Detector R&D: status and priorities Paolo Strolin NUFACT05 June 26, 2005 Low-Z Tracking Calorimetry Magnetised Iron Spectrometers Water Čerenkov Liquid Argon TPC Emulsion Cloud Chamber Main issues in launching the Scoping Study on a -factory and super-beam facility Some of the detectors also for astro-particle physics

To be carried out in parallel for detector optimisation Physics requirements Tests Monte Carlo evaluation of detectors’ performance: signal and backgrounds Detector R&D Detector design Comparisons and choices

”Where do we stand with (conceptual) beam-detector optimization for  -beams and -factory beams?” … was the main topic of the talk on Neutrino detectors for future neutrino beams by S. Ragazzi More work to be done Also emerged from WG reports and talks on specific detectors One of the issues is ….

-factories: searching for wrong sign muons More work to be done for detector optimisation ↓ Tune Monte Carlo on the basis of existing detectors Assume baseline design, in collaboration with engineers Simulate detectors Detector optimisation Compare different detector concepts and designs …..……….. Background from: - wrong charge assignment to leading muon: reduced with momentum cut and track fit cut -  from  -decay or from heavy quark decay: reduced with isolation cut (e.g. require minimum p t of the leading muon with respect to hadron jet) Momentum tracking threshold and resolution: affect sensitivity, degeneracy and possibility to lower E (talk by P. Huber)

This talk: Detector R&D: status and priorities Some of the progress which has been done Main issues on detector R&D and design (in partial overlap with WG reports)

Low-Z Tracking Calorimetry

NO A in off-axis NuMI beam Main issue: mass 10 x MINOS → new technologies to reduce cost  Observe  13  Liquid (plastic in MINOS) scintillator  Avalanche Photo Diodes (APD) (PMT’s in MINOS) higher QE → longer strips → less readout channels  Totally Active liquid scintillator Detector (TASD): now retained  No need of underground location (live-time ~100 s/year) Active shielding from cosmic rays foreseen (cheaper than passive overburden)  Detector to be completed in late 2011 if funding begins in late 2006 Main new technologies with respect to MINOS

The “totally active” NO A detector 30 kton mass: 24 kton liquid scintillator, 6 kton PVC 4-6 cm (x, y, z) segmentation Progress in the mechanical design and in the construction methods: details are taking shape Experience with trackers: potentially useful also for magnetised iron spectrometers

Magnetised Iron Spectrometers

A Large Magnetic Detector (LMD) for a Factory Iron calorimeter, plastic scintillator rods as active detector Magnetised at B = 1 T → see “wrong sign” muons from e -  Conventional technique, but 40 kton mass (one order of magnitude > MINOS) Only concept available: practical problems must be addressed to assess the feasibility (mechanics, magnet design, …. ); technical support needed More simulation work to be done to understand and optimise the performance

Making a torus bigger than MINOS From the talk by J. Nelson: “the detector is feasible” –large area toroidal fields can by extrapolated from MINOS design (thicker plates for large planes) –can now make an affordable large area scintillator readout with NOvA technology Engineering work must be done on mechanics, magnet design, …. Studies required to optimise the performance of the detector (tracking threshold, resolution, background rejection, e-ident, …) Make direct use of the experience with MINOS

A kton magnetised iron detector à la Monolith Monolith concept by P. Picchi and collaborators taken up for the India-based Neutrino Observatory (INO) (talk by N.K. Mondal) → atmospheric neutrinos, in future -factories Investigations started with Monolith to be taken up again: detector performance studies, comparison horizontal vs vertical iron plates, design optimisation, comparison with other detectors, …..

Water Čerenkov

Comparison of Hyper-K and UNO.vs. Super-K Super-KHyper-KUNO Total mass [kton]502 x Fiducial mass [kton]22.52 x Size  41 m x 39 m 2 x  43 m x 250 m 60 m x 60 m x 180 m Photo-sensor coverage [%]40 ⅓ 40 (5 MeV threshold) ⅔ 10 (10 MeV threshold) PMT’s11,146 (20”) 200,000 (20”) 56,650 (20”) 15,000 (8”) A large fraction ( ½ or more) of the total detector cost comes from the photo-sensors With present 20” PMT’s and 40% coverage for the full detector, the cost of a Mton detector could be prohibitive IMB / KamiokaNDE → Super-K → Hyper-K / UNO In each generation one order of magnitude increase in mass

Increasing the detector mass … better energy containment larger “effective” granularity of photo-sensors (due to larger average distance of photo-sensors from event vertex) Main issue R&D on photo-sensors, in collaboration with industries* to improve:  cost  production rate: affects construction time and may give serious storage problems  performance: time resolution (→ vertex), single photon sensitivity (→ ring reconstruction) * The development of 20” PMTs was fundamental for KamiokaNDE and Super-KamiokaNDE

