First observation of low-energy γ-ray enhancement in the rare-earth region

Abstract

The γ-ray strength function and level density in the quasi-continuum of 151,153Sm have been measured using BGO shielded Ge clover detectors of the STARLiTeR system. The Compton shields allow for an extraction of the γ strength down to unprecedentedly low γ energies of about 500 keV. For the first time an enhanced low- energy γ-ray strength has been observed in the rare-earth region. In addition, for the first time both the upbend and the well known scissors resonance have been observed simultaneously for the same nucleus. Hauser-Feshbach calculations show that this strength enhancement at low γ energies could have an impact of 2-3 orders of magnitude on the (n,γ) reaction rates for the r-process nucleosynthesis.

References in corpus (21)

• Skyrme-Hartree-Fock-Bogoliubov nuclear mass formulas: Crossing the 0.6 MeV threshold with microscopically deduced pairing
• Magnetic dipole excitations in nuclei: elementary modes of nucleonic motion
• Microscopic HFB+QRPA predictions of dipole strength for astrophysics applications
• Extraction of level density and gamma strength function from primary gamma spectra
• Further explorations of Skyrme-Hartree-Fock-Bogoliubov mass formulas. II: Role of the effective mass
• Critical temperature for quenching of pair correlations
• Radiative strength functions in 93-98Mo
• Large enhancement of radiative strength for soft transisitons in the quasicontinuum
• Low-energy enhancement of magnetic dipole radiation
• Gamma-ray strength function and pygmy resonance in rare earth nuclei
• 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
• Thermal properties and radiative strengths in 160,161,162Dy
• Scissors resonance in the quasi-continuum of Th, Pa and U isotopes
• Validity of the generalized Brink-Axel hypothesis in ${}^{238}$Np
• Observation of large scissors resonance strength in actinides
• Low-energy limit of the radiative dipole strength in nuclei
• Level densities and $\gamma$-ray strength functions in ${}^{170,171,172}$Yb
• Radiative strength functions in 163,164Dy
• Observation of a first-order pairing phase transition in atomic nuclei
• Low-energy magnetic radiation: deviations from GOE

Cited by in corpus (20)

• Novel Techniques for Constraining Neutron-Capture Rates Relevant for r-Process Heavy-Element Nucleosynthesis
• Understanding the Low-Energy Enhancement of the $\gamma$-ray Strength Function of ${}^{56}$Fe
• Experimentally constrained ($p,\gamma$)${}^{89}$Y and ($n,\gamma$)${}^{89}$Y reaction rates relevant to the $p$-process 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
• Nuclear Dipole Response in the Finite-Temperature Relativistic Time Blocking Approximation
• Nuclear level densities and gamma-ray strength functions in samarium isotopes
• Statistical properties of the well deformed ${}^{153,155}$Sm nuclei and the scissors resonance
• A new software implementation of the Oslo method with rigorous statistical uncertainty propagation
• Evolution of low-lying M1 modes in germanium isotopes
• Low-energy enhancement in the magnetic dipole $\gamma$-ray strength functions of heavy nuclei
• Photoexcitation of ${}^{76}$Ge
• Radiative-capture cross sections for the ${}^{139}$La($n,\gamma$) reactionusing thermal neutrons and structural properties of ${}^{140}$La
• Power-law intensity distribution in $\gamma$-decay cascades -- Nuclear Structure as a Scale-Free Random Network
• Constraining the Synthesis of the Lightest p Nucleus 74Se
• The beta-Oslo method: experimentally constrained ($n,\gamma$) reaction rates relevant to the $r$-process
• Nuclear level densities and $\gamma$-ray strength functions of ${}^{87}\mathrm{Kr}$ -- First application of the Oslo Method in inverse kinematics