E.M. Schooneveld

New silicon drift detector design for diminishing lateral diffusion

Abstract In this paper we present a new drift detector design, which diminishes the effect of lateral diffusion. This is achieved by giving the strips a saw tooth shape. In this way a small electric field in the direction parallel to the surface and perpendicular to the drift direction is established. Therefore the electrons are confined in this direction within the length of one saw tooth. The influences of some important parameters of the saw tooth are discussed.

High-purity silicon soft x-ray imaging sensor array

Abstract A 256 element soft X-ray sensor array with separate x - and y -readout addresses fabricated on high-purity silicon (4kΩ cm) utilizing only standard integrated-circuit processing technologies is presented. The design of the 16 × 16 array of 250 × 250, μm 2 elements emulates that of a successful prototype. The principle of operation of the sensor is based on both the resistive and capacitive coupling of the elements in a matrix of sensing diodes. The columnar elements are resistively coupled to one output connection through the use of highly-doped polysilicon structures, while utilization of the double-layer metalization technique provides capactive coupling of those elements lying in the same row to a separate output connection. Experimental results demonstrated good sensor characteristics and confirmed two-dimensional position detection of incident radiation with minimal crosstalk.

New Silicon Drift Detector Design With Two Dimensional Drift Time Measurement

Until now silicon dnft detectors with two dimensional position resolution made use of drift time measurement in one dimension only. The resolution in the other dimension was obtained by dividing the collecting anode into small pixels. In this paper we present a new type of drift detector that uses dnft time measurements for both dimensions. The design consists of concentric quadrilateral closed strips with a small collecting anode in the centre. At first electrons will travel perpendicular to the strips until they reach a &agonal. Then they will proceed along this diagonal until they are collected at the centre. Position resolution in two hmensions can be obtained when both the time the electrons need to reach the &agonal and the time they need to reach the centre are measured. The latter is obtained from the collecting anode, the former from a diagonal strip present at the back side of the detector. Compared to common 2D drift detectors this detector offers the advantage of a small amount of read out electronics. It also has the advantage of having just one small collecting anode with a very low capacitance, resulting in low noise and therefore in a good energy resolution.

Integrating transistors on high-ohmic silicon

Abstract This paper presents a compatible technology for integrating both radiation detectors and transistors on the same high-ohmic silicon substrate. Using this technology, chips have been fabricated containing a number of test transistors (MOSFETs) with different geometries. Measurements on the devices showed a threshold voltage between 0 and -3 V, and a transconductance between 25 μA/V and 1.25 mA/V for aspect ratios between 0.7 and 50, respectively. The results demonstrate that transistors can be integrated together with radiation detectors onto one chip, which can lead to radiation detectors containing both detecting elements and signal-modification units, such as preamplifiers and multiplexers.

New ideas for two dimensional position sensitive silicon drift detectors

In this paper we present two new ideas for drift detectors with two dimensional position resolution. The first idea is based on the regular drift detector, but has a slightly different design in order to deal with diffusion problems. The second idea embodies a completely new type of drift detector that uses drift time measurements for both dimensions. The design consists of concentric quadrilateral closed strips with a small collecting anode in the centre. At first electrons travel perpendicular to the strips until they reach a diagonal. Then they proceed along this diagonal until they are collected at the centre. Position resolution in two dimensions can be obtained when both the time the electrons need to reach the diagonal and the time they need to reach the centre are measured. The latter is obtained from the collecting anode, the former from a diagonal strip present at the back side of the detector. Compared to common 2D drift detectors this detector offers the advantage of a small amount of read out electronics. It also has the advantage of having just one small collecting anode with a very low capacitance, resulting in low noise and therefore in a good energy resolution. >

A silicon detector for DNA-sequencing

Abstract Silicon detectors have been proven to be useful in β-radiochromatography and DNA-sequencing because of their good spatial resolution and high detection efficiency. In DNA-sequencing the demands for a fast and accurate detection system are growing. Our group has made a prototype detection system for DNA-sequencing based on a two-dimensional position sensitive silicon detector. The experimental setup and readout electronics will be described. The results of test measurements performed in collaboration with the Biochemistry group of the Department of Biochemistry of the University of Leiden will be presented.

A silicon detection system for DNA-sequencing

Abstract Nowadays in DNA-sequencing the position of the radioactive bands, which represents the structure of the DNA molecule, is determined by using X-ray films. By using silicon position sensitive detectors, these measurements can be speeded up and the analysis be automated. In this article we present the experimental setup and the readout electronics of a new detection system for DNA-sequencing. The detector and readout electronics have been tested separately, and operate satisfactorily. The detection system has not been tested, because the detector and readout electronics are not assembled yet.

A new NdFe loaded polarimeter for electron and photon polarimetry at higher energies

The new NdFe polarimeter aims at photon, electron and positron polarimetry at energies up to 200 MeV. Spin dependent Compton, Moller or Bhabha scattering in magnetised NdFe layers can be recognised by means of position sensitive silicon sensors. Theoretical studies showed that the figure of merit of this polarimeter is much better compared to that of others. Tests of the silicon vertex detection system have shown satisfactory results. The polarimeter will be described and results of the longitudinal polarisation measurements of electrons will be presented.<<ETX>>

Results of a new silicon drift detector design for diminishing lateral diffusion

Previously we introduced a new drift detector design, that diminishes the effect of lateral diffusion. This is achieved by giving the strips a saw tooth shape. In this way a small electric field in the direction parallel to the surface and perpendicular to the drift direction is established. Therefore the electrons are confined within the length of one saw tooth. In this paper we describe the design and fabrication of these detectors, as well as some measurements.<<ETX>>

Study of the position-sensitive detection of X-rays with a silicon drift chamber

Abstract A silicon drift chamber (SDC) is an attractive device for the position-sensitive detection of low-energy radiation. In case of X-ray detection the start signal has to be generated internally. Results of computer simulations are presented showing that in a p-type SDC the influence of the variation in the rise time of the start signal on the position resolution is much smaller than in an n-type SDC. Furthermore, calculations show that in both cases, the noise contribution to the position resolution is much more important. Again in a p-type detector the influence of the noise is smaller than in an n-type SDC. The conclusion seems justified that for position-sensitive detection of X-rays the use of a p-type SDC is preferable.