Novel LAr TPC developments for neutrino and astrophysics

1. Novel LAr TPC developments for neutrino and astrophysics A. Badertscher, L. Kaufmann, L. Knecht, M. Laffranchi, A. Marchionni, G. Natterer, P. Otiougova, F. Resnati, A. Rubbia, T. Viant ETH Zurich CHIPP Workshop on Detector R&D, June 2008 • A precision detector for • proton decay searches • neutrino oscillation measurements • dark matter searches • GLACIER: a concept for a scalable LAr detector up to ~ 100 kton • necessary R&D steps • LAr LEM-TPC: a novel scalable detector for cryogenic operation • 0.1 x 0.1 m2 test setup • low-noise preamplifiers and DAQ developments • ArDM: a ton-scale LAr detector with a 1 x 1 m2LEM readout • status of the inner detector • cryogenics and first cool down • first tests of the Light readout • Conclusions

2. LAr TPC as neutrino detector • A LAr TPC is the best detector for oscillation searches • measurements of θ13 and mass hierarchy, search for CP violation • provides high efficiency for e charged current interactions • adequate rejection against  NC and CC backgrounds • e/0 separation • fine longitudinal segmentation (few % X0) • fine transverse segmentation, finer than the typical spatial separation of the 2 ’s from 0 decay • e/,h separation • embedded in a magnetic field provides the possibility to measure both wrong sign muons and wrong sign electrons samples in a neutrino factory beam F. Arneodo et al., “Performance of a liquid argon time projection chamber exposed to the WANF neutrino beam”, Phys. Rev. D 74 (2006) 112001 Data collected in 1997 Search for QE events 86 “golden events with an identified proton of kinetic energy larger than 40 MeV and one muon matching NOMAD reconstruction

3. LAr MC: p → K+ ν LAr MC: p → e+π0 LAr TPC as proton decay detector K.L. Giboni “A two kiloton liquid Argon detector for solar neutrinos and proton decay”, NIM 225 (1984) 579 ICARUS Coll. “ICARUS II. A second generation proton decay experiment and neutrino observatory at the Gran Sasso Laboratory”, Sept. 1993 10x efficiency than WC only way to reach 1035 years • A. Bueno, M. Campanelli, A. Ferrari, A. Rubbia “Nucleon decay studies in a large liquid Argon detector”, AIP Conf. proc. 533 (2000) 12 • A. Bueno et al. “Nucleon decay searches with large liquid Argon TPC detectors at shallow depths: atmospheric neutrinos and cosmogenic background”, JHEP04 (2007) 041

4. Giant Liquid Argon Charge Imaging ExpeRiment possibly up to 100 kton Electronic crates A. Rubbia hep-ph/0402110 Venice, Nov 2003 ≈70 m Drift length h =20 m max Passive perlite insulation Single module cryo-tank based on industrial LNG technology GLACIER A scalable detector with a non-evacuable dewar and ionization charge detection with amplification

5. GLACIER concepts for a scalable design • LAr storage based on LNG tank technology • Certified LNG tank with standard aspect ratio • Smaller than largest existing tanks for methane, but underground • Vertical electron drift for full active volume • A new method of readout (Double-phase with LEM) • to allow for very long drift paths and cheaper electronics • to allow for low detection threshold (≈50 keV) • to avoid use of readout wires • A path towards pixelized readout for 3D images. • Cockroft-Walton (Greinacher) Voltage Multiplier to extend drift distance • High drift field of 1 kV/cm by increasing number of stages, w/o VHV feed-through • Very long drift path • Minimize channels by increasing active volume with longer drift path • Light readout on surface of tank • Possibly immersed superconducting solenoid for B-field Scalable detector • LAGUNA: Large Apparatus for Grand Unification and Neutrino Astrophysics FP7 design study to address: • the excavation and preparation of the underground space • the design and construction of the tank • instrumentation • safety aspects including three detector technologies (Water, Scint, LAr) in various possible European sites

