BNL-Nuclear Physics Seminar Rachid Nouicer 1 Brookhaven National Laboratory Research Affiliate of...

BNL-Nuclear Physics Seminar Rachid Nouicer 1

Rachid NouicerBrookhaven National Laboratory

Research Affiliate of RIKEN-BNL Research Center

New Era of Heavy Flavor Measurements at RHIC:

Silicon Vertex Tracker (VTX) Construction and Performance Results From Run-11

BNL Nuclear Physics Seminar, November 29th, 2011

Run-11AuAu

200 GeV

VTX


Outline of the Talk

• Motivation: why heavy flavor physics is so appealing

• VTX technology choices and construction phases

• VTX commissioning with p+p at 500 GeV and

performance results Au+Au at 19.6, 200 and 27 GeV

• Reconstruction analysis results using VTX and central

spectrometers (DC, PC, RICH, EMCal...) in Run-11

- Primary vertex, beam size, DCA…

• Detector successes, challenges and lessons learned

• Summary


Motivation: why heavy flavor physics is so appealing

• The physics goal of HF is to identify and study the properties of QCD matter created in HIC

• HF hadrons carry quarks with large masses, and this provides particularly good probe of medium produced

- mc ~ 1.3 GeV, mb ~ 4.8 GeV >> Tc , ΛQCD less affected than light quarks

• HF quarks are produced early in the collisions (large Q2)

• They travel through the created medium interacting with its constituents

- Possibly a more direct connection to transport properties of the medium

- Radiative energy loss should play a dominant role

• Three ways to see open heavy flavor:• D- and B-mesons via hadronic decays (at mid-rapidity)• D- and B-mesons via single electrons (at mid-rapidity)

• D- and B-mesons via single muons (at forward rapidity )


One of the most surprising results from RHIC


R. Nouicer arXiv:0901.0910 [nucl-ex]

• Heavy flavor suppression is as large as for light quarks

• No dependence of energy loss on flavor

• Do we understand the energy loss mechanism?

• Where is Beauty contribution?


One of the most surprising results from RHIC

• Heavy flavor suppression is as large as for light quarks

• No dependence of energy loss on flavor

• Do we understand the energy loss mechanism?

• Where is Beauty contribution?


R. Nouicer arXiv:0901.0910 [nucl-ex]


Motivation: Theoretical Calculations for HF

To be published by Ralf F. Rapp et al.

Realistic hydro (fit to multistrange and bulk particles) with heavy-quark diffusion in the QGP, hadronization via resonance recombination/fragmentation, followed by hadronic diffusion. There is no tuning of the HQ physics.

• Ralf F. Rapp, private communication

Nuclear modification factorB+D-mesons via single electrons (NPE)

Elliptic flowB+D-mesons via single electrons (NPE)

Ralf F. Rapp Ralf F. Rapp


Motivation: Theoretical Predictions for HFNuclear modification factor

Elliptic Flow

• D- and B-mesons via single electrons (at mid-rapidity)


Ralf F. Rapp

Ralf F. Rapp

Ralf F. Rapp


Motivation: Theoretical Predictions for HF

D-mesons via hadronic decays B-mesons via hadronic decays


Ralf F. Rapp

Ralf F. Rapp

Ralf F. RappRalf F. Rapp


Pioneering High Energy Nuclear Interaction eXperiment

2 central spectrometers

2 forward spectrometers

3 global detectors- Luminosity Monitoring

(BBCN,BBCS)

- Centrality (BBC vs ZDC)

- Local polarimetery (ZDC & SMD)

West

South

North

East

Photon, hadron, electron||<0.35, =

detection 1.2<||<2.4, 2 in

PHENIX Detector: Present


Present PHENIX: Access signal from heavy quarks via single electron measurement

PHENIX: PRL 88, (2002) 192303

Precision of the measurement limited by systematic uncertainty because, Huge background contribution

0 and Dalitz decay

conversion ( -> e+e-) Cannot separate charm and beauty contributions independently Lifetime (c) of mesons

with charm and beauty• D± = 312 m, D0 = 123 m • B± = 501 m, B0 = 464 m

Secondary vertex identification isrequired to suppress background for non-photonic electrons, and will make it possible to distinguish if an electron originates from charm or beauty.

