ADOPTED LEVELS for 5H
Authors: J.E. Purcell, C.G. Sheu | Citation: ENSDF | Cutoff date: 28-Feb-2019
Full ENSDF file | Adopted Levels (PDF version)
| Q(β-)=2.166×104 keV 9 | S(n)= -2.0×102 keV 13 | ||||
| Reference: 2017WA10 |
| References: | |||
| A | 1H(6He,2He) | B | 2H(6He,3He) |
| C | 3H(t,p) | D | 6Li(π-,p) |
| E | 7Li(π-,d) | F | 7Li(6Li,8B) |
| G | 9Be(π-,PT) | H | 9Be(π-,DD) |
| I | 9Be(α,8B) | J | 9Be(11B,15O) |
| K | 11B(π-,D4HE),10B(π-,P4HE) | L | C(6He,5H) |
| E(level) (keV) | XREF | Jπ(level) | T1/2(level) |
| 0 | ABC L | (1/2+) | 5.3 MeV 4 % 2n ≈ 100 |
| 3.1E3 6 | GH K | 5.3 MeV 5 % 2n ≈ 100 | |
| 8.1E3 6 | DE GHI K | 6.8 MeV 6 % 2n ≈ 100 | |
| 16.1E3 5 | GH | 4.8 MeV 17 % 2n ≈ 100 | |
| 24.4E3 5 | GH | 3.5 MeV 14 % 2n ≈ 100 |
Additional Level Data and Comments:
| E(level) | Jπ(level) | T1/2(level) | Comments |
| 0 | (1/2+) | 5.3 MeV 4 % 2n ≈ 100 | Eres(3H+2n)(MeV)=2.4 3. |
| 3.1E3 | 5.3 MeV 5 % 2n ≈ 100 | Eres(3H+2n)(MeV)=5.5 3. | |
| 8.1E3 | 6.8 MeV 6 % 2n ≈ 100 | Eres(3H+2n)(MeV)=10.5 4. | |
| 16.1E3 | 4.8 MeV 17 % 2n ≈ 100 | Eres(3H+2n)(MeV)=18.5 4. | |
| 24.4E3 | 3.5 MeV 14 % 2n ≈ 100 | Eres(3H+2n)(MeV)=26.8 4. |
As the following theoretical and experimental articles indicate, the ground state of 5H has Jπ=1/2+ and is located around 2 MeV above the 3H+2n threshold and has a width greater than 1 MeV. Broad and nearly degenerate excited states with Jπ=3/2+ and 5/2+ are predicted a few MeV above the ground state; however, the experimental results are not sufficient to describe the excited states in great detail.
{Suggestion of a bound 5H ground state:}
In the theoretical work of [Blanchard and Winter, Phys. Rev. 107 (1957) 774 ] titled "Is 5H Particle Stable ", it was suggested that 5Hg.s. may be bound and observable with Eβ≈19 MeV followed by a delayed neutron emission. Subsequent searches for β unstable 5H were carried out utilizing 7Li(γ,2p) (1962Ce03: Berkeley, 1963Ne02: Purdue, 1964Sh18: Orsay, 1965Ar04: Frascati), 7Li(p,3p) reactions (Tautfest, Phys. Rev. 111 (1958) 1162 and 1958Ta03: Berkeley, 1964Sc02: Brookhaven), 7Li(π-,d) (1968Bo32: Univ. Chicago) and analysis of the 235U(n,f) yields (1964An06: USSR).
An erroneous result obtained in the Ebrem.(γ)=320 bombardment of natLi at Purdue suggested population of a T1/2=110 ms 30 β emitter with Eβ>15 MeV that was attributed to 5H (1963Ne02). The experiments following (1963Ne02) mainly searched for a reasonably narrow and bound 5H ground state. However, no evidence of β unstable 5H was found in any subsequent study. The sentiment is well represented in the title Still another unsucessful search for 5H: (1968Bo32).
General theoretical analyses, favoring an unbound 5Hg.s. are given in (1960Go36, 1960Ze03, 1963Ar06, 1964Go25, 1968Go36, 1975Be49, 1981Av02, 1981Be10, 1981Ka39, 1989Go24, 2001Fi24, 2002Ti05, 2004Ao05, 2004Gr03, 2004Ti02, 2018Gr02).
See a broad review of the experimental data in (2004Gr17).
It is pointed out in (2017Wu03) that the structure of 5H plays an important role in the hypernucleus 6|LH. See the discussion in the following reaction 2H(6He,3He).