H. M. Sen Gupta

A study of nuclear structure in 59Ni from the (d, p) reaction on 58Ni

Abstract Level structure in 59 Ni is studied from the (d, p) reaction in 58 Ni using the Aldermaston tandem Van de Graaff accelerator and the multichannel magnetic spectrograph. Angular distributions of protons are measured over the angular range 5°–175° up to an excitation of ≈ 8 MeV and absolute cross sections are measured. The data are analysed in terms of the finite-range DWBA theory of direct reactions and spins, parities and spectroscopic factors are deduced for various levels. The summed spectroscopic factors and the single-quasiparticle energies of the shell-model states are obtained. Properties of the low-lying levels in 59 Ni are compared with predictions based on exact shell-model calculations.

A study of the level structure in 57Fe from the (d, p) reaction on 56Fe

Abstract The reaction 56 Fe(d, p) 57 Fe is investigated at 12 MeV using the Aldermaston multi-channel magnetic spectrograph. The angular distributions of protons leading to various states in 57 Fe upto an excitation of 6.7 MeV are measured over an angular range 5°–175°. The data are analysed with the distorted wave Born approximation calculations; a satisfactory agreement is found in most cases upto about 100°. Spin, parity and the spectroscopic factors for various states are obtained and the positions of the single-quasiparticle energies determined. The results are compared with those for the isotonic nuclei 55 Cr and 59 Ni and with the pairing theory.

A study of the levels in 56Fe from inelastic scattering of deuterons

Abstract Energy levels in 56 Fe have been obtained up to an excitation of 4.5 MeV from the inelastic scattering of 12 MeV deuterons by using a multi-gap magnetic spectrograph with nuclear emulsion as the detector. Angular distributions for these levels were measured, and the results were analysed in terms of the distorted-wave method using the collective model of interaction by deforming both real and imaginary parts of the optical potential. Good agreement was found for the first 2 + and the octupole vibrational states, and the corresponding deformation parameters were extracted.

A study of some proton capture resonance reactions on52Cr and56Fe

SummaryThe52Cr(p, γ)53Mn and56Fe(p, γ)57Co resonance reactions have been studied atEp=1388, 1395, 1608 and 1901 keV and atEp=1248, 1652 and 2065 keV, respectively. Decay schemes are constructured and spins of the resonance levels are determined from the measurements of angular distributions of several primary gamma-rays.RiassuntoSono state studiate le reazioni di risonanza52Cr(p, γ)53Mn e56Fe(p, γ)57Co aEp=1388, 1395, 1608 e 1901 keV eEp=1248, 1652 e 2065 keV, rispettivamente. Si costruiscono gli schemi di decadimento e si determinano gli spin dei livelli di risonanza dalle misure delle distribuzioni angolari di alcuni raggi gamma primari.РезюмеИсследуются резонансные реакции52Cr(p, γ)53Mn и56Fe(p, γ)57Co приEp=1388, 1395 и 1901 кэВ и приEp=1248, 1652 и 2065 кэВ, соответственно. Конструируются схемы распадов и определяются спины резонансных уровней из измерений угловых распределений некоторых гамма-лучей.

Level structure of 51Cr from the (d, p) reaction on 50Cr

Abstract The level structure of 51 Cr is studied through the 50 Cr(d, p) reaction at E d = 12 MeV using the Van de Graaff accelerator and multi-channel magnetic spectrograph at AERE, Harwell. A total of 174 levels was observed up to E x ≈ 8.1 MeV. The stripping angular distributions are analysed in terms of the DWBA model with NLFR corrections. Spins, parities and spectroscopic factors are obtained for various levels and a sum rule analysis is made. Hauser-Feshbach calculations are done for the non-stripping levels and the levels showing a poor DWBA fit. Finally, the level spectrum is compared with the MBZ and MS models.

