Design, construction and test of Boron Array Neutron Detector - Gas Electron Multiplier (BAND-GEM)

Transcription

1 Design, construction and test of Boron Array Neutron Detector - Gas Electron Multiplier (BAND-GEM) Radiation portal monitors for screening people, vehicles, and cargo. Measuring neutrons streaming from enriched uranium and weapons-grade plutonium. Detector networks for continuous monitoring of radiation in cities. Challenge of replacing 3 He in proportional counters.

2 10 Boron-based Thin Film Gaseous Detectors Efficiency limited at ~5% (2.5Å) for a single layer nat B contains 80 at.% 11 B and 20 at.% 10 B gas volume 10 B 4 C layer 4 He 4 He neutron 7 Li 7 Li Boron is difficult to deposit Use 10 B 4 C Conductive, stable

3 Enhancing the efficiency of 10 B-based Neutron Detectors 10 B 4 C layer substrate 1 MulS layer gas volume neutron Generic approaches to improve efficiency 2 Grazing angle (<10 ) gas volume 10 B 4 C layer substrate 10 B 4 C layer neutron

4 Efficiency of 10 B Detectors: Perpendicular Geometry Single layer is only ca.5% CalculaSons done by many groups AnalyScal calculasons extensively verified with prototypes and data 10 B 4 C layer! substrate gas volume Details mater: just like for 3 He!neutrons MulSlayer configurason (example):!!!!!!!!!!!!!!!!!!!!!!!!!mul%&grid!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! 3 He!tubes!!1!inch!!4.75!bar!!! JINST 8 (2013) P04020 efficiency diameter! Dead!space!considered! wavelength(å)

5 Efficiency of 10 Boron Detectors: Inclined Configuration part=1.3&filename=b26e880b-6b77-44e2-b4d d0cb6d.jpg gas volume gas volume!neutron θ 4 He 4 He 7 Li 10 B 4 C layer 7 Li 4 He 7 Li A 10A efficiency θ (deg) F. Piscitelli, PhD Thesis, U.Perugia (2014)

6 Micropattern Gaseous Detectors Field started by A Oed at the ILL with the micro-strip gas chamber (MSGC) in 1988 Now widespread: many variants Potentially very good resolution and very high rate capability eg Gas Electron Multiplier (GEMs) Rate tests with thermal neutrons Growing interest for applications for neutron detection 2 workshops organised by CERN RD51 Collaboration (with HEPTECH) on Neutron Detection using MPGDs Summary of 1st workshop for MPGDs for neutron detection: arxiv: nd Workshop: arxiv:

7 First prototype: bgem Single layer B4C 1 µm thick B4C coated aluminium plate cathode on top of Triple GEM structure B 4 C coated aluminium cathode B 4 C coated aluminium cathode assembled inside the bgem chamber layout Padded readout anode pad area = 8x8 mm 2

8 BAND-GEM GEM

9 BAND-GEM Principle and prototype 2 mm 6 cm

10 New Front End Electronics The BAND-GEM prototype electronics is based on CARIOCA Chip. Total dimension : 3x6 cm 2 Digital Chip with 8 channels Equips the LHCb GEM detectors Fast chip used for triggering Adapted from MWPC A new chip is being tested: the GEMINI chip. Mixed analog and digital chip that Has 16 channels/chip. Especially developed for GEM detectors

11 Next: Small Area Demonstrator In order to test the technology processes suitable for large area detectors and to validate the numerical simulations as soon as possible, the project will produce a small scale prototype (active volume=5x10x10 cm 3 ).

12 Projected performance: from Prototype to Demonstrator Prototype - Achieved Demonstrator - Projected Lamella Distance 2 mm 4 mm B 4 C/empty rauo on lamellas 1 3 Full Lamella System length 6 cm 10 cm Lamella Thickness 250 µm 200 µm Lamella Material Aluminium Oxide Aluminium OpUmal Ult angle 7 degrees 5 degrees Pulse Height Threshold 70 kev 120 kev Cathode area 5x10 cm 2 5x10 cm 2 Count Rate Capability 10 MHz/cm 2 12 MHz/cm 2 Gamma Ray SensiUvity 5* Measured 1.5 Å 18.5% // Expected 1.8 Å 21.2% 33% Expected 4 Å 49% 64% Front-end ASIC CARIOCA 8 channels/chip GEMINI 16 channels/chip

13 To be addressed under NMP Small area BAND-GEM demonstrator - with optimized performance - using technology scalable to large areas Simulation -> Design -> Construction -> Test -> Analysis -> Projections Main features: - converter geometry optimized for improved charge collection - robust materials - new readout chip - attention to cost/m 2