Measurement of Pulsed Ionizing Radiation at DESY Albrecht Leuschner - - PowerPoint PPT Presentation

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Measurement of Pulsed Ionizing Radiation at DESY Albrecht Leuschner - - PowerPoint PPT Presentation

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28 30 April 2014, SATIF-12, Fermilab Measurement of Pulsed Ionizing Radiation at DESY Albrecht Leuschner , Deutsches Elektronen-Synchrotron DESY, Hamburg Electron Linac FLASH 1.6 GeV 0.8 ms full bunch train 0.2 ps single bunch 10 Hz

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SLIDE 1

Measurement of Pulsed Ionizing Radiation at DESY

Albrecht Leuschner , Deutsches Elektronen-Synchrotron DESY, Hamburg

28 – 30 April 2014, SATIF-12, Fermilab

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SLIDE 2

FLASH

Electron Linac 1.6 GeV 0.8 ms full bunch train 0.2 ps single bunch 10 Hz 100 kW average power

  • 28. April 2014

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SLIDE 3

XFEL

Electron Linac 20 GeV 0.8 ms full bunch train 0.2 ps single bunch 10 Hz 2*300 kW average power

December 2013: Gun: 1st commitioning

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SLIDE 4

Laser-Plasma Acceleration

simulation: Christian Werle laser Simulation of laser-plasma accelerator: The color-coded electron density is shown in the plasma. The laser beam propagates from left to right through the simulation window and generates charge separation. Directly behind the laser pulse a region of reduced electron density is generated (blue), followed by increased electron density (red). Strong longitudinal electric fields up to 1TV/m are built up by the charge

  • separation. They can be used for the acceleration of particle beams.

Projects at DESY: LAOLA and LUX

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SLIDE 5

Parameters of the Plasma Accelerators

Parameter Value Particle Electron Energy up to 2 GeV Charge up to 1 nC Pulse duration 10 fs Repetition rate 5 Hz Beam power 10 Watt Parameter Value Wave length 800 nm Energy 5 Joule Pulse duration 25 fs Repetition rate 5 Hz Beam power 25 Watt

Produced Electron beam Laser

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SLIDE 6

Detector R&D at DESY

  • Radiation monitor system at DESY: PANDORA = Photon

And Neutron Dose Rate meter for Accelerators

  • Cooperation of DESY with the companies

SIS “Struck Innovative Systeme” from Hamburg and “Berthold Technologies” from Bad Wildbad

  • The sensors are available with the trade name LB 6419.
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SLIDE 7

Short Term History

Radiation Bursts Neutrons Photons

In 2002 feasibility study was presented at SLAC for the SATIF-6 ! In 2008 first 26 devices were installed at the PETRA III storage ring.

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SLIDE 8

LB 6419

Plastik - Scintillator

in a 1 cm PE cover 3He - Counter rem – counter type

Electronics- Box

Power supplies FADCRMON board (SIS)

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SLIDE 9

Detector - Concept

Type of Radiation

Low - energy < 20 MeV thermal

Neutrons

High - energy > 20 MeV γ - Radiation

Photons

Bremsstrahlung > 2 MeV Synchrotron Radiation

Continuous Time Structure Burst (sequence)

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SLIDE 10

Terms Pulse  Burst

  • “Pulse” describes the time behavior of the electric signal
  • f a sensor. An exception is: “Pulsed Radiation”.
  • “Burst” describes the time behavior of the radiation

intensity.

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SLIDE 11

Terms Dose –

  • Rate  -Increment
  • The dose increment is the only measured quantity of a radiation burst.

The duration of a burst or even an intensity distribution during the burst are not available for dose measurements (ns, ps ?, fs ???).

  • The dose rate is not suitable for a measured quantity. The dose rate is

meaningful as the average of the dose increments of many bursts in a long time.

  • The user is mislead by dose rates obtained from the accelerator pulse

length, for example 10 nSv / 10 fs = 3.6 Sv/h. → Escape !

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SLIDE 12

Pandora's Action on FLASH

ESRF modus adopted: Act on the LINAC. The experimental hall is a surveyed area. Personal doses are not measured. As the experiments run over a few hours an ambient dose limit of 2 µSv per 4 h (1 mSv per 2000 h ) must be guaranteed. In case of exceeding the dose limit the LINAC operation is blocked until the next 4 hour interval starts.

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SLIDE 13

Action on FLASH

4 h 4 h 4 h 4 h Time Time Dose Dose Beam current Beam current Dose limit 2 µSv Dose limit 2 µSv

Case: „Below limit“ Case: „Above limit“

beam blocked

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SLIDE 14

A FLASH – Logbook Entry

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SLIDE 15

Detector - Concept

Type of Radiation

Low - energy < 20 MeV thermal

Neutrons

High - energy > 20 MeV γ - Radiation

Photons

Bremsstrahlung > 2 MeV Synchrotron Radiation

Continuous Time Structure Burst (sequence)

Scintillator

Pulse height < MIP

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SLIDE 16

Saturation Behavior of a Plastic Scintillator at a Cs-137 source

0,001 0,01 0,1 1 10 100 1000 0,001 0,01 0,1 1 10 100 1000

Response Dose Rate [mSv/h] Reference Dose Rate [mSv/h]

Measured response Linear Response

Extrapolation of the stationary behavior towards short durations

Duration of the Exposure Half-Response- Dose 1 h 50 mSv 1 s 14 µSv 1 ms 14 nSv 1 µs 14 pSv 1 ns 14 fSv 1 ps 14 aSv 1 fs 14 zSv

