IXPE (Imaging X-ray Polarimetry Explorer) is the next Nasa Small Explorer mission foreseen for the lunch in 2021. It is a partnership with the Italian Space Agency (ASI). IXPE is devoted to X-ray polarimetry in the 2-8 keV energy band. The IXPE telescope comprises three grazing incidence mirror modules coupled to three detector units hosting each one a Gas Pixel Detector (GPD) polarimeter. The GPD exploits the photoelectric effect to measure the linear polarization of the X-ray emission from astrophysical sources. A wide and accurate on ground calibration was carried out on the IXPE detector units at INAF-IAPS in Italy. A dedicated facility was set-up to calibrate the detector units with polarized and unpolarised X-rays at different energies before Instrument integration.
IXPE, the Imaging X-ray Polarimetry Explorer, is a NASA SMEX mission with an important contribution of ASI that will be launched with a Falcon 9 in 2021 and will reopen the window of X-ray polarimetry after more than 40 years. The payload features three identical telescopes each one hosting one light-weight X-ray mirror fabricated by MSFC and one detector unit with its in-orbit calibration system and the Gas Pixel Detector sensitive to imaging X-ray polarization fabricated by INAF/IAPS, INFN and OHB Italy. The focal length after boom deployment from ATK-Orbital is 4 m, while the spacecraft is being fabricated by Ball Aerospace. The sensitivity will be better than 5.5% in 300 ks for a 1E-11 erg/s/cm2 (half mCrab) in the energy band of 2-8 keV allowing for sensitive polarimetry of extended and point-like X-ray sources. The focal plane instrument is completed, calibrated and it is going to be delivered at MSFC. We will present the status of the mission at about one year from the launch.
The Imaging X-Ray Polarimetry Explorer (IXPE) is the next NASA small explorer mission, due to be launched on May 2021. It will perform polarization measures of soft X-ray photons (∼ 2 − 8keV), together with imaging, spectroscopy, and timing. The core of the detector units is the Gas Pixel Detector (GPD) with dedicated back-end electronics (BEE). We designed the latter with a radiation-tolerant FPGA for data acquisition and processing, event sequencing, and on-line data compression. Two custom digital serial interfaces implement the communication of the units with a central on-board computer: Command and Control Interface and Science Data Interface. This BEE exploits the auto-trigger capability of the GPD and can process its output of 300 photons per second with 30% of system dead time. We designed comprehensive test-equipment to emulate the on-board computer. It is based on a commercial FPGA on a VME-board together with dedicated software for control and data collection
The Imaging X-ray Polarimetry Explorer (IXPE) will add polarization to the properties (time, energy, and position) observed in x-ray astronomy. A NASA Astrophysics Small Explorer (SMEX) in partnership with the Italian Space Agency (ASI), IXPE will measure the 2–8-keV polarization of a few dozen sources during the first 2 years following its 2021 launch. The IXPE Observatory includes three identical x-ray telescopes, each comprising a 4-m-focal-length (grazingincidence) mirror module assembly (MMA) and a polarization-sensitive (imaging) detector unit (DU), separated by a deployable optical bench. The Observatory’s Spacecraft provides typical subsystems (mechanical, structural, thermal, power, electrical, telecommunications, etc.), an attitude determination and control subsystem for 3-axis stabilized pointing, and a command and data handling subsystem communicating with the science instrument and the Spacecraft subsystems.
The Imaging X-ray Polarimetry Explorer (IXPE) will expand the information space for study of cosmic sources, by adding polarization to the properties (time, energy, and position) observed in x-ray astronomy. Selected in 2017 January as a NASA Astrophysics Small Explorer (SMEX) mission, IXPE will be launched into an equatorial orbit in 2021. The IXPE observatory includes three identical x-ray telescopes, each comprising a 4-m-focal-length (grazing-incidence) mirror module assembly (MMA) and a polarization-sensitive (imaging) detector unit (DU). The optical bench separating the MMAs from the DUs is a deployable boom with a tip/tilt/rotation stage for DU-to-MMA (gang) alignment, similar to the configuration used for the NuSTAR observatory. The IXPE mission will provide scientifically meaningful measurements of the x-ray polarization of a few dozen sources in the 2-8 keV band, over the first two years of the mission. For several bright, extended x-ray sources (pulsar wind nebulae, supernova remnants, and an active-galaxy jet), IXPE observations will produce polarization maps indicating the magnetic structure of the synchrotron emitting regions. For many bright pulsating x-ray sources (isolated pulsars, accreting x-ray pulsars, and magnetars), IXPE observations will produce phase-resolved profiles of the polarization degree and position angle.
The Imaging X-ray Polarimetry Explorer is the next of the NASA’s Small Explorer Missions (SMEX) and it will expand the observation space by simultaneously adding polarization measurements to to energy, time and location. IXPE is comprised of three X-ray telescopes with three X-ray Gas Pixel Detectors (GPD) mounted on the focal plane. The GPD, developed by the IXPE Italian partner (INFN in Pisa together with INAF/IAPS in Rome) is based upon proportional counters with highly pixelated readouts provided by a low noise (∼50 e −) CMOS-based ASIC. These detectors operate in a 2-8 keV energy range and it is based on photoelectric effect. Its amplification stage consists on Gas Electron Multiplier (GEM) which allows the detector to make single photoelectron track images. The ASIC has the unique capability of self triggering with automatic ROI selection which allows to have a highly pixelated sensitive area (∼105k pixels, 50 μm pitch), affecting positively the time resolution. These characteristics make the GPD specially suited for astrophysics measurements applications. In this work I will report on the status of the polarimeter and its readout and control electronics.