Pileup Background Rejection Ex, Two protons from one interaction and two b-jets from another Fast Timing Detectors for FP420 z=c(TR-TL)/2  z (mm) =0.21  t (psec) (2.1 mm for  t=10 psec) WHO? UTA (Brandt), Alberta (Pinfold), Louvain (K.P.), FNAL (Albrow) + SACLAY (Royon), Stoneybrook (M. Rij) WHY? How? Compare z-vertex for SVX with TOF How Fast? 10 psec -> x40 to x30 rejection

The Detectors : 1) GASTOF (Louvain)

GASTOF Advantages: Presents little material to beam Extremely fast Disadvantages: No segmentation Long 5 psec

8 fused silica rods in z (my fused silica!) Mike’s idea Jaak’s drawing The Detectors : 2) QUARTIC proton

Fused Silica Bars 9 cm bars Some converted to mini-bars 60 psec Spread in timing as f( ) since n( )

~ 60 ~ 10 p Fused Silica Air light guide (Jim’s) (Aluminium box, or mylar lined plastic) Taper 6  4 (4 is a guess) (Crude “Winston Cone”) Match to photocathode “sweet spot” (mini-bar at 50 deg to p) UTA simulations showed this solution superior to long bars Sketch of Mini-bar Solution dimensions in mm, not to scale

MCP-PMT 2.54 cm 9.0 cm 3.7 cm 4.7 cm 1.53 cm 2.54 cm 50º 2.57 cm 6.4 cm 1.97 cm top view side view top view (photo) QUARTIC Preprototype beam

QUARTIC (V2) Advantages: Segmentation (8 x 4) Compact Disadvantages: More material Not as fast 20 psec

Baseline Plan 1 GASTOF Lots of silicon 2 QUARTICs

T958 Fermilab Test beam experiment to study fast timing counters for FP420 (Brandt spokesman) Used prototype/preprototype detector with expensive or Louvain-made amplifiers and NIM/CAMAC discriminator/TDC to test concept Sporadic mostly parasitic running Aug 12- Sep 14 (primary user Sep 7-10, 14) Time resolution for the full detector system: 1. Intrinsec detector time resolution 2. Jitter in PMT's 3. Electronics (AMP/CFD/TDC)

First TB Initial Results <70 psec/Gastof (2500V) >90% efficiency G1-G2 For QUARTIC bar at 2300V Get 110 psec after correcting for variable height in bar (compared to 90 psec for G at same voltage); Efficiency typically.5 to.6/bar, low of.2, high of.9, at least part of dependence due to CFD performance For events with a few bars on see anticipated √N dependence

Upgrade for T958 Phase II New detector prototypes New electronics Improved DAQ Improved alignment Automated analysis and database routines, to allow instant and easier analysis Improved tracking March 7-20

Burle 8x8 MCP-PMT 25 um pore Amplifier : Hamamatsu Ortec Phillips Constant Fraction Discriminator Ortec 934 (9307) TDC (Phillips 7186) T958 Electronics SMA Lemo Phase I: Phase II: 10 um Burle or 6 um Hamamatsu New boards (Louvain/Alberta) Phase III: HPTDC

Extrapolating Suppose we did no better than first test beam: 67 psec/GASTOF +8bars *.6 eff at 110, this would give 40 psec track measurement or about ~x10 background rejection. Suppose (40,40,30) for QUARTIC (Elec,MCPMT, detector) (64 psec/bar), and.75 efficiency gives 26 psec for one QUARTIC alone, combined with a GASTOF (elec=40,tube=20,det=10) of 44 psec, gives 22 psec track (x18). Ultimately QUARTIC might be (20, 15, 20) but lets assume limit of (25,25,25) gives 11 psec for 2 QUARTICS + GASTOF (15,10,5) gives 18 psec -> total <10 psec

Louvain Electronics: First CFD prototype produced and WORKING!!! Designed a NIM multi-channel board with remote control thresholds(directly from LabView using RS232) New VERY fast (14 GHz BW) amplifiers from Mini-Circuits show very good characteristics Note: One POSITIVE signal output

Q1=Q 10um tube Q11-Q18=12mm bars Q21-Q28=15mm bars Q33-Q36=90mm bars Q2=R 25 um tube R11-R18=12mm bars R21-R28=15mm bars MCP-PMT layout.. beam

Pedro Sean Tomek Andrew Luc Shane FEBRUARY| MARCH M T W TH F S SU M T W TH F S SU M T W TH F S SU M T W TH F S SU M T Personnel Chart/ Time at Fermi

GASTOF Stand

First Results from TB2 QUARTIC Extremely promising 90% efficiency, <70 nsec/bar! Unfortunately, the results were a mirage caused by Coherent noise Furthermore GASTOF2 inefficient and leaks

Coherent Noise! If a row gets blasted, whole tube ground oscillates, 3 nsec later

Coherent Noise! ~3 nsec time

Table shifted 12 mm, to move extra bars out of beam

How to proceed? Grounding other bars at connector did not help Need new tube to fix problem Took data with table offset Took data with scope in remote mode See following talks