6. Steps towards GLACIER ArDM ton-scale LEM readout on 1x1 m2 scaleUHV, cryogenic system at ton scale, cryogenic pump for recirculation, PMT operation in cold, light reflector and collection, very high-voltage systems, feed-throughs, industrial readout electronics, safety (in Collab. with CERN) Small prototypes ➠ ton-scale detectors ➠ 1 kton ➠ ? B-field test direct proof of long drift path up to 5 m ➠ ➠ ➠ ArgonTube: long drift, ton-scale LEM test we are here proof of principle double-phase LAr LEM-TPC on 0.1x0.1 m2 scale 1 kton Test beam 1 to 10 ton-scale Application of LAr LEM TPC to neutrino physics: particle identification (200-1000 MeV electrons), optimization of readout and electronics, possibility of neutrino beam exposure full engineering demonstrator for larger detectors, acting as near detector for neutrino fluxes and cross-sections measurements, … ➠ ➠ 10m 12m

7. LAr LEM-TPC 10 cm drift Maximum sensitive volume 10 x 10 x 30 cm3 Anode 1.5 kV/cm 28 kV/cm LEM 2 1.2 kV/cm 28 kV/cm LEM 1 1.0 kV/cm LAr level 3 kV/cm Grids

8. P. Otiougova, PhD Diss. ETHZ 17704, April 2008 Proof of concept: LEM tests in pure Ar gas MPGDs generally function in gas mixtures: not compatible with double phase operation in LAr Pure Ar Photon feedback Ions induced signal 10 s/div @ 300 K, 1 bar Emult≈ 12 ÷ 13 kV/cm Ar/CO2 90/10 Ions induced signal Electrons induced signal 2 s/div Ar/CO2 90/10 Faster signal achieved by drifting electrons to an anode and so enhancing the electron component signal 200 ns/div

9. Double stage LEM with Anode readout Signal collection plane Bottom LEM 10 x 10 cm2 16 strips 6 mm wide Anode Top LEM • Produced by standard Printed Circuit Board methods • Double-sided copper-clad (18 μm layer) FR4 plates • Precision holes by drilling • Gold deposition on Cu (<~ 1 μm layer) to avoid oxidization • Single LEM Thickness: 1.55 mm • Amplification hole diameter = 500 µm • Distance between centers of neighboring holes = 800 µm 10 x 10 cm2 16 strips 6 mm wide

10. Technical developments 1 HV feedthrough Miniaturized kapton cables LEMO 30 kV connector HV connections to LEM planes (~8 kV) Voltage divider for field shapers HV connections to cathode and grids (up to ~30 kV) All materials must be compatible with UHV and cryogenic application

11. Technical developments 2 kapton flex-prints 32 channels/cable to ZIF connectors To preamplifiers vacuum tight, epoxy-sealed feedthrough Capacitor-based Levelmeters ZIF connectors scalable LEM design

12. Measured values 4 different shaping constants Preamplifier development 10 €/ channel 2 channels on one hybrid Custom-made front-end charge preamp + shaper Inspired from C. Boiano et al. IEEE Trans. Nucl. Sci. 52(2004)1931 • ICARUS electronics • (τf=1.6 μs) • S/N=10 @ 2 fC, Ci=350 pF • equivalent to S/N=7 @ 1 fC, Ci=200 pF

13. LEM-TPC Setup Preamplifier box F. Resnati PhD ETHZ in progress LEM-TPC typical signals and tracks Pure GAr Double-phase operation with unpurified LAr Signals digitized with one 8 channel, 14 bit, 100 MHz CAEN V1724 digitizer Signal fits and track reconstruction in progress: Diploma Work by A. Behrens, ETHZ

