The 5Be nucleus is particle unbound to proton decay; no resonances have been experimentally observed.
2013Ti01 gives 5Be mass defect as 34.10 MeV 12 by improved Kelson-Garvey systematics. Using this value for the 5Be mass defect, the ground state of 5Be would be 4.59 MeV 12 above the 3He+2p threshold.
The 2016 mass table (2017Wa10) gives the estimated mass defect of 5Be as 37.1 MeV 20. Using this value, the ground state of 5Be would be 7.6 MeV 20 above the 3He+2p threshold.
Negative experimental results:}
3He(3He,n)5Be:
1967Ad05: 3He beams from CIT and Stanford accelerators with energies from 18 MeV to 26 MeV collided with 3He in a gas target and the neutron spectrum measured. No structure was observed corresponding to 5Be states. It was concluded that any 5Be states must be at least 4.2 MeV above the 3He+2p threshold.
Theory:}
1981Be10: The author presented a shell model calculation of α=5 nuclei with the goal of testing the t=3/2 IMME for α=5. His calculated binding energy for 5Be is 1.5 MeV. This gives a mass defect of 35.7 MeV and a resonance energy of 6.2 MeV relative to the 3He+2p threshold. There is no mention of the Jπ value for the state.
2003Ar18: The authors used a three body cluster model with effective interactions that give reasonable results for other nearby nuclei as well as p+3He phase shifts. The authors suspect that the absence of a tensor component in their effective interaction may be of significance. They obtained the following results, where the resonance energies are given relative to the 3He+2p threshold.
Note that the 3/2+ and 5/2+ states are nearly degenerate and very broad and are not likely to show up in reactions as separate resonances.
The 5Be nucleus is particle unbound to proton decay; no resonances have been experimentally observed.
2013Ti01 gives 5Be mass defect as 34.10 MeV 12 by improved Kelson-Garvey systematics. Using this value for the 5Be mass defect, the ground state of 5Be would be 4.59 MeV 12 above the 3He+2p threshold.
The 2016 mass table (2017Wa10) gives the estimated mass defect of 5Be as 37.1 MeV 20. Using this value, the ground state of 5Be would be 7.6 MeV 20 above the 3He+2p threshold.
Negative experimental results:}
3He(3He,n)5Be:
1967Ad05: 3He beams from CIT and Stanford accelerators with energies from 18 MeV to 26 MeV collided with 3He in a gas target and the neutron spectrum measured. No structure was observed corresponding to 5Be states. It was concluded that any 5Be states must be at least 4.2 MeV above the 3He+2p threshold.
Theory:}
1981Be10: The author presented a shell model calculation of α=5 nuclei with the goal of testing the t=3/2 IMME for α=5. His calculated binding energy for 5Be is 1.5 MeV. This gives a mass defect of 35.7 MeV and a resonance energy of 6.2 MeV relative to the 3He+2p threshold. There is no mention of the Jπ value for the state.
2003Ar18: The authors used a three body cluster model with effective interactions that give reasonable results for other nearby nuclei as well as p+3He phase shifts. The authors suspect that the absence of a tensor component in their effective interaction may be of significance. They obtained the following results, where the resonance energies are given relative to the 3He+2p threshold.
Note that the 3/2+ and 5/2+ states are nearly degenerate and very broad and are not likely to show up in reactions as separate resonances.
See other more general theoretical analyses in (1975Be31, 1981Ka39, 1982Ng01, 2004Sa50)