X-ray Detection Methods Research Articles

Experimental characterization of hot electron production under femtosecond laser plasma interaction at moderate intensities

We discuss methods and algorithms of high-temperature laser plasma electron diagnostics based on hard x-ray yield and ionic time-of-flight (TOF) spectra measurements in comparison with the results of direct electronic spectrum recording, with the help of the electrostatic spectrometer. The latter shows clearly the two-component nature of the electron population, arising at femtosecond laser plasma interaction. `Temperatures' of 200 eV and 6 keV for thermal and hot electronic components, correspondingly, were estimated from this measurement. We show that both ionic TOF measurements and double-channel hard x-ray detection allows the assessment of mean hot electron energy in a single laser shot. The former also provides for estimation of the thermal electron temperature and plasma charge state. Good coincidence between the data obtained from the three methods employed is demonstrated. We also describe how to apply our hard x-ray detection method to the case of relativistic laser plasma interaction, where single shot assessment may become even more essential.

New improved methods of X-ray detection

We present CCDs (CCD = charge-coupled device) as high performance X-ray detectors. These silicon pixel detectors (whose concept was invented in 1970) are mainly used today for detection of visible light with digital cameras. Generally, X-rays are detected by inserting a phosphorescent screen and collecting the light obtained onto the CCD. However X-rays can also be detected directly with excellent background rejection capabilities, good energy resolution and intrinsic pixel-size position resolution but with mediocre efficiency in a relatively small energy range and little or no timing information. For this application a slow, low noise electronics is needed. We will discuss how these detectors work, their advantages and disadvantages as well as future possibilities and limitations.

Towards slow ?? production via muon catalyzed fusion

Slow μ− production via dd-μCF using a two-layer arrangement is investigated. To determine its feasibility, experimental measurements are now in progress using the muonic X-ray detection method. The following experimental steps are being considered: (1) measurement of the number of μ− stopped inside a solid H2/D2 layer by detecting pμ Kα X-rays, (2) “hot” dμ emission detection by placing a secondary target at a distance of 10–30 mm from the layer and by detecting specific delayed X-rays, (3) measurement of the disappearance of dμ emission as the added D2 layer is increased, (4) dd-μCF measurement by detecting fusion protons, and (5) slow μ− emission detection. Results of the initial test experiment are presented.

Performance of the Charge-Coupled Device for Direct X-ray Detection in the Energy Range of 1-9 keV at the Synchrotron Radiation Facility

We performed a calibration of the charge-coupled device (CCD) in the direct X-ray detection method. The CCD chip is a product for optical use. The X-rays which we used are from the BL-7A in the Ultraviolet Synchrotron Orbit Radiation (UVSOR) facility, which gives us X-rays in the energy range between 1 and 9 keV. We report here the various characteristics of the CCD and its validity as an X-ray imager with a spatial resolution of pixel size (12×12 µm2) as well as an X-ray spectrometer at an energy resolution of about 240 eV (full width at half-maximum; FWHM) at the 5.9 keV X-ray. Our system functioned properly at a standard flux level in the UVSOR facility.

Methods for the Determination of Iodine-129

The detection methods for 129I now prevailing are based roughly on two different principles: one is the direct method such as the liquid scintillation method and X-ray detection method by use of the intrinsic Ge detector and the other is neutron activation method.The detection limit of the direct method is about 1dpm of 129I, while that of the neutron activation method, though it changes with the irradiation conditions, can reach the level of 10-4 to 10-6dpm.A lot of data have been reported by means of those methods on the environmental materials such as water, milk, soils, vegetation and thyroid of animals and human-beings.In this review, the level of 129I in the environment is briefly stated first, and then the individual detection methods and the pretreatments required for each measurement are referred.

Metals and x-ray emission spectrography

X-ray emission spectrography is currently enjoying a boom founded principally upon improved methods of X-ray detection. In a brief review, the main features of the method are sketched to show why it is of particular interest to metallurgists. Measurement of plating thickness, analysis of alloys, and point-to-point exploration of metallic specimens are described as typical metallurgical applications.