1. Time over Threshold (ToT) signal discrimination
A. Rotondi

2. The ATLAS experience NIM A 474(2001)172

3. ATLAS set-up For low energy X ray to be detected in the tube
Straw tube: 4 mm diameter, 30 mm Kapton, 70%Xe+20%CF4+10%CO2
drift time 40 ns very different from PANDA

4. ATLAS
DATA
SINGLE STRAW

5. ATLAS
DATA
32 tubes

6. ATLAS
simulations

7. Our simulations

8. Effective cluster/cm: nMIP dE/dx/(dE/dx)min
MIP particle:
Argon CO2
Cluster/cm
Prymary e
Effective cluster/cm: nMIP dE/dx/(dE/dx)min
N/n ~ 2.8

9. Straw tube performances: ADC charge
d electrons
taken into
account
keV
Electrons on the wire
no electronics response
electrons

10. Charge multiplication by each electron [from 90 to cutoff]
Gain: (GARFIELD) sampled
from the Polya distribution
time (s)

11. dE/dx performances, stt vs tpc
similar results with
1 bar pressure
Supposing
the particles
are hitting
22 tubes
tpc [Panda TPR]

12. The signal for each electron...
Average gain:
30000
Sampled from Polya
..... is summed-up for each primary electron.....

13. The formation of the signal ...
Primary electrons arrival times

14. SIGNAL TRESHOLD Fixed: above a static value
Constant fraction: a % of max of the signal
simulated white noise
time (ns)
Warning: this will lead to an offset

15. ns

16. pions

17. Pion/electrons
0.4 GeV
Pion/protons
0.4 GeV ns
Pion/kaons
0.4 GeV ns
Pion/protons
0.4 GeV
CF Discri
mination

18. Pion/electrons
1.0 GeV
Pion/protons
1.0 GeV
Pion/kaons
1.0 GeV

19. Conclusions No separation above 1 sigma
no correlation with PMAX signal values
no improvement from fixed threshold to
CF signal discrimination
new signal elaborations could be tested

20. THE END

22. Straw tube performances: response
Calibration: use a parallel beam and find the time response of the tube
(simulation of the calibration with cosmic rays ):

23. Fixed thresold
Constant fraction