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PrimEx at 12 GeV and Requirements to Calorimeter

PrimEx at 12 GeV and Requirements to Calorimeter. Outline PrimEx Physics @ 12 GeV Geometrical Acceptance and Resolutions Requirements to Calorimeter. A. Gasparian NC A&T State University, Greensboro, NC. 1. Experimental program 1) Precision measurements of:

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PrimEx at 12 GeV and Requirements to Calorimeter

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  1. PrimEx at 12 GeV and Requirements to Calorimeter Outline • PrimEx Physics @ 12 GeV • Geometrical Acceptance and Resolutions • Requirements to Calorimeter A. Gasparian NC A&T State University, Greensboro, NC Cal. Workshop 1

  2. Experimental program 1) Precision measurements of: Two-Photon Decay Widths: Γ(0→), Γ(→), Γ(’→) Transition Form Factors at low Q2 (0.001-0.5 GeV2/c2): F(*→0), F(* →), F(* →) (D. Dale talk) The PrimEx Project at 12 GeV 2) The η rare neutral decays (L. Gan talk) Cal. Workshop 2

  3. Physics Motivation Fundamental input to Physics: • precision test of chiral anomaly predictions; • determination of light quark mass ratio; • -’ mixing angle; • 0, and ’ interaction electromagnetic radius; • is the ’ an approximate Goldstone boson? Cal. Workshop 3

  4. PrimEx @ 12 GeVPrecision Measurement of → decay width • All  decay widths are calculated from  decay width and experimental Branching Ratios (B.R.): Γ(η→ decay) = Γ(→) × B.R. • Any improvement in Γ(→) will change the whole - sector in PDB Cal. Workshop 4

  5. Physics Outcome from  Experiment • light quark mass ratio •  - ’ mixing angle Γ(η→3)=Γ(→)×B.R. Cal. Workshop 5

  6. ρ,ω Primakoff Method 12C target Primakoff Nucl. Coherent Interference Nucl. Incoh. Challenge: Extract the Primakoff amplitude Cal. Workshop 6

  7.  Experiment with GlueX Advantages: • High energy tagged photon beam Eγ=10 – 11.5 GeV • High acceptance electromagnetic calorimeter (FCAL) • Solenoid detector to veto charged particles, and reduce background on FCAL • Targets (~1-5% R.L.): • LH2, • LHe4, • solid 12C Challenges: • Photon flux stability and control: possible solutions: • e+e- pair spectrometer; • Compton scattering; • High resolution Calorimeter requires for precision experiments: possible solution: • Pb-glass + PbWO4 crystals • Or All PbWO4 Calorimeter Cal. Workshop 7

  8. Geometrical Acceptance vs. Calorimeter Size • A Calorimeter with 118 x 118 cm2 size will already provide ~70% geometrical acceptance, which is enough for this experiment. • ’→ experiment will require a larger size Calorimeter. A. Gasparian Cal. Workshop 8

  9. Production Angle Resolution • Precision Primakoff measurement requires high resolutions in: • production angle; FCAL with all Pb-glass FCAL + PbWO4(35x35 blocks (70x70 cm2) FCAL + PbWO4(75x75 blocks (150x150 cm2) Cal. Workshop 9

  10. Invariant Mass Resolution FCAL with All Pb-glass FCAL + PbWO4(35x35 blocks (70x70 cm2) FCAL + PbWO4(75x75 blocks (150x150 cm2) Cal. Workshop 10

  11. The minimum size: 118 x 118 cm2 will be enough for the first experiment • Best resolutions in Energy and Position are Required for the precision extraction: • Energy: 1.3% @ 1 GeV is essential; • Position: 1.4 mm @ 1 GeV is essential. Requirements to Calorimeter • Fast time response is essential: < 100 ns is important. • Smaller Moliere radius is essential: to provide small granularity to provide better resolutions of overlapping showers. ~ 2 cm is already enough. • Modular structure is required: to provide optimum shape of the Calorimeter in different experiments. Cal. Workshop, Oct. 31 2008

  12. The End A. Gasparian Cal. Workshop 12

  13. Readout of PbWO in Magnetic Field Required Modifications: • change the G10 housing to sift ion housing and extend it (~2”) • insert optical extension • extend the brass strips • reassemble modules FCAL with PbWO4 insertionis critical for our physics The optical wrapping of Crystal should not change Cal. Workshop

  14. HYCAL (Crystal part) Cal. Workshop

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