When energetic are incident on medium-to-high Atomic Number absorbers a substantial fraction are backscattered. This phenomenon is responsible for several undesirable effects in x-ray-tubes, in particular for a reduction in the x-ray output. The extend of this shortfall has been estimated by using Monte Carlo simulation by starting electrons at increasing depth inside the anode. The results indicate that output enhancements of nearly 50 percent could be achieved in principle if the electrons wasted in backscatter events could be trapped inside the anode. To test out this idea a further set of simulations were done by considering a novel anode geometry. Results showed that x-ray tube efficiencies might be substantially enhanced by this approach.

The fundamental study on a high-intensity flash water-window x-ray generator is describe. This flash x-ray generator was improved in order to increase the x-ray intensity and to produce high-intensity characteristic x-rays by forming the linear plasma x-ray source. The generator consists of a high-voltage power supply, a polarity-inversion ignitron pulse generator, an oil-diffusion pump, and a radiation tube with a capillary. High-voltage condenser of 0.2 (mu) F in the pulse generator is charged up to 20 kV by the power supply, and the electric charges in the condenser are discharged to the capillary in the tube after closing the ignitron. In the present work, the chamber is evacuated by the pump with a pressure of about 1 mPa, and the titanium anode and cathode electrodes are employed to produce L-series characteristic x-rays in the water-window range. The diameter and the length of the ferrite capillary are 2.0 and 30 mm, respectively, and both the cathode voltage and the discharge current displayed damped oscillations. The peak values of the voltage and current increased when the charging voltage was increased, and their maximum values were -11.2 kV and 4.4 kA, respectively. The pulse durations of the water- windows x-rays were nearly equivalent to those of the damped oscillations in the voltage and current, and their values were less than 15 microsecond(s) . In the spectrum measurement, we observed water-window x-rays.

Quasi-monochromatic x-ray production from the plasma flash x-ray generator having a cerium-target radiation tube is described. The K-series characteristic x-rays from the cerium target are very useful in order to perform angiography using iodine-based contrast medium because the photon energies of the x-rays are just over the K-absorption edge of iodine. The generator employs a high-voltage power supply, a low-impedance coaxial transmission line, a high- voltage condenser with a capacity of 200 nF, a turbo- molecular pump, thyristor pulse generator as a trigger device, and a flash x-ray tube. The high-voltage main condenser is charge dup to 60 kV by the power supply, and the electric charges in the condenser are discharged to the tube after triggering the cathode electrode. The flash x- rays are then produced. The x-ray tube is of a demountable triode that is connected to the turbo molecular pump with a pressure approximately 1 mPa. As the electron flows from the cathode electrode are roughly converged to the cerium target by the electric field in the tube, the plasma x-ray source, which consists of metal ions and electrons, forms by the target evaporating. Both the tube voltage and current displayed damped oscillations, and their peak values increased according to increases in the charging voltage. In the present work, the peak tube voltage was much higher than the initial charging voltage of the main condenser, and the peak current was about 25 kA with a charging voltage of 60kV. When the charging voltage was increased, the plasma x- ray source formed, and the characteristic x-ray intensities of K-series lines increased. In this experiment, we observed low-photon-energy bremsstrauhlung rays at the region of less than the K-absorption edge, because the tube current maximized at a low tube voltage.

Monochomatic beams of neutrons are obtained form a nuclear reactor polychromatic beam by the diffraction process, suing a single crystal energy selector. In Brazil, two nuclear research reactors, the swimming pool model IEA-R1 and the Argonaut type IEN-R1 have been used to carry out measurements with this technique. Neutron spectra have been measured using crystal spectrometers installed on the main beam lines of each reactor. The performance of conventional- artificial and natural selected crystals has been verified by the multipurpose neutron diffractometers installed at IEA-R1 and simple crystal spectrometer in operator at IEN- R1. A practical figure of merit formula was introduced to evaluate the performance and relative reflectivity of the selected planes of a single crystal. The total of 16 natural crystals were selected for use in the neutron monochromator, including a total of 24 families of planes. Twelve of these natural crystal types and respective best family of planes were measured directly with the multipurpose neutron diffractometers. The neutron spectrometer installed at IEN- R1 was used to confirm test results of the better specimens. The usually conventional-artificial crystal spacing distance range is limited to 3.4 angstrom. The interplane distance range has now been increased to approximately 10 angstrom by use of naturally occurring crystals. The neutron diffraction technique with conventional and natural crystals for energy selection and filtering can be utilized to obtain monochromatic sub and thermal neutrons with energies in the range of 0.001 to 10 eV. The thermal neutron is considered a good tool or probe for general applications in various fields, such as condensed matter, chemistry, biology, industrial applications and others.

