학술논문
Photo-response of the N=Z24 nucleus N=Z24Mg
Document Type
Original Paper
Author
Deary, J.; Scheck, M.; Schwengner, R.; O’Donnell, D.; Bemmerer, D.; Beyer, R.; Hensel, Th.; Junghans, A. R.; Kögler, T.; Müller, S. E.; Römer, K.; Schmidt, K.; Turkat, S.; Urlaß, S.; Wagner, A.; Bowry, M.; Adsley, P.; Agar, O.; Chapman, R.; Crespi, F. C. L.; Doherty, D. T.; Gayer, U. Friman; Herzberg, R.-D.; Isaak, J.; Janssens, R. V. F.; Kröll, T.; Löher, B.; Nara Singh, B. S.; von Neumann-Cosel, P.; Pellegri, L.; Peters, E. E.; Rainovski, G.; Savran, D.; Smith, J. F.; Spieker, M.; Thirolf, P. G.; Triambak, S.; Tornow, W.; Venhart, M.; Wiedeking, M.; Wieland, O.; Yates, S. W.; Zilges, A.
Source
The European Physical Journal A: Hadrons and Nuclei. 59(9)
Subject
Language
English
ISSN
1434-601X
Abstract
The electric E1 and magnetic M1 dipole responses of the N=Z2424γ,γ′Jπ=1-Jπ=1+Jπ=2+24γγB(M1)↑=2.7(3)μN2N=Z∑B(E1)↑≤0.61×10-322B(Π1,1iπ→21+)/B(Π1,1iπ→0gs+)24ρ2(E0,02+→0gs+)B(M1,1+→02+)/B(M1,1+→0gs+)1+Δβ2202+ nucleus N=Z2424γ,γ′Jπ=1-Jπ=1+Jπ=2+24γγB(M1)↑=2.7(3)μN2N=Z∑B(E1)↑≤0.61×10-322B(Π1,1iπ→21+)/B(Π1,1iπ→0gs+)24ρ2(E0,02+→0gs+)B(M1,1+→02+)/B(M1,1+→0gs+)1+Δβ2202+Mg were investigated in an inelastic photon scattering experiment. The 13.0 MeV electrons, which were used to produce the unpolarised bremsstrahlung in the entrance channel of the N=Z2424γ,γ′Jπ=1-Jπ=1+Jπ=2+24γγB(M1)↑=2.7(3)μN2N=Z∑B(E1)↑≤0.61×10-322B(Π1,1iπ→21+)/B(Π1,1iπ→0gs+)24ρ2(E0,02+→0gs+)B(M1,1+→02+)/B(M1,1+→0gs+)1+Δβ2202+Mg(N=Z2424γ,γ′Jπ=1-Jπ=1+Jπ=2+24γγB(M1)↑=2.7(3)μN2N=Z∑B(E1)↑≤0.61×10-322B(Π1,1iπ→21+)/B(Π1,1iπ→0gs+)24ρ2(E0,02+→0gs+)B(M1,1+→02+)/B(M1,1+→0gs+)1+Δβ2202+) reaction, were delivered by the ELBE accelerator of the Helmholtz-Zentrum Dresden-Rossendorf. The collimated bremsstrahlung photons excited one N=Z2424γ,γ′Jπ=1-Jπ=1+Jπ=2+24γγB(M1)↑=2.7(3)μN2N=Z∑B(E1)↑≤0.61×10-322B(Π1,1iπ→21+)/B(Π1,1iπ→0gs+)24ρ2(E0,02+→0gs+)B(M1,1+→02+)/B(M1,1+→0gs+)1+Δβ2202+, four N=Z2424γ,γ′Jπ=1-Jπ=1+Jπ=2+24γγB(M1)↑=2.7(3)μN2N=Z∑B(E1)↑≤0.61×10-322B(Π1,1iπ→21+)/B(Π1,1iπ→0gs+)24ρ2(E0,02+→0gs+)B(M1,1+→02+)/B(M1,1+→0gs+)1+Δβ2202+, and six N=Z2424γ,γ′Jπ=1-Jπ=1+Jπ=2+24γγB(M1)↑=2.7(3)μN2N=Z∑B(E1)↑≤0.61×10-322B(Π1,1iπ→21+)/B(Π1,1iπ→0gs+)24ρ2(E0,02+→0gs+)B(M1,1+→02+)/B(M1,1+→0gs+)1+Δβ2202+ states in N=Z2424γ,γ′Jπ=1-Jπ=1+Jπ=2+24γγB(M1)↑=2.7(3)μN2N=Z∑B(E1)↑≤0.61×10-322B(Π1,1iπ→21+)/B(Π1,1iπ→0gs+)24ρ2(E0,02+→0gs+)B(M1,1+→02+)/B(M1,1+→0gs+)1+Δβ2202+Mg. De-excitation N=Z2424γ,γ′Jπ=1-Jπ=1+Jπ=2+24γγB(M1)↑=2.7(3)μN2N=Z∑B(E1)↑≤0.61×10-322B(Π1,1iπ→21+)/B(Π1,1iπ→0gs+)24ρ2(E0,02+→0gs+)B(M1,1+→02+)/B(M1,1+→0gs+)1+Δβ2202+ rays were detected using the four