10 picoseconds original design goal (light travels 3mm in 10 psec!) gives large factor of background rejection; Phase I: lum up to several  t < 20 ps (<2 year timescale), Phase II:  t < 10 ps (<4 years) Use time difference between protons to measure z-vertex and compare with tracking z-vertex measured with silicon detector Pileup Background Rejection Ex: Two protons from one interaction and two b-jets from another Forward Proton Fast Timing WHY? How? How Fast? Manchester Workshop December 7, 2008 Andrew Brandt (University of Texas, Arlington)

FP420 Baseline Plan 1 GASTOF 2 QUARTICs Lots of 3D silicon Two types of Cerenkov detector are employed: GASTOF – a gas Cerenkov detector that makes a single measurement QUARTIC – two QUARTIC detectors each with 4 rows of 8 fused silica bar allowing up to a 4-fold improvement over the single bar resolution Both detectors use Micro Channel Plate PMTs (MCP-PMTs)

The Detectors : 1) GASTOF (Louvain) Full Cerenkov cone is captured. Simulations show yield of about 10 pe accepted within few ps! 1 measurement of ~10 ps See K.P. Gastof talk for details

4x8 array of 6 mm 2 fused silica bars The Detectors : 2) QUARTIC UTA, Alberta, FNAL Only need 40 ps measurement if you can do it 16 times (2 detectors with 8 bars each)! Has x-segmentation for multi-proton timing proton photons

FP420 baseline timing plan

Fast Timing Personnel ATLAS: UTA (Brandt) QUARTIC development, funding, Test Beam coordination Alberta (Pinfold) Electronics development: HPTDC BNL (White) + Yale (Zeller) Reference timing, apd R&D UC-London (Capmpanelli) Readout Manchester (Kolya) Readout Stonybrook (Rijssenbeek) CFD SACLAY(Ledu) 220 m, phase II timing Chicago (Genat) 220 m, phase II timing SLAC? Other? CMS: Louvain (Piotrzkowski) Gastof development, funding, CFD development Fermilab (Albrow) Ideas, QUARTIC/QUARTZTOF construction, Reference Timing

Fast Timing Is Hard! 3 mm =10 ps Detector Phototube or equivalent Electronics Reference timing Rad Hardness of detector, phototube and electronics, where to put electronics in tunnel Lifetime and recovery time of tube, grounding Background in detector and MCP Multiple proton timing ISSUES Time resolution for the full detector system: 1. Intrinsec detector time resolution 2. Jitter in PMT's 3. Electronics (AMP/CFD/TDC) 4. Reference Timing

Latest QUARTIC Prototype Testing long bars 90 mm (HE to HH) and mini bars 15 mm (HA to HD) Long bars more light from total internal reflection vs. losses from reflection in air light guide, but more time dispersion due to n( ) HE HH HC Note: prior to June 2008 test beam, results marginal for QUARTIC 15mm bar: 80 ps/bar 80% efficient; allows you to reach close to 20 ps, but not 10 ps

QUARTIC 15 mm bar/75 mm guide 20 ps ~ 5 pe’s accepted in 40 ps

QUARTIC 90 mm bar/0 mm guide 40 ps ~ 10 pe’s accepted in 40 ps

June 2008 Test Beam Due bto previous issues with test beam tracking failures, for the June 2008 run we planned to be secondary user for first week with 3dsil group, and primary user for 2 nd week, in order to ensure good tracking Planned laser tests at Louvain prior to TB run; mixed success Planned to have fully functional analysis program, mixed success Main goals of June run to validate detector design, including using tracking for efficiency measurement

Components of Fast Timing System For GASTOF replace CFD/TDC with single photon counter QUARTIC: Photonis planacon 10  m pore 8x8 or equivalent GASTOF: Hamamatsu 6  m pore single channel or equivalent Photek Mini-circuits ZX60 6 GHZ or equivalent Louvain Custom CFD (LCFD) HPTDC board (Alberta) Reference Timing Opto- modules/ ROD HV/LV UTA/Alberta for QUARTIC, PMT, Amp; barter with Louvain for GASTOF? (PMT sold separately!) Stoneybrook CFD BNL/Yale Manchester/UCL

S. White has specified system (presented at Oct. 17 fast timing meeting), I’m sure it will work, but would like to see it tested anyway Optical CFD dominates performance (< 5 ps) Provides average time as well for central event comparison

