210852321
MARK I MTA LINEAR ACCELERATOR RUN NO. 3
Experimental operation of Mark I from July 29 through Sept. 24, 1952 is reported. During the preceding two months shutdown, spark-damaged drift tubes No. 0, 1, and 2 were repaired and chemically cleaned. After a slow "bake-in" procedure, a cavity voltage of 20-Mv at 16% duty cycle was obtained. Although operation was not too steady, some preliminary beam evaluation tests were made. Proton acceleration threshold voltage was determined to be 18.5 Mv, based on the associated rapid increase in neutron flux beyond the D-8B target. The beam was found to be about 1 in. off from the cavity axis at the target. A pulsed beam current of 50 to 70 ma peak was reached. The results indicated that there was nothing to prevent a high-current pulsed beam from being produced. However, in spite of careful cleaning and slow bake-in methods, sparking in the 0-1 gap was still a problem. Since small scale tests indicated that Inconel had better resistance to spark damage than the deoxidized highphosphorous Cu originally used, Mark I was shut down to install Inconel overlays on the first two drift tubes. (For preceding report in series see LRL-71.) (auth)
108181646
ELECTRIC FIELD MEASUREMENTS IN THE MARK I ACCELERATOR BY THE GLO-BALL METHOD
118686248
Decay Constants of Charged Pseudoscalar Mesons
We review here the physics of purely leptonic decays of pi-, K-, D+, Ds+, and B- pseudoscalar mesons. The measured decay rates are related to the product of the relevant weak interaction based CKM matrix element of the constituent quarks and a strong interaction parameter related to the overlap of the quark and anti-quark wave-functions in the meson, called the decay constant fP. The interplay between theory and experiment is different for each particle. Theoretical predictions that are necessary in the B sector can be tested, for example, in the charm sector. One such measurement, that of fDs, differs from the most precise unquenched lattice calculation and may indicate the presence of new intermediate particles, or the theoretical prediction could be misleading. The lighter pi and K mesons provide stringent comparisons due to the accuracy of both the measurements and the theoretical predictions. This review was prepared for the Particle Data Group's 2008 edition.