Andr

1
Large liquid Argon detectors
Giant

• André Rubbia, ETH Zürich
• (ICARUS Collaboration)
• Paris meeting, November 2003
• Simulations performed by Paola Sala (ETHZINFN)

2
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 RD
• It has recently regained a strong interest in the
  community, after the
• The successful assembly and operation of the
  ICARUS T600 that demonstrated that the technology
  is mature
• The realization of the enormous physics potential
  offered by high granularity imaging and extremely
  high resolution, in the context of
• Underground physics (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, LOIs,
  etc have recently appeared concerning liquid
  argon detectors, from the smallest (10-100 tons)
  to the biggest (gt100 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 (100kton) must be investigated. This is
  the subject of this talk.

3
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)
4
ICARUS T3000 A Second-Generation Proton Decay
Experiment and Neutrino Observatory at the Gran
Sasso Laboratory
100 m
nK
5
ICARUS RD - 50 liter prototype in CERN West
Area neutrino beam
6
ICARUS T600 cosmic rays on surface
Shower
25 cm
85 cm
265 cm
142 cm
Muon decay
Hadronic interaction
Run 960, Event 4 Collection Left
Run 308, Event 160 Collection Left
7
ICARUS T300 cryostat (1 out of 2)
300000 kg LAr T300
8
ICARUS T300 prototype
Cryostat (half-module)
View of the inner detector
4 m
20 m
4 m
Readout electronics
9
Liquefied rare gases TPC basic ideas

• Ideal materials for detection of ionizing tracks
• Dense (g/cm3 103 x rgas), 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 Density (r/cm3) Energy loss dE/dx (MeV/cm) Radiation length X0 (cm) Collision length l (cm) Boiling point _at_ 1 bar (K) Electron mobility (cm2/Vs)
Neon 1.2 1.4 24 80 27.1 highlow
Argon 1.4 2.1 14 80 87.3 500
Krypton 2.4 3.0 4.9 29 120 1200
Xenon 3.0 3.8 2.8 34 165 2200



10
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 bgt1/n)
M. Suzuki et al., NIM 192 (1982) 565
11
Comparison rare gases
LAr LKr LXe
Density g/cm3 1.39 2.45 3.06
dE/dx MeV/cm 2.11 3.45 3.89
I eV 15.76 14.00 12.13
We-ion eV 23.60.3 20.51.5 16.41.4
Wg eV 19.5 52 38
Scintillation photons/MeV photons 50000 19000 26000
Decay const ns 6(23), 1600(77) 2(1),85(99) 2(77),30(33)
Scintillation peak nm 128 147 174
Rayleigh scattering length for scintillation cm 90 60 30
12
Comparison water - liquid Argon
Water Liquid Argon
Density (g/cm3) 1 1.4
Radiation length (cm) 36.1 14.0
Interaction length (cm) 83.6 83.6
dE/dx (MeV/cm) 1.9 2.1
Refractive index (visible) 1.33 1.24
Cerenkov angle 42 36
Cerenkov d2N/dEdx (b1) 160 eV-1 cm-1 130 eV-1 cm-1
Muon Cerenkov threshold (p in MeV/c) 120 140
Scintillation No Yes (50000 g/MeV _at_ l128nm)
Cost 1 CHF/liter (Evian) 1 CHF/liter
13
Comparison Water - liquid Argon
A new way to look at rare events
14
Electron drift properties in liquid Argon
3 m
15
The Liquid Argon TPC (I)
UV Scintillation Light L
Readout planes Q
Time
Edrift
Drift direction

• High density
• Non-destructive readout
• Continuously sensitive
• Self-triggering
• Huge scintillation T0

Low noise Q-amplifier
Continuous waveform recording
16
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 lt 0.1 ppb O2 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

17
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 B0.5-1T
• 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 B1 T
• Underground physics (proton decay, supernova,
  atm, solar, )
• 100 kton non magnetized

Different optimizations for different kinds of
physics (Mini, medium, large, XL)
18
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 and would cost 200 M
  (conservative)
• This would be ok for superbeams (e.g. offaxis)
• 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

19
The ICARUS T1200 Unit

• 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

Detailed engineering project was produced by Air
Liquide (June 2003) T1200 cryostat ready for
tendering
20
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 RD 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 RD efforts

