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1Brookhaven National Laboratory2University of California- Berkeley3Pennsylvania State University4IHEP, Protvino5Stony Brook University6Texas A&M University7Utrecht, the Netherlands

8Zagreb University

FMS status - June 2007F.Bieser2, L.Bland1, E. Braidot7, R.Brown1, H.Crawford2, A.Derevshchikov4, J.Drachenberg6, J.Engelage2, L.Eun3, M.Evans3, D.Fein3, C.Gagliardi6, S.Hepplemann3, E.Judd2, V.Kravtsov4, J. Langdon5, Yu.Matulenko4, A.Meschanin4, C.Miller5, D.Morozov4, M.Ng2, L.Nogach4, S.Nurushev4, A.Ogawa1, H. Okada1, J. Palmatier3, T.Peitzmann7, S. Perez5, C.Perkins2, M.Planinic8, N.Poljak8, G.Rakness3, A.Vasiliev4, N.Zachariou5

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Three Highlighted Objectives In STAR Forward Meson Spectrometer Proposal

[hep-ex/0502040]

1. A d(p)+Aud(p)+Au+X+X measurement of the parton model gluon density distributions xg(x) in gold gold nucleinuclei for 0.001< 0.001< xx <0.1 <0.1. For 0.01<x<0.1, this measurement tests the universality of the gluon distribution.

2. Characterization of correlated pion cross sections as a function of Q2 (pT

2) to search for the onset of gluon saturation effects associated with macroscopic macroscopic gluon fields. gluon fields. (again d-Au)(again d-Au)

3. Measurements with transversely polarized transversely polarized protonsprotons that are expected to resolve the origin of resolve the origin of the large transverse spin asymmetriesthe large transverse spin asymmetries in reactions for forward forward production. production. (polarized (polarized pp)pp)

DOE milestone

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FPD -> FMS

The FPD originated as a test cell for the EEMC and has evolved into a 2mx2m forward spectrometer providing new physics results with each run

Run-5 FPDRun-6 FPD++Run-7 FMS

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Any difference between p+p and d+Au?

Kharzeev, Levin, McLerran gives physics picture (NPA748, 627)

Color glass condensate predicts that the back-to-back correlation from p+p should be suppressed

Frankfurt and Strikman:Frankfurt and Strikman:Explains our RExplains our RdAudAu result with result with black center nucleusblack center nucleus (>10% energy loss) (>10% energy loss)

and only peripheral events contributing to leading pion production.and only peripheral events contributing to leading pion production.Also explain suppression of away jet with combinatorics.Also explain suppression of away jet with combinatorics.

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How do we tell if there is a CGC?

ln(1/x) and the scale (Q) is taken as pT

Require two (jets) in FMS probes smallest x gluons in Au nucleus (largest )Look for broadening or disappearance of peak as pT decreases

pT decreasing

We will map the Q2 - X space

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FMS for d-Au saturation physicsFMS for d-Au saturation physicsp+p and d+Au ++X correlations with forward

hep-ex/0502040p+p in PYTHIA d+Au in HIJING

Conventional shadowing will change yield, but not angular correlation. Saturation will change yield and modify the angular correlation.

Sensitive down to xg ~ 10-3 in pQCD scenario; few x 10-4 in CGC scenario.

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The STAR FMS is a ~2m x 2m lead-glass wall west of the STAR interaction point viewing collisions through the hole in the STAR magnet poletip. In conjunction with the barrel and endcap EMC, the addition of the FMS realizes a “full-acceptance detector” with electromagnetic calorimetry for -1 < < +4

STAR Forward Meson Spectrometer (FMS)Lead-glass calorimeter / STATUS

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d+Au +X at 200 GeV

pT dependence of d+Au π0 cross section at <η> = 4.0 is best described by a LO CGC calculation.

(Dumitru, Hayashigaki, and Jalilian-Marian, NPA 765, 464)

nucl-ex/0602011

STARSTAR

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π0 AN at √s=200 GeV – xF-dependence

• AN at positive xF grows with increasing xF

• AN at negative xF is consistent with zero

• Run 6 data at <η>=3.7 are consistent with the existing measurements

• Small errors of the data points allow quantitative comparison with theory predictions

• Theory expects the reverse dependence on η

Phys.Rev.D74:114013,2006Phys.Rev.D74:114013,2006..

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A-single- study using PythiaHiromi Okada

What is Ex point for R=Nall/N

direct=1? With VETO, Without VETO (VETO: Large cells)

Pythia condition:• MSELL=0,• MSUB=(11,12,13,28,53,68,81,82,86,87,88,89,92,93,94,95,1,2) and

(14,18,29,114,115). inelastic=41.12 [mb]

• CKIN(5)=1,CKIN(6)=1,CKIN(3)=0,CKIN(4)=-1. Select “A single events”

• Acceptance: FPD++ small cells• VETO FPD++ large cells (See page 2)

Results Without VETO EX=43 GeV (Intersecting point of black and pink histograms in page 3) With VETO EX=26 GeV (This value can be improved

by better choices for "acceptance" and "veto“).

