Constraining the 22Ne(α,γ)26Mg and 22Ne(α,n)25Mg reaction rates using sub-Coulomb α-transfer reactions

Jayatissa, H.; Rogachev, G. V.; Goldberg, V. Z.; Koshchiy, E.; Christian, G.; Hooker, J.; Ota, S.; Roeder, B. T.; Saastamoinen, A.; Trippella, O.; Upadhyayula, S.; Uberseder, E.

doi:10.1016/j.physletb.2020.135267

Cited by 27 publications

(91 citation statements)

References 29 publications

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“…The new evaluation of the reaction rate, based on spin-parity assignments by Jayatissa et al (2020) combined with data from Ota et al (2020), resulted in lower rates than previous evaluations, especially at low temperatures (see Figure 7). The lower rate is also the result of excluding an excited state at E x 11.112 MeV, corresponding to E α,lab 598 keV, observed by Massimi et al (2017) and not observed in these studies.…”

Section: State-of-the-artmentioning

confidence: 76%

“…The continued interest in this reaction is demonstrated by two very recent experimental studies by Ota et al (2020) and Jayatissa et al (2020) with α transfer reactions: Ota et al (2020) studied the 22 Ne( 6 Li, d) 26 Mg in inverse kinematics, detecting outgoing deuterons and 25,26 Mg in coincidence. In addition, Jayatissa et al (2020) studied the 22 N( 7 Li, t) 26 Mg reaction.…”

Section: State-of-the-artmentioning

confidence: 99%

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The Study of Key Reactions Shaping the Post-Main Sequence Evolution of Massive Stars in Underground Facilities

Ferraro

Ciani

Boeltzig

et al. 2021

Front. Astron. Space Sci.

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The chemical evolution of the Universe and several phases of stellar life are regulated by minute nuclear reactions. The key point for each of these reactions is the value of cross-sections at the energies at which they take place in stellar environments. Direct cross-section measurements are mainly hampered by the very low counting rate and by cosmic background; nevertheless, they have become possible by combining the best experimental techniques with the cosmic silence of an underground laboratory. In the nineties, the LUNA (Laboratory for Underground Nuclear Astrophysics) collaboration opened the era of underground nuclear astrophysics, installing first a homemade 50 kV and, later on, a second 400 kV accelerator under the Gran Sasso mountain in Italy: in 25 years of experimental activity, important reactions responsible for hydrogen burning could have been studied down to the relevant energies thanks to the high current proton and helium beams provided by the machines. The interest in the next and warmer stages of star evolution (i.e., post-main sequence and helium and carbon burning) drove a new project based on an ion accelerator in the MV range called LUNA-MV, able to deliver proton, helium, and carbon beams. The present contribution is aimed to discuss the state of the art for some selected key processes of post-main sequence stellar phases: 12C(α,γ)16O and 12C+12C are fundamental for helium and carbon burning phases, and 13C(α,n)16O and 22Ne(α,n)25Mg are relevant to the synthesis of heavy elements in AGB stars. The perspectives opened by an underground MV facility will be highlighted.

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Section: State-of-the-artmentioning

confidence: 76%

Section: State-of-the-artmentioning

confidence: 99%

The Study of Key Reactions Shaping the Post-Main Sequence Evolution of Massive Stars in Underground Facilities

Ferraro

Ciani

Boeltzig

et al. 2021

Front. Astron. Space Sci.

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show abstract

“…Adsley et al [13] relaxed the constraints on the α-particle partial widths since the states at these excitation energies are not resolved and it is not clear to which 26 Mg state or states the transfer reaction proceeds. The updated sub-Coulomb transfer data of Jayatissa et al [15] suggest that a cluster state exists at around E x = 10.8 MeV but it is not clear which of the three states in 26 Mg is of cluster character. We adopt the widths from Jayatissa et al [15] for the computation of the recommended reaction rate.…”

Section: Combining the Experimental Datamentioning

confidence: 97%

“…The updated sub-Coulomb transfer data of Jayatissa et al [15] suggest that a cluster state exists at around E x = 10.8 MeV but it is not clear which of the three states in 26 Mg is of cluster character. We adopt the widths from Jayatissa et al [15] for the computation of the recommended reaction rate. The level observed at E x = 10.9128 (30) MeV in the Gammasphere data [22] was constrained as J π = 2 + or 6 + .…”

