Accelerator of your ambitions

Arnaud Chapon (

Subsidiary of:
In collaboration with:

  • History
  • Context
  • Accelerator project
  • Implementation
  • Irradiation of materials
  • Examples of applications

For our entities, the prevention concept is the implication for the reliability of the installations, the health-safety and the environmental protection



Calibration of Radiation Survey Meters:

  • According to French law (decree of May 21st, 2010), periodicity of the calibration is three-year.

  • It consists in measuring the instrument characteristics supplied by its calibration certificate (established by the manufacturer before the first commissioning).

Method of calibration of radiation survey meters usually implemented:

  • uses an irradiator containing several radioactive sources,

  • consists in verifying that the measured value of the instrument coincides with the expected dose rate of the source at a given distance and activity.
Example of an irradiator (CEA)
  • Cost of the sources and renewal:
    • three radioactive sources (137Cs),
    • to renew every 10 years.

  • Low productivity:
    • one radiation survey meter at a time,
    • necessity to move the radiation survey meters to cover the dose rate ranges.

  • Narrow energy range:
    • a single energy (662 keV).

Accelerator project

Objectives of CERAP:

  • Develop a new calibration method of ionizing radiations measuring instruments on wide ranges of energies and dose rates,
  • Get rid of radioactive sources.

Envisaged way:

  • Use the braking rays of electrons accelerated at few MeV as the source of calibration.

Singletron 3.5 MeV HVE:

  • Accelerated electrons up to 3.5 MeV,

  • Conversion target
    ⇒ braking rays,

  • Variation of the beam current to cover the various dose rates,

  • Instruments at fixed positions.


  • Wide range of energy,
  • Dose rate ∝ beam intensity,
  • No radioactive source,
  • Possibility of automation.


  • Definition of irradiation sequences ⇒ reduction of the risk of error,
  • Saving time ⇒ reduction of the immobilisation time of the material.
Bayeux/Geant4 modelisations Experimental datas – IBA

New location:

  • ∼700 m2 building,
  • Irradiation room / Accelerator room,
  • Maintenance workshop, reception/storage/expedition area,
  • Liquid Scintillation Counting laboratory,
  • Offices, meeting room.



  • Wide range of energy,
  • Dose rate ∝ beam intensity,
  • No radioactive source,
  • Possibility of automation.


  • Control of the accelerator:
    • accuracy and stability,
    • homogeneity.
  • Process fiabilisation:
    • reproductibility,
    • automation.
  • Traceability of the reference fields:
    • connecting, in terms of dose equivalent rate, to the national reference.

Development of a monitoring ionization chamber

  • Objective: regulate the accelerator current at low dose rates

  • Specifications:

    • specific measure at low levels of irradiation
      from 1 µSv/h to 15 mSv/h at 3 meters of the target
    • resistance to strong irradiations
      > 500 Gy/h
    • quick response time
      of the order of one second

Uniformisation of the irradiation field

Definition of a scanning function on the target

  • Dimensions of the target: 40x220 mm2
  • Vertical scanning: 1 kHz
  • Horizontal scanning: 25 Hz

Homogeneity of the irradiation field: up to 99,8% on +/-15°

Reproductibility of the instruments positioning

Design of an adapted samples carousel:

  • Rotating device,
  • Custom-made templates for every types of instruments,
  • Fixed Camera where the instruments are put,
  • Reference ionization chambers placed in the field.
Dolphy Minitrace
6150AD FH-40

Fiabilisation of the calibration process

  • Objective: automation of the irradiation sequences and establishment of calibration reports to reduce the risk of error

Automation of irradiation sequences:

  • Fixed energy of the incidental beam
    ⇒ Radiation field fitted to the response of every instrument,

  • Adjustment of the beam to various current levels
    ⇒ Control of the full range of every instrument,

  • Statement of the environmental data:
    • reference equivalent dose rate,
    • indication of the instrument,
    • pressure, temperature, hygrometry,

  • Rotation of the carousel.

