BENE Introduction to ISS detector WG Pasquale Migliozzi INFN – Napoli

Mandate of the WG (A.Blondel at the ISS-KEK meeting) Evaluate the options for the neutrino detection systems with a view to defining a baseline set of detection systems to be taken forward in a subsequent conceptual-design phase. Provide a research-and-development program required to deliver the baseline design  Funding request for three years of detector R&D Some difficult choices will have to be made in order to most efficiently utilize the R&D resources that “might” become available

Working groups Water Cerenkov Detectors Kenji Kaneyuki, Jean-Eric Campagne Magnetic Sampling Detectors Jeff Nelson, Anselmo Cervera Liquid Argon TPC Scott Menary, Andreas Badertscher, Claudio Montanari, Guiseppe Battistoni (FLARE/GLACIER/ICARUS’) Emulsion Detectors Pasquale Migliozzi Near Detectors Paul Soler

Water Cerenkov

The MEMPHYS Project 65m Fréjus CERN 130km 4800mwe Excavation engineering pre-study has been done for 5 shafts Water Cerenkov modules at Fréjus CERN to Fréjus Neutrino Super-beam and Beta-beam

Main results of the preliminary study the best site (rock quality) is found in the middle of the mountain, at a depth of 4800 mwe of the two considered shapes : “tunnel” and “shaft”, the “shaft (= well) shape” is strongly preferred Cylindrical shafts are feasible up to : a diameter  = 65 m and a full height h = 80 m (≈ m 3 )  tons of water (4 times SK) taking out 4 m from outside for veto and fiducial cut  tons fiducial target 3 modules would give 440 kilotons (like UNO) BASELINE 4 modules would give 580 kilotons (HK) with “egg shape” or “intermediate shape” the volume of the shafts could be still increased The estimated cost is ≈ 80 M€ X Nb of shafts

Photodetectors Baseline: photomultipliers AIM: get the highest possible coverage to get the lowest possible threshold. Ideally, the same light/MeV as SuperK The 20”PM is to expensive (12.6€/PE) compared with the 12”PM (7.7€/PE). The latter has also the advantage of a better timing and position resolution Ongoing R&D on HPD together with PHOTONIS Ongoing R&D for electronics (ASIC’s) and mechanics AIM: low cost 200€/channel

A possible schedule for MEMPHYS at Frejus Year Safety tunnel Excavation Lab cavity Excavation P.S Study detector PM R&DPMT production Det.preparation InstallationOutside lab. Non-acc.physics P-decay, SN Superbeam Construction Superbeam betabeam Beta beam Construction decision for cavity digging decision for SPL construction decision for EURISOL site

SUPERBEAM BETABEAM  → e e →   Superbeam + beta beam together 2 ways of testing CP, T and CPT : redundancy and check of systematics 2 beams 1 detector 2yrs 8yrs 5yrs pure4 flavours + K     Recently a study on SB + BB + Atmospheric Neutrinos became available (see next)

The T2HK project Tunnel-shaped cavity Avoid sharp edges. Spherical shape is the best Twin cavities M FD /M TOT worse than single cavity. But… Two detectors are independent. One detector is alive when the other is calibrated or maintained Staging approach is possible The Tochibora mine is considered as a candidate site: very good rock quality Photosensors: PMT long-term stability proven, but too expensive. 13” HPD prototype under test at Tokyo U. Long term stability is an issue Photosensors: time production too long. How to reduce it?

Possible experimental set-up JPARC Off-axis angle 2.5deg.off-axis Distance from the target (km) 2.5 deg. off axis Total cost must be similar to the baseline design.

NB about 300 Oku-Yen should be included for the beam upgrade

Physics Reach of WC projects T2KK is not shown, but it improves the sensitivity to mass hierarchy The ATM neutrinos are for free and should always be used in the calculations!!! For the MEMPHYS project the results are good, but could be excellent if both SPL and BB (plus ATM data) are exploited: COSTS!

