The paper presents a method for determining the pixel response using Geant4 package. The response is calculated for cadmium telluride sensor of Caliste-SO detector. Caliste-SO will be used in STIX instrument on board Solar Orbiter, which is M-class mission of the ESA’s program Cosmic Vision 2015-2025. Solar Orbiter is to be launched in October 2018. STIX instrument will provide imaging spectroscopy of solar hard X-ray emissions (4 – 150 keV) using a Fourier-imaging technique. Response of pixels in pixelized Caliste-SO detector vary between each other due to different sizes and locations. This can influence the scientific data obtained from STIX. Additionally, in the simulation we considered detector effects, like: hole tailing, damage layer, Fano and electronic noise.
The Soft X-ray Solar polarimeter-spectrometer (SOLPEX) experiment is planned to be placed in Roscosmos’ Multipurpose Laboratory Module “NAUKA” on International Space Station (ISS) in 2019. The experiment is design to detect polarization and X-ray spectra of solar flares. Due to very high, few percent, linear polarization detection limit, accurate background estimation and modeling is crucial.
Calculating the background photoelectric effect, Compton scattering and Bremsstrahlung were taken into account. Luminescence background from particles produced in solar flares was simulated using Geant4. Additionally, theoretical spectra was modeled in order to simulate full SOLPEX detector response for M5 and X1 solar flare classes.
Detection of polarization and spectra measurement of X-ray solar flare emission are indispensable in improving our understanding of the processes releasing energy of these most energetic phenomena in the solar system. We shall present some details of the construction of SolpeX – an innovative Bragg soft X-ray flare polarimeter and spectrometer. The instrument is a part of KORTES – Russian instrument complex to be mounted aboard the science module to be attached to the International Space Station (2017/2018).
The SolpeX will be composed of three individual measuring units: the soft X-ray polarimeter with 1-2% linear polarization detection threshold, a fast-rotating flat crystal X-ray spectrometer with a very high time resolution (0.1 s) and a simple pinhole soft X-ray imager-spectrometer with a moderate spatial (~20 arcsec), spectral (0.5 keV) and high time resolution (0.1 s). Having a fast rotating unit to be served with power, telemetry and “intelligence” poses a challenge for the designer. Some of the solutions to this will be provided and described.
The paper presents a two methods for simulation of signal induction in the detector. First method base on carriers tracks calculation while second method include simplification of accelerating calculations. Calculation has been performed for Caliste-SO detector, which is cadmium telluride X-ray detector. This detector will be used in the Solar Orbiter/STIX instrument. Solar Orbiter is M-class mission of the ESA's programme Cosmic Vision 2015-2025, which is conducted in collaboration with NASA. It will be launched in October 2018. STIX (Spectrometer/Telescope for Imaging X-Rays) is X-ray telescope and spectrometer and will observe solar X-ray emission from 4 to 150 keV using Fourier-imaging technique. Deep space condition can influence significantly the detector parameters. Tools for detectors behaviour analysis are needed to understand how this harsh radiation environment can influence detector quantum efficiency.
The paper presents a method for determining the Detector Response Matrix (DRM) using Monte Carlo simulations.
For this purpose Geant4 package was used which enables simulations of the interaction of particles with matter.
The DRM has been calculated for cadmium telluride sensor of Caliste-SO detector, which will be used in the Solar
Orbiter/STIX instrument. Solar Orbiter is the M-class mission of the new ESA’s program Cosmic Vision 2015-2025.
It is to be launched in July 2017. STIX will provide imaging spectroscopy of solar hard X-ray emissions from 4 keV
to 150 keV using a Fourier-imaging technique. Long operation of detectors under space condition raises a need
for development of dedicated tools for analysis of behaviour of the detectors in changing/harsh radiation environment
and its impact on detector quantum efficiency due to aging effects. Obtained results exhibit a high usefulness of Geant4
package in this kind of analysis.
Solar Orbiter mission of European Space Agency, scheduled for launch in 2017, is designed to explore the Sun and the
inner heliosphere. Its close, never achieved before by any other spacecraft, approach to the Sun as well as ten remote-sensing
and in-situ on board instruments will allow obtaining unique solar science data. The Spectrometer Telescope for
Imaging X-rays (STIX) is one of them. Its measurements of solar thermal and non-thermal hard X-ray emissions from
~4 to 150 keV will play an important role to achieve mission's major science goals. The Spacecraft Instrument Interface
Simulator (SIIS) is specified as a part of Electrical Ground Support Equipment with the aim to provide a tool for power
interface and telemetry/telecommand electrical and data protocol validation during the delivery phase of STIX
instrument for spacecraft integration. It is designed to be used during the instrument development and test phases of onboard
algorithms, too. Brief overview of SIIS use and performance for these purposes is given in this work.
We present an innovative soft X-ray polarimeter and spectrometer SOLPEX, the instrument to be mounted aboard the International Space Station (ISS) in 2015/2016. The SOLPEX will be composed of three individual measuring units: the soft X-ray polarimeter with 1-2% linear polarization detection limit, a fast-rotating drum X-ray spectrometer with very high time resolution (0.1s) and a simple pin-hole soft X-ray imager-spectrometer with moderate spatial (~20arcsec), spectral (0.5 keV) and high time resolution (0.1s). This set of instruments will provide unique opportunity to complement the efforts to reliably measure the X-ray polarization and contribute towards understanding the physics of solar flares. The standard flare model states that electrons are being accelerated in specific regions of the corona at or near magnetic reconnection site and then propagate along reconnected magnetic field lines toward the atmospheric denser layers. There, they are decelerated and lose their energy mainly through the bremsstrahlung process. Deposited energy is readily converted to directed evaporation of the plasma to be detected through the Doppler-shifted emission lines in extreme ultraviolet and soft X-ray spectral ranges Due to highly anisotropic character of impulsive phase electron beams, resulting emission is expected to be polarized. Both these processes: bremsstrahlung emission of supposedly polarized X-ray flux and accompanying plasma evaporation velocities are to be simultaneously observed by the proposed SOLPEX instruments.
The Spectrometer Telescope for Imaging X-rays (STIX) is one of 10 instruments on-board Solar Orbiter mission of the European Space Agency (ESA) scheduled to be launched in 2017. STIX is aimed to provide imaging spectroscopy of solar thermal and non-thermal hard X-ray emissions from 4 keV to 150 keV using a Fourier-imaging technique. The instrument employs a set of tungsten grids in front of 32 pixelized CdTe detectors. These detectors are source of data collected and analyzed in real time by Instrument Data Processing Unit (IDPU). In order to support development and implementation of on-board algorithms a dedicated detector hardware simulator is designed and manufactured as a part of Electrical Ground Support Equipment (EGSE) for STIX instrument. Complementary to the hardware simulator is data analysis software which is used to generate input data and to analyze output data. The simulator will allow sending strictly defined data from all detectors’ pixels at the input of the IDPU for further analysis of instrument response. Particular emphasis is given here to the simulator hardware design.