Detector Spectral Response Research Articles

Constrained one-step material decomposition reconstruction of head CT data from a silicon photon-counting prototype.

Spectral CT material decomposition provides quantitative information but is challenged by the instability of the inversion into basis materials. We have previously proposed the constrained One-Step Spectral CT Image Reconstruction (cOSSCIR) algorithm to stabilize the material decomposition inversion by directly estimating basis material images from spectral CT data. cOSSCIR was previously investigated on phantomdata. This study investigates the performance of cOSSCIR using head CT datasets acquired on a clinical photon-counting CT (PCCT) prototype. This is the first investigation of cOSSCIR for large-scale, anatomically complex, clinical PCCT data. The cOSSCIR decomposition is preceded by a spectrum estimation and nonlinear counts correction calibration step to address nonideal detectoreffects. Head CT data were acquired on an early prototype clinical PCCT system using an edge-on silicon detector with eight energy bins. Calibration data of a step wedge phantom were also acquired and used to train a spectral model to account for the source spectrum and detector spectral response, and also to train a nonlinear counts correction model to account for pulse pileup effects. The cOSSCIR algorithm optimized the bone and adipose basis images directly from the photon counts data, while placing a grouped total variation (TV) constraint on the basis images. For comparison, basis images were also reconstructed by a two-step projection-domain approach of Maximum Likelihood Estimation (MLE) for decomposing basis sinograms, followed by filtered backprojection (MLE + FBP) or a TV minimization algorithm (MLE + TVmin ) to reconstruct basis images. We hypothesize that the cOSSCIR approach will provide a more stable inversion into basis images compared to two-step approaches. To investigate this hypothesis, the noise standard deviation in bone and soft-tissue regions of interest (ROIs) in the reconstructed images were compared between cOSSCIR and the two-step methods for a range of regularization constraintsettings. cOSSCIR reduced the noise standard deviation in the basis images by a factor of two to six compared to that of MLE + TVmin , when both algorithms were constrained to produce images with the same TV. The cOSSCIR images demonstrated qualitatively improved spatial resolution and depiction of fine anatomical detail. The MLE + TVmin algorithm resulted in lower noise standard deviation than cOSSCIR for the virtual monoenergetic images (VMIs) at higher energy levels and constraint settings, while the cOSSCIR VMIs resulted in lower noise standard deviation at lower energy levels and overall higher qualitative spatial resolution. There were no statistically significant differences in the mean values within the bone region of images reconstructed by the studied algorithms. There were statistically significant differences in the mean values within the soft-tissue region of the reconstructed images, with cOSSCIR producing mean values closer to the expectedvalues. The cOSSCIR algorithm, combined with our previously proposed spectral model estimation and nonlinear counts correction method, successfully estimated bone and adipose basis images from high resolution, large-scale patient data from a clinical PCCT prototype. The cOSSCIR basis images were able to depict fine anatomical details with a factor of two to six reduction in noise standard deviation compared to that of the MLE + TVmin two-stepapproach.

GPU-accelerated CZT detector simulation with charge build-up effects

The simulation of semiconductor detectors is a key tool for developping and studying their behavior. In general, simulations of CZT detectors assume the crystal to be perfect, meaning that its properties are uniform. However, structural defects appearing in the crystal during growth modify these properties. Moreover, dynamic phenomena like polarization can appear. In particular, the electric field inside the detector can be disturbed by bulk charges, which creates uncertainties on measurement of incident photon energy and on interaction position estimated by sub-pixel positioning. One of the main issues of a simulation considering these non-uniformities is its complexity, especially if multiple or evolving electric field distributions have to be considered. Hence, we have developed a model accepting electric field modifications and allowing to observe quickly the detector's response modifications with the electric field. We leveraged GPU to address such computational burden. Indeed, we can afford to consider more complex simulations as the computation time is reduced. In this study, we introduced different types of spatial defects which may be found in real CZT crystals (point-like, planar, etc.) to observe quickly and easily their impact on the detector's measurement, on both spatial and spectral response.

Photon-counting CT via interleaved/gapped spectral channels: Feasibility and imaging performance.