Heavy-Quark Probes at PHENIX


- Heavy flavor (c and b quarks) are produced in the early stages of heavy ion collision- Experimentally easy to observe Semi-leptonic decays

VTX

e-e+

Expected DCA resolution

~ 40 m Au+Au 200 GeV

pions in 3 <pT<4 GeV/c

Life time (c) D0 : 123 mm B0 : 464 mm

DCA

ppD

B

e

e

Barrel 1Barrel 2Barrel 3Barrel 4

Barrel 1Barrel 2Barrel 3Barrel 4

Pixel

Stripixel

Technology Choices: VTX Concept


VTX Layer R1 R2 R3 R4

Geometrical dimensions

R (cm) 2.5 5 10 14

Dz (cm) 21.8 21.8 31.8 38.2

Area (cm2) 280 560 1960 3400

Channel count Sensor sizeR z (cm2)

1.28 1.36(256 × 32 pixels)

3.43 × 6.36(384 × 2 strips)

Channel size 50 425 mm2 80 mm 3 cm(effective 80 1000

mm2)

Sensors/ladder 4 4 5 6

Ladders 10 20 18 26

Sensors 160 320 90 156

Readout chips 160 320 1080 1872

Readout channels 1,310,720 2,621,440 138,240 239,616

Radiation length(X/X0)

Sensor 0.22% 0.67 %

Readout 0.16% 0.64 %

Bus 0.28%

Ladder & cooling 0.78% 0.78 %

Total 1.44% 2.1 %

Pixel Stripixel

Layer radius Detector Occupancy in Central Au+Au collision

Layer 1 2.5 cm Pixel 0.53 %

Layer 2 5.0 cm Pixel 0.16%

Layer 3 10.0 cm Strip 4.5 % (x-strip) 4.7 % (u-strip)

Layer 4 14.0 cm Strip 2.5 % (x-strip) 2.7 % (u-strip)

Technology Choices: Barrel VTX Parameters

plane

Pixel

Stripixel


Technology Choices: Silicon Pixel Barrels 1 & 2ALICE1LHCb readout chip:

Pixel: 50 µm () x 425 µm (Z). Channels: 256 x 32.Output: binary, read-out in 25.6 [email protected] Hardness: ~ 30 Mrad

Sensor module:

4 ALICE1LHCb readout chips.Bump-bonded (VTT) to silicon sensor.Thickness: 200 mThickness: r/o chips 150 µm

Half-ladder (2 sensor modules + bus)

1.36 cm x 10.9 cm.Thickness bus: < 240 µm.

SPIRO module Control/read-out a half ladderSend the data to FEM

FEM (interface to PHENIX DAQ)Read/control two SPIROsInterface to PHENIX DAQ

Active arear

1.28 cm = 50mm x 256z

1.36 cm = 425mm x 32

Solder bump

~20m


• Sensor module consists of 4 ALICE Pixel readout chips bump-bonded to silicon sensor

Sensor

• Half stave is mounted on the support structure

Thermo plate + cooling

• Pixel BUS to bring data out and send controlsignal into the readout chip is mounted on thehalf stave

• Each detector module is built of two halfstaves, read out on the barrel ends

Half stavePixel BUS

Data

• One readout unit, half stave, made from two sensor modules

Full stave

22cm

1.4cm

ALICE LHCB1 chip

SensorSensor Module

Bus

Glue

GlueStave

Readout chip

Sensor

Technology Choices: Silicon Pixel Barrels 1 & 2


Status: Pixel StaveStatus: Pixel Stave

Bus

Glued

Glued

Support & Cooling : Stave

Prototype stave has been delivered by HYTEC recently:

Technology Choices: Silicon Pixel Barrels 1 & 2


• Innovative design by BNL Instr. Div. : Z. Li et al., NIM A518, 738 (2004);

