Investigation of α-induced reactions on the p nucleus

Netterdon, L.; Demetriou, P.; Endres, J.; Giesen, U.; Kiss, G.; Sauerwein, A.; Szücs, T.; Zell, K. O.; Zilges, A.

doi:10.1016/j.nuclphysa.2013.08.002

Cited by 43 publications

(67 citation statements)

References 55 publications

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“…It was found that the experimental cross sections for both reactions are smaller than the ones predicted by the reaction model which has been used in previous γ-process studies. This is in line with the findings of previous (α,γ) and (α,n) experiments on other p nuclei, which also showed smaller cross sections than predicted (see [15,20,23] and references in [32]). …”

Section: Conclusion and Summarysupporting

confidence: 92%

“…An experimental check of the theoretical cross sections is therefore important to examine one possible reason of the deficiencies. This need triggered huge experimental work in the last decade on studying reactions relevant for the γ process (see the references in the review paper [6] and some of the most recent studies [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31]). …”

Section: Introductionmentioning

confidence: 99%

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Experimental study of the astrophysicalγ-process reactionXe124(α,γ)Ba
Halász
¹
,
Somorjai
²
,
Gyürky
³

et al. 2016
Phys. Rev. C
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0
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Background: The synthesis of heavy, proton rich isotopes in the astrophysical γ process proceeds through photodisintegration reactions. For the improved understanding of the process, the rates of the involved nuclear reactions must be known. The reaction 128 Ba(γ,α) 124 Xe was found to affect the abundance of the p nucleus 124 Xe in previous rate variation studies.Purpose: Since the stellar rate for this reaction cannot be determined by a measurement directly, the aim of the present work was to measure the cross section of the inverse 124 Xe(α,γ) 128 Ba reaction and to compare the results with statistical model predictions used in astrophysical networks. Modified nuclear input can then be used to provide an improved stellar reaction rate. Of great importance is the fact that data below the (α,n) threshold was obtained. Studying simultaneously the 124 Xe(α,n) 127 Ba reaction channel at higher energy allowed to further identify the source of a discrepancy between data and prediction.Method: The 124 Xe(α,γ) 128 Ba and 124 Xe(α,n) 127 Ba cross sections were measured with the activation method using a thin window 124 Xe gas cell and an α beam from a cyclotron accelerator. The studied energy range was between Eα = 11 and 15 MeV close above the astrophysically relevant energy range. Results:The obtained cross sections are compared with Hauser-Feshbach statistical model calculations. The experimental cross sections are smaller than standard predictions previously used in astrophysical calculations. As dominating source of the difference, the theoretical α width was identified. The experimental data suggest an α width lower by at least a factor of 0.125 in the astrophysically important energy range.Conclusions: An upper limit for the 128 Ba(γ,α) 124 Xe stellar rate was inferred from our measurement. The impact of this rate and lower rates was studied in two different models for core-collapse supernova explosions of 25 M⊙ stars. A significant contribution to the 124 Xe abundance via this reaction path would only be possible when the rate was increased above the previous standard value. Since the experimental data rule this out, they also demonstrate the closure of this production path.

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Section: Conclusion and Summarysupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Experimental study of the astrophysicalγ-process reactionXe124(α,γ)Ba
Halász
¹
,
Somorjai
²
,
Gyürky
³

et al. 2016
Phys. Rev. C
Self Cite
16
0
17
0
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“…The more recent (α, x) reaction data concern mainly heavier target nuclei and incident energies well below B [4][5][6][7][8][9][10][11][12][13][14] (Fig. 1).…”

Section: (α X) Reaction Data Analysismentioning

confidence: 99%

“…Thus, while the use of this potential led to description of some new data almost as well as local potentials [3-7, 9, 17] or showing the best agreement of global potentials [1,2,[18][19][20], underestimation of newer data [8,[10][11][12][13][14] was also found. Hence a revision of this OMP [16] became desirable and forms the object of the present work.…”

Section: Introductionmentioning

confidence: 99%

Further explorations of theα-particle optical model potential at low energies for the mass rangeA≈45–209

2014

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The recent high-precision measurements of α-particle induced reaction data below the Coulomb barrier (B) make possible the understanding of limits and possible improvement of a previous optical model potential (OMP) for α-particles on nuclei within the mass number range 45≤A≤209 [M. Avrigeanu et al., Phys. Rev. C 82, 014606 (2010)]. An updated version of this potential is given in the present work concerning mainly an increased surface imaginary potential depth well below B for A>130. Moreover, underestimation of reaction cross sections for well-deformed nuclei is removed by using ∼7% larger radius for the surface imaginary part of this spherical OMP. Improved input parameters based on recent independent data, particularly γ-ray strength functions, but no empirical rescaling factor of the γ and/or neutron widths have been involved within statistical model calculation of the corresponding (α, x) reaction cross sections.

