Latest news on dE/dx

1. Latest news on dE/dx P. Branchini, E. De Lucia, P. de Simone, L. Passalacqua and V. Patera

2. The available code ADC pedestals in HEPDB HEPDB bank DPED • Pedestal value in ADC counts • RMS value in ADC counts • Packed first layer-wire of the super-cell • Packed last layer-wire of the super-cell • Packed FEE address RAW2DQCE YBOS bank DQCE 1. Packed first layer-wire of the super-cell 2. Packed last layer-wire of the super-cell 3. Charge measurement in ADC counts

3. The AC module: DCDEDX for each reconstructed track: • steps along the helix to find the crossed wires, • evaluates the length inside the crossed super-cell, • associates the measured charge and writes the YBOS bank DEDX • the CPU time used is 25% of ATFMOD • the dimension of the DST output increases of 28% DEDX will be a real DST bank with the different particle hypotheses for each reconstructed track next step

4. YBOS bank DEDX • one bank for each reconstructed track • same ID of the DTFS bank of the corresponding track for each hit associated to the track : • Packed address of the ADC channel • Packed address of the crossed wires from DHRE2 • Packed address of the extrapolated crossed wires • Drift time of the IN wire • Drift time of the OUT wire • Collected charge in ADC counts • Track length • Effective track length

5. Fortran structure DEDX INTEGER MAXNADC PARAMETER(MAXNADC = 5000) TYPE DEDXStructure SEQUENCE INTEGER nADC INTEGER first_w(MAXNADC) INTEGER last_w(MAXNADC) INTEGER Layer(MAXNADC) INTEGER Wire1(MAXNADC) INTEGER Wire2(MAXNADC) INTEGER Wass1(MAXNADC) INTEGER Wass2(MAXNADC) REAL TrLen(MAXNADC) REAL EffLen(MAXNADC) REAL Time1(MAXNADC) REAL Time2(MAXNADC) REAL Charge(MAXNADC) END TYPE TYPE(DEDXStructure) DEDX In AC code the bank can be retrieved in a structure calling the function : DEDX_UPK(num_dtfs,DEDX_structure) A prod2ntu version has been produced to embed the new block of data

6. First look at the data • hits associated to reconstructed tracks • with tdrift ≤ 150 ns • have NO charge measurements • 30% of useful charge • measurements are lost • effect not present during first tests • on ADC boards • hardware check scheduled before • restarting phase

7. The integration gate is 1.8 ms  effective track length evaluation following equal time contours eff. length geometric length Red: effective charge collection area Blue: total charge collection area

8. Celle 3X3 Celle 2X2 Charge vs drift time distributions Q / effective track length Q / geometric track length

9. The dE/dx scenario kaons Bhabha scattering 3 body decays K, K0

10. Bethe-Block calibration Q/L vs log(bg ) using appropriate mass hypothesis in the various momentum ranges

11. electrons pions Resolution vs Number of samples to reach 5% @ N=50 of the prototypes we need to add another 5% effect !?! 0.5xN-0.5 7% (0.052 +0.052)1/2(50)1/2/N1/2 Stronger effect on the pions 0.4xN-0.33 tdrift < 800 ns

12. Raw s-t relations 800 ns • 1 mm spread The effect derives from the resolution on the effective track length A rough estimate of the uncertainty is 1 mm/3 cm  3%

13. requiring K decay vtx Nevertheless what can we do for 3 body decays at the present stage? (p < 150 MeV/c) mainly 3 charged pions Clear electron peak in the distribution

14. Using the probabilities of being electron, pion muon, clean samples of electrons and pions can be selected electrons requiring K decay vtx no K decay vtx pions muons

15. p (MeV/c) Clean electron sample requiring: no K decay vtx useful sample to study systematic effects associated to PID from time of flight for Ke3

16. Solutions under study to improve actual situation: • debugging of hardware settings as soon as we • restart • evaluation of the effective track length using • fine s-t relations

17. muons pions

18. How is the distribution of Nsamples affected by the cut on drift time? with the cut 150ns < tdrift < 800 ns without the cut Nsamples