[en] Degenerate n-type InSb and InAs specimens are irradiated with fast reactor neutrons at a temperature below 6 K. The flux of thermal neutrons at the sample position is suppressed by a Cd and In shielding in order to avoid any transmutation doping. The transport properties of the irradiated semiconductors are studied by means of resistivity and Shubnikov-de Haas effect measurements. An isochronal annealing program in the temperature range up to 350 K is performed subsequent to the irradiation. From the analysis of the conduction electron density, the transport scattering rate, and the inverse lifetime of the Landau levels it is concluded that in InSb a considerable annealing is possible at room temperature, whereas in InAs no major recovery is observed. The effect of fast neutron induced defects on the feasibility of neutron transmutation doping in InSb and InAs is discussed. (orig.)

[en] The positive magnetoconductivity Δσ(B) of InP near the metal-insulator transition (MIT) was measured as a function of the conduction electron concentration and the compensation ratio. Starting deep within the metallic regime the charge carrier density of the sample was reduced stepwise below the critical value of the MIT by fast neutron irradiation due to the acceptor-like nature of the irradiation defects. Up to being exposed to a fast neutron dose of Φt_f 1.4 x 10¹⁶cm^-2 the sample behaved in a metallic fashion, and subsequent to each irradiation step the inelastic scattering time was deduced from the slope of the Δσ = f(B²) curves in the temperature range 2K < Τ < 6K. The temperature dependence of the inelastic scattering time was found to vary as T^-1, in agreement with a previous theory. After the radiation-induced crossover into the insulating regime the Δσ ∝ B² dependence was still observed. In this case the temperature dependence of the negative magnetoresistance was of the form Δρ/ρ ∝ Τ^-α with α 1.26. The influence of the compensation ratio on the measured properties is discussed. (author)

[en] Due to its design as a heavy water moderated reactor with a very compact core FRM II, Germany's most modern and most powerful research reactor, offers excellent conditions for basic research using beam tubes. On the other hand it is equipped with various irradiation facilities to be used mainly for industrial purposes. From the very beginning of reactor operation a dedicated department had been implemented in order to provide a neutron irradiation service to interested parties on a commercial basis. As of today the most widely used application is Si doping. The semiautomatic doping facility accepts ingots with diameters between 125 mm and 200 mm and a maximum height of 500 mm. The irradiation channel is located deep in the heavy water tank and exhibits a ratio of thermal/fast neutron flux density of > 1000. This value allows the doping of Si to a target resistivity as high as 1100 Ωcm within the tight limits regarding accuracy and homogeneity specified by the customer. Typically the throughput of Si doped in FRM II sums up to about 15 t/year. Another topic of growing importance is the use of FRM II aiming the production of radioisotopes mainly for the radiopharmaceutical industry. The maybe most challenging example is the production of Lu-177 n. c. a. based on the irradiation of Yb₂O₃ to a high fluence of thermal neutrons of typically 1.5E20 cm^-2. The Lu-177 activity delivered to the customer is in the range of 750 GBq. With respect to further processing it turned out to be a highly advantageous to have the laboratories of ITG, the company extracting the Lu-177 from the freshly irradiated Yb₂O₃ on site FRM II. Further irradiation facilities are available at FRM II in order to allow the activation of samples for analytical purposes or to irradiate samples for geochronological investigations using the fission track technique. Finally a project on the future installation of a facility dedicated to the irradiation of U-targets for the production of Mo-99 is in progress. It is noteworthy that all of the irradiation facilities at FRM II have been certified according to the ISO 9001:2008 standard

[en] The new research reactor FRM-II in Garching became critical for he first time on March 2nd, 2004. In the following start-up procedure the thermal power was increased stepwise for a large test program in safety and performance including secondary sources and experimental facilities. The nominal power was reached in August 2004 and the end of the first full cycle in October 2004. The result of this successful start-up procedure is reported here. (author)

[en] n-type InSb single crystals were irradiated with thermal neutrons below T = 6 K. The Shubnikov-de Haas effect and the resistivity ρ(T = 4.6 K) were measured as a function of the neutron dose and the holding temperature of a subsequent annealing program. The results are discussed in terms of the transport scattering rate and the lifetime of the Landau-levels. They have to be interpreted by means of n-doping due to nuclear reactions and irradiation induced negatively charged defects. Almost complete annealing of the transport parameters can be achieved by heating the samples to T_A = 400 K. (author)

