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HvH, DNP Oct 2007

The FVTX detector in PHENIX

Hubert van Hecke, Los Alamos National Laboratory

for the PHENIX collaboration

Vtx (Mannel)

Fvtx (HvH)

RPC (Wei)

TOF (Belmont)

RPC gas (Wood)

RPC (Kim)

RPC (Meredith)

Computing (Love)

Forward Silicon Vertex Detector,one of a number of detector upgrades

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FVTX team

R. K. Choudhury, P. Shukla, D. Dutta, A. K. Mohanty, Bhabha Atomic Research Centre, India; R. Pak, K.A. Drees, Brookhaven National Laboratory; H. Pereira, Saclay, France; M. Finger, M. Finger, Charles University, Prague, Czech Republic; J. Klaus, Czech Technical University, Prague, Czech Republic; P. Mikes, J. Popule, L. Tomasek, M. Tomasek, V. Vrba; Institute of Physics, Academy of Sciences, Prague, Czech Republic; B. Cole, E. Mannel, D. Winter, W. Zajc, Columbia University; J.C. Hill, J.G. Lajoie, C.A. Ogilvie, A. Lebedev, H. Pei, G. Skank,A. Semenov, G. Sleege, F. Wei, Iowa State University; Naohito Saito, KEK, Japan; T. Murakami, K. Tanida, Kyoto University, Japan; J.G. Boissevain, M.L. Brooks, S. Butsyk, G. Grim, H.W. van Hecke, J. Kapustinsky, A. Klein, G.J. Kunde, D.M. Lee, M.J. Leitch, H. Liu, M.X. Liu, P.L. McGaughey, A.K. Purwar, W.E. Sondheim, Los Alamos National Laboratory; Hisham Albataineh, G. Kyle, V. Papavassiliou, S. Pate, X.R. Wang, New Mexico State University; T. Alho, M. Bondila, R. Diaz, D. J. Kim, J. Rak, University of Jyvaskyla, Finland; B. Bassalleck, D.E. Fields, M. Hoeferkamp, M. Malik, K. Spendier, J. Berndt, University of New Mexico, Albuquerque; J.H. Kang, Y. Kweon, Yonsei University, Korea

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HvH, DNP Oct 2007

Goals of the FVTX

Use heavy quarks (c,b) to study properties of the QGP q, g contributions to p spin Drell-Yan

Signal channel: b->B-> c->D-> J/, ’->

+

-

B,D have finite lifetimes, so they can be identified with a vertex tracker

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HvH, DNP Oct 2007

Separate signal from backgrounds

Solution:D, B mesons travel ~1mm (with boost) before semileptonic decay to muons

Mean ,K decay distance is much larger

By measuring the DCA to the primary vertex, we can separate D, B decays from prompt muons and from long-lived decays from , K

The problem: backgrounds (-> and K-> ) overwhelm the signal

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HvH, DNP Oct 2007

Detector Specifications

• Need sufficient DCA resolution (~100um) • Need occupancy low enough to find tracks in central AuAu events (<few %)• Need enough hits to reconstruct a track (>=3 hits)• Need to match tracks with Muon System: = 1.2 - 2.4

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HvH, DNP Oct 2007

Model the detector

SensorHDI

Geant-3-based simulations

3.750

12.5 cm1664 strips13 chips

2.8mm strip

11.2mm strip

75-um strips

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HvH, DNP Oct 2007

Other materials

Materials that affect us: - barrel silicon layers (4) - support and cooling structures - cabling and connectors - beam pipe - electronics board

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DCA resolutions

Since the barrel pixels are // to the beampipe (orthogonal to the FVTX mini-strips, using them greatly improves phi resolution

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Occupancy

Max track density in central Au+Au ~7/cm2

Max. strip occupancy ~ 2.8% -> choose 75 m strips

/cm2

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Using DCA cuts, plus and isolation cuts, we can now improve the signal/background for D,B->

Open charm, bottom signal

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HvH, DNP Oct 2007

Simulated RHIC-II p+p run - better background . rejection - better mass resolution - separate ’

Without FVTX

With FVTX

Improved resolution + background reduction

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HvH, DNP Oct 2007

Mechanical design and prototypes

Silicon sensor prototype from ON Semiconductor, CZ, under test at UNM

Main unit: ‘wedge’

Carbon backing

Kapton HDI

Silicon

Readout chipsMin Tº = 15ºC

Max Tº = 20.3ºC

Max deflection10.4μm

Heat flow studies

Mechanical distortion studies

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HvH, DNP Oct 2007

Mechanical design ~80% done

Wedge -> Disk -> Cage assembly

Thermally conducting silicone

Honeycomb support panel

Wedges front and back

Cooling inlet 15°C

Cooling out 16.1°C

Support cage

40 cm

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Readout chain

1) FVTX readout chips2) ROC read-out card nearby3) FEM front-end module outside experimental hall

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HvH, DNP Oct 2007

1) Readout chip (FPHX)

Readout chip being designed at FNAL

Derived from FPIX family of chips (BTeV), with (small) modifications

‘Pushes’ data to ROC - total bandwidth up to ~3.5 Tbps

Low power: 100 W/channel, 50W total / 4 disks

2x13 chips per wedge, 128 channels / chip

Total # channels: ~1.0M

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2) ROC - readout card

- One ROC combines data from 26 FPHX chips, send zero-supressed data to FEM over optical link

- Download masks and thresholds to FPHX

- Send clocks

- Control calibration board

- Implemented in rad-hard Actel FPGA

8-chip HDI

USB Interface

Actel Starter Board

prototype

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3) FEM: front-end-module

- FEM buffers data by beam crossing, 64 clocks deep

- Deliver event upon LVL-1 trigger to Phenix DAQ

- Send clocks down to IR

- Implemented in Xilinx FPGA

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Calibration using FPIX chips and readout cardprototype:

Threshold / noise ~ 18:1

Test with prototype readout chip and ROC

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Status and outlook

Software:

- Simulations and analysis - in hand

Hardware:

- Silicon detector prototypes undergoing tests

- FPHX chip being layed out

- HDI (Kapton interconnects) being layed out

- Readout electronics chain prototyped and running

- Mechanical design ~80% done

- Construction start in FY08

- Installation in Phenix in summer 2011

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backups

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External mount

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Acceptance

Since the event vertex spans~+-10 cm in z, we can use the barrel hits for some events.

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HvH, DNP Oct 2007

Can we match muon arm tracks with a FVTX track?

3 GeV muon: 75% correct match 9 GeV muons;

93% correct match

Use the chi2 of the Kalman track fitter :

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