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A highly focusing beta spectrometer

1967; Elsevier BV; Volume: 57; Linguagem: Inglês

10.1016/0029-554x(67)90539-3

1878-3759

R. Balzer, D.S. Bharucha, F. Heinrich, Andrea Hofmann,

Spectroscopy Techniques in Biomedical and Chemical Research

The design and construction of a double focusing β-spectrometer based on the properties of a field varying as H = H0a(r sin ϑ) is described in this paper. With a choice of suitable parameters4), the characteristics of the instrument have been investigated for particles performing six trochoidal revolutions. For various initial conditions, the aberrations in the focusing and the line profile have been numerically evaluated. The calculations show that for extended sources, the instrument possesses a transmission of 1.87% which remains constant over a relatively large range of the resolution, if δpp; atδpp = 10−4, the value of the transmission amounts to 1.3%. The calculations formed the basis of the construction of a β-spectrometer having conical iron pole-pieces, maximum radius of the electron orbits being 25 cm. The experimental qualities of the spectrometer have been examined in the energy range of 75 keV to 660 keV. The results confirm the theoretical predictions to a large extent. Deviations in the value of the transmission at high resolutions can be interpreted by the disturbing effects of residual errors present in the field. The highest resolution attained has been δpp = 3.5 × 10−4; at δpp = 5 × 10−4, the value of the transmission has been measured to be 0.68%; the corresponding value of the luminosity is 2 × 10−4 cm2. The experimental results show that for δpp ≧ 5 × 10−4, this instrument possesses values of the transmission and luminosity exceeding those values of existing double focusing spectrometers.