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“…Besides the activation technique, which has been widely used for the determination of total cross sections before [12][13][14][15][16][17], also the in-beam technique with high-purity germanium (HPGe) detectors [18][19][20][21] and the 4π -summing method [22][23][24] is available. In order to systematically check the validity of the HF calculations, experimental data over a wide mass range is highly desired.…”

Section: Introductionmentioning

confidence: 99%

Cross-section measurement of theBa130(p,γ)La131reaction for
Netterdon
¹
,
Endres
²
,
Kiss
³

et al. 2014
Phys. Rev. C
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Background: Deviations between experimental data of charged-particle-induced reactions and calculations within the statistical model are frequently found. An extended data base is needed to address the uncertainties regarding the nuclear-physics input parameters in order to understand the nucleosynthesis of the neutron-deficient p nuclei. Purpose: A measurement of total cross-section values of the 130 Ba(p,γ ) 131 La reaction at low proton energies allows a stringent test of statistical model predictions with different proton+nucleus optical model potentials. Since no experimental data are available for proton-capture reactions in this mass region around A ≈ 130, this measurement can be an important input to test the global applicability of proton+nucleus optical model potentials. Method: The total reaction cross-section values were measured by means of the activation method. After the irradiation with protons, the reaction yield was determined by use of γ -ray spectroscopy using two clover-type high-purity germanium detectors. In total, cross-section values for eight different proton energies could be determined in the energy range between 3.6 MeV E p 5.0 MeV, thus, inside the astrophysically relevant energy region. Results: The measured cross-section values were compared to Hauser-Feshbach calculations using the statistical model codes TALYS and SMARAGD with different proton+nucleus optical model potentials. With the semimicroscopic JLM proton+nucleus optical model potential used in the SMARAGD code, the absolute cross-section values are reproduced well, but the energy dependence is too steep at the lowest energies. The best description is given by a TALYS calculation using the semimicroscopic Bauge proton+nucleus optical model potential using a constant renormalization factor. Conclusions: The statistical model calculation using the Bauge semimicroscopic proton+nucleus optical model potential deviates by a constant factor of 2.1 from the experimental data. Using this model, an experimentally supported stellar reaction rate for proton capture on the p nucleus 130 Ba was calculated. At astrophysical temperatures, an increase in the stellar reaction rate of 68% compared to rates obtained from the widely used NON-SMOKER code is found. This measurement extends the scarce experimental data base for charged-particle-induced reactions, which can be helpful to derive a more globally applicable proton+nucleus optical model potential.

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Investigation of α-induced reactions on the p nucleus

Cited by 43 publications

References 55 publications

Experimental study of the astrophysicalγ-process reactionXe124(α,γ)Ba
Halász
¹
,
Somorjai
²
,
Gyürky
³

et al. 2016
Phys. Rev. C
Self Cite
16
0
17
0
View full text Add to dashboard Cite

Experimental study of the astrophysicalγ-process reactionXe124(α,γ)Ba
Halász
¹
,
Somorjai
²
,
Gyürky
³

et al. 2016
Phys. Rev. C
Self Cite
16
0
17
0
View full text Add to dashboard Cite

Further explorations of theα-particle optical model potential at low energies for the mass rangeA≈45–209

Cross-section measurement of theBa130(p,γ)La131reaction for
Netterdon
¹
,
Endres
²
,
Kiss
³

et al. 2014
Phys. Rev. C
Self Cite
25
0
26
0
View full text Add to dashboard Cite

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Investigation of α-induced reactions on the p nucleus

Cited by 43 publications

References 55 publications

Experimental study of the astrophysicalγ-process reactionXe124(α,γ)BaHalász1, Somorjai2, Gyürky3 et al. 2016Phys. Rev. CSelf Cite160170View full textAdd to dashboardCite

Experimental study of the astrophysicalγ-process reactionXe124(α,γ)BaHalász1, Somorjai2, Gyürky3 et al. 2016Phys. Rev. CSelf Cite160170View full textAdd to dashboardCite

Further explorations of theα-particle optical model potential at low energies for the mass rangeA≈45–209

Cross-section measurement of theBa130(p,γ)La131reaction forNetterdon1, Endres2, Kiss3 et al. 2014Phys. Rev. CSelf Cite250260View full textAdd to dashboardCite

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Experimental study of the astrophysicalγ-process reactionXe124(α,γ)Ba
Halász
¹
,
Somorjai
²
,
Gyürky
³

et al. 2016
Phys. Rev. C
Self Cite
16
0
17
0
View full text Add to dashboard Cite

Experimental study of the astrophysicalγ-process reactionXe124(α,γ)Ba
Halász
¹
,
Somorjai
²
,
Gyürky
³

et al. 2016
Phys. Rev. C
Self Cite
16
0
17
0
View full text Add to dashboard Cite

Cross-section measurement of theBa130(p,γ)La131reaction for
Netterdon
¹
,
Endres
²
,
Kiss
³

et al. 2014
Phys. Rev. C
Self Cite
25
0
26
0
View full text Add to dashboard Cite