Neutron generators based on the Radio Frequency Quadrupole accelerator are now used for a variety of applications. These compact linear accelerators can produce from 10⁸ to more than 10¹³ neutrons/second using either proton or deuteron beams to bombard beryllium targets. They exhibit long lifetimes at full output, as there is little target or beam degradation. Since they do not use radioactive materials, licensing requirements are less stringent than for isotopic sources or tritium sealed tube generators. The light weight and compact size of these robust systems make them transportable. The low divergence output beam from the RFQ also allows use of a remote target, which can reduce the seize of the shielding and moderator. The RFQ linac can be designed with a wide range of output beam energy and used with other targets such as lithium and deuterium to produce a neutron spectrum tailored to a specific application. These pulsed systems are well-suited for applications requiring a high peak neutron flux, including activation analysis of very short-lived reaction products. They can replace conventional sources in non-destructive testing applications such as thermal or fast neutron radiography, and can also be used for cancer therapy.

Neutron radiography is a well-known imaging technique among those working at nuclear research facilities. However, the move from laboratory to industry has been hampered by the generally large neutron flux requirements and by the relatively small number of nuclear research reactors. The development of imaging techniques that require lower total neutron exposure than traditional methods, coupled with improvements to non-reactor neutron sources suggest that broader application of neutron radiology may be imminent.

A neutron tomography system has been developed as nondestructive technique for quantitative assessment of impurity concentrations in metal castings. Neutrons maximize the sensitivity for certain isotrope while tomography provides the 3D density information. A specific application is the detection of hydrogen down to 200 ppm weight in aircraft engine compressor blades. A number of preprocessing corrections have been implemented for the projection images in order to achieve the detection requirements at a testing rate tree blades per hour. Among the procedures are corrections for neutron scattering and beam hardening in titanium alloy samples.

Neutron capture therapy (NCT) is a promising new binary therapeutic modality for the treatment of localized tumors. It is accomplished by injection and localization within the tumor of a neutron capture agent (NCA) that alone, is non- toxic. Whenthe tumor is then exposed to neutrons, a relatively non-toxic form of radiation, crytotoxic products are produced that directly or indirectly cause tumor cell death, and yet preserves normal surrounding tissue not contain the NCA. The UC Davis NCT program is currently working to develop and test new compounds or NCA in vitro and in vivo. Many groups worldwide are also working to develop the next generation NCA, but less than five facilities internationally are currently capable to treating clinical brain tumor patients by NCT and only two US facilities, MIT and Brookhaven National Laboratory. In addition to compound development, the UC Davis NCT program is preparing the UC Davis McClellan Nuclear Radiation Center's 2 megawatt TRIGA reactor for NCT clinical trials which would make it the only such facility on the West Coast.

The aim of this work was to investigate experimentally feasibility of realizing and prospects of real time fast neutron radiography with a portable neutron generator and a luminescent CCD-detector. Description of the used equipment and examples of radiographic images are presented. Perspective application of the equipment for visualizing light materials shielded by heavy ones in the field of non- destructive inspection was demonstrated. Feasibility to exploit x-rays emission of portable generators was revealed as well.

Reflection of cold neutrons from thin films, when the free neutron wave function is supposed to be the de Broglie singular wave-packet, is considered. Small corrections to interference pattern for the reflection dependence on the packet width is found. This correction for the case, when the width of the packet extracted from ultra cold neutrons anomaly, is calculated. The correction is shown can also be represented as a small contribution of incoherent reflection from interfaces of the film. The magnitude of this contribution is computed.

Two effects should be considered when keV photons suffer elastic scattering: the scattering of photons by the bound electrons of a free atom, named Rayleigh scattering and if, besides the Rayleigh scattering, the scattering due to different atoms gives rise to interference phenomena. The interatomic and intermolecular cooperative effects which modify the free-atom coherent scattering process are well know for highly ordered structures such as crystalline materials but are important for amorphous solids and liquids where short-range ordering occurs. Amorphous materials but are important for amorphous solids and liquids where short- range ordering occurs. Amorphous materials do not give such well-defined scatter conditions, but they do still give diffraction patterns which is characteristic of the particular materia. The availability of a very intense and highly collimated synchrotron radiation beam makes possible to study scattering properties of different amorphous materials. These materials were chosen because they intend to simulate the physical properties of body tissues and human bone. All measurements, were performed at the x-ray diffraction beamline of the Laboratorio Nacional de Luz Sincrotron, in Campinas, Brazil. The x-ray diffraction measurements were carried out with an 11.101 keV x-ray beam and included data from 1 equals 0.39 to q equals 4.13 per nm.

