Parity Nonconserving Spin Rotations Of The Neutron

点击翻译按钮获取中文摘要

***9804038HeckelA goal of modern physics is to understand and characterize the forces that are at work in nature. A missing element of this program is the determination of the weak interaction strength between the neutrons and protons in an atomic nucleus. The signature of the weak interaction is the violation of parity (left-right) symmetry. We propose to send a beam of polarized neutrons from the National Institute of Standards and Technology reactor through a one meter long target of liquid helium. The weak force between the neutrons in the beam and the helium nuclei (alpha particles) will cause the beam polarization to rotate about the beam direction in a right or left handed screw sense, by approximately one millionth of a degree. We propose to measure this minute "parity nonconserving rotation of the neutron spin" to extract the sign and strength of the weak force between neutrons and helium nuclei. Our result will be compared to the results from similar experiments with proton beams to provide a more complete characterization of the weak nuclear force. ***