes   Chris Ruiz

+ many graduate students!















Image Credit: NASA/CXC/SAO

The periodic table from
a Galactic Chemical Evolution perspective

C. Kobayashi, A. Karakas and M. Lugaro, Astrophys. J 900, 179 (2020)

 

 

 

 

 

 

 

HD 122563 (DSS2/ Aladin Sky Atlas)

What do the oldest stars reveal to us?

See also: C. Sneden, J. J. Cowan and R. Gallino, Annu. Rev. Astron. Astrophys. 46, 241 (2008)
⚠️ Solar r-process = Solar total - Solar s-process - Solar γ-process

How many processes contribute to the production of elements between Sr and Ag?

The periodic table from
a Galactic Chemical Evolution perspective

C. Kobayashi, A. Karakas and M. Lugaro, Astrophys. J 900, 179 (2020)

LEPP /l'əp/ n.
(Light Element Primary Process)

1. A primary process that occurs in low-metallicity massive stars, different from the s- and r-process and produce the lighter heavy elements.

C. Travaglio et al. Astrophys. J 601, 864 (2004)

$\boldsymbol{\nu p}$-process

C. Fröhlich et al., Phys. Rev. Lett. 96, 142502 (2006) • J. Pruet et al., Astrophys. J. 644, 1028 (2006) • S. Wanajo, Astrophys. J 647, 1323 (2006) • S. Wanajo, H.-T. Janka and S. Kubono, Astrophys. J. 729, 46 (2011) • N. Nishimura et al., Mon. Notices Royal Astron. Soc. 489, 1379 (2019) | Electron fraction, $Y_e = (n_p)/(n_p+n_n)$

How do we identify
important reactions?

Nuclear reaction networks

are an essential tool for Nuclear Astrophysics

W. R. Hix and F.-K. Thielemann, J. Comput. Appl. Math 109, 321 (1999)
C. Jiang et al., New J. Phys. 23 083035 (2021)

Sensitivity studies motivate experiments

Same model, but different nuclear input!

S. Wanajo et al., Astrophys. J 729, 46 (2011)

Why study the $\mathrm{^7Be(\alpha,\gamma)^{11}C}$ reaction?

  • Affects the number of $\mathrm{^{56}Ni}$ during the $\nu p$-process, and the production of $A \sim 100-110$ neutron-deficient species.
    S. Wanajo, H.-T. Janka and S. Kubono, Astrophys. J. 729, 46 (2011)

  • Its rate is not well known over the relevant energy region.
    Only 2 measured resonances in the present reaction rate.
    Y. Hu et al. Nucl. Phys. A 918, 61 (2013) • G. Hardie et al., Phys. Rev. C 29, 1199 (1984)
    M. Wiescher et al., Phys. Rev. C 28, 1431 (1983) • H. Yamaguchi et al., Phys. Rev. C 87, 034303 (2013)

How to measure the $\mathrm{^7Be(\alpha,\gamma)^{11}C}$
reaction in a lab

Inverse kinematics in the laboratory frame.
C.R. Brune and B. Davids, Annu. Rev. Nucl. Part. 65, 87 (2015) • C. Rolfs and C.A. Barnes, Annu. Rev. Nucl. Part. 40, 45 (1990)

The DRAGON recoil separator 🐲

D.A. Hutcheon et al., Nucl. Instr. Meth. Res. A 498, 190 (2003)

Reactions in inverse kinematics: the challenge

DRAGON's acceptance $ -~\mathrm{\theta_{DRAGON} \sim 21~mrad}$

$\mathrm{^7Be(\alpha,\gamma)^{11}C - \theta_{r,max} \sim 43~mrad}$

C. Ruiz, U. Greife and U. Hager, Eur. Phys. J. A 50, 99 (2014)

Can DRAGON can measure $\omega \gamma$ of reactions
with $\mathrm{\theta_{r,max}>\theta_{DRAGON}}$ ?



