ATLAS Zero Degree Calorimeters

LOI submitted to LHCC by ATLAS collaboration

1 module built and tested in NA SPS beamline

Funds in hand for construction of remaining modules

Operation by end of ‘07 feasible

Fwd workshop – January 2007Sebastian White, Brookhaven Lab

ZDC in ATLASA Zero Degree Calorimeter (ZDC) is a calorimeter that resides at the junction where the two beam pipes of the LHC become one – at 0° from the pp collisions. It is housed in the shielding unit that protects the S.C magnets from radiation, and measures neutral particle production at 0°. It can play many roles.

Outline• ZDC Physics• Installation scenario• ZDC design• ATLAS TDAQ integration• ZDC performance (simulation, rad damage,

testbeam)• Integration with Machine, LHCf• Planning

Reaction plane

x

z

y

z

Spectator neutrons•measure centrality,•Min_min_bias trigger

Beam-Beam Counter Mult/1000(Calorimeter@<2mr.)

Event characterization using forward detectors

>>Direction and magnitude of impact parameter, b

Magnitude from complementary parameters

Nparticipant=2*A-Nspectator

di-jet photoproduction-> parton distributions,x2by with momentum fraction, x14pt

2/s=x1*x2<y>~ -1/2*ln(x1/x2)Signature: rapidity gap in direction(FCAL veto)

x1

x2

Analogous upc interactions and gap structure

diffractive Non-diffractive

Probing small x structure in the Nucleus with N->jets, in Ultraperipheral Collisions(UPC)

ATLAS coverage to||<5 units. Pt ~2 Gev“rapidity gap” threshold

Rates and Kinematics

Event yields from a 1 monthHI (Pb-Pb) run at nominalLuminosity (4 1026 cm-2s-1).Counts per bin of pt=2 GeVx2/x2=+/- 0.25

(with M. Strikman and R. Vogt)

ZDC in pp( Phase II configuration)ZDC in pp( Phase II configuration)

In pp, the ZDC can measure forward production cross sections for several types of particles at very high energies. This will be useful for adjusting parameters for simulations and models, and for cosmic ray physics where the energy in one proton’s rest frame is 1017 eV – a very interesting energy for extended air showers.

What happens when a high energy proton hits the upper atmosphere?

The ZDC can find a pi0 in the midst of several neutrons.

(1M Pythia events analyzed by a ZDC)

RHIC ZDC as an accelerator tool (in pp)

PHENIX horizontal vernier scan Feb. 12, 2003

y = 0.7003x

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1 1.2

Beam displacement (mm)

SMD Readings(mm)

•Van derMeer scan (ZDC coincidence ratevs. relative beam position)•ZDC (lower curve) bkg free over 4 orders of magnitude

•ZDC also measures beam displacement (red points)•Useful for crossing anglecommissioning

Phasing with LHCf run

Phase I

Phase II

EMCal Module design(1 module only)

Light collected fromStrips of 1.5 mm quartzTransverse to beam(main energy and timing)

And 1 mm quartz rodsProjective to beam

Latter measure coordinateOf showers.

Strip detail and airLightguide

648 1.5 mm diameter rods

Provides main energy and Timing measurement

Hadronic module with Coordinate readout( 1 module per arm)

Rods are grouped into4 per readout pixel

Inserting coord readout fibers

Summary of ZDC module parameters

Energy resolution for Photons and neutrons (GEANT simulation)

Coordinate resolution for photons and neutrons

ZDC L1 trigger

• The ZDC trigger will be used primarily as a 2-arm coincidence (each arm above a preset threshold) in Heavy ion runs

• Trigger bits assigned in Central trigger Processor board ctp_cal

• Ctp_cal is designed to accept calib triggers as well as trigger from small systems like the ZDC

Aperture limitations from upstream components of the machine

Background (PYTHIA / GEANT-FLUKA simulation)

Sources of signal and Background

Interaction Point

Decays in Flight

“Walls”

Background (PYTHIA / GEANT-FLUKA simulation)

Sources of Signal and Background

Interaction Point

Decays in Flight

“Walls”

Simulation of kinematic acceptance

~1.8 Grad

~100 Mrad~10 Mrad

~1 Mrad

~100 krad

~10 krad

~100 Mrad~10 Mrad

~1 krad

PMT

Beam

800

180290

150180

30 150100 30

1000150 150150 15090

Ion

iza

tio

n c

ha

mb

er

PMT PMTTAN slot

PMT

MAPMT

MAPMT

Absorbed dose (rad/yr) in TAN at luminosity 1033 cm-2sec-1

We exposed quartz rods at the BNL linac Isotope Producer facility

At 5 Grad absorbed doseLight loss corresponds to A 30% deterioration in Resolution of coord measurement

Test beam exposure in SPS North area parasitic with RP (Oct. ‘06)

Single module exposed to 230 GeV proton beam

Spectra with 0, 10 and 20 cm steel blocks inserted in the beam

Comparison to simulation (note same energy scale used in all Simulations)

Beam tuned to enrich positron componentPeak used to confirm light yield and agreementWith simulations

