Document 7198795

Transcript Document 7198795

André Rubbia - November 2003

André Rubbia, ETH Zürich (ICARUS Collaboration) Paris meeting, November 2003 Simulations performed by Paola Sala (ETHZ+ INFN )

   

Introduction

The liquid Argon TPC technology is a new kind of detector, effectively an electronic bubble-chamber , originally proposed at CERN by Carlo Rubbia (CERN-EP/77-08 (1977)) and supported by Italian INFN over many years of R&D It has recently regained a strong interest in the community, after the 1. The successful assembly and operation of the ICARUS T600 that demonstrated that the technology is mature 2. The realization of the imaging and extremely high resolution, in the context of  enormous Underground physics physics potential offered by high granularity (proton decay, solar, supernova, …)  Short-baseline (now called “near detectors”) low/medium cross-sections or high-energy precision neutrino physics  Long-baseline neutrino physics (superbeams and/or NF) As a consequence, preprints, proceedings, LOI’s, etc… have recently appeared concerning liquid argon detectors, from the smallest (≈10-100 tons) to the biggest (>100 ktons) sizes, with varying level of credibility.

Currently, we can state safely:   ICARUS T3000 at the Gran Sasso Laboratory is so far the most important milestone for this technology and acts as a full-scale test-bed with a total of 3 kton of liquid Argon to be located in a difficult underground environment.

The possible extrapolation to giant liquid argon detector investigated. This is the subject of this talk.

(≈100kton) must be André Rubbia - November 2003 2

The ICARUS collaboration (25 institutes, ≈150 physicists)

M. Aguilar-Benitez, S. Amoruso, Yu. Andreew, P. Aprili, F. Arneodo, B. Babussinov, B. Badelek, A. Badertscher, M.

Baldo-Ceolin, G. Battistoni, B. Bekman, P. Benetti, E. Bernardini, A. Borio di Tigliole, M. Bischofberger, R. Brunetti, R.

Bruzzese, A. Bueno, C. Burgos, E. Calligarich, D. Cavalli, F. Cavanna, F. Carbonara, P. Cennini, S. Centro, M.

Cerrada, A. Cesana, R. Chandrasekharan, C. Chen, D. B. Chen, Y. Chen, R. Cid, D. Cline, P. Crivelli, A.G. Cocco, A.

Dabrowska, Z. Dai, M. Daniel, M. Daszkiewicz, C. De Vecchi, A. Di Cicco, R. Dolfini, A. Ereditato, M. Felcini, A. Ferrari, F. Ferri, G. Fiorillo, M.C. Fouz, S. Galli, D. Garcia, Y. Ge, D. Gibin, A. Gigli Berzolari, I. Gil-Botella, S.N. Gninenko, N.

Goloubev, A. Guglielmi, K. Graczyk, L. Grandi, K. He, J. Holeczek, X. Huang, C. Juszczak, D. Kielczewska, M.

Kirsanov, J. Kisiel, L. Knecht, T. Kozlowski, H. Kuna-Ciskal, N. Krasnikov, P. Ladron de Guevara, M. Laffranchi, J.

Lagoda, Z. Li, B. Lisowski, F. Lu, J. Ma, N. Makrouchina, G. Mangano, G. Mannocchi, M. Markiewicz, A. Martinez de la Osa, V. Matveev, C. Matthey, F. Mauri, D. Mazza, A. Melgarejo, G. Meng, A. Meregaglia, M. Messina, C. Montanari, S.

Muraro, G. Natterer, S. Navas-Concha, M. Nicoletto, G. Nurzia, C. Osuna, S. Otwinowski, Q. Ouyang, O. Palamara, D.

Pascoli, L. Periale, G. Piano Mortari, A. Piazzoli, P. Picchi, F. Pietropaolo, W. Polchlopek, T. Rancati, A. Rappoldi, G.L.

Raselli, J. Rico, L. Romero, E. Rondio, M. Rossella, A. Rubbia, C. Rubbia, P. Sala, N. Santorelli, D. Scannicchio, E.

Segreto, Y. Seo, F. Sergiampietri, J. Sobczyk, N. Spinelli, J. Stepaniak, M. Stodulski, M. Szarska, M. Szeptycka, M.

Szeleper, M. Terrani, R. Velotta, S. Ventura, C. Vignoli, H. Wang, X. Wang, C. Willmott, M. Wojcik, J. Woo, G. Xu, Z.

