G. R. Meehan

AXAF High-Resolution Camera (HRC): calibration and recalibration at XRCF and beyond

The high resolution camera (HRC) is a microchannel plate based imaging detector for the Advanced X-Ray Astrophysics Facility (AXAF) that will be placed in a high earth orbit scheduled for launch in August, 1998. An end-to-end calibration of the HRC and the AXAF high resolution mirror assembly (HRMA) was carried out at the Marshall Space Flight Centers X-Ray Calibration Facility (XRCF). This activity was followed by several modifications to the HRC to improve its performance, and a series of flat field calibrations. In this paper, and the following companion papers, we discuss the calibration plans, sequences, and results of these tests. At the time of this conference, the HRC has been fully flight qualified and is being integrated into the science instrument module (SIM) in preparation for integration into the AXAF spacecraft.

In-flight performance of the Chandra high-resolution camera

The High Resolution Camera (HRC) is one of the two focal plane instruments on NASAs Chandra X-ray Observatory which was successfully launched July 23, 1999. The Chandra Observatory will perform high resolution spectroscopy and imaging in the X-ray band of 0.1 to 10 keV. The HRC instrument consists of two detectors, the HRC-I for imaging and the HRC-S for spectroscopy. In this paper we present an overview of the in-flight performance of the High Resolution Camera and discuss some of the initial scientific results.

In-flight Performance and Calibration of the Chandra High Resolution Camera Imager (HRC-I)

In this paper we present and compare flight results with the latest results of the ground calibration for the HRC-I detector. In particular we will compare ground and in flight data on detector background, effective area, quantum efficiency and point spread response function.

Performance and calibration of the AXAF High-Resolution Camera II: the spectroscopic detector

The high resolution camera (HRC) is one of two focal plane detector systems that will be flown on the Advanced X-ray Astrophysics Facility (AXAF). The HRC consists of two microchannel plate (MCP) detectors: one to provide large area, high position resolution imaging and timing (HRC-I), and a second (HRC-S) to provide a readout for the AXAF low energy transmission gratings. Each detector is composed of a chevron pair of CsI coated MCPs with a crossed grid charge detector and an Al/polyimide UV/ion shield. In this paper, we describe the operation, performance and calibration of the spectroscopic detector. In particular, we discuss the absolute quantum efficiency calibration, the point spread function of the instrument combined with the AXAF telescope, the count rate linearity, the spatial linearity, and the internal background of the instrument. Data taken in the laboratory and at the x-ray Calibration Facility at Marshall Space Flight Center are presented.

In-flight performance and calibration of the Chandra high-resolution camera spectroscopic readout (HRC-S)

The High Resolution Camera (HRC) is one of two focal plane instruments on the NASA Chandra X-ray Observatory which was successfully launched on July 23, 1999. The Chandra X-ray Observatory was designed to perform high resolution spectroscopy and imaging in the X-ray band of 0.07 to 10 keV. The HRC instrument consists of two detectors, HRC-I for imaging and HRC-S for spectroscopy. Each HRC detector consists of a thin aluminized polyimide blocking filter, a chevron pair of microchannel plates and a crossed grid charge readout. The HRC-I is an approximately 100 X 100 mm detector optimized for high resolution imaging and timing, the HRC-S is an approximately 20 X 300 detector optimized to function as the readout for the Low Energy Transmission Grating. In this paper we discuss the in-flight performance of the HRC-S, and present preliminary analysis of flight calibration data and compare it with the results of the ground calibration and pre-flight predictions. In particular we will compare ground data and in-flight data on detector background, quantum efficiency, spatial resolution, pulse height resolution, and point spread response function.

Rockwell CMOS hybrid imager as a soft x-ray imaging spectrometer

We present preliminary results on the operation of a Rockwell CMOS Hybrid imager as a soft X-ray imaging spectrometer. The CMOS Hybrid technology provides several significant advantages over conventional CCDs for high-energy astrophysics applications, and may be a viable alternative for future missions. The Rockwell Hybrid Visible Silicon (HyViSITM) imager consists of a thin slab of high-resistivity silicon which is flip-chip bonded using indium bumps to a Rockwell PICNIC CMOS multiplexer. Unlike more common CMOS imagers, the flip-chip bonding of the HYVISI provides 100% fill factor. The high-resistivity silicon provides high QE over the soft X-ray bandpass, while the multiplexer provides high level electronic integration. The detector has an amplifier per pixel, and various readout modes. The readout modes include the possibility of selecting arbitrary regions of interest and Fowler sampling to decrease noise and improve energy performance. We report on read noise, QE, and energy resolution, and on the effectiveness of multiple reads for noise reduction. We discuss future directions for this very promising technology which would make it ideal for use as an astronomical imaging spectrometer in the soft X-ray band.

