Nobelium - By Hot Fusion

By Hot Fusion

232Th(26Mg,xn)258-xNo (x=4,5,6)

The cross sections for the 4-6n exit channels have been measured for this reaction at the FLNR.

238U(22Ne,xn)260-xNo (x=4,5,6)

This reaction was first studied in 1964 at the FLNR. The team were able to detect decays from 252Fm and 250Fm. The 252Fm activity was associated with an ~8 s half-life and assigned to 256102 from the 4n channel, with a yield of 45 nb. They were also able to detect a 10 s spontaneous fission activity also tentatively assigned to 256102. Further work in 1966 on the reaction examined the detection of 250Fm decay using chemical separation and a parent activity with a half-life of ~50 s was reported and correctly assigned to 254102. They also detected a 10 s spontaneous fission activity tentatively assigned to 256102. The reaction was used in 1969 to study some initial chemistry of nobelium at the FLNR. They determined eka-ytterbium properties, consistent with nobelium as the heavier homologue. In 1970, they were able to study the SF properties of 256No. In 2002, Patin et al. reported the synthesis of 256No from the 4n channel but were unable to detect 257No.

The cross section values for the 4-6n channels have also been studied at the FLNR.

238U(20Ne,xn)258-xNo

This reaction was studied in 1964 at the FLNR. No spontaneous fission activities were observed.

236U(22Ne,xn)258-xNo (x=4,5,6)

The cross sections for the 4-6n exit channels have been measured for this reaction at the FLNR.

235U(22Ne,xn)257-xNo (x=5)

This reaction was studied in 1970 at the FLNR. It was used to study the SF decay properties of 252No.

233U(22Ne,xn)255-xNo

The synthesis of neutron deficient nobelium isotopes was studied in 1975 at the FLNR. In their experiments they observed a 250 µs SF activity which they tentatively assigned to 250No in the 5n exit channel. Later results have not been able to confirm this activity and it is currently unidentified.

242Pu(18O,xn)260-xNo (x=4?)

This reaction was studied in 1966 at the FLNR. The team identified an 8.2 s SF activity tentatively assigned to 256102.

241Pu(16O,xn)257-xNo

This reaction was first studied in 1958 at the FLNR. The team measured ~8.8 MeV alpha particles with a half-life of 30 s and assigned to 253,252,251102. A repeat in 1960 produced 8.9 MeV alpha particles with a half-life of 2-40 s and assigned to 253102 from the 4n channel. Confidence in these results was later diminished.

239Pu(18O,xn)257-xNo (x=5)

This reaction was studied in 1970 at the FLNR in an effort to study the SF decay properties of 252No.

239Pu(16O,xn)255-xNo

This reaction was first studied in 1958 at the FLNR. The team were able to measure ~8.8 MeV alpha particles with a half-life of 30 s and assigned to253,252,251102. A repeat in 1960 was unsuccessful and it was concluded the first results were probably associated with background effects.

243Am(15N,xn)258-xNo (x=4)

This reaction was studied in 1966 at the FLNR. The team were able to detect 250Fm using chemical techniques and determined an associated half-lifesignificantly higher than the reported 3 s by Berkeley for the supposed parent 254No. Further work later the same year measured 8.1 MeV alpha particles with a half-life of 30-40 s.

243Am(14N,xn)257-xNo

This reaction was studied in 1966 at the FLNR. They were unable to detect the 8.1 MeV alpha particles detected when using a N-15 beam.

241Am(15N,xn)256-xNo (x=4)

The decay properties of 252No were examined in 1977 at Oak Ridge. The team calculated a half-life of 2.3 s and measured a 27% SF branching.

248Cm(18O,αxn)262-xNo (x=3)

The synthesis of the new isotope 259No was reported in 1973 from the LBNL using this reaction.

248Cm(13C,xn)261-xNo (x=3?,4,5)

This reaction was first studied in 1967 at the LBNL. The new isotopes 258No,257No and 256No were detected in the 3-5n channels. The reaction was repeated in 1970 to provide further decay data for 257No.

248Cm(12C,xn)260-xNo (4,5?)

This reaction was studied in 1967 at the LBNL in their seminal study of nobelium isotopes. The reaction was used in 1990 at the LBNL to study the SF of256No.

246Cm(13C,xn)259-xNo (4?,5?)

This reaction was studied in 1967 at the LBNL in their seminal study of nobelium isotopes.

246Cm(12C,xn)258-xNo (4,5)

This reaction was studied in 1958 by scientists at the LBNL using a 5% 246Cm curium target. They were able to measure 7.43 MeV decays from250Fm, associated with a 3 s 254No parent activity, resulting from the 4n channel. The 3 s activity was later reassigned to 252No, resulting from reaction with the predominant 244Cm component in the target. It could however not be proved that it was not due to the contaminant250mFm, unknown at the time. Later work in 1959 produced 8.3 MeV alpha particles with a half-life of 3 s and a 30% SF branch. This was initially assigned to 254No and later reassigned to 252No, resulting from reaction with the 244Cm component in the target. The reaction was restudied in 1967 and activities assigned to 254No and 253No were detected.

244Cm(13C,xn)257-xNo (x=4)

This reaction was first studied in 1957 at the Nobel Institute in Stockholm. The scientists detected 8.5 MeV alpha particles with a half-life of 10 minutes. The activity was assigned to 251No or 253No. The results were later dismissed as background. The reaction was repeated by scientists at the LBNL in 1958 but they were unable to confirm the 8.5 MeV alpha particles. The reaction was further studied in 1967 at the LBNL and an activity assigned to 253No was measured.

244Cm(12C,xn)256-xNo (x=4,5)

This reaction was studied in 1958 by scientists at the LBNL using a 95% 244Cm curium target. They were able to measure 7.43 MeV decays from250Fm, associated with a 3 s 254No parent activity, resulting from the reaction (246Cm,4n). The 3 s activity was later reassigned to252No, resulting from reaction (244Cm,4n). It could however not be proved that it was not due to the contaminant 250mFm, unknown at the time. Later work in 1959 produced 8.3 MeV alpha particles with a half-life of 3 s and a 30% SF branch. This was initially assigned to 254No and later reassigned to 252No, resulting from reaction with the 244Cm component in the target. The reaction was restudied in 1967 at the LBNL and an new activity assigned to 251No was measured.

252Cf(12C,αxn)260-xNo (x=3?)

This reaction was studied at the LBNL in 1961 as part of their search for element 104. They detected 8.2 MeV alpha particles with a half-life of 15 s. This activity was assigned to a Z=102 isotope. Later work suggests an assignment to 257No, resulting most likely from the α3n channel with the 252Cf component of the californium target.

252Cf(11B,pxn)262-xNo (x=5?)

This reaction was studied at the LBNL in 1961 as part of their search for element 103. They detected 8.2 MeV alpha particles with a half-life of 15 s. This activity was assigned to a Z=102 isotope. Later work suggests an assignment to 257No, resulting most likely from the p5n channel with the 252Cf component of the californium target.

249Cf(12C,αxn)257-xNo (x=2)

This reaction was first studied in 1970 at the LBNL in a study of 255No. It was studied in 1971 at the Oak Ridge Laboratory. They were able to measure coincident Z=100 K X-rays from 255No, confirming the discovery of the element.