Reminiscences of Wit Busza and 41 years of p+A physics

• p+A (and d+A) experiments from Wit Busza’s pioneering 1972 experiment to the present are reviewed.
• Wit’s seminal result inspired the Wounded Nucleon and other extreme-independent models.
• Subsequent p(d)+A data from the AGS the CERN-ISR to RHIC revealed other fundamental elements.
• RHIC p−p, d+Au and Au+Au data establish constituent-quark-participants and rule out color-strings.

One of the more memorable (and easiest) proposal to deal with when I served on Bob Wilson’s Program Advisory Committee at NAL (Now Fermilab) from 1972 to 1975 was Proposal-178, “A study of the average multiplicity and multiplicity distributions in hadron–nucleus collisions at high energies”, with only 4 authors, Wit Busza, Jerry Friedman, Henry Kendall and Larry Rosenson, as presented at the PAC meeting by Wit. What I remember was that he discussed only ONE 5 inch photomultiplier with a Cherenkov radiator in the beam to make this measurement of production of charged particles with angles up to 30° in various nuclei, 40 h requested. This turned out to be a “seminal” experiment leading to the Wounded Nucleon and other participant models. Subsequent p(d)+A experiments from the AGS to RHIC, as well as alpha–alpha measurements at the CERN-ISR, will be discussed together with the various ‘participants’ that they revealed.