A cold neutron beam facility for particle physics at the ESS Torsten Soldner Institut Laue Langevin ANNI Proposers: H. Abele, TU Wien G. Konrad, TU Wien & SMI Wien B. Märkisch, TU München U. Schmidt, Uni Heidelberg T. Soldner, ILL Grenoble C. Theroine, ESS Lund Aerial view ESS construction site September 2016

Cold beam facility for particle physics at ESS Advantages of the a Long pulse source  high flux Low repetition rate (14 Hz)  later frame overlap First pulsed source with same time-averaged flux as the ILL(or even higher with final moderator design)  We want a beamline there! SPP 1491 – Nov 2015 Cold beam facility for particle physics at ESS

Statistics or Systematics?? Count rate: 400/s Perkeo II Fight against beam-related background PSI2016 Cold beam facility for particle physics at ESS

Statistics or Systematics?? Count rate: 400/s Perkeo II 40000/s Perkeo III Beam-related background! Spectrometer response? PSI2016 Cold beam facility for particle physics at ESS

Statistics or Systematics??  Statistics or Systematics?? Statistics and Systematics! Count rate: 400/s Perkeo II 40000/s Perkeo III 400/s Perkeo III pulsed 4000/s Perkeo III pulsed at ANNI See C. Roick (poster) No beam-related background Well-defined spectrometer response PSI2016 Cold beam facility for particle physics at ESS

Pulsed beams: Statistics and Systematics! Spatial localization of neutron pulse Separation of beam-related background Separation of undefined spectrometer response Time localization of neutron pulse Signal/background Suppression of background and drifts with different time constant Separation by neutron wavelength Velocity dependence of signal and systematics Loss-free monochromatization Time-dependent neutron optics Wavelength-specific optics adapts to all neutrons See F. Piegsa (next talk) PSI2016 Cold beam facility for particle physics at ESS

Science case Neutron beta decay with 10-4 accuracy Broad-band probe for physics beyond the standard model, at scales of 1-100 TeV LoI by K. Bodek: Neutron decay correlations with BRAND Absolute measurements in hadronic weak interaction Systematic experimental study of QCD in non-perturbative regime LoI by C. Crawford: Weak interactions between nucleons New approaches to electromagnetic properties of the neutron Beam methods for EDM and charge as probe for matter creation and unification of forces LoI by F. Piegsa: Neutron EDM by beam method Project open for you! More science very welcome! For details, see this conference PSI2016 Cold beam facility for particle physics at ESS

Design considerations Maximum statistics at minimum systematics for versatile user instrumentation Fully exploit pulse structure Include polarization Assure low background Include ep/n separator Optimize for beam quality Provide flexibility PSI2016 Cold beam facility for particle physics at ESS

Length of instrument  Short instrument: Maximum statistics No frame overlap for high-intensity part of spectrum Limit dilution of neutron pulse Fully exploit pulse structure  Short instrument: 14 Hz ESS, 8 Å  maximum length 34 m (maximum ≡ neutrons leave experiment!) Low background from source Good wavelength resolution Space to neighbors PSI2016 Cold beam facility for particle physics at ESS

Cold beam facility for particle physics at ESS ANNI – Overview Moderator Guide Beam preparation Experimental area Extension area 34 m 12 m 20 m PSI2016 Cold beam facility for particle physics at ESS

Guide Concept Short guide 2 × out of sight Strong curvature Benders 20 m 2 × out of sight Strong curvature Benders 20 m S-shape in vertical plane, because of moderator and polarization Details optimized by McStas simulations for reference experiments Element Dist [m] Radius Length Cross-section [mm2] # m value γ* [mrad] λ* [Å] Trumpet 2.0 ∞ 3.6 88×60117×60 1 3.5 / 3.0 Straight 1 5.6 0.9 117×60 3.0 Bender 1 6.5 270 8.0 2 3.0, B: 3.5 14.7 2.44 Straight 2 14.5 0.4 Bender 2 / Polarizer 14.9 –84 2.5 6 3.0, T: 3.5 Anti-trumpet 17.4 4.6 117×60112×70