21
100 kton liquid Argon TPC
Basic features

1. Charge imaging scintillation Cerenkov light
   readout for complete event information
2. Charge amplification to allow for extremely long
   drifts
3. Single 100 kton boiling cryogenic tanker with
   Argon refrigeration

22
100 kton liquid Argon detector
Electronic crates
f70 m
h 20 m
Perlite insulation
23
Front view
h 20 m
f70 m
24
Access and highway tunnel
highway
Access
25
Access tunnel and highway tunnel
Access
Highway tunnel
26
Detector and highway tunnel
Highway tunnel
Detector
27
Open detector
Gas Argon
Liquid Argon
Drift
28
Summary parameters
Dewar 70 m, height 20 m, passive perlite insulated, heat input 5W/m2
Argon storage Boiling argon, low pressure (lt100 mbar overpressure)
Argon total volume 73118 m3 (height 19 m), ratio area/volume15
Argon total mass 102365 tons
Hydrostatic pressure at bottom 3 atm
Inner detector dimensions Disc f 70 m located in gas phase above liquid phase
Electron drift in liquid 20 m maximum drift, HV2 MV for E1KV/cm, vd2 mm/µs, max drift time 10 ms
Charge readout view 2 independent perpendicular views, 3mm pitch, in gas phase (electron extraction) with charge amplification (typ. x100)
Charge readout channels 100000
Readout electronics 100 ICARUS-like racks on top of dewar (1000 channels per crate)
Scintillation light readout Yes (also for triggering), 1000 immersed 8 PMT with WLS (TPB)
Visible light readout Yes (Cerenkov light), 27000 immersed 8 PMTs or 20 coverage, single photon counting capability
29
Charge readout
30
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 _at_ 1 KV/cm, diffusion
  readout pitch 3 mm

Electron drift in liquid 20 m maximum drift, HV2 MV for E1KV/cm, vd2 mm/µs, max drift time 10 ms
Charge readout view 2 independent perpendicular views, 3mm pitch
Maximum charge diffusion s2.8 mm (v2Dtmax for D4 cm2/s)
Maximum charge attenuation e-(t/ tmax) 1/150 for t2 ms electron lifetime
Needed charge amplification 102 to 103
Methods for amplification Extraction to and amplification in gas phase
Possible solutions Thin wires (f30mm)pad readout, GEM, LEM,
31
Electron extraction in Ar-biphase (ICARUS RD)
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
32
Amplification near wires à la MWPC

• Amplification in Ar 100 gas up to factor G100
  is possible
• GARFIELD calculations in pure Ar 100, T87 K,
  p1 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 _at_ 3.5kV
e-
Wire f30mm
102
PCB with strips
33
Gas Electron Multiplier GEM (F. Sauli et al.)
100x100 mm2
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. 
34
GEM in dense rare gases (Buzulutskov et al.)
Buzulutskov et al, IEEE transaction on NS,
e-print physics/0308010 Buzulutskov et al,
NIMA513256-259 (2003)
GEM
Gas phase
GEM
GEM
Liquid phase
35
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. Collar J.
Miyamoto I.P.J. Shipsey
LEM bottom (anode) signal
LEM top (cathode) signal
36
LEM with Argon (ICARUS RD)
PRELIMINARY
Detection of charge signal and scintillation
light produced during amplification
400x400 mm2
Holes f 1 mm
37
Light readout
38
UV light readout (ICARUS RD)

• 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 107 _at_ 1400 V peak Q.E. (400-420
nm) 18 (10 cold) Trise 5 ns, FWHM 8 ns
Lally et al., NIMB 117 (1996) 421
39
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)

Refractive index
Rayleigh scattering
Data consistent with Cerenkov emission
dN/dx(160-600nm) 700 g/cm (b1)
40
Boiling cryogenic tanker
We consider Phase 1 tanker filling Phase 2
running (refrigeration)
41
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 and 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,
• The Liquid Argon is used to fill the experiment.
  Liquid Oxygen and Liquid Nitrogen can be sold

