Low-energy enhancement in the γ-ray strength functions of ${}^{73,74}$Ge

Abstract

The $\gamma$-ray strength functions and level densities of ${}^{73,74}$Ge have been extracted up to the neutron separation energy S${}_n$ from particle-$\gamma$ coincidence data using the Oslo method. Moreover, the $\gamma$-ray strength function of ${}^{74}$Ge above S${}_n$ has been determined from photo-neutron measurements, hence these two experiments cover the range of E${}_{\gamma }\approx$ 1-13 MeV for ${}^{74}$Ge. The obtained data show that both ${}^{73,74}$Ge display an increase in strength at low $\gamma$ energies. The experimental $\gamma$-ray strength functions are compared with $M1$ strength functions deduced from average $B(M1)$ values calculated within the shell model for a large number of transitions. The observed low-energy enhancements in ${}^{73,74}$Ge are adopted in the calculations of the ${}^{72,73}$Ge(n,$\gamma$) cross sections, where there are no direct experimental data. Calculated reaction rates for more neutron-rich germanium isotopes are shown to be strongly dependent on the presence of the low-energy enhancement.

References in corpus (29)

• The r-process of stellar nucleosynthesis: Astrophysics and nuclear physics achievements and mysteries
• The s Process: Nuclear Physics, Stellar Models, Observations
• Skyrme-Hartree-Fock-Bogoliubov nuclear mass formulas: Crossing the 0.6 MeV threshold with microscopically deduced pairing
• Microscopic HFB+QRPA predictions of dipole strength for astrophysics applications
• Extraction of level density and gamma strength function from primary gamma spectra
• Large-scale QRPA calculation of E1-strength and its impact on the neutron capture cross section
• Analysis of possible systematic errors in the Oslo method
• Novel technique for constraining r-process (n,$\gamma$) reaction rates
• Radiative strength functions in 93-98Mo
• Large enhancement of radiative strength for soft transisitons in the quasicontinuum
• Low-energy enhancement of magnetic dipole radiation
• Impact of a low-energy enhancement in the gamma-ray strength function on the radiative neutron-capture
• Gamma-ray strength function and pygmy resonance in rare earth nuclei
• The SiRi Particle-Telescope System
• Evidence for dipole nature of the low-energy $\gamma$ enhancement in ${}^{56}$Fe
• Large low-energy $M1$ strength for ${}^{56,57}$Fe within the nuclear shell model
• Validity of the generalized Brink-Axel hypothesis in ${}^{238}$Np
• Low-energy limit of the radiative dipole strength in nuclei
• Nuclear level densities and gamma-ray strength functions in 44,45Sc
• Level densities and $\gamma$-ray strength functions in Sn isotopes
• Compilation of Giant Electric Dipole Resonances Built on Excited States
• Experimental level densities of atomic nuclei
• Microcanonical entropies and radiative strength functions of ${}^{50,51}$V
• Nuclear Level Density and Gamma-Ray Strength Function of 43Sc
• Observation of a first-order pairing phase transition in atomic nuclei
• Extraction of thermal and electromagnetic properties in 45Ti
• Fermi's golden rule applied to the gamma decay in the quasicontinuum of 46Ti
• Primary gamma-ray spectra in 44Ti of astrophysical interest
• Low-energy behavior of $E2$ strength functions

Cited by in corpus (18)

• Reference Database for Photon Strength Functions
• Novel Techniques for Constraining Neutron-Capture Rates Relevant for r-Process Heavy-Element Nucleosynthesis
• Enhanced low-energy $\gamma$-decay strength of ${}^{70}$Ni and its robustness within the shell model
• Consolidating the concept of low-energy magnetic dipole decay radiation
• Low energy magnetic radiation enhancement in the f${}_{7/2}$ shell
• Low-energy enhancement and fluctuations of $\gamma$-ray strength functions in ${}^{56,57}$Fe: test of the Brink-Axel hypothesis
• ${}^{137,138,139}$La($n$, $\gamma$) cross sections constrained with statistical decay properties of ${}^{138,139,140}$La nuclei
• Quasicontinuum $\gamma$-decay of ${}^{91,92}$Zr: benchmarking indirect ($n,\gamma$) cross section measurements for the $s$-process
• Microscopic calculations of nuclear level densities with the Lanczos method
• Nature of low-lying electric dipole resonance excitations in 74Ge
• Consistent optical potential for incident and emitted low-energy $\alpha$ particles. II. $\alpha$-emission in fast-neutron induced reactions on Zr isotopes
• A new software implementation of the Oslo method with rigorous statistical uncertainty propagation
• Role of consistent parameter sets in an assessment of the alpha-particle optical potential below the Coulomb barrier
• Nuclear Level Density and $\gamma$-ray Strength Function of ${}^{67}\mathrm{Ni}$ and the impact on the i-process
• Photoexcitation of ${}^{76}$Ge
• Inference of Parameters for Back-shifted Fermi Gas Model using Feedback Neural Network
• Comprehensive test of the Brink-Axel hypothesis in the energy region of the pygmy dipole resonance
• Nuclear level densities and $\gamma$-ray strength functions of ${}^{87}\mathrm{Kr}$ -- First application of the Oslo Method in inverse kinematics