Isotopes of nobelium
Encyclopedia
Nobelium
(No) is an artificial element, and thus a standard atomic mass
cannot be given. Like all artificial elements, it has no stable isotope
s. The first isotope
to be synthesized (and correctly identified) was 254No in 1966. There are 16 known radioisotopes which are 248No and 250No to 264No, and 3 isomer
s, 251mNo, 253mNo, and 254mNo. The longest-lived isotope is 259No with a half-life
of 58 minutes. The longest-lived isomer is 251mNo with a half-life of 1.7 seconds.
This cold fusion reaction was first studied in 1979 at the FLNR. Further work in 1988 at the GSI measured EC and SF branchings in 254No. In 1989, the FLNR used the reaction to measure SF decay characteristics for the two isomers of 254No. The measurement of the 2n excitation function was reported in 2001 by Yuri Oganessian
at the FLNR.
Patin et al. at the LBNL reported in 2002 the synthesis of 255-251No in the 1-4n exit channels and measured further decay data for these isotopes.
The reaction has recently been used at the Jyvaskylan Yliopisto Fysiikan Laitos (JYFL) using the RITU set-up to study K-isomerism in 254No. The scientists were able to measure two K-isomers with half-lives of 275 ms and 198 µs, respectively. They were assigned to 8- and 16+ K-isomeric levels.
The reaction was used in 2004-5 at the FLNR to study the spectroscopy of 255-253No. The team were able to confirm an isomeric level in 253No with a half-life
of 43.5 µs.
208Pb(44Ca,xn)252-xNo (x=2)
This reaction was studied in 2003 at the FLNR in a study of the spectroscopy of 250No.
207Pb(48Ca,xn)255-xNo (x=2)
The measurement of the 2n excitation function for this reaction was reported in 2001 by Yuri Oganessian and co-workers at the FLNR. The reaction was used in 2004-5 to study the spectroscopy of 253No.
206Pb(48Ca,xn)254-xNo (x=1,2,3,4)
The measurement of the 1-4n excitation functions for this reaction were reported in 2001 by Yuri Oganessian and co-workers at the FLNR.
The 2n channel was further studied by the GSI to provide a spectroscopic determination of K-isomerism in 252No. A K-isomer with spin
and parity
8- was detected with a half-life
of 110 ms.
204Pb(48Ca,xn)252-xNo (x=2)
The measurement of the 2n excitation function for this reaction was reported in 2001 by Yuri Oganessian at the FLNR. They reported a new isotope 250No with a half-life
of 36µs. The reaction was used in 2003 to study the spectroscopy of 250No.They were able to observe two spontaneous fission
activities with half-lives of 5.6µs and 54µs and assigned to 250No and 249No, respectively.
The latter activity was later assigned to a K-isomer in 250No. The reaction was reported in 2006 by Peterson et al. at the Argonne National Laboratory (ANL) in a study of SF in 250No. They detected two activities with half-lives of 3.7 µs and 43 µs and both assigned to 250No, the latter associated with a K-isomer.
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 to 253,252,251102. 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-life
significantly 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 of 256No.
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 from 250Fm, 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 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 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 from 250Fm, associated with a 3 s 254No parent activity, resulting from the reaction (246Cm,4n). The 3 s activity was later reassigned to 252No, 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.
Nobelium
Nobelium is a synthetic element with the symbol No and atomic number 102. It was first correctly identified in 1966 by scientists at the Flerov Laboratory of Nuclear Reactions in Dubna, Soviet Union...
(No) is an artificial element, and thus a standard atomic mass
Atomic mass
The atomic mass is the mass of a specific isotope, most often expressed in unified atomic mass units. The atomic mass is the total mass of protons, neutrons and electrons in a single atom....
cannot be given. Like all artificial elements, it has no stable isotope
Stable isotope
Stable isotopes are chemical isotopes that may or may not be radioactive, but if radioactive, have half-lives too long to be measured.Only 90 nuclides from the first 40 elements are energetically stable to any kind of decay save proton decay, in theory...
s. The first isotope
Isotope
Isotopes are variants of atoms of a particular chemical element, which have differing numbers of neutrons. Atoms of a particular element by definition must contain the same number of protons but may have a distinct number of neutrons which differs from atom to atom, without changing the designation...
