Showing papers by "Michael J. Pivovaroff published in 2012"

Fundamental Physics at the Intensity Frontier

Abstract: The Proceedings of the 2011 workshop on Fundamental Physics at the Intensity Frontier. Science opportunities at the intensity frontier are identified and described in the areas of heavy quarks, charged leptons, neutrinos, proton decay, new light weakly-coupled particles, and nucleons, nuclei, and atoms.

The International Axion Observatory (IAXO)

Abstract: I. G. Irastorza, F. T. Avignone, G. Cantatore, S. Caspi, J. M. Carmona, T. Dafni, M. Davenport, A. Dudarev, G. Fanourakis, E. Ferrer-Ribas, J. Galan, J. A. Garcia, T. Geralis, I. Giomataris, S. Gninenko, H. Gomez, D. H. H. Hoffmann, F. J. Iguaz, K. Jakovcic, M. Krcmar, B. Lakic, G. Luzon, A. Lindner, M. Pivovaroff, T. Papaevangelou, G. Raffelt, J. Redondo, A. Rodŕiguez, S. Russenschuck, J. Ruz, I. Shilon, H. Ten Kate, A. Tomas, S. Troitsky, K. van Bibber, J. A. Villar, J. Vogel, L. Walckiers, K. Zioutas Laboratorio de Fisica Nuclear y Astroparticulas, Universidad de Zaragoza, Zaragoza, Spain Department of Physics and Astronomy, University of South Carolina, Columbia, SC, USA Instituto Nazionale di Fisica Nucleare (INFN), Sezione di Trieste and Universita di Trieste, Trieste, Italy Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA CERN, Geneva, Switzerland National Center for Scientific Research Demokritos, Athens, Greece IRFU, Centre d’Etudes Nucleaires de Saclay (CEA-Saclay), Gifsur-Yvette, France Technische Universitat Darmstadt, IKP, Darmstadt, Germany Rudjer Boskovic Institute, Zagreb, Croatia Lawrence Livermore National Laboratory, Livermore, CA, USA DESY, Hamburg, Germany Max-Planck-Institut fur Physik, Munich, Germany Physics Department, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel Institute for Nuclear Research (INR), Russian Academy of Sciences, Moscow, Russia Naval Postgraduate School, Monterey, CA, USA University of Patras, Patras, Greece

NuSTAR on-ground calibration: I. Imaging quality

Abstract: The Nuclear Spectroscopic Telescope Array (NuSTAR) launched in June 2012 carries the first focusing hard Xray (5 - 80 keV) telescope to orbit. The on-ground calibration was performed at the RaMCaF facility at Nevis, Columbia University. During the assembly of the telescopes, mechanical surface metrology provided surface maps of the reflecting surfaces. Several flight coated mirrors were brought to BNL for scattering measurements. The information from both sources is fed to a raytracing code that is tested against the on-ground calibration data. The code is subsequently used for predicting the imaging properties for X-ray sources at infinite distance.

The International Axion Observatory (IAXO)

Abstract: The International Axion Observatory (IAXO) is a new generation axion helioscope aiming at a sensitivity to the axion-photon coupling of a few 10$^{12}$ GeV$^{-1}$, i.e. 1 - 1.5 orders of magnitude beyond the one currently achieved by CAST. The project relies on improvements in magnetic field volume together with extensive use of x-ray focusing optics and low background detectors, innovations already successfully tested in CAST. Additional physics cases of IAXO could include the detection of electron-coupled axions invoked to solve the white dwarfs anomaly, relic axions, and a large variety of more generic axion-like particles (ALPs) and other novel excitations at the low-energy frontier of elementary particle physics. This contribution is a summary of our paper [1] to which we refer for further details.

Review of substrate materials, surface metrologies and polishing techniques for current and future-generation EUV/x-ray optics

Abstract: This manuscript presents a review of recent advances in EUV/x-ray substrate specification, fabrication and metrology for photolithography, synchrotron sources, free-electron laser sources, solar physics and astronomy. Highlights from ultra-low- expansion glass substrates, silicon and silicon carbide substrates are presented. Selected emerging substrate materials and fabrication technologies are also discussed.

Cross comparison of surface slope and height optical metrology with a super-polished plane Si mirror

Abstract: We report on a cross-comparison of low-spatial-frequency su rface slope and height metrology with a super-polished flat X-ray mirror Si substrate fabricated for the Stanford Linear Acceler ator Center Linac Coherent Light Source hard X-ray mirror system HOMS-3. The substrate with overall dimensions of 450 × 30 × 50 mm 3 was specified to have a radius of curvature between 150 km and 195 km with a residual (after subtraction of the best-fit cylinder) slope variation on the level of 0.1 µrad rms, when measured in the tangential direction over a clear aperture of 380 × 5 mm 2 . Surface slope metrology with an accuracy of better than 60 nrad rms was performed with an upgraded long trace profiler LTP-II and an auto-collimator-based developmental LTP (DLTP). The instruments are available at Advanced Light Source optical metrology laboratory. Surface figure in the height domain was characterized at the Lawrence Livermore National Laboratory X-ray science and technology group with a large field-of-view ZYGO

A soft x-ray beam-splitting multilayer optic for the NASA GEMS Bragg Reflection Polarimeter

Abstract: A soft X-ray, beam-splitting, multilayer optic has been developed for the Bragg Reflection Polarimeter on the NASA Gravity and Extreme Magnetism Small Explorer Mission (GEMS). The optic is designed to reflect 0.5 keV X-rays through a 90 degree angle to the BRP detector, and transmit 2-10 keV X-rays to the primary polarimeter. A transmission requirement prevents the use of a thick substrate, so a 2 µm thick polyimide membrane was used. Atomic force microscopy has shown the membrane to possess high spatial frequency roughness less than 0.2 nm rms, permitting adequate X-ray reflectance. A multilayer thin film was especially developed with reflectance and transmission properties that satisfy the BRP requirements and with near-zero stress. Multilayer depositions for prototype reflectors have been performed via magnetron sputtering. Reflectivity and transmission measurements closely match theoretical predictions, both before and after rigorous environmental testing.

