Synthesis of isotopes of fermium with mass numbers 247 and 246

Флеров, Г.Н.; Polikanov, S.M.; Mikheev, V.L.; Ilyushchenko, V.I.; Miller, M.; Shchegolev, V.A.

doi:10.1007/bf01175203

Cited by 21 publications

(4 citation statements)

References 1 publication

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“…This suggestion is supported by the observation of the chain 8722 keV → 8471 keV → 8126 keV, since an α -activity of E α = 8.18±0.03 MeV and T 1/2 = 9.2±2.3 s, observed in the reaction 12 C + 239 Pu at E lab = 74 MeV, was assigned to 247m Fm by Flerov at al. [24]. With respect to possible inaccuracies in the energy calibration and the deviation of our single event from the mean value an agreement is likely.…”

Section: Isotope 255 104mentioning

confidence: 90%

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Spontaneous fission and alpha-decay properties of neutron deficient isotopes 257−253104 and 258106

Heßberger

Hofmann

Ninov

et al. 1997

Z Phys A - Particles and Fields

134

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Spontaneous fission and α-decay of 253−257 104 and 258 106 were investigated in irradiations of 204,206,208 Pb with 50 Ti and 209 Bi with 51 V, respectively. New spontaneous fission activities were identified and assigned to 253 104, 254 104, and 258 106. The half-lives were measured as T 1/2 = (48 +17 −10 ) µs for 253 104, T 1/2 = (23 ± 3) µs for 254 104, and T 1/2 = (2.9 +1.3 −0.7 ) ms for 258 106. No indication for α-decay of any of these isotopes was found. For the α-decay branching ratios b α limits corresponding to b α ≤ 0.1 for 253 104, b α ≤ 0.015 for 254 104, and b α ≤ 0.2 for 258 106 were obtained. These results prove a reduced fission probability for nuclei with neutron numbers N=152 up to Z=106 and a steep decrease of the fission halflives for neutron numbers N < 152 up to element 104.α-decay data of 257 104 and 255 104 have been improved. An isomeric state decaying by α-emission was identified in 257 104 and attributed to a low lying 11/2 − [725] state. A small α-decay branch for the even -even nucleus 256 104, indicated in an earlier experiment at SHIP, was confirmed, allowing a better founded extrapolation of experimental masses for even -even nuclei up to 264 Hs (Z=108), the heaviest even -even nucleus identified so far.

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Section: Isotope 255 104mentioning

confidence: 90%

“…While the events above 8.7 MeV could predominantly be assigned to 255 104, those at 8. 6-8.7 MeV are attributed mainly to 251 No and those at 7.8-8.2 MeV to the granddaughter 247 Fm [24]; the broad distribution of the latter events is probably caused by energy summing between α -particles and conversion electrons [25].…”

Section: Isotope 255 104mentioning

confidence: 99%

Spontaneous fission and alpha-decay properties of neutron deficient isotopes 257−253104 and 258106

Heßberger

Hofmann

Ninov

et al. 1997

Z Phys A - Particles and Fields

134

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“…In 1967, Flerov et al identified 247 Fm in the paper "Synthesis of isotopes of fermium with mass numbers 247 and 246" [31]. A 239 Pu target was bombarded with 72−74 MeV 12 C from the Dubna 310-cm heavy-ion cyclotron and 247 Fm was formed in (4n) fusion-evaporation reactions.…”

Section: Fmmentioning

confidence: 99%

Discovery of isotopes with Z≤10

Thoennessen

2012

Atomic Data and Nuclear Data Tables

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“…2.6.6 Einsteinium, fermium isotopes.-The synthesis of several new isotopes of einsteinium and fermium and the measurement of additional radio active properties of other isotopes of these elements have been accomplished by investigators in the USA (117,121,122,(130)(131)(132)(133)(134) and in the USSR (135,136) as shown in Table IV. 2.6.7 Short-lived spontaneous fission isotopes of fermium.-Hulet et al (134) of the Lawrence Radiation Laboratory at Livermore have attempted, without success, to observe the formation of 268Fm by neutron irradiation of !li7Fm in the ultra-high flux of a Savannah River reactor, which indicates that this much sought-after isotope has a T1/2< 5 sec if formed with a I-barn cross section. Also of interest are : the recent observation that 246Fm, nomi nally a 1.2-sec alpha-particle emitter, also decays by spontaneous fission, the ratio of spontaneous fission events to alpha-decay events being about 0.08 (130) ; the observation that 248Fm decays by spontaneous fission (0.…”

Section: Other Work On Transuranium Elementsmentioning

confidence: 98%