Switching field and thermal stability of CoPt/Ru dot arrays with various thicknesses

The switching fields and thermal stability of CoPt/Ru dot arrays with various dot thickness delta (5-20 nm) were experimentally investigated as a function of the dot diameter, D, (130-300 nm). All dot arrays showed a single domain state, even after removal of an applied field equal to the remanence coercivity Hr. The angular dependence of Hr for the dot arrays indicated coherent rotation of the magnetization during nucleation. We estimated the values of the "intrinsic" remanence coercivity H0 obtained by subtracting the effect of thermal agitation on the magnetization and the stabilizing energy barrier to nucleation E0/(kBT). The variation in H0 as a function of delta and D was qualitatively in good agreement with that of the effective anisotropy field at the dot center Hk eff(r=0), calculated taking account of the demagnetizing field in the dots. The ratio of H 0 to Hk eff(r=0) for the dot arrays with delta=10 nm increased from 0.53 to 0.70 as D decreased from 300 to 140 nm, and no significant difference in the H0/Hk eff(r=0) ratio due to the difference in delta was observed. On the other hand, E0/(k BT) decreased as delta decreased. E0/(kBT) increased slightly as D decreased, but, was not so sensitive to D over the present D rang

Shallow and diffuse spin-orbit potential for proton elastic scattering from neutron-rich helium isotopes at 71 MeV/nucleon

Vector analyzing powers for proton elastic scattering from 8He at 71 MeV/nucleon have been measured using a solid polarized proton target operated in a low magnetic field of 0.1 T. The spin-orbit potential obtained from a phenomenological optical model analysis is found to be significantly shallower and more diffuse than the global systematics of stable nuclei, which is an indication that the spin-orbit potential is modified for scattering involving neutron-rich nuclei. A close similarity between the matter radius and the root-mean-square radius of the spin-orbit potential is also identified.Comment: 6 pages, 4 figures, accepted for publication in Physical Review C Rapid Communicatio

Coulomb and nuclear breakup of a halo nucleus 11Be

Breakup reactions of the one-neutron halo nucleus 11Be on Pb and C targets at about 70 MeV/u have been investigated by measuring the momentum vectors of the incident 11Be, outgoing 10Be, and neutron in coincidence. The relative energy spectra as well as the angular distributions of the 10Be+n center of mass have been extracted for both targets. For the breakup on Pb target, the selection of forward scattering angles is found to be effective to extract almost purely the first-order E1 Coulomb breakup component, and to exclude the nuclear contribution and higher-order Coulomb breakup components. This angle-selected energy spectrum is thus used to deduce the spectroscopic factor for the 10Be(0+) 2s_1/2 configuration in 11Be which is found to be 0.72+-0.04 with B(E1) up to Ex=4 MeV of 1.05+-0.06 e2fm2. The energy weighted E1 strength up to Ex=4 MeV explains 70+-10% of the cluster sum rule, consistent with the obtained spectroscopic factor. The non-energy weighted sum rule is used to extract the root mean square distance of the halo neutron to be 5.77(16) fm, consistent with previously known values. In the breakup with C target, we have observed the excitations to the known unbound states in 11Be at Ex=1.78 MeV and 3.41 MeV. Angular distributions for these states show the diffraction pattern characteristic of L=2 transitions, resulting in J^pi =(3/2,5/2)+ assignment for these states. We finally find that even for the C target the E1 Coulomb direct breakup mechanism becomes dominant at very forward angles.Comment: 14 pages, 7 figures, accepted for publication on Physical Review

Comparison of Dermatophytes and Other Agents of Human Dermatitis between Males and Females in Jos, Plateau State, Nigeria

Dermatophytes are a group of three genera of fungi namely Microsporum spp, Trichophyton spp and Epidermophyton spp that commonly cause infections of the skin, hair and nails due to their ability to utilize keratin in both man and animals. Dermatophytes and other agents of human dermatitis are believed to have gender predisposition because of the anatomical and physiological nature of these genders. A study was undertaken to compare the distribution of dermatophytes and other agents of human dermatitis in patients who visited the Dermatophilosis Research Laboratory, National Veterinary Research Institute, Vom, Plateau State of Nigeria. A total of 1551 patients were involved in this study from 2003 to 2007; 823 of whom were males and 728 females. Samples collected were skin scrapping, nails, hair and pus exudates. They were processed according to standard procedures. Nine hundred and thirty two (60%) were positive for dermatophytes and other agents. Sporothrix schenckii (138 (12.4%)), Aspergillus flavus (128 (11.5%)), and Trichophyton mentagrophytes (112 (10.1%)), Mucor sp (105 (9.5%)) were the most commonly isolated fungi. Aspergillus flavus occurred more in males (74 (6.7%)) while Sporothrix schenckii was more in females (71 (6.4%)). More isolation was made from the head in males (185 (19.8%)) while in females more isolation was made from their limbs (150 (16.1%)). Males generally were more affected with skin infections than females