8B

β+-Decay Evaluated Data



Measurements
1950AL57: 8B; measured T1/2.
1952SH44: 8B; measured T1/2.
1953HO01: 8B; measured T1/2.
1958DU78: 8B; measured T1/2.
1958VE20 : 8B; measured T1/2.
1959FA02: 8B; measured T1/2.
1964MA35: 8B; measured not abstracted; deduced nuclear properties.
1971WI05: 8B; measured delayed α spectra, T1/2; deduced no 2nd-class current contribution.
1973MCZW: 8B; measured T1/2.
1986WA01: 8B(β+); analyzed β-delayed breakup α-spectra; deduced intruder states role. 8Be deduced level, Γ, Gamow-Teller matrix elements. R-matrix.
1987NA08: 8B(β+); measured positron momentum spectrum. 8B deduced ν(e) energy spectrum.
1990MAZA: 8B(β+); measured NMR, β-ray asymmetry. 8B deduced electric quadrupole moment.
1991SOZW: 8B(β+); measured NMR, β asymmetry. 8B deduced quadrupole moment.
1992MI18: 8B(β+); measured β-NMR, deduced quadrupole moment, proton halo characteristics.
1992TAZP: 8B(β+); measured T1/2. 8Be, deduced levels, ft-value asymmetries.
1993MI36: 8B(β+); measured modified β-NMR spectra; deduced quadrupole moment.
1996OHZY: 8B(β+); measured β-NMR. 8B deduced μ, quadrupole moment.
1997HAZQ: 8B(β+); measured α-decay anisotropy, β'-ray polarization. 8B deduced positive sign of quadrupole moment.
2000OR04: 8B(β+); measured β-delayed α spectrum; deduced neutrino spectrum.
2002BH03: 8B(EC); analyzed β-delayed Eα. 8Be deduced R-matrix parameters.
2002MO44: 8B(β-); measured β-asymmetry.
2002REZU, 2002WIZX, 2003SCZX, 2003WI11, 2003WI16, 2004WI13, 2004WIZZ, 2006WI03: 8B(β+), (β+α), (EC); measured β-delayed Eα, αα-coin; deduced β+-decay strength function, neutrino spectrum.
2004BB06: 8B(β+); measured β-delayed Eα, βγ-coin; deduced upper limit for ground-state transition branching ratio.
2004RE07: 8B(β+), (EC); measured β-delayed Eα; deduced neutrino spectrum.
2004SU29: 8B(β+α); measured Eβ, βα-coin, angular correlations following decay of polarized source; deduced alignment correlation terms.
2005SU25: 8B(ECα); measured β-NMR spectra; angular correlations; deduced limit on G-parity term.
2006BAZV: 8B(β+); measured Eβ; deduced ground-state transition branching ratio.
2006BH03: 8B(β+α); measured β-delayed Eα; deduced final-state continuum shapes. R-matrix analysis.
2006SU13: 8B(β+), (EC) measured β-NQR spectrum from oriented source. 8B deduced electric quadrupole moment.
2007BA75: 8B(β+); measured delayed α particles, branching ratio to the ground state of 8Be.
2007SUZX: 8B(β+α); measured β(θ, H, t) from polarized sources.
2010KIZU: 8B(β+); measured Eα, Eα, αα-coin; deduced relative null σ(E).
2011KI14: 8B(β+α); measured β spectra, β-delayed α spectra, Eα, αα-coin. 8Be; deduced excitation distribution.
2012RO10: 8B(β+α); measured decay products, Eα, Iα, Eβ, Iβ; deduced final state distribution in 8Be, J, π, neutrino spectrum. Comparison with available data, R-matrix fits.
2013BO06: 8B(β+p); analyzed available data; calculated beta-delayed proton emission.
2020BA07: compiled β+-delayed proton (or α) emission for very neutron-deficient nuclei, J, π, T1/2, branching ratios.
Measured half-life for 8B(β+)8Be

Recommended value (August, 2020): 772.1 ± 1.7 ms
Summary Table of Uncertainty Analysis:       Table 08B preview (PDF) Graph of Life-Time: Graph 08B preview (PDF)
Measured values: 771.9 ± 1.7 ms (2020VI03)
773.9 ± 1.8 ms (2020VI03)
770.9 ± 2.7 ms (2020VI03)
772 ± 4 ms (1973MCZW)
762 ± 5 ms (1971WI05)
774 ± 5 ms (1964MA35)
  790 ± 20 ms (1959FA02)
  780 ± 10 ms (1958DU78)
  750 ± 20 ms (1958VE20)
  460 ± 30 ms (1953HO01) (Excluded)
    610 ± 110 ms (1952SH44)
    650 ± 100 ms (1950AL57)
Other Reviews: 770.3 ± 4.0 ms (Our analysis in July, 2015)

Previous Measurements

 

Decay to
8Be* (MeV)
Branching Ratio (%) Log ft
(1958VE20) (1952KI1A) (1958VE20) (1964MA35) (1969BA43) (1966BA1A) (1989BA31)
0 < 5%     > 7.3             
  3.0 ≈ 80% 5.54 5.72     5.64 a 5.77
11.7   ≈ 11% b   4.6          
    16.63 c       2.9 3.33    
a) Taking T1/2 = 774 ms, Q = 17.979 - 2.90 and B. Zimmerman, private communication to Fay Ajzenberg-Selove (1974AJ01).
b) For transition to higher states, possibly 8Be*(11.7).
c) (1964MA35) observe a branch to a 8Be state at ≈ 16.6 MeV.

8He(β-)8Li Evaluated Data

8Li(β-)8Be Evaluated Data

A = 8 Beta-Decays Diagram

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Last modified: 24 June 2021