Average multipolarity of continuum transitions in nuclei at high angular momentum

Feenstra, S.J.; Klinken, J. van; J.P., Pijn,; Janssens, R. V. F.; Michel, C.; Steyaert, J.; Vervier, J.; Cornelis, K.; Huyse, M.; Lhersonneau, G.

doi:10.1016/0370-2693(79)90193-x

Cited by 30 publications

(8 citation statements)

References 7 publications

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“…This has been found in several other cases (Simon et a1 1979, Newton et al 1978, Ockels l978a, Deleplanque et al 1978aa1though there is at least one example (Trautmann et al 1975) which seems to differ. conflicting results (Westerberg et al 1978, Feenstra et al 1979.…”

Section: Statistical Gamma Raysmentioning

confidence: 99%

Nuclei at High Angular Momentum

Diamond¹,

Stephens²

1980

Annu. Rev. Nucl. Part. Sci.

105

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Section: Statistical Gamma Raysmentioning

confidence: 99%

Nuclei at High Angular Momentum

Diamond¹,

Stephens²

1980

Annu. Rev. Nucl. Part. Sci.

105

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“…Most nuclear-structure information for very high-spin states is obtained from the study of the y-ray multiplicity, 1 angular correlations, 2 electron conversions, 3 and Doppler shifts 4 in the y-ray continuum spectra. Such data have given information about moments of inertia, transition multipolarities, and level lifetimes as functions of spin for a variety of nuclei.…”

Section: Transition-energy Correlations In the Y-ray Continuum-a New mentioning

confidence: 99%

Transition-Energy Correlations in theγ-Ray Continuum—A New Approach

et al. 1979

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A new method, which has been developed to isolate energy-correlated cascades from a background of uncorrelated events in the y-ray continuum, has been applied to the le O + 64 Ni reaction at £( 16 0) «80 MeV. In 74 Se, the dominant reaction product, it gives 28/% 2 ^53 ±5 and 65 ±6 MeV' 1 , respectively, for the rotationallike cascades below and above a phase transition observed at 7^22 units. These data also indicate that only a small portion of the decay proceeds through rotationallike cascades.Most nuclear-structure information for very high-spin states is obtained from the study of the y-ray multiplicity, 1 angular correlations, 2 electron conversions, 3 and Doppler shifts 4 in the y-ray continuum spectra. Such data have given information about moments of inertia, transition multipolarities, and level lifetimes as functions of spin for a variety of nuclei. From such studies phase changes have been observed between different nuclear shapes. In general, these data are consistent with the hypothesis that the highspin states decay predominantly by collective rotational cascades of stretched quadrupole transitions through bands which are essentially parallel to a rigid-rotor yrast line. An exponentially decreasing tail in these spectra, corresponding to 2-4 transitions per cascade, is found to be statistical in nature. Also, for more nearly spherical nuclei a low-energy bump of mostly stretched dipole transitions is found 2 to be uncorrelated with respect to multiplicity and transition energy.The present Letter reports a new method developed to isolate correlated rotational cascades from the background of uncorrelated events. This approach, which has been applied to the reaction 64 Ni + 16 O-80 Kr*, for the first time allows a study of the detailed energy correlations in the continuum spectrum. A target of 600-M^/cm 2 64 Ni was bombarded with 80-MeV le O ions from the Niels Bohr Institute's model FN tandem accelerator. The most probable (~75%) exit channel for this reaction is (a2n) 0 The maximum angular momentum, Z max , of the resulting 74 Se system has been determined to be ^ 30 units, from y-multiplicity studies. 5 The ground-state band of this nucleus has been studied previously 5 and shows a transition at spin lQfc from a vibrationallike to a rotationallike structure. The coexistence of these configurations has been discussed recently. 6 The experimental setup consisted of four 12.7-cm-diamxl5.2-cm Nal(Tl) transition-energy detectors each with a lead shield and a collimator of 7.3 cm diam to ensure the best possible photopeak-to-total ratio (46% for 60 Co) for the detection of the transition-energy spectrum. A resolution of 7.0-8.5% was obtained,, Three of the detectors were placed in the horizontal plane at 90° and ± 150° with respect to the beam direction and the fourth was at 90° below the plane. In addition an in-plane multiplicity filter of two 7-cmdiamx 7-cm Nal(Tl) counters placed at ± 40° and a 5-cm-diamxl5-cm Nal(Tl) counter placed at 0° was used. The multiplicity counters were located as close to t...

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“…The data were analyzed as described in [5]. We will not discuss the high energy region above the bump because here our restriction to stretched transitions is not a good assumption (there is probably an appreciable amount of nonstretched E1 transitions present in the spectrum [7,8]; as was mentioned above L = 1, A 1 = 0 transitions cannot be distinguished from L = 2, A1=2 transitions in the angular correlation experiments [5]). For the ~S~ compound system there is ~801~J(, quadrupole radiation in the bump at ~ 1.5 MeV; at lower energies, however, the dipole transitions become more prominent, even dominant (85 o/i; L = 1 at 0.5 MeV).…”

Section: Experimental Results and Data Analysismentioning

confidence: 99%

“…Recently several studies have concentrated on the shape [1][2][3], the multiplicity [3,4], the angular correlations [5,6], the conversion coefficients [7][8][9], the average lifetimes [10] and the transition energy correlations [11] of continuum 7rays. This is in contradiction to the results obtained by Feenstra et al [7,8] from conversion electron measurements in (7, xn) and (ZONe, xn) reactions. At energies below the E2-bump there appears a dipole component which varies in intensity depending on the properties of the particular compound system.…”

Section: Introductionmentioning

confidence: 99%

Linear polarization and angular correlation of continuumγ-rays

et al. 1980

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The linear polarization and angular correlation of continuum ?,-rays have been measured for the reactions 124Sn(4~ x rt) 164-xEr and 11opd(4OAr ' xn) t5o XGd" From the angular correlation experiments we find that the dominant fractions of the radiation are stretched quadrupoles (50-80%) and stretched dipoles. The linear polarization results are compatible with mainly M1 multipolarity for the dipole part of the continuum in the energy range between 0.5 and 1.6 MeV.

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Average multipolarity of continuum transitions in nuclei at high angular momentum

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Cited by 30 publications

References 7 publications

Nuclei at High Angular Momentum

Nuclei at High Angular Momentum

Transition-Energy Correlations in theγ-Ray Continuum—A New Approach

Linear polarization and angular correlation of continuumγ-rays

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