Compared to energy integration, photon-counting x-ray detection facilitates the spectral channelization (energy binning) in spectral CT and thus offers the opportunity to implement data acquisition via sophisticated schemes, for example, gapping or interleaving in spectral channels. In this article, we report our investigation of the performance of material decomposition based spectral imaging in photon-counting CT implemented in such data acquisition schemes, and their comparison with the benchmark scheme and other schemes without spectral gapping or interleaving. Using a deliberately designed anthropomorphic head phantom that mimics the intracranial soft tissues and bony structures, a simulation study is carried out with the focus on two-material decomposition based spectral imaging in photon-counting computed tomography (CT), under both ideal and realistic detector spectral responses. The projection data are acquired in four spectral channels, and then are sorted to implement the schemes of gapping ((ch1 , ch3 ); (ch2 , ch4 ); (ch1 , ch4 )) and interleaving ((ch1 , ch3 ) + (ch2 , ch4 ); (ch1 , ch4 ) + (ch2 , ch3 ); ((ch1 + ch3 ), (ch2 + ch4 )); ((ch1 + ch4 ), (ch2 + ch3 ))) in spectral channels, in addition to the benchmark scheme ((ch1 + ch2 ), (ch3 + ch4 )) and other conventional schemes (ch1 , ch2 ), (ch2 , ch3 ) and (ch3 , ch4 ), where ''ch'' denotes channel, ''+'' denote addition, and (·,·) the operation of material decomposition and image reconstruction. Using the contrast-to-noise ratio between targeted regions of interest as the figure of merit, we study the performance of spectral imaging (material specific and virtual monochromatic) associated with these spectral channelization schemes. Under ideal detector spectral response, the scheme (ch1 , ch4 ) outperforms the benchmark scheme ((ch1 + ch2 ), (ch3 + ch4 )) and others in gapped and/or interleaved spectral channelization in material specific imaging, while the interleaved scheme (ch1 , ch4 ) + (ch2 , ch3 ) performs the best in virtual monochromatic imaging. Notably, only about half x-ray dose is utilized in the scheme (ch1 , ch4 ) for image formation. Under realistic detector spectral response, the difference in imaging performance over all spectral channelization schemes diminishes, along with degradation in each scheme's individual performance. The results suggest that (i) different strategy in spectral channelization may have to be exercised in material specific imaging and virtual monochromatic imaging, respectively, and (ii) the spectral distortion in realistic detector's response due to charge-sharing, Compton scattering, and fluorescent escaping should be mitigated as much as possible. The spectral channelization schemes and associated imaging performance reported herein are novel and thus informative to the community, which may further the understanding of physical fundamentals and design principles for material decomposition based spectral imaging in photon-counting CT and other x-ray related imaging modalities.

Deconvolution of SNPP VIIRS Solar Diffuser Bidirectional Reflectance Distribution Function On-Orbit Change Factor

The earth-observing visible infrared imaging radiometer suite (VIIRS) on the Suomi National Polar-orbiting Partnership (SNPP) satellite regularly calibrates its reflective solar bands (RSBs), primarily through observing an onboard sunlit solar diffuser (SD). The on-orbit change of the value of the SD bidirectional reflectance distribution function (BRDF) is quantified by a numerical factor, called the H-factor, and is determined by the onboard SD stability monitor (SDSM). Because the spectral response function of an SDSM detector spreads in wavelength, the directly measured H-factor is the true H-factor convolved with the spectral response function. To find the true H-factor, we use the traditional direct method and an innovative iterative approach to separately deconvolve the measured H-factor. Our iterative approach relies on two properties of the SDSM detector spectral response function: the central peak width is narrow enough so that the H-factor does not change much over the peak width, and the dominance of the spectral response function’s integral with respect to the wavelength over the width. The iterative approach is more accurate, of a smaller noise impact, much more flexible in terms of interpolation and extrapolation of functional values, and faster. We have used deconvolved H-factors to calibrate the NASA SNPP VIIRS RSB Collections 1 and 2 Level-1B products.

On the Conditioning of Spectral Channelization (Energy Binning) and Its Impact on Multi-Material Decomposition Based Spectral Imaging in Photon-Counting CT