Adapting amorphous silicon imagers to the rigors of nondestructive evaluation has required the creation of new tools and techniques for successful detection of flaws in dense objects. At Los Alamos National Laboratory, extensive use of digital imagers and a desire to replace film with digital systems has led to additional research into modeling and simulation with an ultimate goal of improved techniques for using these imagers. The imagers have been used with varying success at x-ray energies ranging from 70 eV to 20 MeV, as well as with a variety of neutron energies at the Los Alamos Neutron Science Center. To simulate these diverse situations, a new version of the Monte Carlo Neutron/Photon Science Center. TO simulate these diverse situations, a new version of the Monte Carlo Neutron/Photon simulation package, developed at Los Alamos, is employed. The rapid simulation of various setups allows the rapid development of techniques without extensive and costly experimentation or test blocks. The simulations cover digital radiography as well as computed tomography. The results of these simulations leads to several techniques for digital radiology and computed tomography unique to amorphous silicon imagers, and provides additional information concerning advantage of amorphous silicon detector to provide density resolution in ways not possible with film. Also, the viability of amorphous silicon detectors at extremely high energies is simulated and tested experimentally.

Using exact results previously obtained we investigate the spreading of a propagating pulse due to higher order dispersion. An explicit example is considered where the spread and associated quantities are calculated exactly. We also discuss the effects of higher order dispersion on the contraction of pulses. We show that the average frequency of the initial pulse plays a much more important role when higher order terms are included.

The luminescence dampness of PbWO₄ crystals upon their excitation by H⁺ ion beam during prolonged time intervals was studied. An exponential law for the luminescence yield reduction at a density of the beam proton irradiation of j approximately equals 6 X 10¹² ion/cm² was registered, with the yield falling to a final value of J_(infinity ) approximately equals 1/3 X J₀. Similar kind modification of the luminescence yield suggests that some channels of the radiative relaxation process for intermediate excited states in the PbWO₄ bandgap could be clocked in part by local high energy excitation produced by energetic protons in the unit cells of lead tungstate.

The primary method used to determine if an unattended package is dangerous is currently transmission radiography. This system has two main drawbacks. First, the film must be placed on one side of the package and an x-ray source on the other side of the package. An arrangement that cannot always be achieved due to the position of the package. The other drawback is that the package may detonate before the film is removed and all the information about the package lost.

There has been much work increasing the sensitivity of detecting metallic objects in soils and other environments. This has lead to a problem in discriminating unexploded ordnance (UXO) and landmines form other metallic clutter. PELAN is a small portable system for the detection of explosives. PELAN weights less than 45 kg and is man portable. It is based on the principle that explosives and other contraband contain various chemical elements such as H, C, N, O, etc. in quantities and ratios that differentiate them from other innocuous substances. The pulsed neutrons are produced with a 14 MeV neutron generator. Separate gamma-ray spectra form fast neutron, thermal neutron and activation reactions are accumulated and analyzed to determine elemental content. The data analysis is performed in an automatic manner and a result of whether a threat is present is returned to the operator. PELAN has successfully undergone field demonstrations for explosive detection. In this paper, we will discuss the application of PELAN to the problem of differentiating threats from metallic clutter.

X-ray lateral migration radiography generate images of land mines and other objects buried with less than 10 cm of overlaying soil. An x-ray pencil beam illuminates the object area pixel-by-pixel, and a detector array of two collimated and two collimated, large area, scintillators respectively register once-scattered and multiple-scattered photons from mines, other buried objects, and the soil background. Two surface-feature-dominant uncollimated detector images and two subsurface-feature-dominant collimated detector images are typically generated. In the collimated detector images, a shifting of the images from the object center is proportional to the depth-of-burial of the detected object. Real mine test have been conducted and the images show the included air volume as a prominent feature. The combination of the geometrically regular air volumes and mine case present unique features which distinguish mine from nonmine objects. In fact, identification of some land mine types can be achieved from the acquired images. A field-test version of the system, to be used as a landmine object confirmation/identification detector is under construction. The completed generator/collimator x-ray source has been employed to produce the system-design raster direction of the incident photon beam, while 1D movement of the object is temporarily employed to simulate the orthogonal image axis. Easily recognized acquired images of the test object clearly indicate that the desired pixel dwell time of 0.01 sec has been achieved. This image acquisition speed translates into approximate values of 1.8 sec for a 20 by 20 cm interrogated area, consistent with scanning an antipersonnel mine, and 16 sec for a 60 by 60 cm area, consistent with an antitank mine.

