Neutron dosimetry at high energy accelerators

Several passive neutron dosemeters are described which can be used for measuring local dose equivalents behind the shielding of high energy accelerators. Their calibration constants are derived from measurements of the total neutron spectrum and are chosen so that the total neutron dose between 0.1 and 150 MeV is determined. Some of them are especially simple but can be used only if the type of neutron spectrum is known; others can be employed without additional information. Furthermore, active pulse counting dosemeters are described which are either modifications of known instruments or of novel design. They can be used to measure the total neutron dose equivalent or a known part of it in pulsed fields of any duty cycle. Results obtained by means of the described instruments and methods are compared in many neutron fields to demonstrate advantages and limitations and as a check of consistency

Instrumental neutrons activation analysis of Elbe river suspended particulate matter separated according to the settling velocities

SIGLEReprint from J. Radioanal. Nucl. Chem., Articles (1987) v. 114(1) p. 57-68 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Performance Measure as Feedback Variable in Image Processing

<p/> <p>This paper extends the view of image processing performance measure presenting the use of this measure as an actual value in a feedback structure. The idea behind is that the control loop, which is built in that way, drives the actual feedback value to a given set point. Since the performance measure depends explicitly on the application, the inclusion of feedback structures and choice of appropriate feedback variables are presented on example of optical character recognition in industrial application. Metrics for quantification of performance at different image processing levels are discussed. The issues that those metrics should address from both image processing and control point of view are considered. The performance measures of individual processing algorithms that form a character recognition system are determined with respect to the overall system performance.</p

Simultaneous operation of two soft x-ray free-electron lasers driven by one linear accelerator

Extreme-ultraviolet to x-ray free-electron lasers (FELs) in operation for scientific applications are up to now single-user facilities. While most FELs generate around 100 photon pulses per second, FLASH at DESY can deliver almost two orders of magnitude more pulses in this time span due to its superconducting accelerator technology. This makes the facility a prime candidate to realize the next step in FELs—dividing the electron pulse trains into several FEL lines and delivering photon pulses to several users at the same time. Hence, FLASH has been extended with a second undulator line and self-amplified spontaneous emission (SASE) is demonstrated in both FELs simultaneously. FLASH can now deliverMHzpulse trains to two user experiments in parallel with individually selected photon beam characteristics. First results of the capabilities of this extension are shown with emphasis on independent variation of wavelength, repetition rate, and photon pulse length