1. Perugia – IX SuperB General Meeting G. Finocchiaro INFN-LNF
DCH Summary
Perugia – IX SuperB General Meeting
G. Finocchiaro
INFN-LNF

2. G. Finocchiaro INFN-LNF
6/19/09
G. Finocchiaro INFN-LNF

3. G. Finocchiaro INFN-LNF
6/19/09
G. Finocchiaro INFN-LNF

4. G. Finocchiaro INFN-LNF
6/19/09
G. Finocchiaro INFN-LNF

5. G. Finocchiaro INFN-LNF
6/19/09
G. Finocchiaro INFN-LNF

6. G. Finocchiaro INFN-LNF
6/19/09
G. Finocchiaro INFN-LNF

7. G. Finocchiaro INFN-LNF
6/19/09
G. Finocchiaro INFN-LNF

8. G. Finocchiaro INFN-LNF
6/19/09
G. Finocchiaro INFN-LNF

9. G. Finocchiaro INFN-LNF
Summary of the conclusions
of the BABAR axial/stereo
committee at:
6/19/09
G. Finocchiaro INFN-LNF

10. G. Finocchiaro INFN-LNF
Actually, the BABAR field:sense ratio is 3:1
6/19/09
G. Finocchiaro INFN-LNF

11. Status report on CLUster COUnting activities
SuperB Workshop IX - Perugia
Status report on CLUster COUnting activities
G. F. Tassielli on behalf of CLUCOU group
INFN – Lecce
Dept. of Physics University of Salento
Dept. of Innovation Enginnering, University of Salento
G.F. Tassielli - SuperB Workshop IX - Perugia
16/06/2009

12. CLUster COUnting/Timing
MIN A386 (1997)
CLUster COUnting/Timing
dN/dx
dE/dx vs
<N>=0.98
<N>=1.01
single
sample
(3.7 cm)
100
samples
(3.7 m track)
Experimental distribution gives separation ≈ 3.2 or  = 3.7%
20% truncated mean (best)
gives separation ≈ 2 or  = 6%
Theory limit (according to parametrization):
Gaussian distribution (theory) gives separation ≈ 5 or  = 2.4%
gives separation ≈ 2.8 or  = 4.3%
G.F. Tassielli - SuperB Workshop IX - Perugia
16/06/2009 12

13. A CMOS VLSI chip for Cluster Counting readout
ADC characteristics
First 3.5 bit
gives the 3 plus significant bit of the output signal
Second 3 bit
gives the 3 less significant bit of the output signal
Overall architecture:
Only 21 comparators instead of 63
To improve linearity
Digital block to convert the output signal
form 6bit 1GHz to 12bit 500MHz
G.F. Tassielli - SuperB Workshop IX - Perugia
16/06/2009

14. Future plans the 2nd chip will be ready in the next two weeks;
build the evaluation board, (two weeks needed);
by July / September fully test of the chip;
Drift chamber prototype made of 3 set of drift cell layers, the external ones used to reconstruct the track and the central one to be instrumented with CluCou chip (spring 2010);
test the drift chamber prototype at Frascati BTF;
before the end of the year complete the detailed Montecarlo to:
before the end of the year complete the measures-studies on gas-wires gain.
have robust algorithm to count-timing the clusters;
test the impact parameter reconstruction algorithm;
study the particle identification ability.
G.F. Tassielli - SuperB Workshop IX - Perugia
16/06/2009

15. Report from setup @ LNF Perugia, DCH II 17 June 2009
Calcaterra, R. de Sangro,
G. Finocchiaro, M. Piccolo
INFN - LNF

16. Tracking telescope Two identical assemblies of 26 tubes each
Operated in LS mode
3 cm diameter, 100 μm wires
40%-60% Ar-iC4H10 mixture
Trigger is given by
coincidence of two
scintillators
Pack of 6 tubes in the
middle, to study
effect of quenching
17 June 2009
G. Finocchiaro

17. Time spectra
17 June 2009
G. Finocchiaro

18. Event Displays Require hits in top and bottom layer of each tracker
Perform track fit using approximate space-time relations (t=t0+Ar2+Br)
17 June 2009
G. Finocchiaro

19. Event Displays
17 June 2009
G. Finocchiaro

20. Event Displays
17 June 2009
G. Finocchiaro

21. Event Displays
17 June 2009
G. Finocchiaro

22. Space-time relations In middle layers (not used in the track fit)
17 June 2009
G. Finocchiaro

23. Track residuals
17 June 2009
G. Finocchiaro

24. G. Finocchiaro INFN-LNF
DCH End Plates
6/19/09
G. Finocchiaro INFN-LNF

25. Geometry of Forward DCH Endplate
Requirements for DCH endplates:
Sustain the ~3.5tons load of the wires with
O(mm) deformations
amount of material in front of outer detectors as small as reasonably achievable
particularly the forward endplate
Help keeping rates in the DCH as low as possible
6/19/09
G. Finocchiaro INFN-LNF