The conditioning (well-posedness) of basis materials (functions) and spectral channelization play important roles in determining the performance of spectral imaging (material specific imaging and virtual monochromatic imaging/analysis) in photon-counting CT. Aimed at further understanding the fundamentals of photon-counting spectral CT and providing guidelines on its design and implementation, we propose a singular value decomposition (SVD) and analysis based approach in this work to assess the conditioning of spectral channelization and its impact on the performance of spectral imaging under both ideal and realistic detector spectral response. Via simulation studies, in which the geometry of photon-counting CT is similar to a clinical CT, the condition number acquired via SVD and analysis is employed to assess the conditioning of spectral channelization in photon-counting CT and its impact on the performance of spectral imaging. The simulation study runs over two- and three-material decom-position based spectral imaging (material specific imaging and virtual monochromatic imaging/analysis over the energy range [18] [150] keV). Under both ideal and realistic detector spectral response, a specially designed phantom that mimics the soft and bony tissues in the head is utilized to quantitatively reveal the relationship between the conditioning (condition number) of spectral channelization and the performance (mainly noise and contrast-to-noise ratio) of spectral imaging in photon-counting CT. The simulation study is also extended over the cases wherein up to 50% spectral overlapping occurs. The results show that, under ideal detector spectral response, the condition number of spectral channelization reaches the minimum while no overlapping occurs in spectral channels. The condition number of spectral channelization increments with increasing spectral overlapping in the channels. The distortion in detector's spectral response induced by scattering, charge-sharing and fluorescent escaping results in spectral overlapping in spectral channels and thus degrades the conditioning (larger condition number) of spectral channelization. Respectively, the noise increases and contrast-to-noise ratio decreases in material- specific imaging and virtual monochromatic imaging/analysis, while the condition number of spectral channelization increments with increasing spectral overlapping. The SVD and analysis based approach can be utilized to systematically analyze the conditioning of spectral channelization and its impact on the performance of spectral imaging in photon-counting CT. The approach proposed by us brings innovation and has significance. In addition to providing information for insightful understanding of the fundamentals, the approach proposed in this study and the data obtained so far may provide guidelines on the implementation of spectral imaging in photon-counting CT and energy-integration CT as well, along with its applicability to other x-ray related imaging modalities such as radiography and tomosynthesis.

Plasmonic-Layered InAs/InGaAs Quantum-Dots-in-a-Well Pixel Detector for Spectral-Shaping and Photocurrent Enhancement.

The algorithmic spectrometry as an alternative to traditional approaches has the potential to become the next generation of infrared (IR) spectral sensing technology, which is free of physical optical filters, and only a very small number of data are required from the IR detector. A key requirement is that the detector spectral responses must be engineered to create an optimal basis that efficiently synthesizes spectral information. Light manipulation through metal perforated with a two-dimensional square array of subwavelength holes provides remarkable opportunities to harness the detector response in a way that is incorporated into the detector. Instead of previous experimental efforts mainly focusing on the change over the resonance wavelength by tuning the geometrical parameters of the plasmonic layer, we experimentally and numerically demonstrate the capability for the control over the shape of bias-tunable response spectra using a fixed plasmonic structure as well as the detector sensitivity improvement, which is enabled by the anisotropic dielectric constants of the quantum dots-in-a-well (DWELL) absorber and the presence of electric field along the growth direction. Our work will pave the way for the development of an intelligent IR detector, which is capable of direct viewing of spectral information without utilizing any intervening the spectral filters.

Monolithically fabricated tunable long-wave infrared detectors based on dynamic graphene metasurfaces

Here, the design, fabrication, and characterization of an actively tunable long-wave infrared detector, made possible through direct integration of a graphene-enabled metasurface with a conventional type-II superlattice infrared detector, are reported. This structure allows for post-fabrication tuning of the detector spectral response through voltage-induced modification of the carrier density within graphene and, therefore, its plasmonic response. These changes modify the transmittance through the metasurface, which is fabricated monolithically atop the detector, allowing for spectral control of light reaching the detector. Importantly, this structure provides a fabrication-controlled alignment of the metasurface filter to the detector pixel and is entirely solid-state. Using single pixel devices, relative changes in the spectral response exceeding 8% have been realized. These proof-of-concept devices present a path toward solid-state hyperspectral imaging with independent pixel-to-pixel spectral control through a voltage-actuated dynamic response.

Stellar Instrument Magnitude Estimation in Infinite-Dimensional Space

The guide star catalog generation is based on the estimation of stellar instrument magnitudes and the performance and the reliability of star identification algorithms can also be improved by this estimation. This task is critical for the design of advanced star sensors. In this study, a novel method for estimating stellar instrument magnitudes is presented. In this method, the functions of the star illuminance and spectral responsivity of detectors are considered infinite-dimensional vectors in Hilbert space, where the model between star illuminance and magnitudes in each band is established. All feasible solutions for star illuminance that meet the corresponding magnitudes in a band are considered curves in infinite-dimensional space. Accordingly, the solution for star illuminance as the intersection of curves originating from magnitudes in multiple bands can be calculated by solving the corresponding redundant equations. Then, stellar instrument magnitudes can be obtained. An optimization algorithm with limited step lengths and directions that can accurately and quickly solve the problem is proposed and applied to effectively solve the aforementioned equations. An error model is also established in infinite-dimensional space to minimize estimation error, and an optimal band selection rule used in the redundant equations is provided. A simulation experiment is conducted, and its RMSE is 11% lower than the best existing approach. In addition, the night sky experiment performed in this study demonstrates that the proposed method cannot only guarantee accuracy but can also adapt to a wide spectral range.

