We review the various ways in which an electron beam can adversely affect an organic or inorganic sample during examination in an electron microscope. The effects considered are: heating, electrostatic charging, ionization damage (radiolysis), displacement damage, sputtering and hydrocarbon contamination. In each case, strategies to minimise the damage are identified. In the light of recent exp...

the magnetisation and electron spin resonance (esr) spectrum of two specimens of tetrahedral amorphous carbon (ta-c), deposited from a filtered cathodic arc, were measured over a wide temperature range. the magnetisation was found to consist of superparamagnetic, paramagnetic and diamagnetic contributions. the superparamagnetic contribution resembled that recently found in carbon prepared from ...

We present dose calculations to the basal cell layer of the epidermis resulting from skin contamination by radionuclides used in nuclear medicine. Dose calculations were made using the computer code VARSKIN, as modified by us to include these radionuclides and to account for their monoenergetic electron emissions. Results indicate that basal skin doses (taken to be at a depth of 0.007 cm) are a...

We report a new approach to the generation of high-current, high-brightness electron beams. Primary electrons are produced by a photocathode (or other means) and are accelerated to a few thousand electron-volts, then strike a specially prepared diamond window. The large Secondary Electron Yield (SEY) provides a multiplication of the number of electrons by about two orders of magnitude. The seco...

[1] The coupling of the Van Allen radiation belts to the Earth’s atmosphere through precipitating particles is an area of intense scientific interest. Currently, there are significant uncertainties surrounding the precipitating characteristics of medium energy electrons (>20 keV), and even more uncertainties for relativistic electrons. In this paper we examine roughly 10 years of measurements o...

Background: The aim of present study was to analyze the effectiveness of electron filters in the Telecobalt radiotherapy treatment by simulation technique.  Materials and Methods: The BEAMnrc Monte Carlo code was used to simulate the electron filters of thickness of 0.5 gm/cm2 below the trimmer bar for 35 × 35 cm2 field size in Theratron Equinox-80 telecobalt unit. The electron filters were mad...

We have measured electron impact ionization (EII) for Fe forming Fe from below the ionization threshold to 1200 eV. These measurements were carried out at the TSR heavy ion storage ring. The objective of using a storage ring is to store the ion beam initially so that metastable levels decay, thereby allowing for measurements on a well-defined ground-level ion beam. In this case, however, some m...

Background The Sediment Quality Objectives (SQO) indirect effects assessment determines whether sediments meet California’s narrative SQO for human health: Pollutants shall not be present in sediments at levels that will bioaccumulate in aquatic life to levels that are harmful to human health. This program determines whether sediment contamination at a site results in an unacceptable health ris...