SVD Electronics Constraints DESY Meeting, 12-13 April 2012 SVD Electronics Constraints Markus Friedl (HEPHY Vienna)

Readout Chain Overview Analog APV25 readout is through copper cable to FADCs Junction box provides LV to front-end 1748 APV25 chips Front-end hybrids Rad-hard DC/DC converters Analog level translation, data sparsification and hit time reconstruction Unified Belle II DAQ system ~2m copper cable Junction box ~10m copper cable FADC+PROC Unified optical data link (>20m) Finesse Transmitter Board (FTB) COPPER M.Friedl (HEPHY Vienna): SVD Electronics Constraints 12-13 Apriil 2012

Constraints: Sensors L4…L6: sensors are ordered and in production Sensor design (size, strips, pitch) is thus frozen L3: tentative design in TDR, but not ordered yet Sensor design (size, strips, pitch, number of sensors) can be adapted Should be similar to TDR to achieve same (or better) performance Pitch adapter must be placed between sensor and hybrid minimum length given by line width/spacing requirements of manufacturing process M.Friedl (HEPHY Vienna): SVD Electronics Constraints 12-13 Apriil 2012

Constraints: APV25 Chips APV25 has fast shaping (50ns), thus noise figure strongly depends on capacitive load Must read out each sensor individually (no ganging possible) Achieved by Origami scheme, which allows double-sided readout at minimum material budget (0.55% X0 per layer) Implies one or more layers of Kapton with connectors in parallel to edge hybrids Stack of connectors needs mechanical strain relief Thus screwing like SVD2 is not possible for ladder mounting, because the Kapton flexes cover the hybrids M.Friedl (HEPHY Vienna): SVD Electronics Constraints 12-13 Apriil 2012

Constraints: APV25 Chips & Edge Hybrids Chip size = 8.055 (long) x 7.1 (wide) mm2 In fact, a margin for die cutting tolerance must be added Closest realistic APV25 “pitch” is 7.5 mm Defines the hybrid width (6 chips wide) In L4…L6, sensor is wider than 6 APV25 chips In L3, the sensor pitch is lower, thus 6 chips are wider than the sensor Potential problem due to space constraints Might try a 2-tier option (3+3 APV25 chips; experimental) to overcome this limitation M.Friedl (HEPHY Vienna): SVD Electronics Constraints 12-13 Apriil 2012

Constraints: Edge Hybrids Hybrid width given by 6 APV25 chips width Hybrid length given by pitch adapter gluing area APV25 chips including wire bonding Mechanical mounting holes on hybrid Line routing to back end Connector M.Friedl (HEPHY Vienna): SVD Electronics Constraints 12-13 Apriil 2012

Constraints: Hybrid Connector Connector must have Locking mechanism Halogen-free (no PVC) Gold plated contacts 50 pins Small feature size Nanonics (SVD2): expensive, fragile, two solder rows JAE: cheap, one solder row, but also larger Connector is practical, but not mandatory Could also solder wires directly if needed (option for L3) M.Friedl (HEPHY Vienna): SVD Electronics Constraints 12-13 Apriil 2012

Constraints: Cables 2 + 10 = 12m analog signal path directly driven by APV25 Connectors at Junction Box are inevitable (installation, power) Need same cable on both legs to guarantee same impedance Cable must have Twisted pairs (25 for 2m, 34 for 10m part) = no Kapton Low resistance to minimize power drop (OK with 30 AWG) Halogen-free (no PVC) Suitable cables: 0.635 mm pitch twisted flat IDC cable 30 AWG 3M 79992-25P-270A / 79992-34P-270A (CERN SCEM: 04.21.21.350.5 / 04.21.21.368.5) M.Friedl (HEPHY Vienna): SVD Electronics Constraints 12-13 Apriil 2012

Constraints: Cooling Each APV25 dissipates ~0.35w Heat must be removed from closed SVD volume Air flow is not sufficient (or storm blows off bond wires) No hard requirement for APV25 operating temperature But low temperature lowers noise figure Thus CO2 @ -20°C is our choice together with PXD (approximately +15% for S/N compared to room temperature) M.Friedl (HEPHY Vienna): SVD Electronics Constraints 12-13 Apriil 2012

Constraints: Position Accuracy Mechanical tolerances do not allow perfect positioning Gravitational sag of a ladder adds deviation dependent on position in f up to 100 µm according to simulation Can only be reduced at cost of material budget Perfect mechanical precision is not needed if we can do online alignment CMS experiment does it successfully with many more degrees of freedom Does not require 10 µm mechanical precision (anyway useless with 100 µm gravitational sag) M.Friedl (HEPHY Vienna): SVD Electronics Constraints 12-13 Apriil 2012