The Liquid Argon Time Projection Chamber (LAr TPC) in Neutrino Physics. Bruce Baller Fermilab

Transcription

1 The Liquid Argon Time Projection Chamber (LAr TPC) in Neutrino Physics Bruce Baller Fermilab 1

2 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 2

3 from Mitch Soderberg ppm in air

4 2.5m 1.6ms Need extremely good LAr purity, low convec0ve flow 4

5 History 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 ICARUS pioneer in LAr TPC technology The U.S. LAr TPC program uses ICARUS as a founda0on 5

6 ICARUS T m 1.5m 6

7 Activities ICARUS Collaboration Pictures circa late 2009 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?) Courtesy of D. Cline 7

8 T600 surface test in Pavia stopping µ with decay electron hadron cascade nuclear interaction e.m. showers e.m. shower µ decay e.m. shower Courtesy of D. Cline 8

9 Leading to LAr20 9

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11 DUSEL Fermilab SLAC Instrumenta0on Seminar Feb 10,

12 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 Is this technology ready? Is it cost compe00ve, safe? 12

13 LAr20 Concepts 300 /4850 underground Membrane/modular cryostat ~20,000m 3 TPC configura0on Light collec0on for supernova & proton decay FNAL beam trigger 17m ~3m 19m 13

14 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 14

15 ICARUS Purification Steps Use high vacuum standards in construction and cleaning Is this needed? FNAL R&D Materials Test Stand Evacuate the cryostat to < 10-3 mbar to remove contaminants Expensive cryostat Cool quickly and fill with LAr to minimize outgassing Expensive for a large cryostat 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 15

16 ICARUS Purifica0on Experience 1.5x the ICARUS dri[ 0me 16

17 Purity Requirement Electro-negative contaminants O 2 & water If 20% signal loss is OK for 2m drift Need 5 ms electron lifetime ~60 ppt O 2 contamination LAr supply typical 1 ppm N 2 < 1 ppm for light collection SLAC Instrumentation Seminar - Feb 10,

18 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) 18

19 Purity Monitor Dri[ Cell PrM scope signal PrM automa0on so[ware 19

20 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 20

21 Test Stands (Bo & Luke) SLAC Instrumentation Seminar - Feb 10, 2010 Stephen Pordes (FNAL) 21

22 Pordes, Kendziora, Tope (FNAL) 22

23 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 SLAC Instrumentation Seminar - Feb 10,

24 Materials Test Run Cables & Cable ties T962DecouplingBoard Cold pre-amp SLAC Instrumentation Seminar - Feb 10,

25 Summary of Results SLAC Instrumentation Seminar - Feb 10,

26 Water Effects - 1 FR-4 based circuit board from Argonlock with evacuation Little change in H20 reading and little change in lifetime SLAC Instrumentation Seminar - Feb 10,

27 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 O 2, for lifetimes of 5 10 msec Not a contaminant if the materials containing it are maintained at ~100K SLAC Instrumentation Seminar - Feb 10,

28 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 O 2 ) Liquid Argon Purity Demonstrator (LAPD) will test this concept 28

29 LAPD Commercial SS tank & cryo system Steps Remove air w gaseous argon (GAr) piston Flush w GAr 2.6 volumes 100 ppm Heat to 50 o C Recirculate GAr through purification system Cool-down and fill w LAr Check purity Results in Fall 2010 Brian Rebel, Rob Plunkett (FNAL) 10 feet SLAC Instrumentation Seminar - Feb 10,

30 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 LAr tankers in service 30

31 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 31

32 Cryostat Design: Warm vs On-Wire Electronics Cables outgas in warm GAr 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 32

33 Charge Signal Formation Drift Distance (cm) Time (µs) Current Out of Wire Induction by and Collection of SLAC Instrumentation Seminar - Feb 10, u v y electrons on wires U V Y Induction (small, bipolar) Induction (small, bipolar) Collection (large, unipolar) 33

