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CNGS-2

CNGS-2. Paola Sala, INFN Milano For the ICARUS collaboration. Can we compete with T2K and NOvA?. Baseline is the same as NO ν A  good energy range for event reconstruction (.. And we do not needd to redo all sensitivity/degeneracy… plots)

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CNGS-2

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  1. CNGS-2 Paola Sala, INFN Milano For the ICARUS collaboration Paola Sala

  2. Can we compete with T2K and NOvA? • Baseline is the same as NOνA  good energy range for event reconstruction (.. And we do not needd to redo all sensitivity/degeneracy… plots) • Beam energy is 3 times NUMI and 8 times K2K ; meson production scales almost linearly with beam energy: what matters is beam power , not protons on target AND • LAr performs better than Water and Scintillator • CERN accelerator complex and teams : super! Paola Sala

  3. Beam energy scaling Comparison of  ande event rates with the same optics, same off-axis position, for • 400 GeV/c proton beam • 120 GeV/c proton beam The ratio between event rates at 400 and 120 GeV primary energy (plotted) is around 2.5 in the region of interest (1-3GeV neutrino) Paola Sala

  4. Contents • The Off-axis concept (short!) • Off-axis with the present CNGS layout • Off-axis with an improved beam optics • Beam intensity For the CERN-GranSasso baseline : 732 km With the present CNGS beam momentum: 400 GeV/c Paola Sala

  5. Off-Axis Similar for K decay For an on-axis beam : E νμ= 0.43 Eπ Going to an angle θ : NOT for νe, that come from 3-body decay Paola Sala

  6. Optimum conditions At the CERN-GranSasso Baseline Assuming Δm223=2.5 10-3 eV2 • Oscillation max 1.5 GeV • 9< θ < 16 mrad  6-12 km off-axis Dependence of the  flux at angle θ on the parent pion energy: ( =Eπ/mπ) • Optics should focus low energy π • Intrinsic e background is also focused Paola Sala

  7. CNGS layout 800m 100m 1000m 26m 67m vacuum 10 s 50ms Proton beam from SPS, 400 GeV/c 2 fast extractions every 6 s Nominal intensity 2.4 1013 protons/extraction Nominal integrated intensity 4.5 1019 p.o.t./year in shared mode Paola Sala

  8. CNGS on-axis Paola Sala

  9. Standard CNGS Off-axis High energy , broad band optics Best efficiency around 7 km  broad peak, bad match of oscillation shape Paola Sala

  10. Towards a low energy optics • Low focus needs larger acceptance Emission angle vs. momentum for mesons produced in a 1m long C target by 400 GeV/c p pT=300 MeV/c Paola Sala

  11. CNGS target and target revolver Graphite 13 rods , spaced 4 or 5 mm diameter total length 2m C length  130 cm FOR LOW FOCUS: 1 m without spaces Paola Sala

  12. CNGS target/horn positioning Target – horn Distance : 120 cm (from end of last C bar) target horn TBID ( Target Beam Instrumentation Downstream) : User for alignment, can be replaced by already existent “BLM” ionization detectors Paola Sala

  13. Low energy optics Optimization in progress Preliminary layout: • Target • 1m long, graphite • No spaces • horn • NUMI-ME – like ( 3m long) • 200kA current, • at 20cm from target end • Reflector: • same position and outer dimensions as the CNGS one, • inner conductor redesigned for 15GeV focus, • 200kA current Paola Sala

  14. Off-axis with low energy optics Paola Sala

  15. Sensitivity vs. off-axis distance Event rates vs. Off-axis distance Energy limits : to optimize sensitivity Signal acceptance  90% Paola Sala

  16. Background rejection • Full simulation study • ( for an on-axis low energy beam) • Neutral Current background: • π0misidentification as electron • Suppressed by • - Topology, (  conversion far from vertex) • Reconstruction of the π0mass • electron/ photon separation based on dE/dx difference • Residual misidentification <0.1% • Electron identification efficiency = 90% •  NC background negligible with respect to intrinsic e Paola Sala