Xu, X. Yang, A. Zalewska, J. Zalipska, C. Zhang, Q. Zhang, S. Zhen, W. Zipper.

ITALY

: L'Aquila, LNF, LNGS, Milano, Napoli, Padova, Pavia, Pisa, CNR Torino, Torino Univ., Politec. Milano.

SWITZERLAND

: ETH/Zürich.

CHINA

: Academia Sinica Beijing.

POLAND

: Univ. of Silesia Katowice, Univ. of Mining and Metallurgy Krakow, Inst. of Nucl. Phys. Krakow, Jagellonian Univ. Krakow, Univ. of Technology Krakow, A.Soltan Inst. for Nucl. Studies Warszawa, Warsaw Univ., Wroclaw Univ.

USA

: UCLA Los Angeles.

SPAIN

: Univ. of Granada, CIEMAT

RUSSIA

: INR (Moscow) André Rubbia - November 2003 3

ICARUS T3000: “A Second-Generation Proton Decay Experiment and Neutrino Observatory at the Gran Sasso Laboratory”

André Rubbia - November 2003 n K 4

André Rubbia - November 2003

ICARUS R&D - 50 liter prototype in CERN West Area neutrino beam

n  

   

25 cm

ICARUS T600: cosmic rays on surface

Shower

85 cm 434 cm 265 cm

Muon decay

Run 960, Event 4 Collection Left André Rubbia - November 2003

Hadronic interaction

Run 308, Event 160 Collection Left 142 cm 6

ICARUS T300 cryostat (1 out of 2)

André Rubbia - November 2003 7

Cryostat (half-module)

4 m 20 m 4 m

Readout electronics

ICARUS T300 prototype

View of the inner detector André Rubbia - November 2003 8



Liquefied rare gases TPC: basic ideas

Ideal materials for detection of ionizing tracks:   Dense (≈g/cm 3 ≈ 10 3 x r gas ), homogeneous, target and detector Do not attach electrons (  long drift paths possible in liquid phase)  High electron mobility (≈quasi-free drift electrons, not neon)   Commercially easy to obtain (in particular, liquid Argon) Can be made very pure and many impurities freeze out at low temperature  Inert, not flammable Type Neon Argon Krypton Xenon Density ( r /cm 3 ) 1.2

1.4

2.4

3.0

Energy loss dE/dx (MeV/cm) 1.4

2.1

3.0

3.8

Radiation length X 0 (cm) 24 14 4.9

2.8

Collision length l (cm) 80 80 29 34 Boiling point @ 1 bar (K) 27.1

87.3

Electron mobility (cm 2 /Vs) high&low 500 120 165 1200 2200 € €€ €€€ André Rubbia - November 2003 9

Processes induced by charged particles in dense rare gases

When a charged particle traverses medium:

   Ionization process Scintillation (luminescence)  UV spectrum  Not energetic enough to further ionize, hence, medium is transparent  Rayleigh-scattering Cerenkov light (if fast particle)

UV light Charge Cerenkov light (if

>1/n)

M. Suzuki et al., NIM 192 (1982) 565 André Rubbia - November 2003 10

I Density dE/dx W e-ion W g Scintillation photons/MeV Decay const

Scintillation peak Rayleigh scattering length for scintillation

nm cm

André Rubbia - November 2003

g/cm 3 MeV/cm eV eV eV photons

Comparison rare gases

LAr 1.39

2.11

15.76

23.6

±0.3

19.5

≈50000 LKr

2.45

3.45

14.00

20.5

±1.5

52 ≈19000

6(23%), 1600(77%) 128 ≈90 LXe

3.06

3.89

12.13

16.4

±1.4

38 ≈26000 2(1%),85(99%) 2(77%),30(33%) 147 ≈60 174 ≈30 11

Comparison water - liquid Argon

Density (g/cm 3 ) Radiation length (cm) Interaction length (cm) dE/dx (MeV/cm) Refractive index (visible) Cerenkov angle Cerenkov d 2 N/dEdx ( b =1) Muon Cerenkov threshold (p in MeV/c) Scintillation Cost André Rubbia - November 2003 Water 1 36.1

83.6

1.9

1.33

42 ° ≈160 eV  1 cm  1 120 No 1 CHF/liter (Evian) Liquid Argon 1.4

14.0

83.6

2.1

1.24

36 ° ≈130 eV  1 cm  1 140 Yes (≈50000 g /MeV @ l =128nm) ≈1 CHF/liter 12

Comparison Water - liquid Argon

André Rubbia - November 2003

A “new way” to look at rare events…

André Rubbia - November 2003

Electron drift properties in liquid Argon

3 m 14

The Liquid Argon TPC (I)

