Experimental detection of superdeformed nuclear shapes in the mass range A approx.= 150 and angular momentum range I > 70 h by measurement of the light charged particles emitted before fission
Description
In the asymmetric systems 350 MeV 35Cl + Ag and 254 MeV 37Cl + 124Sn the angular and energy distributions of the protons and alpha particles were measured in coincidence with fission fragments. Beside the particle emission of the fragments also a comparably strong emission (Msub(α) approx.= 0.13) from the compound nucleus system (A = 161) was observed which could be separated by analysis of the spectrum shape because of the efficient detection of the fission fragments (ΔΩ approx.= 1.4 sr) and a large number of correlation angles. From the observation of a nuclear shadow effect of the fragments the lifetime of the compound system is estimated to tau approx.= (1.3 - 2.6) x 10-20 s in well agreement with calculations of Gregoire et al. on the proceeding of the ''fast fission''. Hints on a strong deformation of the compound nucleus system give the energy differential (''subbarrier'' emission) and integral angular correlations beyond the reaction plane related to the spin direction of the fissioning system. By means of a semiclassical model of Dossing from the measured anisotropy of the protons and alpha particles under simplifying assumptions concerning the transmission coefficients in the medium and upper angular momentum window of the fission (I approx.= 87 (h/2π), respectively I approx.= 100 (h/2π)) values of the deformation parameters of vertical strokedeltavertical stroke approx.= 0.6, respectively vertical strokedeltavertical stroke approx.= 0.8 were determined which corresponds to the axis ratio of an ellipsoid of a/b approx.= 2.1 to 2.7. Relating to an experiment in the Heidelberg crystal ball on the same reaction (37Cl + 124Sn) at 200 MeV incident energy the onset of the superbackbending is discussed. (orig.)
Availability note (English)
MF available from INIS under the Report Number.Abstract (German)
An den asymmetrischen Systemen 350 MeV 35Cl + Ag und 254 MeV 37Cl + 124Sn wurden die Winkel- und Energieverteilungen der Protonen und Alphateilchen in Koinzidenz mit Spaltfragmenten gemessen. Neben der Teilchenemission von den Fragmenten wurde auch eine vergleichbar starke Emission (Msub(α) approx.= 0.13) vom vereinigten Kernsystem (A = 161) beobachtet, die aufgrund des effizienten Nachweises der Spaltfragmente (ΔΩ approx.= 1.4 sr) und einer grossen Anzahl von Korrelationswinkeln durch Analyse der Spektrenform abgetrennt werden konnte. Aus der Beobachtung eines nuklearen Schatteneffekts der Fragmente wird die Lebensdauer des vereinigten Systems zu tau approx.= (1.3 - 2.6) x 10-20 s abgeschaetzt, in guter Uebereinstimmung mit Rechnungen von Gregoire et al. zum Ablauf der ''Schnellen Spaltung''. Hinweise auf eine starke Deformation des vereinigten Kernsystems geben die energiedifferentiellen (''Subbarrier'' Emission) und - integralen Winkelkorrelationen ausserhalb der Reaktionsebene, bezueglich der Spinrichtung des spaltenden Systems. Mit Hilfe eines semiklassischen Modells von Dossing werden aus den gemessenen Anisotropien der Protonen und Alphateilchen unter vereinfachenden Annahmen bezueglich der Transmissionskoeffizienten im mittleren und oberen Drehimpulsfenster der Spaltung (I approx.= 87 (h/2π), bzw. I approx.= (h/2π)) Werte des Deformationsparameters von vertical strokedeltavertical stroke approx.= 0.6, bzw. vertical strokedeltavertical stroke approx.= 0.8 ermittelt, was dem Achsenverhaeltnis eines Ellipsoids von a/b approx.= 2.1 bis 2.7 entspricht. In bezug auf ein Experiment in der Heidelberger Kristallkugel an derselben Reaktion (37Cl + 124Sn) bei 200 MeV Einschussenergie wird das Einsetzen des ''Superbackbendings'' diskutiert. (orig.)
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Additional details
Additional titles
- Original title (German)
- Experimenteller Nachweis superdeformierter Kernformen im Massenbereich A approx.= 150 und Drehimpulsbereich I > 70 h durch Messung der vor Spaltung emittierten leichten geladenen Teilchen
Publishing Information
- Imprint Pagination
- 84 p.
- Report number
- INIS-mf--9221
INIS
- Country of Publication
- Germany
- Country of Input or Organization
- Germany
- INIS RN
- 15071670
- Subject category
- S73: NUCLEAR PHYSICS AND RADIATION PHYSICS;
- Resource subtype / Literary indicator
- Numerical Data, Thesis
- Descriptors DEI
- ALPHA DECAY; ALPHA PARTICLES; ALPHA SPECTRA; ANGULAR CORRELATION; ANGULAR DISTRIBUTION; ANISOTROPY; BACKBENDING; CHLORINE 35 REACTIONS; CHLORINE 37 REACTIONS; COMPOUND NUCLEI; COMPOUND-NUCLEUS REACTIONS; ENERGY SPECTRA; EXPERIMENTAL DATA; FISSION FRAGMENTS; GADOLINIUM 143; HIGH SPIN STATES; HOLMIUM 161; LIFETIME; MASS SPECTRA; MEV RANGE 100-1000; NUCLEAR DEFORMATION; PROTON SPECTRA; PROTONS; QUASI-FISSION; RESONANCE; ROTATIONAL STATES; SEMICLASSICAL APPROXIMATION; SILVER 107 TARGET; SILVER 109 TARGET; TIN 124 TARGET
- Descriptors DEC
- BARYONS; BETA DECAY RADIOISOTOPES; BETA-PLUS DECAY RADIOISOTOPES; CATIONS; CHARGED PARTICLES; CORRELATIONS; DATA; DECAY; DEFORMATION; DISTRIBUTION; ELECTRON CAPTURE RADIOISOTOPES; ELEMENTARY PARTICLES; ENERGY LEVELS; ENERGY RANGE; EVEN-ODD NUCLEI; EXCITED STATES; FERMIONS; GADOLINIUM ISOTOPES; HADRONS; HEAVY ION REACTIONS; HELIUM IONS; HOLMIUM ISOTOPES; HOURS LIVING RADIOISOTOPES; HYDROGEN IONS; HYDROGEN IONS 1 PLUS; INFORMATION; INTERMEDIATE MASS NUCLEI; IONS; ISOTOPES; MEV RANGE; NUCLEAR DECAY; NUCLEAR FRAGMENTS; NUCLEAR REACTIONS; NUCLEI; NUCLEONS; NUMERICAL DATA; ODD-EVEN NUCLEI; RADIOISOTOPES; RARE EARTH NUCLEI; SPECTRA; TARGETS