P06.06 Enhancing trafficking and resistance to immunosuppression of synthetic agonistic receptor-transduced T cells in solid tumor models

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Determination of impurity distributions in ingots of solar grade silicon by neutron activation analysis

In a series of crystallization experiments, the directional solidification of silicon was investigated as a low cost path for the production of silicon wafers for solar cells. Instrumental neutron activation analysis was employed to measure the influence of different crystallization parameters on the distribution of 3d-metal impurities of the produced ingots. A theoretical model describing the involved diffusion and segregation processes during the solidification and cooling of the ingots could be verified by the experimental results. By successive etching of the samples after the irradiation, it could be shown that a layer of at least 60 μm of the samples has to be removed to get real bulk concentrations

Instrumental determination of phosphorus in silicon for photovoltaics by β spectroscopy: A new approach

In this study, we report on the investigation of a β-γ-anticoincidence set up for the determination of phosphorus in silicon for photovoltaics by Instrumental Neutron Activation Analysis. For the suppression of disturbing β/γ radiation emitted by impurities, a plastic scintillator for β-detection is surrounded by a well type NaI(Tl) γ-detector. A suppression of 40 % for the impurities 60Co and 124Sb could be achieved. The limit of detection was determined to be less than 0.1 ppm. In order to correct different β absorption, dedicated Geant4 simulations were used. With first quantitative measurements the phosphorus concentration in silicon could be determined

Determination of boron and hydrogen in materials for multicrystalline solar cell production with prompt gamma activation analysis

For the optimization of the manufacturing process of multicrystalline silicon (mc-Si) for solar cells in order to reduce energy consumption and costs, it is important to know the distribution of the impurities. In our project, we analyzed the raw materials, the crucibles, and the solidified blocks (ingots) with different methods based on neutron activation. In this paper, we present the technique and the results of the boron and hydrogen determination with prompt gamma activation analysis (PGAA). We show that the distribution of boron in the ingots can be successfully described with a Scheil curve. Concerning the raw material, the most relevant information is the average elemental mass fraction. For this purpose, PGAA is well suited since it provides a bulk analysis with detection limits down to the low ng/g range for boron and µg/g range for hydrogen. In this context, the hydrogen content of fluidized bed reactor (FBR) feedstock is discussed in detail. These were the first extensive PGAA studies of the boron and hydrogen content in mc-Si