The filter and calibration wheel for the ATHENA wide field imager

Rataj, M.; Polak, Szymon; Palgan, Tomasz; Kamisiński, Tadeusz; Pilch, Adam; Eder, Josef; Meidinger, Norbert; Plattner, Markus; Barbera, Marco; Parodi, Giancarlo; D'Anca, Fabio

doi:10.1117/12.2235411

Cited by 7 publications

(4 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The use of an additional OBF mounted on a filter wheel (FW) is thus necessary. In addition, the FW will provide an open aperture, a closed position and calibration sources [18]. Figure 2 shows a schematic drawing of the WFI showing the position of the FW OBF in the context of the main instrument subsystems.…”

Section: Current Investigated Designmentioning

confidence: 99%

ATHENA WFI optical blocking filters development status toward the end of the instrument phase-A

Barbera

Cicero

Sciortino

et al. 2018

Space Telescopes and Instrumentation 2018: Ultraviolet to Gamma Ray

Self Cite

View full text Add to dashboard Cite

The Wide Field Imager (WFI) is one of the two instruments of the ATHENA astrophysics space mission approved by ESA as the second large mission in the Cosmic Vision 2015-2025 Science Programme. The WFI, based on a large array of depleted field effect transistors (DEPFET), will provide imaging in the 0.2-15 keV band over a 40'x40' field of view, simultaneously with spectrally and time resolved photon counting.The WFI detector is also sensitive to UV/Vis photons, with an electron-hole pair production efficiency in the UV/VIS larger than that for X-ray photons. Optically generated photo-electrons may degrade the spectral resolution as well as change the energy scale by introducing a signal offset. For this reason, the use of X-ray transparent optical blocking filters (OBFs) are needed to allow the observation of X-ray sources that present a UV/Vis bright counterpart.The OBFs design is challenging since one of the two required filters is quite large (~ 160 mm  160 mm), very thin (< 200 nm), and shall survive the mechanical load during the launch.In this paper, we review the main results of modeling and characterization tests of OBF partially representative samples, performed during the phase A study, to identify the suitable materials, optimize the design, prove that the filters can be launched in atmospheric pressure, and thus demonstrate that the chosen technology can reach the proper technical readiness before mission adoption.

show abstract

Section: Current Investigated Designmentioning

confidence: 99%

ATHENA WFI optical blocking filters development status toward the end of the instrument phase-A

Barbera

Cicero

Sciortino

et al. 2018

Space Telescopes and Instrumentation 2018: Ultraviolet to Gamma Ray

Self Cite

View full text Add to dashboard Cite

show abstract

“…Further details about the filters and the filter wheel are given in ref. [6] and [7]. The camera head is mounted directly to the filter wheel (see Figure 2).…”

Section: Wfi Overview 21 Conceptual Designmentioning

confidence: 99%

The wide field imager instrument for Athena

et al. 2014

View full text Add to dashboard Cite

The "Hot and Energetic Universe" has been selected as the science theme for ESA's L2 mission, scheduled for launch in 2028. The proposed Athena X-ray observatory provides the necessary capabilities to achieve the ambitious goals of the science theme. The X-ray mirrors are based on silicon pore optics technology and will have a 12 m focal length. Two complementary camera systems are foreseen which can be moved in and out of the focal plane by an interchange mechanism. These instruments are the actively shielded micro-calorimeter spectrometer X-IFU and the Wide Field Imager (WFI).The WFI will combine an unprecedented survey power through its large field of view of 40 arcmin with a high countrate capability (approx. 1 Crab). It permits a state-of-the-art energy resolution in the energy band of 0.1 keV to 15 keV during the entire mission lifetime (e.g. FWHM ≤ 150 eV at 6 keV). This performance is accomplished by a set of DEPFET active pixel sensor matrices with a pixel size matching the angular resolution of 5 arcsec (on-axis) of the mirror system. Each DEPFET pixel is a combined detector-amplifier structure with a MOSFET integrated onto a fully depleted 450 micron thick silicon bulk. The signal electrons generated by an X-ray photon are collected in a so-called internal gate below the transistor channel. The resulting change of the conductivity of the transistor channel is proportional to the number of electrons and thus a measure for the photon energy. DEPFETs have already been developed for the "Mercury Imaging X-ray Spectrometer" on-board of ESA's BepiColombo mission. For Athena we develop enhanced sensors with integrated electronic shutter and an additional analog storage area in each pixel. These features improve the peak-to-background ratio of the spectra and minimize dead time. The sensor will be read out with a new, fast, low-noise multi-channel analog signal processor with integrated sequencer and serial analog output. The architecture of sensor and readout ASIC allows readout in full frame mode and window mode as well by addressing selectively arbitrary sub-areas of the sensor allowing time resolution in the order of 10 µs. The further detector electronics has mainly the following tasks: digitization, pre-processing and telemetry of event data as well as supply and control of the detector system. Although the sensor will already be equipped with an on-chip light blocking filter, a filter wheel is necessary to provide an additional external filter, an on-board calibration source, an open position for outgassing, and a closed position for protection of the sensor. The sensor concept provides high quantum efficiency over the entire energy band and we intend to keep the instrumental background as low as possible by designing a graded Zshield around the sensor.All these properties make the WFI a very powerful survey instrument, significantly surpassing currently existing observatories and in addition allow high-time resolution of the brightest X-ray sources with low pile-up and high efficiency. This manuscript ...

show abstract

“…The results will give the input parameters for the filter acoustic simulation, and help to decide if the launch of the module in atmospheric conditions is possible. As it was shown in previous papers (Barbera et al, 2015;Rataj et al, 2016), the filterwheel assembly can modify the sound pressure level in the filter position. It is especially dangerous for low frequencies, where the signal can be locally amplified by the assembly resonances, what results in large SPLs.…”

Section: Introductionmentioning

confidence: 96%

Acoustic Simulation’s Verification of WFI ATHENA Filterwheel Assembly

Pilch

Kamisiński

Rataj

et al. 2017

Archives of Acoustics

View full text Add to dashboard Cite

Ariane 5 rocket produces very high sound pressure levels during launch, what can influence structures located in the fairing. To reduce risk of damage, launch in vacuum conditions is preferred for noise sensitive instruments. In Wide Filed Imager (WFI) project, the main part of the filterwheel assembly is an extremely thin (∼240 nm) filter of large area (170 × 170 mm), very sensitive to noise and vibrations.The aim of this study was to verify numerical calculations results in anechoic measurements. The authors also checked the influence of WFI geometry and sound absorbing material position on sound pressure level (SPL) affecting the filter mounted inside the assembly. Finite element method (FEM) simulations were conducted in order to obtain noise levels in filter position during Ariane 5 rocket launch. The results will be used in designing of WFI filterwheel assembly and endurance of the filter during launch verification.

show abstract

The filter and calibration wheel for the ATHENA wide field imager

Cited by 7 publications

References 1 publication

ATHENA WFI optical blocking filters development status toward the end of the instrument phase-A

ATHENA WFI optical blocking filters development status toward the end of the instrument phase-A

The wide field imager instrument for Athena

Acoustic Simulation’s Verification of WFI ATHENA Filterwheel Assembly

Contact Info

Product

Resources

About