Search

We have fabricated multilayer reflectors of molybdenum-carbon, molybdenum-silicon, and nickel-carbon for x rays of 1-200 Å with an electron beam evaporation method in ultrahigh vacuum. The multilayers were deposited on flat and figured substrates of float glass and superpolished glass with a surface roughness of 2-3 Å (rms). The thickness of a layer pair and the number of layer pairs were 30-100 Å and 10-20, respectively. The x-ray characteristics of these multilayer reflectors were evaluated in the 1.5-200 Å region with characteristic x rays (CuKα, Si-Kα, A1-Kα, and C-Kα) and monochromatized synchrotron radiation. Peak reflectivities of molybdenum-carbon were found to be 70% at Cu-Kα and 40% at Al-Kα in grazing incidence and those of molybdenum-silicon to be more than 30% in the 150-170 Å band in near-normal incidence. On the basis of these experimental results, the x-ray optical properties of multilayers are discussed. [ABSTRACT FROM AUTHOR]

We propose and demonstrate a new clocking method for a charge-coupled device (CCD). When a CCD is used for a photon counting detector of X-rays, its weak point is a limitation of its counting rate, because high counting rate makes non-negligible pile-up of photons. In astronomical usage, this pile-up is especially severe for an observation of a bright point-like object. One typical idea to reduce the pile-up is a parallel sum (P-sum) mode. This mode completely loses one-dimensional information. Our new clocking method, panning mode, provides complementary properties between the normal mode and the P-sum mode. We performed a simple simulation in order to investigate a pile-up probability and compared the simulated result and actual obtained event rates. Using this simulation and the experimental results, we compared the pile-up tolerance of various clocking modes including our new method and also compared their other characteristics.

We fabricated a novel x-ray polarimeter with a transmission multilayer and measured its performance with synchrotron radiation. A self standing multilayer with seven Mo/Si bilayers was installed with an incident angle of 45 degrees in front of a back-illuminated CCD. The multilayer can be rotated around the normal direction of the CCD keeping an incident angle of 45 degrees. This polarimeter can be easily installed along the optical axis of x-ray optics. By using the CCD as a photon counting detector with a moderate energy resolution, the polarization of photons in a designed energy band can be measured along with the image. At high photon energies, where the multilayer is transparent, the polarimeter can be used for imaging and spectroscopic observations. We confirmed a modulation factor of 45% with 45% and 17% transmission for P- and S-polarization, respectively.