IN the past few years, there has been an increasing need for new methods to detect and identify suspect materials in packages and containers used for transport and shipment of goods. Nuclear techniques are playing an important role in the design of such instruments and in this paper we discuss several new applications. While the methods for detecting nuclear radiation have become quite well established over the past few decades, it is interesting to see how some of the properties of these classical sensor are being improved and modified with new technology. In this short review, we review several novel applications for nuclear sensors and measurement techniques that are used in new security instrumentation designs.

A new intermediate energy x-ray source is described which uses a cw electron linear accelerator created specifically for this application. This source has been installed in the hub of a hollow-spoked rotation wheel to form a scanning beam of x-rays. As cargo is transported through the inspection tunnel at speeds up to 6 inches per second it is raster-scanned by this beam to form digital images of the backscattered as well as the transmitted x-rays. The system will be described in detail, and sample images of a heavily loaded 8 foot wide ISO container will be presented. Environmental radiation due to the x-rays scattered from the cargo itself will be discussed in the context of the tradeoffs between penetration, spatial resolution, x-ray energy, and x-ray flux.

A cadmium-zinc-telluride (CZT) detector has been developed for a bone densitometer that uses dual-energy x-ray absorptiometry (DEXA) to determine bone mineral density in vivo. A linear array of 16 discrete CZT detectors is used with a narrow fan-shaped x-ray beam to scan the patient. Each detector is 3 mm thick and 7 mm by 3 mm in area and has simple planar contacts. The x-ray beam has two broad energy lobes with effective energies of approximately 38 keV and approximately 65 keV. The energy sensitivity of the CZT detectors allows discrimination between low and high energy x-rays. Using DEXA, the relative difference in these two count rates permits a quantitative measurement of the real densities of bone mineral and soft tissue. The detectors demonstrate good performance characteristics and stable operation in a clinical environment. This paper discusses the suitability of CZT for use in DEXA applications and describes its successful implementation and performance in this bone densitometer.

Measurements of polycrystalline HgI₂ films on active matrix direct detection image sensors are described, for possible application to high sensitivity room temperature x- ray detection. The arrays exhibit low leakage current and very high sensitivity - roughly an order of magnitude better than has been demonstrated with other designs. The uniformity of the response varies randomly from pixel to pixel, for reasons that are not yet understood, but are probably related to the large grain size.

For the first time polycrystalline HgI₂ photoconductor material directly evaporated on a-Si array for direct conversion of x-rays for imaging purposes, were successfully imaged at Xerox-Palo Alto Research Center. The initial results are very promising and show a high x-ray sensitivity and low leakage current. Since Ti-W alloys are used as pixel electrodes, an intermediate passivation layer must be used to prevent a chemical reaction with the detector plate. The thickness that these Polycrystalline HgI₂ thick film detectors have been fabricated until now is up to 1,800 micrometers , which makes them useful also for high energy applications. The characterization of the Polycrystalline HgI₂ thick films deposited with or without the passivation layers by measuring their dark currents, sensitivity to 65 and 85 kVp x-rays and residual signals after 1 minute of biasing, will be shown for several detectors. Some preliminary results will be shown for some novel screen-printed HgI₂ detectors.

This paper discusses display parameters such as display function, contrast, dynamic range and spatial resolution of displays useful in digital radiology. It concentrates on the Cathode Ray Tube (CRT) as the maturest electronic display available at this tie. It appears that current high- resolution monochrome CRT display systems can present all information in digital medical images without interaction by the reader when the images are display-specifically processed to compensate for the reduced CRT MTF.

We demonstrate for the first time the feasibility of Coherent Scatter Computed Tomography (CSCT) with a fan geometry primary beam. CSCT allows superior tissue characterization and diagnosis by reconstructing the structure function rather than the attenuation properties as in regular CT. To study the feasibility of CSCT, Monte-Carlo based simulations of scatter distributions of technical phantoms were carried out. The projection data were used as input fro a novel algebraic reconstruction technique which takes account of the details of the measurement geometry. First results are discussed showing the potential of CSCT. The influence of achievable angular collimation quality is investigated and an outlook on future work is given.

