The source position determination method of the multiplexing lobster-eye optics (MuLE), which is a newly proposed configuration of the Lobster-Eye (LE) optics to reduce the number of focal plane detectors significantly, was developed. In the MuLE configuration, X-rays came from different field-of-views (FoVs) were focused on a single imager. To separate the multiplexed FoVs, the optics was designed so that cross-like responses of LE mirror in different FoVs had different azimuthal rotation angles. In this paper, we show the method to determine the rotation angles and verify the FoV discrimination power by using a ray tracing simulation. The configuration we assumed in the simulation was nine multiplexed FoVs projecting onto a single imager (nine-segment MuLE optics) with a 30 cm focal length and a 9×9 cm2 effective area of each LE segment. One LE segment covers 9.6°× 9.6° FoV and the total FoV of the nine-segment MuLE configuration was 9 times of that. Our method provided 100% correct FoV discrimination at the 5σ detection limit flux (35–70 mCrab) for a transient source with a duration of 100 s except for the edge of the FoV.
We present the first application of a time projection chamber polarimeter to measure high energy X-ray polarization above 10 keV. The polarimeter is designed based on the PRAXyS soft X-ray polarimeter. The sealed gas is changed to a gas mixture of 60% argon and 40% dimethyl ether at 1 atm to be sensitive to high energy X-rays. The polarimeter performance is verified with linearly polarized, monochromatic X-rays at a synchrotron radiation facility, KEK Photon Factory BL-14A. The measured modulation factors are 42.4 ± 0.6%, 50.4 ± 0.6%, and 55.0 ± 0.6% at 12, 14, and 16 keV, respectively, and the measured polarization angles are consistent with the expected values at all energies.
The coded aperture imaging technique is a useful method of x-ray imaging in observational astrophysics. However, the presence of imaging noise or so-called artifacts in a decoded image is a drawback of this method. We propose a coded aperture imaging method using multiple different random patterns for significantly reducing the image artifacts. This aperture mask contains multiple different patterns each of which generates a different artifact distribution in its decoded image. By summing all decoded images of the different patterns, the artifact distributions are cancelled out, and we obtain a remarkably accurate image. We demonstrate this concept with imaging experiments of a monochromatic 16-keV hard x-ray beam at the synchrotron photon facility SPring-8, using the combination of a complementary metal-oxide-semiconductor image sensor and an aperture mask that has four different random patterns composed of holes with a diameter of 27 μm and a separation of 39 μm. The entire imaging system is installed in a 25-cm-long compact size and achieves an angular resolution of <30 arc sec (full-width at half-maximum). In addition, we show by Monte Carlo simulation that the artifacts can be reduced more effectively if the number of different patterns increases to 8 or 16.
We propose a concept of multiplexing lobster-eye (MuLE) optics to achieve significant reductions in the number of focal plane imagers in lobster-eye (LE) wide-field x-ray monitors. In the MuLE configuration, an LE mirror is divided into several segments and the x-rays reflected on each of these segments are focused on a single image sensor in a multiplexed configuration. If each LE segment assumes a different rotation angle, the azimuthal rotation angle of a cross-like image reconstructed from a point source by the LE optics identifies the specific segment that focuses the x-rays on the imager. With a focal length of 30 cm and LE segments with areas of 10 × 10 cm2, ∼1 sr of the sky can be covered with 36 LE segments and only four imagers (with total areas of 10 × 10 cm2). A ray tracing simulation was performed to evaluate the nine-segment MuLE configuration. The simulation showed that the flux (0.5 to 2 keV) associated with the 5σ detection limit was ∼2 × 10 − 10 erg cm − 2 s − 1 (10 mCrab) for a transient with a duration of 100 s. The simulation also showed that the direction of the transient for flux in the range of 14 to 17 mCrab at 0.6 keV was determined correctly with a 99.7% confidence limit. We conclude that the MuLE configuration can become an effective on-board device for small satellites for future x-ray wide-field transient monitoring.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.