A Short Baseline Neutrino facility (SBLNF) in the CERN NORTH AREA: Design overview

8th INTERNATIONAL WORKSHOP ON NEUTRINO BEAMS & INSTRUMENTATION NBI2012 – 6th/10th November 2012 A Short Baseline Neutrino facility (SBLNF) in the CERN NORTH AREA: Design overview M. Calviani, I. Efthymiopoulos, A. Ferrari, B. Goddard, R. Losito, J. Osborne, P. Sala, L. Scibile, R. Steerenberg, H. Vincke

Outline • Introduction to the Short Baseline Neutrino Facility Study Group • Experimental requirements • Preliminary parameters of the installation • Proto-layout of the installation • Neutrino production area configuration • Open points and challenges • Conclusions M. Calviani et al., Short Baseline neutrino facility (SBLNF) design overview

Introduction to the Short Baseline Neutrino Facility Study Group • Experimental requirements • Preliminary parameters of the installation • Proto-layout of the installation • Neutrino production area configuration • Open points and challenges • Conclusions M. Calviani et al., Short Baseline neutrino facility (SBLNF) design overview

SBLNF study group • A SBLNF study group has been convened to address the feasibility of a short baseline neutrino facility in the CERN North Area • This should serve primarily the ICARUS/NESSiE experiment (C. Rubbia et al., SPSC-P-347) as well as a neutrino test area for detector R&D and neutrino cross-section measurement • Why not use CNGS? • Target area very deep (~60m), too costly to install new detectors underground • DP configuration not adapted for a low energy neutrino beam M. Calviani et al., Short Baseline neutrino facility (SBLNF) design overview

Experimental requirements • Sterile neutrino physics (C. Rubbia et al., SPSC-P-347): • Exploring the possible existence of one or more sterile neutrino • Search for spectral differences of electron-like specific signatures in two identical detectors at two different neutrino decay distances • An exact proportionality between two ne spectra implies absence of neutrino oscillations • 1600 m: ICARUS T600 detector + magnetic spectrometer (NESSiE) • 350 m: new 150 LAr-TPC detector + magnetic spectrometer (NESSiE) nm+anti-nm ne+anti-ne M. Calviani et al., Short Baseline neutrino facility (SBLNF) design overview

Preliminary parameters of the installation • 100 GeV/c beam momentum • Neutrino spectrum peaked at ~2 GeV • ND at 350 meters, FD at 1600 meters, middle position detector at ~700 meters from target • DP: length ~80-120 m, radius 100/200 cm • DV of 100 meters is the experiment minimum requirement • Hadron absorber: • Graphite core, 2-3 meters long, 1x1 m2 surface • Segmented Fe blocks (10/18 meters in total) • Beam line at around 10/15 meters from “ground” M. Calviani et al., Short Baseline neutrino facility (SBLNF) design overview

CERN accelerator complex SBLNF M. Calviani et al., Short Baseline neutrino facility (SBLNF) design overview

Primary beam configuration • 100 GeV/c baseline primary beam momentum • 3.5*1013 p/pulse (4.5*1013 p/pulse ultimate running) • 6s (3.6s min) repetition rate • ~100 kW (200 kW) beam power • Time sharing between fixed-target physics  Yearly POTs between ~3-4.5*1019 p+/yr • New extraction lines from existing tunnels • Beam 1s on target: 1-2.5 mm, divergence ≤1 mrad M. Calviani et al., Short Baseline neutrino facility (SBLNF) design overview

Beam extraction from SPS • Fast extraction not available in the SPS North Area branch (complex to install a new kicker in a short time) • Beam excitation via injection kicker in LSS1 + extraction via existing septa • Solution tested for low intensities during recent beam tests Short baseline neutrino beam Magnetic septa (MST+MSE) slow Injection kicker (MKP) B. Goddard M. Calviani et al., Short Baseline neutrino facility (SBLNF) design overview

Far detector ~1.6 km • Beam line ~parallel to the existing North Area lines • New production infrastructure • Experiments and neutrino beam test areas Testing area for new generation detectors Near detector ~350 meters Target area M. Calviani et al., Short Baseline neutrino facility (SBLNF) design overview

Muon fluence and constraints Decay pipe Hadron stopper Moraine soil • ND should be at least at 350 meter from target! M. Calviani et al., Short Baseline neutrino facility (SBLNF) design overview

Neutrino beam production area configuration • The baseline configuration of the target area inspired by both AP0/NuMI“chase” and T2K: • No direct personnel access close to production elements • Reduced number of equipment in hot zones • Remote maintenance on all equipment • Reduced air volume around the production elements • Allow for target volume and decay pipe under He environment (TS and DP separated in case of access) • Shallow depth calls for heavy shielding around target trench and decay pipe M. Calviani et al., Short Baseline neutrino facility (SBLNF) design overview

(Proto) layout of the installation (FLUKA) FLUKA preliminary implementation: Shielding thickness not optimized! Hadron stopper Target station building and vault Target chase Primary beam area Target shielding Decay pipe Decay pipe shielding Ground (moraine) M. Calviani et al., Short Baseline neutrino facility (SBLNF) design overview

