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R. Bruni

Bio: R. Bruni is an academic researcher from Harvard University. The author has contributed to research in topics: X-ray optics & X-ray telescope. The author has an hindex of 8, co-authored 30 publications receiving 181 citations.

Papers
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Proceedings ArticleDOI
TL;DR: In this paper, a prototype Eletroformed-Nickel-Replicated (ENR) mirror module is presented for the Constellation-X mission, which consists of 5 shells of diameters from 150 mm to 280 mm and of 426 mm total length.
Abstract: The Constellation-X mission, planned for launch in 2011, will feature an array of hard-x ray telescopes with a total collecting area goal of 1500 square centimeters at 40 keV. Various technologies are currently being investigated for the optics of these telescopes including multilayer-coated Eletroformed-Nickel-Replicated (ENR) shells. The attraction of the ENR process is that the resulting full-shell optics are inherently stable and offer the promise of good angular resolution and enhanced instrument sensitivity. The challenge for this process is to meet a relatively tight weight budget with a relatively dense material (rho nickel = 9 grams per cubic centimeters.) To demonstrate the viability of the ENR process we are fabricating a prototype HXT mirror module to be tested against a competing segmented-glass-shell optic. The ENR prototype will consist of 5 shells of diameters from 150 mm to 280 mm and of 426 mm total length. To meet the stringent weight budget for Con-X, the shells will be only 150 micron thick. The innermost of these will be coated with Iridium, while the remainder will be coated with graded-density multilayers. Mandrels for these shells are currently under fabrication (Jan 03), with the first shells scheduled for production in February 03. A tentative date of late Summer has been set for prototype testing. Issues currently being addressed are the control of stresses in the multiplayer coating and ways of mitigating their effects on the figure of the necessarily thin shells. Also, the fabrication, handling and mounting of these shells without inducing permanent figure distortions. A full status report on the prototype optic will be presented along with test results as available.

27 citations

Proceedings ArticleDOI
TL;DR: In this paper, a process to fabricate metal-ceramic replicated optics which will be lighter weight than current nickel replicated technology is presented. But this process is not suitable for X-ray astronomy missions, as it requires large diameter mirrors with thin cross sections allowing maximum nesting and increase in collecting area.
Abstract: NASA’S future X-ray astronomy missions will require X-ray optics that have large effective area while remaining lightweight, and cost effective. Some X-ray missions, such as XMM-Newton[1] , and the upcoming Spectrum-Rontgen- Gamma[2] mission use an electroformed nickel replication (ENR) process[3] to fabricate the nested grazing incidence X-ray telescope mirror shells for an array of moderate resolution, moderate effective area telescopes. We are developing a process to fabricate metal-ceramic replicated optics which will be lighter weight than current nickel replicated technology. Our technology development takes full advantage of the replication technique by fabricating large diameter mirrors with thin cross sections allowing maximum nesting and increase in collecting area. This will lead to future cost effective missions with large effective area and lightweight optics with good angular resolution. Recent results on fabrication and testing of these optics is presented.

14 citations

Proceedings ArticleDOI
TL;DR: In this article, the first results concerning the effect of high-density materials on the reflectivity of X-ray observations were presented at the photon energies of 200 eV (i.e. below the carbon K absorption edge).
Abstract: In X-ray astronomical telescopes, the focalization of the radiation is achieved by means of grazing incidence Wolter I (parabola + hyperbola) optics in total reflection regime. In general, high density materials (e.g. Au, Pt, Ir, W) are used as reflecting coatings, in order to increase as much as possible the cut-off angles and energies for total reflection. However these materials present an important reduction of the reflectivity between 0.2 and 5 keV, due to the photoabsorption, and this phenomenon is particularly enhanced in correspondence of the M absorption edges (between 2 and 3.5 keV). In general, this determines a strong decrease of the telescope effective area. To overcome the problem we suggested in previous works the coating of the mirror surface by a low-density material such as carbon. Mirror samples with different coatings made by high density materials: Au, Ir, Pt, and W with a carbon overcoating were manufactured and reflectivity data in the soft X-ray band (100-2000 eV), performed both at the XACT facility in Palermo (Italy) and at BSRF synchrotron in Beijing (China), are showed. In this paper we present some of the first results concerning the measurements carried out at the photon energies of 200 eV (i.e. below the carbon K absorption edge) and 1280 eV (i.e. the region just below the heavy material M absorption edge).