Section: Combining the Experimental Datamentioning

confidence: 97%

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Reevaluation of the Ne22(α,γ)Mg26 and
Adsley
¹
,
Battino
²
,
Best
³

et al. 2021
Phys. Rev. C
40
0
31
0
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Background: The competing 22 Ne(α, γ) 26 Mg and 22 Ne(α, n) 25 Mg reactions control the production of neutrons for the weak s-process in massive and AGB stars. In both systems, the ratio between the corresponding reaction rates strongly impacts the total neutron budget and strongly influences the final nucleosynthesis.Purpose: The 22 Ne(α, γ) 26 Mg and 22 Ne(α, n) 25 Mg reaction rates must be re-evaluated by using newly available information on 26 Mg given by various recent experimental studies. Evaluations of the reaction rates following the collection of new nuclear data presently show differences of up to a factor of 500 resulting in considerable uncertainty in the resulting nucleosynthesis. Methods:The new nuclear data are evaluated and, where possible, correspondence between states observed in different experiments are made. With updated spin and parity assignments, the levels which can contribute to the reaction rates are identified. The reaction rates are computed using a Monte-Carlo method which has been used for previous evaluations of the reaction rates in order to focus solely on the changes due to modified nuclear data.Results: The evaluated 22 Ne(α, γ) 26 Mg reaction rate remains substantially similar to that of Longland et al. but, including recent results from Texas A&M, the 22 Ne(α, n) 25 Mg reaction rate is lower at a range of astrophysically important temperatures. Stellar models computed with NEWTON and MESA predict decreased production of the weak branch s-process due to the decreased efficiency of 22 Ne as a neutron source. Using the new reaction rates in the MESA model results in 96 Zr/ 94 Zr and 135 Ba/ 136 Ba ratios in much better agreement with the measured ratios from presolar SiC grains. Conclusion:The 22 Ne+α reaction rates 22 Ne(α, γ) 26 Mg and 22 Ne(α.n) 25 Mg have been recalculated based on more recent nuclear data. The 22 Ne(α, γ) 26 Mg reaction rate remains substantially unchanged since the previous evaluation but the 22 Ne(α.n) 25 Mg reaction rate is substantially decreased due to updated nuclear data. This results in significant changes to the nucleosynthesis in the weak branch of the s-process.

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Sensitivity of transfer cross sections to the bound-state wave functions

Shubhchintak

Descouvemont

2020

Physics Letters B

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Constraining the 22Ne(α,γ)26Mg and 22Ne(α,n)25Mg reaction rates using sub-Coulomb α-transfer reactions

Cited by 27 publications

References 29 publications

The Study of Key Reactions Shaping the Post-Main Sequence Evolution of Massive Stars in Underground Facilities

The Study of Key Reactions Shaping the Post-Main Sequence Evolution of Massive Stars in Underground Facilities

Reevaluation of the Ne22(α,γ)Mg26 and
Adsley
¹
,
Battino
²
,
Best
³

et al. 2021
Phys. Rev. C
40
0
31
0
View full text Add to dashboard Cite

Sensitivity of transfer cross sections to the bound-state wave functions

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Constraining the 22Ne(α,γ)26Mg and 22Ne(α,n)25Mg reaction rates using sub-Coulomb α-transfer reactions

Cited by 27 publications

References 29 publications

The Study of Key Reactions Shaping the Post-Main Sequence Evolution of Massive Stars in Underground Facilities

The Study of Key Reactions Shaping the Post-Main Sequence Evolution of Massive Stars in Underground Facilities

Reevaluation of the Ne22(α,γ)Mg26 and Adsley1, Battino2, Best3 et al. 2021Phys. Rev. C400310View full textAdd to dashboardCite

Sensitivity of transfer cross sections to the bound-state wave functions

Contact Info

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Resources

About

Reevaluation of the Ne22(α,γ)Mg26 and
Adsley
¹
,
Battino
²
,
Best
³

et al. 2021
Phys. Rev. C
40
0
31
0
View full text Add to dashboard Cite