KERMA in air, Kair, cinetic energy transfered to the charged particules (Gy or J/kg): Kair=KC+KR
KC: At the electronical balance (compensation of the energy of charged particules entering and leaving the volume), KC=D; KR: Contribution of the braking rays

Measurement of the KERMA in air and associated uncertainty:

  • Transfert chamber developed by the CEA-LIST/LNHB

Conversion from Kair to H:

  • Spectrometric measurement of the irradiation fields,
  • Determination of the conversion coefficients hK such as H=hK.Kair

Calibration of radiation survey meters:

Comparison of the indication of the instrument
to the indication of the calibrated chamber

Reports edition:

QR codes associated with the status of the instruments
Example of metrology label
Example of report

Irradiation of materials

FELIX accelerator

  • Electrostatic accelerator:
    continuous beam
  • Dimensions of the irradiation room:
    3 x 6 m2
  • Removable X target:
    possible irradiation in X or in e-
  • Beam scanning:
    uniform field +/- 15°
  • Energy range:
    0.2 - 3.5 MeV
  • Current:
    ~1 pA - 1 mA
  • Dose rate in X at 1 m:
    0.1 µGy/h - 500 Gy/h
  • Dose rate max:
    up to 10 kGy/s in e-


Removable X target:

Possible irradiation in X or in e-

Irradiation chamber allowing to simulate extreme environmental conditions:

  • Temperature tuning:
    • from 80 K to 600 K,
  • Atmosphere tuning:
    • Irradiation in vacuum,
    • Irradiation under N2, Ar, Air, etc.
  • Samples size until 150x150 mm2.
Development of detectors
Calibration with a calibration source
Ageing tests
Semiconductor doping
Fault measurement
Qualification of components for aerospace
Cross-linking, polymer grafting
Thin film surface treatment
Fireproofing of cables and tubes
Professional training
Drafting of certification application files
Sterilisation of medical equipment
Research in radiobiology
Phytosanitary water treatment
Improvement of food preservation

Help to the understanding of the physico-chemical processes:

  • Partnerships with research laboratories

  • Dedicated modelisation tools

Examples of applications

Electric performances of HEMTs GaN* components:*:

  • Military applications, nuclear industry, spatial
  • High-power, high-frequency
  • Excellent thermal stability
  • High tolerance to radiations

Improvement of the performances of HEMTs after irradiation:

  • Electrical Performances
  • RF Performances

Irradiations e- and X in stable beam, low dose rates

* Gallium-nitride based High Electron Mobility Transistors

Selection of valve bodies for the ITER project:

  • Polymer membran
  • Expansion at temperatures >300°C
  • Same behavior under irradiation
    ⇒ Low sensitivity to cross-linking

Selection of equipment the most resistant to irradiation:
Definition of a preventive maintenance plan

Irradiations X in controlled temperature and atmosphere
Complementary studies

Microstructural evolution of steels under irradiation:

  • Models of current PWR and gen IV reactor vessels

Faults creation (Frenkel pairs), at the origin of the ageing under irradiation of materials, in a simple and controlled way.

Irradiations e-, 2 MeV, 1 mA at 300°C (LAETICIA),
to 0.1 dpa (dose received by a REP tank in 40 years).

Measure of electrical charge radius of the proton:

  • Spectroscopy (hydrogene or muonium)
  • Diffusion (electron/proton or muon/proton)
  • Incompatibility until 7σ

Constant R of Rydberg, radiative corrections?

New measurements in diffusion e-/p

  • Sensibility to the transferred quadri-moment Q2
  • The low already obtained: 10-4 GeV2
  • Accessible to ATRON: 10-7 GeV2

Irradiation e- to 3.5 MeV of a solid H target with a diameter of 15μm
precision to 10-4 in energy, luminosity and angular divergence

Accelerator of your ambitions