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 Andrew Brandt UTA110/14/2009 QUARTIC, Laser Tests, +Lifetime Andrew Brandt, University of Texas at Arlington

4x8 array of 6 mm 2 fused silica bars QUARTIC UTA, Alberta, Stonybrook, Giessen, (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

10/14/2009Andrew Brandt UTA3 Micro-Channel Plate Photomultiplier Tube Burle/Photonis 64 channel 10  m pore

Dt QUARTIC Timing 2008 CERN TB 56.6/1.4=40 ps/bar including CFD! Time difference between two 9 cm quartz bars after Louvain constant fraction discrimination is 56 ps, implies a single bar resolution of 40 ps for about 10 pe’s (expected 10 pe’s from simulations). Need to demonstrate  N (wait for it…) N pe =(area/rms) 2 4

Baseline ATLAS Solution: QUARTIC Multiple measurements each with modest resolution on ps scale simplifies requirements in all phases of system. QUARTIC advantages: 1) Have a solution in-hand for full readout chain 2) Segmentation allows multi-proton timing and L1 trigger 3) Only amplifiers have to be near detector, CFD’s and TDC’s can be located further away (timing distortion in cable is a negligible effect for this detector design) Final optimization in progress, may replace quartz bars with quartz fibers, will likely have variable width in x to improve multi-proton res., trigger capability, rate and lifetime (1.5 mm, 3 mm, 6 mm, 12 mm) Andrew Brandt UTA512/12/2009

AFP Timing Progress in 2009 Established UTA Picosecond Test Facility (PTF) for laser tests Developing in depth understanding of MCP-PMT performance Investigated rate and lifetime issues Collaborating with Arradiance, Photek, and Photonis Built a new prototype detector for  N tests (Alberta) Validated readout electronics (Jim’s talk) Investigating fiber-based QUARTIC (Wei-lin’s talk) Settled on QUARTIC as baseline detector 10/14/2009Andrew Brandt UTA6

Anode Current = proton frequency x number of photo-electrons generated by each proton x gain x charge If current is too high (~10% of strip current) the tube saturates (gain is reduced) From laser tests timing is ~independent of gain as long as With 10 pe’s expected for a QUARTIC bar, would need to operate at a gain of ~5x10 4. With proton rate of 15 MHz in 6 mm closest to beam at 220 m at a luminosity of 10 34, we would require a maximum current of about 3  A/cm 2, a factor of several higher than standard MCP-PMT’s, but possible for new generation of Photonis MCP-PMT’s (smarter binning reduces to 1  A/cm 2 ) 10/14/2009Andrew Brandt UTA7 Rate and Current Limits

Lifetime Issues Lifetime due to positive ions damaging the photocathode is believed to be proportional to extracted charge: Q/year = I*10 7 sec/year Q for 3  A/cm 2 is 30 C/cm 2 /yr Without a factor of 20 reduction in gain, the current and lifetime issues would make MCP-PMT’s unusable, with it the rate is borderline, but lifetime off by up to factor of 50— tube dies every week! Andrew Brandt UTA810/14/2009

Options for Improved Lifetime MCP-PMT Ion barrier, already demonstrated, this promises a factor 5 to 6 lifetime improvement (at the cost of a 40% collection efficiency reduction) Electron scrubbing, already demonstrated internally by Photonis, promises a factor 5 to 10 lifetime improvement Z-stack, already demonstrated, this promises a factor of 10 lifetime improvement (A.Yu. Barnyakov, et al., Nucl. Instr. and Meth. A 598 (2009) 160) Arradiance coated MCP’s, to be demonstrated, this promises a factor of 10 or more lifetime improvement (Grants submitted by UTA and Manchester to fund insertion of Arradiance MCP’s in Photonis and Photek tubes: “Development of a Long Life Microchannel Plate Photomultiplier Tube for High Flux Applications through the Innovative Application of Nanofilms”) Various combinations of these factors are possible and should give multiplicative improvement factors, except for the electron scrubbing and Arradiance coating, which would be expected to be orthogonal 910/14/2009Andrew Brandt UTA Pursuing funds to commission, purchase, and test longer lifetime tubes. Photek will build tubes to our specification, Photonis will insert Arradiance modified MCP into their tubes

