Confirmation of parity violation in the {gamma} decay of {sup 180}Hf{sup m}

Journal Article · Wed Aug 15 04:00:00 EDT 2007 · Physical Review. C, Nuclear Physics

DOI:https://doi.org/10.1103/PHYSREVC.76.025502· OSTI ID:21062004

Stone, J R ^[1]; Goldring, G; Hass, M; Lakshmi, S ^[2]; Stone, N J ^[1]; Severijns, N; Kraev, I S; Wauters, F ^[3]; Zakoucky, D ^[4]; Giles, T; Lindroos, M ^[5]; Koester, U ^[6]

---

1. Department of Physics, University of Oxford, Oxford, OX1 3PU (United Kingdom)
2. The Weizmann Institute of Science, Rehovot (Israel)
3. K.U. Leuven, Instituut voor Kern-en Stralingfysica, B-3001 Leuven (Belgium)
4. Nuclear Physics Institute, ASCR, 25068 Rez (Czech Republic)
5. AB Department, CERN, CH-1211 Geneva 23 (Switzerland)
6. Institut Laue Langevin, 6 rue Jules Horowitz, F-38042 Grenoble Cedex 9 (France)

This paper reports measurements made using the technique of online nuclear orientation which reexamine the {gamma} decay of isomeric {sup 180}Hf{sup m} and specifically the 501 keV 8{sup -}6{sup +} transition. The irregular admixture of E2 to M2/E3 multipolarity in this transition, deduced from the forward-backward asymmetry of its angular distribution, has for decades stood as the prime evidence for parity mixing in nuclear states. The experiment, based on ion implantation of the newly developed mass-separated {sup 180}Hf{sup m} beam at the CERN online isotope mass separator (ISOLDE) facility into an iron foil maintained at millikelvin temperatures, produces higher degrees of polarization than were achieved in previous studies of this system. The value found for the E2/M2 mixing ratio, {epsilon}=-0.0324(16)(19), is in close agreement with the previous published average value {epsilon}=-0.030(2), in full confirmation of the presence of the irregular E2 admixture in the 501 keV transition. The temperature dependence of the forward-backward asymmetry has been measured over a more extended range of nuclear polarization than previously possible, giving further evidence for parity mixing of the 8{sup -} and 8{sup +} levels and the deduced E2/M2 mixing ratio.

• OSTI ID: 21062004
• Journal Information: Physical Review. C, Nuclear Physics, Journal Name: Physical Review. C, Nuclear Physics Journal Issue: 2 Vol. 76; ISSN 0556-2813; ISSN PRVCAN
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ANGULAR DISTRIBUTION
ASYMMETRY
E2-TRANSITIONS
E3-TRANSITIONS
GAMMA DECAY
HAFNIUM 180
ION IMPLANTATION
IRON
ISOTOPE SEPARATION
KEV RANGE
M2-TRANSITIONS
MIXING RATIO
MULTIPOLARITY
ORIENTATION
P INVARIANCE
PARITY
POLARIZATION
TEMPERATURE DEPENDENCE