A. S. Mondal

Molecular versus squared Woods–Saxon α-nucleus potentials in the 27Al(α, t)28Si reaction

The differential cross-section of the 27Al(α, t)28Si reaction for 64.5 MeV incident energy has been reanalysed in DWBA with full finite range using a squared Woods–Saxon (Michel) α-nucleus potential with the modified value of the depth parameter α = 2.0 as reported in a comment article by Michel and Reidemeister. This new value produces significant improvement in fitting the data of the reaction with its overall performance, in some cases, close to that previously observed for the molecular potential. Although the non-monotonic shallow molecular potential with a soft repulsive core and the Michel potentials produce the same quality fits to the elastic scattering and non-elastic processes, they are not phase equivalent. The two types of potential produce altogether different cross-sections, particularly at large reaction angles. The importance of the experimental cross-sections at large angles for both elastic scattering and non-elastic processes is elucidated.

A probable example of a nonmesonic double hypernucleus

SummaryA search is made to identify hypernuclear species with two or more decay centres in nuclear emulsion exposed to a separated beam of 3.0 GeV/c K−-mesons at the CERN Proton Synchrotron. In a sample of 493 hypernuclei one event has been observed whose most probable interpretation turns out to be31SiΛΛ with the successive decay modes and binding energyBΛΛ=(38.2±6.3) MeV.RiassuntoSi è fatta una ricerca per identificare le specie ipernucleari con due o più centri di decadimento in un’emulsione nucleare esposta ad un fascio separato di mesoni K− di 3.0 GeV/c al proto-sincrotrone del CERN. In un campione di 493 ipernuclei è stato osservato un evento del quale la più probabile interpretazione sembra essere31SiΛΛ con un decadimento successivo del tipo e con una energia di legameBΛΛ=(38.2±6.3) MeV.РеэюмеПроводится исследование с целью идентификации раэновидности гиперядер с двумя или более центрами распадов в ядерных змульсиях, зкспонированных в выведенном пучке K− меэонов с импульсом 3.0 ГзВ/с на протонном синхротроне в ЦЕРНе. В обраэце, содержашем 493 гиперядра, было обнаружено одно событие, наиболее вероятная интерпретация которого представляет31SiΛΛ с последуюшими модами и знергия свяэи составляетBΛΛ=(38.2±6.3) МзВ.

Normalization constant of the (α, t) reaction

SummaryThe DWBA analyses are performed for the ground states and other strong transitions populated in the (α, t) reaction on various targets ranging fromA = 16 to 208 with zero-range and with finite-range corrections in the local energy approximation (LEA). The normalization constants without and with the LEA are found to be, respectively,D20 = (18.16±3.49) × 10 MeV fm andD = (8.67±1.60)× 10 MeV2 fm3 which are reasonably consistent with some other previous studies. The normalization constants for the (α, t) reaction on the Al target are also deduced for different incident energiesEα = 25.0, 25.2, 64.5, 80.0 and 104.0 MeV for studying any possible energy dependence of the normalization constant. No tangible energy dependence was found in the present study and hence the LEA seems to be valid reliably within the energy range studied. The ratioD20/D bears a value of about 2.0 which is remarkably constant over the target masses and incident energies.