Performance and calibration of the AXAF High-Resolution Camera I: imaging readout

The high resolution camera (HRC) will be one of the two focal plane instruments on the Advanced X-ray Astrophysics Facility, (AXAF). AXAF will perform high resolution spectrometry and imaging in the X-ray band of 0.1 to 10 keV. The HRC instrument consists of two detectors, the HRC-I for imaging and the HRC-S for spectroscopy. Each HRC detector consists of a thin aluminized polyimide window, a chevron pair of microchannel plates (MCPs) and a crossed grid charge readout. The HRC-I is a 100 by 100 mm detector optimized for high resolution imaging and timing, the HRC-S is an approximately 30 by 300 mm detector optimized to function as the readout for the low energy transmission grating spectrometer (LETGS). In this paper we present the absolute quantum efficiency, spatial resolution, point spread response function and count rate linearity of the HRC-I detector. Data taken at the HRC laboratory and at the Marshall Space Flight Center X-ray Calibration Facility are presented. The development of the HRC is a collaborative effort between The Smithsonian Astrophysical Observatory, University of Leicester UK and the Osservatorio Astronomico, G.S. Vaiana, Palermo Italy.

Absolute quantum efficiency calibration of the AXAF High-Resolution Camera

We discuss the current status of the Advanced X-ray Astrophysics Facility (AXAF) High Resolution Camera (HRC) quantum efficiency (QE) calibration. The absolute quantum efficiency of flight candidate, CsI coated HRC microchannel plates (MCPs) for the imaging detector (HRC-I) manufactured by Galileo Electro-Optics Corporation (GEOC) has been measured at several energies. We find the absolute QE of these MCPs (measured at SAO) to be 0.41 at C Kalpha (E equals 277 eV) and 0.28 at Al Kalpha (E equals 1487) eV). The absolute QE of flight-like HRC-I MCPs manufactured by Phillips Components (measured at the University of Leicester) is approximately 0.40 at both C Kalpha and Si Kalpha (E equals 1739 eV). We are now in the process of measuring the absolute QE of both the HRC-I and HRC-S flight detectors at 22 different energies at 4 azimuthal and 5 polar angles. A summary of planned measurements is presented. In addition, we present data taken at the Daresbury Synchrotron Radiation Source to map out the detailed edge structure of the MCP glass and coatings. In particular, we present measurements of the relative QE of CsI coated MCPs around Cs and I M edges, and absolute measurements around the K K and Cs LIII edges. The absolute measurements of the flight instrument at the 22 discrete energies will be combined with the relative synchrotron measurements of flight-like detectors to produce the absolute QE of the HRC over the entire AXAF bandpass (0.1 to 10 keV).

Measurement of the transmission of the UV/ion shields for the AXAF High-Resolution Camera

The Advanced X-ray Astrophysics Facility (AXAF) is scheduled for launch in summer/fall 1998. One of its two focal plane instruments is the high resolution camera (HRC). The HRC consists of two detectors; an imaging detector (HRC-I) and a detector (HRC-S) for the spectroscopic read-out of the low energy transmission grating (LETG). Both detectors are comprised of a chevron pair of microchannel plates with a crossed grid charge detector (CGCD) and a UV/ion shield (UVIS). Each UVIS is mounted as a free standing window in front of the MCPs. The HRC-I UVIS is 10 cm multiplied by 10 cm and consists of 5000 angstrom polyimide, one side of which is coated with 700 angstrom aluminum. The other side is coated with 200 angstroms of carbon. The HRC-S UVIS consists of three 3 cm multiplied by 10 cm segments. The thickness of the polyimide film (2000 - 2500 angstrom) and of the aluminum coating (300 - 2000 angstrom) of each segment has been varied to optimize the shields performance with the LETG. In this paper, x-ray transmission models are presented. Results of laboratory x-ray transmission measurements of the flight HRC-I UVIS at various energies in the range of 0.1 to 1.5 keV, as well as results of x-ray transmission measurements of a flight UVIS-I witness sample, are discussed. Results of UV transmission measurements of a flight UVIS-I witness sample also are presented.

Microchannel plate testing and evaluation for the AXAF high-resolution camera (HRC)

The high resolution camera (HRC) will be one of the two focal plane instruments on the Advanced X-ray Astrophysics Facility (AXAF). AXAF is a major NASA space observatory and is scheduled for launch in 1998. The essential elements of the HRC instruments are chevron pairs of microchannel plates (MCPs). The HRC MCPs provide x ray conversion and electron multiplication while maintaining high spatial and temporal resolution. In addition, the HRC MCPs will be the largest format, the lowest internal background, and the highest resolution of any MCP-based x-ray imaging detector. This paper presents results obtained in testing and evaluating flight candidate MCPs with emphasis on their low internal background out-of-band (high energy) response and their spatial uniformity.