New interactions perturbing beta neutrino correlations

利用TRIUMF的原子阱进行核β衰变（TRINAT），我们测量了在37 K下相对于核自旋的β不对称性，Abeta为-0.5707+-0.0019。这是任何原子核或中子中最精确的β不对称测量，并且与粒子物理学标准模型的预测一致。目前，标准模型对Abeta的预测受限于两个允许的算符费米和伽莫夫-泰勒的相对贡献的实验测定。我们寻求改进的两个可观的依赖于各种衰变产物的动量，是独立的费米/伽莫夫-泰勒比。能量依赖性Abeta[Ebeta]正在从我们的项目资助和去年的RTI中实施，以改善自旋极化并升级该实验以接受较低能量的beta。 因此，我们寻求改进在这个RTI在真空中的离子检测仪器，使一个新的和互补的实验上的自旋不对称的反冲核在单打，沿着与β-反冲巧合，甚至更少依赖于理论校正。 单粒子中的反冲不对称性将具有非常高的统计数据，并且有望在现有的β衰变测量中对某些类型的相互作用的灵敏度提高一个数量级。 *** 我们新的加拿大理科硕士学生将为仪器理科硕士实施这一设备，这样就能拿到博士学位在这些实验中。我们继续提供机会，一次一个本科生，以帮助我们开发仪器和学习背景物理。* 我们还希望开始一个辐射β衰变中时间反演破坏的实验。这种3动量的相关性不涉及自旋，放松了涉及自旋的实验（如电偶极矩搜索）对它的限制。我们正在申请资金购买简单的伽马射线探测器，以补充现有的TRINAT仪器。

Using TRIUMF's atom trap for nuclear beta decay (TRINAT), we have measured the beta asymmetry with respect to the nuclear spin in 37K, Abeta, to be -0.5707+-0.0019. This is the most accurate beta asymmetry measurement in any nucleus or the neutron, and is in agreement with the prediction of the Standard Model of particle physics.***The standard model prediction for Abeta is presently limited by experimental determination of the relative contributions of the two allowed operators, Fermi and Gamow-Teller. We seek improvements of two observables that depend on the momentum of the various decay products, and are independent of the Fermi/Gamow-Teller ratio. The energy dependence Abeta[Ebeta] is being implemented from our project grant and last year's RTI to improve the spin polarization and upgrade this experiment to accept lower-energy betas.****** We thus seek improvements in this RTI to in-vacuum ion detection instrumentation to enable a new and complementary experiment on the spin asymmetry of the recoiling nuclei in singles, along with beta-recoil coincidences that are even less dependent on theoretical corrections. The recoil asymmetry in singles would have very high statistics, and holds the promise of an order of magnitude improvement in sensitivity over existing beta decay measurements to certain types of interactions. *** Our new Canadian M.Sc. student would implement this equipment for an instrumental M.Sc., which should lead to a Ph.D. project on these experiments. We continue to provide opportunities to one undergrad at a time to help us develop the instrumentation and learn the background physics.****** *We also wish to begin an experiment in time-reversal violation in radiative beta decay. This correlation of 3 momenta does not involve spin, relaxing constraints on it from experiments involving spin (like electric dipole moment searches). We are applying for funds for simple gamma-ray detectors to add to the present TRINAT apparatus.**