SN0284 : Diffusion and drift studies of Ar-DME/CO2/CH4 gas mixtures for a radial TPC in the E perpendicular to B field
Updated on Sun, 2007-07-15 20:00 by testadmin. Originally created by chajecki on 2007-06-18 19:57.
| Author(s) | : | X. Bittl, V. Eckardt, H. Fessler, W.G. Gong, M. Konrad, A. Mock, P. Seyboth, J. Draper, M. Hildebrandt, B. Schmidt, K. Ness, A. |
| Date | : | Mar. 12, 1997 |
| File(s) | : | sn0284.ps.gz |
| Abstract | : | We have performed systematic studies of electron properties of diffusion and drift in three gas mixtures: Ar(50%)-DME(50%), Ar(50%)-CO2(50%), and Ar(90%)-CH4(10%) inside the {bf E} perp {bf B} field, with an aim to build a high-resolution radial Time-Projection-Chamber (TPC). Our TPC design is unconventional in that: (1) it drifts electron clusters in a radial electric field perpendicular to a magnetic field; (2) it employs microstrip gas chamber (MSGC) with pads for readout. To achieve the required spatial resolution and two-track resolution, we find that one must use a gas mixture based on cool gas such as CO2 or DME ((CH3)2O). Such a gas mixture has low diffusion coefficients and small Lorentz angle in the E perpendicular to B field. Its transport parameters are less sensitive to the B-field. Our measurements are compared with two transport calculations. For the Ar(90%)-CH4(10%) gas mixture, the calculations based upon the moment method agree well with our measurements, while the calculations using the Magboltz program largely over-predict our measurements for transverse diffusion and Lorentz angle. For the Ar(50%)-DME(50%) and Ar(50%)-CO2(50%) gas mixtures, which have slow drift and low diffusion, our measurements are consistent with calculations based upon either the moment method or the Magboltz program. |
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| Category | : | Technical |
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