high-purity germanium detectors of the N=Z2424γ,γ′Jπ=1-Jπ=1+Jπ=2+24γγB(M1)↑=2.7(3)μN2N=Z∑B(E1)↑≤0.61×10-322B(Π1,1iπ→21+)/B(Π1,1iπ→0gs+)24ρ2(E0,02+→0gs+)B(M1,1+→02+)/B(M1,1+→0gs+)1+Δβ2202+ELBE setup, which is dedicated to nuclear resonance fluorescence experiments. In the energy region up to 13.0 MeV a total N=Z2424γ,γ′Jπ=1-Jπ=1+Jπ=2+24γγB(M1)↑=2.7(3)μN2N=Z∑B(E1)↑≤0.61×10-322B(Π1,1iπ→21+)/B(Π1,1iπ→0gs+)24ρ2(E0,02+→0gs+)B(M1,1+→02+)/B(M1,1+→0gs+)1+Δβ2202+ is observed, but this N=Z2424γ,γ′Jπ=1-Jπ=1+Jπ=2+24γγB(M1)↑=2.7(3)μN2N=Z∑B(E1)↑≤0.61×10-322B(Π1,1iπ→21+)/B(Π1,1iπ→0gs+)24ρ2(E0,02+→0gs+)B(M1,1+→02+)/B(M1,1+→0gs+)1+Δβ2202+ nucleus exhibits only marginal E1 strength of less than N=Z2424γ,γ′Jπ=1-Jπ=1+Jπ=2+24γγB(M1)↑=2.7(3)μN2N=Z∑B(E1)↑≤0.61×10-322B(Π1,1iπ→21+)/B(Π1,1iπ→0gs+)24ρ2(E0,02+→0gs+)B(M1,1+→02+)/B(M1,1+→0gs+)1+Δβ2202+ eN=Z2424γ,γ′Jπ=1-Jπ=1+Jπ=2+24γγB(M1)↑=2.7(3)μN2N=Z∑B(E1)↑≤0.61×10-322B(Π1,1iπ→21+)/B(Π1,1iπ→0gs+)24ρ2(E0,02+→0gs+)B(M1,1+→02+)/B(M1,1+→0gs+)1+Δβ2202+fmN=Z2424γ,γ′Jπ=1-Jπ=1+Jπ=2+24γγB(M1)↑=2.7(3)μN2N=Z∑B(E1)↑≤0.61×10-322B(Π1,1iπ→21+)/B(Π1,1iπ→0gs+)24ρ2(E0,02+→0gs+)B(M1,1+→02+)/B(M1,1+→0gs+)1+Δβ2202+. The N=Z2424γ,γ′Jπ=1-Jπ=1+Jπ=2+24γγB(M1)↑=2.7(3)μN2N=Z∑B(E1)↑≤0.61×10-322B(Π1,1iπ→21+)/B(Π1,1iπ→0gs+)24ρ2(E0,02+→0gs+)B(M1,1+→02+)/B(M1,1+→0gs+)1+Δβ2202+ branching ratios in combination with the expected results from the Alaga rules demonstrate that K is a good approximative quantum number for N=Z2424γ,γ′Jπ=1-Jπ=1+Jπ=2+24γγB(M1)↑=2.7(3)μN2N=Z∑B(E1)↑≤0.61×10-322B(Π1,1iπ→21+)/B(Π1,1iπ→0gs+)24ρ2(E0,02+→0gs+)B(M1,1+→02+)/B(M1,1+→0gs+)1+Δβ2202+Mg. The use of the known N=Z2424γ,γ′Jπ=1-Jπ=1+Jπ=2+24γγB(M1)↑=2.7(3)μN2N=Z∑B(E1)↑≤0.61×10-322B(Π1,1iπ→21+)/B(Π1,1iπ→0gs+)24ρ2(E0,02+→0gs+)B(M1,1+→02+)/B(M1,1+→0gs+)1+Δβ2202+ strength and the measured N=Z2424γ,γ′Jπ=1-Jπ=1+Jπ=2+24γγB(M1)↑=2.7(3)μN2N=Z∑B(E1)↑≤0.61×10-322B(Π1,1iπ→21+)/B(Π1,1iπ→0gs+)24ρ2(E0,02+→0gs+)B(M1,1+→02+)/B(M1,1+→0gs+)1+Δβ2202+ branching ratio of the 10.712 MeV N=Z2424γ,γ′Jπ=1-Jπ=1+Jπ=2+24γγB(M1)↑=2.7(3)μN2N=Z∑B(E1)↑≤0.61×10-322B(Π1,1iπ→21+)/B(Π1,1iπ→0gs+)24ρ2(E0,02+→0gs+)B(M1,1+→02+)/B(M1,1+→0gs+)1+Δβ2202+ level allows, in a two-state mixing model, an extraction of the difference N=Z2424γ,γ′Jπ=1-Jπ=1+Jπ=2+24γγB(M1)↑=2.7(3)μN2N=Z∑B(E1)↑≤0.61×10-322B(Π1,1iπ→21+)/B(Π1,1iπ→0gs+)24ρ2(E0,02+→0gs+)B(M1,1+→02+)/B(M1,1+→0gs+)1+Δβ2202+ between the prolate ground-state structure and shape-coexisting superdeformed structure built upon the 6432-keV N=Z2424γ,γ′Jπ=1-Jπ=1+Jπ=2+24γγB(M1)↑=2.7(3)μN2N=Z∑B(E1)↑≤0.61×10-322B(Π1,1iπ→21+)/B(Π1,1iπ→0gs+)24ρ2(E0,02+→0gs+)B(M1,1+→02+)/B(M1,1+→0gs+)1+Δβ2202+ level.