42
Cryogenic parameters initial filling phase
Liquid Argon 1st filling time 2 years (assumed)
Liquid Argon 1st filling rate 1,2 liters/second or 150 tons/day
Argon gas equivalent 85000 m3/day
Air volume equivalent (Ar 1) 8500000 m3/day (205 m)3 /day
Ideal power of separation of Argon mixture 600kW (assuming for Argon 354 kJ/kg)
Assumed efficiency 5
Estimated power for Argon separation 12 MW
Ideal Argon liquefaction power 817kW (assuming for Argon 478 kJ/kg)
Assumed efficiency 5
Estimated Argon Liquefaction power 16 MW
Estimated total plant power 30 MW
Note initial cooling of tanker not included
43
Ideal works for liquefaction and separation
Basic thermodynamics
R.F. Barron, Cryogenic Systems, 2nd edition 1985
(Oxford)
44
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 LN2 since it is a
  priori cheaper than LAr
• However, taking advantage of the requirement of a
  local liquid argon factory, we think that it
  would be much more advantageous to use Argon
  itself to refrigerate the detector (aka keep
  filling liquid Argon to replace what
  evaporates)
• 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 (LN2,
  )

45
The dedicated cryogenic complex
Electricity
Air
Hot GAr
W
Underground complex
GAr
LAr
Q
External complex
Joule-Thompson expansion valve
Heat exchanger
Argon purification
LN2,
46
Cryogenic parameters boiling
Dewar f 70 m, height 20 m, passive 3 m thick perlite insulated, assumed equivalent heat input 5 W/m2
Total area 12100 m2
Total heat input 60500 W
Liquid Argon evaporation rate 0.27 liters/second or 23000 liters/day
Fraction of total evaporation rate 0.03 of total argon volume per day
Time to totally empty tanker by evaporation 9 years (!)

• Notes
• Heat loss should be conservative for 3 meter
  thick perlite and includes heat input from
  supports, instrumentation (cables), etc.)

47
Thermal conductivities gas-filled insulations
R.F. Barron, Cryogenic Systems, 2nd edition 1985
(Oxford)
Perlite 8.8 W/m for T80K
48
Cryogenic parameters refilling (refrigeration)

• The dedicated cryogenic plant must hence produce
  liquid argon to refill what has evaporated

Liquid Argon refilling rate 0.3 liters/second or 23000 liters/day
Argon gas equivalent 0.2 m3/s or 200 l/s
Ideal Argon liquefaction power 180kW (assuming for Argon 478 kJ/kg)
Assumed efficiency 5
Estimated Argon Liquefaction power 3.6 MW
Air volume equivalent (Ar 1) 20 m3/s or 20000 l/s
Ideal power of separation of Argon mixture 130kW (assuming for Argon 354 kJ/kg)
Assumed efficiency 5
Estimated power for Argon separation 2.6 MW
Estimated total power 6.2 MW
49
LNG facts

• WHAT IS IT? When natural gas is cooled to a
  temperature of approximately -160C 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? 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 low, less than 5 psig.
• HOW IS IT KEPT COLD? 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 "autorefrigeration". 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 (-423F)
  and liquid oxygen (-296F). LNG technology grew
  from NASA's advancement.

50
Cryogenic storage tanks for LNG
51
Liquefaction of LNG and transport via ships
Liquefaction plant in Oman
e.g. Nigeria LNG (1010 m3/year)
Filled with LCH4
Up to 145,000m3
52
(No Transcript)
53
Technodyne International Limited Unit 16
Shakespeare Business Center Hathaway Close, 
Eastleigh, Hampshire, SO50 4SR
54
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, yes we
  can offer expertise in large cryogenic storage
  tanks, including the associated process issues
  (which will be significant), safety matters, etc.
  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

55
Physics Overview
56
What we get for 100 ktons

• Number of targets for nucleon stability
• 6 ? 1034 nucleons ? tp /Br gt 1034 years ?
  T(yr) ? e _at_ 90 C.L.
• Low energy superbeams or beta-beams
• 460 nm CC per 1021 2.2 GeV protons (real focus)
  _at_ L 130 km
• 15000 ne CC per 1019 18Ne decays g75
• Atmospheric
• 10000 atm events / year
• 100 nt CC /year from oscillations
• Solar
• 324000 solar neutrinos / year _at_ Ee gt 5 MeV
• Supernova type-II
• 20000 events _at_ D10 kpc

Of course, MASS is not the whole story! ? We want
the factor MASS ? EFFICIENCY high and BACKGROUNDS
low!!!
57
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.

