Spectrum of multicluster states of 44Ti nucleus in the generalized Elliott SU(3) model

The multicluster levels of ⁴⁴Ti nucleus have been investigated in the generalized Elliott model. It is shown that the Hamiltonian of this model reproduces fairly well the energy levels of the ⁴⁴Ti nucleus spectrum with zero values of the spin S and isospin T, produced in the (⁶ Li, d) reaction at energies of 37 and 50 MeV. The high-spin levels of ⁴⁴Ti are predicted.     

Evidence for particle-core coupling in the Te nucleus

The high-spin states of ¹²⁵Te have been investigated using the ¹²⁴Sn (α, 3nγ) reaction and the in-beam technique. Besides low-spin levels observed in the radioactive decay, the high-spin positive- and negative-parity bands have been established. As a possible explanation of the nature of the excited states in ¹²⁵Te the idea of the odd-neutron(hole)-core coupling is discussed.     

The 44Ti(alpha,p) reaction and its implication on the 44Ti yield in supernovae

Cross sections for the 44Ti(alpha,p)47V reaction which significantly affects the yield of 44Ti in supernovae were measured in the energy range 5.7 MeV相似文献   

Core-excited α-cluster structure in44Ti

With the use of a schematic⁴⁰Ca^*+α model, the low-lying positiveK=O2+ and 2⁺ bands in⁴⁴Ti, which start from the band-head energyE _x =1.90 MeV and 2.88 MeV, respectively, are shown to be well interpreted by an α-cluster structure with an excited⁴⁰Ca core, i.e.,³⁶Ar+α+α structure.     

Evidence for clustering in Mn-doped CeO2

Electron spin resonance spectra of manganese-doped cerium oxide have been studied at room temperature for Ce concentrations between 0.01 and 1.00 mol%. The linewidths and intensities of the lines associated with isolated manganese ions have a maximum between 0.20 and 0.40 mol%. The results suggest that the solid solution of Mn in CeO₂ is not random, but exhibits significant clustering effects.     

Critical radii for alpha-particle elastic scattering

The critical radii obtained from analyses of the elastic scattering of alpha-particles by a range of nuclei are found to be closely connected with the nuclear matter distributions obtained by summing the squares of single-particle wavefunctions. This provides a method of calculating the details of the optical potentials from the structure of the target nucleus.     

The temperature dependence of the nuclear quadrupole interaction of 44Ti(EC)44Sc in rutile

The temperature dependence of the Nuclear Quadrupole Interaction on ⁴⁴Sc in rutile was measured by Time Differential Perturbed Angular Correlation in the temperature range from 300 K to 945 K. Whereas $\upomega _{\rm Q} = \mathrm{eQV}_{\rm zz}/4\rm \hbar$ with V_zz denoting the largest component of the electric field gradient tensor in magnitude increases with increasing temperature, the asymmetry parameter η remains essentially constant. This observation fits into the systematic with other probes provided the sign of V_zz is negative.     

Evidence for trimer formation during dipole clustering in Mg doped LiF

The clustering of (Mg²⁺V^?) pairs in LiF into higher order complexes is followed using dielectric loss and ITC. The results show clearly that, even at low temperatures and with high impurity content crystals, the decay follows a third-order reaction indicating that trimers are the predominant clusters formed. This is supported by the ITC results which do not give any indication of dimer formation.Difficulties may arise with the measurement of dielectric loss. An additional transient signal at ~1 kHz is observed to grow and then decay with aging time at 25°C. This signal is thought to be associated with the presence of dislocations introduced into the crystals during rapid quenching.     

Evidence for shape coexistence in the N=Z nucleus 7236Kr36

Gamma rays associated with the decay of states in the N=Z nucleus ⁷²Kr have been identified following the ¹⁶O(⁵⁸Ni, 2n) ⁷²Kr reaction at a mean beam energy of 170 MeV. Identification was made using the Daresbury Recoil Separator. The first excited state was found to be at 709.1 ± 0.3 keV and to be populated with a cross section of 60 ± 25 υb. The pattern of gamma rays associated with ⁷²Kr indicates the co-existence of nuclear shapes.     

Evidence for strong clustering effects in high-multiplicity final states at 30 GeV

A statistical analysis of the event-to-event fluctuations of the langitudinal-momentum distributions is applied to 2-, 3-, 4- and 6-pion production data in $\text{28}\text{GeV}\text{c}$ proton-nucleon collisions, as well as to several models. The results indicate that a dominant feature of these final states is the formation of high-multiplicity clusters of particles.     