A new set-up for high-energy micro tomography using synchrotron radiation at beamline BW5, HASYLAB at DESY, is presented. Results demonstrating the high spatial resolution by performing attenuation-contrast microtomography in the photon-energy range of 60 to 150 keV are given. The feasibility for investigation of larger samples by applying scanning techniques is demonstrated.

As part of the development of dedicated scintillation cameras, we compared the performances of 2 dedicated cameras with a standard clinical camera. The dedicated cameras were based on Position Sensitive Photo multipliers (PSPMTs): first, a single PSPMT coupled to a 6 by 6 by 0.6 cm NaI(Tl) crystal and second, multiple-PSPMTs coupled to a matrix of 2 by 2 by 6 mm NaI(Tl) crystal with hexagonal hole collimator. Image resolution was measured with all cameras as a function of depth. The ability of the cameras to measure small superficial tumors was tested with a phantom consisting of 6 hot cylindrical tumors of height 3 mm and varying diameters against a warm background of 4,1 cm cylinders. Tumors were stepped through the background and imaged at each level, starting at the collimator face, using a tumor to background activity concentration ratio of 10:1 and adjusting the imaging time for each to compensate for decay. Images were made of an anthropomorphic human thorax phantom with simulated breast lesions and detectability between the multi-PSPMT camera and the clinical camera was compared. The improve performance of dedicated cameras in specific tasks suggests that these devices will have a role in scintimammography and assisting in O.R. procedures such as sentinel node dissection and other shallow depth of field applications.

A high resolution, hand-held scintillation camera has been designed and built for specific Nuclear Medicine applications. Primary intended applications are pre-surgical and intra-operative lymphoscintigraphy. The detector head is highly compact with a 1-inch by 1-inch physical field of view. A variety of easily interchangeable collimators including parallel hole, diverging hole, and pinhole allow several choices of image parameters including variable spatial resolution, sensitivity and field of view. The camera can be operated in imaging mode or as a probe in a non-imaging mode. Surgeons performing sentinel node surgeries have the option of using the device asa standard audio-guided counting probe or as an imaging device to improve surgical management. The 20 mm FOV camera has 1 mm intrinsic spatial resolution. System FWHM in air is 2.1 mm and 2.6 mm at 0 cm from a high-resolution parallel hole collimator, respectively. FWHM of 3.8 mm is measured 2 cm from a 3 mm pinhole. Pinhole sensitivity is 600 cps/MBq above a 125 cps/MBq background for a 1 cm lesion 1 cm below a water surface. Nodes are identified in images even when overall count rate is not above the background from a nearby injection site.

The coincidence timing resolution is a critical performance parameter to determine if direct gamma-ray detection by semiconductor detector material such as CdTe or CdZnTe may be suitable for use in positron emission tomography systems. We report experimental results of the coincidence timing resolution measured with a pair of 2 by 2 by 10 mm³ CdTe detectors irradiated by 511 keV gamma rays under conditions that allow good timing resolution and good energy resolution to be obtained simultaneously. The measured coincidence time resolutions ranged from 14 ns to 24 ns. We also found that the coincidence timing resolution was proportional to the signal rise time, and that both of these were proportional to the electron transit time.

We are developing a scanner for simultaneous acquisition of x-ray computed tomography (CT) and single photon emission tomography (SPECT) images of small animals such as mice and rats. The scanner uses a cone beam geometry for both the x- ray transmission and gamma emission projections by using an area x-ray detector and pinhole collimator, respectively. The CT and SPECT data set are overlaid to form a coregistered structural-functional 3D image. The CT system includes a single CCD-based x-ray detector and a microfocus x-ray source. The SPECT scanner utilizes tungsten pinhole collimators and arrays of CsI(Tl) scintillation detectors. We describe considerations and the early performance of a prototype scanner.

Iterative reconstruction (IR) algorithms can reduce artifacts caused by filtered backprojection (FBP) or convolution backprojection (CBP). Recently, the computational effects required for IR of positron emission tomography (PET) studies have been reduced to make it practically appealing. We have made an implementation of the improved maximum likelihood-expectation maximization (ML-EM) algorithm. The transition matrix was generated based on the geometry of the instrument. Phantoms of 6 line sources and 19 line sources were used to test our accelerated ML-EM algorithms against the FBP method. The singles were used to calculate the random coincidence rates by a well known formula and were compared to the randoms obtained by another geometric method. We also designed a new model using two line sources to determine the ratio of random events to true events. The artifacts near those line sources were eliminated with the ML-EM method. With decay correction, the RC events were uniformity distributed in whole field after 10 iterations. The ML-EM reconstructed images are superior to those obtained with FBP. The patterns of randoms provide insightful information for random correction, which the hardware correction by the delay window can not provide. This information is particularly valuable when the delay window correction is not available in the old fashion PET scanner.

