Test Beam Studies for FP420 Fast Timing Developers: UTA (Brandt), Louvain, Alberta, FNAL WHO? TB shifters: UTA, UC-London, Louvain, Prague WHY? Pileup Background Rejection Ex: Two protons from one interaction and two b-jets from another Use time difference between protons to measure z-vertex and compare with tracking z-vertex measured with silicon detector How? How Fast? 10 picoseconds original design goal (light travels 3mm in 10 psec!) gives large factor of background rejection; phased plan, start with 20 ps (<2 year timescale), need better than 10 ps for full machine luminosity (<4 years) Picosecond Workshop October 16, 2008 IPNL, Lyon

Fast Timing Is Hard! ISSUES 3 mm =10 ps Detector Phototube Electronics Time resolution for the full detector system: 1. Intrinsec detector time resolution 2. Jitter in PMT's 3. Electronics (AMP/CFD/TDC) 3 mm =10 ps Detector Phototube 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

FP420 Baseline Plan 2 QUARTICs 1 GASTOF 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) Not so much light since use gas, but full Cerenkov cone is captured. Simulations show yield of about 10 pe accepted within few ps! 1 measurement of ~10 ps

The Detectors : 2) QUARTIC 4x8 array of 6 mm2 fused silica bars UTA, Alberta, FNAL Only need 40 ps measurement if you can do it 16 times (2 detectors with 8 bars each)! proton photons

First TB Results ( Fall 2006) G1-G2 For QUARTIC bar 110 psec Efficiency 50-60% For events with a few bars on see anticipated √N dependence <70 psec/Gastof (Burle 25 um 8x8 tube, 4 pixels) >90% efficiency, dominated by CFD resolution (used Ortec 934)

Threshhold discrimination March 2007 Test Beam (t)=45 ps (t)=35 ps Threshhold discrimination CFD algo simulated QUARTIC 80 ps/bar (15 mm bar) 80% efficient if G1=G2 then t=25 ps each, but G1 has faster tube (Hamamatsu 6 m pore vs 25 m Burle) and better mirror; extract resolution G1=13 ps G2=32 ps, initial estimate 80% efficient

Latest QUARTIC Prototype HC HH HE 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()

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

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

June 2008 Test Beam In between Mar 2007 and June 2008 had two largely unsuccessful test beams due primarily to tracking failures; for the June run we planned to be secondary user for first week with 3dsil group, and primary user for 2nd 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

Electronics SMA Lemo QUARTIC: Photonis Planacon 10 m pore 8x8 Gastof: Hamamatsu 6 m pore single channel or equivalent Photek Electronics Experiment channel Louvain Custom CFD (LCFD) Mini-circuits ZX60 6 GHZ or equivalent HPTDC board (Alberta) interfaces to ATLAS Rod For GASTOF replace CFD/TDC with single photon counter MCP-PMT Preamplifier SMA LCFD Fast Scope Lemo (b) or (c) TB channel

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

June 2008 Test Beam Setup fast timing Cerenkov 3d-sil+Bonn telescope trigger paddles comment on alignment

FP420 Timing Setup G2 G1 Q1 Amplifiers

Data Acquisition Lecroy 8620A 6 GHz 20 Gs (UTA) Lecroy 7300A (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

Good Trigger is Important Spray event add veto

channels in adjacent rows Coherent Noise! channels in adjacent rows

Good Event 5 ns/major division

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

Offline Analysis Too cumbersome, not getting results in timely manner I implement streamlined approach + round the clock analysis shifts (one data taking shifter, one analysis shifter: Nicolas, Vlasta, Shane) -start with basics -plot pulses -pulse heights -low threshold cut -raw times -time differences -add tracking later overflow -> switch from 100 to 200 mv scale acceptance

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

QUARTIC Long Bars after LCFD 56.6/1.4=40 ps/bar including CFD! Dt 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 All tracks Early tracking results: 88% of tracks 170<x<260 have HEc bar on 98% have HF on (lower threshold) Timing does not seem to depend on whether or not there is a track (efficiency is high)-> can use all non-tracking data HEc On 6mm

HF Efficiency 6 mm fraction of events with good track and HF bar on as a function of track position 6 mm

GASTOF Displaced 19 mm See Schul talk All tracks for more details Multiple scattering effects in 400 um wide, 30 cm long stainless steel edge of GASTOF (cause veto)! 1mm depletion implies tracking projection issues, detector tilted slightly, or both GASTOF On dip ~1 mm wide edge

What to Measure: QUARTIC Data taking still in progress (lost a graduate student) Dependence of efficiency, pulse height, time resolution on bar type and position, HV, 0 vs 1 vs 2 amps, as f(scope resolution 50 vs 100 ps, 3 vs 6 ghz) Before and after shift in veto counter Also have some 25 m tube data ``Time track’’ using all channels

QUARTIC vs GASTOF Do we need both? G one (or two) measurements 10-20 ps need to figure out readout integration Q multiple measurements 40 ps each 10-20 ps overall, some multi-proton capability, integration into readout through HPTDC, need to demonstrate N improvement of 8 bars Different background characteristics I think answer is still yes

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 this year I believe that we have two viable, complementary detector concepts 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!)

ATLAS/CMS MCP-PMT Needs For current QUARTIC design, need about a dozen 10 m pores 64 channel Planacon (or Photek equivalent) High Rate capability (at 420 m 1% of interactions have a scattered proton). Start with 13 MHz (75 nsec bunch spacing). Few interactions per crossing, <1 MHz over 12.5 cm2 so should be okay. At max luminosity, 25-30 interactions/crossing at 40 MHz 40 MHz -> 10 MHz over area, may be okay? 220 m, situation is ~3 times worse! Need high current capability to improve lifetime of tube: I calculate 10 C over tube in 100,000 hours (1/5 of year) at low luminosity (using 80 pe/event and gain of 106 ) Better grounding Dropped faceplate? Other minor improvements? Phase 1 vs phase 2