T2K-LAr A liquid Argon TPC for the T2K
neutrino experiment
D.Autiero (IPNL) GDR neutrino, Marseille
14/3/05
e QE
• low E (<1 GeV) Super-Beam: 1021 pot/year
(3.3x1014 50 GeV pot/s x 130 days x 5 years)
• SK detector: 22.5 kton x year
• @ 2° 3000 CC/year (x10 w.r.t. K2K)
• 0.2% e contamination and ° BG
e contamination
Tunable off-axis beam
K decay
decay
T2K disappearance
Assume 23 = /4
• measure m223 with 10-4 eV2 error
• know if sin2223 = 1 (0.01 uncertainty)
5 years running
Assumed systematic errors (to be reduced by using near detectors!)
Far-near ratio: 10%
Non QE/ QE ratio: 20%
Energy scale: 4%
P( x) ~ cos413 sin2223 sin2 (m223 L/ 4E)
The experience of K2K has shown that a fine grained detector in front of the WC near detector is necessary for oscillation analysis since:
the energy spectrum measured by the WC (Evis = E) cannot be used to predict the oscillated spectra at SK due to the lack of knowledge of all the details of the neutrino interactions (E = E + Ehad)
In fact, in K2K the original near Sci-fi has been replaced by the improved SCI-bar detector.
The fine grained detector mass of K2K must be accordingly scaled up in the T2K 2 km site (~ 100 ton). This is not a practical solution for a volume-instrumented detector.
QE
inelastic
E~60MeV<10% measurement
E(reconstructed) – E(true)
1-sin22
non-QEresolution
m2
When adding protons and detector mass isn’t enough…When adding protons and detector mass isn’t enough…
For any of these experiments, detectors see different mixes of events between near and far. Cross section uncertainties don’t all cancel!
Looking for differences between and anti- probabilities of at most 15-20%…need to measure probabilities to 5% or better for a 3 determination!
Problem: no cross sections at these energies are known any better than about 20%...
Minera will provide precise measurements, but we still need anti- cross sections…NOvA pre-PD rates
D. Harris, proton driver review
T2K eappearance: measurement of 13
Sensitivity: 5 years, OA2°
Expected events in 5 years for :
Beyond 5 years
Total Bck uncertainty should be less than 10 %
For the appearance search the two main BGs (prompt e and 0) have very different systematics: measure them separately ??
Ideal: fine grained detector with good e/ 0 separation capabilities
Japanese program phase 2: short L, low E
• intensity up to 4 MW
• detector mass up to 1 Mton
• no matter effects: assume mass hierarchy determined elsewhere
Major T2K beam upgrade, new Hyper-K detector1) low energy: low ° BG 2) gigantic water Cerenkov: good e ID
demanding requirements: 2% syst. from BG subtraction and 2% from data selection
low E low x-section
The 1 kton WC detector at the 2km location would profit if operated in conjunction with a muon ranger and a 100 ton fine grained detector, able to reconstruct recoiling protons, low momentum hadrons, asymmetric decays of 0, etc., in an unbiased way.
A liquid Argon (LAr) Time Projection Chamber (TPC) allows to reach the required mass while maintaining the high granularity. The T2K experiment will profit of its distinctive features of a fully active, homogeneous, high-resolution device.
A LAr TPC will provide means to perform: an independent measurement of CC events; a measurement of NC events with clean π0 identification for an independent
determination of systematic errors on the NC/CC ratio; the measurement of the intrinsic eCC background; last but not least, the collection of a large statistical sample of neutrino interactions in the
GeV region for the study of the quasi-elastic, deep-inelastic and resonance modelling and of nuclear effects.
Measurement of antineutrino QE CC events via topological id ?
coherent
e QE
Real neutrino in ICARUSReal neutrino in ICARUS
Liquid Argon TPCLiquid Argon TPC at 2 Km at 2 Km
High granularity : 0.02 X0 sampling
Tracking + Calorimetry100 Ton mass easely feasible
MMilestonesilestones
August 2004: T2K general meeting
Sept 2004-now: Discussion at the level of the 2km working group Design of the T2K LAr detector Optimization of geometry and definition of the T2K-LAr detector layout in
underground hall Definition of dedicated infrastructure for LAr
Since Nov 2004, a working group is active at writing a “comprehensive” and “scientific” document. Deadline ≈ May 2005. The baseline detector parameters are frozen and initial performance studies
have been accomplished. Innovative features and recent technological advances are well included in
the detector implementation. We have extracted the relevant information for the 2km Appendix.