Tested correlation between coordinate measurement and Position of 2 mm high beam scintillation counters

Summary of cables to USA15

What we are planning

• Install full (8 module) ZDC phased with the LHCf run plan

• Integrate ZDC into ATLAS DAQ and provide a level1 trigger

• Will remove ZDC for highest Luminosity pp runs• Provide a critical role in Heavy Ion program• Important measurements of forward particle

production in pp collisions over full acceptance permitted by TAN constraints

• Funding from US Nuclear Physics program

Schedule

• 1st module completed and tested in beam-no design changes planned

• Construction of mechanical modules can begin 2/07 expect completion in 6/07

• Remaining cables installed this spring• Main schedule uncertainty is daq electronics• Operation possible at end of ‘07 in conjunction

with LCHf detector

Extra slides

ZDC time, space and energy resolution (Average over active area)

Photon energy resolution

ZDC response to neutrons

Neutron energy resolution

Photon space resolution

Neutron spaceresolution

Neutron time resolution

The ZDC scenarios and cables

USA1532 ch

3 +3 ch

32 ch

3 +3 ch

BeamBeam

PHASE I70+6(tr) chs

PMT

Ionizationchamber

PMTPMT

LHCfHad. mod.32+1 chs

Had. mod.1 chs

Had. mod.1 chs

PMT

Ionizationchamber

PMT PMT

LHCf

Had. mod.32+1 chs

Had. mod.1 chs

Had. mod.1 chs

PMTPMT PMT

32 chUSA15

32 ch

4+4 ch

96 ch

4+4 ch

BeamBeam

PHASE II168+8(tr) chs

Ionizationchamber

PMTPMT PMT

EM mod.1 chs

Had. mod.32+1 chs

Had. mod.1 chs

Had. mod.1 chs

Ionizationchamber

PMT PMT

EM mod.96+1 chs

Had. mod.32+1 chs

Had. mod.1 chs

Had. mod.1 chs

Equipment location

• In tunnel at 140 m– 8 ZDC modules– 8 XP3292B Quartz

window PMT’s– 10 Multi anode PMT’s– 138 preamp/driver

chips(5 w total power)– 2 Led driver modules

for monitor system– Patch panels

• In USA15 – Patch panels– 3 VME crates(~300w

power consumption)– PMT HV supplies– Low voltage for

tunnel (5v, 10W)– Trigger signal cable

to LVL-1(USA15)

ATLAS ZDC Schedule

• Draft LOI circulated to ATLAS forward and Heavy Ion Working groups + LHCf - 2/06

• ZDC design completed- 4/06• Radiation Damage studies at BNL - 6/06• 1st module completed -8/06• CERN beam test- 10/06• Presentation to LHCC- ?• Module production completed - 5/07• Ready to install- 7/07

Conclusion

• ATLAS ZDC has unique capability for Heavy Ion as well as pp and beam tuning due to coordinate readout

• Preparation for beam test at CERN and radiation exposure at BNL.

• Have prepared full project file (down to WBS level 4- 150 items)

• Installation of Phase I by summer of ‘07 depending on approval

backup

ZDC Project file (p.1) including Phase II eqpt and labor costs

Concept for remote module replacement

600

965

Absorber

ZDC-modules

Cables

Left/RightUp/Down

Cables

965

Left/Right

760

100180

980

180 150 150

94190

520

9450

BackgroundMARS15:Radiation in TAN, LHCf & ZDC – N.Mokhov TAN Integration – CERN, Mar.10, 2006

Installation• Install in TAN coordinated by LEA/TS(Tsesmelis

group)• Many common issues

– Cabling,lift fixtures– Material activation

• Surveying not critical (~1mm tolerances)• We assume we are responsible for cost of cables,

panels , installation• Have requested Phase I installation ~7/07 (like

CMS) + 4 weeks of checkout• LEA aware of request and considered possible

Installation(II)

• Phase II configuration after LHCf reaches limit (L~1028-1029) for run

• ZDC design rad hard through L=1033, after that will remove for pp runs

• Heavy Ion rad dose negligible.• We are requesting approval from the

collaboration to proceed with LOI submission to LHCC (this is a critical step before we can proceed with installation)

di-jet photoproduction-> parton distributions,x2by with momentum fraction, x14pt

2/s=x1*x2<y>~ -1/2*ln(x1/x2)Signature: rapidity gap in direction(FCAL veto) and leading neutron from beam fragments

Probing small x structure in the Nucleus with N->jets, heavy flavor.

ZDC role in Heavy Ion Physics (event tag for hard photoproduction)

Leading Particle in peripheral collisions

-> ZDC tag in Heavy Ions analogous to Roman Pot tag in pp

ZDC cable detail

top view ofassembled holder

material - copper4 peace with grooves1 peace w/o grooves

1.12.1

1 2.16 6 6 11 11 6 6 6 5.55.5

3 3

6

4

75

250

X-Y rod holder

Assembling module: installing X-Y rods

Bare module

Rod is put in module and measured

Rod is removed, cut to size and replaced

All rods installed

Rod is put in module and measured

Rod is removed, cut to size and replaced