UV Scintillation Light: L Readout planes: Q

Time

Low noise Q-amplifier

André Rubbia - November 2003 E drift Drift direction

Continuous waveform recording

•High density •Non-destructive readout •Continuously sensitive •Self-triggering •Huge scintillation: T 0 15

The Liquid Argon TPC (II)

    Cryogenics : Detector must be maintained at cryogenic temperatures, safety issues must be addressed for large detectors, in particular underground LAr Purity : Ionization tracks can be transported practically undistorted, by a uniform electric field, for distances of the order of several meters in a highly purified (electronegative impurities < 0.1 ppb O 2 equiv.) liquid argon (LAr).

Charge Readout : A set of electrodes (wires) placed at the end of the drift path senses the ionization charges and provides a two-dimensional view of the event (wire co-ordinate vs drift co-ordinate)  No charge multiplication occurs in LAr  several wire planes can be installed with the wires having different orientations  non-destructive charge readout  multiple views  3D reconstruction UV light Readout : LAr is also a very good scintillator  scintillation light ( l = 128 nm) provides a prompt signal to be used for triggering purposes and for absolute event time measurement  immersed pmt coated with WLS André Rubbia - November 2003 16

The need for 100 kton non-magnetized liquid Argon detectors

   Short baseline (now called “near detectors”) low/medium cross sections or high-energy precision neutrino physics  10-150 ton MAYBE magnetized B=0.5-1T Long-baseline neutrino physics  Superbeams   10 kton not necessarily magnetized (Phase I)  100 kton not necessarily magnetized (Phase II) b -beams  100 kton not magnetized  NF  10-20 kton magnetized B=1 T Underground physics (proton decay, supernova, atm, solar, …)  100 kton non magnetized

Different optimizations for different kinds of physics (Mini, medium, large, XL)

André Rubbia - November 2003 17

    

Extrapolation to underground kton liquid Argon TPCs: general considerations

The ICARUS collaboration has proposed an underground modular T3000 detector for LNGS based on the cloning of the T600  T3000 = T600 + T1200 + T1200  Design fully proven by t600 technical run  Ready to be built by industry The cost can be precisely estimated on the basis of the T600 prototype already built and is supported by actual offers  ≈20M$ per kton A 10 kton modular liquid argon detector could be ordered

today

cost ≈200 M$ (conservative)  This would be ok for superbeams (e.g. offaxis) and would Following a successful scaling up strategy, one could optimize costs and envision building bigger supermodules by increasing the dimensions of the current T1200 by a factor two in each directions:   

1200 

André Rubbia - November 2003 18

The ICARUS T1200 “Unit”

Detailed engineering project was produced by Air Liquide (June 2003) T1200 cryostat ready for tendering

André Rubbia - November 2003  Based on cloning the present T600 containers  A cost-effective solution given tunnel access conditions  Preassembled modules outside tunnel are arranged in supermodules of about 1200 ton each (4 containers)  Time effective solution (parallelizable)  Drift doubled 1.5 m  3 m  sensible solution given past experience  Built with large industrial support (AirLiquide, Breme-Tecnica, Galli Morelli, CAEN, …)  “order as many as you need” solution 19

Extrapolation to underground kton liquid Argon TPCs: a different approach

   There seem to be counter-indications to a non-modular design (the facts of life!)     Underground installation (access) Independent operation of each module Technique (drift, purity, readout, HV,…) already proven at the kton scale Safety requirements (?) However, a single volume appears to be the most attractive solution  Since to reach the wanted mass of 100 kton requires nonetheless a large number of supermodules (10x10kton ≈ 100 kton)  Is a strong R&D program required to extrapolate the liquid argon TPC to the 100 kton scale (in a single step?) In the following, I will try to address the feasibility of a single volume 100 kton liquid argon detector  The gains might be worth the R&D efforts André Rubbia - November 2003 20

Basic features:

Charge imaging + scintillation + Cerenkov light readout for complete event information Charge amplification to allow for extremely long drifts Single 100 kton “boiling” cryogenic tanker with Argon refrigeration André Rubbia - November 2003 21

