The CDF Cherenkov luminosity monitor

We have built a novel device for precision measurements of luminosity in the CDF experiment at the high p(p) over bar collision rates expected during Run II. The detector consists of long, conical, gaseous Cherenkov counters that point to the collision region and monitor the average number of inelastic p(p) over bar interactions by measuring the number of particles, and their arrival time, in each bunch crossing. For these primary particles, using isobutane at atmospheric pressure as a radiator, a large amount of Cherenkov light (similar to 100 photoelectrons) will be collected, with good amplitude and time resolutions, onto small and efficient PMTs. Suitable amplitude thresholds will be applied to discriminate from non-primary particles and other backgrounds which yield little light in the counters. This detector is expected to reliably perform bunch-by-bunch luminosity measurements at peak instantaneous luminosities of 2 x 10(32) cm(-2) s(-1) with six interactions per bunch crossing, on average, and respond to a 132 ns bunch spacing. (C) 2001 Elsevier Science B.V. All rights reserved.