Laser Test Goals Develop useful flexible laser test facility Study properties of MCP-PMT’s Optimize electronics  Some issues to address: 1)How does timing depend on gain ? 2)What is minimum gain for 10 pe’s? Need to validate low gain operations. 3) What is maximum rate at which tube can operate? 4)Evaluate amp/CFD/TDC choices at detector working point 5) Eventually lifetime tests 1010/14/2009Andrew Brandt UTA

LeCroy Wavemaster 6 GHz Oscilloscope Laser Box Hamamatsu PLP-10 Laser Power Supply Andrew Brandt UTA1110/14/2009 laser lenses filter MCP-PMT beam splitter mirror PTF Picosecond Test Facility featuring Undergraduate Laser Gang (UGLG) Undergraduate Laser Youths? (UGLY) Typically use 405 nm laser diode also have 632 nm laser head

10  m Laser Setup with Reference Tube (3/17/09) Reference Tube (~6 ps) Andrew Brandt UTA EE Meeting1211/16/2009

Andrew Brandt UTA Timing vs Gain for 10 pe’s (10  Burle) Measured with reference tube using CFD’s and x100 mini-circuits amps, with 10 pe’s can operate at ~5E4 Gain (critical for reducing rate and lifetime issues) 13

Further 10 pe Timing Studies 14 Providing sufficient input voltage to CFD leads to improvement in CFD resolution: now gives negligible contribution to total resolution. Varying exact details of amplifiers attenuators, etc. can affect results by a few ps (at low gain ~25 ps for 405 nm)

10/14/2009Andrew Brandt UTA15 Timing vs. Number of PE’s

Wait a Minute! Jerry Va’vra has measured 32 ps for TTS (SLAC-PUB-13573) so we should have about 10 ps (32/  10 for 10 pe’s! ) This is true only if you ignore 2 nd backscattering peak! We are modeling effect of recoil electrons on timing 7/14/2009Andrew Brandt UTA Prague AFP Meeting16

UTA Transit Time Spread for Burle 64 Channel Planacon (10  m pores) Increase filter until only 1/10 events have a signal, isolates 1 pe. Time difference with respect to reference tube 7/14/200917Andrew Brandt UTA Prague AFP Meeting

10/14/2009Andrew Brandt UTA18 Current/area for 10  m Tube Last 2 points are 0.4 and 2.0 μA/cm 2 ; we need to reach about 3 μA/cm 2 at Photonis has made Planacon with 10x higher current capability which would meet our rate requirements (even with saturation we still obtain the same time resolution!!!)

New Multi-Channel Laser Setup 10/14/2009Andrew Brandt UTA19

Rate Tests with Multiple Pixels Hit 10/14/2009Andrew Brandt UTA20 No rate dependence on number of pixels hit (that’s a good thing!)

Beam vs Fiber Fiber timing not as good, but allows us flexibility for some characterization tests

If single fiber gives 35 ps then 4 fibers should give 17 ps; but note that with many fibers plugged in, individual pixel gets light leaking from neighboring channel, need to test that this effect is reproduced in test beam SQRT(N)? From averaging time of four measurements on event-by- event basis

SQRT(N)? 10/14/ Measure time difference of three separate fibers (100 pe’s) w/respect to reference tube, correct for T0 offset, average and take new time difference w/respect to reference tube (expect about 9.5 get 10.3 ps ) Andrew Brandt UTA

Fast Timing Summary Have tested detectors and electronics chain capable of ~10 ps timing Have developed flexible laser facility (PTF) R&D still in progress to optimize all components PMT lifetime is an ongoing issue, but pursuing options with vendors that seem likely to provide solutions on 3 year timescale 10/14/2009Andrew Brandt UTA24