Quantum numbers of26Al levels above 6 MeV excitation energy

Brenneisen, J.; Grathwohl, Dominik; Ehrhard, B.; Endt, P.M.; Fischer, S. M.; Lickert, M.; Ott, R. J.; Röpke, H.; Schmälzlin, J.; Siedle, P.; Wildenthal, B. H.

doi:10.1007/bf02769530

Cited by 6 publications

(13 citation statements)

References 16 publications

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“…Their influence is only felt in the spectrum of I π = 0 + , T = 0 levels above 9.5 MeV. Apart from this fact shell-model calculations within the untruncated s-d basis space are able to reproduce the complete spectrum of positiveparity states in 32 S with an rms deviation of 200 keV, which is the accuracy previously observed [3][4][5][6][7][8][9] in the A = 21 − 28 region. The experimental-theoretical agreement is not confined to levels on or near the yrast line, which have in part been used to adjust [2] the matrix elements of the residual interaction.…”

Section: Discussionmentioning

confidence: 59%

“…The latter one is introduced with the goal of obtaining a universal Hamiltonian which can describe all nuclides of the shell at a comparable level of accuracy. Extensive tests of model predictions have been performed for a series of nuclides between A = 21 and A = 28 [3][4][5][6][7][8][9] yielding excellent agreement with experimental data over unprecedentedly large ranges of excitation energy. The favourable experimental situation which is now achieved for 32 S allows an extension of our tests to a nucleus in the upper half of the s-d shell where new matrix elements of the residual interaction come into play.…”

Section: Introductionmentioning

confidence: 84%

“…The calculations of these quantities were performed using freenucleon g-factors and effective charges of 1.35 e p for the proton and 0.35 e p for the neutron, as was the case in preceding studies [3][4][5][6][7][8][9] of the lighter s-d shell nuclei. The γ-decay of T = 0 states is essentially due to isoscalar E2 transitions.…”

Section: Discussionmentioning

confidence: 99%

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The structure of 32S II. Shell model interpretation

Brenneisen

Erhardt

Glatz

et al. 1997

Z Phys A - Particles and Fields

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The properties of positive-parity states in 32 S are compared to predictions of shell model calculations within the complete s-d basis space using the universal s-d shell Hamiltonian. The experimental T = O spectrum is reproduced to excitation energies between 10 and 11.7 MeV, depending on the level spins. The T = 1 spectrum is known and reproduced for the first five 5 MeV in excitation in general and for the first 8 MeV in the case of I π = 1 + states. Altogether the excitation energies of 80 positive-parity states are reproduced with a rms deviation of 200 keV. A calculation of radiative widths and branching ratios for γ-decay which uses effective charges and free-nucleon g-factors yields good general agreement with experiment. The need for effective g-factors is felt only in the rare cases of transitions which are governed by the isovector d 3/2 → d 5/2 M1 matrix element. The spectrum of negative parity, T = 1 states is understood in terms of the weakcoupling model while that of the T = 0 states is comprised of octupole-quadrupole phonon multiplets. Positive-parity states from outside the s-d configuration are first observed between 9.5 and 10.5 MeV excitation energy.

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Section: Discussionmentioning

confidence: 59%

Section: Introductionmentioning

confidence: 84%

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The structure of 32S II. Shell model interpretation

Brenneisen

Erhardt

Glatz

et al. 1997

Z Phys A - Particles and Fields

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“…The energy of the particle beam impinging on the target was measured by scanning the Ep -3674.4 keV resonance of the 27A1 (p,y) reaction [30]. The proton energy was changed in small steps of 0.5 to 1 keV.…”

