Skip to content
Reaction atlas · s-process

Radiative capture · Weak component (massive stars)

62Ni(n,γ)63Ni

: nickel‑62 + neutron → nickel‑63 + gamma rayHow to read the notation

On this page

Nickel-62 captures a neutron. In massive stars this capture is one of the steps that hold back the weak s-process, and it affects what is made after it.

In massive stars there are too few neutrons per iron seed for the s-process to reach far, and the flow of matter stays in the region from iron to strontium. There, each capture with a small cross section holds back the flow and lowers the production of every heavier nucleus. Nickel-62 is one of these steps, which is why its stellar cross section, in particular at the high temperatures of carbon-burning shells, changes the predicted production of the heavier nuclei, and of copper in particular.

Facts

How well known
Known to about 5%, from neutron-beam measurements at CERN, which lowered the value for the hottest burning in massive stars.
Live evaluation
No live evaluation yet · Evaluations
Reaction rates
Explore the rates →
Q-value · energy released
6.838 MeV
Thermal energy kT
about 26–90 keV, the energy of a gas at 300–1000 million kelvin
By stellar site
  • 26 keVmassive star, core helium burning, 0.3 GK
  • 90 keVmassive star, shell carbon burning, 1.04 GK
Why no Gamow window
A neutron feels no Coulomb barrier, so there is no Gamow window: the relevant energies are those of the thermal distribution itself, around kT.
Product 63Ni
radioactive, t½ = 101 yr
Kind
Radiative capture

How it was measured

1 measurement, 2014Show the list
  1. 2014

    n_TOF, CERNCERN

    Neutron beams and time of flight · resonances up to 200 keV (neutron energy)

    42 resonances analysed; MACS for kT = 5–100 keV with 4.5% total uncertainty, up to a factor 1.6 below KADoNiS at high kT. [1]

Measurements (EXFOR)

Every dataset EXFOR holds for this reaction, drawn by the energies it covers, against the energies a star uses.

56 datasets in 27 EXFOR entries, 1952–2014 · 23 without an energy range, not drawn

Temperature
Lowest energy in EXFOR
24.6 meV
Cote et al., 1964; Doilnitsyn, 1965; Sims et al., 1970; Alpizar-Vicente et al., 2008 · dσ/dΩ · 13816.006
Maxwellian averages measured
15 sets
kT from 5 keV to 100 keV
Rate from energies not in EXFOR
< 0.01%
at kT = 25.9 keV, smooth estimate
10 meV100 meV1 eV10 eV100 eV1 keV10 keV100 keV1 MeVEnergy, or kT for a Maxwellian average (keV)kT = 25.9 keVσdσ/dΩωγMACSother
  • Energies that matter at kT = 25.9 keV
  • Outlined bars are shown but not counted (the rule is under “How these numbers are made”).
  • A diamond is a dataset at a single energy. Bars running off the right edge continue to higher energies.
The datasets of the gap map, by quantity
The datasets of the gap map, by quantity
QuantityDatasetsE_cm range (keV)
σcross section524.6 meV – 358 keV
dσ/dΩangular distribution124.9 meV – 24.9 meV
ωγresonance strength23.94 keV – 4.53 keV
MACSMaxwellian average155 keV – 100 keV
…other1024.6 meV – 295 keV
How these numbers are made

Lowest measured energy, everywhere in the data explorer: the lowest centre-of-mass energy at which a dataset in EXFOR measures the reaction itself (cross section, S-factor, angular distribution, yield or resonance strength), judged point by point. A point counts when it is a value, not an upper or lower limit, when it lies at least one standard deviation above zero, and when its energy is physical: at least 1 keV for charged particles, and not below the threshold of an endothermic reaction. Not counted: extrapolated, calculated, evaluated or derived values; superseded, deleted or preliminary data; ratios; a single S-factor value, which in EXFOR is a fit result; and indirect methods (Trojan horse, Coulomb dissociation, ANC, surrogate reactions), recognized from EXFOR's method and analysis codes, their text and the title. Frame and unit errors of EXFOR are corrected first, and values the literature shows to be upper limits are read as limits, from a list that gives the evidence for each. Datasets that reach the same energy within 0.5% are all credited, earliest first. Rate from energies not in EXFOR: the share of the rate integrand at that temperature outside the energy ranges the counted datasets cover (from their lowest measured point to their highest), with a constant S-factor (σ ∝ S(E₀)/E · e^−2πη, so the integrand is e^(−E/kT − 2πη)); for a neutron capture, σ ∝ 1/v. Resonances make the real integrand lumpy, so read it as a smooth baseline.

Details

How well known, in detail: Known to 4.5% at kT = 30 keV from n_TOF; the n_TOF data lowered the cross section at the higher temperatures of carbon burning by up to a factor 1.6.

At n_TOF the capture kernels of 42 resonances of 62Ni were analysed up to 200 keV, and Maxwellian-averaged cross sections were calculated for kT = 5–100 keV with a total uncertainty of 4.5%. They agree with the KADoNiS value at kT = 30 keV but are up to a factor 1.6 lower at higher temperatures, which matters for shell carbon burning at kT ≈ 90 keV (Lederer et al. 2014).

Evaluations

Compilations that combine the data into a recommended rate.

  • —Z. Y. Bao et al., At. Data Nucl. Data Tables 76, 70 (2000) [2]
  • —I. Dillmann et al., Proc. Int. Conf. on Nuclear Data for Science and Technology 2007 (EDP Sciences, 2008), p. 575 [3]

Related reactions

References

  1. 1.
  2. 2.

    Z. Y. Bao, H. Beer, F. Käppeler, F. Voss, K. Wisshak, T. Rauscher

    Neutron cross sections for nucleosynthesis studies

    At. Data Nucl. Data Tables 76, 70 (2000) · 10.1006/adnd.2000.0838

  3. 3.

    I. Dillmann et al.

    New stellar (n,γ) cross sections and the "Karlsruhe Astrophysical Database of Nucleosynthesis in Stars"

    Proc. Int. Conf. on Nuclear Data for Science and Technology 2007 (EDP Sciences, 2008), p. 575 (2008) · 10.1051/ndata:07303 · arXiv:0806.2076

How to cite this page

J. Skowronski, 62Ni(n,γ)63Ni, in Reaction atlas, 2026-10-12, https://jskowron.eu/atlas/62Ni-ng-63Ni.

Cite the date you used; it is the last change to this page.

Something wrong or missing? Report an error (opens a new issue on GitHub) · Suggest a reaction (opens a new issue on GitHub)