Electronic crates

100 kton liquid Argon detector

≈70 m h =20 m Perlite insulation

André Rubbia - November 2003 22

Front view

André Rubbia - November 2003 f

≈70 m

André Rubbia - November 2003

Access and highway tunnel

Access highway

André Rubbia - November 2003

Access tunnel and highway tunnel

Access

André Rubbia - November 2003

Detector and highway tunnel

Detector

Open detector

Gas Argon Liquid Argon

André Rubbia - November 2003 27

Dewar Argon storage Argon total volume Argon total mass Hydrostatic pressure at bottom Inner detector dimensions Electron drift in liquid Charge readout view Charge readout channels Readout electronics Scintillation light readout Visible light readout André Rubbia - November 2003

Summary parameters

f ≈70 m, height ≈ 20 m, passive perlite insulated, heat input ≈5W/m 2 Boiling argon, low pressure (<100 mbar overpressure) 73118 m 3 (height = 19 m), ratio area/volume≈15% 102365 tons ≈3 atm Disc f ≈70 m located in gas phase above liquid phase 20 m maximum drift, HV=2 MV for

=1KV/cm,

v d ≈2 mm/µs, max drift time ≈10 ms

2 independent perpendicular views, 3mm pitch, in gas phase (electron extraction) with charge amplification (typ. x100) ≈100000 100 “ICARUS-like” racks on top of dewar (1000 channels per crate) Yes (also for triggering), 1000 immersed 8“ PMT with WLS (TPB) Yes (Cerenkov light), 27000 immersed 8“ PMTs or 20% coverage, single photon counting capability 28

André Rubbia - November 2003 29



Charge readout

Detector is running in  bi-phase mode In order to allow for long drift (≈20 m), we consider charge attenuation along drift and compensate this effect with charge amplification near anodes located in gas phase   Amplification operates in proportional mode After max drift of 20 m @ 1 KV/cm, diffusion ≈ readout pitch ≈ 3 mm Electron drift in liquid Charge readout view Maximum charge diffusion Maximum charge attenuation Needed charge amplification Methods for amplification Possible solutions André Rubbia - November 2003 20 m maximum drift, HV=2 MV for

=1KV/cm,

v d ≈2 mm/µs, max drift time ≈10 ms

2 independent perpendicular views, 3mm pitch s ≈2.8 mm (√2Dt max for D=4 cm 2 /s)



(

/ tmax) ≈ 1/150

for t =2 ms electron lifetime 10 2 to 10 3 Extraction to and amplification in gas phase Thin wires ( f ≈30  m)+pad readout, GEM, LEM, … 30

Electron extraction in Ar-biphase (ICARUS R&D)

Particle produces excitation (Ar*) and ionisation (Ar + , e) Scintillation SC is a result of: 1

Direct excitation 2

Recombination Electroluminescence EL (proportional scintillation) is a result of electron acceleration in the gas Electric Field GAr EL UV light LAr e Ar + SC UV light Both SC and EL can be detected by the same photodetector

André Rubbia - November 2003 31

   

Amplification near wires à la MWPC

Amplification in Ar 100% gas up to factor G≈100 is possible GARFIELD calculations in pure Ar 100%, T=87 K, p=1 atm Amplification near wires, signal dominated by ions Readout views: induced signal on (1) wires and (2) strips provide two perpendicular views Gain vs wire f @ 3.5kV

e

 Wire f =30  m

PCB with strips 10

2 André Rubbia - November 2003 32

Gas Electron Multiplier GEM (F. Sauli et al.)

QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture.

100x100 mm 2 A gas electron multiplier (GEM) consists of a thin, metal-clad polymer foil, chemically pierced by a high density of holes. On application of a difference of potential between the two electrodes, electrons released by radiation in the gas on one side of the structure drift into the holes, multiply and transfer to a collection region.

André Rubbia - November 2003 QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture.

GEM in dense rare gases (Buzulutskov et al.)

Buzulutskov et al, IEEE transaction on NS, e-print physics/0308010 Buzulutskov et al, NIMA513:256-259 (2003)

Gas phase Liquid phase

André Rubbia - November 2003 GEM GEM GEM 34

Large Electron Multiplier (LEM)

  A large scale GEM (x10) made with ultra-low radioactivity materials (OFHC copper plated on virgin Teflon)  In-house fabrication using automatic micromachining   Modest increase in V yields gain similar to GEM Self-supporting, easy to mount in multi-layers Extremely resistant to discharges (lower Capacitance)  Cu on PEEK under construction (zero out-gassing) Chicago-Purdue: P.S. Barbeau J.I

