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

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

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  1. 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 < h < +4 STAR Forward Meson Spectrometer (FMS)Lead-glass calorimeter / STATUS

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

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

  4. 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 High Voltage Systems

  5. PC Light-tight, ventilated enclosure (half of FMS) +9V/2.4A Up to16 controllers of either type USB to I2C +30V/1.2A -6/0.5A Up to16 PSU bases Up to16 Yale bases as inE864 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

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

  7. QT32 with 4 QT8 daughter cards QT8 daughter card Electronics and TriggerHank Crawford, Fred Bieser, Jack Engelage, Eleanor Judd, Chris Perkins, et al. (UC Berkeley/SSL) • 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

  8. South FMS rack, servicing 632 detectors North FMS rack, servicing 632 detectors • 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. QT1 Crate 1/12 QT boards QT3 Crate 12 QT boards QT2 Crate 12 QT boards QT4 Crate 12 QT boards FMS Crate 16 DSM boards

  9. Au Au FMS Commissioning Summed Energy (ADC cnts) Cell multiplicity Commissioning of FMS during Run 7Ready for Production Now and in Run 8 QT gate North Large Cell Row-2 / Col-11 • 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

  10. FMS for d-Au saturation physics p+p and d+Au  p0+p0+X correlations with forward p0 p+p in PYTHIA d+Au in HIJING hep-ex/0502040 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.

  11. Three Highlighted Objectives In STAR Forward Meson Spectrometer Proposal[hep-ex/0502040] • A d(p)+Aup0p0+X measurement of the parton model gluon density distributions xg(x) in gold nucleifor0.001< x <0.1. For 0.01<x<0.1, this measurement tests the universality of the gluon distribution. • Characterization of correlated pion cross sections as a function of Q2 (pT2) to search for the onset of gluon saturation effects associated with macroscopic gluon fields. (again d-Au) • Measurements withtransversely polarized protonsthat are expected toresolve the origin of the large transverse spin asymmetriesin reactions for forward  production. (polarized pp)   DOE milestone 

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