QUARTIC- A Precise ToF Detector for the FP420 Project

1. QUARTIC- A Precise ToF Detector for the FP420 Project James Pinfold For the QUARTIC Working Group René Magritte: Empire of Light

2. The QUARTIC Working Group • University of Alberta: Lars Holm, James Pinfold, Drew Price, Jan Schaapman, Yushu Yao • Fermilab: Mike Albrow • University of Texas at Arlington:Andrew Brandt, Chance Harenza, Joaquin Noyola, Pedro Duarte Associated Group • University of Louvain: Krzysztof Piotrzkowski James Pinfold Manchester Meeting December 2005

3. Initial Conception of Quartic • AIM: Use a precise ToF Cerenkov detector to match z(vertex) with central track vertex and thus reduce backgrounds to, for example, exclusive diffractive Higgs production • Z of interaction = c(TR-TL)/2 where TR(TL) is the time measured in the RHS(LHS) QUARTIC detectors (420m from IP) - • We have Dz (mm) =0.21 Dt (psec) (2.1 mm for Dt=10 ps [cDt/√2]) TR TL X We are aiming for ~10ps resolution (3mm at the speed of light) t TL z_vtx z TR James Pinfold Manchester Meeting December 2005

4. Where do the Protons Go? y 120 GeV Higgs x 120 GeV Higgs SD Background ALL (420m+420m) 3mm 3mm X- cms X- m James Pinfold Manchester Meeting December 2005

5. proton Initial Geometry for QUARTIC* * From Mike Albrow Cerenkov Photons MCP-PMT 20 fused silica bars 6mm2 x 100 mm NB fused silica is rad-hard James Pinfold Manchester Meeting December 2005

6. Achieved – a 10ps Timing Resolution The problem is we cannot put a PMT in a 7 TeV beam. James Pinfold Manchester Meeting December 2005

7. What is aMCP-PMT? The MCP-PMT is a micro channel plate equipped with a photocathode & (usually) a multi-anode readout Burle 2” MCP-PMT James Pinfold Manchester Meeting December 2005

8. The detector simulation includes: Tracking and timing of Cerenkov photons to the MCP-PMT Wavelength dependent refractive index, attenuation & reflectivity Ability to study cladding (eg air) or a reflective layer (with a possibility of including diffuse reflection) The effects of coupling grease (if necessary) Geant4 Simulation (Cladding with NA=0.37) Al reflection James Pinfold Manchester Meeting December 2005

9. Simulating the MCP-PMT • Arrival time at the face of the MCP-PMT recorded • Simulate geometrical acceptance • Implement wavelength dependence of the photo-cathode QE. • Simulate PMT transit-time jitter by adding a normally distributed random time jitter with the appropriate standard deviation • Simulate the layout of the anode pad readout of the MCP-PMT. • Assume that when the MCP-PMT o/p voltage reaches a certain level it triggers the discriminator – this level corresponds to a certain number of photons having arrived. James Pinfold Manchester Meeting December 2005

10. Cerenkov Light in Fused Silica* UV is important! 640 total pe’s : ~130 pe’s/6mm rod (collection efficiency reduces this number to ~80 pe’s/bar) *UTA simulation James Pinfold Manchester Meeting December 2005

11. Photon Arrival Times (1) (From Ray Tracing) QE not included red= totally internally reflected light green= extra light if aluminized First 10ps 22 photons First 20ps 51 photons First 30ps 80 photons First 40 ps 107 photons Half maximum rise time ~3ps Number of photons Picoseconds James Pinfold Manchester Meeting December 2005

12. Photon Arrival Times (2) (From Ray Tracing) QE included red= totally internally reflected light green= extra light if aluminized First 10ps 3 pe’s First 20ps 8 pe’s First 30ps 12 pe’s First 40ps 16 pe’s Half maximum rise time ~3ps Number of photoelectrons Picoseconds James Pinfold Manchester Meeting December 2005