14 citations

Proceedings ArticleDOI
Suzanne Romaine1, John E. Everett1, R. Bruni1, Adrian Ivan1, Paul Gorenstein1 
19 Nov 1998
TL;DR: In this paper, a multilayer coating of integral cylindrical optics is developed to focus hard x-ray optics for future X-ray astronomy missions, and the results from both longitudinal and azimuthal uniformity coating tests are presented.
Abstract: We are engaged in a program to develop focusing hard x-ray optics for future x-ray astronomy missions. Optics are being developed to focus x-rays up to and beyond 80 keV. Emphasis is on the multilayer coating of integral cylindrical optics which will provide the highest spatial resolution. A chamber geometry has been designed to allow the uniform coating of the inside surface of integral cylinders. The building and testing of this system has taken place over the past year. Linear DC magnetron cathodes are used to sputter the multilayer films. Initial results from both longitudinal and azimuthal uniformity coating tests are presented.

13 citations

Proceedings ArticleDOI
TL;DR: In this paper, the authors have shown how a thin layer of a light material, like carbon, on top of a traditional reflecting coating, can enhance the reflectivity in the soft x-ray spectral region (below 5 keV) without degrading the performances for higher energies.
Abstract: X-ray Wolter focusing telescopes concentrate the light by means of reflection on smooth surfaces at small grazing angle (below a couple of degrees). The traditional coatings for these kind of applications are heavy materials that, due to their high density, present a high critical energy for total reflection. Recent works have shown how a thin layer of a light material, like carbon, on top of a traditional reflecting coating, can enhance the reflectivity in soft x-ray spectral region (below 5 keV), without degrading the performances for higher energies. We presented at SPIE 2007 some experimental results about the reflectivity measurement at very low energies (200 eV) and rather large angles (1-2 deg). In the present work we extend the former study, by the realization of a new set of samples with coatings made of different materials (Pt, Au, W, Ir) and the measurement of their reflectivity for the typical angles (< 1°) and energies (1-10 keV) employed in astronomical grazing incidence telescopes.

12 citations


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Journal Article
TL;DR: The XMM-Newton Observatory is a cornerstone mission of the European Space Agency's Horizon 2000 programme, and is the largest scientific satellite it has launched to date as mentioned in this paper, which has been enabled by the unprecedentedly large effective area of the three mirror modules, which are briefly described.
Abstract: The XMM-Newton Observatory is a cornerstone mission of the European Space Agency's Horizon 2000 programme, and is the largest scientific satellite it has launched to date. This paper summarises the principal characteristics of the Observatory which are pertinent to scientific operations. The scientific results appearing in this issue have been enabled by the unprecedentedly large effective area of the three mirror modules, which are briefly described. The in-orbit performance and preliminary calibrations of the observatory are briefly summarised. The observations from the XMM-Newton calibration and performance verification phase, which are public and from which most papers in this issue have been derived, are listed. The flow of data from the spacecraft, through the ground segment, to the production of preliminary science products supplied to users is also discussed.

140 citations

Journal ArticleDOI
Daniel Sinars1, M. A. Sweeney1, C. S. Alexander1, D. J. Ampleford1  +185 moreInstitutions (3)
TL;DR: The 80-TW "Z" pulsed power facility at Sandia National Laboratories as discussed by the authors is the largest pulsed-power device in the world today, and it can discharge up to 22'MJ of energy stored in its capacitor banks into a current pulse that rises in 100'ns and peaks at a current as high as 30 MA in low-inductance cylindrical targets.
Abstract: Pulsed power accelerators compress electrical energy in space and time to provide versatile experimental platforms for high energy density and inertial confinement fusion science. The 80-TW “Z” pulsed power facility at Sandia National Laboratories is the largest pulsed power device in the world today. Z discharges up to 22 MJ of energy stored in its capacitor banks into a current pulse that rises in 100 ns and peaks at a current as high as 30 MA in low-inductance cylindrical targets. Considerable progress has been made over the past 15 years in the use of pulsed power as a precision scientific tool. This paper reviews developments at Sandia in inertial confinement fusion, dynamic materials science, x-ray radiation science, and pulsed power engineering, with an emphasis on progress since a previous review of research on Z in Physics of Plasmas in 2005.

