Search

Very precise on-ground characterization and calibration of TESS CCD detectors will significantly assist in the analysis of the science data from the mission. An accurate optical test bench with very high photometric stability has been developed to perform precise measurements of the absolute quantum efficiency. The setup consists of a vacuum dewar with a single MIT Lincoln Lab CCID-80 device mounted on a cold plate with the calibrated reference photodiode mounted next to the CCD. A very stable laser-driven light source is integrated with a closed-loop intensity stabilization unit to control variations of the light source down to a few parts-per-million when averaged over 60 s. Light from the stabilization unit enters a 20 inch integrating sphere. The output light from the sphere produces near-uniform illumination on the cold CCD and on the calibrated reference photodiode inside the dewar. The ratio of the CCD and photodiode signals provides the absolute quantum efficiency measurement. The design, key features, error analysis, and results from the test campaign are presented., United States. National Aeronautics and Space Administration (contract number NNG14FC03C)

Note: Accepted for Publication as a Letter to the Editor in PUBLICATION OF THE ASTRONOMICAL SOCIETY OF JAPAN, 1994, February 11

The Regolith x-ray Imaging Spectrometer (REXIS) is a coded-aperture soft x-ray imaging instrument on the OSIRIS-REx spacecraft to be launched in 2016. The spacecraft will fly to and orbit the near-Earth asteroid Bennu, while REXIS maps the elemental distribution on the asteroid using x-ray fluorescence. The detector consists of a 2×2 array of backilluminated 1k×1k frame transfer CCDs with a flight heritage to Suzaku and Chandra. The back surface has a thin p[superscript +]-doped layer deposited by molecular-beam epitaxy (MBE) for maximum quantum efficiency and energy resolution at low x-ray energies. The CCDs also feature an integrated optical-blocking filter (OBF) to suppress visible and near-infrared light. The OBF is an aluminum film deposited directly on the CCD back surface and is mechanically more robust and less absorptive of x-rays than the conventional free-standing aluminum-coated polymer films. The CCDs have charge transfer inefficiencies of less than 10[superscript -6], and dark current of 1e-/pixel/second at the REXIS operating temperature of –60 °C. The resulting spectral resolution is 115 eV at 2 KeV. The extinction ratio of the filter is ~10[superscript 12] at 625 nm., United States. National Aeronautics and Space Administration. Strategic Astrophysics Technology Program (Grant NNX12AF22G), United States. National Aeronautics and Space Administration (Contract NNG12FD70C), United States. National Aeronautics and Space Administration (IPR NNG12FC01I), United States. National Aeronautics and Space Administration. Strategic Astrophysics Technology Program (IPR NNH12AU04I), United States. Air Force (Contract FA8721-05-C-0002)

The OSIRIS-REx Mission was selected under the NASA New Frontiers program and is scheduled for launch in September of 2016 for a rendezvous with, and collection of a sample from the surface of asteroid Bennu in 2019. 101955 Bennu (previously 1999 RQ36) is an Apollo (near-Earth) asteroid originally discovered by the LINEAR project in 1999 which has since been classified as a potentially hazardous near-Earth object. The REgolith X-Ray Imaging Spectrometer (REXIS) was proposed jointly by MIT and Harvard and was subsequently accepted as a student led instrument for the determination of the elemental composition of the asteroid's surface as well as the surface distribution of select elements through solar induced X-ray fluorescence. REXIS consists of a detector plane that contains 4 X-ray CCDs integrated into a wide field coded aperture telescope with a focal length of 20 em for the detection of regions with enhanced abundance in key elements at 50 m scales. Elemental surface distributions of approximately 50-200 m scales can be detected using the instrument as a simple collimator. An overview of the observation strategy of the REXIS instrument and expected performance are presented here., United States. National Aeronautics and Space Administration (Grant NNX12AG65G), United States. National Aeronautics and Space Administration (Grant NNG12FD70C)