X-ray fluorescence element micro tomography allows to determine the element specific inner structure of a sample with resolutions in the micron range. It has a wide range of applications in many disciplines and is ideally suited for investigating element distributions inside of biological bulk samples at a cellular level with minimal sample preparation. The high intensity hard x-ray microbeam required for this scanning technique is produced using parabolic compound refractive lenses at a third generation undulator source. The sample is scanned through the microbeam in both translation and rotation and the fluorescence radiation created in the sample is recorded by an energy dispersive detector. From this data, the element distribution on a virtual section through the sample is recovered by tomographic techniques. The excitation of the fluorescence by monochromatic x-rays yields a high signal to background ratio and a low detection limit. As an example, we have investigated the distribution of physiologically relevant ions on a virtual section through a freeze dried root of the mahogany plant. Absorption of the fluorescence radiation inside the sample has to be taken into account in tomographic reconstruction and ultimately limits the size of the sample that can be investigated. A self-consistent reconstruction technique not requiring the explicit knowledge of the absorption inside the sample has been developed. Further developments of the technique are discussed.

The present report contains result of VNIIAs works on the development of a hardware-methodical complex on the basis of a portable neutron generator for identification of toxic chemicals in hermetically sealed containers of a different type. The technical characteristics of a specialized neutron generator developed by VNIIA for an identification installation and single board high-resolution gamma- spectrometer SBS-60 developed by Green Star are presented. The report contains results of measuring different toxic chemical imitators that are presented as inelastic scattering and radiative capture gamma radiation spectra. The possibility of toxic chemical 'key' elements reliable detection and their identification on the basis of the developed algorithm is shown.

Radiation Monitoring Devices has carried out research to develop a monolithic array of multiplexed, high-gain avalanche photodiodes suitable for use in a spectroscopic radiation-imaging device. To dramatically reduce the electronics required to support a large array we have utilized a unique property of avalanche photodiodes, and the method in which they are produced, to develop a relatively simple readout scheme using row-column addressing. Results indicate that there is good charge sharing between diode contacts on the back of a photodiode, feedback and crosstalk are minimal between avalanche photodiodes connected to a common data line using the diode-contact approach, and that reducing the noise contribution of each separate avalanche photodiode to the common data lien remains a critical issue to be examined further.

A neutron producing lithium target for a novel, accelerator based cancer treatment requires the removal of up to 6kW of heat produced by 1-2mA beam of 2.3-3.0MeV protons. This paper presents the results form computer simulations which show that, using submerged jet cooling, a solid lithium target can be maintained up to 1.6mA, and a liquid target up to 2.6mA, assuming a 3.0MeV proton beam. The predictions from the simulations are verified through the use of an experimental heat transfer test-rig and the result form a number of metallurgical studies made to select a compatible substrate material for the lithium are reported.

Elastic and inelastic scattering cross-sections for low, medium and high Z atoms are measured in vacuum using an x- ray tube with a secondary targets as an excitation source. Monoenergetic K(alpha) radiation emitted from the secondary target is used to excite the sample. Monoenergetic radiation emitted from the secondary target is used to excite the sample. Monoenergetic radiation is also produced using two secondary targets coupled to an x-ray tube and the radiation from the second target of the system is used to excite the sample. Elastic and inelastic scattering of K(alpha) X-ray line energies of the secondary target by the sample are recorded with Hp Ge and Si(Li) detectors. Using this system the degree of monochromaticity of the secondary emission and the geometrical effects of the measuring system is estimated. The efficiency is large because the secondary target acts as a converter. Experimental results based on this system will be presented and compared with theoretical estimates. The importance of the dat and the potential use of the system for few applications in the field of medicine and archaeometry will also be presented.

Images of small plastic and food materials are obtained using a tomographic device based on image intensifier at optimum energy. The flux emitted by the x-ray tube is filtered using appropriate filters at the chosen optimum energy and reasonable monochromacy is achieved and the images are acceptably distinct.

Fast neutron radiography is an element sensitive non- destructive testing method with potential applications in industry and the detection of contraband and explosives. The physical processes that control image formation can be examined individually by a variety of analytical and experimental methods in order to determine their impact on contrast, resolution and detectability.