T2K-LAr working group (17 institutes, 41 members)T2K-LAr working group (17 institutes, 41 members)
Columbia University: E. Aprile, K. Giboni, M. Yamashita
IPN-Lyon : D. Autiero, Y. Déclais, J. Marteau
ETHZ: W. Bachmann, A. Badertscher, M. Baer, Y. Ge, M. Laffranchi,
A. Meregaglia, M. Messina, G. Natterer, A. Rubbia
Granada University: A. Bueno, S. Navas-Concha
L’Aquila University: F. Cavanna, G. Piano-Mortari
UCLA: D. Cline, B. Lisowski, C. Matthey, S. Otwinowski
Yale University: A. Curioni, B. Flemming
INFN Naples: A. Ereditato, G. Passeggio, V. Vanzanella
CIEMAT: I. Gil-Botella, P. Ladron de Guevara, L. Romero
Silesia University (Katowice): J. Holeczek, J. Kisiel
Warsaw University: D. Kielczewska
INFN Frascati: G. Mannocchi
LNGS: O. Palamara
Torino University: P. Picchi
Soltan Institute (Warszawa): P. Przewlocki, E. Rondio
Wroclaw University: J. Sobczyk
Niewodniczanski Institute (Krakow): A. Szelc, A. Zalewska
UK has expressed interest but is presently committed to 280 m
UK has expressed interest but is presently committed to 280 m
LAr detector performance studiesLAr detector performance studies Dedicated simulation tools for T2K-LAr geometry have been developed to
assess detector performance
Results are available on e/0 separation Hadron identification Event reconstruction, selection and classification Stand-alone muon momentum resolution Neutrino and hadronic system energy resolution Event kinematics reconstruction Events in inner target Nus/antinus statistical separation (work in progress)
Write-up available for 2km Appendix
Further integration of the liquid Argon software into official 2km SW on-going
Physics items to be studied next: Prediction of events at SK Prediction of e events and 0 background at SK
When vertex known, combine with prob to convert within 1 cm: 5.4%
e/pi0 separation e/pi0 separation
dE/dx cut efficiency:
Combined, aim at: 0.2% π0 efficiency by imaging for 90% electron efficiency
pair 18cm
Sampling : 0.02 X0
T2K disappearance P( x) ~ cos413 sin2223 sin2 (m223 L/ 4E)
e.g. : nQE/QE measurement in LAr:
(work in progress)
nQE
QE
Neutrino energy reconstructionNeutrino energy reconstruction
nQE
EMC Evis
EMC
(%)
Design features of T2K-LArDesign features of T2K-LAr
The proposed design takes advantage from the experience of ICARUS. However, innovative features and technological advances are included in the detector design. In particular:
Cryostat has a design that follows the codes of conventional cryogenic-fluid pressure storage-vessels (ASME Boiler & Pressure Vessel Code, Sect. VIII (www.asme.org)). Design and construction according to these standards will ensure a reliable and safe cryogenic operation
Cooling is based on heat engine with Ar as medium (avoid LN2)
Inner detector has an innovative and simple design (to limit complexity & cost)
Immersed Cockroft-Walton to generate uniform drift of 1 kV/cm over 2 m (to exploit very high electric rigidity of LAr)
Inner target allows to measure events on Water / CO2
New LAr purity monitoring systems
Scintillation light readout based on DUV sensitive PMT
Electronics based on commercial preamps and newly designed digital part (since triggered by beam timing).