• R. Nouicer et al., NIM B261, 1067 (2007);

• R. Nouicer et al., Journal of Instrumentation, 4, P04011 (2009)

• DC-Coupled silicon sensor

• Sensor single-sided

• 2-dimensional position

sensitivity by charge sharing

“New technology: unique to PHENIX”

Technology Choices: Silicon Stripixel Barrels 3 & 4


Sensors produced by HPK with thickness of 625 μm Point-symmetric structure of readout lines wrt the center of the sensor Readout pads in longer edges for

ladder structure design No dead space in the middle Sensor size : 3.4×6.4 cm2

Pixel array : 80×1000 μm2 pitch # readout strip

o x-strip : 128×3×2o u-strip : 128×3×2o Total : 1536 channels/sensor

Current per strip: 0.12 nA

Note: Stripixel sensor technology, including the mask design and processing technology has transferred from BNL to HPK.



Current per strip: 0.12 nA

Note: Stripixel sensor technology, including the mask design and processing technology has transferred from BNL to HPK.


Sensors produced by HPK with thickness of 625 μm Point-symmetric structure of readout lines wrt the center of the sensor Readout pads in longer edges for

ladder structure design No dead space in the middle Sensor size : 3.4×6.4 cm2

Pixel array : 80×1000 μm2 pitch # readout strip

o x-strip : 128×3×2o u-strip : 128×3×2o Total : 1536 channels/sensor


Ladder Design

• Bottom view

Silicon sensor

SVX4 chips

ROC (readout card, ORNL)

• Top view Silicon Module

ADC distributions corrected event-by-event pedestal subtraction

Pedestal = 9.2

Ladder



Response to Proton to Beam at 120 GeV (FNAL, 2008)• Pixel detector • Stripixel detector

- Tracking efficiency

~ 99%

S/N = 10.3

Residual Distribution (row)


Stripixel Ladders Mass Production at BNL Laser scan of

the stave (flatness)Dow Corning glue: 100 [um] Placing modules on stave


EAST: Layer 4 (Stripixel): 12 ladders

EAST: Layer 3 (Stripixel): 8 ladders

Stripixel Barrels Assembly and Testing at the Lab.

WEST: Layer 4 (Stripixel): 12 ladders

WEST: Layer 3 (Stripixel): 8 ladders


Layer 1 (PIXEL): 5x2 ladders

23

Layer 2 (PIXEL): 10x2 ladders

Spiro Board

Pixel Barrels Assembly and Testing at the Lab.


VTX Silicon Vertex Tracker

Layer 2 (Pixel): 10 x 2 = 20

Layer 1 (Pixel): 5 x 2 = 10

Layer 4 (Stripixel): 12 x 2 = 24

Layer 3 (Stripixel): 8 x 2 = 16Full VTX (east + west)

Installed at PHENIX-IRon December 1st, 2010

Layer 1

Layer 2

Layer 3

Layer 4


VTX Survey at the VTX-Lab.Side view of VTX

Final VTX Survey

Ladder survey

Front view of VTX


Full VTX after cabling VTX group and PHENIX technicians

West VTX installed on Nov 17th East VTX installed on Dec. 1 VTX Commissioning at PHENIX-IR

VTX Moved to PHENIX-IR


Operation During Run-11

• Interlock and cooling systems

• Slow control

• Readout

• DAQ

All these systems have been implemented andtested successfully during Run-11 and there areno major plan for modifications. We will only focusto make different systems more robust.