Section: B Determination Of A-particle Energymentioning

confidence: 99%

Total and partial cross sections of theSn112(α,γ)Te116
Netterdon
¹
,
Mayer
²
,
Scholz
³

et al. 2015
Phys. Rev. C
31
0
31
0
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Background:The nucleosynthesis of the neutron-deficient p nuclei remains an open question in nuclear astrophysics. Beside uncertainties on the astrophysical side, the nuclear-physics input parameters entering Hauser-Feshbach calculations for the nucleosynthesis of the p nuclei must be put on a firm basis. Purpose: An extended database of experimental data is needed to address uncertainties of the nuclear-physics input parameters for Hauser-Feshbach calculations. Especially a-(-nucleus optical model potentials at low energies are not well known. The in-beam technique with an array of high-purity germanium (HPGe) detectors was successfully applied to the measurement of absolute cross sections of an (a,y ) reaction on a heavy nucleus at sub-Coulomb energies. Method: The total and partial cross-section values were measured by means of in-beam y -ray spectroscopy. For this purpose, the absolute reaction yield was measured using the HPGe detector array HORUS at the FN tandem accelerator at the University of Cologne. Total and partial cross sections were measured at four different a-particle energies from Ea -10.5 MeV to Ea = 12 MeV. Results: The measured total cross-section values are in excellent agreement with previous results obtained with the activation technique, which proves the validity of the applied method. With the present measurement, the discrepancy between two older data sets is removed. The experimental data was compared to Hauser-Feshbach calculations using the nuclear reaction code TALYS. With a modification of the semi-microscopic a + nucleus optical model potential OMP 3, the measured cross-section values are reproduced well. Moreover, partial cross sections could be measured for the first time for an (a , y ) reaction. Conclusions: A modified version of the semimicroscopic a + nucleus optical model potential OMP3, as well as modified proton and y widths, are needed in order to obtain a good agreement between experimental data and theory. It is found that a model using a local modification of the nuclear-physics input parameters simultaneously reproduces total cross sections of the ll2Sn(a,y) and ll2Sn(a,p) reactions. The measurement of partial cross sections turns out to be very important in this case in order to apply the correct y-ray strength function in the Hauser-Feshbach calculations. The model also reproduces cross-section values of a-induced reactions on l06Cd, as well as of (a.n) reactions on 1 l5 ll6Sn, hinting at a more global character of the obtained nuclear-physics input.

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“…The energy of the proton beam impinging on the target was determined by scanning the E p = 3674.4 keV resonance of the 27 Al(p,γ ) reaction [28]. From the sharp rising edge of the obtained resonance yield curve, a spread in proton energy of ±4 keV as well as a constant offset of 29 keV with respect to the literature value of the resonance was found.…”

Section: B Experimental Setupmentioning

confidence: 99%

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

et al. 2014
Phys. Rev. C
26
0
26
0
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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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Quantum numbers of26Al levels above 6 MeV excitation energy

Cited by 6 publications

References 16 publications

The structure of 32S II. Shell model interpretation

The structure of 32S II. Shell model interpretation

Total and partial cross sections of theSn112(α,γ)Te116
Netterdon
¹
,
Mayer
²
,
Scholz
³

et al. 2015
Phys. Rev. C
31
0
31
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
26
0
26
0
View full text Add to dashboard Cite

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Quantum numbers of26Al levels above 6 MeV excitation energy

Cited by 6 publications

References 16 publications

The structure of 32S II. Shell model interpretation

The structure of 32S II. Shell model interpretation

Total and partial cross sections of theSn112(α,γ)Te116Netterdon1, Mayer2, Scholz3 et al. 2015Phys. Rev. C310310View full textAdd to dashboardCite

Cross-section measurement of theBa130(p,γ)La131reaction forNetterdon1, Endres2, Kiss3 et al. 2014Phys. Rev. C260260View full textAdd to dashboardCite

Contact Info

Product

Resources

About

Total and partial cross sections of theSn112(α,γ)Te116
Netterdon
¹
,
Mayer
²
,
Scholz
³

et al. 2015
Phys. Rev. C
31
0
31
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
26
0
26
0
View full text Add to dashboard Cite