First-principles response simulation of wide-gap CdTe-DSDs for the FOXSI solar sounding rocket experiment

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Main Authors: Nagasawa, Shunsaku, Minami, Takahiro, Takahashi, Tadayuki, Watanabe, Shin
Format: Preprint
Published: 2025
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author Nagasawa, Shunsaku
Minami, Takahiro
Takahashi, Tadayuki
Watanabe, Shin
author_facet Nagasawa, Shunsaku
Minami, Takahiro
Takahashi, Tadayuki
Watanabe, Shin
contents We have developed a wide-gap CdTe double-sided strip detector (CdTe-DSD) for the fourth and fifth flights of the Focusing Optics X-ray Solar Imager sounding rocket experiment (FOXSI-4/FOXSI-5). This detector features a 30 um strip width and a variable gap width from 30 um to 70 um, enabling position resolution finer than the strip pitch by inducing charge sharing across adjacent strip electrodes and utilizing this shared energy information for position reconstruction. However, this wide-gap configuration introduces complex detector responses, such as charge loss in the gap regions and electric field distortion near the electrodes, requiring a more advanced modeling approach for interpreting observation results in FOXSI-4/FOXSI-5 and for further optimization of future detector design. To address these complexities, we have constructed a first-principles simulation framework to model the detector response. The simulation integrates Geant4-based Monte Carlo simulations of energy deposition, finite element calculations of electric and weighting fields using COMSOL Multiphysics, charge transport modeling incorporating trapping and diffusion, and calculation of the induced charge on the electrodes based on the Shockley-Ramo theorem. By introducing a surface conductive layer, which causes electric field distortion, the model successfully reproduces the experimentally observed charge loss on the cathode side. In addition, the model reproduces the distinct charge sharing behavior on the cathode and anode sides. These results validate the effectiveness of the model in characterizing the wide-gap CdTe-DSD.
format Preprint
id arxiv_https___arxiv_org_abs_2509_00738
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle First-principles response simulation of wide-gap CdTe-DSDs for the FOXSI solar sounding rocket experiment
Nagasawa, Shunsaku
Minami, Takahiro
Takahashi, Tadayuki
Watanabe, Shin
Instrumentation and Methods for Astrophysics
Solar and Stellar Astrophysics
High Energy Physics - Experiment
Instrumentation and Detectors
We have developed a wide-gap CdTe double-sided strip detector (CdTe-DSD) for the fourth and fifth flights of the Focusing Optics X-ray Solar Imager sounding rocket experiment (FOXSI-4/FOXSI-5). This detector features a 30 um strip width and a variable gap width from 30 um to 70 um, enabling position resolution finer than the strip pitch by inducing charge sharing across adjacent strip electrodes and utilizing this shared energy information for position reconstruction. However, this wide-gap configuration introduces complex detector responses, such as charge loss in the gap regions and electric field distortion near the electrodes, requiring a more advanced modeling approach for interpreting observation results in FOXSI-4/FOXSI-5 and for further optimization of future detector design. To address these complexities, we have constructed a first-principles simulation framework to model the detector response. The simulation integrates Geant4-based Monte Carlo simulations of energy deposition, finite element calculations of electric and weighting fields using COMSOL Multiphysics, charge transport modeling incorporating trapping and diffusion, and calculation of the induced charge on the electrodes based on the Shockley-Ramo theorem. By introducing a surface conductive layer, which causes electric field distortion, the model successfully reproduces the experimentally observed charge loss on the cathode side. In addition, the model reproduces the distinct charge sharing behavior on the cathode and anode sides. These results validate the effectiveness of the model in characterizing the wide-gap CdTe-DSD.
title First-principles response simulation of wide-gap CdTe-DSDs for the FOXSI solar sounding rocket experiment
topic Instrumentation and Methods for Astrophysics
Solar and Stellar Astrophysics
High Energy Physics - Experiment
Instrumentation and Detectors
url https://arxiv.org/abs/2509.00738