A polarized beams project at ISAC

Levy, C.D.P.; Baartman, R.; Jayamanna, K.; Kiefl, R. F.; Kuo, T.; Olivo, M.; Wight, G. W.; Yuan, D.; Zelenski, A.

doi:10.1016/s0375-9474(01)01593-7

Cited by 19 publications

(22 citation statements)

References 3 publications

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“…= 4.277 MeV) and 27 Mg (Q − β = 2.61 MeV) contaminated the low-energy part of the 20 F spectrum. 20 Na decays to the excited states in 20 Ne at 7.421 MeV (16.4%), which was detected in addition to the decay to the first excited state at 1.634 MeV (79.3%). Contributions from those β decays to the alignment correlation terms were corrected in the analysis.…”

Section: β-Ray Detection Systemmentioning

confidence: 95%

“…Experiments on 20 F and 20 Na were performed at the Tandem Accelerator Complex of the University of Tsukuba (UTTAC) and at the Isotope Separator and Accelerator (ISAC) facility at TRIUMF, respectively. The alignment correlation terms were extracted from the difference between energy spectra measured with positive and negative alignments, which were produced by converting nuclear polarization into alignment using the β-nuclear magnetic resonance (NMR) technique.…”

Section: Methodsmentioning

confidence: 99%

“…For β decays of ground states 20 F(I π = 2 + , T = 1) and 20 Na(I π = 2 + , T = 1) to the first excited 1.634-MeV state in 20 Ne(I π = 2 + , T = 0), the alignment correlation term, B 2 /B 0 , is given by…”

Section: β-Decay Correlation Termsmentioning

confidence: 99%

“…For β decays of ground states of 20 F and 20 Na to the first excited state in 20 Ne and subsequent γ decay to the ground state of 20 Ne(I = 0 + , T = 0), the β-γ angular correlation term, p(E), is given by…”

Section: β-Decay Correlation Termsmentioning

confidence: 99%

“…Singly charged 20 Na ions were extracted at an energy of 40.8 keV and mass separated. The pure 20 Na beam was transported to the polarizer beam line [20] in the ISAC-I experimental hall. The ion beam was first passed through a Na-vapor cell and partially neutralized by charge exchange.…”

Section: Namentioning

confidence: 99%

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Low-energy test of second-class current inβdecays of spin-aligned20F and20Na

et al. 2011

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The G-parity-violating, second-class current-(SCC) induced tensor term in the weak-nucleon axial-vector current was determined from β-decay correlation measurements of the mass A = 20 mirror pair. The alignment correlation terms in the β-decay angular distribution from the purely spin aligned mirror pair, 20 F and 20 Na, were measured in the present study. Combining the present results with existing results of β and delayed γ -ray angular correlation measurements for the A = 20 mirror pair, the SCC-induced tensor term was extracted to be d II /Ac = 0.18 ± 0.48. In the extraction, the weak-magnetism term, b/Ac = 8.58 ± 0.28, evaluated from the M1 analog γ -ray decay strength, was used in a framework of the conserved vector current hypothesis. This is the first unambiguous extraction of the (b − d II )/Ac term free from the contribution of the second-forbidden form factor, j 2 , in the axial-vector current, which was a limiting factor for accurate determination of nonexistence of the SSC in the β decay of the A = 20 system. K. MINAMISONO et al. PHYSICAL REVIEW C 84, 055501 (2011) cancellations [5,10], possibly due to uncertainties in the nuclear structure. Therefore, the search for violation should be undertaken in various mass systems. For this purpose, β-decay correlation measurements were performed in the A = 8 (β-α angular correlation) [11,12] and A = 20 (β-γ angular correlation) [13-17] mirror systems. The β-decay correlation terms were formulated to first order of recoil terms in Ref. [7] and expressions taken in the reference will be used hereafter in this article. Unambiguous extraction of SCC from those correlation measurements, however, has been rather difficult due to imperfect knowledge of the M1/E2 mixing ratio of M1 analog γ decays and poor statistical error of the γ -ray decay strengths, from which a second-forbidden form factor, f , in the vector current is evaluated under an assumption of CVC.An alternative procedure to extract the SCC-induced tensor term was recently introduced in the A = 8 system [18], where the alignment correlation terms in the β-decay angular distribution from nuclear-spin aligned 8 Li and 8 B were combined with the β-α angular correlation terms. The (b − d II )/Ac term and other coupling constants associated with higherorder matrices are independently determined by fitting both correlation terms simultaneously. Here b/Ac is the weak magnetism, d II /Ac is the SCC-induced tensor term with c being Gamow-Teller form factor and g T /g A = d II /Ac. This procedure, combining both correlation terms, is a more reliable way to extract the (b − d II )/Ac term than that with a single correlation measurement. It is noted that the SCC-induced tensor term always appears with the weak magnetism in those correlation type measurements, and therefore, precise extraction of the SCC-induced tensor term is possible only when the weak magnetism is well known.The alignment correlation terms of the A = 20 system, 20 F(I π = 2 + , T 1/2 = 11.07 s) and 20 Na(I π = 2 + , T 1/2 = 447.9 ms), were m...

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Section: β-Ray Detection Systemmentioning

confidence: 95%

Section: Methodsmentioning

confidence: 99%