Sur l'origine des alphas de scission

Abstract

On présente un mécanisme d'émission pour les particules α de scission à partir duquel le spectre énergétique, la fréquence d'apparition et leur variation en fonction de divers paramètres reçoivent une explication unitaire. On discute, en outre, de nouvelles possibilités d'études de la structure et de la dynamique du système fissionnant, au-delà du dernier point-seuil

The thermal-neutron-induced alpha-accompanied fission of235U investigation of the low energy part of the alpha spectrum

“…From the similarities between the characteristics of the c~-accompanied induced fission of 235U and the spontaneous fission of 252Cf, this very large difference in the number of emitted short-range a-particles is unexpected. As it has been pointed out by Cfirjan [9], both the shape of the c~-particle spectrum at low energy and the ratio R~ are crucial tests for any a-accompanied fission model, so that it is highly desirable to give an experimental answer to these open questions. For all these reasons, we found it justified to measure the low energy part of the c~-particle spectrum in the thermal-neutron-induced fission of 23sU using a different experimental technique.…”

The emission probabilities of long range alpha particles from even–even244–252Cm isotopes

“…In the cold valley, the minima is found for the fragment combinations with mass number A 1 = 4 He, 10 Be, 14 C, 16 C, 20 O, 22 O, 24 O, 26 Ne, 30 Mg, 32 Mg, 34 Si, 36 Si, 40 S, 42 S, 44 Ar, 46 Ar, 48 Ar, 50 Ca, 52 figure 4. The hatched bars belong to odd mass numbers and the dark ones belong to even mass numbers.…”

“…Carjan [48] suggests that LRA emission is possible only if the α cluster is formed inside the fissioning nucleus and should gain enough energy to overcome the Coulomb barrier of the scission nucleus.…”

Deformation effects in the alpha accompanied cold ternary fission of even-even 244-260Cf isotopes

“…Carjan suggests that the emission of long range alpha particle is possible only if alpha particle is formed inside the fissioning nucleus so as to attain sufficient energy to overcome the Coulomb barrier of the scissioning nucleus. Based on the theoretical model of Carjan [20], Serot and Wagemans [21] suggested that the characteristics of long range alpha particle strongly depends on the preformation probability of alpha particle formed in the ternary fission process and also on various parameters like fissility parameter Z 2 /A, alpha cluster preformation factor or spectroscopic factor S α and fission modes.…”

“…In addition to alpha particle, 10 Be and 14 C accompanied spontaneous ternary fission was also studied by Hamilton et al [17][18][19] using the Gammasphere technique for 252 Cf isotope. Based on the theoretical model of Carjan [20], the characteristics of long range alpha particles were studied in the spontaneous ternary fission of 244 Cm, 246 Cm, 248 Cm, 250 Cf, 252 Cf and even-even [238][239][240][241][242][243][244] Pu isotopes [21][22][23]. The emission probability and kinetic energy distribution of long range alpha particles were studied in detail for the corresponding isotopes of Cm, Pu and Cf, with the suitable ∆E-E telescope detectors at IRMM.…”