Performance of the low pressure MWPCs for f ission fragments under a high background

Two couples of low pressure multi-wire proportional chambers (MWPC) were located in the target chamber to detect fission fragments in a hypernuclei producing experiment at Thomas Jefferson National Laboratory (Jlab). In the experiment, a continuous wave (CW) electron beam was applied to form hypernuclei by electromagnetic interaction. In the target chamber, the high energy (1.853 GeV) and high intensity (500 nA) primary electron beam caused a high particle background, which influenced the detection of the fission fragments. This report described the design of the MWPCs and studied the fission-fragment detecting performance of them under such a high background. The efficiency of the MWPCs was given with the help of a high resolution kaon spectrometer. At the same time, the background particles were discussed with a Monte Carlo code based on GEANT4.     

Integrated evaluation of diffraction image quality in optical lithography using the rigorous diffraction solution for a slot

The method of integrated evaluation of quality of optical diffraction image is proposed. It uses several scalar parameters defined by integral comparison of two functions on the image surface. The first function represents real distribution of electric energy density on this surface, and can be simulated by the solution of corresponding exact or approximate diffraction problem of image formation. The second function describes required energy distribution on the given surface. The method is demonstrated by the example of evaluation of images formed by contactless printing from a mask in optical lithography, where the image function is computed by the known exact solution of plane wave diffraction by a slot in a conducting screen.