
^{5}H (1959AJ76)(Not illustrated) The possible existence of a particlestable ^{5}H is discussed by (1957BL1A) who point out that a T = 3/2 level of ^{5}He  ^{5}Li might plausibly be formed by combination of ^{3}H or ^{3}He and a deuteron in the singlet (T = 1) state at an energy ≈ 2.3 MeV higher than the known 16.7  16.8 MeV level. If such a level exists, calculation of Coulomb corrections and n  ^{1}H mass difference suggests a mass excess of 32.22 MeV for ^{5}H, which would be 0.35 MeV stable against ^{3}H + 2n. Presumably ^{5}H would then decay by βemission (≈ 19 MeV) followed by neutron emission (1957BL1A). A search for delayed neutrons from ^{7}Li(γ, 2p)^{5}H with 320MeV bremsstrahlung yielded no evidence of formation of ^{5}H (1958TA1A). It is concluded that less than 1% of the expected yield of ^{7}Li(γ, 2p)^{5}H leads to a particlestable product (1958TA1A); see also (1958CE1A). A reaction yielding ^{5}H might be ^{3}H(t, p)^{5}H with Q ≈ 8.1 MeV, assuming the mass of ^{5}H given by (1957BL1A).
