Drift Chamber Review March 6-8, 2007 1 Overview of Requirements Forward and Central Drift Chambers Elton S. Smith Jefferson Lab Physics goals Overview

1Drift Chamber Review March 6-8, 2007

Overview of RequirementsForward and Central Drift Chambers

Elton S. Smith

Jefferson Lab

Physics goalsOverview of Hall DTracking requirementsSimulation

2Drift Chamber Review Mar 6-8, 2007

Physics goals and key featuresThe physics goal of GlueX is to map the spectrum of hybrid mesons (gluonic excitations) starting with those with the unique signature of exotic quantum numbers. Normal mesons in the quark model cannot have exotic JPC.

Identifying JPC requires an amplitude analysis which in turn requires• linearly polarized photons• detector with excellent acceptance and resolution• sensitivity to a wide variety of decay modes

In addition, sensitivity to hybrid masses up to 2.5 GeV requires 9 GeV photons which will be produced using coherent bremsstrahlung from 12 GeV electrons.

Final states include photons and charged particles and require particle identification.

Hermetic detector with large acceptance for charged and neutral particles


The GlueX Detector Design has been driven by the need to carry out Amplitude analysis.

p

X

n,p

Photoproduction

1 → a+1 → ()() →

h0 → bo1→ () →

Final state particles ± K± p

h’2 → K+1K− → o K+ K− → +−K+K−

1 1 ’1 b2 h2 h’2 b0 h0 h’0

all charged

many photons

strange particles

1−+ 2+− 0+−

Search for QCD Exotics

Mass scale ~ 2 GeV


Event Topologies

t-channel meson photoproductionIncident 8-9 GeV t) ~ e- t

photonspions

protons

~1

Ge

V/c

10-60o

~5

GeV

/c

<20o

p→1(1800)p


Physics Requirements

GlueX is designed to search for JPC exotic particles which are identified in a partial wave analysis of exclusive final states.

The detector must have uniformity of response and hermiticity to minimize false sources of exotic waves (“leakage”).

Leakage can be affected by incomplete knowledge of the detector acceptance and by purity of the event sample.

We have chosen a solenoidal detector configuration (B = 2T) to provide an azimuthally symmetric and well-understood acceptance.

Gluonic excitations are expected to have typical hadronic widths and decay modes with relatively high multiplicities.

Sensitivity to multiple decay modes requires good momentum and angular resolution for both photons and charged particles.


6 GeV CEBAF

CHL-2CHL-2

Upgrade magnets Upgrade magnets and power and power suppliessupplies

12

Enhance equipment in Enhance equipment in existing hallsexisting halls

add Hall D (and beam line)


Overview of Hall D

Hall D is a new experimental hall to be located on the east side of the north linac

The project includes the design, construction and commissioning of the photon beam and experimental equipment in Hall D.

The detector incorporates existing hardware

• Solenoid magnet used for the LASS experiment at SLAC and the MEGA experiment at LANL

• Lead glass used in BNL E852

The GlueX physics collaboration (approximately 70 people from 25 institutions) has been active for seven years

The GlueX collaboration is leading the detector R&D and conceptual design efforts in Hall D.


Top View

75 m

Tagger AreaExperimental

Hall D

Electron beam

Coherent Bremsstrahlungphoton beam

Solenoid-Based detector

Collimator

PhotonBeam dump

Photon beam and experimental area

East arc

North linac

Tagger area

Hall D

ElectronBeam dump


Hall D Detector Layout

Electron Beam from CEBAF

Lead GlassDetector

Solenoid

Coherent BremsstrahlungPhoton Beam

CerenkovCounter

Time ofFlight

BarrelCalorimeter

Note that tagger is80 m upstream of

detector

Target

Central DriftChambers (CDC)

Forward Drift Chambers (FDC)


The experiment has sought out expert advice by requesting external reviews

Cassel Committee (Dec 1999) David Cassel (chair), Frank Close, John Domingo, William Dunwoodie, Donald Geesaman, David Hitlin, Martin Olsson, Glenn Young GlueX Electronics (Jul 2003) John Domingo, Andy Lankford (chair), Glenn YoungGlueX Detector Review (Oct 2004) Mike Albrow, Jim Alexander (chair), William Dunwoodie, Bernhard MeckingSolenoid Assessment (Nov 2004) John Alcorn, Robert Kephart (chair), Claus RodeReview of Tagging Spectrometer and Photon Beamline (Jan 2006) Juergen Ahrens (chair), Bernhard Mecking, Alan Nathan

The collaboration has responded to issues raised by these committees and developed the present solid foundation for further design and construction

Hall D/GlueX Reviews

Note: GlueX has also been reviewed by PAC23 (Jan 2003), PAC27 (Jan 2005), the DOE Science Review (April 2005), and PAC30 (Aug 2006)


The GlueX collaboration has designed and optimized the detector to study gluonic excitations. Many university groups have contributed to the R&D and development of major subsystems.

