1. THE FORWARD PROTON DETECTOR AT DZERO Gilvan Alves Lafex/CBPF 1) MOTIVATION 2) DETECTOR OPTIONS 3) FPD R&D 4) OUTLOOK Lishep 98 Lafex/CBPF Feb 17, 1998

2. p Beam pFpF P Diffractive Kinematics  Rapidity Gap Approach  Need to Tag and Measure p( p ) p p Detector

3. Y - Pot X - Pot Beam Axis 8  Beam Envelope 14.4mm 20mm 6.8mm 0.8mm The Detector UVX Planes

4. DETECTOR GOALS Position resolution of 100µm Efficiency close to 100% Radiation Hardness High Rate capability Low background rate Small dead area close to the beam

5. ACCEPTANCE Quadrupole ( p or ) Dipole ( only) Dipole acceptance better at low |t|, large  Cross section dominated by low |t|  0 0.02 0.04 1.4 1.4 1.3 2 35 95 Quadrupole Dipole M X (GeV) 450 400 350 280 200 GeV 2 450 400 350 280 200 M X (GeV)   Geometric  Acceptance

6. DETECTOR OPTIONS

8. Photon Detection Device Quantum Efficiency Light  Charge VLPC (  80%) APD (  70%) Image Intensifier CCD (  20%) Low rate MAPMT (  20%) VLPC the best option But... cryogenics$$$

9. DETECTOR OPTIONS Fiber Options Investigated  Scint. Tile to Clear Fiber  Scint. Tile to WLS Fiber  Scint. Fiber Straight  Scint. Fiber to Clear Fiber  Round vs. Square Fibers

10. DETECTOR OPTIONS Scint Tile 800  m thick Clear Fiber Scint Tile 800  m thick WLS fiber 4fibers  PMT 2 WLS fibers  PMT

11. DETECTOR OPTIONS Scint Fibers 800  m Scint Fibers 800  m Clear fiber Mirrored side 4fibers  PMT

12. DETECTOR OPTIONS Pot Detector Active Area XY Plane UV Plane Pot

13. DETECTOR OPTIONS Square Fibers Increase light Yields by  20%  Scint. Tile to Clear Fiber or WLS discarded for low yield  Reduce Pot Size Using tilted planes (U,V)  Fiber bend does not affect performance(limited to  = 5cm)

14. Single PE Measurement H6568 Scint. Tile + Clear Fiber =3.0 LED Calibration.

15. Scint. Fiber Output H6568 Effect of cutting Fiber at 45  =7.3 =6.8

16. Similar to Uncut Straight Fibers Gain Attenuation length Losses due to Cutting Fiber at 45  (5%) Fiber Splicing (5-10%) # Preferred Option Accelerator Background Cross Talk Scint. Fiber + Clear Fiber Output H6568 =7.4

17. Cross Talk Results H6568 1.3mm window thickness Improved by new 0.8mm window Using Scintillating Fibers w/o EMA => 25% increase

18. Efficiency Measurement Use 106 44 Ru 3.5 MeV e - Source Source Collimator D T1 T2 D - Detector Cell T1&T2 - Trigger Scintillators  = 90-95% (not corrected for  background)

19. Six planes (u,u’,v,v’,x,x’) of 800  scintillator fibers (’) planes offset by 1/3 fiber THE DETECTOR 20 channels/plane(U,V)’ 16 channels/plane(X,X’) 112 channels/detector 2016 total channels 80  teor. resolution

20. 4 Fiber bundle fits well the pixel size of H6568 16 Ch. MAPMT 7 PMT’s/detector (most of the cost) THE DETECTOR U U’

21. SUMMARY Fiber Detector represents the best option Prototype being built for beam/cosmic tests FPD will be a completely integrated sub-detector of the  detector which will help  maximize Run II physics potential Hard diffraction needs large data samples and precise measurements