Cold beam facility for particle physics at ESS Polarization options Moderate polarization (98%) at highest intensity Bender 2 replaced by Polarizing bender Highest polarization (>99.9%) Polarizing bender + bender in beam preparation area in X-SM geometry Polarization with analytic wavelength dependence 3He spin filter in beam preparation area X-SM bender or 3He cell Polarizing bender PSI2016 Cold beam facility for particle physics at ESS

Versatile chopper system Highest intensity without frame overlap Localization in Time or in Space Monochromatization Pulse multiplication Dist [m] Radius [cm] Frequency [Hz] Angle [º] Comment PDC1 6.5 40 14—70 Variable 2 co-rotating disks FOC1 14 64 Single disk FOC2 8.5 79 PDC2 26 PSC 60 PMC Different slits 2 counter-rotating disks, replacing the disks of the PDC2 PSI2016 Cold beam facility for particle physics at ESS

Cold beam facility for particle physics at ESS Chopper modes Full intensity: Choppers off Maximum intensity without frame overlap: Only FOCs Time localization: PDC2 large opening + FOCs Monochromatic: PDCs small opening @ 70 Hz + PSC + FOCs Spatial localization: PDCs small opening @ 70 Hz + PSC + FOCs or pulse multiplication + FOCs Frame overlap suppression until130 Å Resolution at 8.9 Å: 0.55 Å FWHM PSI2016 Cold beam facility for particle physics at ESS

Example: Pulse multiplication with PERC  Example: Pulse multiplication with PERC fmax 70 Hz > 14 Hz of ESS PMC PSI2016 Cold beam facility for particle physics at ESS

ep/n separator as integral option Available to all users Fully optimized for ESS Two detectors for improved systematics (stability monitoring, backscattering) Profits from experience with PERC Wien filter for protons Electron detector Electrostatic chopper & p detector Magnetic spectrometer MAC-E filter R×B spectrometer See aSPECT (talk & posters) See G. Konrad (poster) User monitor User instrument B

Cold beam facility for particle physics at ESS Performance Parameter Value Capture flux full spectrum 5.4·1010 n/(cm2s) at guide exit 1.8·1010 n/(cm2s) at start of experimental area Capture flux 2—8 Å (FOCs) 4.0·1010 n/(cm2s) at guide exit 1.4·1010 n/(cm2s) at start of experimental area Particle flux @ 8.9 Å 5.8·108 / (cm2sÅ) at start of experimental area (with additional guide in beam definition area) Divergence distribution FWHM 42 mrad horizontal 22 mrad vertical Instantaneous bandwidth 0.43 Å PSI2016 Cold beam facility for particle physics at ESS

Gain Signal / Background World leading from 1 MW ESS power Benchmarks Experiment Facility Gain Event rate Gain Signal / Background Comment NPDGamma FnPB (SNS) 15 1 Wavelength information PERC MEPHISTO (FRM II) 17 34 Pulse localization in spaceA With PMCA PERKEO III PF1B (ILL) 6 16 Pulse localization in space With PMC aSPECT 0.4 3 10 Pulse localization in time at ANNI only BeamEDM 25 Wavelength information, time dependent optical elements World leading from 1 MW ESS power PSI2016 Cold beam facility for particle physics at ESS

Cold beam facility for particle physics at ESS Status and Outlook Not hopeless. See info session this evening PSI2016 Cold beam facility for particle physics at ESS

Cold beam facility for particle physics at ESS Summary Pulsed beams extremely useful for particle physics Separation by wavelength Time and spatial localization of pulse Cleaner systematics ESS has ideal time structure & brightness Full beamline design and simulated performances: ANNI will outperform all existing cold beam lines for particle physics, by 1-2 orders of magnitude Need joint effort from community for realization ↖    PSI2016 Cold beam facility for particle physics at ESS