Search results for "Nuclear isomer"
showing 7 items of 17 documents
Aufbau eines automatisch arbeitenden ??2-Spektrometers und Untersuchung des Konversionslinienspektrums von In114m und ThB mit Folgeprodukten
1963
An automatically operatedπ√2 spectrometer is described. The regulated current supply is transistorized. With this spectrometer the electron spectra of In114m and of ThB with daughter products have been investigated. TheK/L ratio of the 191 keV isomeric transition in In114m was found to be 1·25±0·03, in excellent agreement with the theoretical value ofSliv andBand. In the electron spectrum of ThB and daughter products 46 lines were found betweenBϱ=1750Г cm andBϱ=10000Г cm. Some of them are new. Most important is a new weak line atBϱ=7030Г cm which fixes a new level atE=1·807 MeV in ThC′ (Po212). Simultaneously the earlier reported discrepancy between electron andγ-ray intensities for 1·8 MeV…
Identification of a millisecond isomeric state inCd81129via the detection of internal conversion and Compton electrons
2014
Abstract The decay of an isomeric state in the neutron-rich nucleus 129 Cd has been observed via the detection of internal conversion and Compton electrons providing first experimental information on excited states in this nucleus. The isomer was populated in the projectile fission of a 238 U beam at the Radioactive Isotope Beam Factory at RIKEN. From the measured yields of γ -rays and internal conversion electrons, a multipolarity of E 3 was tentatively assigned to the isomeric transition. A half-life of T 1 / 2 = 3.6 ( 2 ) ms was determined for the new state which was assigned a spin of ( 21 / 2 + ) , based on a comparison to shell model calculations performed using state-of-the-art reali…
Persistence of the Z=28 shell gap in A=75 isobars: Identification of a possible (1/2−) μs isomer in Co75 and β decay to Ni75
2021
Background: The evolution of shell structure around doubly-magic exotic nuclei is of great interest in nuclear physics and astrophysics. In the `south-west' region of $^{78}$Ni, the development of deformation might trigger a major shift in our understanding of explosive nucleosynthesis. To this end, new spectroscopic information on key close-lying nuclei is very valuable. Purpose: We intend to measure the isomeric and $\beta$ decay of $^{75}$Co, with one proton- and two neutron-holes relative to $^{78}$Ni, to access new nuclear structure information in $^{75}$Co and its $\beta$-decay daughters $^{75}$Ni and $^{74}$Ni. Methods: The nucleus $^{75}$Co is produced in relativistic in-flight fiss…
Alternative approach to populate and study the $^{229}Th$ nuclear clock isomer
2019
A new approach to observe the radiative decay of the $^{229}$Th nuclear isomer, and to determine its energy and radiative lifetime, is presented. Situated at a uniquely low excitation energy, this nuclear state might be a key ingredient for the development of a nuclear clock, a nuclear laser and the search for time variations of the fundamental constants. The isomer's $\gamma$ decay towards the ground state will be studied with a high-resolution VUV spectrometer after its production by the $\beta$ decay of $^{229}$Ac. The novel production method presents a number of advantages asserting its competitive nature with respect to the commonly used $^{233}$U $\alpha$-decay recoil source. In this …
Decay and Fission Hindrance of Two- and Four-Quasiparticle K Isomers in 254Rf
2015
International audience; Two isomers decaying by electromagnetic transitions with half-lives of 4.7(1.1) and 247(73) mu s 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-pi = 8(-), nu(2)(7/2(+)[624]; 9/2(-)[734]) two-quasineutron and the K-pi = 16(+), 8(-)nu(2)(7/2(+)[624]; 9/2(-)[734] circle times 8(-)pi(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 isomer…
Identification of a dipole band above the Iπ = 31/2- isomeric state in 189Pb
2015
A dipole band of six transitions built upon a firmly established I π = 31/2− isomeric state has been identified in 189Pb using recoil-isomer tagging. This is the lightest odd-mass Pb nucleus in which a dipole band is known. The dipole nature of the new transitions has been confirmed through angular-intensity arguments. The evolution of the excitation energy and the aligned-angular momentum of the states in the new dipole band are compared with those of dipole bands in heavier, odd-mass lead isotopes. This comparison suggests that the new band in 189Pb is based upon a π[s−2 1/2h9/2i13/2]11− ⊗ ν[i −1 13/2+ ]13/2+ configuration. However, the increased aligned-angular momentum in 189Pb may sugg…
Studying Gamow-Teller transitions and the assignment of isomeric and ground states at $N=50$
2022
Direct mass measurements of neutron-deficient nuclides around the N=50 shell closure below $^{100}$Sn were performed at the FRS Ion Catcher (FRS-IC) at GSI, Germany. The nuclei were produced by projectile fragmentation of $^{124}$Xe, separated in the fragment separator FRS and delivered to the FRS-IC. The masses of 14 ground states and two isomers were measured with relative mass uncertainties down to 1×10−7 using the multiple-reflection time-of-flight mass spectrometer of the FRS-IC, including the first direct mass measurements of $^{98}$Cd and $^{97}$Rh. A new QEC=5437±67 keV was obtained for $^{98}$Cd, resulting in a summed Gamow-Teller (GT) strength for the five observed transitions (0+…