1. April12 DST calibration status
Jochen Markert

2. Jochen Markert, Goethe Universität
Au+Au at 1.23 GeV/u (Apr12 )
AuAu 1.23 GeV/u
Facts:
557 hours beam Au on Au target
( ) x 106 ions per second
8 kHz trigger rate
200 Mbyte/s data rate
7.3 x 109 events
140 x 1012 Byte of data
DST Generations:
online : alignment and params online + old
gen0 : without prefit
gen1 : prefit procedure
dp 1.25 GeV
CC 2 GeV/u
pNb 3.5 GeV
pp 1.25 GeV CC 1 GeV/u
Ar+KCl
pp 3.5 GeV
Jochen Markert, Goethe Universität

3. Strangeness K0s K- L f NN excess energy 0.44 GeV only!
First measurement at such low beam energy
see Talks of:
Katharina
Manuel L f

4. RICH – MDC spatial correlations
Leptons
e- e+
RICH – MDC spatial correlations
see Talks of:
Patrick
Szymon
Jochen Markert, Goethe Universität

5. Global vertex reconstruction
First reconstructed during candidate search (no fit of drift times used)
Second reconstruction based on fitted inner MDC segments: filtering + LSM fit (including Tukey weights)
Third reconstruction based on fully reconstructed particles (same as segments)
Resolution along z ~1 mm (depending on multiplicity)
GSI target lab: B. Kindler et al., NIMP 655, 2011
Jochen Markert, Goethe Universität

6. Jochen Markert, Goethe Universität
START
Jochen Markert, Goethe Universität

7. Start detector calibration and T0 determination for Apr 12 DST
StartX and StartY calibrated, file-wise – data in Oracle
T0 determination based on three fastest particles in RPC/TOF from hit level
 ready, implemented (used in gen1)
cases:
0. StartX
1. StartY
2. Start X and Y
(mean)
HStart2Hit::getCorrFlag()
nucleus
Improvement: old method (first Start Hit taken) vs new approach (T0 selected based on TOF/RPC hits)
 method works correctly
BUT:
Works only if beam particles are separated in time more than 3 ns !!
S. Spataro

8. Start detector analysis – problem with T0
Limitations of the method based on TOF/RPC and Start:
Works only if beam particles are separated in time more than 3 ns !!
Still wrongly determined T0. Event selection: At least 5 protons in RPC with time larger than 1.5 ns (10-4 events)
Plots from P.Tlusty
We will mark such cases in StartHitFinder (more than 1 hit within 3ns window) by adding an additional flag: 3 or -2
Ultimate method should be based on fully reconstructed tracks (G. Kornakov)
Reconstructed T0 from all tracks in
single event compared to Start detector
Fit result based on 1/sqrt(N) contribution from
tracking and constant contribution from START.
σ(Start)=60ps
nucleus
To be implemented in HYDRA – high level analysis.
S. Spataro

9. Jochen Markert, Goethe Universität
MDC
Jochen Markert, Goethe Universität

10. Summer'2012 business: Autumn'2012 business:
Development and Implementation of New Ghost Rejection Method for the Cluster Finder Level 9 (class „hmdclookuptb“ in the Hydra2)
Autumn'2012 business:
New 36 „Butterfly“ cuts in 36 Θφ-regions
using real geometry,
corresponding magnetic field (0.72)
• Global Time Offset correction for
each MDC day by day
• Time Offset correction wire by wire
by special procedure
Olga Pechenova

11. Number of the ghost inner segments vs. Multiplicity (Simulation)
Nghost/Nall_segm
= 55.4%
Nghost/Nall_segm
= 8.0%
Nghost/Nall_segm
= 2.7%
Black cluster finder level 10 + old ghost removing (Level10)
Green cluster finder level 9 + old ghost removing (Level10)
Red cluster finder level 9 + new ghost removing (Level9)
Olga Pechenova