34 Inclined Tracks Waveform shape varies with the inclination angle u v y 34

35 Noise vs T in CMOS: Preliminary Test Result Exis)ng ASIC, not designed for LAr ENC vs. T (Cd=100pF, 0.5µs peaking 0me) ENC [e rms] LAr 87K T [K] CMOS in LAr has less than half the noise as that at room temperature 35

36 CMOS Reliability at Cryogenic Temperatures Basic Mechanism Degrada'on is due to impact ioniza'on charge trap in oxide, interface genera0on shi[ in V th and g m Substrate current is a monitor of impact ioniza'on increases with drain voltage is higher in short channel devices has a maximum at V gs V ds /2 increases as the temperature decreases Commercial technologies are rated 10 years life0me (10% shi[) in worst case con0nuous opera0on: T = 220 K, L = L min, V ds = nominal V dd, V gs V ds /2) J. Cressler et al. Accelerated tests at increased Vds allow extrapola'on of life'me 36

37 CMOS Reliability at Cryogenic Temperatures Design Guidelines Reliability at low temperature can be guaranteed by: 1. decreasing Vds (i.e. decreasing the supply voltage) 2. decreasing Vgs (i.e. decreasing the drain current density) 3. increasing L (i.e. non minimum channel length devices) Design guidelines: 1. analog circuits operate devices at low current density use non minimum channel length L 2. digital circuits operate devices at 2/3 of nom. Vdd use non minimum channel length L J. Cressler et al. Accelerated tests will be performed to guarantee > 20 yr lifetime at 90 K (operated at Vdd and max. current continuously) 37

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40 Edmunds (Michigan State) D0 spares 6% overshoot in ArgoNeut 40

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42 Induction Plane Collection Plane 42

43 Collection Plane 43

44 Induc0on Plane Collec0on Plane Large energy deposi0on large overshoot 44

45 Waveform Deconvolution Convolu0on ADC Shaper Out = Wire Signal Preamp Shaper ADC = F 1 { (F(Wire Signal) * F(Preamp) * F(Shaper) } De convolu0on Fourier Transform Wire Signal = F 1 { Filter *F(ADC) / (F(Preamp) * F(Shaper) ) } Band filter to remove coherent noise, etc Remove electronics effects Not needed with careful electronics design 45

46 Deconvolution Results Very Preliminary Collec0on Plane Overshoot different for different shaper cards Collec0on Plane 46

47 A Deconvolution Trick Convert bi-polar induction plane waveform to uni-polar collection plane waveform Only one hit reconstruction algorithm needed! Wire Signal = F 1 { Filter *F(ADC) * F(Col) (F(Preamp) * F(Shaper) * F(Ind) ) } Collec0on (Induc0on) plane waveform 1 MIP response 47

48 Run 561 Event 220 Induction Plane Channel Raw Data Std deconvolution kernel Deconvolute w Trick kernel (needs filter tuning) 48

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50 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 50

51 Backup Slides 51

52 ArgoNeut Purity History 52

53 ENC vs Sense Wire resistance SS sense wire 150µm (36ohm/m) and Cu+Au plated SS wire (3 ohm/m) 53

54 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. (2.5 m) kt = e/dm T TRAN = 480K T LONG = 200K SLAC Instrumentation Seminar - Feb 10,

55 Signals in LAr TPC Charge signal: 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 The expected signal for 3mm wire spacing is then 1fC=6250 electrons, and for 5mm, 10 4 electrons, for the collection signal The induction signals are smaller Induced Current Waveforms on 3 Sense Wire Planes: SLAC Instrumentation Seminar - Feb 10,

56 Noise vs Sense Wire and Cable Length 10 4 e Signal for (1/e dri0) 3x3 5x5 BigTPC Warm Electronics Small TPC On-wire Electronics 56

57 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. 57

58 Hit Shape Fitting Two Track Separation- MC 100% efficiency in 2 track separa0on for sep > 4 mm ArgoNeut simula0on 58