1. Phone meeting, December 20, 2005P. Colas - Resolution in BOS Micromegas TPC1 Resolution from the 1mm pads of the Berkeley-Orsay-Saclay Micromegas TPC Reminder: the Berkeley-Orsay-Saclay cosmic setupReminder: the Berkeley-Orsay-Saclay cosmic setup resolutionresolution D. Burke 5, P. Colas 5, I. Giomataris 5, V. Lepeltier 4, M. Ronan 1, K. Sachs 2, T. Zerguerras 3 1) LBNL Berkeley, 2) Carleton Univ., 3) IPN Orsay, 4) LAL Orsay, 5) DAPNIA Saclay TPC MEETING

2. Phone meeting, December 20, 2005P. Colas - Resolution in BOS Micromegas TPC2 Cosmic-ray tracks Rows 5 & 6 (software from D. Karlen, adapted by M.Ronan)

3. Phone meeting, December 20, 2005P. Colas - Resolution in BOS Micromegas TPC3 2x10 mm 2 pads 1024 pads 1x10 mm 2 pads Readout anode pad plane Track reconstruction Subtract pedestals, using the first 15 time buckets + 15 after the chamber end Max-likelihood fit the distribution of the number of electrons per pad with 4 parameters : (x 0, ,1/R,  )  is the track width

4. Phone meeting, December 20, 2005P. Colas - Resolution in BOS Micromegas TPC4 Resolution Cross-check of the method: use only lines 1 and 2 and 9 and 10 to define , extrapolate hit 5 into row 6 using this , and make the distribution of the difference between extrapolation and position in row 6 divided by sqrt(2) Sigma of this distribution is the resolution. This gives the same result as using the track fitted using all rows except 5 and 6

5. Phone meeting, December 20, 2005P. Colas - Resolution in BOS Micromegas TPC5 Results on resolution

6. Phone meeting, December 20, 2005P. Colas - Resolution in BOS Micromegas TPC6 Results on resolution

7. Phone meeting, December 20, 2005P. Colas - Resolution in BOS Micromegas TPC7 Results on resolution

8. Phone meeting, December 20, 2005P. Colas - Resolution in BOS Micromegas TPC8 Residuals vs track position in the pad -> NO BIAS X track X pad -X track

9. Phone meeting, December 20, 2005P. Colas - Resolution in BOS Micromegas TPC9 Results on resolution at 1T Gas mixtureE drift (V/cm)  0 (  m) MC N eff MC Ar+5%iso22099±1591.4±5.040.8±6.442.1±2.5 P10140126±41124±920.0±8.522.7±2.5 Ar+3%CF 4 200225±26103.8±4.819±2058±17 Note: extrapolated to 4T, we expect a resolution of 144  at 2m with Ar isobutane and better than 120  on average, wherever the charge sharing holds

10. Phone meeting, December 20, 2005P. Colas - Resolution in BOS Micromegas TPC10 Conclusions Monte Carlo is now available for the diffusion and resolution studies. It shows a very good agreement with the data, except for ArCF 4 This shows that: - Mis-calibrations, noise, and all kind of experimental problems (the simulation assumes a perfect detector) have no effect on the resolution. - CF 4 behaves in a way different from expectation, though the drift velocity and track width are in very good agreement with MC -> one more piece in the CF 4 puzzle