Supermirror hard-x-ray telescope

Yamashita, Koujun; Serlemitsos, P. J.; Tueller, J.; Barthelmy, S. D.; Bartlett, Lyle M.; Chan, Kai Wing; Furuzawa, Akihiro; Gehrels, N.; Haga, Kazuo; Kunieda, H.; Kurczynski, Peter; Lodha, G. S.; Nakajo, Norio; Nakamura, N.; Namba, Yoshiharu; Ogasaka, Yasushi; Okajima, Takashi; Palmer, D. M.; Parsons, A.; Soong, Yang; Stahl, C.M.; Takata, Harumi; Tamura, Kouichi; Tawara, Yuzuru; Teegarden, B. J.

doi:10.1364/ao.37.008067

Cited by 85 publications

(45 citation statements)

References 7 publications

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“…The results presented here showing high reflectance at hard x-ray energies up to 200 keV indicate that depth-graded W/Si multilayer coatings can be used for practical hard x-ray reflectors, and in particular for the new generation of hard x-ray astronomical telescopes currently being developed [1][2][3][4] that are designed to operate at energies below 100 keV, and possibly for future telescopes designed to operate at energies in excess of 100 keV. High quality films can be deposited by ͑low-pressure͒ magnetron sputtering, a deposition technique that is easily scaled for large area coatings.…”

Section: Discussionmentioning

confidence: 99%

Growth, structure, and performance of depth-graded W/Si multilayers for hard x-ray optics

Windt

Christensen

Craig

et al. 2000

Journal of Applied Physics

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We describe the development of depth-graded W/Si multilayer films prepared by magnetron sputtering for use as broad-band reflective coatings for hard x-ray optics. We have used specular and nonspecular x-ray reflectance analysis to characterize the interface imperfections in both periodic and depth-graded W/Si multilayer structures, and high-resolution transmission electron microscopy ͑TEM͒ and selected area electron diffraction ͑SAED͒ to characterize the interface structure and layer morphology as a function of depth in an optimized depth-graded multilayer. From x-ray analysis we find interface widths in the range ϭ0.275-0.35 nm for films deposited at low argon pressure ͑with a slight increase in interface width for multilayers having periods greater than ϳ20 nm, possibly due to the transition from amorphous to polycrystalline metal layers identified by TEM and SAED͒, and somewhat larger interface widths ͑i.e., ϭ0.35-0.4 nm͒ for structures grown at higher Ar pressures, higher background pressures, or with larger target-to-substrate distances. We find no variation in interface widths with magnetron power. Nonspecular x-ray reflectance analysis and TEM suggest that the dominant interface imperfection in these films is interfacial diffuseness; interfacial roughness is minimal ( r ϳ0.175 nm) in structures prepared under optimal conditions, but can increase under conditions in which the beneficial effects of energetic bombardment during growth are compromised. X-ray reflectance analysis was also used to measure the variation in the W and Si deposition rates with bilayer thickness: we find that the W and Si layer thicknesses are nonlinear with the deposition times, and we discuss possible mechanisms responsible for this nonlinearity. Finally, hard x-ray reflectance measurements made with synchrotron radiation were used to quantify the performance of optimized depth-graded W/Si structures over the photon energy range from 18 to 212 keV. We find good agreement between the synchrotron measurements and calculations made using either 0.3 nm interface widths, or with a depth-graded distribution of interface widths in the range ϭ0.275-0.35 nm ͑as suggested by 8 keV x-ray and TEM analyses͒ for a structure containing 150 bilayers, and designed for high reflectance over the range 20 keV ϽEϽ70 keV. We also find for this structure good agreement between reflectance measurements and calculations made for energies up to 170 keV, as well as for another graded W/Si structure containing 800 bilayers, designed for use above 100 keV, where the peak reflectance was measured at Eϭ212 keV to be Rϭ76.5Ϯ4% at a graze angle of ϭ0.08°.

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Section: Discussionmentioning

confidence: 99%

Growth, structure, and performance of depth-graded W/Si multilayers for hard x-ray optics

Windt

Christensen

Craig

et al. 2000

Journal of Applied Physics

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“…Low noise readout system for the scatterer is also the key to realize not only good angular resolution but also lower detection threshold. The lower energy coverage is prefered to connect the band pass of Compton telescope with that of the technology using hard X-ray focusing mirror optics [12].…”

Section: Introductionmentioning

confidence: 99%

Recent results from a Si/CdTe semiconductor Compton telescope

Tanaka

Watanabe

Takeda

et al. 2006

Nuclear Instruments and Methods in Physics Research Section A:

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We are developing a Compton telescope based on high resolution Si and CdTe detectors for astrophysical observations in sub-MeV/MeV gamma-ray region. Recently, we constructed a prototype Compton telescope which consists of six layers of double-sided Si strip detectors and CdTe pixel detectors to demonstrate the basic performance of this new technology. By irradiating the detector with gamma-rays from radio isotope sources, we have succeeded in Compton reconstruction of images and spectra. The obtained angular resolution is 3.9 • (FWHM) at 511 keV, and the energy resolution is 14 keV (FWHM) at the same energy. In addition to the conventional Compton reconstruction, i.e., drawing cones in the sky, we also demonstrated a full reconstruction by tracking Compton recoil electrons using the signals detected in successive Si layers. By irradiating 137 Cs source, we successfully obtained an image and a spectrum of 662 keV line emission with this method. As a next step, development of larger double-sided Si strip detectors with a size of 4 cm × 4 cm is underway to improve the effective area of the Compton telescope. We are also developing a new low-noise analog ASIC to handle the increasing number of channels. Initial results from these two new technologies are presented in this paper as well.

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“…Yamashita et al 1998;Ogasaka et al 2000;Craig et al 1998;Hussain et al 1999;Mao et al 1999). In principle such techniques can focus radiation of even higher energies, though the number of layers for efficient reflection would become very large and the grazing angles very small, so the area of coated surface for a given effective area would be huge.…”

Section: Background and Contextmentioning

confidence: 99%

Diffractive/refractive optics for high energy astronomy

Skinner

2001

A&A

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Abstract.Diffractive optics components such as Fresnel Zone Plates and their derivatives potentially form the basis for telescope systems for X-ray and gamma-ray astronomy with high sensitivity and superb angular resolution. The main problem is that systems with convenient design parameters involve very long focal lengths. The design considerations and performance of telescopes using a simple Phase Fresnel Lens on one spacecraft and a detector assembly on another are considered. Such systems are shown to have the potential to provide orders of magnitude improvement on currently available sensitivity. At the same time the angular resolution can be at the micro arcsecond level or better -sufficient to resolve the structure surrounding the event horizon of black holes in nearby galaxies.

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Supermirror hard-x-ray telescope

Cited by 85 publications

References 7 publications

Growth, structure, and performance of depth-graded W/Si multilayers for hard x-ray optics

Growth, structure, and performance of depth-graded W/Si multilayers for hard x-ray optics

Recent results from a Si/CdTe semiconductor Compton telescope

Diffractive/refractive optics for high energy astronomy

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