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Purpose:Boron Neutron Capture Therapy (BNCT) is a special kind of particle therapy, based on the neutron induced fission of the boron isotope 10B [1]. We have performed dosimetry experiments on the mixed neutron and gamma fields at the TRIGA Mark II research reactor in Mainz. Commonly, dosimetry in such fields is realized by foil activation and ion chambers [2]. Here we investigate alanine as an easier and more robust alternative dosimeter.Methods:We have performed four phantom experiments at the TRIGA Mark II research reactor in Mainz [3], in a predominantly thermal neutron field with a strong gamma component. All alanine pellets irradiated are manufactured and read out at the National Physical Laboratory (NPL), United Kingdom [4]. To predict the dose and its components for each pellet, the Hansen & Olsen detector response model [5] is applied along together with FLUKA [6].Results:The measured dose response of all pellets could be reproduced by calculations within a uncertainty of 5 %. For all experiments three dose components have been separated. A proton dose is generated in the 14N(n,p)14C reaction. Secondary gammas are generated by various (n,γ) reactions, dominated by the 2.2 MeV photon from neutron capture of hydrogen. The primary gamma dose deposited originate from the reactor core itself.Conclusion:Alanine dosimeters are suitable of measurements in mixed neutron fields and the alanine response in thermal neutron fields can be fully understood by the used interpretation model. In further experiments the dosimeters will be exposed to higher neutron energies, which are more typical for BNCT treatments.References:[1] Barth, R.F; 2009: Boron neutron capture therapy at the crossroads: Challenges and opportunities. Applied Radiation and Isotopes 67, 3-6.[2] Rogus, R.D.; Harling, O.K.; Yanch, J.C.; 1994: Mixed field dosimetry of epithermal neutron beams for boron neutron capture therapy at the MITR‐II research reactor. Medical Physics 21, 1611-1626.[3] Hampel, G.; Blaickner, M.; Knorr,J.; Kratz, J.V.; Lizón Aguilar, A.; Minouchehr, S. et al.; 2009: Irradiation facility at the TRIGA Mainz for treatment of liver metastases. Applied Radiation and Isotopes 67, 238-241.[4] Sharpe, P.; Sephtan, J.; 2000: An automated system for the measurement of alanine/EPR dosimeters. Applied Radiation and Isotopes 52, 1185-1188.

The thermal column of the TRIGA reactor in Mainz is being used very effectively for medical and biological applications. The BNCT (boron neutron capture therapy) project at the University of Mainz is focussed on the treatment of liver tumours, similar to the work performed at Pavia (Italy) a few years ago, where patients with liver metastases were treated successfully by combining BNCT with auto-transplantation of the organ. Here, in Mainz, a preclinical trial has been started on patients suffering from liver metastases of colorectal carcinoma. In vitro experiments and the first animal tests have also been initiated to investigate radiobiological effects of radiation generated during BNCT. For both experiments and treatment, a reliable dosimetry system is necessary. From work elsewhere, the use of alanine detectors appear to be an appropriate dosimetry technique.

25th European Photovoltaic Solar Energy Conference and Exhibition / 5th World Conference on Photovoltaic Energy Conversion, 6-10 September 2010, Valencia, Spain; 3591-3593, The concept of the epitaxial wafer equivalent (EpiWE) is pursued at the Fraunhofer ISE as an option to reduce the cost of silicon solar cells. Within this concept, only a small amount of the expensive high purity silicon is needed for the epitaxial deposition on a low-cost substrate made from low-quality silicon. A challenging task is the control of the impurity contents in the low-grade silicon substrate. Especially transition metals like Fe, Mn, and Cr act as recombination centres and degrade the minority carrier lifetime once they diffuse into the active layer. Gettering with HCl gas is an effective and fast method to reduce the metals mentioned above to an appropriate level and can be performed prior to the epitaxial deposition. This paper presents a reduction of metal impurity concentrations up to two orders of magnitude obtained by HCl gettering of metallurgical grade (MG) and upgraded metallurgical grade (UMG) silicon. Additionally, solar cell results are shown, demonstrating the improvement of EpiWE solar cells by HCl gas gettering.

24th European Photovoltaic Solar Energy Conference, 21-25 September 2009, Hamburg, Germany; 2557-2559, In this thesis, hydrogen chloride (HCl) gas gettering of multicrystalline silicon for the use in photovoltaics is investigated. The gettering effect is due to the removal of metallic impurities from the surface of the wafers through the formation of volatile chloride compounds. This method is considered to be used as an effective purification step in the solar cell process. It could be easily integrated into the concept of the crystalline silicon thin film (cSiTF) solar cell. This concept combines two main aspects. On the one hand, it is cost saving because only a small amount of expensive high purity silicon is needed for the epitaxial deposition of a thin layer on low-cost silicon. On the other hand, the product which is called epitaxial wafer equivalent (EpiWE) can be further processed in a standard wafer cell production. However, low-cost silicon which could be used as substrate has a high amount of doping and metallic impurities which severely degrades the cell efficiency. Therefore, the amount of impurities in the substrate has to be reduced in order to prevent diffusion into the active layer. An economical and effective purification step is needed. HCl gas gettering shows the potential to achieve the required purity levels.

A new measurement of the neutron EDM, using Ramsey's method of separated oscillatory fields, is in preparation at the new high intensity source of ultra-cold neutrons (UCN) at the Paul Scherrer Institute, Villigen, Switzerland (PSI). The existence of a non-zero nEDM would violate both parity and time reversal symmetry and, given the CPT theorem, might lead to a discovery of new CP violating mechanisms. Already the current upper limit for the nEDM (|d_n, Flavor Physics & CP Violation Conference, Taipei, 2008