1. Final Results of Drift Cell Simulation and Parametrization1
Final Results of Drift Cell Simulation and Parametrization
A. Gresele and T. Rovelli
Bologna University & INFN
Cell Simulation Procedure
Method Used to Parametrize
Final Results
Conclusions
9/12/98
A. Gresele - CMS week

2. Simulated Tracks Granularity2
Simulated Tracks Granularity
1 mm between x = 0 cm and 2 cm;
5 degree between d = 0o and 45o (between d = -45o and 45o when Bw not 0)
0.03 T between Bd = 0 and 0.3 T
0.1 T between Bn = 0 and 1 T
0.03 T between Bw = 0
and 0.3 T Bn Bw  Bd
Only BnBw and BnBd
pairs to reduce the num-
ber of simulated tracks. x
sense wire
cathode
track
9/12/98
A. Gresele - CMS week

3. Method Used to Produce the Drift Times3
Method Used to Produce the Drift Times
Full simulation on ALPHA machines ;
Bologna Condor facility used ;
Four tracks for each x, , B considered .

For each track we assumed the drift time is given by :
50% one electron
40% two electrons
10% three electrons
9/12/98
A. Gresele - CMS week

4. Method Used to Parametrize the Drift Times4
Method Used to Parametrize the Drift Times
The drift lines are more complicated when there is a magnetic field component along the sense wire , Bw .
we used different methods for the parametrization with Bw and Bn.
9/12/98
A. Gresele - CMS week

5. 5
Drift Lines
when
Bw = 0.3 T
9/12/98
A. Gresele - CMS week

6. Drift Time Variations with the track angle when B = 06
Drift Time Variations with the track angle when B = 0
To study the dependence of the drift time on the track, we calculated the difference between the drift time with   0 o and  = 0 o .
This variation is given in function of the track angle for 3 points , x = 0.6cm, x= 1.1cm and x = 1.6cm.
xpos = 0.6 cm
xpos = 1.1 cm
xpos = 1.6 cm
9/12/98
A. Gresele - CMS week

7. Parametrization of Drift Times vs Bw7
Parametrization of Drift Times vs Bw
We performs the regressions on the data for each  , x and Bw with HPARAM
(in PAW).
This in order to find the best polinomial parametrization of the drift time.
9/12/98
A. Gresele - CMS week

8. 8
To study the quality of the fit we plot the difference between the parametrization
and the points.
These differences
are   6ns.
9/12/98
A. Gresele - CMS week

9. Parametrization of Drift Times when Bn  09
Parametrization of Drift Times when Bn  0
xpos = 1.7 cm
Bn = 1 T - Bn = 0 T
The time variation (t) due to Bn is essentially independent of the track angle up to 45o and is fitted with a constant (at fixed position).
9/12/98
A. Gresele - CMS week

10. Final Parametrization of Bn10
Final Parametrization of Bn
For each value of Bn the results of the fit were plotted as a function of the distance from the wire.
These points were then fitted with a straight line to obtain the final parametrization .
Bn=1.0T-Bn=0T
Bn=0.5T-Bn=0T
Bn=0.1T-Bn=0T
9/12/98
A. Gresele - CMS week

11. Parametrization of Drift Times when Bd  011
Parametrization of Drift Times when Bd  0
The same procedure was used for Bd.
The deviations are very small and no correction is required.
Bd=0.30T-Bd=0T
Bd=0.15T-Bd=0T
Bd=0.03T-Bd=0T
9/12/98
A. Gresele - CMS week

12. Using this method we obtain...12
Using this method we obtain...
total of:
19 functions to parametrize Bw
10 functions to take into account Bn
9/12/98
A. Gresele - CMS week

13. Checks on parametrization13
Checks on parametrization
To check this procedure we generated 50 tracks at 3 points in the cell (x=0.2/0.4/0.6cm) where the expected deviations are largest.The angles and the magnetic field components ( Bn-Bw and Bn-Bd) were chosen randomly.
The differences between the generated drift times and those computed with the parametrization procedure are ,for Bn-Bw, within  8ns and ,for Bn-Bd ,within 6ns .
9/12/98
A. Gresele - CMS week

14.  and Bd , Bn components are chosen randomly. Bw = 0 T Bn-Bd  0 T14
 and Bd , Bn
components are
chosen randomly.
Bw = 0 T
Bn-Bd  0 T
9/12/98
A. Gresele - CMS week

15.  and Bd , Bw components are chosen randomly Bd = 0 T Bn-Bw  0 T15
 and Bd , Bw
components are
chosen randomly
Bd = 0 T
Bn-Bw  0 T
9/12/98
A. Gresele - CMS week

16. -30o <  < +30o  t   5ns Bw = 0 T Bn-Bd  0 T 9/12/9816
-30o <  < +30o
 t   5ns
Bw = 0 T
Bn-Bd  0 T
9/12/98
A. Gresele - CMS week

17. -30o <   +30o  t   5ns Bd = 0 T Bn-Bw  0 T 9/12/9817
-30o <   +30o
 t   5ns
Bd = 0 T
Bn-Bw  0 T
9/12/98
A. Gresele - CMS week

18. 18
Conclusions
The parametrization procedure looks reasonable. In fact the differences between simulated and parametrized times are less than 8ns ( less than 5 ns if 30o   30o ) ;
This parametrization is going to be introduced into CMSIM.
9/12/98
A. Gresele - CMS week