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HFT, a High Resolution Vertex Detector for STAR

Wieman RNCLBNL

Thursday, May 17, 2006

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Topics

Requirements and features of the HFT

CMOS APS Detector Technology APS Introduction Basis for Technology Choice R&D plan, a 4 ms chip followed by a

0.2 ms chip Detector Verification in STAR

Environment DAQ readout approach Mechanical Concept

Minimum mass ladders Single end support

Stable reproducible spatial alignment Rapid insertion and removal

Thin beam pipe system Project Status Latest TAC Review

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Requirement

Topologically detect low momentum D’s in the environment of high multiplicity heavy ion collisions and high luminosity at RHIC in the most effective manner consistent with available resources

Special requirements prompts use of new technology

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Some HFT features

Pointing resolution (13 12GeV/pc) m

Layers Layer 1 at 1.5 cm radiusLayer 2 at 5 cm radius

Hit resolution 8.7 m

Position stability 10 m

Radiation thickness per layer

X/X0 = 0.28%

Beam pipe radiation thickness

X/X0 = 0.14%

Number of pixels 98 M

Raw data rate 31 GBytes/sec

Stored data rate after sparcification

90 MBytes/sec

Integration time (affects pileup)

R&D phase 4 msFinal detector 0.2 ms

Rapid installation and replacement

Reproducible positioning

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Basis for CMOS Technology Choice

CMOS APS technology Advantages:

Relatively RAD hard Available through multiple standard CMOS foundries Inexpensive commercial thinning Good success rate making working detectors by many institutions Excellent position resolution and fine granularity Partnered with the leading institution, IReS (now IPHC) in Strasburg Young technology, can expect considerable growth in capability

Disadvantages: Young technology for vertex detectors, currently no installed systems Limited signal to noise Current designs have relatively long integration times, i.e. potential

pileup at highest luminosities

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Si Pixel Developments in Strasbourg

Mimosa – 1 4k array of 20 m

pixels with thick epi layer

Mimosa – 4 Introduce Forward

Biased Diode Mimosa – 5

1M array of pixels, 17 m pixels using AMS 0.6 process

Used at LBNL for ladder development

Mimosa – 8 Fast parallel column

readout with internal data sparsification

MimoSTAR – 1 128x128 pixels using TSMC 0.25 MimoSTAR – 2 128x128 pixels using AMS 0.35

– Duct tape these to the STAR Beam Pipe for 07 run

MimoSTAR – 3 320x640 pixels using AMS 0.35 MimoSTAR – 4 640x640 pixels production run

Ultra – 1 Ultra – 2

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IReS MIMOSTAR chips

MIMOSTAR1 (0.25 m TSMC) Reduced size prototype but

sophisticated chip with complete functions for operation in a real detector system

Everything operating except pixel signal because of 0.25 m TSMC feature: Unexpected short signal decay time compared to theory and AMS experience.

MIMOSTAR2(0.35 m AMS optical process) Tested in beam 700-800 e most probable for Min-I 10-12 e-rms, noise. Signal decay time 100 ms

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Ultimate (fast APS detector) - good for high luminosity at RHIC

Submitted requirements list to IReS. In discussion

Technology MIMOSA8

Ladder active area 2cm 20cm

Pixel size 30m 30m

~Pixel mapping on the ladder 640 6400

Minimum operating distance from beam 1.5 cm

Power 100 mW/cm2

Operating temperature 30 C

Integration time[1] 0.2 ms

Mean silicon thickness 100m

Readout time 1 ms

Efficiency (min I)[2] 98%

Accidental cluster density 50/cm2

Binary readout, number of threshold bits[3]

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Radiation tolerance [4] 124 kRad

Number of conductors supporting the ladder (10 chips/ladder)[5]

140

Triggered readout, maximum trigger delay[6]

2 s

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Readout system – Triggered - Standard STAR Structure – using existing daughter boards

In Beam System test, two partial ladders with MIMOSTAR2 chips next run (focus of this year’s effort)

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Event size and data rate, data reduction crucial

Some numbers:

Itemnumber

bits/address 18

inner ladders 6

outer ladders 18

half chips per ladder 20

ave hits/half chip, inner, L = 1027 200

ave hits/half chip, outer, L = 1027 40

Only the hit addresses generate significant data volume. The totals are:

Itemnumber

Event Size 90 kBytes

Data Rate at 1 KHz event rate 90 Mbytes/sec

The HFT event size is significantly smaller than the TPC which has an event size of 2 MBytes for central Au+Au

Raw data rate: 31 GBytes/sec

Reduction 1/340,000

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Main R&D effort this year

Build two ladders with two MIMOSTAR2 chips each ( each chip 4 mm x 4 mm)

Install chip to chip (for coincidence) at an intersection region, preferably STAR

Operate with DAQ 1000 ALTERA/NIOS/SIU-RORC based system and STAR trigger interface

Gain operating experience and obtain track density numbers at small radius

Our engineers working closely with STAR DAQ expert, a benefit to us as well as helping STAR by expanding DAQ expertise

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Mechanical

Mechanical support Beam pipe

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HFT Mechanical requirements

Full self consistent spatial mapping prior to installation

Installation and removal does not disturb mapping

Rapid replacement

10 Micron stability

(mapping of BarBar with visual coordinate machine)

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Conceptual mechanical design

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Kinematic mounts

See: http://www.precisionballs.com/

Record position reproducibility 1 nm200 nm reasonable reproducibility expectation

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Cost and Schedule/Availability of Funds

The BNL Mid-Term Plan includes funding for the HFT Proposed HFT Profile

06 07 08 09 10 300K 1M 800K+300K 2.5M 2.5M R&D R&D R&D+Const Const Const

The proposed schedule of funds makes Mimosa-8 technology available in time to complete the project

The project has the 200 sec readout chip as the final goal The R&D profile allows us to complete the development of the MimoSTAR

chips and to readout data with a 4 msec frame rate Do extensive R&D and testing with MimoSTAR-4 chips Mount them in STAR Use the real beam pipe, real beam rates, real background Use the real mechanical insertion device

The Construction Profile allows us to complete the development of the Mimosa-8 style chips and readout with 200 sec frame rate

The final detector will be based on Ultra-XXX chips

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Project Labor Summaries

Engineering labor~ 13.5 FTEs

Technical labor~ 7.5 FTEs

Management & Management support~ 3 FTEs

Costed Labor Project ~3M

Contributed labor BNL ~1M LBL ~2M

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Project Status

Proposal submitted to STAR, waiting for go ahead BNL management has penciled in a budget and time line DOE is aware of plans for the HFT project

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Report of the Technical Advisory Committee for RHIC Detector Upgrades March 14-16, 2006 Committee members: M. Cooper (LANL), C. Haber (LBNL), B. Mecking (JLab), J. Proudfoot (ANL), V. Radeka (BNL), R. VanBerg (U. Penn, not present at the review), J. Va’vra (SLAC)

Heavy Flavor Tracker Physics Motivation The proposal to add a heavy-flavor tracker (HFT) to the STAR detector will significantly enhance the capabilities of STAR in the mid-rapidity range. The detection of a displaced secondary vertex will cleanly identify the production of heavy flavors from the topology of the event alone. For example, D-meson decays can be identified without the need for kaon identification and without combinatorial background.

Detector Concept and Technology The proposed APS technology is the most promising choice for high granularity, low radiation length, and low power dissipation vertex tracking in an environment such as RHIC. The proposed design configuration maximizes the solid angle coverage while keeping the number of detector layers and the area of silicon at a minimum. It is assumed that the small beam pipe diameter will be consistent with reliable machine operation.

The overall concept and implementation plan is well thought out.

This is a cutting edge technology, and it will be used for the first time on a fairly large scale in a large physics experiment. If successful, it will have a significant impact on future experiments.

Highlights from TAC review

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Cost, Schedule, Manpower • This is a well planned project which recognizes that it has limitations in the available manpower and funding, particularly with respect to mechanical engineering.

Recommendations 1. This R&D effort should proceed. The proposed schedule for realizing a working detector is very tight, and, as the STAR project manager noted at this review, the funding profile shown in BNL’s Mid-Term Plan for RHIC is not well matched to the current plan for R&D activities. BNL and STAR should work with DOE to make realistic plans for this valuable project.