Proof-of-principle test: $\mathrm{^6Li(\alpha,\gamma)^{10}B}$
A. Psaltis et al., Nucl. Instrum. Methods Phys. Res. A 987, 164828 (2021)

DRAGON can measure $\omega \gamma$ of reactions with $\mathrm{\theta_{r,max}>\theta_{DRAGON}}$

$\mathrm{\omega \gamma_{lit}= (0.228 \pm 0.038)~eV}$
$\mathrm{\omega \gamma_{DRA}= 0.225^{+0.025}_{-0.035} (stat.) \pm 0.030 (syst.)~eV}$

A. Psaltis et al., Nucl. Instrum. Methods Phys. Res. A 987, 164828 (2021)

$\mathrm{^7Be(\alpha,\gamma)^{11}C}$

The DRAGON recoil separator 🐲

D.A. Hutcheon et al., Nucl. Instr. Meth. Res. A 498, 190 (2003)

$\mathrm{^7Be(\alpha,\gamma)^{11}C}$ PID plot

A. Psaltis et al., Phys. Rev. C 106, 045805 (2022)

$\mathrm{^7Be(\alpha,\gamma)^{11}C}$ BGO plot

A. Psaltis et al., Phys. Rev. Lett. 129, 162701 (2022)

$\mathrm{^7Be(\alpha,\gamma)^{11}C}$ resonance strength results

A. Psaltis et al., Phys. Rev. Lett. 129, 162701 (2022) • A. Psaltis et al. Phys. Rev. C 106, 045805 (2022)

Calculate the new $\mathrm{^7Be(\alpha,\gamma)^{11}C}$ reaction rate

Treat $(\omega \gamma, E_{r_i},\cdots)$ as distributions and use Monte Carlo techniques to extract a statistically meaningful reaction rate.

R. Longland et al., Nuc. Phys. A 841, 1 (2010) • A.L. Sallaska et al., Astrophys. J Suppl. Ser. 207, 18 (2013)
The code is available at $\texttt{https://github.com/rlongland/RatesMC}$

The new $\mathrm{^7Be(\alpha,\gamma)^{11}C}$ reaction rate

We decreased the rate uncertainty to $\approx 10\%$ over $T= 1.5-3$ GK

The new $\mathrm{^7Be(\alpha,\gamma)^{11}C}$ reaction rate

No effect in $\nu p$-process nucleosynthesis

Take-home message #1


We measured the $\mathrm{^7Be(\alpha,\gamma)^{11}C}$ reaction using DRAGON and constrained its rate over $\nu p$-process energies.

weak $\boldsymbol{r}$-process ($\boldsymbol{\alpha}$-process)

S. Woosley & R.D. Hoffman, Astrophys. J 395, 202 (1992) • S. Wanajo et al., Astrophys. J. 554, 578 (2001) • A. Arcones & F. Montes, Astrophys. J 731, 5 (2011) • J. Bliss et al., Phys. Rev. C 101, 055807 (2020)

What is the impact of the
$\mathbf{(\alpha,xn)}$ reactions
in the weak $r$-process?

How well do we know the $(\alpha,xn)$ reaction rates?

The $(\alpha,xn)$ reaction rates are sensitive to the $\alpha$-optical model potential and can differ by up to two orders of magnitude.

J. Pereira and F. Montes, Phys. Rev. C 93, 034611 (2016) • P. Mohr, Phys. Rev. C 94, 35801 (2016)

The impact of new $(\alpha,n)$ reaction rates to
elemental abundances

Same model, but different $(\alpha, xn)$ reaction rates!

A. Psaltis et al., Astrophys. J 935, 27 (2022)

The impact of new $(\alpha,n)$ reaction rates
to elemental abundance ratios

A. Psaltis et al., Astrophys. J 935, 27 (2022)

Combine observations, astrophysical modeling and nuclear physics uncertainties

A. Psaltis et al., Astrophys. J 935, 27 (2022)

Which are the most important
$\mathbf{(\alpha,xn)}$ reactions
for the weak $r$-process?

