Modeling small diameter straw tubes in terms of their high frequency electrical characteristics

As a part of the effort to design a prototype of a low-mass tracking detector, an empirical model of the high-frequency behavior of small-diameter proportional straw tubes was developed. The equivalent circuit is a distributed network RLC-clusters, where the value of the discrete components is directly related to measurable characteristics of the em straws. The model is an approximation of the straw as a low-loss transmission line, and it yields very good agreement with measurements of transmission and reflection coefficients. Measurements and simulations of input impedance in the frequency domain agree well at frequencies below 120 MHz, when termination is close to Z₀, the characteristic impedance