• Solenoid JLab, IU Cyclotron Facility

• Detectors• Tracking Carnegie Mellon, Ohio, JLab

• Calorimetry Alberta, Athens, Florida State, Indiana, Regina

• PID Indiana, Inst for High Energy Physics (Protvino), Oak Ridge, Tennessee, Florida

International

• Computing Carnegie Mellon, Connecticut, Indiana, JLab, Regina

• Electronics Alberta, Christopher Newport, Guanajuato, Indiana, IU Cyclotron Facility, JLab

• Beamline Catholic, Connecticut, Glasgow

• Infrastructure JLab

Institutional Responsibilities

Elke Aschenauer took over as Hall D group leader in December, 2006. The Hall D group was officially formed in the Physics Division and 12 GeV project in January.


Capability Quantity Range

Charged particles Coverage 1o < < 140o

Momentum Resolution (5o-140o) p/p = 1 − 3%

Position resolution ~ 150-200 m

dE/dx measurements 20 < < 140o

Time-of-flight measurements t < 60 ps

Cerenkov and /K separation < 14o

Barrel time resolution t < (150 + 50 /√E) ps

Photon detection Energy measurements 2 < < 120o

Veto capability < 170o

LGD energy resolution (E > 100 MeV) E/E = (3.6 + 7.3/√E)%

Barrel energy resolution (E > 20 MeV) E/E = (2 + 5/√E)%

LGD position resolution x,y, ~ 1 cm

Barrel position resolution z ~ 4 cm

DAQ/trigger Level 1 200 kHz

Level 3 event rate to tape 15 kHz

Data rate 100 MB/s

Electronics Fully pipelined Flash ADCs, multi-hit TDCs

Photon Flux Initial: 107 /s rate Final: 108 /s

Hall D Scope: Detector Design Parameters


Decay Modes

Sensitivity to a variety of decay modes removes dependence on model predictions.

1X b For example, for hybrids: favored

not-favoredX

Measure many decay modes!

To certify results, checks will be made among different final states for the same decay mode, for example:

b1 0 3

0 2

Should givesame results


Tracking Requirements

pmm p

For simple kinematicsFor the narrow resonance

~1%M

E + 1%E/E ~ 5%/√p/p ~ 2%, ~ 2 mrad

Charged particles Photons

In order to maximize signal to background and at the same time balance the contributions from photons and charged particles, we have set the following goals:

x ~ 5mm/√E


Illustrative example

Perfect tracking

Perfect calorimetry

nominal

Charged tracking resolution is dominated by multiple scattering

Charged tracking matched to calorimetry

Generate zero-width


Position resolution

Momentum resolution of ~2% requires

→ Material budget < 5% rad. length

→ Position uncertainties of < 150-200 m to remain small relative to the multiple scattering contribution.

Require CDC < 150 m

Momentum resolution at 900

p/

p

Require FDC < 200 m


Angular coverage in c.m.

Require coverage down to 1o in the laboratory

Cos GJ for X→

lab > 1o lab > 2oGenerated

X


Detector Elevation View

125o

11o

1o

25o


Forward Region FDC 4 packages of planar drift chambers anode + cathode strip readout six planes per package xy=200m active close to the beam line.

Central Region CDC cylindrical straw-tube chamber 25 layers from 10cm to 57cm ±6o stereo layers r=150m z = 2mm dE/dx for p < 450 MeV/c

Tracking


Detector Plan View

cryogeniclines

electronic racks

Central panel480 AC 3 phase

beam

solenoid Fcal

Cerenkov

Staging Area

door

overheadcrane

(two levels)

(two levels)

Hall D layout showing approximate location of readout electronics crates, and power distribution.


Tools used to evaluate design choices

Generated Physics Events

“Raw” Monte Carlo Data

Model of Detector

Reconstruction package

Partial Wave Analysis

Reconstructed Monte Carlo Data

Event Generator

GEANT3

Parametric Monte Carlo

HDFast

Complete model for CD-2• background rates

original model

Track finding and momentum fitting• hardware design

Photon reconstruction under development

parametric reconstruction

PWA studiesUnder development


Simulation and reconstruction

Momentum reconstruction applied to full GEANT simulation of event, smeared DC hits, no background. The GEANT simulation event and reconstruction software and are being used to understand detector performance (see next talk).


Models of detector performance

Parametric Monte Carlo 2004

Momentum Reconstruction

2007


Today’s Presentations

6. Reconstruction and prototyping (FDC) Simon Taylor

1. Overview

Simulation and reconstruction

4. Central Drift Chamber Curtis Meyer

5. Electronics Fernando Barbosa

3. Forward Drift Chamber Daniel Carman

2. Tracking and simulation David Lawrence

On-chamber electronics


Summary Mapping the spectrum of hybrid mesons provides essential experimental data on the physics of the strong interactions in the region of confinement and is one of the main physics motivations for the 12 GeV Project.

This program requires

Momentum resolution of ~ 2%

Angular resolution of ~ 2 mrad

Material thickness < 5% rad. length

(FDC) < 200 m

(CDC) < 150 m

Today you are asked to review the design of the Hall D drift chambers for use in this experimental program.

Documents

Drift Chamber Review March 6-8, 2007 1 Overview of Requirements Forward and Central Drift Chambers Elton S. Smith Jefferson Lab Physics goals Overview