Measuring the Position resolution of a COMPASS Drift Chamber Prototype Rojae Wright, Mathias Perdekamp, Ihnjea Choi, Alabama A&M university, University of Illinois in Urbana Champaign Introduction TheoryResults References Noise Shielding Configuration Drift chambers are wire chambers that are built to detect the passage of charged particles by means of ionization of gas atoms and molecules. Drift chambers generally feature a row of alternating sense and field wires between two cathode planes. Positive high voltage is supplied to the anode sense wires along with the cathode planes and the chamber is filled with a special gas. When a charged particle passes through a drift chamber it creates an electron ion pair. The applied high voltage creates an electric field and prevents these particles from recombining with its molecule or atom.This causes the freed negatively charged electrons to drift towards the anode sense wires and the positively charged ion to drifts towards the field wires and the cathode plane. Electrons drift at a constant velocity and by Knowing the initial and arrival time(ΔT) and by the formula ΔX= V × ΔT can be used to determine the location of the passage of a charged particle. Their drift velocity can be accurately computed and the use of high- resolution timing devices allows the position of the track to be calculated precisely from the drift time of the electrons. COMPASS is a fixed target experiment at CERN in Geneva, Switzerland which investigates the quark and gluon structure of proton. The experiment will study the transverse spin- and momentum dependent quark structure for the proton through pion-induced Drell-Yan scattering off transversely polarized proton targets. The observed Sivers asymmetries are thought to be indicative of quark orbital angular momentum inside the proton. UIUC is responsible for building and designing two drift chambers to replace aging straw chamber stations in the COMPASS spectrometer. UIUC has built two drift chamber prototypes. The current prototype B has 16 anode sense wires in each of two separate planes. Cosmic rays are used to measure the position resolution of the drift chamber. This poster describes the details on the experimental method and steps that will lead to the measurement of the position resolution for the COMPASS drift chamber prototype B. NSF Grant PHY <The Drell-Yan process is the creation of a lepton-antilepton pair from the decay of a photon produced in quark-antiquark annihilation. The drift chamber Prototype B in the UIUC clean room. <The diagram above shows the layers of the drift chamber. The distance between sense wires is 8 mm. TDC Distribution for 8 Channels 1. Terminated the input trigger(TTL) with 50 ohm 2. Shield analog part of FEE with cu tape 3. Shield FEE box with Cu sheet cosmic ray peak(signal) near -300 bin at each plot. 8 channels(FEE) connected to PTB Top layers (16 channels TDCs, w/o 50ohm termination This data taken with 3 noise- shielding configuratio ns TDCs, w/o 50ohm termination & shielding Same TDC plots with 2 noise- shielding configuration Same TDC plots with 2 noise- shielding configuration s Conclusion and Future Work By changing the shielding configurations, you can see the behavior of noise level which is the distribution near the peak area.Therefore,We saw clear cosmic ray signal from PTB and noise increased when the shielding removed.In the future we intend calculate the position resolution of PTB