TY - GEN
T1 - Systematic analysis of inelastic alpha scattering off self-conjugate A = 4 N nuclei
AU - Adachi, Satoshi
AU - Kawabata, Takahiro
AU - Minomo, Kosho
N1 - Funding Information:
The authors acknowledge the RCNP cyclotron crews for providing a high-quality beam, which was essential for the present experiments. This work was performed under the RCNP E253, E308, E369, and E402 programs and partly supported by JSPS KAKENHI Grants No. JP15H02091 and No. JP23340068.
Publisher Copyright:
© 2018 Author(s).
PY - 2018/11/13
Y1 - 2018/11/13
N2 - The multipole decomposition analysis (MDA) for the inelastic alpha scattering is very useful to determine the strength distribution, and widely used to study the cluster structures in nuclei. However, the reliability of the MDA was shaken by the puzzle of the missing monopole strength in 12C, where the monopole strength for the Hoyle state determined by the inelastic alpha scattering is much smaller than by the inelastic electron scattering. In the present work, we systematically measured cross sections of the inelastic alpha scattering at Eα=130 and 386 MeV exciting low-lying discrete states in 12C, 16O, 20Ne, 24Mg, 28Si, and 40Ca. In addition, we compared the measured cross sections with the "parameter-free" distorted-wave Born-approximation (DWBA) calculation. All of the adjustable parameters in the DWBA calculation were determined by the electromagnetic transition strengths and the elastic alpha scattering. We found that this puzzle is not specific to the Hoyle state in 12C but universally observed in all of the ΔL = 0 transitions, and the DWBA calculation with the density-independent effective αN interaction at Eα = 386 MeV is better than that with the density-dependent effective αN interaction. The inadequate density dependence in the effective αN interaction causes this puzzle by overestimating the cross sections for the ΔL = 0 transition. However, it is still unsatisfactory to reproduce the experiment. The present data will provide valuable information to develop a new sophisticated interaction which includes the proper density depend.
AB - The multipole decomposition analysis (MDA) for the inelastic alpha scattering is very useful to determine the strength distribution, and widely used to study the cluster structures in nuclei. However, the reliability of the MDA was shaken by the puzzle of the missing monopole strength in 12C, where the monopole strength for the Hoyle state determined by the inelastic alpha scattering is much smaller than by the inelastic electron scattering. In the present work, we systematically measured cross sections of the inelastic alpha scattering at Eα=130 and 386 MeV exciting low-lying discrete states in 12C, 16O, 20Ne, 24Mg, 28Si, and 40Ca. In addition, we compared the measured cross sections with the "parameter-free" distorted-wave Born-approximation (DWBA) calculation. All of the adjustable parameters in the DWBA calculation were determined by the electromagnetic transition strengths and the elastic alpha scattering. We found that this puzzle is not specific to the Hoyle state in 12C but universally observed in all of the ΔL = 0 transitions, and the DWBA calculation with the density-independent effective αN interaction at Eα = 386 MeV is better than that with the density-dependent effective αN interaction. The inadequate density dependence in the effective αN interaction causes this puzzle by overestimating the cross sections for the ΔL = 0 transition. However, it is still unsatisfactory to reproduce the experiment. The present data will provide valuable information to develop a new sophisticated interaction which includes the proper density depend.
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U2 - 10.1063/1.5078850
DO - 10.1063/1.5078850
M3 - Conference contribution
AN - SCOPUS:85057215677
T3 - AIP Conference Proceedings
BT - Proceedings of the 4th International Workshop on State of the Art in Nuclear Cluster Physics, SOTANCP 2018
A2 - Folden, Charles M.
A2 - Goldberg, Vladilen Z.
A2 - Rogachev, Grigory V.
A2 - Barbui, Marina
PB - American Institute of Physics Inc.
T2 - 4th International Workshop on State of the Art in Nuclear Cluster Physics, SOTANCP 2018
Y2 - 13 May 2018 through 18 May 2018
ER -