Modelling and 3D optimisation of CdTe pixels detector array geometry – Extension to small pixels

Zumbiehl, A.; Hage‐Ali, M.; Fougères, P.; Koebel, J.M.; Regal, R.; Rit, C.; Ayoub, M.; Siffert, P.

doi:10.1016/s0168-9002(01)00771-9

Cited by 19 publications

(15 citation statements)

References 12 publications

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“…9). The optimal pixel size is a compromise between the pixel effect and its drawback (mainly electron trapping) [5]. The decreasing electric field gives better resolutions for small pixels, as expected, while the uniform one is better when the pixel effect decreases (higher pixel sizes).…”

Section: B 3-d Monte Carlo Simulationmentioning

confidence: 52%

“…Previous studies ( [5], [6], [16]) propose different functions to describe the weighting potential. Nevertheless, the weighting potential function cannot be a simple one.…”

Section: Energy Resolution Calculationmentioning

confidence: 99%

“…For (our measurement), the improvement is in the order of 30-40%. This drastic improvement can be explained by considering the drawback of the pixel effect: the loss of the electrons that do not reach the pixel [5]. With the pixel effect, the signal is mainly induced by the electrons moving, that removes the hole contribution.…”

Section: B Non-uniform Electric Fieldmentioning

confidence: 99%

“…The final 3-D compound charge carrier distribution is calculated by a complete Monte Carlo simulation described in a previous paper, especially with the evaluation of the 3-D weighting potential by Fourier series [5]. Noise contribution, both charge carrier trapping and lateral diffusion are taken into account.…”

Section: B 3-d Monte Carlo Simulationmentioning

confidence: 99%

“…In detectors with segmented electrodes, the pixel effect [3], [4] can compensate the poor hole transport properties, one of the main weakness of these materials, and the use of monolithic detector array is well adapted for more uniform imaging (non uniformity is the other main weakness). Several studies have been done on the pixel effect, e.g., [5]. However, for nuclear detection, the shape of the electric field is frequently neglected, i. e. considered uniform, or with minor effects.…”

Section: Introductionmentioning

confidence: 99%

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Why a Real Non-Uniform Electric Field in Nuclear Detector Arrays Can Improve the Energy Resolution

Zumbiehl

Hage‐Ali²

2007

IEEE Trans. Nucl. Sci.

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Owing to their intrinsic properties, nuclear imaging systems based on room temperature semiconductor materials are still the topic of numerous research and development schemes. Due to their high atomic number and their high resistivity, CdTe and CdZnTe (CZT) have been used extensively in these systems, especially for astrophysics and medical applications. However, the shape of the electric field has always been poorly considered, i.e., assumed uniform, or with minor implications on gamma-ray spectra-and this is far from the real situation. Consequently, real electric field profiles measured by Pockels effect are presented in this work. Furthermore, we develop a formalism integrating non-uniform electric field profiles. Results are presented in term of energy resolution, which is of utmost importance in nuclear imaging, mainly for counting efficiency and contrast. Finally, the analytical results are completed and confirmed with Monte Carlo simulations. Contrary to generally accepted ideas, a real and non-uniform decreasing electric field can improve the energy resolution, especially for thick detector arrays. Therefore in "classical" simulations of nuclear detection the value of the parameter , which represents the charge transport properties, is excessive to "agree with the experimental data". This work gives an answer to this incoherence, and finally shows that realistic nuclear detection results can be simulated with realistic values and non-uniform electric field, with an example of geometrical optimization.

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Section: B 3-d Monte Carlo Simulationmentioning

confidence: 52%

“…Previous studies ( [5], [6], [16]) propose different functions to describe the weighting potential. Nevertheless, the weighting potential function cannot be a simple one.…”

Section: Energy Resolution Calculationmentioning

confidence: 99%

Section: B Non-uniform Electric Fieldmentioning

confidence: 99%

Section: B 3-d Monte Carlo Simulationmentioning

confidence: 99%