Test Beam Electronics MCP-PMT Preamplifier SMA LCFD Fast Scope SMA Lemo Fast Scope QUARTIC: Photonis Planacon 10  m pore 8x8 Gastof: Hamamatsu 6  m pore

LCFD Louvain (Luc Bonnet engineer) developed LCFD mini-module approach tuned LCFD mini-module to Burle planacon; 12 channel NIM unit

June 2008 Test Beam Setup trigger paddles3d-sil+Bonn telescope fast timing Cerenkov

FP420 Timing Setup G1 G2 Q1 Amplifiers veto

Data Acquisition Lecroy 8620A 6 GHz 20 Gs (UTA) Lecroy 7300A 3 GHz 20/10 Gs (Louvain) Remotely operated from control room using TightVNC Transfer data periodically with external USB drive UTA funding from DOE ADR grant and Texas ARP grant

Online Screen Capture one histo is 10 ps per bin others are 20 ps histogram delta time between channels FWHM<100 so /2.36 ->dt~40 ps

Determining Pulse Time Burle (HF) Hamamatsu(G1) LCFD (HFc) Linear fit, use 50% time

Dt QUARTIC Long Bars after LCFD 56.6/1.4=40 ps/bar including CFD! Time difference between two 9 cm quartz bars after constant fraction discrimination is 56 ps, implies a single bar resolution of 40 ps

LCFD Resolution Split signal, take difference of raw time and CFD time-> LCFD resolution <27 ps This implies detector+tube ~30 ps

Tracking /Scope Synchronization Tracking shows that bars are highly efficient tracks for all events tracks with a bar on (b)/(a)

Detectors for 20 ps System Primary focus has been on designing detectors that are capable of 20 ps or better timing measurement at low to moderate luminosity (several ) with high efficiency. (Lurking radiation issues, MCPPMT issues discussed later) For GASTOF ~15 ps with 90-99% efficiency depending on position (see K.P. talk) has been achieved for detector/PMT part of path with GASTOF/Hamamatsu (6 um pore), working on improvements, but don’t obviously need them for Phase I. Main issue: there has been no test of CFD/TDC (single photon counter?) and there is no clear readout integration plan For QUARTIC ~40 ps/bar has been achieved with 90+% efficiency including LCFD, separate tests of HPTDC promising (Pinfold talk) Main issue: Still need to demonstrate definitively lack of correlation between measurements allowing Sqrt(n)~4 reduction, MCPMT issues Reference timing of <10 ps does not appear to be a problem, but has not yet been demonstrated R&D funding needed for this

TB Summary June TB two+ weeks of running, tremendous effort 100+Gb of scope data, sizable fraction synchronized with tracking from Bonn telescope Analysis in progress Demonstrated good data, now finalizing results, plan to write a paper soon We potentially have two viable, complementary detector concepts for Phase I Will need more laser tests, simulation and test beam before design is finalized Working on building a U.S. ATLAS collaboration for Phase 1+2 funding (new effort welcome!); Giessen (not in the U.S.) has expressed interest

ATLAS/CMS QUARTIC MCP-PMT Needs For current QUARTIC design, need about a dozen 10  m pores 64 channel Planacon (or Photek equivalent) High rate +current capability needed In contact with Photonis+Photek Better grounding

Draft Phase I Cost Estimate 1 arm220420Total GASTOF$20000$40000 $80000 Gas-$10000 $20000 QUARTIC$20000$40000 $80000 Amplifiers$3200$6400 $13000 CFD$15000$30000 HPTDC$10000$20000 $40000 SPC$20000$40000 $80000 LV/HV$5000$10000 $20000 Ref Timing -$60000 $ ROD$12000$24000 $48000 OptoCrate$10000$20000 $40000 OptoBoards - - $20000 Misc Cables$5000$10000 $20000 TOTAL$310k$610k GASTOF PMT ~$15K May be less than factor of 2 2 QUARTICS PMT~$6k/each $50/ch $240/ch Luc estimate 2X Shengli estimate Single photon counter ~$20k This assumes some infra- structure else will cost more Estimate from Sebastian assuming optocorrelator $30k From Scott—may not have to pay Rod, but probably have to pay OptoBoards and maybe crate? Would like to get this under $500k (reasonable MRI level)

