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dc.contributor.advisor Snow, William M en
dc.contributor.author Bass, Christopher en
dc.date.accessioned 2010-06-03T17:56:18Z
dc.date.available 2010-10-19T17:47:51Z
dc.date.issued 2010-06-03T17:56:18Z
dc.date.submitted 2008 en
dc.identifier.uri http://hdl.handle.net/2022/7886
dc.description Thesis (PhD) - Indiana University, Physics, 2008 en
dc.description.abstract In the forward elastic scattering of transversely polarized neutrons propagating through a medium, the most prominent parity-violating observable is the rotation of the neutron spin vector about its momentum vector, which is due to the nucleon-nucleon (NN) weak interaction. A phenomenological model for the NN weak interaction uses nucleons and mesons as the important degrees of freedom, but values for the nucleon-meson weak coupling amplitudes are not well constrained by measurement or theory. A measurement of the parity-violating spin rotation of cold neutrons passing through liquid helium enables a quantitative theoretical interpretation of the poorly-understood properties of the NN weak interaction. Additionally, parity-violating neutron spin rotation in liquid helium is sensitive to the weak neutral current, which is not well-known from the current nuclear data set. The measurement is conducted by introducing a liquid helium target between a neutron polarizer/analyzer pair and manipulating the target and neutron spin to isolate the parity-violating rotation in the presence of much larger parity-conserving rotations due to residual magnetic fields. A previous measurement was performed in 1996 at the NIST Center for Neutron Research in Gaithersburg, Maryland with the result (8.0 +\- 14[stat] +\- 2.2[syst] ) x 10^-7 rad/m We describe a redesigned apparatus that can use superfluid helium to increase statistics and the installation of additional magnetic shielding to reduce systematics in an effort to reach a sensitivity goal of 3 x 10^-7 rad/m at NIST with an upper bound of 1 x 10^-7 rad/m on systematic effects. We describe the apparatus, the design of the new liquid helium target, and show preliminary data from this ongoing experiment. en
dc.language.iso EN en
dc.publisher [Bloomington, Ind.] : Indiana University en
dc.subject hadronic weak interaction en
dc.subject nucleon nucleon weak interaction en
dc.subject parity-violation en
dc.subject neutron optics en
dc.subject cold neutrons en
dc.subject.classification Physics, Nuclear en
dc.title Measurement of the parity-violating spin-rotation of polarized neutrons propagating through liquid helium en
dc.type Doctoral Dissertation en


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