1. 1 1 Brookhaven National Laboratory 2 University of California- Berkeley 3 Pennsylvania State University 4 IHEP, Protvino 5 Stony Brook University 6 Texas A&M University 7 Utrecht, the Netherlands 8 Zagreb University FMS status - June 2007 F.Bieser 2, L.Bland 1, E. Braidot 7, R.Brown 1, H.Crawford 2, A.Derevshchikov 4, J.Drachenberg 6, J.Engelage 2, L.Eun 3, M.Evans 3, D.Fein 3, C.Gagliardi 6, S.Hepplemann 3, E.Judd 2, V.Kravtsov 4, J. Langdon 5, Yu.Matulenko 4, A.Meschanin 4, C.Miller 5, D.Morozov 4, M.Ng 2, L.Nogach 4, S.Nurushev 4, A.Ogawa 1, H. Okada 1, J. Palmatier 3, T.Peitzmann 7, S. Perez 5, C.Perkins 2, M.Planinic 8, N.Poljak 8, G.Rakness 3, A.Vasiliev 4, N.Zachariou 5

2. 2 Three Highlighted Objectives In STAR Forward Meson Spectrometer Proposal [hep-ex/0502040] d(p)+Au     +X gold nuclei 0.001< x <0.1 1.A d(p)+Au     +X measurement of the parton model gluon density distributions xg ( x ) in gold nuclei for 0.001< x <0.1. For 0.01< x <0.1, this measurement tests the universality of the gluon distribution. macroscopic gluon fields. (again d-Au) 2.Characterization of correlated pion cross sections as a function of Q 2 (p T 2 ) to search for the onset of gluon saturation effects associated with macroscopic gluon fields. (again d-Au) transversely polarized protons resolve the origin of the large transverse spin asymmetries forward   production. (polarized pp) 3.Measurements with transversely polarized protons that are expected to resolve the origin of the large transverse spin asymmetries in reactions for forward   production. (polarized pp)  DOE milestone 

3. 3 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 FPD Run-6 FPD++ Run-7 FMS

4. 4 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: Explains our R dAu result with black center nucleus (>10% energy loss) and only peripheral events contributing to leading pion production. Also explain suppression of away jet with combinatorics.

5. 5 How do we tell if there is a CGC?  ln( 1/x) and the scale (Q) is taken as p T Require two   (jets) in FMS  probes smallest x gluons in Au nucleus (largest  ) Look for broadening or disappearance of  peak as p T decreases p T decreasing We will map the Q 2 - X space

6. 6 FMS for d-Au saturation physics p+p and d+Au    +   +X correlations with forward   hep-ex/0502040 p+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 x g ~ 10 -3 in pQCD scenario; few x 10 -4 in CGC scenario.

7. 7 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

8. 8 d+Au    +X at 200 GeV p T dependence of d+Au π 0 cross section at = 4.0 is best described by a LO CGC calculation. (Dumitru, Hayashigaki, and Jalilian-Marian, NPA 765, 464) nucl-ex/0602011 STAR

9. 9 π 0 A N at √s=200 GeV – x F -dependence A N at positive x F grows with increasing x F A N at negative x F is consistent with zero Run 6 data at =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.D74:114013,2006.

10. 10 A-single-  study using Pythia Hiromi Okada What is E x point for R=N  all /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 E X =43 GeV (Intersecting point of black and pink histograms in page 3) With VETO E X =26 GeV (This value can be improved by better choices for "acceptance" and "veto“).

11. 11 Single photon acceptance Acceptance (Small cells) Veto (Large cells)

12. 12 A single  events in acceptance (FPD++ inner cells)  from  0 (Without VETO)  from  (Without VETO) Direct-  43 GeV EE  from  0 (With VETO) L=0.9 pb -1 3.8  10 10 calls WITHOUT VETO Pythia simulation Intersecting point of black and pink histograms

13. 13 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

14. 14 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.

15. 15 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 XP2972 252 in total Existing phototubes and bases courtesy of Yale University, from AGS-E864

16. 16 Up to16 controllers of either type Up to16 PSU bases Up to16 Yale bases PC USB to I 2 C 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

17. 17 PSU controllers Master controller Yale controllers Yale basesPSU bases Resistive bases High-voltage systems as implemented in north FMS half

18. 18 Electronics and Trigger Hank 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

19. 19 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

20. 20 Commissioning of FMS during Run 7 Ready 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 Cell multiplicity Summed Energy (ADC cnts) QT gate North Large Cell Row-2 / Col-11

21. 21 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

22. 22 Future We expect to explore at least two upgrades to the FMS To allow us to investigate forward π 0 production and the Expected asymmetries using the 250 GeV pp beams And 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.