High resolution speckle interferometry using virtual speckle pattern produced by information of deformation process

A high resolution new fringe analysis method for ESPI with only one camera is proposed by using features of speckle interferometry in a deformation process of a measured object. The profile of intensity of each speckle of the speckle patterns in the deformation process is analyzed by the Hilbert transform. A virtual speckle pattern for creating a carrier fringe image is produced artificially by using the information of profiles of intensities of speckles. The deformation map of the measured object can be detected by the virtual speckle pattern in an operation based on the spatial fringe analysis method. Experimental results show that the difference between the results by the new and the ordinary methods is 0.1 rad as standard deviation. From the results, it is confirmed that the high resolution measurement can be performed by this method the same as compared to the ordinary measurement method which needs to employ three speckle patterns.     

Internal reflection sensors with high angular resolution

We discuss the use of total internal reflection for the production of sensors with high angular resolution. These sensors are intended for measurement of the angle between a sensor's axis and the direction to a source of radiation or reflecting object. Sensors of this type are used in controlling the position of machine parts in robotics and industry, orienting space vehicles and astronomic devices in relation to the Sun, and as autocollimators for checking angles of deviation. This kind of sensor was used in the Apollo space vehicle some 20 years ago. Using photodetectors with linear and area CCD arrays has opened up new application possibilities for appropriately designed sensors. A generalized methodology is presented applicable to a wide range of tasks. Some modifications that can improve the performance of the basic design are described.     

Determination of the coherent scattering length of carbon using neutron interferometry

Highly oriented pyrolytic graphite samples were used for determining the coherent scattering length of the bound carbon atom by means of neutron interferometry. The value of 6.647±0.005 fm agrees well with results obtained by various other techniques.     

Energy and angular dependence of active-type personal dosemeter for high-energy neutron

In order to develop an active-type personal dosemeter having suitable sensitivity to high-energy neutrons, the characteristic response of silicon surface barrier detector has been investigated experimentally and theoretically. An agreement of the shape of pulse-height distribution, its change with radiator thickness and the relative sensitivity was confirmed between the calculated and experimental results for 14.8-MeV neutrons. The angular dependence was estimated for other neutron energies, and found that the angular dependence decreased with the incident energy. The reason was also discussed with regard to the radiator thickness relative to maximum range of recoil protons.     

Calibration of a neutron time-of-flight multidetector system for an intensity interferometry experiment

We present the details of an experiment on light particle interferometry. In particular, we focus on a time-of-flight technique which uses a cyclotron RF signal as a start and a liquid scintillator time signal as a stop, to measure neutron energy in the range of E_n≈1.8–$\text{150}\text{MeV}$. This dynamic range (up to $\text{300}\text{ns}$) is much larger than the beam bunch separation $\text{(54}\text{ns}\text{)}$ of the AGOR cyclotron (KVI). However, the problem of a short burst period is overcome by using the time information obtained from a fast projectile fragment phoswich detector. The complete analysis procedure to extract the final neutron kinetic energy spectra, is discussed.     

High resolution drift cells

We have built two test chambers, each 1 m long, containing quadratic and hexagonal cells which form approximately cylindrical drift fields. The chambers were filled with a gas mixture of carbon dioxide plus isobutan. They were read out with TDCs and with flash ADCs, alternatively. We arrive at space resolutions of 30 μm at atmospheric pressure and of ～ 25 μm at 2 bar pressure within the central part of the total drift length.     

High resolution frequency-domain reflectometry

A high-resolution method for the estimation of the position and magnitude of reflections from frequency-domain measurements is presented. The technique can tackle problems where Fourier-transform-based analysis fails. The connection between high-resolution frequency-domain reflectometry (FDR) and the estimation of the parameters of complex sinusoids with known phase is shown. A suitable algorithm is outlined, and its performance is evaluated analytically and through simulation. To demonstrate its practical applicability, the method is tested on vector network analyzer (VNA) measurements of a coaxial transmission line with a nonuniform dielectric     

High resolution drift chambers

High precision drift chambers capable of achieving ≤ 50 μm resolutions are discussed. In particular, we compare so-called cool and hot gases, various charge collection geometries, several timing techniques and we also discuss some systematic problems. We also present what we would consider an “ultimate” design of the vertex chamber.     

High resolution electron tomography

Reaching atomic resolution in 3D has been the ultimate goal in the field of electron tomography for many years. Significant progress, both on the theoretical as well as the experimental side has recently resulted in several exciting examples demonstrating the ability to visualise atoms in 3D. In this paper, we will review the different steps that have pushed the resolution in 3D to the atomic level. A broad range of methodologies and practical examples together with their impact on materials science will be discussed. Finally, we will provide an outlook and will describe future challenges in the field of high resolution electron tomography.     

