Measurements of the48Ca(γ,n)reaction

Abstract

The48 Ca(γ,n) cross section was measured using γ-ray beams of energies between 9.5 and 15.3 MeV generated at the Triangle Universities Nuclear Laboratory (TUNL) high-intensity γ-ray source (HIγS). Prior to this experiment, no direct measurements had been made with γ-ray beams of sufficiently low energy spread to observe structure in this energy range. The cross sections were measured at thirty-four different γ-ray energies with an enriched 48 Ca target. Neutron emission is the dominant decay mechanism in the measured energy range that spans from threshold, across the previously identified M1 strength, and up the low-energy edge of the E1 giant dipole resonance (GDR). This work found B(M 1) = 6.8 ± 0.5 µ 2 N for the 10.23 MeV resonance, a value greater than previously measured. Structures in the cross section commensurate with extended random-phase approximation (ERPA) calculations have also been observed whose magnitudes are in agreement with existing data.

Properties of the first excited state of9Be derived from(γ,n)and(e,eEfros1, Neumann-Cosel2, Richter3 2014Phys. Rev. C181190View full textAdd to dashboardCite

“…The (γ,n) cross sections and thus the B(M1)↑ value deduced in Ref. [21] is almost twice that obtained in Ref. [20], while the cross sections at higher γ energies agree with those deduced from an (e,e n) experiment [22].…”

“…While we cannot provide an explanation, we note that a similar kind of discrepancy exists for the prominent neutron spin-flip M1 transition in 48 Ca whose strength plays a central role in understanding the phenomenon of quenching of the spin-isospin response [19]. It was first observed in electron scattering [20] and recently remeasured [21] with the same experimental technique as used in Ref. [4].…”

Investigation of J=1 states and their γ -decay behavior in Cr52

“…For KB3G, GPFX1A and GPFX1J the energy of the strongest 1 + state in 48 Ca is 9.3, 10.9 and 10.2 MeV, respectively, compared to the experimental value of 10.23 MeV (the KB3G strength is split between two states at 9.21 and 9.36 MeV). The calculated B(M1)↑ for the strong 1 + states is 4.7, 4.9 and 5.5 µ 2 N , respectively, compared to experimental values of 3.9(3) µ 2 N obtained with the (e,e ′ ) reaction [28,50] and 6.8(5) µ 2 N obtained with the (γ,n) reaction [51]. The latter value was recently claimed to be inconsistent with data on (p,p ′ ) reactions [52].…”

Coupling the Lorentz Integral Transform (LIT) and the Coupled Cluster (CC) Methods: A Way Towards Continuum Spectra of “Not-So-Few-Body” Systems

“…This is due to the fact that the Lorentzian kernel is a representation of the delta-function (for Γ = 0 the transform coincides with the response). While the comparison shows that the experimental centroid of the GDR is well reproduced by a calculation that neglects three-body forces, the inversion of the transform leads to a less pronounced peak with respect to experiment (see Aiming at addressing ab initio the interesting case of 48 Ca, for which recent photoabsorption measurements have been performed [15], we have calculated the LIT of its N=Z partner 40 Ca. In Fig.…”