Proton capture reaction cross section measurements on 
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi>Er</mml:mi><mml:mprescripts /><mml:none /><mml:mn>162</mml:mn></mml:mmultiscripts></mml:math>
 as a probe of statistical model calculations

“…4, we compare the results obtained for all possible values of the f v and f w factors for four cases representing a broad mass range, namely 47 Ti, 65 Cu, 87 Sr, 162 Er. [26] and [40], respectively, compared to model calculations using different values of fv for the JLM/B pOMP. For 87 Sr, more than one value of fv factor describes the experimental data well while for 162 Er only fv = 1.4 can reproduce the data.…”

Section: Parameter Searchmentioning

confidence: 99%

Systematics of semi-microscopic proton-nucleus optical potential at low energies relevant to nuclear astrophysics

Vagena,

Axiotis,

Dimitriou

2021

Preprint

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Background: Astrophysical models studying the origin of the neutron-deficient p nuclides require knowledge of the reaction rates of neutron, proton and α-proton photodisintegrations of pre-existing neutron-rich s-and r-nuclei and of proton capture reaction rates. Since experimental data at astrophysically relevant interaction energies are limited, reaction rate calculations rely on the predictions of the Hauser-Feshbach (HF) theory. The HF theory requires nuclear physics input such as masses, level densities, γ-ray strength functions and proton-nucleus optical potentials (OMP) describing the average interaction between the p and the nucleus. The proton OMP plays an important role in the description of proton photodisintegrations and radiative capture reactions at low energies relevant to the p-process nucleosynthesis.Purpose: The scope of this work is to improve a global semi-microscopic optical potential for protons at low energies relevant to the p-process nucleosynthesis. This is achieved by adjusting the normalization parameters of the OMP to all available radiative proton-capture cross sections measured at energies of astrophysical interest. By establishing the systematic behaviour of these parameters, one expects to enhance the predictive power of the proton OMP when expanding to mass regions where no data exists.Method: The Hauser-Feshbach calculations were obtained using the TALYS nuclear reaction code. The normalization parameters for the real and imaginary central potentials (λV and λW ) were adjusted to fit the proton data in the energy range where the cross-section calculations are independent of other input parameters, i.e. neutron optical potential, nuclear level density and γray strength function. As a consequence, the optimization of the proton OMP was done at energies below the opening of the (p, n) reaction threshold. The goodness of the fit is based on the chi-square method as well as on visual comparisons.Results: The results show that the normalization parameter λV of the real part of the proton OMP has a strong mass dependence that can be described by a second degree polynomial function for A ≤100 (low mass range) and an exponential increase for 100 < A < 162 (intermediate mass range). Though variations of the normalization parameter of the imaginary part λW have a smaller effect on the calculations, a global increase by 50% improves the results for certain nuclei without affecting the rest of the cases.Conclusions: The resulting adjustment functions were obtained by fitting all suitable proton cross-section data at low energies and can be used with reasonable confidence to generate the global semi-microscopic proton optical potential for nuclei in the medium to heavy mass region. For better statistics, more low-energy proton-capture cross section data are needed for heavier nuclei with mass A > 100.

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“…Other astrophysical process for which the activation method is extensively used is the γ-process [12]. The dominant part of the experimental cross section database [41] relevant to the γ-process is collected from activation experiments [17,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80]. In the case of neutron induced reactions, the ones involved in the sprocess network are often studied by the activation method [7].…”

Section: Number Of Alive Radioactive Nuclei Time T Irrad T C T Wmentioning

confidence: 99%

The activation method for cross section measurements in nuclear astrophysics

et al. 2019

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The primary aim of experimental nuclear astrophysics is to determine the rates of nuclear reactions taking place in stars in various astrophysical conditions. These reaction rates are important ingredient for understanding the elemental abundance distribution in our solar system and the galaxy. The reaction rates are determined from the cross sections which need to be measured at energies as close to the astrophysically relevant ones as possible. In many cases the final nucleus of an astrophysically important reaction is radioactive which allows the cross section to be determined based on the off-line measurement of the number of produced isotopes. In general, this technique is referred to as the activation method, which often has substantial advantages over in-beam particle-or γ-detection measurements. In this paper the activation method is reviewed from the viewpoint of nuclear astrophysics. Important aspects of the activation method are given through several reaction studies for charged particle, neutron and γ-induced reactions. Various techniques for the measurement of the produced activity are detailed. As a special case of activation, the technique of Accelerator Mass Spectrometry in cross section measurements is also reviewed. PACS. 26.20.-f Hydrostatic stellar nucleosynthesis -26.30.-k Nucleosynthesis in novae, supernovae, and other explosive environments -24.10.-i Nuclear reaction models and methodsContents

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Proton capture reaction cross section measurements on Er162 as a probe of statistical model calculations

Cited by 8 publications

References 55 publications

The origin of low-abundance neutron-deficient stable isotopes and the relevant cross section measurements

The origin of low-abundance neutron-deficient stable isotopes and the relevant cross section measurements

Systematics of semi-microscopic proton-nucleus optical potential at low energies relevant to nuclear astrophysics

The activation method for cross section measurements in nuclear astrophysics

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