12. Comparison of the cluster finder
Level 9 (red) and Level 10 (black). Simulation
Efficiency vs.
multiplicity
Efficiency vs.
multiplicity
Clusters
Fitted segments
Efficiency vs.
momentum
Efficiency vs.
momentum
Clusters
Fitted segments
Olga Pechenova

13. The number of leptons, pions and protons
23%
17%
19%
21%
Gen1
New Cal1,
New Butterfly,
New Procedure
in Tracking
(Vladimir)
Leptons
Leptons
17%
3o%
Olga Pechenova

14. To do : Olga: tuning track finder and segment fitter parameters
for inner and outer segments (layer coefficients,
constant of uncertainty ~ 30 parameters) after all last changes
New Ghost Rejection for the 2nd track finder iteration
Tuning track parameters for the 2nd track finder iteration
CAL2 optimized versions (Claudia)
Mdc dE/dx calibration (Jochen)

15. Jochen Markert, Goethe Universität
RPC
Jochen Markert, Goethe Universität

16. RPC performance
The time resolution with the code as it is now in HYDRA is better than 88 ps** (88 ps is the resolution of pions with βγ=3, MIPS)
The correction of the position-time dependence still not implemented. This correction
improves resolution up to 72 ps for MIPs
pions.
Efficiency:
Pions over 94,6%
All particles over 97%
Possible improvements with information
from PCand
Double hit recovery method
Fine charge-time dependence correction (5-10 ps)
Fine position-time dependence correction (5-20 ps)
Resolution is not divided by 2
G.Kornakov

17. TOF

18. TOF Not fully calibrated in gen1 DSTs, work in progress.
charged hits multiplicity serving as LVL1 trigger:
velocity from vs charge*mom
TOF energy loss vs charge*mom:
TOF of selected of p-:
TOF-START resolution 209 ps
Not fully calibrated in gen1 DSTs, work in progress.
P.Tlusty

19. SHOWER

20. Shower gain calibration
Take charge distribution for one single pad:
Take global charge distribution integrated over all pads:
Calculate gain = max_global / max_pad
Maximum pos. from fit: max_pad
Maximum pos. from fit: max_global
S.Harabaz

21. After (gain calculated)
Before (gain = 1)
After (gain calculated)
Charge maximum position as a function of pad:
S.Harabaz

22. RICH,WALL RICH: pedestals calibrated WALL:
work on the charge calibration to be finished

23. Future Plans
Take advantage of all improvements since dst gen1 and run gen2 short after collab meeting. Do not wait for further tracking improvements or improved parameters (DST production takes ~1 week)
calibrate in parallel MDC dEdx, work on algorithms
schedule dst gen3 for February 2013
start working for efficiency parameters for simulations (our simulation is not tuned at all at the moment)

24. Thanks !

25. Backup

26. Real data Apr12 Difference in Mass Distribution: Level 9 – Level 10
RPC
Sector1 – black
Sector2 – red
Sector4 - green
Sector5 – blue
Sector6 - magenta
ToF
Real data
Apr12
Olga Pechenova

27. Autumn'2012 business: Cut good tracks – 0.26% Olga Pechenova
Global Time Offset correction for each MDC day by day
Time Offset correction wire by wire by iterative procedure
Now we have 3 tables MdcCalParRaw in Oracle:
Due to new Cal1 number of leptons increases up to 27%, pions - up to 16% !
New 36 „Butterfly“ cuts (36 Θφ-regions)
using real geometry, corresponding magnetic field (0.72)
Cut good tracks – 0.26%
Cut ghost tracks – 87.2%
Number of fully reconstructed tracks (in β vs
mom) ↑ by 1%, efficiency ↑ (especially in low momenta region)
II. New Procedure in Tracking (Vladimir)
Total: Improvements in number of tracks, chi2, number of wires/track, tracking efficiency, number of leptons (up to 51%), pions (up to 23%) !
Olga Pechenova

28. Finding of Target Segment
of the Event Vertex
Apply threshold to the distributions to filter
Find Target segment by best projection of all wires simultaneously
Smooth distributions to find maximum with best precision
After vertex fit all 12 target segments well separated