Marek Zielinski, Marcin Kowalski, Dariusz Chaberski, Slawomir Grzelak
ESTIMATION AND PREDICTION OF THE CLOCK PHASE FLUCTUATIONS AND TIME-INTERVAL ERROR

This paper describes the new method of time-interval-error (TIE) estimation and prediction. This method is very useful for standard clocks characterization and can be applied in high precision measurement and telecommunication systems with high resolution of the time-base. TIE can be easily and fast calculated using only two parameters obtained during calibration process. Moreover, it is very simple method for clocks comparison and can be applied in time-interval measuring systems (TIMS) for calibration or TIE calculation. This method allows to calculate an accumulated jitter and TIE as a function of the clock cycles. The measurement system, specially accommodated for jitter measurements and their application for estimations or predictions of jitter parameters will be also presented and discussed.

José Manzoli, Jorge Pirolla, Eduardo Moura, Carlos Zeituni, João Moura, Maria Elisa Chuery Martins Rostelatto
RADIATION ISODOSE SURFACE DISTORTION AS A SOURCE OF DOSE OR EXPOSURE RATE MEASUREMENT UNCERTAINTY: EXAMPLE IN BRACHYTHERAPY SEEDS

Radiation sealed sources have an emission that could be studied by theirs isodose surfaces. The intersection of a plan with such a surfaces is described by the dose rate contour curves. It is very common to assume that these surfaces have rotational symmetry around the longitudinal axis, and so, the contour curves have mirror symmetries. Here it is shown, by a computational simulation, that if the radioactive material inside de sealed vessel is not homogeneous, the uncertainty in dose rate measurements could achieve high values. This uncertainty value is exemplified in a iodine-125 seed source used for brachytherapy purposes.

Jiri Pribil, B. Zatko, Ivan Frollo, F. Dubecký, Pawel Grybos
PORTABLE X–RAY CT MINI SYSTEM BASED ON MONOLITHITIC SEMI-INSULATING GAAS DETECTORS USING PERSPECTIVE IMAGING RECONSTRUCTION TECHNIQUES

The work describes the present status of development of the portable X–ray CT mini system. The system is capable to operate also as a quantum digital X–ray scanner. Detection unit is constructed from double line of 2 × 1024 SI GaAs pixel detectors with pitch of 250 µm. The system allows operation in the single photon counting regime and the energy separation (one energy window) with estimated spatial resolution higher than 125 µm. Developed modification of the X–ray image reconstruction based on perspective imaging techniques has been experimentally verified on testing phantoms and practically implemented for processing images of real test objects.

Ichirou Ishimaru, Takashi Takuma, Shinji Yabushita, Takeshi Kawajiri, Kana Yanogawa, Takaki Harada, Kazuya Yamamoto
PROPOSAL OF IMAGING-TYPE 2-DIMENSINAL FOURIER SPECTROSCOPY

We proposed the imaging-type 2-D Fourier spectroscopy that is the phase-shift interferometry between the objective lights. The proposed method can measure the 2D spectral image at the limited depth. Because of the imaging optical system, the 2D spectral images can be measured in high spatial resolution. And in the depth direction, we can get the spectral distribution only in the focal plane. In this report, we mention about the principle of the proposed imaging-type 2-D Fourier spectroscopy.

Gerd Wübbeler, Rolf Judaschke, Clemens Elster
ESTIMATION OF RESIDUAL ERROR PARAMETERS FOR VECTOR NETWORK ANALYZERS

Recently, a novel approach for the estimation of the residual error parameters of a calibrated vector network analyzer has been proposed. The method is based on a reflection measurement employing a high precision airline terminated by a short. From this measurement the complex valued residual error parameters are calculated utilizing a sophisticated data analysis scheme. In this work the uncertainty associated with the obtained residual error parameters is evaluated. The uncertainty evaluation is performed by applying the GUM S1 approach employing a Monte-Carlo method. Resulting uncertainties arising due to imperfections of the dimensional parameters of the airline are presented.