These systems are ready to be used in Run-12


VTX Slow Control and Interlock SystemsCooling systemsStripixel LV Voltage

Pixel LV Voltage Bias Voltage


Stripixel: Readout Chain

DCMII: Zero-SuppressionDetector at the IRStripixel DIB in the rack room

Stripixel ladders

at IR

p+p at 500 GeV

Data Transfer

DIB to DCM2

Optical cables

75 meters

at DIB stage Pedestal Correction:

VTX-Stripixel: Run-11: p+p at 500 GeV

M1 M2 M3

M4 M5 M6


VTX Performance Results

• During RHIC Run-11: (VTX+Central Spectrometers):

- p+p at 500 GeV: 62M (BBC narrow)

- Au+Au at 19.56 GeV:

5M (BBC narrow)

- Au+Au at 200 GeV:

6B (BBC narrow)

- Au+Au at 19.56 GeV:

M (BBC narrow)

• VTX


• Raw hits data from p+p at 500 GeV Beam Data in Stripixel Pedestal correction and zero suppression are working properly

Stripixel: Performance Results


X 100

• Pedestal distribution: RMS

• Clear MIP peak is seen in the cluster ADC distribution• Pedestal width is 5.3 (per stripixel)• S/N = 55/5.16 = 10.7 (at FNAL beam test S/N = 10.3)

S/N in Stripixel Detector



p+p at 500 GeV Multiplicity Distribution

(uncorrected)

• Acceptance of hits distribution(can be used to build reaction plan)

• These basic measurements (multiplicity, flow…) with the VTX are the first step towards a new era of heavy flavor discoveries



VTX at RHIC Run-11: Display of Single Event3) VTX RUN-11: Au+Au at 200 GeV

4) VTX RUN-11: Au+Au at 27 GeV

1) VTX RUN-11: p+p at 500 GeV

2) VTX RUN-11: Au+Au at 19.6 GeV


Track Reconstruction Method

35

B3

B2

B1

B0

VTX

DC+PCRICH

TOFEMCal

VTX

Cen

tral A

rm

2

DC-Track

1We have two complementary methods1. Standalone Tracking method

Only VTX is used Large detector coverage Worse momentum resolution Two algorithms are proposed and

studied to get confident result.

2. DC based tracking with VTX Cluster (DCTVC) DC track is used as a guide and

associated with VTX Clusters Coverage is limited to Central Arm Better momentum resolution

VTX p resolution(sim)DC p resolution


Standalone Tracking: Primary Vertex

• Pixel Primary Vertex in Z • Stripixel Primary Vertex in Z

Primary Vertex for a Single Event:

Peak Position ± 10 bin width is 500 um and 1000 um for pixel and stripixel, respectively. Each bin width corresponds to each pixel size.

• For DCA measurement, the position of the primary vertex need to be determine event-by-event

Run-11 data: Au+Au at 200 GeV


Standalone Tracking: Beam Size


Beam size=104.6 um is consistent with the expected value from beam condition.

• Measurement of DCA from beam fixed center required measurement of beam size

y = 104.6 umx = 133.6 umBeam size


Standalone Tracking: VTX Internal Alignment

Minimum should be at zero

- Stripixel ladders are aligned to the pixel ladders.- The particle has a finite momentum, then particle trajectory bends in B-field. - The residual value between the cluster position and the straight line projection is calculated. If particle has infinite momentum, the residual value should be zero.- We adjust the stripixel position.

Pixel B0

Pixel B1

dproj

θ

B

Stripixel

Pixel ladders

Stripixel ladder


DCA width is: • East σ ~ 137 μm• West σ ~ 142 μm

(Used tracks with pT > 1GeV)

DCA

Standalone Tracking: DCA w.r.t Beam Center• Measured DCA width = Beam spot size (DCA)+

Alignment can improve the DCA resolution

• East σ(DCA) = 88 μm• West σ(DCA) = 96 μm

DCA distribution


DC Based Tracking with VTX Cluster (DCTVC)

DC+PCRich

TOF

EMCal




• Residual distribution () in VTX barrels

- Black: data

- Red: Gaussian fit- Blue: Polynomial fit- Pink: Gaus. + Pol.

barrel 0 barrel 1

barrel 2 barrel 3




• Response of the EMCal Detector

h+ e+h- e-

E/p distribution with enabling Rich detector “n0”

• e± peak should be around 1 but is around 0.8 (full calibration not done yet)


LDTB

• 6 out of 40 LDTBs didn't work well during RUN11 when triggered at high rate.