Shipsey Collar J. Miyamoto I.P.J. LEM bottom (anode) signal LEM top (cathode) signal André Rubbia - November 2003 35

LEM with Argon (ICARUS R&D)

Detection of charge signal and scintillation light produced during amplification

PRELIMINARY 400x400 mm 2

André Rubbia - November 2003

Holes

= 1 mm

André Rubbia - November 2003 37

UV light readout (ICARUS R&D)

•

Commercial PMT with large area



Glass-window

•

For scintillation VUV

l

= 128 nm



Wavelength-shifter

•

Immersed T(LAr) = 87 K

With TPB as WLS

Electron Tubes 9357FLA 8” PMT (bialkali with Pt deposit) G = 1 x 10 7 @ ~1400 V peak Q.E. (400 420 nm) ~ 18 % (≈10% cold) T rise ~ 5 ns, FWHM ~ 8 ns

André Rubbia - November 2003 Lally et al., NIMB 117 (1996) 421 38

Cerenkov light readout (ICARUS)

  M. Antonello et al., ICARUS Collab.,

"Detection of Cerenkov light emission in liquid Argon”

NIMA, Article in Press Immersed PMT 2” EMI-9814 BQ (sensitivity up to 160 nm) André Rubbia - November 2003

Data consistent with Cerenkov emission:

dN/dx(160-600nm) ≈ 700

/cm (

≈1)

André Rubbia - November 2003

We consider

: Phase 1: tanker filling Phase 2: running (refrigeration)

  

A dedicated cryogenic liquid plant for initial filling phase

Because of the large amount liquid argon needed to fill up the experiment (e.g. 300 ton/day to fill in 300 days), liquid argon must be produced locally One must envision a dedicated cryogenic plant located outside the tunnel connected to the detector via “km-long” vacuum-insulated pipes   Argon is extracted from the standard process of liquefaction from air Air mixture is cooled down and cold gas-mixtures are separated  Oxygen, Nitrogen, Argon, … and The Liquid Argon is used to fill the experiment. Liquid Oxygen and Liquid Nitrogen can be sold… André Rubbia - November 2003 41

Cryogenic parameters: initial filling phase

Liquid Argon 1st filling time Liquid Argon 1st filling rate Argon gas equivalent Air volume equivalent (Ar 1%) Ideal power of separation of Argon mixture Assumed efficiency Estimated power for Argon separation Ideal Argon liquefaction power Assumed efficiency Estimated Argon Liquefaction power Estimated total plant power 2 years (assumed) 1,2 liters/second or 150 tons/day 85000 m 3 /day 8’500’000 m 3 /day ≈ (205 m) 3 /day 600kW (assuming for Argon 354 kJ/kg) 5% 12 MW 817kW (assuming for Argon 478 kJ/kg) 5% 16 MW ≈30 MW André Rubbia - November 2003

Note: initial cooling of tanker not included

Ideal works for liquefaction and separation

Basic thermodynamics

R.F. Barron, Cryogenic Systems, 2nd edition 1985 (Oxford) André Rubbia - November 2003 43

Running phase (“refrigeration”)

    Filling the detector in two year has put a stringent constraint on the amount of LAr production rate needed During running phase, the detector will have to be refrigerated  This can be done in different ways, in particular, one could use LN is a priori cheaper than LAr 2  factory, what “evaporates”) since it However, taking advantage of the requirement of a local liquid argon we think that it would be much more advantageous to use Argon itself to refrigerate the detector (aka keep “filling” liquid Argon to replace It turns out that given the favorable area/volume ratio of the tanker/detector, the constraints from refrigeration are less than those from filling even assuming realistic non-vacuum insulated passive insulation !

The local cryogenic plant will therefore:  Continue to produce liquid Argon, a fraction will be needed for refrigeration, the surplus can be sold  Sell other products of liquefaction of air (LN 2 , …) André Rubbia - November 2003 44

The “dedicated” cryogenic complex

Electricity Air Hot GAr Underground complex GAr LAr Joule-Thompson expansion valve Heat exchanger Argon purification W Q

André Rubbia - November 2003

External complex LN 2 , …

Cryogenic parameters: boiling

Dewar Total area f ≈70 m, height ≈ 20 m, passive 3 m thick perlite insulated, assumed equivalent heat input ≈5 W/m 2 12100 m 2 Total heat input 60500 W Liquid Argon evaporation rate Fraction of total evaporation rate Time to totally empty tanker by evaporation 0.27 liters/second or 23000 liters/day 0.03% of total argon volume per day 9 years (!) Notes: •Heat loss should be conservative for 3 meter thick perlite and includes heat input from supports, instrumentation (cables), etc.) André Rubbia - November 2003 46