• Large variety of decay modes accessible
• ? study branching ratios free of systematics
• Background free searches for even for 10 years
  running!!!
• ? linear gain in sensitivity with exposure
• In case of negative results
• ? tp gt O (10 34-35 years) in 10 years of data
  taking

58
Proton decay Sensitivity vs exposure
p?Kn
1035
p?ep0
65 cm
1034
p ? K ?e
p425 MeV
1 year exposure !
Nuclear effects in signal fully embedded in
FLUKA nuclear model
59
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 CCNC
• Study q13 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 Dm223, q23, q13
• Matter effects, sign of Dm223
• First observation of ne ? nt (unitarity of
  mixing matrix)
• CP violation

60
Parameters

• Unless otherwise noted we assume in the following

61
CP-phase effect at L130 km
??? N(??/2) N(?0)
Compares oscillation probabilities as a function
of E? measured with wrong-sign muon event
spectra, to MonteCarlo predictions of the
spectrum in absence of CP violation
b-beam
conventional
A cross-check !
62
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
• nm or nm (sign of beam selectable)
• Given baseline should be low energy (typ. 1-4
  GeV)
• Signal
• nm?ne or nm?ne
• Backgrounds
• Intrinsic contamination of the beam (ne/ nm typ.
  0.5-1 )
• p0 misidentification

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Rejection p0 based on imaging

• Based on full simulation, digitization, noise and
  automatic reconstruction of events
• Algorithm cut for 90 eff. electrons
• Events with vertex conversion within 1cm (3
  wires) of vertex R119
• Single/double mip R230 (preliminary)

Single photon rejection
Preliminary
cut
1 p0 (MC)
ltdE/dxgt MeV/cm
Imaging provides 2?10-3 efficiency for single p0
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Rejection p0 based on imaging

• p0 surviving dE/dx separation cut (total 31
  events out of 1000 1GeV p0)
• 21 events Compton scattering
• 5 events Asymmetric decays (partners have less
  than 4 MeV)
• 2 events positron annihilation immediately
• 1 event positron make immediate Bremsstrahlung
  taking gt90 of energy
• p0 rejection improves with energy 5 _at_ 0.25 GeV,
  4 _at_ 0.5 GeV, 3 _at_ 1 GeV, 2 _at_ 2 GeV

Compton electron
Full simulationdigitizationnoise

• Further rejection by kinematical cuts (depends on
  actual beam energy profile)
• E.g. nn ? np0n precise mass reconstruction

? Reduce to negligible level
65
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

??? N(??/2) N(?0)
backgroundintrinsic ne
oscillated
3
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Energy integrated rates conventional beam
p focusing
p- focusing
L730 km
L130 km
intrinsic ne
intrinsic nm
oscillated
67
Results conventional beam
Real focusing (see New J.Phys.488,2002) All
rates normalized to 100 kton
L730 km
L130 km
The rules Merit pot ? Eproton and optimal L
hold
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2.2 GeV protons
20 GeV protons
L120 km
L730 km
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The physics program at the b-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
• ne or ne (ion selectable)
• Acceleration ion gives a relatively low energy
  (typ. g100-250)
• Signal
• ne ?nm or ne ?nm
• Backgrounds
• Beam is pure!
• m misidentification (in particular, NC with pion
  production is dangerous background)
• Since we want the maximum of the oscillation to
  lie above muon production threshold for
  appearance, there is a minimum baseline !

70
Beta beam charged pion background rejection
Signal
µ
Use combination of charge imaging (?(dE/dx)dx
Tkin) Cerenkov light readout (b)
Background
p
? Reduce to negligible level
W/o Cerenkov optimize neutrino energy to
suppress pion production at the cost of
oscillated event rate (proportional to g)
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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

72
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

??? N(??/2) N(?0)
oscillated
Backgroundpions from NC
1
73
Energy integrated rates b-beam
L130 km
L400 km
W/o Cerenkov
With Cerenkov
74
Baselineenergy optimization b-beam
Ion decays needed to achieve 3s of Dd
L130 km
L400 km
L130 km
W/o syst.
With 1 syst.
75
Sensitivity to CP-violation example
18Ne g75 L130 km 10 years _at_ 2x1018 ions/yr
1 systematic
Complete coverage of CP space!
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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
  offered by high granularity imaging and extremely
  high resolution
• 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
• ImagingScintillationCerenkov readout for
  improved physics performance
• 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 H2O

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Soyons optimistes

• If you like it, we might have found a name for it

GLACIER Giant Liquid Argon Cerenkov charge
Imaging ExpeRiment