Emittance measurements using a finite slit-hole emittance meter

Summary form only given, as follows. A slit-hole emittance meter has been used to analyze the root-mean-square (RMS) emittance of a 2.5-MeV, 5-kA, 20-ns electron beam. The slits of the slit-hole emittance meter are made of 1.0-mm-thick, 5-mm-wide tantalum bars, separated by 0.5 mm. A radiachromic film detector is placed 10 mm downstream of the slits. The pinhole of an optical microdensitometer is used to measure the optical density of the film which is proportional to exposure to the electrons. The distribution function p(x, x´) can be obtained directly from this scan, assuming infinitely narrow slits. This distribution function can be used to calculate the RMS emittance of the electron beam. A major concern in the use of the distribution function derived in this way is that the slits have been assumed to be infinitely narrow when in fact in some cases they may be a substantial fraction of the width of the peaks on the scan. Recently, a formalism has been developed for dealing with finite slit widths in the slit-hole emittance meter. This formalism has been used to produce the actual distribution function from a finite slit-hole emittance meter