26. Options: material, shape
Carbon Fiber vs Aluminum
CF seriously considered for BABAR, but then discarded.
CF has X0~26cm vs. 8.9cm (Aluminum)
Flat vs. curved endplates
BABAR: 12mm/24mm Al (0.13 or 0.27X0)
with CF, max deformation of ~1mm with:
20mm flat endplates (0.08X0)
5mm spherical endplates (0.02X0)
KLOE proved that CF drift chambers with spherical endplates do work!
6/19/09
G. Finocchiaro INFN-LNF

27. Background and Tapered Endplates
To keep high rates in forward region under control, taper the endplates
Stairway option à la CLEO-c
Conical+spherical
Thickness O(4mm), or 1.5% X0 (perp. to walls) dmax=1mm
A lot of material!
6/19/09
G. Finocchiaro INFN-LNF

28. An alternative solution: mechanical quenching
Preventing electron multiplication in selected regions along the sense wire
Testing the idea: drift tubes, with part of the sense wire ‘screened’.
sense wire
“good physics track”
plastic collar
ionization in very forward region
80 mm inner Ø,
120 mm outer Ø
~10cm long peek tube
30 mm W (Au-plated) wire
17 June 2009
G. Finocchiaro

29. Mechanical Quenching
17 June 2009
G. Finocchiaro

30. Mechanical Quenching Collected charge vs. z along the wire 5 3 4 2 1
0 = Reference n.1
1 = PEEK #1 ~11cm
2 = PEEK # cm
3 = plastic # cm
4 = plastic #1 10.5cm
5 = Reference n. 2 5 3 4 2 1
17 June 2009
G. Finocchiaro

31. Mechanical Quenching
Preliminary results on mechanical quenching by wire screening are encouraging
Next steps:
measure time-to-distance relation with MIPs
evaluate efficiency and resolution as a function of z, particularly in the transition region
Need also to consider carefully:
Long-term behavior/aging
Stringing issues
17 June 2009
G. Finocchiaro

32. Inner + Outer Chamber?
The possibility of building two separate chambers has been suggested to address the problem of inner layers occupancy.
Preliminary analysis of the impact of inserting a CF wall of 0.3 or 1.0 mm thickness
(Arbitrarily) choose a radius of 41.5 cm: assume the two inner and outer chambers separated after the first three AUV super-layers of the BABAR layout
Benchmark channel: B⟶ππ
Look at DE and pT resolution
17 June 2009
G. Finocchiaro

33. Effect of a double wall: DE
Nominal
0.3mm
1.0 mm
17 June 2009
G. Finocchiaro

34. Effect of a double wall
Configuration
Sigma(DE)
Nominal
19.5±0.4MeV
0.3mm wall
21.6±0.1MeV
1.0 mm wall
25.1±0.1MeV
Configuration
Sigma(pT) ( GeV/c)
Sigma(pT) ( GeV/c)
Sigma(pT) ( GeV/c)
Nominal
8.3±0.1MeV
11.8±0.3MeV
13.7±0.3MeV
0.3 mm wall
9.8±0.2MeV
13.5±0.2MeV
15.4±0.3MeV
1.0 mm wall
12.8±0.2MeV
15.6±0.3MeV
17.0±0.4MeV
The solution with two separate chambers has significant impact on the DE, pT performances of the detector in B⟶ππ
17 June 2009
G. Finocchiaro

35. EndPlate Geometry - Summary
What we know already:
Carbon Fiber endplates with at least “moderate” shaping guarantee small deformations with significantly less material than Aluminum flat endplates
The Backward endplate must be reasonably flat to accommodate the FE electronics
We still need to choose among:
Spherical + conical
Spherical + staircase
Just spherical
with plastic tubes to quench wire amplification
convex endplates are a better match to the forward EMC (or PID detector) shape
6/18/09
G. Finocchiaro INFN-LNF

36. Summary on the remaining issues
Stereo+axial vs. stereo only
Optimize filling of active volume
need tracking and L1 trigger simulation study
Cell geometry
some consensus emerging towards square cells
DCH-SVT separation (a.k.a. DCH inner radius)
being addressed in the DGWG
better performances with reduced inner radius, but big concern for backgrounds
Optimization of gas mixture ongoing
Garfield studies
experimental LNF & UVic operational
goal is to complete by the end of 2009
Electronics
baseline is BABAR
cluster counting being considered
Background evaluation critical for many (if not all!) of the above issues
6/18/09
G. Finocchiaro INFN-LNF