Magnetocardiography with a modular spin-exchange relaxation free atomic magnetometer array

We present a portable four-channel atomic magnetometer array operating in the spin exchange relaxation-free regime. The magnetometer array has several design features intended to maximize its suitability for biomagnetic measurement, specifically foetal magnetocardiography, such as a compact modular design, and fibre coupled lasers. The modular design allows the independent positioning and orientation of each magnetometer, in principle allowing for non-planar array geometries. Using this array in a magnetically shielded room, we acquire adult magnetocadiograms. These measurements were taken with a 6-11 fT Hz^(-1/2) single-channel baseline sensitivity that is consistent with the independently measured noise level of the magnetically shielded room.Comment: 15 pages, 5 figure

The design and thermo-structural analysis of target assembly for high intensity neutron source

The engineering design of an integrated target assembly of IFMIF lithium target was performed in IFMIF/EVEDA project for a high intensity neutron source. In the evaluation of the design, a thermos-structural analysis of was evaluated by ABAQUS code, and the modeling region was a part of the target assembly which was from the inlet nozzle to the outlet pipe. The material of the target assembly including the back plate was F82H steel. In the thermal-structural analysis, the normal operations and start/stop or abnormal operations were evaluated at 250 or 300 °C operation of Li flow in inlet pipe. The result showed that the temperature of the target assembly was evaluated to be still lower than the Li boiling point of 344 °C under a vacuum pressure of 10−3 Pa. In a temperature constant operation, the calculated stresses and displacements were small enough for thermal soundness of the target assembly in steady states. In a transient cooling process from 300 °C to 20 °C through 250 °C, the maximum Mises stress was found to be 372 MPa, which was lower than the yield stress at 300 °C. Keywords: High intensity neutron source, Target assembly, Thermo-structural analysis, Li target, IFMIF, F82

Backward-angle photoproduction of π0\pi^0 mesons on the proton at EγE_\gamma = 1.5--2.4 GeV

Differential cross sections and photon beam asymmetries for $\pi^0$ photoproduction have been measured at $E_\gamma$ = 1.5--2.4 GeV and at the $\pi^0$ scattering angles, --1 $<$ cos$\Theta_{c.m.} <$ --0.6. The energy-dependent slope of differential cross sections for $u$-channel $\pi^0$ production has been determined. An enhancement at backward angles is found above $E_\gamma$ = 2.0 GeV. This is inferred to be due to the $u$-channel contribution and/or resonances. Photon beam asymmetries have been obtained for the first time at backward angles. A strong angular dependence has been found at $E_\gamma >$ 2.0 GeV, which may be due to the unknown high-mass resonances.Comment: 12 pages, 4 figures, submitted to PL