Thermal conductivities: gas-filled insulations

R.F. Barron, Cryogenic Systems, 2nd edition 1985 (Oxford)

Perlite: ≈8.8 W/m for T≈80K

André Rubbia - November 2003 47

Cryogenic parameters: refilling (refrigeration)

 The dedicated cryogenic plant must hence produce liquid argon to “refill” what has evaporated Liquid Argon refilling rate Argon gas equivalent Ideal Argon liquefaction power Assumed efficiency Estimated Argon Liquefaction power Air volume equivalent (Ar 1%) Ideal power of separation of Argon mixture Assumed efficiency Estimated power for Argon separation Estimated total power André Rubbia - November 2003 ≈0.3 liters/second or 23000 liters/day 0.2 m 3 /s or 200 l/s 180kW (assuming for Argon 478 kJ/kg) 5% 3.6 MW 20 m 3 /s or 20000 l/s 130kW (assuming for Argon 354 kJ/kg) 5% 2.6 MW 6.2 MW 48

LNG facts

  

WHAT IS IT?

When natural gas is cooled to a temperature of approximately -160 °C at atmospheric pressure it condenses to a liquid called liquefied natural gas (LNG ). One volume of this liquid takes up about 1/600th the volume of natural gas at a stove burner tip. When vaporized it burns only in concentrations of 5% to 15% when mixed with air.

COMPOSITION

Natural gas is composed primarily of methane (typically, at least 90%), but may also contain ethane, propane and heavier hydrocarbons.

HOW IS IT STORED?

low, less than 5 psig. LNG tanks are always of double-wall construction with extremely efficient insulation between the walls. Large tanks are low aspect ratio (height to width) and cylindrical in design with a domed roof. Storage pressures in these tanks are very 

HOW IS IT KEPT COLD?

"autorefrigeration". The insulation, as efficient as it is, will not keep the temperature of LNG cold by itself. LNG is stored as a "boiling cryogen," that is, it is a very cold liquid at its boiling point for the pressure it is being stored. LNG will stay at near constant temperature if kept at constant pressure. This phenomenon is called As long as the steam (LNG vapor boil off) is allowed to leave the tea kettle (tank), the temperature will remain constant . 

HAVE THERE BEEN ANY SERIOUS LNG ACCIDENTS?

First, one must remember that LNG is a form of energy and must be respected as such. Today LNG is transported and stored as safely as any other liquid fuel.

Before the storage of cryogenic liquids was fully understood, however, there was a serious incident involving LNG in Cleveland, Ohio in 1944 . This incident virtually stopped all development of the LNG industry for 20years. The race to the Moon led to a much better understanding of cryogenics and cryogenic storage with the expanded use of liquid hydrogen (-423 °F) and liquid oxygen (-296 °F). LNG technology grew from NASA's advancement .

André Rubbia - November 2003 49

André Rubbia - November 2003

Cryogenic storage tanks for LNG

Liquefaction of LNG and transport via ships

QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture.

Liquefaction plant in Oman e.g. Nigeria LNG (≈10 10 m 3 /year)

QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture.

Filled with LCH 4

Up to 145,000m 3

André Rubbia - November 2003 QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture.

André Rubbia - November 2003 52

André Rubbia - November 2003

Technodyne International Limited

Unit 16 Shakespeare Business Center Hathaway Close, Eastleigh, Hampshire, SO50 4SR 53

Contacts with Technodyne International Ltd

 

Query for an “Underground 70000 m3 Liquid Argon tanker” including design, safety and cost Answer:



“ Dear Prof Rubbia, This is certainly an unusual request. We have a great deal of experience in cryogenic gases and their storage, including gases around the same temperature as Argon. We have not done an argon project but we can see that our experience should transfer over without too much difficulty (I am not sure that anyone will have done anything like this on this scale).

To reply to your specific points, storage tanks, including the associated process issues (which will be significant), safety matters, etc.

yes we can offer expertise in large cryogenic As far as costs are concerned, this is a difficult one to answer right now - to do so, we think a small feasibility type study might be needed. We could do that for you, approximate timescale say 6 weeks , costs IRO UK£ 12,000. We have worked with CERN before, so we are, I think, already "in the database" but I know you need to jump through hoops to get work done. But let me know if this is of interest or, indeed, if there is anything more at this stage we can do for you.