Summary table Reach (costs M€) SPL+ATM ( ) BB+ATM ( ) T2HK+ATM ( ) Θ 13 ****** δ CP ****** Mass hierarchy ****** Octant |sin 2 θ |>0.07 ** |sin 2 θ |>0.09 * |sin 2 θ |>0.05 *** These results have been obtained assuming equal systematic errors (2%) NB The goal of a 2% sys error with a conventional beam is very ambitious. Detector Accelerator

My comments The physics reach of WC detectors is well advanced and based on the solid bases of previous successful projects. Furthermore, it is very wide (SPL and/or BB, ATM, Solar, SN, proton decay,…) Assuming the availability of the needed budget and no correlation with the T2K/Nova results, 2020 seems to be a realistic date for the start of data taking. In case of correlation a 5 years delay is possible. Given that ATM neutrinos are for free and help a lot in solving degeneracies, it is mandatory to include them in all calculations An issue is the R&D on photodetectors: Costs should be reduced. HPD are promising. For the time being the better PE/MeV cost is given by 12” PMT Production rate should be optimized. At present it lasts 10 years the production of all PMTs for 1Mton detector. Storage space could become a problem MEMPHYS project: it seems that once the ATM are included the SPL performs better than BB (assuming equal sys errors. Optimistic?). Maybe the BB adopted for the Frejus is not the optimal choice. Of course SPL+BB gives superior performances but it is very expensive.

Segmented magnetic detector

Magnetic field Has not been investigated in any detail yet Considering two options: Iron sheets in between scintillator layers. Parameters to study are thickness of each sheet and ratio of scintillator to iron. More work needed to understand how to accurately simulate the field and perform reasonable reconstruction. Air toroid magnet surrounding detector. ATLAS magnet is a starting point in terms of scale. Simulating 0.15 T field to start. Will study physics parameters (P resolution, charge ID, etc) as a function of magnetic field

meeting Past month spent in code development and testing. Simulation now at a stage where they can be used for production of a high statistics sample for serious analysis. Reconstruction still requires some work to fine tune track fit. Need to define a list in order of priority of conditions to study and what results are required. First list looks like: Momentum resolution Charge identification Particle ID (dE/dx) Two track separation Jet angle and total energy resolution Hadronic response Neutron detection

Caveat (from A. Bross talk) Pattern recognition is “perfect” (or cheating!) as I use Monte Carlo truth to select the hits that belonged to the primary track (100% purity and efficiency). Once hits are selected, clustering, space point and track reconstruction proceed without the use of Monte Carlo truth information. Simple digitisation at the moment. Will need to decide what readout technologies to study in order to chose more appropriate values.

Is this Detector Scenario Credible? Technology is not really an Issue COST IS Assume a 25kT all scintillator detector with air-core magnet (B = 1-3 kG) Of course the study will also include magnetized Fe Much larger Fiducial mass Or could add non-active target in air-core design Scintillator (Solid or Liquid) – No R&D issues Cost (solid) - $100M Segmentation as shown here gives » 7 X 10 6 ch $10/ch is possible - $70M Fiber Cost – Assume high QE PD and high yield scint. Use 0.4mm fiber $0.16/m ~ $16M (Very important optimization – 1 mm fiber is 6X the cost!) $100M for magnets + infrastructure, etc Total is something less than $300M Not an order of magnitude more than what is acceptable

R&D areas Photo-detectors Already good work progressing on SiPM, MRS, even VLPCs. Need High QE and reasonable gain Potential readout chips already exist (integration) Scintillator Technology in place for the most part Co-extrusion of WLS fiber with scintillator Adjust plastic density (Z) by adding heavy element Optimization of Scint+WLS fiber + PD Cost/(pe detected) Magnets Natural extrapolation from Atlas? Assembly and integration Mild extrapolation from existing detectors But some significant cost savings with new engineering approaches in a number of areas

My comments The MC digitization should be developed according to the readout technology A realistic pattern recognition has to be developed in order to address the reconstruction issues The issue of how to magnetize the detector volume has to be addressed. This could be done together with the Emulsion WG although they need at least 0.5 T This detector technology is ONLY suitable for the study of the “golden channel” In the case of a “full active” detector, is it possible a synergy with the MECC technique? (see L.S. Esposito talk) The cost is not an issue, but a more solid estimate should be performed

An ideal detector for a NuFact should Identify and measure the charge of the muon (“golden channel”) with high accuracy Identify and measure the charge of the electron with high accuracy (“time reversal of the golden channel”) Identify the  decays (“silver channel”) Measure the complete kinematics of an event in order to increase the signal/back ratio A magnetic field is needed! Two possible technologies: Liquid Argon TPC Emulsion Cloud Chamber

industrial study of large Tank 70 m diameter, 20 m drift = 100 kton of Larg shown to be feasible conceptually The LAr TPC