  17. Background rejection II • Distribution of dE/dx averaged over the first 2cm of • Electron tracks (green histo) • Photon from π0 decay (black histo) At 1 GeV. Low dE/dx in photon tracks comes mainly from Compton scattering events. Paola Sala

  18. Beam intensity • LAr/ other detectors : at least factor 3 in efficiency due to background reduction • Energy scaling • NOvA (numi) 6.5x1020 pot/y @ 120 GeV  < 1020 pot/y for ModuLAr • T2K 10x1020pot/y @ 50 GeV  < 1020 pot/y for ModuLAr Paola Sala

  19. Beam Intensity -II • Present CNGS : 4.5 1019 pot/y BUT: • Shared mode (fixed target experiments) • Assumed 55% efficiency for the accelerator complex • Intensity : 4.8 1013 pot/pulse • Period : 6 s • 1.4 1020 pot/y for 200 days 100% efficiency dedicated operation • order 1020pot/y is achievable without upgrades • Rates in the MODULAr proposal calculated for 1.2 1020pot/y Paola Sala

  20. Rates for 5 years, 20 kt and 1.2 1020 pot /year. Oscillation with sin2(213)=0.1. The upper integration limit, Elim, has been chosen to get the best sensitivity, S/√(bg). Paola Sala

  21. Further intensity upgrades • A further improvement of the CNGS beam performance could be envisaged increasing the proton beam intensity delivered to CNGS by the PS/SPS accelerator complex. 2 1020 pot/y are a realistic goal. • Further investigation are needed on possible limiting factors in the CNGS secondary beam line: • Target: the present target has been designed for a limiting intensity of 7.5 p/pulse ( vs 4.8 nominal). Thickness increase and beam spot widening will improve resistance (presently : 2-2.5 mm radius, 0.5 mm  beam spot.) • Hornheating : dominated by current, not by beam • Ventilation ? But equipments are in auxiliary tunnel, not in beam chamber… • Shielding ? Paola Sala

  22. Sensitivity to 13 GLoBES calculation 5% systematics 15% resolution Δm223=2.5 103eV2 Normal mass hierarchy CNGS low energy optics 20 kton 5 years 1.2 1020 pot/y 4.3 1020 pot/y Paola Sala

  23. T600 as control detector • There is no near detector at CNGS , however: • ICARUS T600 will be operational on-axis • Monte Carlo simulations provide e/ with few % systematics ( checked at WANF) • The on –off axis transformation is straightforward • A large fraction (60%) of off-axis e comes from π decay • On –axis,  can be measured in the 2<E <12 GeV interval, where the systematic error from oscillation parameters knowledge will be  2% This range accounts for 90 % of off-axis , and is an almost direct measurement of π generated intrinsic e background (60% of the total e ) • Off-axis, the K+ peak in the  spectrum is located above 10 GeV, where there is NO π contribution. This is an almost direct measurement of the K+ generatedintrinsic e background (24% of the total e ) Paola Sala

  24.  fluxes On Axis Off-axis Off-axiseflux  3000 CC events In MODULAr 5 y 1.2 1020 pot/y  3000 CC events In T600, 5 y 1.2 1020 pot/y Paola Sala

  25. Beam monitoring Beam monitoring at CNGS : • Particle multiplicity at target ( TBID+ ionization chambers ) • Muon monitors after beam dump optimized for an high energy optics Even with low energy focusing, There is a 50% excess of high energy muons over the non-focused beam These can be deyected at muon pit 1 Paola Sala

  26. Conclusions • The synergy between the CNGS beam and the LAr TPC technology is a bonus for 13 searches. • Assuming an off-axis 20 kton detector at 7-10 km from LNGS, the beam upgrades needed to compete with the next generation of LongBaseLine experiments are • New, low-energy, optics : target/horn/reflector modifications - mostly within the present external dimensions • Increase of the integrated beam intensity • without accelerator upgrades, “efficiency only” : the sensitivity is already better than the NOvA and T2K ones • With accelerator upgrades : the sensitivity scales approximately with the square root of integrated pot .. Paola Sala

  27. Black : out of target • Red : within 5mrad out of horn Paola Sala

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