An electron beam microbunched on the optical wavelength scale of ø2.5 mm by an inverse free electron laser accelerator was observed. The optimum bunching was achieved for a 1% energy modulation of a 32 MeV electron beam with 0.5 GW CO2 laser power. The microbunching process was investigated by measuring the coherent transition radiation produced by the energy modulated electron beam. A quadrati...

The coordinate and energy distributions of the electron beam density at the Advanced Light Source have been obtained from measurements of the beam lifetime at various storage-ring apertures in the horizontal and vertical planes. It is shown that these distributions have a Gaussian core extended approximately up to five rms beam sizes. Beyond this point the electron density is defined by the ele...

BACKGROUND AND PURPOSE For several years three-dimensional treatment-planning systems have used pencil beam algorithms in the calculation of electron fields. Nowadays, exact Monte Carlo methods are commercially available, showing good correspondence to experimental results. Clinical examples are investigated to find differences in the dose distribution of treatment plans, which are calculated w...

A pulsed, 20 kv electron beam is focussed upon a vapor-deposited thermocouple, and the resulting temperature vs. time response is studied. The experimental data show much scatter, but are consistent with the theoretical prediction that the characteristic thermal response time T is proportional to d , where d is the beam diameter at the thermocouple. From these data, for the soft-glass substrate...

In convergent-beam electron diffraction (CBED) a highly convergent electron beam is focussed on to a small (~< 50 nm) area of the sample. Instead of the diffraction spots that are obtained in the back focal plane of the objective lens with parallel illumination in conventional selected-area electron diffraction, CBED produces discs of intensity. The point group can be determined uniquely from t...

background: exposure to ionizing radiation is known to induce oxidative stress followed by damage to critical biomolecules like lipids, proteins and dna through radiolysis of cellular water. since radiation has been widely used as an important tool in therapy of cancer, the detailed investigation regarding the dna damage and repair kinetics would help to predict the radiation sensitivity of cel...

We recently extended our experiments on z-dependent electron-beam microbunching using coherent transition radiation (CTR) into the high-gain, self-amplified spontaneous emission free-electron laser (FEL) regime. The UV-visible FEL at the Advanced Photon Source was operated at 530 nm and 385 nm using the bunchcompressed photocathode gun electron beam, linac, and 21.6 m of undulator length. The l...

OBJECTIVE Since the properties of polymers can be influenced using electron-beam irradiation, the aim of this study was to investigate whether electron-beam post-curing can improve the mechanical properties of experimental denture base polymers. MATERIAL AND METHODS Rectangular specimens of different experimental polymeric blends were electron-beam irradiated (post-cured) with 25 kGy and 200 ...