Thanks to A. Rubbia

My comments Intensive R&D program going on The proof of the long drift is a crucial milestone (in progress) A detailed (magnetic, mechanical, thermal,…) of the coil yet to be performed Very important the success of the proposed staged approach: 1 kton → 10 kton → 100 kton Combine the efforts of the European and US communities Full event reconstruction of neutrino events has to be shown: important to show the efficiency and background as a function of the neutrino energy Define the needed magnetic field in order to efficiently (how much is driven by physics) measure the electron charge

MECC: the OPERA experience The detector is being constructed at the Gran Sasso Laboratory. Meanwhile several tests with charged particles and neutrinos at FNAL are under way An ECC brick is a self-consistent object. The whole detector is just an ensemble of bricks.

“MECC” structure DONUT/OPERA type target + Emulsion spectrometer + TT + Electron/pi discriminator Assumption: accuracy of film by film alignment = 10 micron (conservative) 13 lead plates (~2.5 X 0 ) + 4 spacers (2 cm gap) (NB in the future we plan to study stainless steel as well. May be it will be the baseline solution: lighter target) The geometry of the MECC is being optimized Stainless steel or LeadFilmRohacell B=1T 3 cm Electronic detectors/ECC

Momentum and charge measurements

Questions raised during the Study the MECC performances by considering a lower magnetic field (< 1 T) Optimize the target geometry and provide a reasonable estimate of the maximum affordable mass Propose a baseline for the electronic detector (NB it should not provide accurate points, it serves only as time stamp) Provide the energy dependence of the signal and of the background rates

My comments (details will be given by L. Esposito) The emulsion scanning and the reconstruction programs are being developed by the OPERA Collaboration It is possible to achieve the performances shown at the ISS-KEK meeting by using a 0.5 T magnetic field (the magnetization is similar to the one under study for the segmented magnetic detector: synergy) How to magnetized a very large volume? Given the expected interaction rate in each brick, a coarse electronic detector is enough (interesting synergy with the segmented magnetic detector) Good results not only in the momentum and charge measurement for mip, but also for electrons The needed R&D, but for the magnetic field, is not a real issue: a single brick is a self-consistent detector

e ±,  ±,  ± The R&D on the different detector techniques is in progress The main issue is “how to magnetize large instrumented volumes” Exploit as much as possible the synergy among different techniques (i.e. MECC and segmented magnetized detector) Realistic estimates of the signal and background as a function of the neutrino energy Realistic cost estimate not only of the detector but also of the accelerator complex

Near detector (taken from A. Blondel Set-up a generic simulation of a near detector Define a series of potential detector geometries to run on near detector -- dedicated purely-leptonic detector for absolute fluy -- quasi-elastic, pi, pi0 detector with variable targets (a la T2K ND280) -- charm detector for Nufact Carry out physics studies needed for the ISS report: 1. Study flux normalisation through: 2. Use quasi-elastic and elastic interactions to determine neutrino spectrum 3. Reconstruct muon polarization from spectrum 4. Sensitivity for cross-section measurements: low energy? 5. Determination of charm: remember this is main background for golden channel! 6. ….suggestions ….

Conclusion Systematics are a crucial issue. They seem to be the critical parameter in comparing “conventional beams” and BB operating with a 1Mton detector. Extremely important also at a NuFact The water Cerenkov performances are solid, being based on real data provided by several experiments Gigantic LAr detectors need a proof of principle: many activities under way The technology for a segmented magnetized detector is not an issue. More simulation and a more realistic reconstruction program are needed to assess the physics reach The MECC technique profits of the ongoing activity for the OPERA experiment. Possible (an welcome) synergy with other techniques for the electronic detector How to magnetize large volumes and which is the maximum achievable field is a crucial item. Depending on this item the physics reach of a NuFact can strongly change. E.g. if only a “standard” magnetized iron detector is feasible, only the golden channel can be exploited!

Outlook Study the performance of a stainless steel target Detailed study of the way how to magnetize the detector Define a realistic baseline for the e/  discriminator: its choice depends on the total target mass, the TT width (i.e. how many evts per brick), the costs, … Finalize the electron analysis: the e/  separation and the charge reconstruction Check the sensitivity to the “golden” (the muon threshold is at 3 GeV!) A full simulation of neutrino events is mandatory in order to evaluate the oscillation sensitivity and provide the input for GLOBES We plan to perform a first exposure of a MECC on a charged beam at CERN this year

considerable noise reduction can be obtained by gas amplification