GEMs and Solid State Converters

Transcription

1 Neutron Detection with CASCADE The synthesis of GEMs and Solid State Converters

2 Contents Conduct Construct

3 The Helium-3 crisis 2 9/11 Costs: /L If you can get it Size of the Helium-3 Stockpile, [1] [1] AAAS, Overview of Helium-3 Supply and Demand

4 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)

5 About: Construct

6 CASCADE an overview 4 CASCADE detector without housing 200mm x 200mm

7 CASCADE an overview 4 CASCADE detector without housing Active Detection Volume Readout Electronics

8 CASCADE an overview 5 CASCADE detector without housing Active Detection Volume - Neutron conversion in Boron B + n 7 Li MeV ( 6%) 7 Li * MeV (94%) - Charge amplification with GEMs in standard gas

9 Howto: Neutron Detection 6 Cross section: active detection volume Energy of the particles (thin layer) Li α c c c c Energy [MeV]

10 Howto: Neutron Detection 6 Cross section: active detection volume Energy of the particles (thick layer) Li α c c c c Energy [MeV]

11 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]

12 Howto: Neutron Detection 6 Cross section: active detection volume

13 CASCADE an overview 7 CASCADE detector without housing Active Detection Volume - Neutron conversion in Boron B + n 7 Li MeV ( 6%) 7 Li * MeV (94%) - Charge amplification with GEMs in standard gas Readout - readout stripes: 128 x mm - double sided

14 XY Readout 8 Unit Cell: Y stripes 1.56 mm X stripes

15 CASCADE an overview 9 CASCADE detector without housing Active Detection Volume - Neutron conversion in Boron B + n 7 Li MeV ( 6%) 7 Li * MeV (94%) - Charge amplification with GEMs in standard gas Readout - readout stripes: 128 x mm - double sided Electronics -A/D: CiPix Chip (ASIC) with 10 MHz -FPGA based data preprocessing o histogram (on the fly) - Optical GBit Interface

16 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

17 The CIPIX ASIC 11 CIPix Schematic [1] Timeline FElix chip (RD20, LHC) 1993 HELIX 1.0 HELIX HELIX (HERA-B) HELIX (Zeus) BEETLE (LHCb) CIPix (H1)

18 The nxyter ASIC 12 nxyter Schematic [1] [1] The n-xyter Reference Manual 1.50, 2009

19 About: Conduct 2D imaging rate capability efficiency GEM gain Spin Echo

20 CASCADE Imaging 13 Image of a thermal neutron beam (after guide) Log (Intensity) Cadmium sheet Spatial resolution: 2.4 FRM II

21 Instantaneous Rate [Hz] CASCADE rate capability 14 Count rate > 1 MHz 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! Neutron TOF for 108cm [ms]

22 Instantaneous Rate [Hz] CASCADE rate capability 14 Count rate > 1 MHz 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! Point spread function of 0.57mm beam Neutron TOF for 108cm [ms]

23 CASCADE detection efficiency layers 8 layers 3 layers

24 CASCADE detection efficiency 16 Efficiencies of the detector at different wavelenghts Simulation Data T-GEM corrected data Measurements at HEIDI, FRM II

25 CASCADE gain by layer 17 Mean local gas gain v

26 CASCADE gain by layer 18 Mean local gas gain v

27 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

28 CASCADE MIEZE 20 Polarization in two pixels: Counts MIEZE frequency 654 khz at 5.4 Å ~100ns time bin Signal can be obtained in every single pixel and layer c From: FRM II, Reseda From: FRM II, Reseda

29 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

30 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

31 Backup Slides 10

32 CASCADE detection efficiency 15 Efficiency and internal scattering

33 - The Scattering Map Distance [Å] t NSE [ns] Raman Scattering Fabry-Perot Interferometry Photon Correlation Spectroscopy Inelastic Neutron & X-ray Scattering MIEZE Neutron Spin Echo X-ray PC Spectroscopy Energy [mev] q [Å -1 ]

34 CASCADE MIEZE time bins Neutrons Spatial distance of GEM layers time delay