Multi-Blade, a novel neutron detector Gábor Galgóczi MTA Wigner RCP of HAS REGARD group Outline ● European Spallation Source ● Thermal and cold neutron detection: – Techniques – Challenges at ESS ● The Multi-Blade detector ● Geant4 simulations: – Effect of neutron scattering quantified European Spallation Source (ESS) ● Novel concepts for neutron sources ● 17 European countries ● User programme starts 2023 ● Benefits: – manufacturing, pharmaceutical drugs – aerospace, engines, plastics – biotechnology Brightness of ESS How does ESS work? ● 17 European countries ● User programme starts 2023 LINAC for protons (2GeV) Samples W target How does ESS work? ● 17 European countries ● User programme starts 2023 ● Proton beam → Spallation → Neutrons – Moderator idea by Ferenc Mezei LINAC for protons (2GeV) ● Thermal and cold neutrons: Samples W target – ~meV (RHIC: ~GeV) How does ESS work? ● 17 European countries ● User programme starts 2023 ● Proton beam → Spallation → Neutrons – Moderator idea by Ferenc Mezei LINAC for protons (2GeV) ● Thermal and cold neutrons: Samples W target – ~meV (RHIC: ~GeV) ● Brightness: 30x state of. a. ● New detectors needed!! Instruments at ESS Neutron detection w. 3He ● n + 3He → 3H + 1H + 0.764 MeV ● Gamma-ray production → Needs to be surpressed ● Neutron capture x-section huge Neutron detection w. 3He ● n + 3He → 3H + 1H + 0.764 MeV ● Gamma-ray production → Needs to be surpressed ● Neutron capture x-section huge ● Main source: nuclear weapons programme https://fas.org/sgp/crs/misc/R41419.pdf Neutron detection w. 10B ● 10 B in B4C ceramic ● Alpha and Li ions are detected in MWPCs ● Dealing with high flux with a high grazing angle C 4 B neutrons 0 10 4C 1 neutrons B θ θ q q = 90 degrees = 5 degrees Efficiency 45% at 2.5Å Efficiency <5% at 2.5Å The Multi-Blade ● Usage: – At ESS: FREIA and ESTIA reflectometers ● Requirements: – High rate capability: 105 mm-2s-1 – Spatial resolution (4x0.5 mm) – Max. window scattering: 10-4 F. Piscitelli, F. Messi et al., The Multi-Blade Boron-10-based neutron detector for high intensity neutron reflectometry at ESS, Journal of Instrumentation 12, P03013 (2017) The Multi-Blade ● Usage: – At ESS: FREIA and ESTIA reflectometers ● Requirements: – High rate capability: 105 mm-2s-1 – Spatial resolution (4x0.5 mm) – Max. window scattering: 10-4 ● Geant4 simulations: – To understand scattering in the complex geometry F. Piscitelli, F. Messi et al., The Multi-Blade Boron-10-based neutron detector for high intensity neutron reflectometry at ESS, Journal of Instrumentation 12, P03013 (2017) The Multi-Blade ● Usage: – At ESS: FREIA and ESTIA reflectometers ● Advantages: – Spatial resolution: ● 2.5 mm x 0.5 mm ● 3 times state of the art The Multi-Blade ● Usage: – At ESS: FREIA and ESTIA reflectometers ● Advantages: – Spatial resolution: ● 2.5 mm x 0.5 mm ● 3 times state of the art – Max instantaneous rate: – 100 - 500 kHz / mm2 – 10 – 100 times state of the art The Multi-Blade ● Usage: – At ESS: FREIA and ESTIA reflectometers ● Advantages: – Spatial resolution: ● 2.5 mm x 0.5 mm ● 3 times state of the art – Max instantaneous rate: – 100 - 500 kHz / mm2 – 10 – 100 times state of the art – Neutron scattering? Detection process B4C sample (0,0,0)n θ substrate (Al, Ti) B4C sample α (0,0,0)n θ 7Li B4C sample (0,0,0) n α θ 7Li substrate (Al, Ti) conversion point in B 4C B4C sample (0,0,0) n α θ 7Li substrate (Al, Ti) detection point approximation (hit) conversion point in B 4C Neutron scattering detection point (hit) flat sample (0,0,0) w o d n i α w e c 7 ideal conversion n Li a point (geantino) in same B C volume r 4 t n as detection point 21 e y y’ Entrance window coordinate system, rotated wrt to global to be perpendicular to the incoming neutrons Z Z’ Results of the simulations ● Scattering with: – diff. window thicknesses – diff. neutron wavelengths – diff. Boron thicknesses – Etc. G. Galgoczi, K. Kanaki et al., Investigation of neutron scattering in the Multi-Blade detector with Geant4 simulations, Journal of Instrumentation (accepted, not yet published) Results of the simulations ● Scattering for: – diff. window thicknesses B4C α n 7 y θ Li Z G. Galgoczi, K. Kanaki et al., Investigation of neutron scattering in the Multi-Blade detector with Geant4 simulations, Journal of Instrumentation (accepted, not yet published) Results of the simulations ● Scattering for: – diff. window thicknesses – diff. neutron wavelengths B4C α n θ 7Li Z G. Galgoczi, K. Kanaki et al., Investigation of neutron scattering in the Multi-Blade detector with Geant4 simulations, Journal of Instrumentation (accepted, not yet published) Results of the simulations ● Scattering for: – diff. window thicknesses – diff. neutron wavelengths – diff. Boron thicknesses – etc. B4C α n θ 7Li Z G. Galgoczi, K. Kanaki et al., Investigation of neutron scattering in the Multi-Blade detector with Geant4 simulations, Journal of Instrumentation (accepted, not yet published) Summary ● European Spallation Source (ESS) is the world's next generation spallation-based neutron source ● Challenges for neutron detectors ● Multi-Blade neutron detector ● ~ 10-4 misplaced detections due to scattering ● Effect of scattering on the window (0.5 mm) satisfies the requirements Neutron detection ● 3He: – Price increased – Limited detection rates ● Novel technologies: – LiCaAIF6 – BF3 – 10Boron – Gadolinium .