Numerical simulation study of a high efficient AlGaN-based ultraviolet photodetector

In this paper, a two-dimensional (2D) numerical simulation study of a p+-n-n+ AlGaN-based ultraviolet (UV) photodetector, which is designed to achieve true solar blindness with a cutoff wavelength of 0.31 μm, is presented. The device performance is evaluated by investigating both the current density-voltage characteristics and the spectral response (SR). The proposed structure is optimized in terms of the fundamental geometrical and doping parameters. During the simulations, it was found that the detector is sensitive to the UV rays in the 0.155–0.37 μm wavelength range and the spectral response can reach 0.156 A W-1 under a light intensity of 1 Wcm−2 at zero-bias voltage and room temperature. This SR peak value increases further under reverse bias conditions. The temperature effect on the detector SR and the impact of an explicit trap concentration located into the p+ and n-region are also investigated. The spectral response decreases for a temperature exceeding 420 K. At the same time, the SR reference values begin to be affected only for acceptor and donor trap densities that are much higher than the local (total) doping concentration.

Simulation of Gaussian energy broadening in gamma response of a LYSO array detector using a semi-empirical method

The energy broadening parameters for a $10 \times 10$ LYSO:Ce array were determined experimentally in an energy range of 59keV to ∼ 1300 keV for gamma rays. The obtained parameters can be used to improve the Monte Carlo simulation of the spectral behavior of the LYSO-based detectors, especially in PET imaging systems. The detector spectral responses were simulated by the MCNP4c code using the obtained parameters. The obtained results from the simulations were verified using real gamma spectra.

Performance Analysis of a Pt/n-GaN Schottky Barrier UV Detector

The electrical and optical characteristics of an n-type gallium nitride (GaN)-based Schottky barrier ultraviolet (UV) detector, where a platinum (Pt) metal layer forms the anode contact, have been evaluated by means of detailed numerical simulations considering a wide range of incident light intensities. By modeling the GaN physical properties, the detector current density–voltage characteristics and spectral responsivity for different (forward and reverse) bias voltages and temperatures are presented, assuming incident optical power ranging from 0.001 W cm−2 to 1 W cm−2. The effect of defect states in the GaN substrate is also investigated. The results show that, at room temperature and under reverse bias voltage of −300 V, the dark current density is in the limit of 2.18 × 10−19 A cm−2. On illumination by a 0.36-μm UV uniform beam with intensity of 1 W cm−2, the photocurrent significantly increased to 2.33 A cm−2 and the detector spectral responsivity reached a maximum value of 0.2 A W−1 at zero bias voltage. Deep acceptor trap states and high temperature strongly affected the spectral responsivity curve in the considered 0.2 μm to 0.4 μm UV spectral range.

Analysis of the Multichannel WDM-VLC Communication System

Visible light communication (VLC) systems can achieve a higher data rate by increasing the number of channels using wavelength division multiplexing (WDM) technology. In this paper, we investigate the maximum number of channels and possible data rate in a WDM-VLC system based on light emitting diode (LED). Channel crosstalk from the spectral overlap of LEDs is analyzed by modeling LED spectra and the formula for crosstalk is derived from VLC link, including optical filter transmittance and detector spectral response. An experimental setup with different wavelength of LEDs is used to confirm the validity of the crosstalk analysis. The number of channels and data rate are determined by the SNR, including signal power, channel crosstalk, and detector noise. The results indicate that for indoor illumination standard with on – off keying modulation and 33 nm channel spacing to achieve a BER of $10^{- 6}$ , the maximum and optimal numbers of channels are 12 and 10, respectively. Additionally, the achievable data rate is 5.1 Gb/s which is about 9.3 times than that of the single channel system.

Effect of photometric detector spectral response quality on white LED spectral mismatch correction factors.

