Dosimetry at accelerators: state-of-the-art and applications to - PowerPoint PPT Presentation

Dosimetry at accelerators: state-of-the-art and applications to medicine Marco Silari CERN, Geneva, Switzerland University of Milano, 10 th May 2019

Outlook of the presentation • Radiation & Environmental Protection at CERN: past, present and future • The W-MON project • The Medipix/Timepix hybrid pixel detector • MARS CT • The GEMPix and its application in hadrontherapy M. Silari - Dosimetry at accelerators - UNIMI, 10 May 2019 3

Radiation & Environmental Protection at CERN REMUS : CERN R adiation and E nvironment M onitoring U nified S upervision In 2019: 3211 Measurement channels: 864 RP main channels + 1824 auxiliary 523 Environmental channels 26 Types (categories) of monitoring stations 365 days/year, 24/7 operation PS M. Silari - Dosimetry at accelerators - UNIMI, 10 May 2019 4

Radiation & Environmental Protection at CERN Induced Area Radiation Activity Monitoring Monitors ARCON VME Chassis RAMSES Ventilation Monitors Stray Rad Water Monitors Monitors Area Monitoring (ARCON) GRAMS Courtesy Hamza Boukabache, CERN M. Silari - Dosimetry at accelerators - UNIMI, 10 May 2019 5

Radiation & Environmental Protection at CERN Air filled ionization REM counters Gas filled, high pressure chambers ionization chambers Beam-off : to protect workers during Beam-on : to protect workers maintenance and repair against radiation in areas adjacent to accelerator tunnels fields caused by decay of radionuclides and experiments against prompt radiation (mainly gammas, E < 2.7 MeV) (mainly neutrons, E < some GeV) Site Gate Monitors No alarm function Alarm function M. Silari - Dosimetry at accelerators - UNIMI, 10 May 2019 6

CROME ( C ERN R adiati O n M onitoring E lectronics) Alarm Unit Radiation Monitor High Reliability components – Military, Automotive or Industrial qualification Redundant Electronic Embedded Testability Worker Access System / Machines Uninterruptible Power supply supervision Courtesy Hamza Boukabache, CERN M. Silari - Dosimetry at accelerators - UNIMI, 10 May 2019 7

CROME Rackable System Courtesy Hamza Boukabache, CERN M. Silari - Dosimetry at accelerators - UNIMI, 10 May 2019 8

W-MON: remote control of radioactivity in waste containers M. Silari - Dosimetry at accelerators - UNIMI, 10 May 2019 9

Current waste control procedure Origin of the waste containers: • France : Prévessin site, all SPS and LHC site except BA5, BA6, and LHC P1 • Switzerland : Meyrin site, SPS BA5, BA6 and LHC P1 Number of household waste containers controlled: • France :  100 • Switzerland :  150 Meyrin Manual control procedure: • France : once per week, control duration 2 hours • Switzerland : three times per week, control duration 2 hours 2017 report: • 991 measurements campaigns • 104 problems (weather conditions, accessibility, background too high,…) Prévessin • 36 positive controls M. Silari - Dosimetry at accelerators - UNIMI, 10 May 2019 10

The IoT solution Internet Of Things 7 billion devices connected in 2018 15% increase from 2017 10 billions by 2020 source: IoT Analytics Main applications: - Business/manufacturing 40.2% - Health care 30.3% - Retail 8.3% - Security 7.7% - Transportation 4.1% source: Gartner, Inc M. Silari - Dosimetry at accelerators - UNIMI, 10 May 2019 11

The W-MON project Distributed network of radiation sensors to monitor radioactivity in waste Server User apps Gateway / Concentrator REMUS End-devices Database CERN M. Silari - Dosimetry at accelerators - UNIMI, 10 May 2019 12

Requirements for an automated system 1. Gamma rays radiation detection 2. Sensitivity down to background level 3. Robust device, resistant to adverse weather conditions, temperature variations, mechanical shocks 4. Low power consumption (battery powered)  minimum maintenance 5. Wireless data transmission 6. Real-time information 7. Relevant information: alarm for radiation level above threshold, alarm for equipment malfunctioning, GPS information, data logging M. Silari - Dosimetry at accelerators - UNIMI, 10 May 2019 13

The W-MON project • 2014 : Identification of the sensor technology Proof of principle  D-shuttle optimal solution as radiation sensor • 2015 : CERN collaboration agreement with Chiyoda and AIST Feasibility studies  Determination of the number and position of the sensors in the container 2016 : Data handling and communication  The beginning of LoRaWAN at CERN • Collaboration with IT for the deployment of a distributed network of LoRa gateways at CERN • 2017 : Reliability tests Development of a wireless version of the D-shuttle Development of a custom server and data base before integration into REMUS • 2018 : Migration to CERN LoRa network Design of the final customized wireless radiation solution (sensor + communication boards) Optimisation of power consumption M. Silari - Dosimetry at accelerators - UNIMI, 10 May 2019 14

