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Creators/Authors contains: "Stech, E"

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  1. Free, publicly-accessible full text available February 1, 2027
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  6. Abstract The$$^{90}$$ 90 Zr(p,$$\gamma $$ γ )$$^{91}$$ 91 Nb reaction is one of the important reactions in the$$A\approx 90$$ A 90 mass region and part of the nucleosynthesis path responsible for production of$$^{92}$$ 92 Mo during the$$\gamma $$ γ -process. Discrepant data in the literature provide a cross section that varies up to 30% within the Gamow window for the$$^{90}$$ 90 Zr(p,$$\gamma $$ γ )$$^{91}$$ 91 Nb reaction. Thus, the cross section measurements of$$^{90}$$ 90 Zr(p,$$\gamma $$ γ )$$^{91}$$ 91 Nb reaction were revisited using the$$\gamma $$ γ -summing technique. The results are consistent with the lower-value cross sections found in the literature. Based on the new data an updated reaction rate for$$^{90}$$ 90 Zr(p,$$\gamma $$ γ )$$^{91}$$ 91 Nb is provided that is up to 20% higher than that obtained from thenon-smokercode. 
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  7. Here we report on the direct measurement of the resonance strengths of the E R lab = 647 keV and 1842 keV resonances in the Ca 40 ( p , γ ) Sc 41 reaction. At novae temperatures, 0.2 < T 9 < 0.7 , the Ca 40 ( p , γ ) Sc 41 reaction is governed by the low energy resonance at E R lab = 647 keV , whereas the E R lab = 1842 keV resonance serves as a normalization standard for nuclear reaction experiments within the astrophysically relevant energy range. For the E R lab = 647 keV resonance, we obtain a resonance strength ω γ = ( 2.51 ± 0 . 09 stat ± 0 . 22 syst ) meV , with an uncertainty a factor of 2.5 smaller than the previous direct measurement value. For the E R lab = 1842 keV resonance, we obtain a resonance strength ω γ = ( 0.148 ± 0 . 006 stat ± 0 . 013 syst ) eV , which is consistent with previous studies but deviates by 2 σ from the most recent measurement. Our results suggest Ca 40 to be a strong waiting point in the nucleosynthesis path of oxygen-neon (ONe) novae. Published by the American Physical Society2025 
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    Free, publicly-accessible full text available February 1, 2026