14. SY2791 R’EQUIP (130 kCHF) + ETHZ Scient. Equip. (130 kCHF) grants 64 channel prototype Data Acquisition System development • In collaboration with CAEN, developed A/D conversion and DAQ system 256 channels • 12 bit 2.5 MS/s flash ADCs + programmable FPGA with trigger logic • Global trigger and channel-by-channel trigger,switch to ’low threshold’ when a ‘trigger alert’ is present • 1 MB circular buffer, zero suppression capability, 80 MB/s chainable optical link to PC 32 preamplifier channels Tests in progress A/D + DAQ section ETHZ preamps CAEN SY2791 prototype CAEN A2792 prototype

15. 800 mm Funded by ETH + SNF ArDM: search for Dark Matter A. Rubbia, “ArDM: a Ton-scale liquid Argon experiment for direct detection of dark matter in the universe”, J. Phys. Conf. Ser. 39 (2006) 129 Two-stage LEM Cockroft-Walton (Greinacher) chain: supplies the right voltages to the field shaper rings and the cathode up to 500 kV (E=1-4kV/cm) Assembly @ CERN 1200 mm Field shaping rings and support pillars Cathode grid ETHZ, Zurich, Granada, CIEMAT, Soltan, Sheffield 14 PMTs

16. ArDM Inner Detector Field shaping rings and support pillars Cockroft-Walton (Greinacher) chain Cathode grid Reflector foils Shielding grid PMTs

17. ArDM Cryogenics and LAr purification vacuum insulation LN2 cooling jacket 1400 l ‘dirty’ LAr cooling bath pure LAr closed circuit Recirculation and CuO purification cartridge In collaboration with BIERI engineering Winterthur, Switzerland Bellow pump

18. ArDM Assembly Sept. 2007 – May 2008

19. Slow Control System Diploma Work by U. Degunda, ETHZ LAr Bath Levelmeters

20. temperature sensors along the detector axis ~ 20h refilling of the external bath Precooling of the external bath GAr @ 0.4bar Warming Up 9:00 6th May 16:00 8th May GAr @ 1.1bar 23:00 10thMay 04:00 13th May First ArDM cooldown

21. LAr Pump tests Diploma Work by L. Epprecht, ETHZ 30 cm3 volume In collaboration with BIERI engineering Winterthur, Switzerland  /  (# Measurement) Measured LAr flux ~ 20 l/hr

22. blue LED fiber movable 241Am source -30 0 +30 cathode e-shield photomultipliers First tests of Light Readout V. Boccone, PhD U. of Zürich in progress UHV magnetic actuator GAr @ 300K P=1.1bar 2~2.9s reflectors with wavelength shifter GAr @ 88K P=1.1bar 2~3.2s

23. The next steps … • LAr LEM-TPC tests with 32 channel readout and new CAEN DAQ system • implementation of LAr purification • simultaneous measurement of light and ionization charge • investigation of efficiency, stability and energy resolution of the LEM readout system • Address safety issues for ArDM: handling of one ton of LAr • installation of ODH detectors and in-situ rigeneration of the LAr purification cartridge • Filling of ArDM inner detector with LAr • operation of the LAr pump and purification cartridge • tests of light readout in LAr • test of the HV system • stability of cryogenic operation of the device: installation of a cryocooler • Design and construction of a 1 x 1 m2 LEM readout system for ArDM • Proceeding towards ‘physics’ operation of ArDM

24. Conclusions • The synergy between precise detectors for long neutrino baseline experiments and proton decay (and astrophysical neutrinos) apparatus is essential for a realistic proposal for a 50-100 kton LAr detector • discovery physics, not only precision measurements • GLACIER is a concept for a scalable LAr detector up to 100 kton demanding concrete R&D • ArDM is a real 1-ton prototype of GLACIER • After a successful demonstration of ArDM, we want to proceed in a staged approach in order to reach a mature proposal for a 100 kton device, possibly around 2014 • Full engineering design for a 1 kton prototype, together with continued R&D on readout devices/electronics • Construction of a 1 kton detector and exposure to a neutrino beam in a near location to demonstrate the physics performance