Search for the 6$\alpha$ condensed state in ${}^{24}$Mg using the ${}^{12}\mathrm{C}+{}^{12}\mathrm{C}$ scattering

Abstract

We searched for the 6$\alpha$-condensed state in ${}^{24}$Mg by measuring the ${}^{12}\mathrm{C}+{}^{12}\mathrm{C}$ scattering with the SAKRA Si detector array at $E_\rm{cm}$ = 17.5-25.0 MeV. By using the invariant-mass method for the detected 3$\alpha$ particles, the inclusive cross sections for the ${}^{12}\mathrm{C}+{}^{12}\mathrm{C}\to {}^{12}\mathrm{C}(0_2^{+})+\mathrm{X}$ and ${}^{12}\mathrm{C}(3_1^{-})+\mathrm{X}$ reactions were determined. In addition, the missing-mass spectroscopy was successfully utilized to determine the excitation energy of the residual ${}^{12}\mathrm{C}$ nucleus and the exclusive cross sections for the ${}^{12}\mathrm{C}+{}^{12}\mathrm{C}\to {}^{12}\mathrm{C}(0_2^{+})+{}^{12}\mathrm{C}(0_1^{+})$, ${}^{12}\mathrm{C}(0_2^{+})+{}^{12}\mathrm{C}(2_1^{+})$, and ${}^{12}\mathrm{C}(0_2^{+})+{}^{12}\mathrm{C}(0_2^{+})$ reactions. In both the inclusive ${}^{12}\mathrm{C}(0_2^{+})+\mathrm{X}$ channel and the exclusive ${}^{12}\mathrm{C}(0_2^{+})+{}^{12}\mathrm{C}(0_1^{+})$ channel, the cross section peaked at $E_{r}mcm$ = 19.4 MeV, which correspond to the excitation energy of $E_x$ = 33.3 MeV in ${}^{24}\mathrm{Mg}$. This 19.4-MeV state is a candidate for the 6$\alpha$-condensed state because of the agreement of the excitation energy with the theoretical value and its decay property. In the exclusive ${}^{12}\mathrm{C}(0_2^{+})+{}^{12}\mathrm{C}(0_2^{+})$ channel, a broad state was observed at $E_\rm{cm}$ = 22.5 MeV, which correspond to the excitation energy of $E_x$ = 36.4 MeV in ${}^{24}\mathrm{Mg}$. From the angular distribution of the differential cross section, the spin and parity of this 22.5-MeV state was assigned to be $4^{+}$. In addition, a $2^{+}$ state was suggested at the low-energy side of the 22.5-MeV state. Because their excitation energies are higher than the theoretical value of the 6$\alpha$-condensed state, these states might be excited states of the 6$\alpha$-condensed state such as the $2_2^{+}$ and $4_1^{+}$ states in ${}^{12}\mathrm{C}$.

arXiv comment8 pages, 6 figures

References in corpus (16)

• Alpha cluster condensation in 12C and 16O
• Alpha-particle condensation in 16O via a full four-body OCM calculation
• Unambiguous Identification of the Second 2+ State in 12C and the Structure of the Hoyle State
• Dilute Multi Alpha Cluster States in Nuclei
• Single $\alpha$-particle orbits and Bose-Einstein condensation in ${}^{12}$C
• Description of 8Be as Deformed Gas-like Two-Alpha-Paricle States
• Isoscalar monopole excitations in ${}^{16}$O: $\alpha$-cluster states at low energy and mean-field-type states at higher energy
• Hoyle band and $\alpha$ condensation in ${}^{12}\mathrm{C}$
• Experimental investigation of $\alpha$-condensation in light nuclei
• Candidates for the 5$\alpha$ condensed state in ${}^{20}$Ne
• Container evolution for cluster structures in ${}^{16}\mathrm{O}$
• Nuclear Alpha-Particle Condensates
• Searching for states analogous to the 12C Hoyle state in heavier nuclei using the thick target inverse kinematics technique
• Alpha-cluster Condensations in Nuclei and Experimental Approaches for their Studies
• Alpha-particle condensation: a nuclear quantum phase transition
• Phase diagram of alpha matter with Skyrme-like scalar interaction

Cited by in corpus (3)

• Shape of 12C
• Symplectic symmetry approach to clustering in atomic nuclei: The case of ${}^{24}$Mg
• Six-$\alpha$ cluster Bose-Einstein condensation and supersolid ${}^{12}$C($0_2^{+})$+${}^{12}$C($0_2^{+})$ molecular structure in ${}^{24}$Mg