1. November 4, 2004Carl Bromberg, FNAL LAr Exp. Workshop Nov. 4-6, 20041 Liquid argon as an active medium Carl Bromberg Michigan State University & Fermilab (2004) Better title What has been learned by ICARUS collaboration from ~20 years of drifting electrons in LAr

2. November 4, 2004Carl Bromberg, FNAL LAr Exp. Workshop Nov. 4-6, 20042 Sources Talk by F. Sergiampietri, at NuFact ‘01 (LANNDD) Talk by A. Para at Fermilab (Wine & Cheese) Publications –“Design, construction and tests of the ICARUS T600 detector”, NIM A527, 329 (2004) –“Study of electron recombination in liquid Argon with the ICARUS TPC” NIM A523, 275 (2004) –Measurement of the muon decay spectrum with the ICARUS T600 liquid Argon TPC”, Euro Phys J C33,2 (2004) 233 See list of ICARUS talks and papers on FLARE web site /www-off-axis/flare/documents.htm Particularly:

3. November 4, 2004Carl Bromberg, FNAL LAr Exp. Workshop Nov. 4-6, 20043 Liquid Argon basics W ion (1 MeV e – )23.6 eV Radiation Length19.55 g/cm 2 (14.0 cm) Density1.395 g/cm 3 (1 bar) Boiling Point87.2 K (1 bar) 89.3 K (1.25 bar) Nucl. Int. Length117 g/cm 3 Diffusion Coef.4.8 cm 2 /s Recombination factor0.64 (decreases ions/cm) dE/dx (min)2.1 MeV/cm e – in 3mm sample

4. November 4, 2004Carl Bromberg, FNAL LAr Exp. Workshop Nov. 4-6, 20044

5. November 4, 2004Carl Bromberg, FNAL LAr Exp. Workshop Nov. 4-6, 20045 TPC operation Time Projection –electrons drift toward transparent wire planes (minimum 1), and collection wire plane –planes with wires at various angles for stereo Ambiguities –track parallel to wire planes, all hits have same time, i.e., x. –track “dip” resolved by space points: vertices, delta rays or ionization bumps –distance between space points changes in the two views delta ray vertex

6. November 4, 2004Carl Bromberg, FNAL LAr Exp. Workshop Nov. 4-6, 20046 Signal characteristics Diffusion not a big factor in signal shape for d ~ 2 m Fit for x-position, resolution < 1 mm (2.5 MHz clock), helps with ambiguity resolution. Even with significant overlap in time, distinguish 1 track from 2, by consistent ionization/pulse width over many wires. But tracks in drift direction have very distorted pulse shapes FWHM ~ 4.5 mm  tracks = 16 mm 

7. November 4, 2004Carl Bromberg, FNAL LAr Exp. Workshop Nov. 4-6, 20047 Energy Resolution

8. November 4, 2004Carl Bromberg, FNAL LAr Exp. Workshop Nov. 4-6, 20048 FLARE is not ICARUS Typical ICARUS capacitance is 20 pF/m + 200 pF cable ~400 pF (max) induction wire Induction signals are smaller than collection signals by ~30% FLARE will have wires 4 times as long, noise will be 1.6 times larger, yielding S/N ~ 8 Does increasing wire spacing (to say 5 mm) help by lowering capacitance and increasing the signal? Cables for horizontal or stereo wires? Long cables mean more capacitance. Restrict to collection wires. Pixels anyone? K. McDonald.

9. November 4, 2004Carl Bromberg, FNAL LAr Exp. Workshop Nov. 4-6, 20049 For what is needed? Energy resolution of 2% great for EM shower. For total energy, make corrections based on particle ID via ionization changes, range,  ->  ->e decays, nuclear fragments & n-stars Full reconstruction is probably not needed. Automated scanning perhaps possible in 2D In scanning simulations, stereo views were not that useful. Helped in large angle particle ID, but not often in electron ID. Automatic space point finding is a challenge Cosmic Rays (during 1.3 ms readout). Should do simulation. Get ICARUS raw data? Interest by others trying to do surface calorimetry and tracking.