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

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

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

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

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

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

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

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

G. Finocchiaro INFN-LNF Summary of the conclusions of the BABAR axial/stereo committee at: http://www.slac.stanford.edu/BFROOT/www/Detector/CentralTracker/mechanical/drift_system/procon.ps.gz 6/19/09 G. Finocchiaro INFN-LNF

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

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

CLUster COUnting/Timing MIN A386 (1997) 458-469 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

A CMOS VLSI chip for Cluster Counting readout ADC characteristics First sampling @ 3.5 bit gives the 3 plus significant bit of the output signal Second sampling @ 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

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

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

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

Time spectra 17 June 2009 G. Finocchiaro

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

Event Displays 17 June 2009 G. Finocchiaro

Event Displays 17 June 2009 G. Finocchiaro

Event Displays 17 June 2009 G. Finocchiaro

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

Track residuals 17 June 2009 G. Finocchiaro

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

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

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

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

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

Mechanical Quenching 17 June 2009 G. Finocchiaro

Mechanical Quenching Collected charge vs. z along the wire 5 3 4 2 1 0 = Reference n.1 1 = PEEK #1 ~11cm 2 = PEEK #2 12.5 cm 3 = plastic #2 16.5 cm 4 = plastic #1 10.5cm 5 = Reference n. 2 5 3 4 2 1 17 June 2009 G. Finocchiaro

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

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

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

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) (1.0-2.0GeV/c) Sigma(pT) (2.0-2.5GeV/c) Sigma(pT) (2.5-3.0GeV/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

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

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 setups @ 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