The Liquid Argon Time Projection Chamber (LAr TPC) in Neutrino Physics Bruce Baller Fermilab 1 SLAC Instrumenta0on Seminar ‐ Feb 10, 2010
The Liquid Argon Time Projection
Chamber (LAr TPC) in Neutrino
Physics Bruce Baller
Fermilab
1SLACInstrumenta0onSeminar‐Feb10,
2010
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
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2010
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fromMitchSoderberg
ppm in air 0 12 1 9500 0.1
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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
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ICARUSpioneerinLArTPCtechnologyTheU.S.LArTPCprogramusesICARUSasafounda0on
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ICARUS T600
1.5m 1.5m
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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
e.m. shower
µ decay
stopping µ with decay electron
hadron cascade
nuclear interaction
e.m. showers
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LeadingtoLAr20
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Fermilab
DUSEL
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
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Isthistechnologyready?Isitcostcompe00ve,safe?
17m
~3m
19m
LAr20Concepts
• 300’/4850’underground
• Membrane/modularcryostat– ~20,000m3
• TPCconfigura0on• Lightcollec0onforsupernova&protondecay
• FNALbeamtrigger
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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
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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
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Expensivecryostat
Expensiveforalargecryostat
Isthisneeded?FNALR&DMaterialsTestStand
ICARUSPurifica0onExperience
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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
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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)
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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
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Test Stands (Bo & Luke)
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Stephen Pordes (FNAL)
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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
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Materials Test Run
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Cold pre-amp
Cables & Cable ties
T962DecouplingBoard
Summary of Results
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Water Effects - 1
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FR-4 based circuit board – from Argonlock with evacuation
Little change in H20 reading and little change in lifetime
Water Effects - 2
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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
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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
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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
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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
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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
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u
v y
U
V
Y
2 6 4 Time (µs)
Dri
ft D
ista
nce
(cm
) Charge Signal Formation
Current Out of Wire
Induction (small, bipolar)
Induction (small, bipolar)
Collection (large, unipolar)
Induction by and
Collection of electrons on
wires
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u
v
y
Inclined Tracks
Waveform shape varies with the inclination angle
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Noise vs T in CMOS: Preliminary Test Result Exis)ngASIC,notdesignedforLAr
T[K]
ENC[erms]
CMOS in LAr has less than half the noise as that at room temperature
ENCvs.T(Cd=100pF,0.5µspeaking0me)
LAr87K
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• 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.
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• 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)
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D0 spares 6% overshoot in ArgoNeut
Edmunds (Michigan State)
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Induction Plane
Collection Plane
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Collection Plane
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Largeenergydeposi0onlargeovershoot
Induc0onPlane
Collec0onPlane
Waveform Deconvolution
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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
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Overshoot different for different shaper cards
Collec0onPlane
Deconvolution Results Very Preliminary
Collec0onPlane
A Deconvolution Trick
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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
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Run 561 Event 220 Induction Plane Channel
Raw Data
Std deconvolution kernel
Deconvolute w Trick kernel (needs filter tuning)
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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
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BackupSlides
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ArgoNeut Purity History
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ENC vs Sense Wire resistanceSSsensewire150µm(36ohm/m)andCu+AuplatedSSwire(3ohm/m)
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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.
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• 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:
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Signalfor
(1/edri0)
3x35x5
104e
Signalfor
(1/edri0)
3x35x5
104e
Noise vs Sense Wire and Cable Length
Warm Electronics
On-wire Electronics Small TPC
BigTPC
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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
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100%efficiencyin2tracksepara0onforsep>4mmArgoNeutsimula0on