to be synthesized (and correctly identified) was 254No in 1966. There are 16 known radioisotopes which are 248No and 250No to 264No, and 3 isomer
Nuclear isomer
A nuclear isomer is a metastable state of an atomic nucleus caused by the excitation of one or more of its nucleons . "Metastable" refers to the fact that these excited states have half-lives more than 100 to 1000 times the half-lives of the other possible excited nuclear states...
s, 251mNo, 253mNo, and 254mNo. The longest-lived isotope is 259No with a half-life
Half-life
Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
of 58 minutes. The longest-lived isomer is 251mNo with a half-life of 1.7 seconds.
Table
| nuclide symbol |
Z(p Proton The proton is a subatomic particle with the symbol or and a positive electric charge of 1 elementary charge. One or more protons are present in the nucleus of each atom, along with neutrons. The number of protons in each atom is its atomic number.... ) |
N(n Neutron The neutron is a subatomic hadron particle which has the symbol or , no net electric charge and a mass slightly larger than that of a proton. With the exception of hydrogen, nuclei of atoms consist of protons and neutrons, which are therefore collectively referred to as nucleons. The number of... ) |
isotopic mass (u) |
half-life | decay mode(s)Abbreviations: EC: Electron capture Electron capture Electron capture is a process in which a proton-rich nuclide absorbs an inner atomic electron and simultaneously emits a neutrino... IT: Isomeric transition Isomeric transition An isomeric transition is a radioactive decay process that involves emission of a gamma ray from an atom where the nucleus is in an excited metastable state, referred to in its excited state, as a nuclear isomer.... SF: Spontaneous fission Spontaneous fission Spontaneous fission is a form of radioactive decay characteristic of very heavy isotopes. Because the nuclear binding energy reaches a maximum at a nuclear mass greater than about 60 atomic mass units , spontaneous breakdown into smaller nuclei and single particles becomes possible at heavier masses... |
daughter isotope(s) |
nuclear spin |
|---|---|---|---|---|---|---|---|
| excitation energy | |||||||
| 250No | 102 | 148 | 250.08751(22)# | 5.7(8) µs | SF Spontaneous fission Spontaneous fission is a form of radioactive decay characteristic of very heavy isotopes. Because the nuclear binding energy reaches a maximum at a nuclear mass greater than about 60 atomic mass units , spontaneous breakdown into smaller nuclei and single particles becomes possible at heavier masses... (99.95%) |
(various) | 0+ |
| α Alpha decay Alpha decay is a type of radioactive decay in which an atomic nucleus emits an alpha particle and thereby transforms into an atom with a mass number 4 less and atomic number 2 less... (.05%) |
246Fm | ||||||
| β+ Beta decay In nuclear physics, beta decay is a type of radioactive decay in which a beta particle is emitted from an atom. There are two types of beta decay: beta minus and beta plus. In the case of beta decay that produces an electron emission, it is referred to as beta minus , while in the case of a... (2.5×10−4%) |
250Md | ||||||
| 251No | 102 | 149 | 251.08901(19)# | 0.78(2) s | α (89%) | 247Fm | 7/2+# |
| SF (10%) | (various) | ||||||
| β+ (1%) | 251Md | ||||||
| 251mNo | 110(180)# keV | 1.7(10) s | 9/2-# | ||||
| 252No | 102 | 150 | 252.088977(14) | 2.27(14) s | α (73.09%) | 248Fm | 0+ |
| SF (26.9%) | (various) | ||||||
| β+ (1%) | 252Md | ||||||
| 253NoNot directly synthesized, occurs as decay product Decay product In nuclear physics, a decay product is the remaining nuclide left over from radioactive decay. Radioactive decay often involves a sequence of steps... of 257Rf |
102 | 151 | 253.09068(11)# | 1.62(15) min | α (80%) | 249Fm | (9/2-)# |
| β+ (20%) | 253Md | ||||||
| SF (10−3%) | (various) | ||||||
| 253mNo | 129(19) keV | 31 µs | 5/2+# | ||||
| 254No | 102 | 152 | 254.090955(19) | 51(10) s | α (89.3%) | 250Fm | 0+ |
