The Liquid Argon Time Projection Chamber (LAr TPC) in ...

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The Liquid Argon Time Projection

Chamber (LAr TPC) in Neutrino

Physics Bruce Baller

Fermilab

1SLACInstrumenta0onSeminar‐Feb10,

Outline

•  LAr TPC basics •  History •  ICARUS •  Long Baseline Neutrino Experiment (LBNE) •  R&D in the U.S.

– Argon purity – On-wire electronics – LAr TPC operation

•  Summary

2SLACInstrumenta0onSeminar‐Feb10,

SLACInstrumenta0onSeminar‐Feb10,2010 3

fromMitchSoderberg

ppm in air 0 12 1 9500 0.1

NeedextremelygoodLArpurity,lowconvec0veflow

2.5m1.6ms

History •  1968 - Alvarez proposed the use of liquefied

noble gases as detector media •  1970’s

–  LAr & LXe calorimeters in use, LAr TPC prototypes

– Willis, Chen, Radeka, Gatti, Rubbia contributions

•  1977 – Carlo Rubbia proposed the LAr TPC •  1985 – ICARUS (T600) proposal at Gran Sasso

–  1993 – Cosmic rays tracked with a 3 ton LAr TPC

5SLACInstrumenta0onSeminar‐Feb10,2010

ICARUSpioneerinLArTPCtechnologyTheU.S.LArTPCprogramusesICARUSasafounda0on

ICARUS T600

1.5m 1.5m

2007-2010 Activities – ICARUS Collaboration

The preparation of ICARUS has been completed The vacuum pump-down in progress. At 10-4 Torr LAr filling planned for Feb 28 – mid March

CNGS run starts in April – 6 months (~1k events?)

Picturescircalate2009

CourtesyofD.Cline

T600 surface test in Pavia - 2001

e.m. shower

µ decay

stopping µ with decay electron

hadron cascade

nuclear interaction

e.m. showers

CourtesyofD.Cline 8SLACInstrumenta0onSeminar‐Feb10,2010

LeadingtoLAr20

Fermilab

LBNE - Long Baseline Neutrino Experiment $900M on 1 slide

•  10 year project •  CD-0 granted in mid January •  CD-0 Scope

–  700kW proton beam (upgrade path to 2MW) –  Neutrino beam (0.5 – 4 GeV) –  Near detector –  1000+km baseline –  2 x 100kton Water Cherenkov Equivalent far

detectors, for instance •  100kton WC •  16.7 kton LAr TPC LAr20

•  CD-1 review December 2010

Isthistechnologyready?Isitcostcompe00ve,safe?

LAr20Concepts

•  300’/4850’underground

•  Membrane/modularcryostat–  ~20,000m3

•  TPCconfigura0on•  Lightcollec0onforsupernova&protondecay

•  FNALbeamtrigger

Main Challenges for Massive LAr TPCs

  LAr Purity in large industrial vessels   Materials qualification: test stand measurements   Purification techniques for non-evacuable vessels

  Large scale low noise readout (~500k channels)   On-Wire (cold) electronics and signal multiplexing   Test stands

  Underground issues: safety, installation   Cost

ICARUS Purification Steps •  Use high vacuum standards in construction and

cleaning •  Evacuate the cryostat to < 10-3 mbar to remove

contaminants •  Cool quickly and fill with LAr to minimize

outgassing •  Re-liquefy gaseous argon (GAr) boil-off and

purify before returning to the main volume •  Recirculate and purify the main LAr volume if

there is significant contamination at filling or due to an upset condition

Expensivecryostat

Expensiveforalargecryostat

Isthisneeded?FNALR&DMaterialsTestStand

ICARUSPurifica0onExperience

1.5xtheICARUSdri[0me

Purity Requirement •  Electro-negative

contaminants –  O2 & water

•  If 20% signal loss is OK for 2m drift –  Need 5 ms electron

lifetime ~60 ppt O2 contamination

–  LAr supply typical 1 ppm

•  N2 < 1 ppm for light collection

SLAC Instrumentation Seminar - Feb 10, 2010 17

Purification Methods & Instrumentation

•  Three stage – Molecular sieve removes water – Copper removes oxygen – Active carbon removes hydrocarbons – In-place regeneration

•  Commercial in-line instrumentation – 300ppt sensitivity

•  In-line purity monitor (ICARUS)

