QUARTIC, A TOF for ATLAS/CMS Forward Protons

1. You didn’t know that ATLAS+CMS had forward protons? FP420 = Forward Protons 420m downstream of CMS & ATLAS (joint R&D project) Physics is p H/WW/ZZ p Measure p’s with very high precision within 3 mm of beam Gives mass and quantum numbers of central state. QUARTIC, A TOF for ATLAS/CMS Forward Protons Andrew Brandt (UTA) Jim Pinfold (Alberta), Mike Albrow (FNAL)

2. FP420 Challenges  Tracker, perhaps 10 layers per station, 3 stations, 3D silicon (edgeless, 10um res., fast, rad hard) .... Hawaii/SLAC + Brunel • TOF counter, quartz fiber Cerenkov + MCP-PMTs • Vacuum mechanics: Detectors in secondary vacuum, space constraints between beam pipes, not room for roman pots. High precision movement (microns), reproducibility, fail-safe. • Funding, approvals, etc.

3. particle Cerenkov Effect n=1 n>>1 Use this property of prompt radiation to develop a fast timing counter

4. It’s been done! Can’t put our PMT in 7 TeV beam!

5. QUARTIC Preliminary UTA drawing of Mike Albrow’s concept for a fast time resolution Cerenkov counter: Initial design used 2 mm2 rods, but not enough light, this drawing shows 6mm2 rods proton z (mm) =0.21 t (psec) (2.1 mm for t=10 psec) z=c(TR-TL)/2 Microchannel plate PMT

6. Where do Protons go at 420m 120 GeV Higgs courtesy Peter Bussey, Manchester (irony of particle physics—easier to get plot of protons from Higgs than single diffraction) y x<2.5 cm 3mm x x x

7. A GEANT4 simulation is well underway (see GEANT4 produced graphics above. The detector simulation includes: Tracking of Cerenkov photons to the MCP-PMT through the medium. Wavelength dependent refractive index of the medium Wavelength dependent attenuation of the photons Wavelength dependent reflectivity of the aluminium reflector Timing of photons from generation to the MCP-PMT The effects of coupling grease (if necessary) GEANT4 Simulation (Alberta)

8. QUARTIC Background Rejection (UTA) • 2 single diffractive protons overlayed with a hard scatter (1% of • interactions have a proton at 420m) 97.4% of events primary vertex and fake vertex from combining proton times more than 2.1mm (1) apart ; 94.8% if 20 psec 2) double pomeron overlayed with a hard scatter 97.8% of time vertices more than 2.1mm apart; 95.6% if 20 psec 3) hard SD overlayed with a soft SD 95.5% of time primary vertex and fake vertex more than 2.1mm apart; 91.0% if 20 psec

9. maybe we should call it Fusstic Cerenkov Light in Fused Silica (UTA): UV is important! 640-650 total pe’s : 130 pe/6mm rod

10. Preliminary Time Distributions: Single  n=1.52 c=49; 7.4% of pe’s in 10 psec 21.3% in 50 psec red = totally internally reflected light green = extra light if aluminized 0.01 • over  including QE 1.9% of pe’s in 10 psec 19.1% in 50 psec 0.01 50 psec 50 psec

11. Preliminary design studies are promising Need to learn more about MCP’s; preliminary indications are Burle tubes are currently only option due to size of active area Burle 85021 600 has 1.5 mm pixels could give very useful x-segmentation for measuring multiple protons in same detector, but it seems that best timing using single MCP_OUT channel (1/tube) (Wilma Raso) Starting to think about electronics (Alberta) Test beam at Fermilab summer 2006 Next Steps