Light-emitting-diode (LED)-based solid-state lighting has become a real option for private and public lighting after achieving high total luminous flux (TLF) and luminous efficacy levels, thus promoting the development of energy efficient use regulation to be fulfilled by LED lamps and LED luminaires. Here, we propose a photometer-quality-based fast-checking criterion. This allows photometric technicians to perform a quick evaluation of the photometric head spectral response quality effect on the LED source spectral mismatch correction factor-when determining the TLF and luminous efficacy minimum approved levels-performance parameters subject to mandatory verification by the conformity assessment procedures technically supporting the corresponding regulation. The proposed criterion applies for a wide range of photometric detector heads' qualities (2.6%≤f1'≤36.4%).

Determination of Gaussian energy broadening parameters for organic scintillators

The aim of this work is to find the energy broadening parameters for organic scintillators as gamma detectors. A combined experimental and Monte Carlo method was used to determine the energy resolution curve for a 2′′ × 2′′ BC400 plastic scintillator detector in the energy range of 20 keV to ∼ 1000 keV. The obtained parameters can be used to improve the Monte Carlo simulation of spectral behavior of the plastic scintillators. The detector spectral responses were simulated by MCNP4c code before and after applying the energy broadening parameters. The obtained results from the simulations showed a good agreement with experimental data after including the energy broadening parameters.

Analysis of channel crosstalk in muliti-spectrum visible light communication system

In visible light communication, the wavelength division mutiplexing (WDM) technology can improve system data rate by increasing the number of channels. However, because the emission spectrum of the light emitting diode (LED) has a certain width, a phenomenon of spectral overlapping will occur when the number of channels increases and channel-spacing decreases, which results in channel crosstalk although optical filters are adopted. The channel crosstalk will restrict the capacity of WDM-VLC (visible light communication) system, which has great research significance. In this paper, the channel crosstalk based on LED spectra overapping is disscussed. The LED emission spectrum is modeled by combining the physical mechanism of LED emission with real shape of LED spectrum. According to the literature, the LED shape can be fitted greatly by Gauss function, and the full-width at half-maximum E is in a range from about 4.3kBTj to 6.8kBTj when the peak wavelengths of InGaN and AlInGaN LEDs are both less than 560 nm, E values range from 2.1kBTj to 3.3kBTj when the peak wavelength of InAlGaP LED is larger than 560 nm. In order to reduce the overall system complexity we use the following values: when the peak wavelength is less than 560 nm, E = 5.5kBTj; when the peak wavelength is larger than 560 nm, E = 3.0kBTj. Then, according to the overlapping spectra and VLC channel with considering optical filter transmittance and detector spectral response, the channel crosstalk formula is derived. Some quantities are given before simulation such as the semi-angle at half illuminance of an LED is 60; all LEDs are so closely arranged together to mix light in free space that spacing between LEDs can be ignored with respect to the propagating distance; the strongest signal situation is considered. The simulation result shows that although at the same channel spacing, different channels have different crosstalks because spectra are different. And the crosstalk from one adjacent channel will not exceed -13.6 dB when channel-spacing is larger than and equal to 28 nm, which means that when OOK modulation is used and the BER achieve 10-6, the channel-spacing should not be less than 28 nm. Finally, an experiment of channel crosstalk with using two-channel WDM VLC system and LEDs with different wavelengths is conducted and the correctness of the crosstalk analysis is verified. The colors of red (635 nm), red-orange (620 nm) and amber (596 nm) LEDs are used and two of them are used each time. Two sine signals with different frequencies are launched by AWGs (Agilent 33250A) and through amplifiers and Bias-Tees, drive two LEDs. The signal analyzer (Agilent N9020A) is used to observe the signal power. The experimental results of channle crosstalk are close to theoretical results. The analysis of channel crosstalk in muliti-channel WDM-VLC system will give some guidance in increasing the number of channels for optical communication in the future.

用于探测器中红外绝对光谱响应度测量的激光源

用于探测器中红外绝对光谱响应度测量的激光源

Study of Charge Diffusion in a Silicon Detector Using an Energy Sensitive Pixel Readout Chip

A $300~\mu\hbox{m}$ thick thin p-on-n silicon sensor was connected to an energy sensitive pixel readout ASIC and exposed to a beam of highly energetic charged particles. By exploiting the spectral information and the fine segmentation of the detector, we were able to measure the evolution of the transverse profile of the charge carriers cloud in the sensor as a function of the drift distance from the point of generation. The result does not rely on model assumptions or electric field calculations. The data are also used to validate numerical simulations and to predict the detector spectral response to an X-ray fluorescence spectrum for applications in X-ray imaging.

