TOF for ATLAS Forward Proton Upgrade

AFP concept: adds new ATLAS sub-detectors at 220 and 420 m upstream and downstream of central detector to precisely measure the scattered protons to complement ATLAS discovery program.These detectors are designed to run at a luminosity of 1034 cm-2s-1 and operate with standard optics (need high luminosity for discovery physics)

AFP Components1) Rad-hard edgeless 3D silicon detectors with resolution ~10 m, 1rad2) Timing detectors to reject overlap background (SD+JJ+SD)3) New Connection Cryostat at 420m4) “Hamburg Beam Pipe” instead of Roman Pots

beam

p’

p’AFP Detector

LHC magnets

420 m 220 mH

Andrew Brandt, University of Texas, Arlington

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What does AFP Provide?

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Allows ATLAS to use LHC as a tunable s glu-glu or colliderwhile simultaneously pursuing standard ATLAS physics program

420-420

420-220

220-220

Acceptance >40% for wide range of resonance mass

Combination of 220and 420 is key to physics reach!

• Mass and rapidity of centrally produced system

• Mass resolution

of 3-5 GeV per event

4x8 array of 5x5 mm2 fused silica bars

QUARTIC is Primary AFP Timing Detector

Multiple measurements with “modest” resolution simplifies requirements in all phases of system1) We have a readout solution for this option 2)We can have a several meter cable run to a lower radiation area where electronics will be located3)Segmentation is natural for this detector4)Possible optimization with fibers instead of bars

proton

phot

ons

Only need a 40 ps measurement if you can do it 16 times: 2 detectors with 8 bars each, with about 10 pe’s per bar

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UTA, Alberta, Giessen, Stonybrook (w/help from Louvain and FNAL)

MCP-PM

T

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Micro-Channel Plate Photomultiplier Tube

Burle/Photonis 64 channel 10 and 25 m pore 64 channel MCP-PMT has been tested extensively with test beam and laser and would be default for first stage except for lifetime issues

MCP-PMT RequirementsExcellent time resolution: 20-30 ps or better for 10 pe’s High rate capability: Imax ~ 3 A/cm2

Long Lifetime: Q ~ 30 C/cm2/year at 400 nmMulti anode: pixel size of ~6 mm x 6mm Pore Size: 10 m or better Tube Size: 40 mm round, 1 or 2 inch square

Need to have capability of measurements in different parts of tube between 0-2 ns apart, and in same part of the tube 25 ns apart 5

Photek240 (1ch)

HamamatsuSL10 (4x4)

Dt

QUARTIC Timing 2008 CERN TB

56.6/1.4=40 ps/bar using Burle 64 channel 10 mpore tube including CFD!

Time difference between two 9 cm quartz bars after CFD implies a single bar resolution of 40 ps for about 10 pe’s (10 pe’s from simulations/Test Beam).

Npe=(area/rms)2

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2 21 2 1

1

( ) ( ) 2

so if 1 2 then / 2

t t t t

t t

6 mm

6mm

Eve

nts

Strip #

Eff

icie

ncy

(a) (b)

(c)

QUARTIC Efficiency CERN TBAll tracks(Bonn SiliconTelescope)

Tracks witha Quartz bar on

Use tracking (b)/(a) to determine that QUARTIC bar efficiency is high and uniform

Shape due to vetocounterwith 15mmdiameterhole

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Beam Mode Fiber Mode

(a)

(b) (d)

(c)

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UTA Laser System

Time Resolution from Laser Tests

9Laser tests of 10 µm tube show that with sufficient amplification there is

no dependence of timing on gain (low gain operation extends lifetime of tube)

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Saturation from Laser Tests

Saturation independent of number of pixels hit,

with proposed glass can obtain required rate

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Electronics Layout

t~25ps t~5ps

t~5ps

t~15ps

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LOI approved, Technical Proposal being prepared

UK groups funding cut leaves a hole/creates opportunity

We have developed a fast timing system for AFP that seems to be capable of ~10 ps resolution, still some loose ends to address, requires R&D funding

Work in progress:

1) final optimization of detector

2) developing final HPTDC board and trigger circuit

3) test beam analysis and laser tests (including studies of multiple proton effects, lifetime)

4) developing and testing long-life MCP-PMT (need funding)

5) evaluating radiation tolerance of all components

Status