8 research outputs found
Recommended from our members
Identification of the New Isotope ^{244}Md.
In an experiment performed at Lawrence Berkeley National Laboratory's 88-inch cyclotron, the isotope ^{244}Md was produced in the ^{209}Bi(^{40}Ar,5n) reaction. Decay properties of ^{244}Md were measured at the focal plane of the Berkeley Gas-filled Separator, and the mass number assignment of A=244 was confirmed with the apparatus for the identification of nuclide A. The isotope ^{244}Md is reported to have one, possibly two, α-decaying states with α energies of 8.66(2) and 8.31(2) MeV and half-lives of 0.4_{-0.1}^{+0.4} and âŒ6ââs, respectively. Additionally, first evidence of the α decay of ^{236}Bk was observed and is reported
Recommended from our members
First Direct Measurements of Superheavy-Element Mass Numbers.
An experiment was performed at Lawrence Berkeley National Laboratory's 88-in. Cyclotron to determine the mass number of a superheavy element. The measurement resulted in the observation of two α-decay chains, produced via the ^{243}Am(^{48}Ca,xn)^{291-x}Mc reaction, that were separated by mass-to-charge ratio (A/q) and identified by the combined BGS+FIONA apparatus. One event occurred at A/q=284 and was assigned to ^{284}Nh (Z=113), the α-decay daughter of ^{288}Mc (Z=115), while the second occurred at A/q=288 and was assigned to ^{288}Mc. This experiment represents the first direct measurements of the mass numbers of superheavy elements, confirming previous (indirect) mass-number assignments
Recommended from our members
First Direct Measurements of Superheavy-Element Mass Numbers.
An experiment was performed at Lawrence Berkeley National Laboratory's 88-in. Cyclotron to determine the mass number of a superheavy element. The measurement resulted in the observation of two α-decay chains, produced via the ^{243}Am(^{48}Ca,xn)^{291-x}Mc reaction, that were separated by mass-to-charge ratio (A/q) and identified by the combined BGS+FIONA apparatus. One event occurred at A/q=284 and was assigned to ^{284}Nh (Z=113), the α-decay daughter of ^{288}Mc (Z=115), while the second occurred at A/q=288 and was assigned to ^{288}Mc. This experiment represents the first direct measurements of the mass numbers of superheavy elements, confirming previous (indirect) mass-number assignments
Recommended from our members
Decay spectroscopy of element 115 daughters: Rg 280 â Mt 276 and Mt 276 â Bh 272
Forty-six decay chains, assigned to the decay of 115288, were produced using the Am243(Ca48,3n)115288 reaction at the Lawrence Berkeley National Laboratory 88-in. cyclotron. The resulting series of α decays were studied using α-photon and α-x-ray spectroscopies. Multiple α-photon coincidences were observed in the element 115 decay chain members, particularly in the third- and fourth-generation decays (presumed to be Rg280 and Mt276, respectively). Upon combining these data with those from 22 115288 decay chains observed in a similar experiment, updated level schemes in Mt276 and Bh272 (populated by the α decay of Rg280 and Mt276, respectively) are proposed. Photons were observed in the energy range expected for K x rays coincident with the α decay of both Rg280 and Mt276. However, Compton scattering of higher-energy γ rays and discrete transitions are present in the K x-ray region preventing a definitive Z identification to be made based on observation of characteristic K x-ray energies
Recommended from our members
Decay and Fission Hindrance of Two- and Four-Quasiparticle K Isomers in ^{254}Rf.
Two isomers decaying by electromagnetic transitions with half-lives of 4.7(1.1) and 247(73) ÎŒs have been discovered in the heavy ^{254}Rf nucleus. The observation of the shorter-lived isomer was made possible by a novel application of a digital data acquisition system. The isomers were interpreted as the K^{Ï}=8^{-}, Îœ^{2}(7/2^{+}[624],9/2^{-}[734]) two-quasineutron and the K^{Ï}=16^{+}, 8^{-}Îœ^{2}(7/2^{+}[624],9/2^{-}[734])â8^{-}Ï^{2}(7/2^{-}[514],9/2^{+}[624]) four-quasiparticle configurations, respectively. Surprisingly, the lifetime of the two-quasiparticle isomer is more than 4 orders of magnitude shorter than what has been observed for analogous isomers in the lighter N=150 isotones. The four-quasiparticle isomer is longer lived than the ^{254}Rf ground state that decays exclusively by spontaneous fission with a half-life of 23.2(1.1) ÎŒs. The absence of sizable fission branches from either of the isomers implies unprecedented fission hindrance relative to the ground state
Recommended from our members
Publisher's Note: Decay and Fission Hindrance of Two- and Four-Quasiparticle K Isomers in (254)Rf [Phys. Rev. Lett. 115, 132502 (2015)].
Study of non-fusion products in the Ti-50+Cf-249 reaction
The isotopic distribution of nuclei produced in the 50Ti + 249Cf reaction has been studied at the gas-filled recoil separator TASCA at GSI Darmstadt, which separates ions according to differences in magnetic rigidity. The bombardment was performed at an energy around the Bass barrier and with the TASCA magnetic fields set for collecting fusion-evaporation reaction products. Fifty-three isotopes located ânorth-eastâ of 208Pb were identified as recoiling products formed in non-fusion channels of the reaction. These recoils were implanted with energies in two distinct ranges; besides one with higher energy, a significant low-energy contribution was identified. The latter observation was not expected to occur according to kinematics of the known types of reactions, namely quasi-elastic, multi-nucleon transfer, deep-inelastic collisions or quasifission. The present observations are discussed within the framework of two-body kinematics passing through the formation of a composite system.peerReviewe