Reinvestigation of the gamma branch from the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi mathvariant="normal">U</mml:mi></mml:mrow><mml:mprescripts /><mml:mrow /><mml:mrow><mml:mn>238</mml:mn></mml:mrow><mml:mrow /><mml:mrow /></mml:mmultiscripts></mml:mrow></mml:math>shape isomer

Kantele, J.; Stöffl, W.; Ussery, L.E.; Decman, D.J.; Henry, E. A.; Estep, R.J.; Hoff, R. W.; Mann, L.G.

doi:10.1103/physrevc.29.1693

Cited by 23 publications

(9 citation statements)

References 14 publications

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“…One of the persisting problems associated with fission shape isomers is the interesting question of competing decay modes of shape isomers such as, for example, decay by -ray emission. This process has been observed [10] and extensively investigated in the 1980s and 1990s in 238 U [11,12] and 236 U [13]. Particularly in the latter case this decay mode dominates over isomeric fission.…”

mentioning

confidence: 83%

Identification of a Shape Isomer inU235

Oberstedt

Oberstedt²,

Gawrys

et al. 2007

Phys. Rev. Lett.

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The shape isomer in 235U has been searched for in a neutron-induced fission experiment on 234U, which was performed at the isomer spectrometer NEPTUNE of the EC-JRC IRMM. A neutron source, with a tunable pulse frequency in the Hz to kHz range and its individually adjustable neutron pulse width in connection with an appropriate detector system turned out to be the ideal instrument to perform an isomer search, when decay half-lives above 100 micros are expected. From the delayed fission events observed for two different NEPTUNE settings and at mean incident neutron energies En=0.95 and 1.27 MeV the isomeric fission half-life could be determined to be T1/2=(3.6+/-1.8) ms. The corresponding cross section was determined to sigmaif=(10+/-8) microb. With these results an experimental confirmation for the existence of a superdeformed shape isomer in odd-uranium isotopes is given for the first time.

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mentioning

confidence: 83%

Identification of a Shape Isomer inU235

Oberstedt

Oberstedt²,

Gawrys

et al. 2007

Phys. Rev. Lett.

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“…However, in another measurement Kantele etal. [16] observed a gamma-ray line at (2512.7_ 0.5) keV with a cross section of (42___ 12) gbarn in the 18 MeV d+ 238U reaction, but could not confirm the 1.879 MeV E1 gamma transition because of unsufficient experimental sensitivity, The half-life of the 2.513 MeV gamma transition could not be extracted.…”

Section: Introductionmentioning

confidence: 78%

“…In Table 2 the cross sections for the 2.513 MeV and the 1.878 MeV gamma transition depopulating the shape isomeric state in 238U determined in that way are compared with the results of Russo et al [4] and Kantele et al [15,16].…”

Section: Gamma-back Decay Of the 23sv Fission Isomermentioning

confidence: 97%

“…the most prominent delayed gamma ray of a fission product within the time region of interest is from the 1.2798 MeV transition in ~a4mTe with a half-life of 164 ns and a cross section of (16+_3)mbarn [16]. The almost complete absence (48 +_ 35 counts) of this gamma-ray line in our spectrum proves the excellent suppression of gamma rays from isomers in fission products and rules out in an unambiguous way the possibility that the observed gamma-ray lines at 2.513 MeV and 1.878 MeV are due to a fission product.…”

Section: Gamma-back Decay Of 23smumentioning

confidence: 99%

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Fission and gamma-ray decay of the238U shape isomer

Steinmayer

Löbner

Corradi

et al. 1992

Z. Physik A - Hadrons and Nuclei

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The decay of the 238U superdeformed shape isomer has been reinvestigated by detecting for the first time simultaneously the fission and the gamma-back decay. An electrostatic deflection system has been used to transport the 238mu recoils, produced in a 238U(d, pn) reaction with a pulsed beam of 18 MeV deuterons, in front of a detector set-up consisting of three ion-implanted solidstate detectors and a Ge(Li) gamma-detector. The gamma-back decay has been measured in coincidence with conversion electrons of the 2 + ~ 0 + transition deexciting the first rotational state in 238U. Two gamma-transitions of 2.513 MeV and 1.878 MeV have been observed with half-lives consistent with the result obtained for the decay by delayed fission T1;2 =(298 _+ 18) ns. PACS" 23.20.Ck; 23.20.Lv; 25.85.Ge; 27.90. + b

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“…One of the persisting problems associated with fission isomers is the interesting question of competing decay modes as for example decay by γ-ray emission, which has been studied thoroughly in the 1980s and 1990s in 240 Pu [5], 238 U [6] and 236 U [7]. Even more intriguing today is the lack of any shape-isomer half-life data for odd-N uranium and neptunium isotopes.…”

Section: Introductionmentioning

confidence: 99%

Research on isomer decay with the NEPTUNE spectrometer

Oberstedt¹,

Plompen²,

Semkova³

et al. 2007

Nd2007

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Abstract.A new spectrometer has been built at the EC-JRC IRMM to investigate isomer decay in the millisecond range and activation cross sections of isotopes, where isomeric states exist and are populated. The spectrometer is equipped with high-resolution gamma-ray detectors and an ionisation chamber for the measurement of charged particles, e.g., fission fragments. NEPTUNE provides pulsed quasi mono-energetic neutrons at pulse repetition frequencies up to 5 kHz and tuneable neutron pulse widths ranging from 10 µs into the ms-region. For this purpose a beam chopper based on a parallel-plate capacitor has been integrated into the accelerator beam line in order to deflect the charged-particle beam onto a tantalum beam dump. First research has been performed with the NEPTUNE spectrometer dedicated to the shape isomer search in the odd-A uranium isotopes 235 U, 237 U and 239 U. In further experiments the population of long-lived spin isomers was investigated.

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Reinvestigation of the gamma branch from theU238shape isomer

Cited by 23 publications

References 14 publications

Identification of a Shape Isomer inU235

Identification of a Shape Isomer inU235

Fission and gamma-ray decay of the238U shape isomer

Research on isomer decay with the NEPTUNE spectrometer

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