Test of parity violation in {sub 207}Pb by nuclear orientation

Journal Article · Fri Oct 01 04:00:00 EDT 1993 · Bulletin of the American Physical Society

OSTI ID:386955

Girit, I C; Petrov, M; Deptuck, D; Lowry, M M; Szymanski, J J; Bowman, J D

A measurement of parity nonconserving (PNC) asymmetries in the scattering of low energy polarized neutrons from {sup 232}Th showed large asymmetries, most of them having the same sign. Several theoretical calculations require that either there is a significant enhancement of PNC effects in heavy nuclei, or there is a misunderstanding of the reaction mechanism involved in these experiments. Study of PNC matrix elements in a heavy nucleus like {sup 207}Pb by a different method can differentiate between these two possibilities. The 1.063MeV, 13/2{sup +} to 5/2{sup -}{gamma} transition in {sup 207}Pb can have an {open_quotes}irregular{close_quotes} E4 multipole, due to a 5/2{sup +} admixture into the 5/2{sup -} state. The measurement of forward-backward asymmetry of this {gamma}-ray from the decay of polarized {sup 207}Bi nuclei will give the magnitude of the PNC effect. The forward-backward asymmetry in this line might be 3x10{sup -4}. In preliminary experiments, a {sup 207}Bi radioactive source dissolved in a Ni foil and cooled to 7mK showed a 50% parity allowed 0{degrees} enhancement for this {gamma}-ray. Ge detectors placed at 0{degrees} and 180{degrees}with respect to an external magnetic field will be used to measure the asymmetry.

• OSTI ID: 386955
• Report Number(s): CONF-931044--
• Journal Information: Bulletin of the American Physical Society, Journal Name: Bulletin of the American Physical Society Journal Issue: 9 Vol. 38; ISSN 0003-0503; ISSN BAPSA6
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
GAMMA DECAY
LEAD 207
NEUTRON REACTIONS
P INVARIANCE
POLARIZED BEAMS
SYMMETRY BREAKING
THORIUM 232