We extend our previous analysis of mirror matter admixtures to reproduce the |ΔI|=1/2 rule predictions in the decays Ω^-→Ξ^-π^0, Ω^-→Ξ^0π^-, and Ω^-→ΛK^-. The results are satisfactory, lending credibility to the possibility that the enhancement phenomenon may be attributed to such admixtures.
A search for the second forbidden electron capture of 123Te has been performed. A new technique for searches of rare nuclear decays using CdZnTe detectors has been established. After a measuring time of 195 h no signal could be found resulting in a lower half-life limit of T1/2 > 3.2 × 1016 years (95% CL) for this process. This clearly discriminates between existing experimental results which differ by six orders of magnitude, and our data are in strong favour of the result with longer half-lives.
The 12C + 16O decay of 28Si states populated in the 12C(20Ne, 28Si*) reaction has been studied at beam energies of 160 and 110 MeV. Evidence for 28Si excited states is observed for the excitation energy range of 25–45 MeV. Angular correlation analysis shows that the spins of these states lie in the range of 10–16 . These measurements further indicate that these breakup states are associated with the decay of a 28Si nucleus with a large deformation.
We evaluate the time delay in some of the established resonance regions of πN elastic scattering. In addition to the positive peaks corresponding to resonances, we identify broad regions of negative time delay or time advancement. We compare the resonance parameters determined with the time delay method with those from conventional methods and try to interpret our observation of time advancement.
The electric field in the crystal planar channels is studied by the self-consistent Thomas–Fermi method. The Thomas–Fermi equation and the corresponding boundary conditions are derived for crystal planar channels. The electric field in the channels of silicon crystal, the critical angles and the half-angles for channelling protons in them are calculated numerically. A reasonable agreement with the experimental data is obtained. The results show that the self-consistent Thomas–Fermi method for the crystal channels works well, and microscopic research of the channel electric field with the contributions of all atoms and the atomic polarization being taken into account is practical. We also predict the critical angles of high-energy positron channelling in the same channels for a further check of the theory.
The sensitivity of the present CNGS beam to the sub-dominant νμ ↔ νe oscillations in the region indicated by the atmospheric neutrino experiments is investigated. In particular, we present a revised analysis of the OPERA detector and discuss the sensitivity to θ13 of ICARUS and OPERA combined. We show that the CNGS beam optimized for ντ appearance will improve significantly (about a factor of 5) the current limit of CHOOZ and explore most of the region sin2 2θ13 (10−2).
We apply the R-matrix formalism to the 3He(n, p)3H and 7Be(n, p)7Li reactions, which play an important role in the big-bang nucleosynthesis. The cross sections are analysed along with the 4He and 8Be spectra near threshold. Neutron and proton widths of high-energy states are determined. A statistical analysis of the uncertainties provide fairly low error bars (typically 2% at the 1σ confidence level) on the reaction rates.
The reactions 16 O( 7 Li, 2n )a nd 16 O( 7 Li, np) populating 21 Na and 21 Ne have been studied at EL = 27 MeV using the GASP γ -detector array. The level scheme for 21 Na and 21 Ne has been extended to higher excitation energy. Spins and parities of the observed levels are assigned tentatively supporting th ei dentification of opposite parity structures connected by strong dipole transitions. The structure of these bands is interpreted as based on a reflection asymmetric cluster structure.
Quasi-binary reaction of the deuteron breakup p + d --> (PP) + 17 with the final proton-proton pair (pp) in the S-1(0) state is analysed at initial energies 0.5-2 GeV in the kinematics of backward elastic pd-scattering pd --> dp. On the basis of the main mechanisms of the pd --> dp process, including initial and final state interactions, we show that unpolarized cross section and spin observables of this reaction exhibit important properties of the half-off-shell pp(1S(0)) -scattering amplitude, which are relevant to the nucleon-nucleon interaction at short distances.
A general numerical solution of the dispersion integral relation between the real and the imaginary parts of the nuclear optical potential is presented. Fast convergence is achieved by means of the Gauss-Legendre integration method, which offers accuracy, ease of implementation and generality for dispersive optical model calculations. The use of this numerical integration method in the optical model parameter search codes allows for a fast and accurate dispersive analysis.
The structure of 1p-shell nuclei, including the neutron-rich Be-11 and Li-11, are studied within the shell model.The structure of nuclei near the beta-stability line can be well described. In contrast, using standard parameters for the residual interaction, a number of features of nuclei far from beta-stability, as for example the properties of the ground state of Be-11, are not reproduced by the shell model.More than 20 experimental level data of nuclei far from beta-stability are then selected to determine new effective parameters for the modified surface delta interaction and for the single-particle energies. With these parameters used in the calculation for the 1p-shell nuclei far from beta-stability, the agreement between computed results and experimental data becomes fair, and the parity inversion for the 1/2(+) ground state in Be-11 is correctly reproduced.The results suggest that the shell model with a proper modification of the parameters in the modified surface delta interaction can be used usefully in the description of the structure of exotic nuclei.
A compilation of all the available data on single prompt photon production in hadron-hadron interactions is presented, in both tabular and graphical form. An interpretation of these data in terms of the 'state-of-the-art' NLO theory is described with specific emphasis on the uncertainties involved. Comparisons of this theory with the individual data sets are made in order to indicate to the reader the scope and general status of the available data. For completeness, data on two-prompt-photon production are also included in a separate small section. All the data in this review can be found in and retrieved from the Durham-RAL HEP Databases together with data on a wide variety of other reactions.
The shapes of even-mass krypton nuclei are studied using a deformed Hartree-Fock calculation with the 56Ni core. It is found that nuclei with A=72-80 are oblate in shape and 82Kr is a transitional nucleus with near prolate oblate degeneracy. The low-lying states and the band crossing in 82Kr are studied by angular momentum projection from the deformed configurations. The compression of energy levels near 6h is seen to be due to the rotation alignment of neutrons in g9/2 orbits of oblate shape.
The measured beta -decay properties of the 'waiting-point' nuclei 130Cd and 80Zn, together with improved shell model predictions of T1/2 and Pn-values for their experimentally unknown N approximately=82 and 50 neighbours, can be directly related to the observed r-abundances in the A approximately=130 and 80 abundance peaks. Based on this result, new constraints are given on the stellar conditions under which the r-process has operated.
The ( pi +, pi -) reactions leading to the double isobaric analogue state (DIAS) have been studied at pion energies 50 to 300 MeV, with 14C as an example. The emphasis of the study has been on the effects of the pion-nucleon interaction range on the calculated double-charge-exchange (DCX) cross sections. The authors found that both the propagation of the intermediate pi 0 and the nucleon-nucleon correlation at short distances are strongly affected by the non-locality of the pi N interaction. Consequently, DCX reactions may be used to distinguish between different pi N interaction models.
