In this paper the first experiment of thermomagnetic writing of a hologram on a thin film of EuO and the reconstruction of the hologram is reported. Writing of the hologram is achieved by using a giant pulsed ruby laser as a source for thermomagnetization. Erasing of the hologram is accomplished by a small applied magnetic field. The ruby laser is used because of its ability to provide the energy required for writing in a time that is short compared with the thermo-relaxation time. A hologram with shallow angle (10 μ resolution) was recorded and the reconstruction of the hologram was done using a He–Ne laser as a source. The formation of the hologram is based on the fact that the index of refraction of the material is a function of magnetization. Thus, the different state of magnetization induced by the laser pulse acts as a phase-hologram for polarized light. Polarizing elements were used to observe the reconstructed images from the magnetic holograms. Results were also obtained for the diffraction intensity in the different orders of a simple thermo-magnetic hologram. An analysis is presented to interpret the observed phenomena and gives the calculated efficiency that can be obtained under ideal conditions.

The GLAST Burst Monitor (GBM) is designed to provide wide field of view observations of gamma-ray bursts and other fast transient sources in the energy range 10 keV to 30 MeV. The GBM is composed of several unshielded and uncollimated scintillation detectors (twelve NaI and two BGO) that are widely dispersed about the GLAST spacecraft. As a result, reconstructing source locations, energy spectra, and temporal properties from GBM data requires detailed knowledge of the detectors' response to both direct radiation as well as that scattered from the spacecraft and Earth's atmosphere. This full GBM instrument response will be captured in the form of a response function database that is derived from computer modeling and simulation. The simulation system is based on the GEANT4 Monte Carlo radiation transport simulation toolset, and is being extensively validated against calibrated experimental GBM data. We discuss the architecture of the GBM simulation and modeling system and describe how its products will be used for analysis of observed GBM data. Companion papers describe the status of validating the system.

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The interactions between Ni and NiO were investigated by examining the magnetic properties of Ni films on single-crystal NiO substrates. The orientations of the NiO substrates were (001) (compensated spin planes), and (111) (parallel spin planes). With (001) NiO the Ni films were strained an amount corresponding approximately to the rhombohedral deformation of NiO below its Néel temperature. The amplitude and symmetry of magnetic torque data were consistent with the magnitude of this strain and the symmetry of the antiferromagnetic domain structure, respectively. Ni films on (111) NiO substrates had a complex field dependence of rotational hysteresis. This behavior was analyzed in terms of exchange anisotropy coupling and the interaction of the field with both the Ni and NiO spin systems. The analysis provided good agreement with the data for an exchange anisotropy energy of 1.75 erg/cm2 of interface, a crystalline anisotropy of NiO in its parallel spin plane of 1.1×103 erg/cc NiO, and a ``flop field'' for NiO in its parallel spin plane of 5 to 10 kOe. The analysis showed that two new regions of rotational hysteresis loss are present in fields ≥ the ``flop field'' of the antiferromagnetic spin system. Some more general features of exchange anisotropy coupling are also discussed.