S. Kalbitzer

On the charge dividing mechanism in position sensitive detectors

The principle of operation of the one dimensional position sensitive detector is investigated by means of a simple model describing the detector as a line of a continuously distributed junction capacitance C and resistance R of the back layer. It is shown that a linear relationship exists between the position of the incident particle and the total charge collected at the position contact of the detector. The kinetics of the charge collected at the position and energy contact were computed. The rise times of the charge pulses (10–90%) are found to vary with the position of incidence up to about RC/4 sec.

On the ballistic deficit and the signal-to-noise ratio of semiconductor spectrometers for energy and position spectroscopy

Abstract The ballistic deficit and the signal-to-noise ratio of one dimensional position sensitive detectors are investigated by means of a simple model describing the detector as a line of a continuously distributed junction capacitance C and resistance R of the back layer. R has an upper limit, if the variation of the ballistic deficit for particles incident on different positions has been given a fixed value. On the other hand low values of the resistance of the back layer cannot be tolerated because of serious noise problems. Thus a compromise was found between these two conflicting aspects allowing a sufficiently small variation of the ballistic deficit and a resonable resolution of the position and energy signal. In a typical case, e.g. C = 150 pF, R = 7.8 k Ω , equivalent noise resistance of the preamplifier Req = 250 ohm and using RC-integration and single delay line differentiation of 0.7 μsec, the variation of the ballistic deficit is less than 1%, the energy resolution 26 keV fwhm Si and the position resolution 44 keV fwhm Si. For a 50 mm long detector and 5.5 MeV particles the position resolution corresponds to 0.4 mm fwhm Si.

Range parameters of heavy ions in amorphous targets at LSS-energies of 0.0006⩽ ϵ ⩽ 0.3

Abstract Heavy ions of various elements have been implanted into amorphous silicon, germanium and aluminum layers at energies of 1–60 keV. High resolution ion backscattering has been used to determine range parameters and nuclear stopping powers.

Evidence for an insulator—metal effect on the Z1 range oscillations in the nuclear stopping regime

Abstract Z1 oscillations of the range of low-energy heavy ions, of up to ±25% with respect to a universal range—energy curve, have been observed for the semiconductors Si and Ge, but not for the metals Al, Ti and Ni.

Nuclear and electronic stopping powers of low energy ions with Z ⩽ 10 in silicon

Abstract Specific energy losses of H, He, B, C, N and Ne ions have been measured in silicon in the energy range from 2 keV to 60 keV, by using ion implanted, thin window silicon detectors. Chopped ion currents and lock-in amplification techniques were applied to avoid the problems of low signal-to-noise ratios. Both electronic and nuclear stopping powers have been measured. Comparison with LSS-theory is made.

An X−Y position sensitive detector

Abstract By implanation of boron resp. phosphorus ions into n-type silicon p+-n-n+ junction detectors were produced. The p+ and n+ resistive layers served to provide X and Y information of the position of incidence of ionizing particles.

Range parameters of protons in silicon implanted at energies from 0.5 to 300 keV

Abstract We used the 6.4 MeV resonance of the reaction 1H(15N, αγ)12C to determine the moments of the hydrogen distributions in silicon. The distributions were obtained by implantations of about 1016 H/cm2 at energies from 0.5 to 300 keV intto amorphized silicon. It was found that an analytic description of the depth profiles can be given by the Edgeworth distribution. The first four moments of this distribution were determined by fitting the experimental curves using standard least-square techniques. The results are compared with experimental data and with calculations based on the LSS theory. By using theoretical factors for the conversion of the projected to full ranges the stopping powers were derived and compared with tabulated values.

Range parameters of heavy ions at 10 and 35 keV in silicon

Projected ranges and range straggling of Ge- and As-ions with LSS-energies of ϵ < 0.2 have been measured with backscattering techniques using a high resolution electrostatic analyzer.

Measurement of ultra-thin windows of ion implanted silicon detectors with low energy proton beams

Abstract Silicon particle detectors have been fabricated by implantation of boron ion of keV-energies. Window thicknesses were derived from the variation of the detector current level with the angle of the incident proton beam. The precission of the measurements is about ±20 A . The thinnest window obtained so far is 340 A (Si).

A nomogram for the design of position sensitive silicon detectors

Abstract The charge dividing mechanism of a position sensitive detector can be understood by the simple model of a one dimensional RC -line. When this network is extended to the more realistic two dimensional case, the charge dividing properties are found to remain unaltered. It is shown that the positional information is correlated with the center of gravity of the initial charge distribution. The most relevant electrical parameters which determine resolution and ballistic deficit have been evaluated and are presented in a nomogram.