Production and assignment of ²⁵⁴No isotope:

1958Gh40, 1966Do04: parent of ²⁵⁰Fm; chemistry

1966Do04: ²³⁸U(²²Ne,6n); excitation function

1966Za04: ²⁴³Am(¹⁵N,4n); parent of ²⁵⁰Fm

1967Gh01: ²⁴⁶Cm(¹²C,4n); excitation function

1967Mi03: ²⁴²Pu(¹⁶O,4n); excitation function

1988Tu07: ²⁰⁸Pb(⁴⁸Ca,2n); chemistry; grandparent of ²⁴⁶Cf

Consult the NSR database at www.nndc.bnl.gov for numerous papers since 1988 for the production cross sections of ²⁵⁴No in different reactions

2018It04: measured mass excess=84675 keV 42(stat) 19(syst) using multireflection time-of-flight mass spectrograph at GARIS-RIKEN facility. This value can be compared to evaluated mass excess of 84723.4 keV 93 in 2017Wa10

2012Mi27: measured mass excess using time-of-flight ion-cyclotron-resonance method

2010Bl04, 2010Bl03, 2010Dw01: measured mass using SHIPTRAP Penning trap spectrometer at GSI

Theoretical studies: consult the NSR database at www.nndc.bnl.gov for 100 references dealing with theoretical calculations of half-lives for different decay modes, binding energies, fission characteristics, level properties, moments and deformations.

Levels: The decay scheme of the 184-μs isomer has been studied by 2010He10 at GSI, and by 2010Cl01 at LBNL. Very different decay schemes were proposed in the two experiments, although a similar rotational band, but with different Jπ values and configuration, was assigned in both the studies. 2016WaZW conducted an independent experiment at Jyvaskyla (JYFL) to resolve the difference between the two studies. The author favored the decay scheme given by 2010He10, with a possible difference that the 605-keV transition deexcited the isomer directly rather than through an intermediate level as suggested by 2010He10. However, 2016WaZW concluded with the following statement about the 605-keV transition: "The 605 keV rays seen at the focal plane in coincidence with the decay of the fast isomer confirm that there is a transition with this energy in ²⁵⁴No somewhere between the two isomers, but it does not give any more information about where in the level scheme the transition should be placed. Any of the level schemes in figure 9.1 is consistent with this observation ". Evaluator also consulted Prof. R.-D. Herzberg, thesis advisor of 2016WaZW, as well as the first author of 2006He19 paper for his opinion on the current status of the decay scheme of this isomer. Evaluator was advised (ref. e-mail reply of June 19, 2017 from Prof. Herzberg) that at this time, no definite decay scheme could be adopted, and that future experiments with more advanced detector arrays are needed to investigate the decay scheme between the two isomers: 184 μs and 265 ms. Thus, while the two currently proposed decay schemes are presented in this evaluation as separate datasets, no decay scheme has been adopted in this dataset.

Q-value: Estimated uncertainties (2017Wa10): 300 for Q(β^-), 30 for S(p)

Q-value: S(2n)=14291 13, S(2p)=6670 11 (2017Wa10)