The spin observables Ay, iT 11, and Cy,y in proton-deuteron elastic scattering were measured over the angular range 65° &thetas; cm 115° at a proton energy Tlab = 197 MeV. These data were acquired with a polarized proton beam and an internal vector-polarized deuteron gas target at the Indiana University Cyclotron Facility. The target was polarized by spin exchange with optically-pumped potassium; this experiment was the first to use this novel technique for polarizing hydrogen and deuterium. The data have been compared to existing Faddeev calculations using modern two-nucleon potentials which accurately reproduce the available two-nucleon scattering data. The calculations were also performed with the addition of the Tucson-Melbourne three-nucleon potential to identify kinematic regimes where the three-nucleon force makes a significant contribution. One such regime is in the vicinity of the minimum in the differential cross section for nucleon-deuteron elastic scattering at nucleon energies T lab 100 MeV, which includes the region covered by this experiment. The failure of calculations using only two-nucleon potentials to reproduce the results of this experiment is interpreted as evidence that some type of three-nucleon force is needed to explain the data.
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机译:自旋观测值 A y sub>,iT italic> 11 sub>和 C y,y sub> italic>在质子能量 T italic> lab sub> = 197 MeV的65°<&thetas; cm sub> <115°的角度范围内测量质子-氘核的弹性散射。这些数据是通过印第安纳大学回旋加速器设施上的极化质子束和内部矢量极化氘核气体靶获得的。通过与光学泵浦的钾自旋交换使靶极化。该实验是首次使用这种新技术极化氢和氘的实验。该数据已与使用现代两核子电势的现有Faddeev计算进行了比较,该计算准确地再现了可用的两核子散射数据。还通过添加图森-墨尔本三核子电位来进行计算,以识别三核子力作出重大贡献的运动学方案。一种这样的机制是在核能 T italic> lab sub> 展开▼