论文标题
巨型偶极子共振的起源
The Origin of the Giant Dipole Resonance
论文作者
论文摘要
巨型偶极子共振（GDR）通常将其描述为由于集体运动，而是被证明是2HΩ壳闭合处水平密度突然增加的结果。 GDR的能量紧随壳模型谐波振荡器能量模型，其中HΩ= 39A^-1/3，对于重核。覆盖整个质量范围的更好拟合由HΩ= 47:55（0:13）（a^-1/3 - a^-2/3）。 GDR被证明是由较低的能量峰E1组成的，该峰与扁平变形和较高能量峰的水平群体相对应，E2对应于具有pr酸变形的水平的种群。峰值分离与β_2变形成正比，由E2-E1 = 11:03（0:22）|β_2|给出。填充GDR的总光核横截面Sigma = Sigma1 + Sigma2与GDR处的水平密度成正比，由Sigma = 0：483（0：006）A^4/3给出，其中Sigma1 = Sigma2。两个GDR峰的宽度与NILSSON模型预测一致，发现分别为γ1= 7:41（0:15）A^-1/6 MeV和Gamma2 = 11:13（0:16）A^-1/6。标准Lorentzian模型参数是质量和变形的函数的高精度，并且可以可靠地应用于所有核。 It is shown that the energies of pygmy and spin flip resonances correspond to the E = hω harmonic oscillator energy and that the giant quadrupole (GQR), giant monopole (GMR), and giant octupole (GOR) resonances coincide with the E = 2-4 hω harmonic oscillator energies where the level density suddenly increases at the shell gaps.
The Giant Dipole Resonance (GDR), which is conventionally described as due to collective motion, is instead shown to be the result of a sudden increase in level density at the 2hω shell closure. The energy of the GDR closely follows the shell model harmonic oscillator energy model where hω = 39A^-1/3, for heavy nuclei. A better fit covering the entire mass range is given by hω = 47:55(0:13)(A^-1/3 - A^-2/3). The GDR is shown to be composed of a lower energy peak, E1, corresponding to the population of levels with oblate deformation and a higher energy peak, E2 corresponding to the population of levels with prolate deformation. The peak energy separation is proportional to the β_2 deformation and given by E2-E1 = 11:03(0:22)|β_2|. The total photonuclear cross section, sigma = sigma1 + sigma2, populating the GDR is proportional to the level density at the GDR and is given by sigma = 0:483(0:006)A^4/3 where sigma1 = sigma2. The widths of the two GDR peaks are consistent with Nilsson model predictions and found to be Gamma1 = 7:41(0:15)A^-1/6 MeV and Gamma2 = 11:13(0:16)A^-1/6 respectively. The Standard Lorentzian model parameters are fitt to high accuracy as a function of mass and deformation and can be applied reliably to all nuclei. It is shown that the energies of pygmy and spin flip resonances correspond to the E = hω harmonic oscillator energy and that the giant quadrupole (GQR), giant monopole (GMR), and giant octupole (GOR) resonances coincide with the E = 2-4 hω harmonic oscillator energies where the level density suddenly increases at the shell gaps.
