Forward TOF Prototyping Ryan Mitchell GlueX Collaboration Meeting November 2005

Purpose of the Forward TOF Particle ID: –π/K separation up to 1.8 GeV/c. Level-1 Trigger: –Fast forward charged track count. Calorimetry: –Tag hadronic showers in the forward calorimeter. Forward TOF Particle ID: 70 ps time resolution 1% momentum and length resolutions

Current Design (and possible improvements) (Not to Scale) 42 bars Scintillators: 252 ×6 × 1.25cm Eljen-200 or Bicron Beam Hole: 12 × 12 cm Hole Photomultiplier Tubes: XP2020 Electronics: Alberta CFD JLab F1TDC fADC Would thicker be better? Is this the best we can do for... timing? fringe field? Need more experience with this (esp. range)...

Outline of Prototyping I: Finished/Ongoing 1.IHEP Test Beams – 2001 to present -- < 80ps resolution is achievable with 200 × 6 × 1.25cm bars -- December 2005 tests will look at 250cm bars IU Cosmic Ray Tests – Spring First measurements were made with a 250 × 6 × 1.25cm bar -- Find 88ps resolution in the center region (2 bars) TRIUMF Beam Test – Summer/Fall Low energy π/μ/e beam used on two layers of scintillators -- Probing time resolution for a variety of dE/dx and all positions -- Discriminator performances

Outline of Prototyping II: 3 Year Plan 1.IU Cosmic Ray Tests – 2006 to Spring Another round of tests with the IU cosmic ray stand ps is not sufficient; look at bar thickness. -- Try a variety of phototubes. -- Use Alberta CFD and commercial CFD and LED. 2.Hall-B Electron/Photon Tests (with LGD) – Fall 2007 Run -- Take the final design to the Hall-B alcove test -- Scan 2 walls of 10 bars each (one full length; one half length). -- Correlate with the LGD and tagger. 3.Magnetic Field Tests (with LGD) – Make sure everything works in the fringe field.

2004 IU Cosmic Rays Summary PMT: XP2020 TDC:LeCroy 2228A (50ps least count) ADC:LeCroy 2249A and IU fADC CFD:Ortec and University of Alberta Scint:250 × 6 × 1.25cm Three movable cosmic ray telescopes in a logical OR. Scintillator is enclosed in a light-tight box (the “coffin”).

2004 IU Cosmic Rays Summary Attenuation Length = ± 4.2 cm Velocity = ± 0.09 cm/ns Time Resolution = 88 ps

2005 TRIUMF Test Beam Summary First two weeks of June and 250 MeV/c π/μ/e beams. Full size and half size scintillators.

Same electronics as cosmic ray tests: PMT: XP2020 TDC: LeCroy 2228A (50ps least count) ADC: LeCroy 2249A and IU fADC CFD: Ortec and University of Alberta Scint: 250 × 6 × 1.25cm 2005 TRIUMF Test Beam Summary

Sample ADC and TDC from one bar end MeV/c π/μ/e beam -- 3 Moyal distribution fit to ADC -- 3 Gaussian distribution fit to TDC e+e+ e+e+ μ+μ+ μ+μ+ π+π+ π+π+

2005 TRIUMF Test Beam Summary Four scans along a front bar. Mean ADC from the two bar ends are superimposed. Attenuation Length = ± 3.4 cm pion muon electron

2005 TRIUMF Test Beam Summary Anomalies in ADC vs TDC Good e+e+ μ+μ+ π+π+ Severe time-walk for electron e+e+ e+e+ e+e+ μ+μ+ μ+μ+ μ+μ+ π+π+ π+π+ π+π+ Double-peak electron Double-peak muon -- Similar behavior for both Alberta and Ortec CFD. -- Needs further analysis. -- Need more tests with different discriminators.

2005 TRIUMF Test Beam Summary π/e separation μ/e separation π/μ separation Four scans along a front bar. TDC differences from the two ends are superimposed. Very consistent run to run results. Nonlinearities are likely due to ADC vs TDC anomalies. Very Important. Needs to be investigated further.

Three Outstanding Design Issues 1.The 88ps resolution for the 252 × 6 × 1.25cm bars is not acceptable. Try doubling the bar thickness. 2.Understand the discriminator issues. Try out a few commercial models (CFD and LED). 3.Explore different phototube options. Can we find something better than the XP2020 for timing and performance in a magnetic field?

Phase I Prototype (2006): Cosmics PLAN: Use the existing IU cosmic ray test stand to explore: -- bar thickness -- discriminators -- phototubes BUDGET: Phototubes: 12k ( e.g. Hamamatsu R9779, Hamamatsu R2083, Hamamatsu R1828, Electron D744, Photek PMT340) Discriminators: 12k (e.g. Ortec 935, Phillips 7106, 708, 710, 715, 730) 2006 Request = 24k

Phase II Prototype (2007): Test Beam PLAN: Test 2 walls of 10 scintillators each (one long horizontal wall and one short vertical wall) in November 2007 along with the LGD. -- use electrons and photons from Hall-B -- scan bars for time and position resolutions. -- correlate the timing with the LGD and the tagger. BUDGET: Phototubes: 18k (instrument 20 bars with XP2020) Scintillators: 5k High Voltage: 25k Cables: 5k Supplies: 6k 2007 Request = 59k

Phase III Prototype (2008): Magnet PLAN: Test the prototype in the magnet fringe field. BUDGET: No new money anticiptated Request = 83k