Construction of Prototype B for the COMPASS-II Polarized Drell-Yan Experiment James Mallon of Abilene Christian University for the UIUC COMPASS Collaboration Abstract DEPARTMENT OF ENGINEERING AND PHYSICS While there has been significant progress in the past years of understanding the quark and gluon structure of the nucleon, many important questions remain open; in particular, we have only elementary understanding of the origin of the proton spin. The COMPASS project is a fixed-target nuclear physics experiment at CERN which explores the internal structure of the proton. COMPASS II’s polarized Drell-Yan measurements will be exploring the quark angular momentum contribution to the spin of the proton by studying quark-antiquark annihilation. Several drift chambers must be constructed to replace older, faulty straw chambers. Smaller prototype drift chambers were constructed, one in Saclay, France, and the other Prototype B (PTB), at the University of Illinois at Urbana-Champaign. PTB is 16.5” wide, 72” long, and 3.03” tall, with 66 wires across two separate wire planes. This poster will detail the methods used to fully assemble PTB. Future plans for the COMPASS II Collaboration are to construct the main body of Drift Chamber 5 at UIUC, with the anode and cathode planes being constructed during the summer of 2014 in at Old Dominion University in Virginia and CERN, respectively. The final construction and installation of Drift Chamber 5 is expected to happen at CERN in the summer of PTB Layout (2).75” thick aluminum endcaps, with aluminized mylar covering the hole and (2).188” thick aluminum spacers (2).157” thick G10 layers with a cathode plane covering the hole and (2).157” thick PCB and G10 layers with a cathode and wire plane covering the hole. One side of a wire plane: the high voltage pin is sticking up, and the soldered wires are behind it. Components The top two cathode layers are Kapton, and the bottom two are Mylar, allowing us to see which material is best for cathode planes. In making a cathode plane, first the Mylar or Kapton was stretched out, giving us even surface tension and eliminating droop. Next, a layer of graphite was sprayed on, to a thickness such that the resistivity of the area was about 10 kOhms. Epoxy was then applied to the G10 frame to which the cathode plane would be attached and then laid on the cathode. Cathode Production Wire Plane Construction In order to make sure that the wires stay at the same height throughout the length of the drift chamber, the wires are put under tension. To do this, we first soldered one end of the wire we were tensioning to the printed circuit board (PCB). We then attached a weight, by soldering and taping, either 1.5kg or 256g for the field and sense wires, respectively, to the unattached side of the wire. Next we would drape the weighted side of the wire across a pulley and solder the wire to the PCB. Next, we would cut the end of the wire off and finally trimmed it as close as possible to the solder puddle, to eliminate the chance of an electric field being produced at the tip of the wire, due to the tip being at high voltage. Drift Chamber 5 Acknowledgements Made possible in part by the ACU Nuclear Physics Research group, funded by the DOE, and the University of Illinois Nuclear research group, funded by the NSF. Future Plans DC 5 will be almost an extension of PTB: using the same concepts that we are testing in PTB. DC 5 will have 4 wire planes instead of the 2 found in PTB, named U, U’, V, and V’. The prime planes will be offset by 10°from their original plane, and U and V will be offset by 90°to each other.