The Micro-X High Resolution Microcalorimeter X-ray Imaging Rocket is a sounding rocket experiment that will combine a transition-edge-sensor X-ray-microcalorimeter array with a conical imaging mirror to obtain high- spectral-resolution images of extended X-ray sources. The target for Micro-X’s first flight (slated for January 2013) is the Puppis A supernova remnant. The Micro-X observation of the bright eastern knot of Puppis A will obtain a line-dominated spectrum with up to 27,000 counts collected in 300 seconds at 2 eV resolution across the 0.3-2.5 keV band. Micro-X will determine the thermodynamic and ionization state of the plasma, search for line shifts and broadening associated with dynamical processes, and seek evidence of ejecta enhancement. We describe the progress made in developing this payload, including the detector, cryogenics, and electronics assemblies., United States. National Aeronautics and Space Administration (NASA award NNX10AE25G), Kathy and Curt Marble Cancer Research Fund

We have developed a hybrid Active Pixel Sensor for detecting low energy X-rays. The sensor consists of a silicon diode detector array built on a high resistivity wafer and an SOI CMOS readout circuit, connected together by means of unique 3D integration technology developed at MIT Lincoln Laboratory. In this paper we will describe measurements of sense node capacitance and device depletion depth along with corresponding simulations aimed to optimize device performance. We also describe race condition in the column decoder and identify ways to eliminate it in order to reduce fixed pattern noise., United States. National Aeronautics and Space Administration (NASA) (Grant NNG06WC08G)

MIT Lincoln Laboratories and MIT Kavli Institute for Astrophysics and Space Research have developed an active pixel sensor for use as a photon counting device for imaging spectroscopy in the soft X-ray band. A silicon-on-insulator (SOI) readout circuit was integrated with a high-resistivity silicon diode detector array using a per-pixel 3D integration technique developed at Lincoln Laboratory. We have tested these devices at 5.9 keV and 1.5 keV. Here we examine the interpixel cross-talk measured with 5.9 keV X-rays., United States. National Aeronautics and Space Administration (NASA) (Grant NNG06WC08G)

We have developed a hybrid Active Pixel Sensor for detecting low energy X-rays. The sensor consists of a silicon diode detector array built on a high resistivity wafer and an SOI CMOS readout circuit, connected together by means of unique 3D integration technology developed at MIT Lincoln Laboratory. In this paper we will describe measurements of sense node capacitance and device depletion depth along with corresponding simulations aimed to optimize device performance. We also describe race condition in the column decoder and identify ways to eliminate it in order to reduce fixed pattern noise., United States. National Aeronautics and Space Administration (NASA) (Grant NNG06WC08G)

We have developed a back-illuminated active pixel sensor (APS) which includes an SOI readout circuit and a silicon diode detector array implemented in a separate high-resistivity wafer. Both are connected together using a per-pixel 3-D integration technique developed at Lincoln Laboratory. The device was fabricated as part of a program to develop a photon-counting APS for imaging spectroscopy in the soft X-ray (0.3-10-keV) spectral band. Here, we report single-pixel X-ray response with spectral resolution of 181-eV full-width at half-maximum at 5.9 keV. The X-ray data allow us to characterize the responsivity and input-referred noise properties of the device. We measured interpixel crosstalk and found large left-right asymmetry explained by coupling of the sense node to the source follower output. We have measured noise parameters of the SOI transistors and determined factors which limit the device performance., United States. National Aeronautics and Space Administration (Grant NNG06WC08G)

The Micro-X High Resolution Microcalorimeter X-ray Imaging Rocket is sounding rocket experiment that will combine a transition-edge-sensor X-ray-microcalorimeter array with a conical imaging mirror to obtain high-spectral-resolution images of extended and point X-ray sources. Our first target is the Puppis A supernova remnant, which will be observed in January 2011. The Micro-X observation of the bright eastern knot of Puppis A will obtain a line-dominated spectrum with up to 90,000 counts collected in 300 seconds at 2 eV resolution across the 0.3-2.5 keV band. Micro-X will utilize plasma diagnostics to determine the thermodynamic and ionization state of the plasma, to search for line shifts and broadening associated with dynamical processes, and seek evidence of ejecta enhancement. We describe the progress made in developing this payload, including the detector, cryogenics, and electronics assemblies. A detailed modeling effort has been undertaken to design a rocket-bourne adiabatic demagnetization refrigerator with sufficient magnetic shielding to allow stable operation of transition edge sensors, and the associated rocket electronics have been prototyped and tested.