Finding the most important $(\alpha,n)$ reactions
for the weak $r$-process

The most important $(\alpha,n)$ reactions
for the weak $r$-process

  1. $\mathrm{^{84}Se}$, $\mathrm{^{87-89}Kr, ^{93}Sr}$
    Affect many elemental ratios in many astrophysical conditions

  2. $\mathrm{^{86}Br,^{86, 90}Kr, ^{87-89}Rb, ^{91, 92, 94}Sr, ^{94}Y}$
    Affect few elemental ratios in many astrophysical conditions

  3. $\mathrm{^{85}Se, ^{85}Br}$
    Affect many elemental ratios in few astrophysical conditions

  4. $\mathrm{^{63}Co, ^{67}Cu, ^{79, 81}Ga, ^{76}Zn, ^{80, 82}Ge, ^{83}As}$
    $\mathrm{^{87, 90, 91}Rb, ^{88-90}Sr, ^{95, 96}Y, ^{96-98}Zr}$
    Affect few elemental ratios in few astrophysical conditions

Take-home message #2


We combined observations, astrophysical modeling and nuclear theory to study the impact of $(\alpha,xn)$ reactions to the weak $r$-process

Can we study these $\mathbf{(\alpha,xn)}$ reactions in the lab?

Most of the relevant beams are accessible now!

FRIB expected beam rates for PAC2 experiments

First measurement of the $\boldsymbol{\mathrm{^{93}Sr}(\alpha,xn)\mathrm{^{96-x}Zr}}$ reaction

$\mathrm{^{93}Sr}(\alpha,xn)\mathrm{^{96}Zr}$ at Argonne with MUSIC

M. L. Avila et al., Nucl. Instrum. Methods Phys. Res A 859, 63 (2017)

  • Re-accelerated $\mathrm{^{93}Sr}$ beam from $\nu$CARIBU.
  • Close to 100% efficiency due to its segmented anode structure. Self-normalizing, no additional monitor detectors are needed.
  • Measure a large range of excitation functions of angle and energy integrated cross sections using a single beam energy.
Proposal #1923, PI: Psaltis, co-PI: Ong

Active Targets will play a major role in measuring all the important $(\alpha,xn)$ cross sections for the weak $r$-process!

🤠 yeehaw

Measurement of $\boldsymbol{(\alpha,xn)}$ reactions at FRIB using SECAR

$\mathrm{^{84}Se}(\alpha,n)\mathrm{^{87}Kr}$ and $\mathrm{^{87}Kr}(\alpha,n)\mathrm{^{90}Sr}$
at FRIB with SECAR

G. Berg et al., Nucl. Instrum. Methods Phys. Res A 877, 87 (2018)

  • Large acceptance allows for measurement of $(\alpha,n)$ reactions
  • JENSA jet target & LENDA neutron array
  • Focal plane setup: 2 MCP position sensitive TOF detectors, Ionization Chamber, Si-detector

Secrets in the stardust 💫

Isotopic abundance patterns detected in presolar grains (SiC-X) could reveal core-collapse supernova nucleosynthesis signatures!

Pellin, M. J. et al., LPSC 37, 2041 (2006)
P. R. Heck et al., PNAS 117, 1884 (2020)

What we expect in the near future

More measurements on the key $(\alpha, xn)$ reactions and observations of old stars will help us constrain the production site of the light heavy elements, between Sr and Ag.

Take-home messages

  1. We measured the $\mathrm{^7Be(\alpha,\gamma)^{11}C}$ reaction using DRAGON and constrained its rate over $\nu p$-process energies.

  2. We combined observations, astrophysical modeling and nuclear theory to study the impact of $(\alpha,xn)$ reactions to the weak $r$-process.

  3. Experiments in the current and next-generation facilities, along with multimessenger observations and theoretical modeling will help us better understand the origin of the heavy elements.

Thank you! 🤠

Slides available at
http://psaltisa.github.io/talks