13. QUARTIC Background Rejection (1) Rule of thumb: ~1% of interactions have a proton at 420m • 2 single diffractive protons overlapping a hard scatter • A hard scatter with an overlapping double pomeron event • A hard single diffractive event overlapping a soft diffractive event FV PV 97.4% of events have primary (PV) vertex and fake vertex (FV) more than 2.1mm (1) apart. SV PV 97.8% of events have primary (PV) vertex and second vertex (SV) more than 2.1mm (1) apart. FV PV 95.5% of events have primary (PV) vertex and fake vertex (FV) more than 2.1mm (1) apart. James Pinfold Manchester Meeting December 2005

14. Background Rejection (2) • Two single diffractive protons overlapping a hard scatter • A hard scatter with an overlapping double pomeron event • A hard single diffractive event overlapping a soft diffractive event Background rejection James Pinfold Manchester Meeting December 2005

15. Frontend Readout (1st version) • High precision Alberta CFD Aiming for 20-ps resolution. • Using CERN HPTDC as key component.  • Dead time free. • 32 channels/chip。 Size～2.7×2.7 cm2。 • External clock：40MHz。Synchronized to bunches. • Time resolution (RMS)： • 70ps medium resolution mode • 35ps high resolution mode • 15ps very high resolution mode (8ch per chip)。 • Double pulse resolution：5ns (typical); 10ns (guaranteed). Separate leading or trailing edge measurement; • Simultaneous measurement of leading edge and pulse width (not true for very high resolution mode). James Pinfold Manchester Meeting December 2005

16. Test-beam at Fermilab • Planned for summer of 2006 (beam starts in mid-June) • Test-beam manned by UTA and Alberta • Online/DAQ development required for QUARTIC prototype readout. • Optical pulser & scope (TDS6804) will be used to validate electronics prior to test-beam • Constant Fraction Discriminator+ HPTDC will be used to readout the detector • Full sized prototype of detector available – but not all channels readout James Pinfold Manchester Meeting December 2005

17. Responsibilities • Design (Joint responsibility): • Conceptual: geometry - bars, plates, block, fibers, other?) • Optimization • Engineering • Simulation (Alberta + UTA): • full GEANT- 4 (Alberta), ray tracing (UTA) • Radiator (UTA + Fermilab): • Fused silica • Surface treatment: aluminization, cladding, ... • Photodetector (UTA + Alberta) • MCP-PMT: Hamamatsu, Burle, other? (Baseline solution) • SiPMT, Avalanche photodiode (APD)?, other ? • Mechanics, Assembly and mounting (UTA, Alberta): • Engineering and manufacture (including motion control) • Electronics (Alberta + UTA) • Front end Read-out • HV and slow controls James Pinfold Manchester Meeting December 2005

18. Funding Initiatives UTA (with UofA listed as a collaborator): Texas ARP $100K/2 years, TOF and Mechanics; passed University pre-proposal stage (12/79); proposal due Feb. 14, award May 15 DOE ADR $130k/2 years, TOF only, proposal due Dec. 15! Award date June. Burle is contributing MCP-PMT’s 25mm pore (60 psec TTS), 10mm pore (~30 psec expected), 10um, dropped face plate (removes tail from recoil electrons), and high current capability version Alberta A small amount of initial funding is available(~$10K). In kind contribution from small electronics and machining costs (at 5CHF/hr!) James Pinfold Manchester Meeting December 2005

19. Conclusion • The QUARTIC precision ToF detector offers the possibility of reducing physics backgrounds to exclusive central Higgs production at ATLAS • ToF detector resolutions of ~10ps have been achieved previously and initial simulation studies indicate that we should be able to deploy a detector with resolution of better than 30ps at the LHC • This resolution will allow us to reduce the background from events contributing central “activity” and two protons at 420m (hard scatters + diffractive & double pomeron events) by more than 90%. • The R&D effort to develop QUARTIC is well underway with the first beam-test to take place in the summer of 2006. James Pinfold Manchester Meeting December 2005

20. particle Cerenkov Effect n=1 n>>1 Use this property of prompt radiation to develop a fast timing counter James Pinfold Manchester Meeting December 2005

21. Readout Electronics (1st take) James Pinfold Manchester Meeting December 2005