Soft X-ray tomographic reconstruction of JET ILW plasmas with tungsten impurity and different spectral response of detectors

The Joint European Torus (JET) presently operates with the ITER-like wall (ILW) including tungsten divertor. Analyses of the soft X-ray radiation (SXR) data present an important tool for studies of transport of tungsten into JET plasmas. SXR spatial distribution can be measured by horizontal (H) and two vertical (V,T) pinhole cameras. Tomographic reconstruction of SXR emissivity from their data is challenging due to different spectral sensitivities of the cameras which can cause significant inconsistencies due to spectral properties of tungsten radiation. In this contribution an advanced correction based on evaluation of the sensitivity differences for individual lines of view of the SXR detectors is presented. The adjustments take into account atomic data of tungsten as well as the SXR intensity perturbation due to tungsten influx. First results are presented and discussed.

A comprehensive simulation study of a Liquid-Xe detector for contraband detection

Recently, a new detector concept, for combined imaging and spectroscopy of fast-neutrons and gamma rays was presented. It encompasses a liquid-xenon (LXe) converter-scintillator coupled to a UV-sensitive gaseous Thick Gas Electron Multiplier (THGEM)-based imaging photomultiplier (GPM).In this work we present and discuss the results of a systematic computer-simulation study aiming at optimizing the type and performance of LXe converters. We have evaluated the detector spectral response, detection efficiency and spatial resolution for gamma-rays and neutrons in the energy range of 2–15 MeV for 50 mm thick converters consisting of plain LXe volume and LXe-filled capillaries, of Teflon, Polyethylene or hydrogen-containing Teflon (Tefzel).Neutron detection efficiencies for plain LXe, Teflon-capillaries and Tefzel-capillaries converters were about 20% over the entire energy range. In polyethylene capillaries converters the neutron detection efficiency was about 10% at 2 MeV and increased up to about 20% at 14 MeV . Detection efficiencies of gammas in Teflon, Tefzel and polyethylene converters were ∼ 35%. The plain-LXe converter provided the highest gamma-ray detection efficiency, of 0∼ 4–50% in the 2–15 MeV energy range.Optimization of LXe-filled Tefzel capillary dimensions resulted in spatial resolution of ∼ 1.5 mm (FWHM) for neutrons and up to 3.5 mm (FWHM) for gamma-rays.Simulations of radiographic images of various materials using two discrete energy gamma-rays (4.4 MeV and 15.1 MeV) and neutrons in a broad energy range (2–10 MeV) were performed in order to evaluate the potential of elemental discrimination.

ASTRO-H CdTe detectors proton irradiation at PIF

Asbstract The French Atomic Energy Commission (CEA), with the support of the European Space Agency (ESA), is partner of the Soft Gamma-Ray Detector (SGD) and the Hard X-ray Imager (HXI) onboard the 6th Japanese X-ray scientific satellite ASTRO-H (JAXA) initiated by the Institute of Space and Astronautical Science (ISAS). Both scientific instruments, one hosting a series of Compton Gamma Cameras and the other being a focal plane of a grazing incidence mirror telescope in the hard X-ray domain, are equipped with Cadmium Telluride based detectors. ASTRO-H will be operated in a Low Earth Orbit with a 31° inclination at ~550 km altitude, thus passing daily through the South Atlantic Anomaly radiation belt, a specially harsh environment where the detectors are suffering the effect of the interaction with trapped high energy protons. As CdTe detector performance might be affected by the irradiation, we investigate the effect of the accumulated proton fluence on their spectral response. To do so, we have characterized and irradiated representative samples of SGD and HXI detector under different conditions. The detectors in question, from ACRORAD, are single-pixels having a size of 2 mm by 2 mm and 750 µm thick. The Schottky contact is either made of an Indium or Aluminum for SGD and HXI respectively. We ran the irradiation test campaign at the Proton Irradiation Facility (PIF) at PSI, and ESA approved equipment to evaluate the radiation hardness of flight hardware. We simulated the proton flux expected on the sensors over the entire mission, and secondary neutrons flux due to primary proton interactions into the surrounding BGO active shielding. We eventually characterized the detector response evolution, emphasizing each detector spectral response as well as its stability by studying the so-called Polarization effect. The latter is provoking a spectral response degradation against time as a charge accumulation process occurs in Schottky type CdTe sensors. In this paper, we report on the test campaigns at PIF and will show up our experimental setup. We will pursue describing the irradiation conditions associated with our GEANT 4 predictions and finally, we report the main results of our campaigns concluding that the proton effect does not severely affect the CdTe response neither the detector stability while the secondary neutrons might be more active to reduce the performance on the long run.