Neutron Detection with CASCADE The synthesis of GEMs and Solid State Converters
Contents Conduct Construct
The Helium-3 crisis 2 9/11 Costs: 2000-3000 /L If you can get it Size of the Helium-3 Stockpile, 1990-2010 [1] [1] AAAS, Overview of Helium-3 Supply and Demand
Basic concept 3 Cross section: active detection volume [1] c c c c [1] [1] Sauli, F. ; Sharma, A.: Micropattern Gaseous Detectors. In: Annual Review of Nuclear and Particle Science 49 (1999)
About: Construct
CASCADE an overview 4 CASCADE detector without housing 200mm x 200mm
CASCADE an overview 4 CASCADE detector without housing Active Detection Volume Readout Electronics
CASCADE an overview 5 CASCADE detector without housing Active Detection Volume - Neutron conversion in Boron-10 10 B + n 7 Li + + 2.79 MeV ( 6%) 7 Li * + + 2.31 MeV (94%) - Charge amplification with GEMs in standard gas
Howto: Neutron Detection 6 Cross section: active detection volume Energy of the particles (thin layer) Li α c c c c Energy [MeV]
Howto: Neutron Detection 6 Cross section: active detection volume Energy of the particles (thick layer) Li α c c c c Energy [MeV]
Howto: Neutron Detection 6 Cross section: active detection volume Energy of the particles (thick layer) Li α c c c c Energy [MeV] Deposited energy (in detector gas) Energy [MeV]
Howto: Neutron Detection 6 Cross section: active detection volume
CASCADE an overview 7 CASCADE detector without housing Active Detection Volume - Neutron conversion in Boron-10 10 B + n 7 Li + + 2.79 MeV ( 6%) 7 Li * + + 2.31 MeV (94%) - Charge amplification with GEMs in standard gas Readout - readout stripes: 128 x 128 y @ 1.56mm - double sided
XY Readout 8 Unit Cell: Y stripes 1.56 mm X stripes
CASCADE an overview 9 CASCADE detector without housing Active Detection Volume - Neutron conversion in Boron-10 10 B + n 7 Li + + 2.79 MeV ( 6%) 7 Li * + + 2.31 MeV (94%) - Charge amplification with GEMs in standard gas Readout - readout stripes: 128 x 128 y @ 1.56mm - double sided Electronics -A/D: CiPix Chip (ASIC) with 10 MHz -FPGA based data preprocessing o histogram (on the fly) - Optical GBit Interface
Readout electronics 10 CIPix-Board (X0) Optical Gigabit Link 80 MB/s Optical Gigabit Link N s Detector Frontend CIPix-Board (X1) CIPix-Board (Y0) FPGA based Readout board SRAM (16MB) for monitoring PC CIPix-Board (Y1) DDR-SDRAM (1GB) for histogramming CIPix-Board ( t ) PHA module 5ch, 40MHz, 12bit Specs: 4 CIPix ASICs reading 128x128 channels 1 CIPix ASIC for TOF-resolution down to 100ns FPGA (Virtex 2) based readout, control of CIPix, data-preprocessing and compression electrically decoupled from host computer Next: Replaced by nxyter Next: Replaced by Spartan 6
The CIPIX ASIC 11 CIPix Schematic [1] Timeline FElix chip (RD20, LHC) 1993 HELIX 1.0 HELIX 32 1998 HELIX128-2.2 (HERA-B) HELIX128-3.0 (Zeus) BEETLE (LHCb) CIPix (H1)
The nxyter ASIC 12 nxyter Schematic [1] [1] The n-xyter Reference Manual 1.50, 2009
About: Conduct 2D imaging rate capability efficiency GEM gain Spin Echo
CASCADE Imaging 13 Image of a thermal neutron beam (after guide) Log (Intensity) Cadmium sheet Spatial resolution: 2.4 mm @RESEDA FRM II
Instantaneous Rate [Hz] CASCADE rate capability 14 Count rate > 1 MHz 10 7 10 6 Time of Flight measurements at ILL/ PF1A on a single readout strip of 1cm 2 Maximum inst. rate: 2.7 MHz Maximum detected ever: 4 MHz Limit due to pre-amp pulse width 10 5 classical tubes 10 4 Background due to - neutron gas at ILL/PF1A - and leaking chopper! 10 3 10 2 0 5 10 15 20 25 30 Neutron TOF for 108cm [ms]
Instantaneous Rate [Hz] CASCADE rate capability 14 Count rate > 1 MHz 10 7 10 6 Time of Flight measurements at ILL/ PF1A on a single readout strip of 1cm 2 Maximum inst. rate: 2.7 MHz Maximum detected ever: 4 MHz Limit due to pre-amp pulse width Dynamic range 5 orders of magnitude 10 5 classical tubes 10 4 Background due to - neutron gas at ILL/PF1A - and leaking chopper! 10 3 10 2 Point spread function of 0.57mm beam 0 5 10 15 20 25 30 Neutron TOF for 108cm [ms]
CASCADE detection efficiency 15 20 layers 8 layers 3 layers
CASCADE detection efficiency 16 Efficiencies of the detector at different wavelenghts Simulation Data T-GEM corrected data Measurements at HEIDI, FRM II
CASCADE gain by layer 17 Mean local gas gain v
CASCADE gain by layer 18 Mean local gas gain v
Spin Echo Spectroscopy 19 Application: High resolution neutron scattering: Neutron Resonance Spin Echo Methods Principle: Use Neutron Spin as Obervable in Interference Time Of Flight Experiments e.g. Mach-Zehnder Interferometer in time Spin precision Reverse Spin precision Detector z x Target s x Example: v Schematic: MIEZE I setup Frequency 654kHz, l n = 5Å,v = 800m/s; Spin-Wavelength of signal: 1.2 mm Time dependent scattering at sample causes loss in polarization Polarization is proportional to Fourier Transform of Energy Transfer Spectrum
CASCADE MIEZE 20 Polarization in two pixels: Counts MIEZE frequency 654 khz at 5.4 Å 2 4 6 8 10 12 14 16 ~100ns time bin Signal can be obtained in every single pixel and layer c From: FRM II, Reseda From: FRM II, Reseda
11 CASCADE MIEZE 21 0 P 1 P P 0 1 P δ polarization map Pip δ -p Pi phase front map From: FRM II, Reseda
Summary 22 The CASCADE detector offers an alternative to classical 3 He based systems with spatial resolution (2.6 mm) high count rate capability (up to 2 MHz) high time of flight resolution important for Spin Echo methods Efficiency depends on number of layers: 2x3 layers in operation ( -50% eff. at 5.4 Angstroms) Ongoing Improvements: redesign for better ASIC (CiPix nxyter ) more compact structures & improved field configuration scale up to 10 layers
Backup Slides 10
CASCADE detection efficiency 15 Efficiency and internal scattering
- The Scattering Map Distance [Å] 10 5 10 4 10 3 10 2 10 1 10 0 t NSE [ns] 10-7 10-5 10-3 10-1 10 1 10 3 10 5 10 7 10 9 10 11 Raman Scattering Fabry-Perot Interferometry Photon Correlation Spectroscopy Inelastic Neutron & X-ray Scattering MIEZE Neutron Spin Echo X-ray PC Spectroscopy 10 4 10 2 10 0 10-2 10-4 10-6 10-8 10-10 10-12 10-14 Energy [mev] 10-4 10-3 10-2 10-1 10 0 10 1 q [Å -1 ]
CASCADE MIEZE time bins Neutrons Spatial distance of GEM layers time delay