Resonance spectroscopy of44Ti in the excitation energy range 9.05 to 10.28 MeV

The absolute differential cross sections for the⁴⁰Ca(α,α)⁴⁰Ca reaction have been measured in the bombarding energy range from 4.33 to 5.68 MeV at the four laboratory angles 85°, 125°, 141° and 165°. An analysis of the data using multilevelR matrix theory has provided the spin-parities and widths of 29 levels in the compound nucleus⁴⁴Ti. A comparison has been made with the levels deduced from the (α,γ) reaction and existing theoretical calculations of⁴⁴Ti levels.     

Backward-angle anomalies in alpha-particle elastic scattering

The backward-angle anomalies in elastic alpha-particle scattering have been recently attirbuted to exchange processes such as heavy-particle stripping and knock-on. Using a parameter-free treatment, it is shown that the so far neglected one-particle exchange arising from the antisymmetrisation between the projectile and the target nucleus is important and should be considered in any quantitative analysis of the anomalous alpha-backscattering.     

High energy proton-carbon scattering in the alpha-particle model

We investigate elastic and inelastic 0⁺–2⁺ high energy proton-¹²C scattering in the alpha-particle model. We use a rigid equilateral triangle nuclear wave function with a Gaussian dispersion function allowing theα-particles of the¹²C-nucleus to deviate from their most probable positions at the triangle vertices. Expressions for the differential scattering cross sections are deduced using Glauber multiple diffraction theory. Thus we need thep?α-particle scattering amplitude, which is calculated from a Gaussian nucleon-nucleon profile function. Numerical calculations show that the model reproduces the experimental results onp?α andp-¹²C scattering.     

Electromagnetic transition properties and isospin excitation in the cross-conjugate nuclei 44Ti and 52Fe

The interacting boson model with isospin (IBM-3) is applied to study the band structure and electromagnetic transition properties of the low-lying states in the cross-conjugate nuclei 44Ti and S2Fe. The isospin excitation states with T=0, 1 and 2 are identified and compared with available data. The E2 and M1 matrix elements for the low-lying states have been investigated. According to this study, the 2+3 state is the lowest mixed symmetry state in the cross-conjugate nuclei 44Ti and 52Fe. The excitation energy of the second 0+2 and 2+2 states with T=0 in the nucleus 52Fe are identified. The agreement between the model calculations and data is reasonably good.     

Properties of alpha-particle solutions to the many-nucleon problem

A class of A-nucleon (for even N = Z) Hamiltonians is found such that they admit, among others, solutions that can be exactly related to solutions to the problem of A/4 alpha particles in the sense that the respective eigenvalues of the two problems coincide and that the A-nucleon solutions can be constructed from the alpha-particle solutions within a procedure that follows from the resonating-group model. It is shown that an effective nuclear Hamiltonian close to a realistic one possesses these properties, the alpha-particle states in nuclei having basic properties of an alpha condensate and, frequently, a normal nuclear density. The statistics of alpha particles (and other composite bosons) proves to be different from Bose-Einstein and Fermi-Dirac statistics and from parastatistics.     

Triton and alpha-particle contribution from LiF converter for neutron dosimeter

A personnel neutron dosimeter prototype based on chemical and electrochemical etched CR-39 detector, combined with LiF converter, has been calibrated using an ICRP-like phantom, under a heavy-water moderated Californium source neutron spectra; A conversion factor of 1.052±126 spots cm⁻² mSv⁻¹ was obtained. The sealing properties of the detector holder showed a ten-fold reduction in radon background when it was tested in a high radon atmosphere. A convenient mechanical shock resistance was achieved in LiF converters by sintering to 11 tons pressure LiF powder at 650°C, during one hour.     

High-spin proton and alpha-particle emission as probes for nuclear structure

During recent years the nuclear decay modes of discrete prompt proton and α-particle emission from (super)deformed high-spin states have been discovered in nuclei in the vicinity of ⁵⁶Ni. The latest news from experiments performed at EUROBALL and GAMMASPHERE regarding these decays are presented and discussed. Published online: 31 October 2002 RID="a" ID="a"e-mail: dirk.rudolph@kosufy.lu.se     

Nuclear surface waves in alpha-particle and ion-ion collisions

Our earlier methods of interpretation of the resonances in ion-ion scattering (such as ¹²C + ¹²C, ¹²C + ¹⁶O, or ¹⁶O + ¹⁶O where they appear both experimentally and via optical-model calculations) in terms of nuclear surface waves are applied to the case of α-⁴⁰Ca scattering. The optical-model resonance results of Brink et al. are here extended in order to render them suitable for a surface-wave picture as well. Recent experimental results on ¹²C + ¹²C scattering are used to demonstrate the existence of surface waves of both Rayleigh and whispering gallery type in this system.