[en] Degenerate InAs single crystals have been irradiated by thermal neutrons below 6 K. The Shubnikov-de Haas effect and the electrical resistivity have been measured as a function of the neutron dose and the annealing temperature. The effects of transmutation doping and simultaneous introduction of lattice defects have been analysed in terms of the conduction electron density and the scattering rates τ_ρ^-1 - ρne²/m^* and τ_x^-1 2πkub(B)X/h/2π (where X is the Dingle temperature). The measured conduction electron density after irradiation and thermal annealing agreed well with the values calculated from the experimental and materials parameters. The effects of radiation damage may qualitatively be explained assuming neutral In vacancies to be the most common type of defect in thermal-neutron-irradiated InAs. A comparison with similar experiments on InSb is given. (author)

[en] In Garching near Munich the Technische Universitaet Muenchen is building the 'Forschungsreaktor Muenchen' (FRM-II), a new multi purpose research reactor which will be operated at 20 MW thermal power. Although the main task of this reactor will be to provide experimental setups for beam tube applications it will be equipped with a variety of irradiation facilities which will be available for interested parties from research institutes and industry. The main design feature of the FRM-II is its very small reactor core ('compact core'). The single fuel element will be cylindrically shaped. More precisely it will consist of 113 fuel plates being bent to involute shape and welded between 2 concentric tubes having an inner diameter of 118 mm and an outer one of 243 mm. The height of the fuel zone will be 700 mm. It will contain approximately 8 kg of high density uranium-silicide fuel with an U-235 enrichment of 93%. The reactor core will be cooled by light water. The fission neutrons will be moderated, however, within a heavy water tank surrounding the core. It is the most important advantage of this design that the maximum of the thermal neutron flux density will be located outside the reactor core within the moderator tank. Consequently it will be available for experimental purposes. Its numerical value was calculated to be 8x10¹⁴cm^-2 s^-1 for undisturbed conditions

[en] A computerized photon attenuation data base has been developed by the NBS Photon and Charged Particle Data Center for the photon energy range 10 eV to 100 GeV and for elements, with Z = 1 to 94. An example of use of this data base in the critical evaluation of a theory-based data-set is presented. (Auth.)

[en] Within the framework of the Large Hadron Collider (LHC) R ampersand D programme, CERN and the Department of Physics E21 of the Technical University Munich have established a collaboration to carry out irradiation experiments at liquid helium and liquid nitrogen temperatures on epitaxial diodes for the superconducting magnet protection. Small diode samples of 10 mm wafer diameter from two different manufacturers were submitted to doses of up 50 kGy and neutron fluences up to 1015 n/cm² and the degradation of the electrical characteristics was measured versus dose. During irradiation the diodes were submitted to current pulse annealing and after irradiation to thermal annealing. After exposure some diodes show a degradation in forward voltage drop of up to 600 % which, however, can be reduced to about 15 % - 20 % by thermal annealing. The degradation at liquid helium temperature is very similar to the degradation at liquid nitrogen temperature. These degradations of electrical characteristics during the short term irradiation in a nuclear reactor are compared with degradations during long term irradiation in an accelerator environment at liquid nitrogen temperature

[en] The shear strengths of various fibre reinforced resins being promising candidate insulators for superconducting coils to be used tinder a strong radiation load, e.g. in future fusion reactors were investigated prior and subsequent to reactor in-core irradiation at liquid helium temperature. A large number of sandwich-like (steel-bonded insulation-steel) specimens representing a widespread variety of materials and preparation techniques was exposed to irradiation doses of up to 5 x 10⁷ Gy in form of fast neutrons and γ-radiation. In a systematic study several experimental parameters including irradiation dose, postirradiation storage temperature and measuring temperature were varied before the determination of the ultimate shear strength. The results obtained from the different tested materials are compared. In addition an upgrade of the in-situ test rig installed at the Munich research reactor is presented, which allows combined shear/compression loading of low temperature irradiated specimens and provides a doubling of the testing rate