(Proto) layout of the installation (FLUKA) Target station building and vault 200 cm He vessel (medium blue) Concrete shielding (red) 300 cm Target chase Iron shielding (dark blue) 300 cm Target & horn/reflector Ground (moraine) M. Calviani et al., Short Baseline neutrino facility (SBLNF) design overview

Absorber/m stations • Hadron absorber: • Effective iron length of 10/18 meters • Water cooling system (surface) • Muon pits (i.e., diamond-detectors): • Pit 1 inside the dump to be sensitive to low energy m (~5 GeV) • Pit 2 downstream the absorber • Access via a dedicated surface building M. Calviani et al., Short Baseline neutrino facility (SBLNF) design overview

Potential target configuration • CNGS target design • Cooling by radiative emission and partly by convective exchange • Graphite at high temperature (~1000 °C) • Revolver structure would have allowed to exchange remotely target without interventions M. Calviani et al., Short Baseline neutrino facility (SBLNF) design overview

Potential target configuration • SBLNF: CNGS-like “evolutionary” design • graphite/beryllium options under investigation • Simpler construction and more diagnostics • Complete remote manipulation • Possibility to have a closed He-loop cooling (enhanced convection) – external air blow could be avoided • Pressurized circuit with an external heat exchanger • No segmentation required by physics • Larger rod and beam radius (~4-10 mm radius) • Reduced off-axis vibration issues • Enhanced production of low energy p/K Preliminary design on-going M. Calviani et al., Short Baseline neutrino facility (SBLNF) design overview

Potential target configuration • For both solution the baseline is to have a passive or actively He-cooled target PROs & cons to be studied in detail M. Calviani et al., Short Baseline neutrino facility (SBLNF) design overview

Preliminary radioprotection aspects • Optimisation: annual dose <100 mSv for exposed personnel (<10 mSv for general public) • CERN dose limits: • 6 mSv/y or 20 mSv/y (for radiation workers), 1 mSv for other personnel working at CERN and 0.3 mSv/y for general public • Detailed studies to follow: • Required shielding (thickness, material choice) • Induced radioactivity (structure, surroundings, soil, groundwater) • Optimization of design to minimize intervention doses for maintenance personnel • Waste & decommissioning M. Calviani et al., Short Baseline neutrino facility (SBLNF) design overview

Preliminary radioprotection aspects • H*(10) with the current shielding: • In the target vault <10 mSv/h • Above DP, At 15 m from beam axis < 1 mSv/h • Values manageable with a proper shielding design PRELIMINARY M. Calviani et al., Short Baseline neutrino facility (SBLNF) design overview

Challenges in the design • He vessel for TS/DP: • Material/thickness? • He at atmospheric pressure? • Closed loop with recirculation? Purge system? • Constraints in He purity for a C/Be target? • Which shielding elements should be included in the vessel? • Separate volume via appropriate shutter (closed during access) to avoid purging the DP volume Several technical questions concerning the engineering of the installation are still open M. Calviani et al., Short Baseline neutrino facility (SBLNF) design overview

Challenges in the design • Target: • In case of a He-cooled target, shall we keep the target and He-vessel circuits separated? • How critical is the purity in the He-loop? • Shielding: • Inner iron layer water/air cooled (~50 kW deposited)? • Decay pipe inner layer shall be water cooled (T2K-like?) • Soil/water activation minimization: • Groundwater mobility for surface layers? • Careful design of the interface between activation zone and surrounding earth • Radioactive gas emission in the TS M. Calviani et al., Short Baseline neutrino facility (SBLNF) design overview

Conclusions • A study group has started addressing the technical feasibility of a short baseline neutrino facility in the CERN North Area • It would be a 100 GeV/c p+ beam, ~200 kW installation, at shallow depth (10/15 m) • Neutrino production area to be a “chase”-based design • Significant design efforts to be dedicated in 2013 to have it operational in the next few years Design experience from NBI colleagues will be precious, considering feedback from running installations (T2K/NuMI/NoVA) M. Calviani et al., Short Baseline neutrino facility (SBLNF) design overview

Backup M. Calviani et al., Short Baseline neutrino facility (SBLNF) design overview

(Proto) layout of the installation • Main target vault, housing: • Target/horn/reflector trench • Radioactive storage area • A temporary shielded area - fast inspection and “easy” repair • Annex service building: • general services and assembly M. Calviani et al., Short Baseline neutrino facility (SBLNF) design overview

Open points: TS energy deposition • Target: ~1.5 kW • “Chase” iron shielding: • ~50 kW deposited power • Air/He cooling necessary? • DP shielding: • ~68 kW on the first 50 cm layer  thermal cracking? • Mitigation strategy to be further investigated M. Calviani et al., Short Baseline neutrino facility (SBLNF) design overview

Layout considerations • The position of the target is constrained by: • Existing buildings • Bending radius of the extraction line • The near detector distance from target and existing buildings M. Calviani et al., Short Baseline neutrino facility (SBLNF) design overview

A Short Baseline Neutrino facility (SBLNF) in the CERN NORTH AREA: Design overview