R&D on photo-sensors for Water Čerenkov  PMT’s  Automatic glass manufacturing not the way to reduce cost and speed-up production rate: required quantities still small compared to commercial PMT’s  Collaboration with industries (Hamamatsu, Photonis, …. ) - very important for an effective R&D - competition could stimulate ways for cost reduction  Are 20” PMT’s optimal? Global cost PMT+glass sphere, risk of implosion, …  What is the optimal photo-sensor coverage? Function of physics, energy,..  New photo-sensors –Hybrid Photo-Detectors (HPD) by ICRR Tokyo - Hamamatsu –……. Long term stability and reliability are a must Proven for PMT’s

Simpler structure → lower cost no dynodes Single photon sensitivity from large gain at the first stage Good timing resolution (~1ns) PMT-SK: ~2.3 ns (mainly TTS) Wide dynamic range (>1000 p.e.) determined by AD saturation Challenging HV (~20 kV) → focus onto a small AD (5mm  ) Smaller Gain highly reliable low-noise amplification and readout needed Principle of HPD and comparison to PMT’s photocathode avalanche diode (AD) photon Bombardment Gain Total Gain ~10 5 Avalanche Gain ~30 or more HV photo electron ( p.e.) PMT-SK dynodes TTS (Transit Time Spread) Total Gain ~10 7 HPD

R&D on HPD’s Proof of principle achieved with 5” prototype New results: 13” prototype tested with 12 kV: gain 3x10 4, single photon sensitivity, timing resolution 0.8 ns (2.3 ns with PMT’s), good gain and timing uniformity over photo-cathode area Next steps: - new bulb: 12kV → 20kV, giving wider effective photo-cathode area and higher gain - higher gain from AD, low-noise preamp, readout 1st peak 2nd peak 0 p.e. 30,000 electrons 1 p.e. RMS 0.8 ns

An ancestor of hybrid PMT’s P.h. resolution: elimination of single p.e. noise (for DUMAND) Patented by Philips (Photonis) Copied by INR, Moscow: → the “QUASAR” Large investment by Philips/Photonis: made ~ QUASARs (15”) operating for many years in Lake Baikal No ongoing production Photo-cathode PMT scintillator photon photo electron 25 kV

Liquid Argon Time Projection Chamber Two target mass scales for future projects:  100 ton as near detector in Super-Beams (not discussed here)  kton for oscillation, astrophysics, proton decay

Cryogenic insulation requires minimal surface/volume → A single very large cryogenic module with aspect ratio ~ 1:1 Do not pursue the ICARUS multi-module approach Longer drift length, to limit the number of readout channels Two approaches: m drift length, with readout as in ICARUS 2. Very long drift length (~ 20 m) and “Double Phase” readout (amplification in Gas Argon to cope with signal attenuation) In both cases, the signal attenuation imposes a high LAr purity (~ 0.1 ppb O 2 equiv.) ICARUS T300 module: 0.3 kton, 1.5 m drift, ~1 ms drift time “The present state of the art” ICARUS: a ~ 2 kton detector to be operated underground at Gran Sasso To reach kton mass

Double-Phase (Liquid – Gas) readout Basic references: Dolgoshein et al. (1973); Cline, … Picchi... et al. (2000) Tested on the ICARUS 50 l chamber Charge attenuation after very long drift in liquid compensated By charge amplification near anodes in gas phase With 2 ms e-lifetime, the charge attenuation in 10 ms is e -t/  ≈ 1/150 (original signal 6000 e - /mm for a MIP in LAr) Amplification in proportional mode (x ) on thin wires (  ≈ 30  m) with pad readout or..… Diffusion after 20 m drift →  ≈ 3 mm : gives a limit to the practical readout granularity e-e- Ampl. + readout race track electrodes Liquid Ar Gas Ar Extraction grid

A Liquid Ar TPC for the off-axis NuMI beam Letter of Intent, hep-ex/ (2004) A detector for oscillation Readout as in ICARUS, with detector subdivided in readout sections kton : x10 2 extrapolation in mass from ICARUS T300 3 m max drift length (1.5 m in ICARUS T300) with E = 0.5 KV/cm Surface location foreseen (operated only with beam) Progress in the engineering design (talk by S. Pordes) HVHV S i g n a l