Best regards John Thompson”

André Rubbia - November 2003 54

André Rubbia - November 2003 55

What we get for 100 ktons



Number of targets for nucleon stability:

 6  10 34 nucleons  t

p /Br > 10 34 years



T(yr)

 e @ 90 C.L.



Low energy superbeams or beta-beams:



460

n  CC per 10 21 2.2 GeV protons (real focus) @ L = 130 km 

15000

n e CC per 10 19 18 Ne decays g =75 

Atmospheric:



10000

atm events / year 

≈100

n t 

Solar:



≈324000

CC /year from oscillations solar neutrinos / year @ E e 

Supernova type-II:



≈20000

events @ D=10 kpc > 5 MeV

Of course, MASS is not the whole story!



We want the factor MASS



EFFICIENCY BACKGROUNDS low!!!

high and

André Rubbia - November 2003 56

  

Proton decay searches

The baryon number violation could be mediated through very heavy particles. This would make this process possible, but rare at low energy.

u d u

Super heavy gauge boson

e

u u



  0

u d u

Super heavy SUSY n

s u



Large variety of decay modes accessible



study branching ratios free of systematics

 n

 

Background free searches for even for 10 years running!!!



linear gain in sensitivity with exposure



In case of negative results:

 t

p > O (10

3435

years)

in 10 years of data taking

André Rubbia - November 2003 57

10 35

Proton decay: Sensitivity vs exposure

p  K + n 10 34 p  e +  0 65 cm p  K + n e André Rubbia - November 2003 1 year exposure !

Nuclear effects in signal: fully embedded in FLUKA nuclear model 58

Neutrino physics potentials highlights

    Atmospheric neutrinos  Observation free of experimental biases!

 Detection down to production thresholds  Complete event final state reconstruction  Measurement of all neutrino flavors in all modes (CC & NC)   Excellent resolution on L/E reconstruction  A “MONOLITH” every 3 months Direct t appearance search Supernova neutrinos (see JCAP 09(2003)005)  Detect all neutrino flavors and CC&NC  Study q 13 and mass hierarchy  Study supernova physics Solar neutrinos  Huge statistics, high precision measurements, excellent energy resolution Neutrinos from accelerators (superbeams, b -beams or NF)    Precise measurement of D m 2 23 , q 23 , q 13 Matter effects, sign of D m 2 23 First observation of n e  n t (unitarity of mixing matrix)  CP violation André Rubbia - November 2003 59



Parameters

 Unless otherwise noted we assume in the following: D

2 12  7  10  5

2 D

2 23  q 12 q 13   3

2.5

 10  3

2 32

, q 23  45

André Rubbia - November 2003 60

CP-phase effect at L=130 km

D

N(



=



/2)– N(



=0)

Compares oscillation probabilities as a function of E n predictions of the spectrum in absence of CP violation measured with wrong-sign muon event spectra, to MonteCarlo André Rubbia - November 2003 b

-beam

A cross-check !

conventional 61

The physics program at the Superbeam

    One can study a high intensity conventional superbeams taking advantage of the    (1) excellent energy resolution, (2) particle identification capabilities and (3) excellent imaging in particular for low energy events (particle detectable down to ≈0 momentum) Beam:   n  or n  (sign of beam selectable) Given baseline should be “low” energy (typ. ≈1-4 GeV) Signal:  n  n e or n  n e Backgrounds:   Intrinsic contamination of the beam ( n e / n   0 misidentification typ. 0.5-1% ) André Rubbia - November 2003 62

 

Rejection



based on imaging

Based on full simulation, digitization, noise and automatic reconstruction of events Algorithm: cut for 90% eff. electrons 1. Events with vertex: conversion within 1cm (3 wires) of vertex R 1 ≈19 2. Single/double mip R 2 ≈30 (preliminary)

Single photon rejection

cut

Preliminary 1 π 0 (MC)

Imaging provides ≈2



10 -3 efficiency for single



André Rubbia - November 2003

MeV/cm

 

Rejection



based on imaging

π 0    surviving dE/dx separation cut (total 31 events out of 1000 1GeV π 0 ) 21 events: Compton scattering 5 events: Asymmetric decays (partners have less than 4 MeV) 2 events: positron annihilation immediately  π 0 1 event: positron make immediate Bremsstrahlung taking >90% of energy rejection improves with energy: 5% @ 0.25 GeV, 4% @ 0.5 GeV, 3% @ 1 GeV, 2% @ 2 GeV Compton electron