PrMscopesignal PrMautoma0onso[ware

PurityMonitor–Dri[Cell

Materials Qualification

•  No published results on materials effects on electron lifetime from ICARUS or other exps – Materials Test Stand

•  ICARUS experience: detector materials outgas contaminants despite the care taken in construction and evacuation – Materials Test Stand

Test Stands (Bo & Luke)

Stephen Pordes (FNAL)

Pordes,Kendziora,Tope(FNAL)

Materials Test Stand Features •  Can insert materials into known clean argon •  Can insert materials after purging only or after

pumping on them. •  Can position materials into liquid and into ullage

with range of temperatures •  Can insert known amounts of contaminant gases •  LN2 condenser can maintain liquid for long

studies (weeks) •  Internal filter-pump can remove contamination

introduced by materials – 2hr cycle •  Sample points at Argon Source, after single-pass

filters, in cryostat gas and liquid

Materials Test Run

Cold pre-amp

Cables & Cable ties

T962DecouplingBoard

Summary of Results

Water Effects - 1

FR-4 based circuit board – from Argonlock with evacuation

Little change in H20 reading and little change in lifetime

Water Effects - 2

FR-4 based circuit board – from Argonlock with purging only

Significant change in H20 reading and significant reduction in lifetime

Water is the dominant contaminant, not O2, for lifetimes of 5 – 10 msec Not a contaminant if the materials containing it are maintained at ~100K

Purification in a Massive LAr TPC

•  Contaminants are in the vapor – Remove gas from top of cryostat continuously

•  Removal rate proportional to the partial pressure difference of the water concentration in materials and the surrounding atmosphere – Hot dry argon gas should be as effective as

evacuation in removing water (and O2) •  Liquid Argon Purity Demonstrator (LAPD) will

test this concept

LAPD •  Commercial SS tank &

cryo system •  Steps

–  Remove air w gaseous argon (GAr) piston

–  Flush w GAr •  2.6 volumes 100 ppm

–  Heat to 50oC –  Recirculate GAr through

purification system –  Cool-down and fill w LAr –  Check purity

•  Results in Fall 2010

10 feet

Brian Rebel, Rob Plunkett (FNAL)

LAr20 Membrane Cryostat Option

•  Attractive if evacuation is not necessary –  Efficient use of the excavated cavern volume –  Design used in LNG tankers of volume 10x LAr20 –  240 tankers in service

On-Wire Electronics •  Large detector (20m x 20m) long cables to

preamplifiers high noise on-wire electronics –  Identify a CMOS process suitable for cryogenic

operation that will be available in 5 years •  Work by Radeka, Rescia (BNL), Yarema, Deptuch

(FNAL), Edmunds (MSU) –  New collaboration with Cressler (Georgia Tech)

•  Other activity not in this talk –  Marvin Johnson (FNAL) exploring the limits of

warm readout electronics with low capacitance woven cable

Signal cable lengths increasing to >10-20 meters for detector fiducial volume > 1kton resulting in high capacitance and high noise

Cold electronics decouples the electrode and cryostat design from the readout design: noise independent of the fiducial volume

Cryostat Design: “Warm” vs “On-Wire” Electronics

CablesoutgasinwarmGAr

2 6 4 Time (µs)

) Charge Signal Formation

Current Out of Wire

Induction (small, bipolar)

Collection (large, unipolar)

Induction by and

Collection of electrons on

Inclined Tracks

Waveform shape varies with the inclination angle

Noise vs T in CMOS: Preliminary Test Result Exis)ngASIC,notdesignedforLAr

ENC[erms]

CMOS in LAr has less than half the noise as that at room temperature

ENCvs.T(Cd=100pF,0.5µspeaking0me)

LAr87K

• Degrada'onisduetoimpactioniza'on

• chargetrapinoxide,interfacegenera0on→shi[inVthandgm

• Substratecurrentisamonitorofimpactioniza'on

• increaseswithdrainvoltage• ishigherinshortchanneldevices• hasamaximumatVgs≈Vds/2

• increasesasthetemperaturedecreases

CMOS Reliability at Cryogenic Temperatures – Basic Mechanism

• Commercialtechnologiesarerated10yearslife0me(10%shi[)inworstcasecon0nuousopera0on:T=220K,L=Lmin,Vds=nominalVdd,Vgs≈Vds/2)

• AcceleratedtestsatincreasedVdsallowextrapola'onoflife'me J.Cressleretal.

