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In fact, in K2K the original near Sci-fi has been replaced by the improved SCI-bar detector.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