A high resolution,low background fast neutron spectrometer

We discuss the possibility to create a spectrometer of full absorption based on liquid scintillator doped with enriched ${}^6$Li. Of specific interest, the spectrometer will have energy resolution estimated to lie in the range 5–10% for 14 MeV neutrons. It will be sensitive to fluxes from 10⁻⁴ to $\text{10}{}^6\text{cm}{}^{\mathrm{-2}}\text{s}{}^{\mathrm{-1}}$ above a threshold of 1 MeV in a γ-background of up to $\text{10}{}^4\text{s}{}^{\mathrm{-1}}$. The detector's efficiency will be determined by the volume of the scintillator only (∼3 l) and is estimated to be 0.2–10%. The main reason for the poor resolution of an organic scintillator based spectrometer of full absorption is a non-linear light-yield of the scintillator for recoil protons. The neutron energy is occasionally distributed among recoil protons, and due to non-linear light-yield the total amount of light from all recoil protons ambiguously determines the initial neutron energy. The high-energy resolution will be achieved by compensation of the non-linear light-yield of the scintillator through the use of optically separated sections. The applications of such a detector for low-background experiments in fundamental physics research, characterizations of neutron fluence in space, and the health physics community are discussed.     

The resolution function of a pulsed-source neutron chopper spectrometer

We introduce a formulation for the evaluation of the incident neutron intensity distribution for a chopper time-of-flight spectrometer at a pulsed neutron source. This treatment, incorporated with an assumed scattering function of the sample and the detector geometry, enables calculations of the shape of the time-of-flight intensity profiles of the incident and the scattered neutrons sensed by a neutron detector, thus providing direct comparison with experimental results. The resolution function, R(Q, E), is calculated for a nondispersive scatterer at a resonant energy E. The results of the calculations on the basis of this theory are substantiated by measured spectra obtained by the two chopper spectrometers, HRMECS and LRMECS, at the Argonne Intense Pulsed Neutron Source under a variety of experimental conditions. In all cases we find excellent agreement between calculations and experiments. Using these results we present a procedure for the determination of the mean incident neutron energy and the calibration of the energy-transfer scale for pulsed-source chopper spectrometers. These latter do not follow accurately from simple analysis, and are the main objects of this paper.     

LiF crystals as high spatial resolution neutron imaging detectors

Neutron imaging by color center formation in LiF crystals was applied to a sensitivity indicator (SI) as a standard samples for neutron radiography. The SI was exposed to a 5 mm pinhole-collimated thermal neutron beam with an LiF crystal and a neutron imaging plate (NIP) for 120 min in the JRR-3M thermal neutron radiography facility. The image in the LiF crystal was read out using a laser confocal microscope. All gaps were clearly observed in images for both the LiF crystal and the NIP. The experimental results showed that LiF crystals have excellent characteristics as neutron imaging detectors in areas such as high spatial resolution.     

Neutron spectra and angular distributions of concrete-moderated neutron calibration fields at JAERI

The Facility of Radiation Standards of Japan Atomic Energy Research Institute has been equipped with concrete-moderated neutron calibration fields as simulated workplace neutron fields. The fields use an 241Am-Be neutron source placed in the narrow space surrounded by concrete bricks, walls and floor. The neutron spectra and the neutron fluence rates of the fields were measured with the Bonner multi-sphere spectrometer system (BMS), spherical recoil-proton proportional counters, and a liquid scintillation counter (NE-213). The results were compared with each other. The reference values of H*(10) were determined from the results of BMS. The angular distributions of neutron fluence were calculated using MCNP-4B2 to obtain the reference values of Hp(10). The calculated results show that the scattered neutrons have a wide range of incident angles. The reference Hp(10) values considered the angular distribution were found to be 10-18% smaller than those without consideration.     

Measuring the thickness profiles of wafers to subnanometer resolution using Fabry-Perot interferometry

The resolution of an angle-scanning technique for measuring transparent optical wafers is analyzed, and it is shown both theoretically and experimentally that subnanometer resolution can be readily achieved. Data are acquired simultaneously over the whole area of the wafer, producing two-dimensional thickness variation maps in as little as 10 s. Repeatabilities of 0.07 nm have been demonstrated, and wafers of up to 100 mm diameter have been measured, with 1 mm or better spatial resolution. A technique for compensating wafer and system aberrations is incorporated and analyzed.