| β+ (10%) | 254Md | ||||||
| SF (.31%) | (various) | ||||||
| 254mNo | 500(100)# keV | 0.28(4) s | IT Isomeric transition An isomeric transition is a radioactive decay process that involves emission of a gamma ray from an atom where the nucleus is in an excited metastable state, referred to in its excited state, as a nuclear isomer.... (80%) |
254No | 0+ | ||
| α (20%) | 250Fm | ||||||
| 255No | 102 | 153 | 255.093241(11) | 3.1(2) min | α (61.4%) | 251Fm | (1/2+) |
| β+ (38.6%) | 255Md | ||||||
| 256No | 102 | 154 | 256.094283(8) | 2.91(5) s | α (99.44%) | 252Fm | 0+ |
| SF (.55%) | (various) | ||||||
| EC Electron capture Electron capture is a process in which a proton-rich nuclide absorbs an inner atomic electron and simultaneously emits a neutrino... (.01%) |
256Md | ||||||
| 257No | 102 | 155 | 257.096877(23) | 25(2) s | α (99%) | 253Fm | (7/2+) |
| β+ (1%) | 257Md | ||||||
| 258No | 102 | 156 | 258.09821(22)# | 1.2(2) ms | SF (99.99%) | (various) | 0+ |
| α (.01%) | 254Fm | ||||||
| β+β+ (rare) | 258Fm | ||||||
| 259No | 102 | 157 | 259.10103(11)# | 58(5) min | α (75%) | 255Fm | (9/2+)# |
| EC (25%) | 259Md | ||||||
| SF (10%) | (various) | ||||||
| 260No | 102 | 158 | 260.10264(22)# | 106(8) ms | SF | (various) | 0+ |
| 262NoNot directly synthesized, occurs as decay product Decay product In nuclear physics, a decay product is the remaining nuclide left over from radioactive decay. Radioactive decay often involves a sequence of steps... of 262Lr |
102 | 160 | 262.10730(48)# | ~5 ms | SF | (various) | 0+ |
History of synthesis of isotopes by cold fusion
208Pb(48Ca,xn)256-xNo (x=1,2,3,4)This cold fusion reaction was first studied in 1979 at the FLNR. Further work in 1988 at the GSI measured EC and SF branchings in 254No. In 1989, the FLNR used the reaction to measure SF decay characteristics for the two isomers of 254No. The measurement of the 2n excitation function was reported in 2001 by Yuri Oganessian
Yuri Oganessian
Yuri Oganessian is a Russian nuclear physicist of Armenian descent. He and his team discovered the heaviest elements in the Periodic Table ....
at the FLNR.
Patin et al. at the LBNL reported in 2002 the synthesis of 255-251No in the 1-4n exit channels and measured further decay data for these isotopes.
The reaction has recently been used at the Jyvaskylan Yliopisto Fysiikan Laitos (JYFL) using the RITU set-up to study K-isomerism in 254No. The scientists were able to measure two K-isomers with half-lives of 275 ms and 198 µs, respectively. They were assigned to 8- and 16+ K-isomeric levels.
The reaction was used in 2004-5 at the FLNR to study the spectroscopy of 255-253No. The team were able to confirm an isomeric level in 253No with a half-life
Half-life
Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
of 43.5 µs.
208Pb(44Ca,xn)252-xNo (x=2)
This reaction was studied in 2003 at the FLNR in a study of the spectroscopy of 250No.
207Pb(48Ca,xn)255-xNo (x=2)
The measurement of the 2n excitation function for this reaction was reported in 2001 by Yuri Oganessian and co-workers at the FLNR. The reaction was used in 2004-5 to study the spectroscopy of 253No.
206Pb(48Ca,xn)254-xNo (x=1,2,3,4)
The measurement of the 1-4n excitation functions for this reaction were reported in 2001 by Yuri Oganessian and co-workers at the FLNR.
The 2n channel was further studied by the GSI to provide a spectroscopic determination of K-isomerism in 252No. A K-isomer with spin
Spin (physics)
In quantum mechanics and particle physics, spin is a fundamental characteristic property of elementary particles, composite particles , and atomic nuclei.It is worth noting that the intrinsic property of subatomic particles called spin and discussed in this article, is related in some small ways,...
and parity
Parity (physics)
In physics, a parity transformation is the flip in the sign of one spatial coordinate. In three dimensions, it is also commonly described by the simultaneous flip in the sign of all three spatial coordinates:...