• With digital oscilloscope, voltage oscillations for 3.3 VD and 2.5 VD regulator, may be also some short period voltage drop.

• Summer repairs: all the stripixel ladders are running properly after replacing the six Tantalum capacitors by Ceramic capacitors on all the LDTB boards; these capacitors stabilize the regulators outputs to the transceivers and FPGA chips.

Stripixel: Summer Repairs


Standalone Test of Troubled Ladders SAMTEC

SAMTEC connector

Popped up GND PIN

Cross section of SPIRO board

Cold soldering

GND pin

EXTENDER LADDER GNDLADDER GND

In RUN11 many pixel ladders couldn't read-out due to GND/Power PIN connection of read-out boards (SPIRO): GND PIN

issue in Samtec connector

Pixel: Summer Repairs

- All boards had been sent to BEST (a company that specialized in PCB rework).

- All fixed boards had been delivered and worked correctly.

Pixel Issue 1

BNL-Nuclear Physics Seminar Rachid Nouicer 4504/21/23 [email protected]

Present Status of VTX: Picture Taken on November 22nd, 2011

FVTX has been built and integrated with VTX

FVTX VTX


VTX and FVTX ready to be moved to PHENIX-IR

east

west

Present Status of VTX: Picture Taken on November 22nd, 2011


SummarySummary

• Construction, installation and commissioning of VTX detector, as well

as sub-systems (interlock, cooling, slow control), were completed

successfully.

• First look on data from p+p and Au+Au from Run-11 show excellent

performance results and indicate that the detector is working properly.

• Now, our efforts are shifted to operation, data analysis and physics

related to the VTX:

• Excellent progress made in software VTX standalone tracking and

global tracking: first look on primary vertex, beam size, DCA…

• Stay tuned! VTX is moving towards new measurements of heavy

flavors leading PHENIX to a new era of discoveries.

Plan: PHENIX/VTX first results will be shown at QM-2012


Thanks to:

• VTX team

• PHENIX Collaboration and technical support • Special thanks to: Yasuyuki Akiba, Ryoji Akimoto, Hidemitsu Asano, Maki Kurosawa, Maya Simomura, Takashi Hachiya, Mikhail Stepanov and Paul Stankus


Auxiliary Slides


Detection efficiency

• Energy deposit in expected CH in layer 2 from the tracking using layer 1 and 3.

50

Layer # All count Count in ADC < 40

Efficiency (%)

2 1697 9 99.5±0.2

count All

40ADC inCount count All Eff

By tracking (x)

By tracking (u)Layer # All count Count in

ADC < 40Efficiency

(%)

2 1559 18 98.9±0.3

50

ProtonBeam

layer 1layer 2layer 3

Results satisfy performance demand Preparing for mass production 50

Sum of ADC in expected CHs (x) in layer2

Sum of ADC in expected CHs (u) in layer2

Hit : >40


First Step: Tests Pulse First Step: Tests Pulse

• Test Pulse: we observed test pulse from detector trough DIBs, DCMs to the

DAQ: conclusion readout chain is working properly


Status of Ladders Mass Production (started on June 3, 2010)• The ladders assembly, testing and survey achieved at BNL using VTX manpower

• Assembly/Survey machine

• Clean room for ladder assembly • Bench test: ladder/silicon modules

• Assembly fixtures


Standalone Tracking: Primary Vertex

• Pixel Primary Vertex in Z

Z(VT

X) (c

m)

Z(BBC) (cm)

• Pixel Primary Vertex in ZPrimary VertexSingle Event:

BBCz vs Pixel detector BBCz vs Stripixel detector

Peak Position ± 10 bin Bin width is 500 um and 1000 um for pixel and stripixel, respectively. Each bin width corresponds to each pixel size.

• Excellent correlation between VTX primary vertex and BBC vertex.

BNL-Nuclear Physics Seminar Rachid Nouicer 1 Brookhaven National Laboratory Research Affiliate of...

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