Pileup Background Rejection

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

FPF420@UTA

The Detectors : 1) GASTOF

http://www.fynu.ucl.ac.be/themes/he/ggamma/Cherenkov/

(Louvain)

GASTOFAdvantages:• 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()

206

6

4

4

~ 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 cm2.54 cm

9.0 cm

3.7 cm

4.7 cm

1.53

cm

2.54

cm

50º2.57

cm

6.4 cm

1.97cm

top view

side view

top view (photo)

QUARTIC Preprototype

beam

QUARTIC (V2)Advantages:• Segmentation (8 x 4)• CompactDisadvantages:• More material• Not as fast

20 psec

Baseline Plan1 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 resolution2. Jitter in PMT's3. Electronics (AMP/CFD/TDC)

First TB Initial Results

<70 psec/Gastof (2500V)>90% efficiency

G1-G2For QUARTIC bar at 2300VGet 110 psec after correctingfor variable height in bar(compared to 90 psec forG 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-PMT25 um pore

Amplifier :HamamatsuOrtecPhillips

Constant Fraction DiscriminatorOrtec 934(9307)

TDC(Phillips 7186)

T958 Electronics

SMA 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 tubeQ11-Q18=12mm barsQ21-Q28=15mm barsQ33-Q36=90mm bars

Q2=R 25 um tubeR11-R18=12mm barsR21-R28=15mm bars

21 11 31

22 12 31

23 13 33

24 14 34

25 15

26 16

27 17

28 18

. .

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 T26 27 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27

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 byCoherent noise

Furthermore GASTOF2 inefficient and leaks

Coherent Noise!

If a row gets blasted, whole tubeground 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 helpNeed new tube to fix problem

Took data with table offsetTook data with scope in remote mode

See following talks