<p>The nuclear ground-state features of waiting-point proton-rich nuclei with proton numbers ranging from 28 to 38 were examined using the relativistic mean-field (RMF) model with density-dependent meson-exchange (DDME2) interaction. The ground-state properties include quadrupole deformation parameter (<InlineEquation ID="IEq4"> <EquationSource Format="TEX">\(\beta _2\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>β</mi> <mn>2</mn> </msub> </math></EquationSource> </InlineEquation>), binding energy (<InlineEquation ID="IEq5"> <EquationSource Format="TEX">\(E_{b}\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>E</mi> <mi>b</mi> </msub> </math></EquationSource> </InlineEquation>), one proton (neutron) separation energy (S<InlineEquation ID="IEq6"> <EquationSource Format="TEX">\(_p\)</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mrow /> <mi>p</mi> <mrow /> </mmultiscripts> </math></EquationSource> </InlineEquation>, S<InlineEquation ID="IEq7"> <EquationSource Format="TEX">\(_n\)</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mrow /> <mi>n</mi> <mrow /> </mmultiscripts> </math></EquationSource> </InlineEquation>), two proton (neutron) separation energy (S<InlineEquation ID="IEq8"> <EquationSource Format="TEX">\(_{2p}\)</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mrow /> <mrow> <mn>2</mn> <mi>p</mi> </mrow> <mrow /> </mmultiscripts> </math></EquationSource> </InlineEquation>, S<InlineEquation ID="IEq9"> <EquationSource Format="TEX">\(_{2n}\)</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mrow /> <mrow> <mn>2</mn> <mi>n</mi> </mrow> <mrow /> </mmultiscripts> </math></EquationSource> </InlineEquation>), and neutron skin thickness (<InlineEquation ID="IEq10"> <EquationSource Format="TEX">\(R_{np}\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>R</mi> <mrow> <mi mathvariant="italic">np</mi> </mrow> </msub> </math></EquationSource> </InlineEquation>). The <InlineEquation ID="IEq11"> <EquationSource Format="TEX">\(\beta _{2}\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>β</mi> <mn>2</mn> </msub> </math></EquationSource> </InlineEquation> values, computed using the RMF model and another set adopted from the finite range droplet model, were later employed in the proton-neutron quasi particle random phase approximation (pn-QRPA) model as an input parameter for the analysis of <InlineEquation ID="IEq12"> <EquationSource Format="TEX">\(\beta\)</EquationSource> <EquationSource Format="MATHML"><math> <mi>β</mi> </math></EquationSource> </InlineEquation>-decay properties, including the Gamow-Teller (GT) strength distributions, <InlineEquation ID="IEq13"> <EquationSource Format="TEX">\(\beta\)</EquationSource> <EquationSource Format="MATHML"><math> <mi>β</mi> </math></EquationSource> </InlineEquation>-decay half-lives, and stellar <InlineEquation ID="IEq14"> <EquationSource Format="TEX">\(\beta ^{+}\)</EquationSource> <EquationSource Format="MATHML"><math> <msup> <mi>β</mi> <mo>+</mo> </msup> </math></EquationSource> </InlineEquation>/electron capture rates for proton-rich nuclei (<InlineEquation ID="IEq15"> <EquationSource Format="TEX">\(^{52}\)</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mrow /> <mrow /> <mn>52</mn> </mmultiscripts> </math></EquationSource> </InlineEquation>Ni, <InlineEquation ID="IEq16"> <EquationSource Format="TEX">\(^{56}\)</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mrow /> <mrow /> <mn>56</mn> </mmultiscripts> </math></EquationSource> </InlineEquation>Zn, <InlineEquation ID="IEq17"> <EquationSource Format="TEX">\(^{58}\)</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mrow /> <mrow /> <mn>58</mn> </mmultiscripts> </math></EquationSource> </InlineEquation>Zn, <InlineEquation ID="IEq18"> <EquationSource Format="TEX">\(^{61}\)</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mrow /> <mrow /> <mn>61</mn> </mmultiscripts> </math></EquationSource> </InlineEquation>Ga, <InlineEquation ID="IEq19"> <EquationSource Format="TEX">\(^{62}\)</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mrow /> <mrow /> <mn>62</mn> </mmultiscripts> </math></EquationSource> </InlineEquation>Ge, <InlineEquation ID="IEq20"> <EquationSource Format="TEX">\(^{70}\)</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mrow /> <mrow /> <mn>70</mn> </mmultiscripts> </math></EquationSource> </InlineEquation>Kr, and <InlineEquation ID="IEq21"> <EquationSource Format="TEX">\(^{76}\)</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mrow /> <mrow /> <mn>76</mn> </mmultiscripts> </math></EquationSource> </InlineEquation>Sr). The calculated stellar rates changed marginally with a change in the deformation parameter. For core density <InlineEquation ID="IEq22"> <EquationSource Format="TEX">\(10^{7}\)</EquationSource> <EquationSource Format="MATHML"><math> <msup> <mn>10</mn> <mn>7</mn> </msup> </math></EquationSource> </InlineEquation> g/cm<InlineEquation ID="IEq23"> <EquationSource Format="TEX">\(^3\)</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mrow /> <mrow /> <mn>3</mn> </mmultiscripts> </math></EquationSource> </InlineEquation> (<InlineEquation ID="IEq24"> <EquationSource Format="TEX">\(10^{11}\)</EquationSource> <EquationSource Format="MATHML"><math> <msup> <mn>10</mn> <mn>11</mn> </msup> </math></EquationSource> </InlineEquation> g/cm<InlineEquation ID="IEq25"> <EquationSource Format="TEX">\(^3\)</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mrow /> <mrow /> <mn>3</mn> </mmultiscripts> </math></EquationSource> </InlineEquation>), the computed sum of <InlineEquation ID="IEq26"> <EquationSource Format="TEX">\(\beta ^+\)</EquationSource> <EquationSource Format="MATHML"><math> <msup> <mi>β</mi> <mo>+</mo> </msup> </math></EquationSource> </InlineEquation> and electron capture rates increases up to 3 (1) orders of magnitude as the core temperature rises from 0.01 to 30 GK. Additionally, the present calculated rates were compared with earlier computations for nuclei <InlineEquation ID="IEq27"> <EquationSource Format="TEX">\(^{70}\)</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mrow /> <mrow /> <mn>70</mn> </mmultiscripts> </math></EquationSource> </InlineEquation>Kr and <InlineEquation ID="IEq28"> <EquationSource Format="TEX">\(^{76}\)</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mrow /> <mrow /> <mn>76</mn> </mmultiscripts> </math></EquationSource> </InlineEquation>Sr that were carried out using the independent particle model (IPM). The computed pn-QRPA (FRDM) rates are up to a factor of 5 larger than the IPM results in high temperature-density environments. The results of the present investigation may prove useful in simulating realistic nucleosynthesis models.</p>