≈28 m
≈15m
Artistic view of LAr integration in 2km underground site Artistic view of LAr integration in 2km underground site
Incoming neutrino beam
Total LAr mass ≈ 315 tons, 100 tons fid., total cryostat weight ≈ 100 tons
5 m
Liquid ArgonActive volume
4.5m
4.5m
Racks
Supporting structure
7,2 m
8,5 m
Close viewClose view(open endcap)(open endcap)
HV
Charge readoutelectronics
Scintillation light readout
≈7,2 m
Front viewFront view
Wire chambers
Cathode and H2O/CO2 inner target5 tons
Liquid Argonimaging volume
Liquid Argon processLiquid Argon process
Buffer
Dewar
Liquid Purification
Heat exchanger and expansion valve
LAr
Vent + compressor
High pGAr
Burst-disk
Pressure-relief valve
Ven
t valve
Vacuum insulation+ Double liquid Argon containment
Qin ≈ 500WBoiloff ≈200 lt/day10–3 / day
3500 lt/hrQpurif ≈ 1kW
Electrical power (5% eff):W/o recirculation ≈ 10kWW recirculation ≈ 30 kW
Linde-Hampson refrigeration
Installation procedureInstallation procedure Adopted strategy:
Assemble detector at surface (e.g. assembly hall with crane at KEK or JAERI) Transport and lower detector into underground hall as a single item (≈ 100 tons),
however this requires the full shaft diameter (≈8.5 m) Minimize underground activities
Main phases:Year 1 Year 2 Year 3
Proposal to lower detector as single item
Shock absorber
Proposal to lower detector as single item
Shock absorber
OutlookOutlook
Comprehensive LAr TPC document progressing well. Expect to complete it by May 2005, to include all latest achievements and integration, to be used as a reference for scientific case and financial requests.
The T2K-LAr baseline detector parameters are frozen. Innovative features and recent technological advances are well included in the detector implementation. No major R&D required. However, detailed technical work is in progress in all sub-items.
Initial physics performance studies have been accomplished Extracted enough information and included it into the 2km Appendix.
Next steps:1. Final assessment of the physics added-value of LAr detector in T2K2. More detailed studies on installation & integration issues3. Detailed costing, spending and construction profiles as soon as principle
approval of the 2km physics programme. Ideally within Fall 2005.
Chris Walter2km review, last week
Chris Walter2km review, last week
Engineering design of cryostatEngineering design of cryostatTotal LAr mass ≈ 315 tons, total weight ≈ 100 tons, two independent stainless steel vessels, multilayer super-insulation in vacuum.
Likely to be constructed and assembled in Japan to avoid costly transportation.
3D engineering:
Finite element analysis:
Thermal analysis:
Inner target: two geometrical optionsInner target: two geometrical options
Geometry to be defined following laboratory results and MC simulations
mass 2.69 ton 5.37 ton 10.74 ton
width 12.5 cm 25 cm 50 cm
QE protons 50% 30% 19%
QE full rec. 36% 22% 14%
QE per 1021pot 1178 1440 1832
nonQE protons 32% 22% 16%
nonQE + 94% 85% 71%
nonQE 0 95% 85% 76%
nonQE full rec. 27% 17% 9%
nonQE per 1021pot 500 630 670
Reconstruction of MC events in inner target
Recoil protonp=660 MeV
QE event
Inner detector structureInner detector structure
4.5 m x 4.5 m x 5 m stainless-steel supporting structure for wire planes, PMTs, auxiliary systems, cathode, inner target. Two independent readout chambers (LR)
Conceptual design, stress calculation.
Engineering design in progress.
Wire frame
Field shaping electrodes
Cathode + inner target
Supporting beams
Main parameters of the TPCMain parameters of the TPC
Details of wire planesDetails of wire planesBaseline option: two perpendicular planes per chamber; simple wire sustaining design with wire pre-tensioning anchored by slipknots and pins onto wire frame. Optional third vertical plane under study.
Light readout systemLight readout system Needed for T0 definition and possibly independent trigger Two possible options
(A) 8” PMT with WLS coating (B) 2” PMTs with MgF2 window glass for DUV sensitivity Immersed in LAr
Number of PMTs : 60150 HV distribution designed (minimize #feed-through, power dissipation, …)
High voltage systemHigh voltage system Cathode @ 200 kV + field shaping electrodes designed Uniform drift field ≈ 1 kV/cm Immersed Cockroft-Walton HV generator (no HV feed-throughs) Mechanical tolerance studied Field mill for field measurement
Readout electronicsReadout electronics Commercially available front-end analog board (CAEN, 32 channels) Custom-made digital boards to interface to PCs ≈10’000 channels in total
LAr purity monitors and slow controlLAr purity monitors and slow control Improved designs of previously custom-built devices. Study of UV laser calibration
A: Detector dewarB: LAr PurificationC: BufferD: Heat exchanger and expansion valveE: Argon pipesF: Shock absorbersG: Dedicated shaft (ventilation+piping)
B
C
D
A
E
Underground cryogenic infrastructure
F
G
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