SN0408 : STAR TPC: Review of the Fields and Electron Drift in P10 in the Gating-Grid/Anode-Wire Region
Updated on Mon, 2007-06-18 19:57. Originally created by chajecki on 2007-06-18 19:57.
| Author(s) | : | R. Bossingham, I. Sakrejda, T. Trainor |
| Date | : | Sep. 3, 1999 |
| File(s) | : | sn0408.ps.gz |
| Abstract | : | The overall electron drift time from the STAR TPC cathode (central membrane) to one anode wire readout is regulated automatically; the HV system (Univ. of Washington) uses a feedback loop controlling the cathode potential. Electron drift velocities are nearly constant from cathode to gating grid, but vary from there to the anode wire. The velocities in the latter region differ slightly between the inner and outer subsectors, and the cathode-anode plane separation is also 0.2 cm more for the outer subsector. If, in contrast to the physical detection (anode-wire) planes at Z_(d,in) and Z_d,out, two "effective detection planes" are defined at Z'_(d,in) and Z'_(d,out)---conceptually independent of the channel-to-channel variations of FEE timing and overall trigger delay---the drift velocity can usually be treated as a constant. Z'_(d,out) and Z'_(d,in) are estimated using the Garfield drift code for this Note, then compared to experimental values. In this context, electric fields in the gating-grid/anode-wire regions of the STAR TPC are reviewed, comparing inner and outer subsectors. An understanding of these fields, along with the electron drift properties of P10, allows one to predict the sensitivity of Z'_(d,in) & Z'_(d,out) to various TPC parameters. |
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