Hard X-ray mirrors for Nuclear Security

Technical Report · Thu Jan 07 00:00:00 EST 2016

DOI:https://doi.org/10.2172/1237572· OSTI ID:1237572

Descalle, M. A. ^[1]; Brejnholt, N. ^[1]; Hill, R. ^[1]; Decker, T. ^[1]; Alameda, J. ^[1]; Soufli, R. ^[1]; Pivovaroff, M. ^[1]; Pardini, T. ^[1]

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1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

Research performed under this LDRD aimed to demonstrate the ability to detect and measure hard X-ray emissions using multilayer X-ray reflective optics above 400 keV, to enable the development of inexpensive and high-accuracy mirror substrates, and to investigate applications of hard X-ray mirrors of interest to the nuclear security community. Experiments conducted at the European Synchrotron Radiation Facility demonstrated hard X-ray mirror reflectivity up to 650 keV for the first time. Hard X-ray optics substrates must have surface roughness under 3 to 4 Angstrom rms, and three materials were evaluated as potential substrates: polycarbonates, thin Schott glass and a new type of flexible glass called Willow Glass®. Chemical smoothing and thermal heating of the surface of polycarbonate samples, which are inexpensive but have poor intrinsic surface characteristics, did not yield acceptable surface roughness. D263 Schott glass was used for the focusing optics of the NASA NuSTAR telescope. The required specialized hardware and process were costly and motivated experiments with a modified non-contact slumping technique. The surface roughness of the glass was preserved and the process yielded cylindrical shells with good net shape pointing to the potential advantage of this technique. Finally, measured surface roughness of 200 and 130 μm thick Willow Glass sheets was between 2 and 2.5 A rms. Additional results of flexibility tests and multilayer deposition campaigns indicated it is a promising substrate for hard X-ray optics. The detection of U and Pu characteristics X-ray lines and gamma emission lines in a high background environment was identified as an area for which X-ray mirrors could have an impact and where focusing optics could help reduce signal to noise ratio by focusing signal onto a smaller detector. Hence the first one twelvetant of a Wolter I focusing optics for the 90 to 140 keV energy range based on aperiodic multilayer coating was designed. Finally, we conducted the first demonstration that reflective multilayer mirrors could be used as diagnostic for HED experiment with an order of magnitude improvement in signal-to-noise ratio for the multilayer optic compared a transmission crystal spectrometer.

• Research Organization: Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC52-07NA27344
• OSTI ID: 1237572
• Report Number(s): LLNL-TR-680582; TRN: US1600525
• Country of Publication: United States
• Language: English

Related Subjects

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
36 MATERIALS SCIENCE
98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL PROTECTION
HARD X RADIATION
KEV RANGE 100-1000
ROUGHNESS
MIRRORS
POLYCARBONATES
OPTICS
SURFACES
GLASS
LAYERS
SIGNAL-TO-NOISE RATIO
SUBSTRATES
FLEXIBILITY
REFLECTIVITY
SECURITY
COMPARATIVE EVALUATIONS
CYLINDERS
EMISSION
X-RAY SPECTRA
GAMMA SPECTRA
FOCUSING
SPECTROMETERS
COST
DEPOSITION
DETECTION
HEATING
SHAPE
SHEETS
SHELLS
COATINGS
URANIUM
PLUTONIUM