The Micro-X High Resolution Microcalorimeter X-ray Imaging Rocket is sounding rocket experiment that will combine a transition-edge-sensor X-ray-microcalorimeter array with a conical imaging mirror to obtain high-spectral-resolution images of extended and point X-ray sources. Our first target is the Puppis A supernova remnant, which will be observed in January 2011. The Micro-X observation of the bright eastern knot of Puppis A will obtain a line-dominated spectrum with up to 90,000 counts collected in 300 seconds at 2 eV resolution across the 0.3-2.5 keV band. Micro-X will utilize plasma diagnostics to determine the thermodynamic and ionization state of the plasma, to search for line shifts and broadening associated with dynamical processes, and seek evidence of ejecta enhancement. We describe the progress made in developing this payload, including the detector, cryogenics, and electronics assemblies. A detailed modeling effort has been undertaken to design a rocket-bourne adiabatic demagnetization refrigerator with sufficient magnetic shielding to allow stable operation of transition edge sensors, and the associated rocket electronics have been prototyped and tested.

We have developed a back-illuminated active pixel sensor (APS) which includes an SOI readout circuit and a silicon diode detector array implemented in a separate high-resistivity wafer. Both are connected together using a per-pixel 3-D integration technique developed at Lincoln Laboratory. The device was fabricated as part of a program to develop a photon-counting APS for imaging spectroscopy in the soft X-ray (0.3-10-keV) spectral band. Here, we report single-pixel X-ray response with spectral resolution of 181-eV full-width at half-maximum at 5.9 keV. The X-ray data allow us to characterize the responsivity and input-referred noise properties of the device. We measured interpixel crosstalk and found large left-right asymmetry explained by coupling of the sense node to the source follower output. We have measured noise parameters of the SOI transistors and determined factors which limit the device performance., United States. National Aeronautics and Space Administration (Grant NNG06WC08G)

The X-ray Imaging Spectrometer (XIS) on board the Suzaku satellite is an X-ray CCD camera system that has features of a low background, high quantum efficiency, and good energy resolution in the 0.2 - 12 keV band. Because of the radiation damage, however, the energy resolution of the XIS has been degraded since Suzaku was launched (July 2005). One of the major advantages of the XIS over the other X-ray CCDs in orbit is the provision of a precision charge injection (CI) capability. In order to improve the energy resolution, the precise measurement of charge transfer inefficiency (CTI) is essential. For this purpose, we applied the checker-flag CI, and we were able to measure the CTI of each CCD column. Furthermore, we were able to obtain the pulse height dependency of the CTI. Our precise CTI correction using these results improved the energy resolution from 193 eV to 173 eV in FWHM at 5.9 keV in July 2006 (one year after the launch). The energy resolution can be improved also by reducing the CTI. For this purpose, we applied the spaced-row charge injection (SCI); periodically injected artificial charges work as if they compensate radiation-induced traps and prevent electrons produced by X-rays from being captured by the charge traps. Using this method, the energy resolution improved from 210 eV to 150 eV at 5.9 keV in September 2006, which is close to the resolution just after the launch (145 eV). We report the current in-orbit calibration status of the XIS data using these two techniques. We present the time history of the gain and energy resolution determined from onboard calibration sources ([subscript 55]Fe) and observed calibration objects like E0102-72.

Since the launch of the Suzaku X-ray astronomy satellite into low- earth orbit in July, 2005, the performance of the CCD detectors in the X-ray Imaging Spectrometer (XIS) detectors have slowly degraded, as expected, due to accumulating radiation damage. We compare the evolution of front- and back-illuminated XIS CCDs with one another and with that of very similar detectors installed in the ACIS instrument aboard the Chandra X-ray Observatory, which is in a much higher orbit than Suzaku. We attempt to identify effects of the differing radiation environments as well as those arising from structural differences between the two types of detector., Japan Aerospace Exploration Agency, Institute of Space and Astronautical Science, National Aeronautics and Space Administration (contracts NAS8-37716 and NNG-05GM92G)