•  Reliabilityatlowtemperaturecanbeguaranteedby:

1.  decreasingVds(i.e.decreasingthesupplyvoltage)

2.  decreasingVgs(i.e.decreasingthedraincurrentdensity)

3.  increasingL(i.e.non‐minimumchannellengthdevices)

•  Designguidelines:

1.analogcircuits

•  operatedevicesatlowcurrentdensity

•  usenon‐minimumchannellengthL

2.digitalcircuits

•  operatedevicesat2/3ofnom.Vdd

•  usenon‐minimumchannellengthL

CMOS Reliability at Cryogenic Temperatures – Design Guidelines

J.Cressleretal.Accelerated tests will be performed to guarantee > 20 yr lifetime at 90 K (operated at Vdd and max. current continuously)

D0 spares 6% overshoot in ArgoNeut

Edmunds (Michigan State)

Induction Plane

Collection Plane

Largeenergydeposi0onlargeovershoot

Induc0onPlane

Collec0onPlane

Waveform Deconvolution

ADCShaperOut=WireSignal⊗Preamp⊗Shaper

Convolu0on

ADC=F‐1{(F(WireSignal)*F(Preamp)*F(Shaper)}

FourierTransform

De‐convolu0on

WireSignal=F‐1{Filter*F(ADC)/(F(Preamp)*F(Shaper))}

Remove electronics effects Band filter to remove coherent noise, etc

Not needed with careful electronics design

Overshoot different for different shaper cards

Collec0onPlane

Deconvolution Results Very Preliminary

Collec0onPlane

A Deconvolution Trick

Convert bi-polar induction plane waveform to uni-polar collection plane waveform Only one hit reconstruction algorithm needed!

WireSignal=F‐1{Filter*F(ADC)*F(Col) (F(Preamp)*F(Shaper)*F(Ind))}

Collec0on(Induc0on)planewaveform1MIPresponse

Run 561 Event 220 Induction Plane Channel

Raw Data

Std deconvolution kernel

Deconvolute w Trick kernel (needs filter tuning)

Summary

•  Noble liquids: 40 years of R&D •  LAr TPC: 30 years of R&D •  ICARUS pioneered and mastered this

technology •  The U.S. is a recent immigrant in the field

– World class R&D contributions applicable to MicroBooNE, LAr20, GLACIER and potentially DM exps

•  On-going R&D will confirm the viability of this technology for LBNE in the next few years

BackupSlides

ArgoNeut Purity History

ENC vs Sense Wire resistanceSSsensewire150µm(36ohm/m)andCu+AuplatedSSwire(3ohm/m)

kT = e/Dm TTRAN = 480K TLONG = 200K

(2.5 m)

Diffusion, drift velocity, and the time scale of induced signals

•  The time scale of the detector signals is determined by the wire plane spacing and the electron drift velocity (~1.5 mm/µs at 500 V/cm).

•  Diffusion smoothes out the high frequency components due to the coarse sense wire grid structure which don’t include any useful information. Diffusion broadening of the signal ~ 0.6 µs rms.

•  A 3mm MIP track will deposit 210keV/mm x 3mm /23.6eV/e = 4.3fC

•  After a 1/3 initial recombination loss: ~2.8fC

•  It is expected that the TPC design will maximize the drift path to equal or exceed the charge life time, thereby reducing the signal to 1/e≈0.368

•  The expected signal for 3mm wire spacing is then ≈1fC=6250 electrons,

… and for 5mm, ≈104

electrons, for the collection signal •  The induction signals are smaller

Signals in LAr TPC

Induced Current Waveforms on 3 Sense Wire Planes:

Charge signal:

Signalfor

(1/edri0)

3x35x5

Signalfor

(1/edri0)

3x35x5

Noise vs Sense Wire and Cable Length

Warm Electronics

On-wire Electronics Small TPC

BigTPC

A Functional Outline of a Multiplexed Readout Chain for Very Large LAr TPCs

A Functional Outline of a Multiplexed Readout Chain for Very Large LAr TPCs. Multiplexing will be performed in two steps at appropriate locations within the cryostat. A CMOS, or a BiCMOS technology with circuit design and operating conditions for long term operation in LAr will be used. A preliminary goal is multiplexing in two steps by 16 x 8=128. Power dissipation has been estimated to be ≤10mW/signal wire.

Hit Shape Fitting Two Track Separation- MC

100%efficiencyin2tracksepara0onforsep>4mmArgoNeutsimula0on

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