ADOPTED LEVELS for 7B
Authors: J. Kelley, C.G. Sheu | Citation: ENSDF | Cutoff date: 01-June-2014
Full ENSDF file | Adopted Levels (PDF version)
| S(n)= 27.7×103 keV 20 | S(p)= -2013 keV 25 | Q(α)= -3.4×103 keV 20 | |||
| Reference: 2012Wa38 |
| References: | |||
| A | 7Li(π+,π-) | B | 9Be(9C,7B) |
| C | 10B(3He,6He) | ||
| E(level) (keV) | XREF | Jπ(level) | T1/2(level) |
| 0 | ABC | (3/2-) | 801 keV 20 % p ≈ 100 |
Additional Level Data and Comments:
| E(level) | Jπ(level) | T1/2(level) | Comments |
| 0 | (3/2-) | 801 keV 20 % p ≈ 100 | T=(3/2) All decay paths emit protons. The intensity for decay to p+6Beg.s. is (81 ± 10)%. Proton decay to 6Be*(1.6 MeV) is suppressed. Decay to 2p+5Li and 3p+4He are other open channels. E(level): All decay paths emit protons. The intensity for decay to p+6Beg.s. is (81 ± 10)%. Proton decay to 6Be*(1.6 MeV) is suppressed. Decay to 2p+5Li and 3p+4He are other open channels. |
Evidence of the unbound 7B nucleus is observed in three measurements. Each of these measurements is complicated by backgrounds, which affect the extraction of ground state properties. Since 7B is unbound to 1p, 2p and 3p emission, the 7Li(π+,π-) measurements of (1981SeZR) are complicated by multi-body breakups that add a phase-space background component to their analyzed spectra. The 10B(3He,6He) measurements of (1967Mc14) were complicated by a rather large 11B(3He,6He) background of 8B states along with a multi-body breakup phase-space background component. Finally, the kinematically complete 7B analysis of 9Be(9C,7B) reactions of (2011Ch32) are "contaminated " by 9Be(9C,8C) events where one proton is unobserved.
The corrections applied in 2012Ch32 appear to be the smallest, and arguably most reliable, which perhaps explains that the 2012Wa38 mass evaluation has based the 7B mass excess on this value alone. Without further experimental information, it is agreed that this is the best decision.
Mass predictions and comparison with t=3/2 isobaric analog states are found in (1965De08, 1988Co15, 1997Po12, 2011Ch53). See (1974Ir04, 1993Po11, 1997Ba54, 1998Na17, 2001Co21, 2006Wi07, 2007Ma79) for broad analyses of 7B and other p-shell nuclei, and see (2006Ca35, 2007Do01, 2007Ca31, 2011My03, 2012My04) for more specific analysis on 7B and nearby nuclides.
The connection between wave-function diffuseness and proton decay is analyzed in 1997Ab27.