Abstract:
The invention relates to an improved method for fabricating the amplification gap of an avalanche particle detector in which two parallel electrodes are spaced apart by dielectric spacer elements. A foil including a bulk layer made of dielectric material sandwiched by two mutually parallel metallic electrodes is provided, and holes are formed in one of the metallic layers by means of photolithography. The amplification gap is then formed in the bulk layer by means of carefully controlled etching of the bulk material through the holes formed in one of the metallic layers. The invention not only provides a simplified fabrication process, but also results in a detector with enhanced spatial and energy resolution.
Abstract:
An alternating electromagnetic field in the radiofrequency range is applied in a gaseous environment (4). Free electrons produced in the gas (4), by an ionising source of radiation (5) or by interaction of a charged particle beam with a specimen, are acted upon by the alternating electromagnetic field and undergo an oscillatory motion resulting in multiple collisions with the gas molecules or atoms. Amplified electron and photon signals are generated in a controlled discharge, proportional to the initial number of free electrons, and are collected by suitable means (6, 7, 8). The alternating field is generated either by electrodes (1, 2) biased with an alternating voltage, or by a coil driven by an AC current, and may be superposed with a static electric field. The detection device may be used with instruments such as electron microscopes, in ion beam technologies, and with instruments used for detection of ionising radiations such as proportional counters.
Abstract:
Disclosed is a proportional counter wherein nitrogen and hydrogen are contained in a gas (13) which is sealed in an envelope (12). By adding nitrogen, possibility of polymerization of the additional gas by radiation disappears, and a higher resolution is attained when compared with the cases where carbon dioxide is used as an additional gas. By adding hydrogen, gas gain variations are suppressed.
Abstract:
A method for correcting counting loss due to the energy discrimination is provided to reduce the counting loss due to noise by correcting the counting loss in a section classified as noise according to a threshold cut. A method for correcting a counting loss due to the energy discrimination includes the steps of obtaining a pulse height spectrum formula for ADC channel numbers by fitting level discrimination in a pulse height spectrum, obtaining a counting value of a Beta-ray source before a threshold value level by integrating the pulse height spectrum formula from a zero-energy point to values around the threshold value, and correcting a counting loss value by a rate of the counting after the threshold value level obtainable from the pulse height spectrum to the counting for a threshold cut.