127 citations

Journal ArticleDOI
TL;DR: In this article, the authors demonstrate neutron beam focusing by axisymmetric mirror systems based on a pair of mirrors consisting of a confocal ellipsoid and hyperboloid.
Abstract: We demonstrate neutron beam focusing by axisymmetric mirror systems based on a pair of mirrors consisting of a confocal ellipsoid and hyperboloid. Such a system, known as a Wolter mirror configuration, is commonly used in X-ray telescopes. The axisymmetric Wolter geometry allows nesting of several mirror pairs to increase collection efficiency. We implemented a system containing four nested Ni mirror pairs, which was tested by the focusing of a polychromatic neutron beam at the MIT Reactor. In addition, we have carried out extensive ray-tracing simulations of the mirrors and their performance in different situations. The major advantages of the Wolter mirrors are nesting for large angular collection and aberration-free performance. We discuss how these advantages can be utilized to benefit various neutron scattering methods, such as imaging, SANS, and time-of-flight spectroscopy.

48 citations

01 Dec 2010
TL;DR: In this article, the authors demonstrate neutron beam focusing by axisymmetric mirror systems based on a pair of mirrors consisting of a confocal ellipsoid and hyperboloid.
Abstract: We demonstrate neutron beam focusing by axisymmetric mirror systems based on a pair of mirrors consisting of a confocal ellipsoid and hyperboloid. Such a system, known as a Wolter mirror configuration, is commonly used in X-ray telescopes. The axisymmetric Wolter geometry allows nesting of several mirror pairs to increase collection efficiency. We implemented a system containing four nested Ni mirror pairs, which was tested by the focusing of a polychromatic neutron beam at the MIT Reactor. In addition, we have carried out extensive ray-tracing simulations of the mirrors and their performance in different situations. The major advantages of the Wolter mirrors are nesting for large angular collection and aberration-free performance. We discuss how these advantages can be utilized to benefit various neutron scattering methods, such as imaging, SANS, and time-of-flight spectroscopy.

46 citations

Journal ArticleDOI
TL;DR: In this article, an extension of the energy range, enabling calibrations of hard X-ray optics over a broad energy band beam (up to 50 keV), was reported.
Abstract: The Max-Planck-Institut fur extraterrestrische Physik (MPE) in Garching, Germany, uses its large X-ray beam line facility PANTER for testing X-ray astronomical instrumentation. A number of telescopes, gratings, filters, and detectors, e.g. for astronomical satellite missions like Exosat, ROSAT, Chandra (LETG), BeppoSAX, SOHO (CDS), XMM-Newton, ABRIXAS, Swift (XRT), have been successfully calibrated in the soft X-ray energy range (<15keV). Moreover, measurements with mirror test samples for new missions like ROSITA and XEUS have been carried out at PANTER. Here we report on an extension of the energy range, enabling calibrations of hard X-ray optics over the energy range 15–50 keV. Several future X-ray astronomy missions (e.g., Simbol-X, Constellation-X, XEUS) have been proposed, which make use of hard X-ray optics based on multilayer coatings. Such optics are currently being developed by the Osservatorio Astronomico di Brera (OAB), Milano, Italy, and the Harvard-Smithsonian Center for Astrophysics (CfA), Cambridge, MA, USA. These optics have been tested at the PANTER facility with a broad energy band beam (up to 50 keV) using the XMM-Newton EPIC-pn flight spare CCD camera with its good intrinsic energy resolution, and also with monochromatic X-rays between C-K (0.277 keV) and Cu-Kα (8.04 keV).

45 citations