High resolution X-ray spherically bent crystal spectrometer for laser-produced plasma diagnostics

A new high spectral resolution crystal spectrometer is designed to measure very low emissive X-ray spectra of laser-produced plasma in 0.5-0.9 nm range. A large open aperture （30 ×20 （mm）） mica （002） spherically bent crystal with curvature radius R = 380 mm is used as dispersive and focusing element. The imaging plate is employed to obtain high spectral resolution with effective area of 30 × 80 （mm）. The long designed path of the X-ray spectrometer beam is 980 mm from the source to the detector via the crystal. Experiment is carried out at a 20-J laser facility. X-ray spectra in an absolute intensity scale is obtained from Al laserproduced plasmas created by laser energy of 6.78 J. Samples of spectra obtained with spectral resolution of up to E/△E - 1500 are presented. The results clearly show that the device is good to diagnose laser high-density plasmas.

Multifractal modelling and spectrum analysis: Methods and applications to gamma ray spectrometer data from southwestern Nova Scotia, Canada

Multifractal spectrum, autocorrelation/semivariogram and power spectrum are three dif- ferent functions characterizing a field or measure from different aspects. These functions are interre- lated in such that the autocorrelation/semivariogram and power spectrum are related to the low order statistical moments (0 to 2 nd) which may determine the local multifractality (τ ″(1)) of a multifractal measure. A better understanding of the interrelationships among these three functions is important because, on one hand, the multifractal modelling characterizes a multifractal measure in a more de- tailed manner since it involves moments of all orders. On the other hand, the commonly used semivariogram and power spectrum functions can be used as alternatives to study the dominant mul- tifractal properties around the mean measure. Moreover, semivariogram and power-spectrum func- tions provide spatial and spectral information, which is highly valued in geological applications. A new fractal relation found between area and power-spectrum will be useful for investigation of new meth- ods of spatial-spectral analysis for pattern recognition, anomaly separation, classification, etc. These results have been demonstrated with the case study of modelling gamma ray spectrometer data from the mineral district, southwestern Nova Scotia, Canada. The results have shown that the values of uranium (U), thorium (Th) and potassium (K) may possess monofractal properties whereas the ratios of these values show high multifractality. The values of the ratios U/K and U/Th show relatively large variances and may provide more information for distinguishing the distinct phases of the granites, country rocks as well as possible gold mineralization-associated regional hydrothermal alteration zones. In addition, the power spectra for U, Th, K, U/Th and U/K consistently show two distinct power-law relationships for two ranges of wave number 12≤ω ≤160 km and 0≤ω ≤12 km. These properties might provide useful thresholds for separating the power-spectrum values into two types of patterns to reflect different influences of possible geological processes such as hydrothermal altera- tion in the study area.

Digital logarithmic airborne gamma ray spectrometer

A new digital logarithmic airborne gamma ray spectrometer is designed in this study. The spectrometer adopts a high-speed and high-accuracy logarithmic amplifier （LOGll4） to amplify the pulse signal logarithmically and to improve the utilization of the ADC dynamic range because the low-energy pulse signal has a larger gain than the high-energy pulse signal. After energy calibration, the spectrometer can clearly distinguish photopeaks at 239, 352, 583 and 609 keV in the low-energy spectral sections. The photopeak energy resolution of 137Cs improves to 6.75% from the original 7.8%. Furthermore, the energy resolution of three photopeaks, namely, K, U, and Th, is maintained, and the overall stability of the energy spectrum is increased through potassium peak spectrum stabilization. Thus, it is possible to effectively measure energy from 20 keV to 10 MeV.

Detection of the X-ray spectra of imploding neon Z-pinch with elliptically bent mica crystal spectrometer

A wide variety of X-ray and extreme ultraviolet diagnostics are being developed to study on Yang accelerator. An elliptically bent crystal spectrometer is designed with a focal length of 1350 mm. A mica crystal with an interplanar spacing of 1.984 nm bent onto an elliptical substrate with eccentricity of 0.9485 is used. The crystal analyzer covers the Bragg angle range from 30° to 60°. The mica crystal can efficiently reflect radiation in multiple orders, covering the entire spectral range from 0.1 to 1.73 nm except for a gap from 0.86 to 1.0 nm. The application experiment is performed on Yang accelerator using the bent mica crystal analyzer. Spectra of neon-puff Z-pinch plasmas are recorded with a X-ray film, showing the H-like and the He-like lines of neon. Each spectrum has been identified and used for the wavelength calibration, and most of the line radiation is contained in the He-α and the L-α lines. The experimental results have demonstrated that the spectral resolution approximates 379.

High-resolution X-ray focusing concave (elliptical) curved crystal spectrograph for laser-produced plasma

The X-ray spectrum emitted, from laser-produced plasma contains plentiful information. X-ray spectrometer is a powerful tool for plasma diagnosis and studying the information and evolution of the plasma. X-ray concave (elliptical) curved crystals analyzer was designed and manufactured to investigate the properties of laser-produced plasma. The experiment was carried out on Mianyang Xingguang-Ⅱ Facility and aimed at investigating the characteristics of a high density iron plasma. Experimental results using KAP, LIF, PET, and MICA curved crystal analyzers are described, and the spectra of Au, Ti laser-produced plasma are shown. The focusing crystal analyzer clearly gave an increase in sensitivity over a flat crystal.

Integration of GaN thin films with silicon substrates by fusion bonding and laser lift-off

GaN thin films grown on sapphire substrates by metalorganic chemical vapor deposition （MOCVD） are successfully bonded and transferred onto Si receptor substrates using fusion bonding and laser lift-off （LLO） technique. GaN/Al2O3 structures are joined to Si substrates by pressure bonding Ti/Au coated GaN surface onto Ti/Au coated Si receptor substrates at the temperature of 400℃. KrF excimer laser with 400-mJ/cm^2 energy density, 248-nm wavelength, and 30-ns pulse width is used to irradiate the wafer through the transparent sapphire substrates and separate GaN films from sapphire. Cross-section scanning electron microscopy （SEM） combined with energy dispersive X-ray spectrometer （EDS） measurements show that Au/Si solid solution is formed during bonding process. Atomic force microscopy （AFM） and photoluminescence （PL） measurements show that the qualities of GaN films on Si substrates degrade little after substrates transfer.

Development of superconducting microcalorimeters for the HUBS mission

Hot Universe Baryon Surveyor(HUBS)is a proposed space‐borne observatory for X‐ray astronomy.The primary scientific objectives of the mission are to fill a void in probing the ecosystem of galaxies and thus to advance our understanding of galaxy formation and evolution,which is of fundamental importance in cosmology.More specifically,HUBS aims at directly detecting soft X‐ray emission from diffuse gas of temperature exceeding 106 K,which is theoretically postulated to permeate the large structures in the cosmic web and also fill the extended halo of galaxies.However,although some indirect evidence exists,the presence of such hot gas has yet to be well established observationally,due to the lack of effective tools to probe it.In this paper,we describe the design of HUBS,focusing on its scientific payload,which employs superconducting technologies in the detector system,and particularly on progress in the development of superconducting microcalorimeters.