Full simulation+digitization+noise

 Further rejection by kinematical cuts (depends on actual beam energy profile)  E.g. n n  n π 0 n : precise mass reconstruction André Rubbia - November 2003 

Reduce to negligible level

Definitions for E & L optimization

 In order to estimate sensitivity to CP-violation phase, we define three quantities based on the integrated number of events and D  

N(



=



/2)– N(



=0)

“oscillated” background=

intrinsic

3%

André Rubbia - November 2003 65

Energy integrated rates: conventional beam

 +

focusing

 

focusing

intrinsic

n  André Rubbia - November 2003

“oscillated” intrinsic

Results: conventional beam

Real focusing (see

New J.Phys.4:88,2002

);

All rates normalized to 100 kton

André Rubbia - November 2003

The rules “Merit = pot



E proton ” and “optimal L” hold

2.2 GeV protons 20 GeV protons

André Rubbia - November 2003

L=120 km L=730 km

  

The physics program at the

-beam

    One can study beta-beams taking advantage of the  (1) excellent energy resolution,   (2) particle identification capabilities (3) excellent imaging in particular for low energy events (particle detectable down to ≈0 momentum)  (4) separation pions from muons (Cerenkov light) Beam:   n e or n e (ion selectable) Acceleration ion gives a relatively “low” energy (typ. g ≈100-250) Signal:  n e n  or n e n  Backgrounds:   Beam is pure!

 misidentification (in particular, NC with pion production is dangerous background)  n Since we want the maximum of the oscillation to lie above muon production threshold for appearance, there is a minimum baseline !

 n  1.27

L E

min D

2   

min  1.27



2  110

MeV L

min   110

MeV

1.27

2  136

km for

2  2  10 3

2 André Rubbia - November 2003 69

  

Beta beam: charged pion background rejection



Signal:

n 

Background: µ Use combination of charge imaging (∫(dE/dx)dx= T

kin

) & Cerenkov light readout (

)

  n



Reduce to negligible level

W/o Cerenkov: optimize neutrino energy to suppress pion production at the cost of oscillated event rate (proportional to g ) André Rubbia - November 2003 70

Beta beam: charged pion background rejection

    Momentum cut Range  Many pions interact Particle stops Cerenkov based rejection:  Kinetic energy is measured from deposited charge  Velocity is measured from Cerenkov photon counting  The two can be combined to discriminate pions from muons André Rubbia - November 2003 71



Definitions for E & L optimization

In order to estimate sensitivity to CP-violation phase, we define three quantities based on the integrated number of events and D  

N(



=



/2)– N(



=0)

“oscillated” Background=

pions from NC

1%

André Rubbia - November 2003 72

Energy integrated rates:

-beam

André Rubbia - November 2003 W/o Cerenkov With Cerenkov 73

Baseline&energy optimization:

-beam

Ion decays needed to achieve 3

of

D  André Rubbia - November 2003 W/o syst. With 1% syst. 74



Sensitivity to CP-violation: example

Ne

=75 L=130 km 10 years @ 2x10

ions/yr 1% systematic

2 12  7  10  5

2 D

2 23 q 12   2.5

 10  3

, q 23  45

Complete coverage of CP space!

André Rubbia - November 2003 75

   

Conclusion

The liquid Argon TPC technology has recently regained a strong interest in the community , after the  Successful assembly and operation of the ICARUS T600 that demonstrated that the LAr TPC Technology is mature  The realization of the enormous physics potential granularity imaging and extremely high resolution offered by high The physics potentials of a 100 kton LAr detector competes favorably with that of a megaton water Cerenkov detector  Neutrino physics (e.g. CP) & ultimate no-background proton decay The design of a single-tanker 100 kton liquid Argon detector will be pursued, taking advantages of possible advances in the LAr TPC technology  Bi-phase operation with charge amplification for long drift distances  Imaging+Scintillation+Cerenkov performance readout for improved physics  Giant “boiling” cryostat (LNG technology)  Giant LNG tankers known to exist on surface  Underground LNG tankers??? Do not know if they exist  First cost estimate should be known (Technodyne, Q1 2004) Including the digging of the cavern, it might well be that the 100 kton liquid Argon detector would be more cost advantageous than the 1MT H 2 O André Rubbia - November 2003 76

Soyons optimistes…

 If you like it, we might have found a name for it: André Rubbia - November 2003 77