Spectroscopic information on 24Mg and 28Si from proton capture

Endt, P.M.; Alderliesten, C.; Zijderhand, F.; Wolters, A. A.; Hees, A.

doi:10.1016/0375-9474(90)90237-g

Cited by 56 publications

(32 citation statements)

References 37 publications

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“…These branchings agree with those reported in Ref. [44] within 5 %. The obtained relative efficiency curves from this reaction were matched to the absolute efficiencies gained with calibration sources.…”

Section: Determination Of the Detector Efficienciessupporting

confidence: 82%

Investigation of the reaction74Ge(p,γ)75
Sauerwein
¹
,
Endres
²
,
Netterdon
³

et al. 2012
Phys. Rev. C
37
4
40
0
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Background: Astrophysical models studying the origin of the neutron-deficient p nuclides require the knowledge of proton capture cross sections at low energy. The production site of the p nuclei is still under discussion but a firm basis of nuclear reaction rates is required to address the astrophysical uncertainties. Data at astrophysically relevant interaction energies are scarce. Problems with the prediction of charged particle capture cross sections at low energy were found in the comparisons between previous data and calculations in the Hauser-Feshbach statistical model of compound reactions.Purpose: A measurement of 74 Ge(p,γ) 75 As at low proton energies, inside the astrophysically relevant energy region, is important in several respects. The reaction is directly important as it is a bottleneck in the reaction flow which produces the lightest p nucleus 74 Se. It is also an important addition to the data set required to test reaction-rate predictions and to allow an improvement in the global p+nucleus optical potential required in such calculations.Method: An in-beam experiment was performed, making it possible to measure in the range 2.1 ≤ Ep ≤ 3.7 MeV, which is for the most part inside the astrophysically relevant energy window. Angular distributions of the γ-ray transitions were measured with high-purity germanium detectors at eight angles relative to the beam axis. In addition to the total cross sections, partial cross sections for the direct population of twelve levels were determined. Results:The resulting cross sections were compared to Hauser-Feshbach calculations using the code SMARAGD. Only a constant renormalization factor of the calculated proton widths allowed a good reproduction of both total and partial cross sections. The accuracy of the calculation made it possible to check the spin assignment of some states in 75 As. In the case of the 1075 keV state, a double state with spins and parities of 3/2 − and 5/2 − is needed to explain the experimental partial cross sections. A change in parity from 5/2 + to 5/2 − is required for the state at 401 keV. Furthermore, in the case of 74 Ge, studying the combination of total and partial cross sections made it possible to test the γ width, which is essential in the calculation of the astrophysical 74 As(n,γ) 75 As rate. Conclusions:Between data and statistical model prediction a factor of about two was found. Nevertheless, the improved astrophysical reaction rate of 74 Ge(p,γ) (and its reverse reaction) is only 28% larger than the previous standard rate. The prediction of the 74 As(n,γ) 75 As rate (and its reverse) was confirmed, the newly calculated rate differs only by a few percent from the previous prediction. The in-beam method with high efficiency detectors proved to be a powerful tool for studies in nuclear astrophysics and nuclear structure.

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Section: Determination Of the Detector Efficienciessupporting

confidence: 82%

Investigation of the reaction74Ge(p,γ)75
Sauerwein
¹
,
Endres
²
,
Netterdon
³

et al. 2012
Phys. Rev. C
37
4
40
0
View full text Add to dashboard Cite

show abstract

“…To extend the efficiency determination to higher energies, we measured the 27 Al(p, γ) reaction using a thick aluminum target and used the relative intensities of well-known gamma-ray branches from E p = 633 and 992 [41,42]. For the latter resonance, our coin target was also used.…”

Section: E Detector Efficiencymentioning

confidence: 99%

Absolute determination of theNa22(p,γ)
Sallaska
¹
,
Wrede
²
,
Garcı́a
³

et al. 2011
Phys. Rev. C
25
5
34
0
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“…Absolute efficiency measurements were done using calibrated sources and the well-known E p = 992 keV resonance in 27 Al(p, γ) 28 Si (ωγ = 1.93 ± 0.13 eV) [14]. The absolute efficiency data were augmented with relative measurements using a 56 Co source and the E p = 1317 keV 27 Al(p, γ) 28 Si resonance [15]. The results are shown in Fig.…”

