Measurement of the PNC spin-rotation of transversely polarized neutrons travelling through liquid ^4He
Abstract
We are preparing a second-generation experiment to measure the parity-violating (PNC) spin rotation of a transversely polarized cold neutron beam as it passes through a target of liquid helium. In the low-energy weak nucleon-nucleon (NN) meson exchange theory, this PNC rotation, φ_PNC(n,α), is primarily sensitive to a linear combination of the weak isovector π-exchange amplitude f_π and weak isoscalar ρ-exchange amplitude h^0_ρ. The linear combination of weak couplings which would be constrained by φ_PNC(n,α), is orthogonal to both the constraints from existing measurements of the longitudinal analyzing power of polarized protons in ^4He, A_L(p,α) [J. Lang et al, Phys. Rev. C 34, 1545 (1986)], and the constraint from measurements of the ^133Cs anapole moment [C. S. Wood et al, Science 275, 1759 (1997)]. The previous version of this experiment measured φ_PNC (n,α) = (8.0 14(stat) 2.2(syst)) × 10-7 rad/m [D. Markoff, PhD thesis, University of Washington]. We will present a brief outline of the physics issues, describe the design of the experiment, and summarize the current status.
- Publication:
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APS Division of Nuclear Physics Meeting Abstracts
- Pub Date:
- October 2002
- Bibcode:
- 2002APS..DNP.GF011B