Current approach: D-shuttle D-shuttle personal dosimeter Reader Reader + PC interface • Hamamatsu Si PIN diode • Communication board with optical and 2.4 GHz RF transmitters • Shock sensor • Lithium battery, lifetime 1 year (2 readings per day) • Dose reading from 0.1 µSv to 100 mSv • Size 68 mm x 32 mm x 14 mm and 23 g weight M. Silari - Dosimetry at accelerators - UNIMI, 10 May 2019 15

LoRaWAN: Long Range Wide Area Network Network server Gateway Devices LoRaWAN protocol LoRA 4G/3G/WiFi 4G/3G/WiFi Up to 15 km range Ethernet Ethernet Low bit rate -> Low consumption / Frequency band 868 MHz (EU), (920-925 MHz Japan) M. Silari - Dosimetry at accelerators - UNIMI, 10 May 2019 16

Test in operational conditions (April – November 2017) Lid Middle Bottom Industrial radiography in a nearby building M. Silari - Dosimetry at accelerators - UNIMI, 10 May 2019 17

LoRa @ CERN nTOF ISR Kindergarten PS Points received Gateway position • Five devices registered and sending data to the CERN LoRa network • LoRa range tests and antenna deployment in collaboration with CERN-IT group • Full coverage of all CERN sites by 2019 M. Silari - Dosimetry at accelerators - UNIMI, 10 May 2019 18

The low power consumption requirement Low power optimization is one of the main challenges. The devices shall be: • Portable, small and compact • Battery powered LTC battery with nominal • Battery lifetime of several years capacity of 2.5 Ah From the standard D-shuttle with optical data extraction to the new long range wireless D-shuttle with SPI Integrated Current (mA) Current (mA) current 0.12 mAh  0.023 mAh with SPI Optical Data transfer 60 65 70 75 80 85 90 60 65 70 75 80 85 90 Time (s) Time (s) New transmission time with SPI = 175 ms !! M. Silari - Dosimetry at accelerators - UNIMI, 10 May 2019 19

Possible W-MON architectures Master - slaves All masters WiFi master master 1) Each master extracts its own data from the 1) The master waits for the data from the dosimeter slaves. Data is sent via WiFi 2) Each master sends its own data to the 2) Master sends all data through LoRa to the server via LoRa server M. Silari - Dosimetry at accelerators - UNIMI, 10 May 2019 20

Exploring other options • Another candidate – BG51 gamma radiation sensor from Teviso • Ultra low power requirement (25 µA) • Detector sensitivity: 5 cpm/µSv/h • High immunity to RF and electrostatic fields • Measurement range of dose rate 0.1 µSv/h to 100 mSv/h • Pulse count rate: 5 cpm ± 15% for 1 µSv/h radiation dose rate M. Silari - Dosimetry at accelerators - UNIMI, 10 May 2019 21

Medipix/Timepix and some medical applications M. Silari - Dosimetry at accelerators - UNIMI, 10 May 2019 22

Hybrid pixel detectors • Hybrid pixel detectors are used in high energy physics (HEP) experiments because they provide practically noise- free ‘images’ of particle collisions taken with the equivalent of a very high speed shutter • A preamplifier amplifies the charge deposited by a passing particle in a sensor producing a fast shaped pulse • This pulse is compared with a threshold • Given the very small capacitance at the input of the pixel electronics, the front-end provides a response with an equivalent input noise charge of 100 e − rms even at shaping times of 25 ns. If a threshold is set at 1000 e − the binary information contains practically no noise M. Silari - Dosimetry at accelerators - UNIMI, 10 May 2019 23

Hybrid pixel detectors • In the hybrid pixel detector architecture the radiation sensor element and the readout are processed separately • The sensor is segmented with the same geometry as the readout chip and detector and readout cells are connected using standard flip-chip technology • The separation in processing allows for independent optimization of readout and sensor and different sensor materials can be used with the same readout. Schematic of a hybrid pixel detector with the sensor chip and the electronics chip connected via bump bonds M. Silari - Dosimetry at accelerators - UNIMI, 10 May 2019 24

Medipix2/Timepix assemblies Single assembly Pixels: 256 x 256 Pixel size: 55 x 55 m m 2 Area: 1.5 x 1.5 cm 2 Quad assembly Pixels: 512 x 512 Pixel size: 55 x 55 m m 2 Area: 3 x 3 cm 2 M. Silari - Dosimetry at accelerators - UNIMI, 10 May 2019 25