Heavy Flavor Tracker Overview With parameters pertinent to the PXL Sensor and RDO design

L. Greiner 1PXL Sensor and RDO review – 06/23/2010

STAR

Heavy Flavor Tracker Overview

With parameters pertinent to the PXL Sensor and RDO design


STARPixel Sensor and Electronics Group

LBNLLeo Greiner, Howard Matis

Thorsten Stezelberger, Xiangming Sun, Michal Szelezniak, Chinh Vu,

Howard Wieman

UTAJo Schambach

IPHC StrasburgMarc Winter CMOS group


STARTalk Outline

• PXL in HFT - goals and parameters that provide bounds on the sensor and RDO requirements.

• PXL environment.• Sensor requirements based on goals and environment.• RDO requirements and design.• Development path for Sensors and RDO.• Summary.

The primarily focus of this talk is technical. Physics and simulations are outside of the scope of the review and discussed only to provide background for requirements.


STAR STAR Detector at RHIC


STAR Physics Goals

Direct Topological reconstruction of Charm

Detect charm decays with small c, including D0 K

Method: Resolve displaced vertices (100-150 microns)


STAR Inner Detector Region Upgrades

Graded resolution:TPC→SSD → IST → PXL~1mm ↘ ~300µm ↘ ~250µm ↘

<30µm

TPC – Time Projection Chamber (main detector in STAR)

HFT – Heavy Flavor Tracker SSD – Silicon Strip Detector IST – Inner Silicon Tracker PXL – Pixel Detector (PIXEL)

Tracking Inward


STAR PXL Detector

Ladder with 10 MAPS sensors (~ 2×2 cm each)

MAPSRDObuffers/drivers

4-layer kapton cable with aluminium traces

Mechanical support with kinematic mounts

Cabling and cooling infrastructure

Detector extraction at one end of the cone

New beryllium beam pipe (800 µm thick, r = 2 cm)

2 layers10 modules4 ladders/module


STAR Tracking Requirements

• -1 ≤ Eta ≤ 1, full Phi coverage (TPC coverage)• ≤ 30 µm DCA pointing resolution required • Two or more layers with a separation of > 5 cm.• Pixel size of ≤ 30 µm• Radiation length as low as possible but should be ≤ 0.5% / layer

(including support structure). The goal is 0.37% / layer• ~200-300 hits / sensor* (4 cm2) in the integration time window (at

operating point chosen).

* at r=2.5 cm

These tracking requirements and all following parameters have been established through simulation studies that have chosen an optimized operating point for the PXL detector through multi-parameter analysis of the entire upgrade system.


STAR PXL Tracking Environment

Charged particle density (at L = 8 x 1027 cm-2s-1) for a 200 µs integration time is:

• 63 hits / cm2 at r = 2.5 cm (includes peripheral collision electrons)

• 6 hits / cm2 at r = 8.0 cm

Radiation environment:• 20 to 90 kRad and • 2 * 1011 to 1012 1 MeV neq cm-2 year-1


STAR Mechanically Driven Constraints

• Detector physical geometry and segmentation.

• Sensor power dissipation (air cooling)

• Radiation length budget dedicated to cable/sensor assembly (0.17%)

• Number of sensors / ladder

Contributes to:

• Radiation load (r = 2.5 cm)• Fine twisted pair wire interface to ladders


STAR PXL Sensor RequirementsSensor requirements (consistent with IPHC development direction)

• ~2 cm x 2 cm (1 reticle) size.• Pixel size ≤ 30 µm.• Integration time of ≤ 200 µs for L = 8 x 1027 cm-2s-1

• Power dissipation ≤ 170 mW/cm2 (air cooling)• Binary output with remote threshold adjustment• Efficiency of ≥ 95% for MIPs with a simultaneous accidental noise

rate of ≤ 10-4

• Maintain efficiency and accidental rate after radiation exposure of 90 kRad and 1012 1 MeV neq / cm2.

• ≤ 4 LVDS output channels per sensor (ladder space)• Remote configuration


STAR PXL Attributes

Pointing resolution (12 19GeV/pc) mLayers Layer 1 at 2.5 cm radius

Layer 2 at 8 cm radiusPixel size 18.4 m X 18.4 m Hit resolution 8 mPosition stability 6 m rms (20 m envelope)Radiation length per layer X/X0 = 0.37%

Number of pixels 436 M

Integration time (affects pileup) 0.2 msRadiation requirement 20 to 90 kRad

2*1011 to 1012 1MeV n eq/cm2

Rapid detector replacement < 8 Hours


STAR RDO Infrastructure RequirementsIn addition to the detailed requirements imposed by the interface to the sensors, the RDO system shall:

• Triggered detector system fitting into existing STAR infrastructure (Trigger, DAQ, etc.)

• Deliver full frame events to STAR DAQ for event building at approximately the same rate as the TPC (1 kHz for DAQ1000).

• Have live time characteristics such that the Pixel detector is live whenever the TPC is live. (PXL adds ≤ 5% additional dead time)

• Reduce the total data rate of the detector to a manageable level (< TPC rate of ~1MB / event).

• Reliable, cost effective, etc.

Furthermore, this RDO system will be the basis of sensor testing including production probe testing so additional functionality will be included to enable this system to have the needed additional capabilities.


STARSensor generation and RDO attributes

Pixel

Sensors CDS

ADC Data

sparsification

readout

to DAQ

analogsignals

Complementary detector readout

MimoSTAR sensors 4 ms integration time

PXL final sensors (Ultimate) < 200 μs integration time

analog

digital digital signals

Disc.

CDS

Phase-1 sensors 640 μs integration time

Sensor and RDO Development Path

Develop sensor chips, 3 generation program (WBS 1.2.2.2)

1

2

3


STARSummary

• The detector parameters presented have been established through simulation studies that have chosen an optimized operating point for the PXL detector through multi-parameter analysis of the entire upgrade system.

• This is a set of detector parameters that, when used together, provide the required tracking resolution and efficiency in the required momentum ranges to do the physics to the required sensitivity and in the required time.

• We will use these parameters as the basis for the detector design. Deviations will be subject to simulation to determine the effect on performance.


STAR

backup


STAR Alternate Technologies Considered

• Hybrid– X0 large (1.2%)– Pixel Size large (50 m x 450 m)– Specialized manufacturing - not readily available

• CCDs– Limited radiation tolerance– Slow frame rate, pileup issues– Specialized manufacturing

• DEPFET– Specialized manufacturing– very aggressive unproven technology

MAPS sensors are the technology selected

Heavy Flavor Tracker Overview With parameters pertinent to the PXL Sensor and RDO design

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