High precision measurements of the differential cross sections for π0 photoproduction at forward angles for two nuclei, 12C and 208Pb, have been performed for incident photon energies of 4.9-5.5 GeV to extract the π0→γγ decay width. The experiment was done at Jefferson Lab using the Hall B photon tagger and a high-resolution multichannel calorimeter. The π0→γγ decay width was extracted by fitting the measured cross sections using recently updated theoretical models for the process. The resulting value for the decay width is Γ(π0→γγ)=7.82±0.14(stat)±0.17(syst)  eV. With the 2.8% total uncertainty, this result is a factor of 2.5 more precise than the current Particle Data Group average of this fundamental quantity, and it is consistent with current theoretical predictions.

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Metal Vapor Vacuum Arc (MEVVA) ion source (IS) is a unique tool for production of high intensity metal ion beam that can be used for material surface modification. From the other hand, the duoplasmatron ion source provides the high intensity gas ion beams. The MEVVA and duoplasmatron IS developed in Institute for Theoretical and Experimental Physics were used for the reactor steel surface modification experiments. Response of ferritic-martensitic steel specimens on titanium and nitrogen ions implantation and consequent vacuum annealing was investigated. Increase in microhardness of near surface region of irradiated specimens was observed. Local chemical analysis shows atom mixing and redistribution in the implanted layer followed with formation of ultrafine precipitates after annealing.