In the context of the project "Determination of the Relative Biological Effectiveness for high-energy, quasi-monoenergetic photon radiation" which is funded by the "Bundesamt für Strahlenschutz", the quasi-monoenergetic photon beam available at the PTB (photon energies 6...7 MeV) was calibrated in terms of the absorbed dose to water. Five samples of human blood were irradiated in this beam with...

In the frame of the annual intercomparison of personal dosimeters from the dosimetry services for neutrons it was shown, that additional irradiations with photon radiation fields do not influence the determination of the neutron dose. All irradiated albedo dosemeters fulfil the requirements.

The range of definition of the Practical Peak Voltage was extended from 150 kV to 300 kV. The definition used so far in the range from 20 to 150 kV is left untouched.

The electronic personal neutron dosemeter DOS-2002, developed at the PTB, has been successfully transferred to industry. Based on this device, a new prototype dosemeter was developed which shows an improved response to high energy neutrons and which is thus suited for neutron monitoring at high-energy accelerators.

With the aid of a water calorimeter, it was possible to determine the radiation quality correction factors k_Q for 8 MV and 16 MV photon radiation for different ionization chambers of the types NE2571 and NE2561. The standard measurement uncertainty of the experimentally determined k_Q factors is approx. 0.3% for an individual ionization chamber. Hence, it would be possible to reduce the ...

When the attenuation properties of protective X-ray clothing are measured, the scattered and fluorescence radiation generated by the protective material itself must also be completely determined in the attenuated beam. For this purpose, PTB has developed a new measurement method which - compared to the methods so far applied - is much easier to realize, gets along with smaller material samples and...

For the determination of absorbed dose to water under reference conditions at the point of measurement in a water phantom, a large transmission ionization chamber, mounted in front of the water phantom, is frequently used in the photon radiation field of a linear accelerator in order to monitor the radiation. The usual correction of the air density dependence of the response of this monitor...

Among other devices, new digital mammography facilities, whose X-ray spectra considerably differ from those of conventional facilities, are used for "mammography screening". However, the dose response of modern diagnostic dosimeters with semiconductors depends rather sensitively on the spectral shape of the X-radiation. PTB has, therefore, established new X-radiation qualities for mammography and...

Together with other partners of the Collaboration of European Low-level Underground Laboratories (CELLAR), PTB has participated for the first time in the measurement of activated metal samples from experiments at the Joint European Torus (JET). The measurement of the activation products is aimed at getting information about the spectrum of the neutrons and charged particles in the plasma.

The PTB is responsible for the conceptual design, organisation and analysis of an international key comparison for the measurement of the fluence of thermal neutrons. For this comparison transfer instruments were selected which will also yield information on the spectral distribution of the reference fields.

Environmental dosimeters must be able to measure reliably small changes of environmental radiation occurring when a radioactive cloud is passing. To examine this characteristic Department 6.3 has developed an irradiation facility with which the time dependence of the dose rate of a radioactive cloud can be simulated. To generate an increased environmental radiation two ⁶⁰Co and two ¹³⁷Cs...

Together with the National Institute of Standards and Technology (NIST), the primary standards for the realization of the unit of the absorbed dose to water for beta brachytherapy sources were compared bilaterally. The radiation field of a Sr-90/Y-90 line source as in intravascular brachytherapy was selected as comparison field. Therby, a relative difference of 4 % was found which lies within the...

Within the scope of the Euromet 909 Project, an ionization chamber of the Bulgarian national metrology institute NCM is calibrated with activity standards of PTB. The project, which covers the setting up of an automated data acquisition system, calibration and establishment of procedures for evaluation and quality control, will enable the NCM to offer calibration services for activity measurements...

At the end of the year 2005, key comparison measurements were performed between the new German primary standard for absorbed dose to water (a water calorimeter) and the primary standard for absorbed dose to water operated at the BIPM. The measurements have now been completely analyzed; the results have been published and have been entered in the key comparison database (KCDB) available at the...

On the radon standard chamber of PTB, the quantities "equilibrium factor" and "non-accumulated fraction" have for the first time been disseminated from the extreme ranges (near zero or near one) within the scope of an extensive order calibration.

An improved theoretical model now also allows activity determinations for radionuclides with electron capture at small atomic number (Z ≤30) to be performed with the aid of liquid scintillation counting. Detection probabilities determined experimentally at PTB are in good agreement with the calculation results of a program developed in Madrid. Thereby, interesting new applications, such as the...

Taking into account the geometry of the Co source and the irradiation facility the photon fluence spectrum of the PTB Co-60-reference radiation field was determined by means of radiation transport simulation. The spectrum obtained was used to calculate the depth dose curve in a water phantom, which was compared with the depth dose curve measured experimentally. Over the depth range investigated...

The novel method is based on a single airline one-port measurement which is performed with the pre-calibrated vector network analyzer. By applying a sophisticated numerical analyzing scheme to the measured broadband data set, the complexvalued residual system error parameter of the analyzer can be extracted over the entire frequency range. From the error terms, a second-order calibration of the...

The Josephson junctions with Al2O3-double barriers (SINIS junctions) used at PTB for programmable voltage standards can be damaged during the rather complex fabrication process. The reason why some critical currents strongly deviate from the average value is not known. A technological alternative are SNS junctions with only one normal conductor as effective tunnel barrier. They may reduce the...

A synthesizer for highly precise AC voltages of arbitrary waveforms is based on overdamped SNS Josephson junctions (S: Superconductor, N: Normal metal), operated by a train of short current pulses. The generated output voltage of such a Josephson Arbitrary Waveform Synthesizer (JAWS) is determined by the sequence of single pulses. The maximum pulse repetition frequency of the utilised pulse...