Application of an EMCCD camera for calibration of hard X-ray telescopes

Abstract: Recent technological innovations make it feasible to construct efficient hard x-ray telescopes for space-based astronomical missions. Focusing optics are capable of improving the sensitivity in the energy range above 10 keV by orders of magnitude compared to previously used instruments. The last decade has seen focusing optics developed for balloon experiments and they are implemented in approved space missions such as the Nuclear Spectroscopic Telescope Array (NuSTAR). The full characterization of x-ray optics for astrophysical missions, including measurement of the point spread function (PSF) as well as scattering and reflectivity properties of substrate coatings, requires a large area detector with very high spatial resolution and sensitivity, photon counting and energy discriminating capability. Novel back-thinned Electron Multiplying Charge-Coupled Devices (EMCCDs) are suitable detectors for ground-based calibrations if combined with a scintillating material. This optical coupling of the EMCCD chip to a microcolumnar CsI(Tl) scintillator can be achieved via a fiberoptic taper. Not only does this detector system exhibit low noise and high spatial resolution inherent to CCDs, but the EMCCD is also able to handle high frame rates. Additionally, thick CsI(Tl) yields high detection efficiency for x-rays. In this paper, we discuss the advantages of using an EMCCD to calibrate hard x-ray optics. We will illustrate the promising features of this detector solution using examples of data obtained during the ground calibration of the NuSTAR telescopes performed at Columbia University during 2010/2011. Finally, we give an outlook on latest development and optimizations.

Conceptual design of a grazing incidence x-ray deformable mirror using voice-coil actuators

Abstract: High-energy beams of X-rays used in studies of molecular structure have imperfect wavefront quality. Improved point-spread functions can in principle be made by adjustment of a deformable mirror (DM) in the beam train. Conventional DMs are unsuitable because they are not intended for use at the necessary grazing incidence angles, and the optical surface is not sufficiently stable. We describe the conceptual design for a new DM that addresses the requirements of this application. Our design draws on successful strategies employed in the adaptive secondary mirrors at the MMT and LBT telescopes, including the use of voice-coil actuators with collocated capacitive position sensors.

Simulating wavefront correction via deformable mirrors at x-ray beamlines

Abstract: Deformable mirrors (DMs) have been successfully used in astronomical adaptive optics at visible and near-infrared wavelengths, greatly reducing atmospheric-induced aberrations. Building upon the extensive techniques and methods developed for these applications, we propose to extend this capability to the soft and hard x-ray regime in order to take full advantage of the beam quality characteristic of new facilities such as the National Synchrotron Light Source (NSLS-II), and the Linac Coherent Light Source (LCLS). Achieving this goal challenges both current mirror manufacturing techniques and wavefront propagation modeling. Lawrence Livermore National Laboratory (LLNL), in collaboration with Northrop Grumman AOA Xinetics Inc., is currently developing an x-ray deformable mirror to correct for wave-front aberrations introduced along the beam path of a typical x-ray beamline. To model the expected performance of such a mirror, we have developed a simulation based on the wavefront propagation code PROPER. We will present the current implementation of the software, which models actuation of a deformable mirror and evaluates its effect on wavefront correction.

An examination of the sensitivity and systematic error of the NASA GEMS Bragg Reflection Polarimeter using Monte-Carlo simulations

Abstract: The Bragg Reflection Polarimeter (BRP) on the NASA Gravity and Extreme Magnetism Small Explorer Mission is designed to measure the linear polarization of astrophysical sources in a narrow band centered at about 500 eV. X-rays are focused by Wolter I mirrors through a 4.5 m focal length to a time projection chamber (TPC) polarimeter, sensitive between 2{10 keV. In this optical path lies the BRP multilayer reflector at a nominal 45 degree incidence angle. The reflector reflects soft X-rays to the BRP detector and transmits hard X-rays to the TPC. As the spacecraft rotates about the optical axis, the reflected count rate will vary depending on the polarization of the incident beam. However, false polarization signals may be produced due to misalignments and spacecraft pointing wobble. Monte-Carlo simulations have been carried out, showing that the false modulation is below the statistical uncertainties for the expected focal plane offsets of <~ 2 mm.

Conceptual design for a deformable mirror for use with X-ray sources

Abstract: High-energy beams of X-rays used in studies of molecular structure typically have imperfect wavefront quality. Improved point-spread functions can in principle be made by adjustment of a deformable mirror (DM) in the beam train. Conventional DMs are unsuitable because they are not intended for use at the necessary grazing incidence angles, and the optical surface is not sufficiently stable. We describe the conceptual design for a new DM that addresses the requirements of this application. Our design draws on successful strategies employed in the adaptive secondary mirrors at the MMT and LBT telescopes, including the use of voice-coil actuators with collocated capacitive position sensors.