Section: Amentioning

confidence: 99%

Measurement of the reaction18O(α,n)21Ne

et al. 2013

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Background: The reaction18 O(α, n) 21 Ne is a part of the reaction chains leading to the production of 19 F and 22 Ne during He burning in low-mass and massive AGB stars, respectively. Additionally, it it has been observed as a strong background source in the measurement of other (α, n) reactions. Purpose: Previously low-energy18 O(α, n) 21 Ne cross section data have only been available in a non peer-reviewed form. An improved measurement of this reaction has been done to both clarify its astrophysical influence as well as to provide background yield data for future (α, n) experiments. Method: The18 O(α, n (0+1) ) reaction has been measured with a moderating neutron detector. In addition the (α, n1γ) channel has been measured independently by observation of the characteristic 350.7 keV γ-transition in 21 Ne. The reaction cross section at energies above Eα = 1100 keV was determined by a simultaneous R-matrix fit to both channels. The strengths of the two lowest-energy resonances at Eα = 959 keV and Eα = 1066 keV were analyzed separately using individual Breit-Wigner fits. Results:The cross section of both reaction channels,18 O(α, n0) 21 Ne and 18 O(α, n1γ) 21 Ne, was determined from the threshold energies at 851 keV and 1280 keV, respectively to 2300 keV. A new reaction rate has been deduced for the temperature range of 0.1 GK to 10 GK. A previously reported resonance at Eα = 888 keV is explained as background from the contaminant reaction 17 O(α, n) 20 Ne. Conclusions:In general, our reaction rate is slightly lower than the reaction rates in recent compilations. At temperatures below 0.2 GK the present rate is significantly lower because it could be shown that the lowest reported resonance is background from the reaction 17 O(α, n) 20 Ne that has been wrongly assigned to 18 O(α, n) 21 Ne.

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Spectroscopic information on 24Mg and 28Si from proton capture

Cited by 56 publications

References 37 publications

Investigation of the reaction74Ge(p,γ)75
Sauerwein
¹
,
Endres
²
,
Netterdon
³

et al. 2012
Phys. Rev. C
37
4
40
0
View full text Add to dashboard Cite

Investigation of the reaction74Ge(p,γ)75
Sauerwein
¹
,
Endres
²
,
Netterdon
³

et al. 2012
Phys. Rev. C
37
4
40
0
View full text Add to dashboard Cite

Absolute determination of theNa22(p,γ)
Sallaska
¹
,
Wrede
²
,
Garcı́a
³

et al. 2011
Phys. Rev. C
25
5
34
0
View full text Add to dashboard Cite

Measurement of the reaction18O(α,n)21Ne

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Spectroscopic information on 24Mg and 28Si from proton capture

Cited by 56 publications

References 37 publications

Investigation of the reaction74Ge(p,γ)75Sauerwein1, Endres2, Netterdon3 et al. 2012Phys. Rev. C374400View full textAdd to dashboardCite

Investigation of the reaction74Ge(p,γ)75Sauerwein1, Endres2, Netterdon3 et al. 2012Phys. Rev. C374400View full textAdd to dashboardCite

Absolute determination of theNa22(p,γ)Sallaska1, Wrede2, Garcı́a3 et al. 2011Phys. Rev. C255340View full textAdd to dashboardCite

Measurement of the reaction18O(α,n)21Ne

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Investigation of the reaction74Ge(p,γ)75
Sauerwein
¹
,
Endres
²
,
Netterdon
³

et al. 2012
Phys. Rev. C
37
4
40
0
View full text Add to dashboard Cite

Investigation of the reaction74Ge(p,γ)75
Sauerwein
¹
,
Endres
²
,
Netterdon
³

et al. 2012
Phys. Rev. C
37
4
40
0
View full text Add to dashboard Cite

Absolute determination of theNa22(p,γ)
Sallaska
¹
,
Wrede
²
,
Garcı́a
³

et al. 2011
Phys. Rev. C
25
5
34
0
View full text Add to dashboard Cite