PHENIX Vertex Detector with PHENIX Vertex Detector with Conventional Strip Sensors Conventional Strip Sensors

Abhay DeshpandeStony Brook University

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Conventional Strip Option (CSO)Conventional Strip Option (CSO)• Why consider this option?• Philosophy behind this development and the

strategy that has developed• Status

– Hardware: options available– Path forward:

• Prototype goals & tests• Module building options available• Studies of physics impact

• Possible impact on schedule & cost• Issues, concerns & decisions • Summary

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Why consider Conventional Strips?Why consider Conventional Strips?• Strip-Pixel design (one-sided, two dimensional read-out ) was

novel– Challenging… but possible– Realized by not only its proponents but also by the

reviewers… • All performance milestones for strip-pixel project reached,

although perhaps some what slower– Most recent: A full module with the ROC3-with stripixel

sensor has been produced, shown to operate well, despite the difficulties (Akiba & Nouicer’s presentations)

• We have seen the MIP peak!• Although all this has been possible, design and assembly

issues for the ROC3 as well as stripixel system performance issues remain a concern

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Why consider Conventional Strips?Why consider Conventional Strips?• It seems only prudent to step back and consider if

there are other options available as “back-up” which could be used if Stripixel Sensor does not work

• Conventional Strip Planning Task Force initiated – Alan Dion (chair) and 3 members– Charge: Develop a concrete plan of strip detector

using conventional sensors in the next few months

• Choice of sensor• Physics impact evaluation• ROC and Ladder configuration• Testing plan• Budget• Schedule

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Philosophy --> StrategyPhilosophy --> Strategy• Build up on the experience gained so far

– Use the developed parts of the project (ROCs)– Minimal R&D for cost and time saving

• Replace stripixel with available conventional strip sensor that matches closest to our present sensor in its physics requirements and dimensional needs

• Proceed to build modules using the ROC and the sensor

• Proceed with the same tests that were originally proposed in the stripixels

• Evaluate Signal/Noise and compare to VTX performance specs

• Evaluate the ability to produce strip layers with alternate sensor within project constraints

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RealizationRealization

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Possible RealizationPossible Realization• While “past performance is never a proof of future

results”, FNAL has shown that SVX4 + HPK off the shelf sensors have worked– We could try to be as close to this model as possible

• HPK has 3 x 6 cm strip sensors (80 m pitch) made for ATLAS, which could be used for initial tests – 2 sensors may be available immediately (free)– 5 more sensors may be available at minimal cost

• If ATLAS sensors work, we could ask HPK to produce slightly modified (size: 3 x 3 cm) sensors for our purpose

• Other options under investigation (SBU/D0)

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A possible realizationA possible realization

SVX

4

SVX

4

SVX

4

3 cm

Pitch adapter

hybrid

Sensor

3 cm

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Sensor moduleSensor module

Glue and wire-bondthe hybrid to the sensor

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RCC board, connectors, RCC flex RCC board, connectors, RCC flex cablescables

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4 sensor modules to read 2 views 4 sensor modules to read 2 views

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Final configuration on to the ladder…Final configuration on to the ladder…

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Building up confidence that we have Building up confidence that we have a viable fall-back plana viable fall-back plan

• Gain experience with conventional sensor• Single and Multiple hybrids, modules tested

independently and finally together on a ladder…

• These tests will be similar to those planned for the stripixel sensor

• Signal/Noise ratio compared with the stripixel sensors– Study with beam test

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Impact on PhysicsImpact on Physics

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Monte Carlo studiesMonte Carlo studies• Preliminary stand alone tracking studies initiated• Early results:

– Two layers with stereo angles are needed for high multiplicity collisions

– 900 stereo angle gives • slightly worse tracking efficiency but • better vertex resolution than the original strip-pixel

sensors (80 x 80 vs. 80 x 1000 )– Small(er) stereo angle gives worse efficiency

and no better vertex than strip-pixel sensors• If the “900 option” is chosen, it will have

consequence for the ROC design

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Tracking efficiency for Tracking efficiency for 2 Sensors crossed at 902 Sensors crossed at 90oo

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Momentum Resolution for Momentum Resolution for 2 sensors crossed at 902 sensors crossed at 90oo

Preliminary plan• Obtain existing sensors from HPK for tests with

ROC3• Develop layout of sensor+module• Hold technical review ~August 2008 (same for as

for stripixel)– Possible outcome: purchase of pre-production

sensors & ROCx design• Assemble conventional sensor+ROCx => Module• Assemble modules with non-ROC FEE + Stave =>

Ladder

Preliminary Schedule

WBS: About 2 months delay: Conservative (?)This is only the pre-production delayProduction: Delivery, QA, module construction: too early to estimate

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Preliminary cost guestimatePreliminary cost guestimate• Based on the known costs of 3x6cm sensors recently costed

for FVTX project in PHENIX– $600 including HPK R&D– For 3x3 unit the cost can be approximately $300

• We need 246 working modules with 4 sensors each 1000 sensors

• $300K + (contingency+ yield) ~ $500K

• These will become more firm as we communicate with HPK These will become more firm as we communicate with HPK specifically for this in near futurespecifically for this in near future

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Issues & ConcernsIssues & Concerns• Conventional Strip Sensor Option should work but

– Will ROC-on-Sensor design (proposed) work?– What (minimal) design modifications might be

needed?– What is the true impact to the project schedule?– What will be the total cost of going this way?

• All these need to be addressed and an informed decision needs to be made

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SummarySummary• While the strip-pixel design is going forward,

concerns related to large scale automated production have been raised based on the experience on building the first modules. This prompted us to look at alternative options using the conventional strip sensor in the project

• Early studies of feasibility, realization and physics impact for the CSO have started and look optimistic, but more are needed: – Prototyping, testing, physics impact– Cost & schedule impact

• Expect to finish most of the studies in the next few months after which through a technical review a decision could be made on the final design

• Until major concerns on the stripixel are alleviated the backup option will be pursued

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Schedule Impact Schedule Impact (preliminary estimate) (preliminary estimate)

• Sensor

• ROCx

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Schedule: Schedule: preliminarypreliminary Impact Impact estimate estimate

WBS: About 2 months delay: Conservative (?)This is only the pre-production delayProduction: Delivery, QA, module construction: too early to estimate