Sub-barrier fusion with the He-6 halo nucleus

The fusion-fission cross sections of the He-4 + U-238 and He-6 + U-238 systems have been measured, at Louvain-la-Neuve (Belgium), for energies around and below the barrier. The helium projectiles impinges on a UF4 target. The fission fragments and the possible projectile residue are detected using an array of Si detectors for angles ranging from 30 to 150 degrees. The data taken with He-4 are in good agreement with previous data and with the fusion calculation. The He-6 data show a regular trend with an enhancement below the barrier compared to He-4 + U-238 or Li-6 + U-238. This enhancement could be due to the fusion process itself or to a transfer component which triggers the fission without being detected in our set-up. The data for the A=4 and A=6 isobars are compared to a simple barrier penetration model

Spectroscopy of He-7 using the Be-9(He-6, Be-8) transfer reaction

The unbound nucleus He7 has been investigated via the reaction of a 16.8 MeV He6 radioactive ion beam on a Be9 target. The measurement of the outgoing Be8 through its well characterized two-α decay permitted the energy of the He6+n system to be reconstructed. Through comparison with a complete Monte Carlo simulation incorporating R-matrix lineshapes, the He7 ground state was determined to lie 0.380(28) MeV above the neutron decay with a width of Γ=0.179(21) MeV. A neutron spectroscopic factor SF=0.608(18) was extracted in agreement with the most recent calculations. Significant evidence was found for a broad resonance lying at 2.6(2) MeV above threshold with a ΓFWHM=2.3(3) MeV. These parameters are fully consistent with the properties of 1/2− state reported by Wuosmaa et al. [Phys. Rev. C 72, 061301(R) (2005)]. Limits were also put on the presence of narrow resonances seen in earlier experiments.status: publishe

Structure of exotic nuclei from direct reactions

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Fission yield studies at the IGISOL facility

Low-energy-particle-induced fission is a cost-effective way to produce neutron-rich nuclei for spectroscopic studies. Fission has been utilized at the IGISOL to produce isotopes for decay and nuclear structure studies, collinear laser spectroscopy and precision mass measurements. The ion guide technique is also very suitable for the fission yield measurements, which can be performed very efficiently by using the Penning trap for fission fragment identification and counting. The proton- and neutron-induced fission yield measurements at the IGISOL are reviewed, and the independent isotopic yields of Zn, Ga, Rb, Sr, Cd and In in 25MeV deuterium-induced fission are presented for the first time. Moving to a new location next to the high intensity MCC30/15 light-ion cyclotron will allow also the use of the neutron-induced fission to produce the neutron rich nuclei at the IGISOL in the future

Prevalence and risk factors of neurological impairment among children aged 6–9 years: from population based cross sectional study in western Kenya

<p>Abstract</p> <p>Background</p> <p>The burden of disability is more severe among children in low income countries. Moreover, the number of children with disabilities (CWDs) in sub-Saharan Africa is predicted to increase with reduction in child mortality. Although the issue on CWDs is important in sub-Saharan Africa, there are few researches on risk factors of disabilities. The purpose of this study was to evaluate the risk factors of neurological impairment (NI) among children in western Kenya.</p> <p>Methods</p> <p>The present study was conducted in Mbita district (which has high HIV infectious prevalence), Kenya from April 2009 to December 2010. The study consisted of two phases. In phase 1, the Ten Question Questionnaire (TQQ) was administered to all 6362 caregivers of children aged 6–9 years. In phase two, all 413 children with TQQ positive and a similar number of controls (n=420) which were randomly selected from children with TQQ negative were examined for physical and cognitive status. In addition, a structured questionnaire was also conducted to their caregivers.</p> <p>Results</p> <p>The prevalence was estimated to be 29/1000. Among the types of impairments, cognitive impairment was the most common (24/1000), followed by physical impairment (5/1000). In multivariate analysis, having more than five children [adjusted odds ratio (AOR): 2.85; 95%IC: 1.25 – 6.49; p=0.013], maternal age older than 35 years old [AOR: 2.31; 95%IC: 1.05 – 5.07; p=0.036] were significant factors associated with NI. In addition, monthly income under 3000 ksh [AOR: 2.79; 95%IC: 1.28 – 6.08; p=0.010] and no maternal tetanus shot during antenatal care [AOR: 5.17; 95%IC: 1.56 – 17.14; p=0.007] were also significantly related with having moderate/severe neurological impairment.</p> <p>Conclusion</p> <p>It was indicated that increasing coverage of antenatal care including maternal tetanus shot and education of how to take care of neonatal children to prevent neurological impairment are important.</p