AGS Experiments

E802: My faculty mentor, Professor Shoji Nagamiya, came to Columbia in 1986 at the behest of Professor T.D. Lee to begin a new experimental program at Brookhaven National Laboratory studying nuclear collisions at the AGS (Alternating Gradient Synchrotron). Shoji, together with Brookhaven Physicist Chellis Chasman, proposed a survey experiment E802 for “Studies of Particle Production at Extreme Baryon Densities in Nuclear Collisions at the AGS“. The experiment used a single-arm magnetic spectrometer with excellent particle identification (Cerenkov and time-of-flight) detectors. This was a very successful program, laying the basis for many later developments in the field. Here is a link to the experiment’s demographics and publications

E859: It was clear that certain measurements in the E802 would require an upgrade, in particular, correlation measurements involving two charged kaons. These were very rare events, so detection required running at high intensities with second-level trigger that could perform particle identification in real time (a few tens of microseconds). I was co-spokesperson, along with Bob Ledoux (MIT) and Lou Remsberg (BNL), for a proposal to outfit the E802 apparatus with new trigger chambers and a second-level trigger. The E859 experiment’s title was “Studies of High Density Baryon Matter From Extended Measurements of Particle Momentum Distributions and From High Precision Two-particle Correlations“.

Designing, building and debugging the E859 Level-2 trigger was enormous fun. Lou Remsberg was the master architect, aided by Bob Ledoux, me, and an incredibly talented cadre of MIT nd Columbia students. We did this by “programming” a couple of bins of LeCroy ECL line look-up tables with an incredible rat’s nest of tiny twisted pair cables. We did get the damn thing to work, and the night when the event-display showed us event after event of two-kaon events tracked through the spectrometer was one of the most memorable in my professional career – well worth the many pre-dawn “meals” from on-site vending machines that preceded it!

The complete list of E859 publications is available here. Noteworthy results are the first measurement of the phi-meson properties in heavy ion collisions (the subject of my student Matt Moulson’s thesis) and the first correct treatment of Lorentz-frame effects of the “HBT effect” in the two-kaon system. My student Ole Vossnack made major contributions to this paper, while developing a beautiful analysis using finite-size Coulomb corrections in unlike particle pairs for his thesis. Unfortunately, this work was never published, because I was utterly failed at time management in balancing the demands of E859 publications and the development of experiments for RHIC.

E866: This experiment continued the upgrade process for the E802 spectrometer, preparing it for the higher multiplicities in Au+Au (as opposed to Si+Au) collisions and adding another magnetic spectrometer arm. 

E910: This was a dedicated proton-nucleus experiment based on a brilliant re-purposing of the EOS TPC  proposed by Brian Cole (who is now my co-Principal Investigator), producing many new results on strangeness production, constituent quark scaling and anti-proton production.