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Single photon acceptance

Acceptance (Small cells)

Veto (Large cells)

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A single events in acceptance (FPD++ inner cells)

from 0 (Without VETO) from (Without VETO)

Direct-

43 GeV E from 0 (With VETO)

L=0.9 pb-1

3.81010 calls

WITHOUT VETO

Pythia simulation

Intersecting point of black and pink histograms

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Cell details

Large Cells / 788 in total

(5.8cm)2 x 60.2 cm lead glass

18.75 radiation lengths

XP2202 photomultiplier

5.8cm

60.2 cm

Small Cells / 476 in total

(3.8cm)2 x 45 cm lead glass

18 radiation lengths

FEU84 + XP2972 photomultipliers

170 small cells prior to wrapping

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STAR Forward Meson Spectrometer (FMS)Lead-glass calorimeter / STATUS

Detectors are stacked on the west platform in two movable halves. This view is of the south FMS half, as seen through the retracted west poletip.

Schematic of the FMS as seen from the interaction point. The small-cell inner calorimeter has 476 detectors and the large cell outer calorimeter has 788 detectors.

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High Voltage Systems

Large cells / 788 in total

XP2202 phototube powered by Zener-diode-stabilized resistive voltage divider, with high-voltage delivered by

four 256-channel LeCroy 1440 main frames

Small cells viewed by FEU-84 224 in total

Cockcroft-Walton system for FEU-84 designed/built by Steve Heppelman,

Len Eun, et al. at Penn State University

Small cells view by XP2972252 in total

Existing phototubes and bases courtesy of Yale University, from AGS-E864

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Up to16 controllers of either type

Up to16 PSU bases

Up to16 Yale bases

PC

USB to I2C

Light-tight, ventilated enclosure (half of FMS)+9V/2.4A

+30V/1.2A

-6/0.5A

as in E864

Two PC-controlled 256-channel Cockcroft-Walton control systems designed/built by Steve Heppelmann, Len Eun, et al. (Penn State) for small-cell inner calorimeter HV control

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PSU controllers

Master controller

Yale controllers

Yale bases PSU bases

Resistive bases

High-voltage systems as implemented in north FMS half

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Electronics and TriggerHank Crawford, Fred Bieser, Jack Engelage, Eleanor Judd, Chris Perkins, et al.

(UC Berkeley/SSL)

QT8 daughter card QT32 with 4 QT8 daughter cards

Readout of 1264 channels of FMS provided by QT boards. Each board has

• 32 analog inputs

• 12-bit ADC / channel

• 5-bit TDC / channel

• five FPGA for data and trigger

• operates at 9.38 MHz and higher harmonics

• produces 32 bits for each RHIC crossing for trigger

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South FMS rack, servicing 632 detectors

QT1 Crate 1/12 QT boards

QT2 Crate 12 QT boards

FMS Crate 16 DSM boards

Present Status

• 37/48 QT boards mounted in 9U VME in STAR Wide Angle Hall;

• all QT boards ready for installation;

• QT2,QT3,QT4 crates connected to phototubes and tested operational;

• Trigger connections completed; tests after run ends.

North FMS rack, servicing 632 detectors

QT3 Crate 12 QT boards

QT4 Crate 12 QT boards

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Commissioning of FMS during Run 7Ready for Production Now and in Run 8

• completed: cell-by-cell scans of HV to check HV and signal connections

• completed: quadrant-by-quadrant total-energy measurements

• completed: initial timing for QT electronics

Au Au FMS Commissioning Au Au FMS Commissioning

Cell multiplicityCell multiplicity

Summed Energy (ADC cnts)Summed Energy (ADC cnts)

QT gate

North Large Cell

Row-2 / Col-11

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QT status

Currently have 3/4 of QTs operating. Expect to add final 1/4 next week.

Have verified sensitivity as <0.25 pC/count

Have verified absence of correlated noise; single channel rms~0.6 cts

Linear over full range to <1%

Expect to test L0 trigger capabilities this week

Building multi-LED programmable system for testing trigger pattern capability - for use this summer

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Future

We expect to explore at least two upgrades to the FMSTo allow us to investigate forward π0 production and theExpected asymmetries using the 250 GeV pp beamsAnd to explore QCD Drell-Yan processes producing charged Leptons.Both of these concepts require a position sensitive detector at the front of the FMS; the second requires tracking through a magnetic field.