Issues: Radiation Damage Effect of radiation on detector, PMT’s, electronics needs to be evaluated, Potential showstopper -fused silica (should be ok, Alberta will quantify) -GASTOF mirror (should be ok, Louvain will quantify) -Hamamatsu MCP-PMT (some tests at Louvain seemed ok but more studies needed), Burle+Photek not yet tested -SMA cables (should be okay) -LCFD (Louvain will test) -Single photon counter (?) -HPTDC chip and board (Alberta will test) -LV/HV (assume this is provided) Where will the different components be located? (we are assuming amp will be on detector, few meter cable run to LCFD crate/SPC mounted on tunnel wall, HPTDC crate will be here as well) Pin this down at Manchester? Keith, Detlef, Andrew et al Planned cryostat shielding sufficient? Can we get measurements?

Issues: Backgrounds Effect of radiation environment from POV of detector/MCP-PMT response (spray, slow particles) Potential Showstopper -GASTOF+QUARTIC both insensitive to particles incident with a large angle, but slow particles from previous bunch could be a problem, as well as showers arriving with (slightly before) the proton of interest (for example from another proton showering off the bottom of the silicon pocket) -From test beam, particles striking MCP-PMT directly is a concern -> Need to include detectors in full simulation (GASTOF Geant timescale?) QUARTIC Geant4 New manpower Andrei Sobol/Vladimir Samoyenko results Jan/Feb In touch with background group

Issues: MCP-PMT Rate +lifetime capabilities (Major concern) Availability of tubes (Major concern) Radiation (Major concern) Grounding (Major concern)

Coherent Noise! ground oscillation channel hit

Other Issues/TB 220 m modifications needed Multiple proton timing Readout integration At least two more test beams needed (test of final GASTOF prototype, two QUARTIC iterations, readout tests), when where? Spring Fermilab? Summer CERN? 8 channel test+HPTDC test? GASTOF? Enough shifters? Need final laser results first

Fast Timing Workshop Highlights Lots of progress in sampling readout circuits to replace CFD+(TDC?), could be useful for GASTOF, likely overkill for QUARTIC; speed, event size, and rad hardness questions discussed with Gary Varner Hawaii (follow-up?) Japanese group presented new 5 ps CFD option (M.R. investigate) Discussions with Photek, who will try to produce a 75mm diameter round tube with 6 mm pixels, 10 um pores, $50k?! (A.B. will visit in Photek in January) Also have possibility of Photek “solar blind” photocathode 100 nm to 300 nm which could last longer, possibly be interesting Have contact with Garland MCP expert, (A.B. will investigate) Aging is a real issue, but tests are conflicting (Jerry got longer than expected, Nagoya got shorter, but also have an aluminum coating fix that Photonis not too keen on) Lots of test beam results from Chicago, Argonne, FNAL group, discussed Argonne involvement

Issues/Progress TB analysis: continues slowly, UTA very slow due to loss of Shane, plan to write a paper Laser tests: got laser, set up test stand with new Grad student, couple undergrads, making good progress Next QUARTIC prototype: will be built at Alberta using 5 mm square long bars to avoid mixing of channels, they have previous prototype, Alberta working on drawings, A.B. got quote on new bars, $1300 for one detector Sebastian gave good ref timing update at Oct. 17 meeting Good progress on HPTDC (Jim), plan January test at UTA

Multiple proton tracking: 2 nd detector could start with 3mm width and be offset by ½ pixel? Could use Detector 1 to measure yellow and earlier of pink or red Detector 2 to measure red and earlier of pink or yellow (so if pink earlier than red or yellow, measure all 3). For 2 track event would measure both tracks in at least one detector if tracks separated by more than 3 mm, and sometimes if < 3 mm) Final QUARTIC Design Considerations

Jim Pinfold Fiber timing? Advantages, can avoid cracks, use larger region of pmt

Summary Many issues some potentially very serious (radiation, backgrounds, MCP), trying to address in fast timing group (not easy to manage) Still need a coherent work and funding plan (continue FP420 collab as long as possible, how to barter detectors?) Test beam plan needed Suggest bi-weekly meetings of interested parties until all issues are resolved, detectors built Two years is enough time assuming no bad surprises, but not at current activity level, delays in approval/funding becoming critical

Excerpts from FP420 document