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Impact of nuclear deformation on β-decay properties of proton-rich waiting point nuclei

  • Wajeeha Khalid,
  • Abdul Kabir,
  • Jameel-Un Nabi,
  • Khush Bakhat

摘要

The nuclear ground-state features of waiting-point proton-rich nuclei with proton numbers ranging from 28 to 38 were examined using the relativistic mean-field (RMF) model with density-dependent meson-exchange (DDME2) interaction. The ground-state properties include quadrupole deformation parameter ( \(\beta _2\) β 2 ), binding energy ( \(E_{b}\) E b ), one proton (neutron) separation energy (S \(_p\) p , S \(_n\) n ), two proton (neutron) separation energy (S \(_{2p}\) 2 p , S \(_{2n}\) 2 n ), and neutron skin thickness ( \(R_{np}\) R np ). The \(\beta _{2}\) β 2 values, computed using the RMF model and another set adopted from the finite range droplet model, were later employed in the proton-neutron quasi particle random phase approximation (pn-QRPA) model as an input parameter for the analysis of \(\beta\) β -decay properties, including the Gamow-Teller (GT) strength distributions, \(\beta\) β -decay half-lives, and stellar \(\beta ^{+}\) β + /electron capture rates for proton-rich nuclei ( \(^{52}\) 52 Ni, \(^{56}\) 56 Zn, \(^{58}\) 58 Zn, \(^{61}\) 61 Ga, \(^{62}\) 62 Ge, \(^{70}\) 70 Kr, and \(^{76}\) 76 Sr). The calculated stellar rates changed marginally with a change in the deformation parameter. For core density \(10^{7}\) 10 7 g/cm \(^3\) 3 ( \(10^{11}\) 10 11 g/cm \(^3\) 3 ), the computed sum of \(\beta ^+\) β + and electron capture rates increases up to 3 (1) orders of magnitude as the core temperature rises from 0.01 to 30 GK. Additionally, the present calculated rates were compared with earlier computations for nuclei \(^{70}\) 70 Kr and \(^{76}\) 76 Sr that were carried out using the independent particle model (IPM). The computed pn-QRPA (FRDM) rates are up to a factor of 5 larger than the IPM results in high temperature-density environments. The results of the present investigation may prove useful in simulating realistic nucleosynthesis models.