A 100 kton Liquid Argon TPC with “Double-Phase” readout A. Rubbia, Proc. II Int. Workshop on Neutrinos in Venice, 2003 A detector for oscillation, astrophysics, proton decay A single cryogenic and readout module 20 m drift length, 10 ms drift time with as much as 1 KV/cm (0.5 in ICARUS T300): Liquid Ar at boiling temperature, as for transportation and storage of Liquefied Natural Gas ~ 3x10 2 extrapolation in mass from ICARUS T300 Liq. Ar Cathode (- 2 MV) Extraction grid Charge readout plane Scint. (UV) and Č light readout by PMTs E ≈ 3 kV/cm Electronics racks Field shaping electrodes E ≈ 1 kV/cm Gas Ar p ≈ 3 atm  p < 0.1 atm 20 m drift

l Electron drift under high pressure (p ~ 3 atm at the bottom of the tank) l Charge extraction, amplification and imaging devices l Cryostat design, in collaboration with industry l Logistics, infrastructure and safety issues (in part. for underground sites) l Tests with a 5 m column detector prototype ● 5 m long drift and double-phase readout ● Simulate 20 m drift by reduced E field and LAr purity Study of LAr TPC prototypes in a magnetic field (for Factory): tracks seen and measured in 10 lt prototype Ongoing studies and R&D (from A. Rubbia)

First operation of a 10 litre LAr TPC in a B-field (talk by A. Rubbia) 150 mm First real events in B-field (B=0.55T), New J. Phys. 7 (2005) 63

Tentative layout of a large magnetized Liquid Argon TPC (talk by A. Rubbia) Liq Ar Cathode (- HV) Extraction grid Charge readout plane UV & Cerenkov light readout PMTs and field shaping electrodes E≈ 1 kV/cm E ≈ 3 kV/cm Electronic racks Gas Ar B≈ 0.1  1 T Magnet: solenoidal superconducting coil Two phase He LHe LHe Cooling: Thermosiphon principle + thermal shield = LAr Phase separator He refrigerator

The Emulsion Cloud Chamber (ECC) for e →  appearance at Factories e →  (golden events) and e →  (silver events) to resolve  13 -  ambiguities Pb as passive material, emulsion as sub-  m precision tracker: unique to observe  production and decay Hybrid experiment: emulsion + electronic detectors 1.8 kton OPERA target mass → ~ 4 kton at Factory Scan events with a “wrong sign” muon: x 2 increase of scanning power required OPERA is a milestone for the technique The OPERA detector (~200,000 bricks) “Brick” (56 cells, 9 kg) 8 cm (10X 0 ) Basic “cell” Pb 1 mm Emulsion

Summary (1): Low-Z Calorimetry   - e  oscillations →  13 in off-axis NuMI beam: NO A  Evolution of a proven technique  Main issue: improve performance and reduce cost of trackers  NO A: mass ~ 10 x MINOS  New technologies with respect to MINOS plastic → liquid scintillator: a totally active detector now chosen PMT → Avalanche Photo Diodes (APD)  Progress on trackers potentially useful also for magnetised iron sampling spectrometers or for calorimetry in view of other applications (maintain contacts with the collider community)

Summary (2): Magnetised Fe Spectrometers  “Wrong sign”  from e  →  oscillations at -Factories  Well proven technique  Target mass ~ 10 x MINOS  Proceed from concepts towards a design Engineering work (mechanics, magnet design, …. ) must be done to assess the feasibility; technical support needed Evaluate and optimise the performance of the detector (tracking threshold, resolution, background rejection, e-ident, …) → detailed detector simulations

Summary (3): Water Čerenkov  oscillation, astrophysics, proton decay  Proven and successful technique, well known also in its limitations Super-K: a large Water Čerenkov detector of which the performance has been simulated and observed  Experience with experiments: K → Super-K → Hyper-K/UNO/Frejus: in each step mass x ~10  Main issue: cost and production of photo-sensors → collaboration with industries: very important, to be supported → are 20” PMT’s optimal? Which is the optimal photo-sensor coverage? → R&D on new photo-sensors with adequate long-term stability&reliability

Summary (4) : Liquid Argon TPC  A beautiful detector for oscillation, astrophysics, proton decay. Broad energy range  Tested at the scale of the 0.3 kton ICARUS T300 module: extrapolation in mass by two orders of magnitudes or more needed  New features envisaged to reach kton: longer or much longer drifts, double-phase amplification and readout  Experience accumulated for ICARUS, dedicated R&D (results now available from 10 liter chamber in magnetic field, …)  Substantial R&D required on various aspects, partly depending on the design parameters: signal propagation and readout, HV and electric field shaping; cryogenics, purification, operation in a magnetic field, civil engineering, safety and logistics, …..  Proceed from concepts towards detector designs (without and with magnetic field)  Location: underground (availability and cost, more severe safety issues) or surface location (assess if adequate: loss of events superimposed to cosmics)

General conclusions Very interesting times for the scoping study and for the future of neutrino physics Work done by groups and collaborations Requires support by the respective institutions The scoping study will provide an important framework to exchange knowledge, device strategies and best collaborate Establish interactions with R&D for other purposes, e.g. for linear collider physics A lot of work is going on