8- was detected with a half-life
Half-life
Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
of 110 ms.
204Pb(48Ca,xn)252-xNo (x=2)
The measurement of the 2n excitation function for this reaction was reported in 2001 by Yuri Oganessian at the FLNR. They reported a new isotope 250No with a half-life
Half-life
Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
of 36µs. The reaction was used in 2003 to study the spectroscopy of 250No.They were able to observe two spontaneous fission
Spontaneous fission
Spontaneous fission is a form of radioactive decay characteristic of very heavy isotopes. Because the nuclear binding energy reaches a maximum at a nuclear mass greater than about 60 atomic mass units , spontaneous breakdown into smaller nuclei and single particles becomes possible at heavier masses...
activities with half-lives of 5.6µs and 54µs and assigned to 250No and 249No, respectively.
The latter activity was later assigned to a K-isomer in 250No. The reaction was reported in 2006 by Peterson et al. at the Argonne National Laboratory (ANL) in a study of SF in 250No. They detected two activities with half-lives of 3.7 µs and 43 µs and both assigned to 250No, the latter associated with a K-isomer.
History of synthesis of isotopes 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
Half-life
Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
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
Spontaneous fission
Spontaneous fission is a form of radioactive decay characteristic of very heavy isotopes. Because the nuclear binding energy reaches a maximum at a nuclear mass greater than about 60 atomic mass units , spontaneous breakdown into smaller nuclei and single particles becomes possible at heavier masses...
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
Half-life
Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
of ~50 s was reported and correctly assigned to 254102. They also detected a 10 s spontaneous fission
Spontaneous fission
Spontaneous fission is a form of radioactive decay characteristic of very heavy isotopes. Because the nuclear binding energy reaches a maximum at a nuclear mass greater than about 60 atomic mass units , spontaneous breakdown into smaller nuclei and single particles becomes possible at heavier masses...
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
Spontaneous fission
Spontaneous fission is a form of radioactive decay characteristic of very heavy isotopes. Because the nuclear binding energy reaches a maximum at a nuclear mass greater than about 60 atomic mass units , spontaneous breakdown into smaller nuclei and single particles becomes possible at heavier masses...
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
Half-life
Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
of 30 s and assigned to 253,252,251102. A repeat in 1960 produced 8.9 MeV alpha particles with a half-life
Half-life
Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
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
Half-life
Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
of 30 s and assigned to 253,252,251102. 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-life
Half-life
Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
significantly 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
Half-life
Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
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
Half-life
Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
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 of 256No.
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
Curium
Curium is a synthetic chemical element with the symbol Cm and atomic number 96. This radioactive transuranic element of the actinide series was named after Marie Skłodowska-Curie and her husband Pierre Curie. Curium was first intentionally produced and identified in summer 1944 by the group of...
target. They were able to measure 7.43 MeV decays from 250Fm, 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 contaminant 250mFm, unknown at the time.
Later work in 1959 produced 8.3 MeV alpha particles with a half-life
Half-life
Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
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
Half-life
Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
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
Curium
Curium is a synthetic chemical element with the symbol Cm and atomic number 96. This radioactive transuranic element of the actinide series was named after Marie Skłodowska-Curie and her husband Pierre Curie. Curium was first intentionally produced and identified in summer 1944 by the group of...
target. They were able to measure 7.43 MeV decays from 250Fm, associated with a 3 s 254No parent activity, resulting from the reaction (246Cm,4n). The 3 s activity was later reassigned to 252No, 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
Half-life
Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
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
Half-life
Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
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
Californium
Californium is a radioactive metallic chemical element with the symbol Cf and atomic number 98. The element was first made in the laboratory in 1950 by bombarding curium with alpha particles at the University of California, Berkeley. It is the ninth member of the actinide series and was the...
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
Half-life
Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
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
Californium
Californium is a radioactive metallic chemical element with the symbol Cf and atomic number 98. The element was first made in the laboratory in 1950 by bombarding curium with alpha particles at the University of California, Berkeley. It is the ninth member of the actinide series and was the...
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.