Level properties of 50V through the 51V(τ, alpha;) reaction

Abstract The 51 V(τ, α) 50 )V reaction has been studied at E τ = 18.0 MeV using a multichannel magnetic spectrograph. Seventy levels up to an excitation of 9.3 MeV have been observed, including five analogues. The angular distributions have been analysed in terms of the DWBA theory of direct reactions; a sum rule analysis has been made with the spectroscopic strengths so obtained. The effects of non-locality and finite range in the optical potential and of the cut-off radius and optical model parameter sets were also studied. Except for a few levels, the l -assignments agree well with previous neutron pick-up work; some new assignments of l -values are also made. In addition to l = 0, 2 and 3 transitions, a few weak l = 1 transitions were also observed.

Level structure of 47Ti from the (d, p) reaction in 46Ti

Abstract The reaction 46 Ti(d, p) is studied at 10 MeV using the Aldermaston tandem Van de Graaff accelerator and a multichannel magnetic spectrograph. A total of 180 levels are observed up to an excitation of ≈ 7.2 MeV and the stripping angular distributions are analysed in terms of the DWBA theory of direct reactions using the NL/FR optical model potential. Spins, parities and spectroscopic factors are deduced for various levels. Summed spectroscopic factors and quasiparticle energies are obtained for shell model states. Properties of low-lying levels in 47 Ti are compared with the MBZ and Coriolis coupling models and also with those of the isotonic nuclei 45 Ca and 46 Sc.

Local optical model studies of pion-nucleus scattering

Local optical model calculations have been carried out for elastic and inelastic scattering of ?? from 40,42,44,48Ca and 54Fe at pion energies atop, above and below the ? resonance. The elastic studies resulted in considerable ambiguities in the parameter values. Using the best-fit parameters, zero-range DWBA calculations have been carried out for inelastic scattering of ?? leading to the lowest 2+ and 3- states of these nuclei. Transition strengths extracted from inelastic scattering, compared with known values, remove the ambiguity found for elastic scattering, making the simple model useful for other reaction studies with pions.

Strong-absorption model for scattering of helions and tritons

SummaryThe 3-parameter strong-absorption model of Frahn and Venter is used to analyse the helion and triton elastic-scattering data from some nuclei between C and Sn. A satisfactory agreement is obtained in heavier nuclei, whereas the fit is rather poor in light nuclei. Interaction radius and surface diffuseness are obtained from the best-fit parameter values ofT, Δ andμ. Inelastic scattering of helions from24Mg,56Fe,58Fe and58Ni is also analysed and the deformation parameterβ2 is obtained.RiassuntoSi usa il modello dell’assorbimento forte a tre parametri di Frahn e Venter per analizzare i dati sullo scattering elastico di elioni e tritoni da parte di alcuni nuclei fra il C e lo Sn. Si ottiene un accordo soddisfacente pei nuclei più pesanti, mentre l’adattamento è scarso pei nuclei leggeri. Si ottengono il raggio di interazione e la diffusione superficiale dai valori dei parametri di miglior adattamentoT, Δ eμ. Si analizza anche lo scattering anelastico di elioni su24Mg,56Fe,58Fe e58Ni e si ottiene il parametro di deformazioneβ2.РеэюмеТрех-параметрическая модель сильного поглошения Франа и Вентера испольэуется для аналиэа данн& qyх по упругому рассеянию ядер гелия и трития на некоторых ядрах между C и Sn. B области тяжелых ядер получается удовлетворительное согласие, тогда как в области легких ядер соответствие довольно плохое. Йэ наилучщей подгонки величин параметровT, Δ иμ. получаются радиус вэаимодействия и диффуэность поверхности. Также аналиэируется неупругое рассеяние ядер гелия на24Mg,56Fe,58Fe и58Ni, и определяется параметр деформацииβ2.

Optical model analysis of the elastic scattering of 20–24 MeV α-particles by 12C, 14N, 16O and 20Ne

Abstract An optical model analysis is presented for angular distributions of elastic scattering of 20 to 24 MeV α-particles from 12C, 14N, 16O and 20Ne. Families of parameters are found characterised by differences in the volume integral per interacting nucleon pair for the real potential of the order of 100 MeV · fm3, in agreement with similar analysis fir heavier targets. The value of the real potential at an equivalent semiclassical strong absorption radius is shown to be a significant parameter in this analysis, again in agreement with results for heavier targets. A characteristic of most of the optical model fits is the very small value of the imaginary surface diffuseness parameter.