437 research outputs found

    Determinants of Informal Financial Group Participation: Evidence from Rural Cameroon

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    This paper analyzes the determinants of individual participation in informal financial groups (IFGs). The findings indicate that group characteristics are a primary factor explaining IFG participation, while transaction costs also play an important role. Results highlight the broad scope of individuals (by gender, age, occupation) participating in IFGs

    Potential and limitations of nucleon transfer experiments with radioactive beams at REX-ISOLDE

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    As a tool for studying the structure of nuclei far off stability the technique of gamma-ray spectroscopy after low-energy single-nucleon transfer reactions with radioactive nuclear beams in inverse kinematics was investigated. Modules of the MINIBALL germanium array and a thin position-sensitive parallel plate avalanche counter (PPAC) to be employed in future experiments at REX-ISOLDE were used in a test experiment performed with a stable 36S beam on deuteron and 9Be targets. It is demonstrated that the Doppler broadening of gamma lines detected by the MINIBALL modules is considerably reduced by exploiting their segmentation, and that for beam intensities up to 10^6 particles/s the PPAC positioned around zero degrees with respect to the beam axis allows not only to significantly reduce the gamma background by requiring coincidences with the transfer products but also to control the beam and its intensity by single particle counting. The predicted large neutron pickup cross sections of neutron-rich light nuclei on 2H and 9Be targets at REX-ISOLDE energies of 2.2 MeV A are confirmed.Comment: 11 pages, 8 figure

    Rural finance for food security for the poor

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    In this Food Policy Review, the authors take a fresh look at the role of rural financial policy in improving household food security and alleviating poverty. They develop a conceptual framework for relating access to financial services to food security and review empirical findings on household demand for financial services. They explore the potentials for linking informal lenders (relatives, credit groups, and moneylenders) with the formal financial systems (banks and cooperatives). Then they review the constraints to development of rural financial markets and ways to circumvent these constraints by examining innovative institutions, especially those that include participation by the poor themselves.Financial institutions. ,Rural credit Developing countries. ,Rural poor. ,Food security Household. ,Poverty alleviation. ,Community participation. ,Microfinance ,

    First Results on In-Beam gamma Spectroscopy of Neutron-Rich Na and Mg Isotopes at REX-ISOLDE

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    After the successful commissioning of the radioactive beam experiment at ISOLDE (REX-ISOLDE) - an accelerator for exotic nuclei produced by ISOLDE - first physics experiments using these beams were performed. Initial experiments focused on the region of deformation in the vicinity of the neutron-rich Na and Mg isotopes. Preliminary results show the high potential and physics opportunities offered by the exotic isotope accelerator REX in conjunction with the modern Germanium gamma spectrometer MINIBALL.Comment: 7 pages, RNB6 conference contributio

    Self energies of the pion and the delta isobar from the ^3He(e,e'pi^+)^3H reaction

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    In a kinematically complete experiment at the Mainz microtron MAMI, pion angular distributions of the 3^3He(e,e'π+)3\pi^+)^3H reaction have been measured in the excitation region of the Δ\Delta resonance to determine the longitudinal (LL), transverse (TT), and the LTLT interference part of the differential cross section. The data are described only after introducing self-energy modifications of the pion and Δ\Delta-isobar propagators. Using Chiral Perturbation Theory (ChPT) to extrapolate the pion self energy as inferred from the measurement on the mass shell, we deduce a reduction of the π+\pi^+ mass of Δmπ+=(1.72.1+1.7)\Delta m_{\pi^+} = (-1.7^{+ 1.7}_{- 2.1}) MeV/c2^2 in the neutron-rich nuclear medium at a density of ρ=(0.0570.057+0.085)\rho = (0.057^{+ 0.085}_{- 0.057}) fm3^{-3}. Our data are consistent with the Δ\Delta self energy determined from measurements of π0\pi^0 photoproduction from 4^4He and heavier nuclei.Comment: Elsart, 12 pages and 4 figures, Correspondent: Professor Dr. Dr. h.c. mult. Achim Richter, [email protected], submitted to Phys. Rev. Let

    "Safe" Coulomb Excitation of 30Mg

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    We report on the first radioactive beam experiment performed at the recently commissioned REX-ISOLDE facility at CERN in conjunction with the highly efficient gamma spectrometer MINIBALL. Using 30Mg ions accelerated to an energy of 2.25 MeV/u together with a thin nat-Ni target, Coulomb excitation of the first excited 2+ states of the projectile and target nuclei well below the Coulomb barrier was observed. From the measured relative de-excitation gamma ray yields the B(E2; 0+ -> 2+) value of 30Mg was determined to be 241(31) e2fm4. Our result is lower than values obtained at projectile fragmentation facilities using the intermediate-energy Coulomb excitation method, and confirms the theoretical conjecture that the neutron-rich magnesium isotope 30Mg lies still outside the ``island of inversion''

    High-precision Studies of the 3^{\bf{3}}He(e,e^{\bf{\prime}}p) Reaction at the Quasielastic Peak

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    Precision studies of the reaction 3^{3}He(e,e^\primep) using the three-spectrometer facility at the Mainz microtron MAMI are presented. All data are for quasielastic kinematics at q=685|\vec{q} | =685 MeV/c. Absolute cross sections were measured at three electron kinematics. For the measured missing momenta range from 10 to 165 MeV/c, no strength is observed for missing energies higher than 20 MeV. Distorted momentum distributions were extracted for the two-body breakup and the continuum. The longitudinal and transverse behavior was studied by measuring the cross section for three photon polarizations. The longitudinal and transverse nature of the cross sections is well described by a currently accepted and widely used prescription of the off-shell electron-nucleon cross-section. The results are compared to modern three-body calculations and to previous data.Comment: 4 pages, 3 figures. Submitted for publication in Phys. Rev. Let

    Search for narrow nucleon resonances below pion threshold in the H(e,e′π+)X and 2H(e,e′p)X reactions

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    In two series of high-resolution coincidence experiments at the three-spectrometer facility at MAMI, the H(e, epi+)X and 2H(e, ep)X reactions were studied to search for narrow nucleon resonances below pion threshold. The missing-mass resolution was 0.6-1.6 MeV/c2 full width at half maximum in the proton experiment and 0.9-1.3 MeV/c2 in the deuteron experiment. The experiments covered the missing-mass region from the neutron mass up to about 1050 and 1100 MeV/c2, respectively. None of our measurements showed a signal for narrow resonances to a level of down to 10-4 with respect to the neutron peak in the missing-mass spectra
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