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SLIDE 17

Half-Response-Dose vs. Burst-Duration

5E-10 5E-09 5E-08 0,0000005 0,000005 0,00005 0,0005 0,005 0,05 0,5 5 50 500 5000 50000 1E-11 1E-10 1E-09 1E-08 0,0000001 0,000001 0,00001 0,0001 0,001 0,01 0,1 1 10 100 1000 1,E-15 1,E-14 1,E-13 1,E-12 1,E-11 1,E-10 1,E-09 1,E-08 1,E-07 1,E-06 1,E-05 1,E-04 1,E-03 1,E-02 1,E-01 Average Dose Rate with 10 Hz [µSv/h] Half Response Dose [nSv] Accelerator Pulse-, Burst Duration [s]

continuous radiation

1 ms 1 ns 1 fs 1 ps 1 µs

measured value natural background

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SLIDE 18

Half-Response-Dose vs. Burst-Duration

5E-10 5E-09 5E-08 0,0000005 0,000005 0,00005 0,0005 0,005 0,05 0,5 5 50 500 5000 50000 1E-11 1E-10 1E-09 1E-08 0,0000001 0,000001 0,00001 0,0001 0,001 0,01 0,1 1 10 100 1000 1,E-15 1,E-14 1,E-13 1,E-12 1,E-11 1,E-10 1,E-09 1,E-08 1,E-07 1,E-06 1,E-05 1,E-04 1,E-03 1,E-02 1,E-01 Average Dose Rate with 10 Hz [µSv/h] Half Response Dose [nSv] Accelerator Pulse-, Burst Duration [s]

continuous radiation

1 ms 1 ns 1 fs 1 ps 1 µs

FLASH full train 1 ms XFEL XFEL

measured value

LAOLA Plasma 10 fs FLASH single bunch 0,2 ps

natural background

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SLIDE 19

Half-Response-Dose vs. Burst-Duration

5E-10 5E-09 5E-08 0,0000005 0,000005 0,00005 0,0005 0,005 0,05 0,5 5 50 500 5000 50000 1E-11 1E-10 1E-09 1E-08 0,0000001 0,000001 0,00001 0,0001 0,001 0,01 0,1 1 10 100 1000 1,E-15 1,E-14 1,E-13 1,E-12 1,E-11 1,E-10 1,E-09 1,E-08 1,E-07 1,E-06 1,E-05 1,E-04 1,E-03 1,E-02 1,E-01 Average Dose Rate with 10 Hz [µSv/h] Half Response Dose [nSv] Accelerator Pulse-, Burst Duration [s]

continuous radiation

1 ms 1 ns 1 fs 1 ps 1 µs

FLASH full train 1 ms XFEL XFEL

measured value

Scintillator Pulse Width 20 ns LAOLA Plasma 10 fs FLASH single bunch 0,2 ps Scintillator Response 1 MeV Scintillator passage @ speed of light

natural background

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SLIDE 20

Half-Response-Dose vs. Burst-Duration

5E-10 5E-09 5E-08 0,0000005 0,000005 0,00005 0,0005 0,005 0,05 0,5 5 50 500 5000 50000 1E-11 1E-10 1E-09 1E-08 0,0000001 0,000001 0,00001 0,0001 0,001 0,01 0,1 1 10 100 1000 1,E-15 1,E-14 1,E-13 1,E-12 1,E-11 1,E-10 1,E-09 1,E-08 1,E-07 1,E-06 1,E-05 1,E-04 1,E-03 1,E-02 1,E-01 Average Dose Rate with 10 Hz [µSv/h] Half Response Dose [nSv] Accelerator Pulse-, Burst Duration [s]

continuous radiation

1 ms 1 ns 1 fs 1 ps 1 µs

FLASH full train 1 ms XFEL XFEL

measured value

Scintillator Pulse Width 20 ns LAOLA Plasma 10 fs FLASH single bunch 0,2 ps Scintillator Response 100 MeV (pile-up) Scintillator Response 1 MeV Scintillator passage @ speed of light

natural background

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SLIDE 21

Half-Response-Dose vs. Burst-Duration

5E-10 5E-09 5E-08 0,0000005 0,000005 0,00005 0,0005 0,005 0,05 0,5 5 50 500 5000 50000 1E-11 1E-10 1E-09 1E-08 0,0000001 0,000001 0,00001 0,0001 0,001 0,01 0,1 1 10 100 1000 1,E-15 1,E-14 1,E-13 1,E-12 1,E-11 1,E-10 1,E-09 1,E-08 1,E-07 1,E-06 1,E-05 1,E-04 1,E-03 1,E-02 1,E-01 Average Dose Rate with 10 Hz [µSv/h] Half Response Dose [nSv] Accelerator Pulse-, Burst Duration [s]

continuous radiation

1 ms 1 ns 1 fs 1 ps 1 µs

FLASH full train 1 ms XFEL XFEL

measured value

Scintillator Pulse Width 20 ns LAOLA Plasma 10 fs FLASH single bunch 0,2 ps Scintillator Response 100 MeV (pile-up) Scintillator Response 1 MeV Scintillator passage @ speed of light

Delta-Burst- Response

Dark Dose

natural background

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SLIDE 22

Half-Response-Dose vs. Burst-Duration

5E-10 5E-09 5E-08 0,0000005 0,000005 0,00005 0,0005 0,005 0,05 0,5 5 50 500 5000 50000 1E-11 1E-10 1E-09 1E-08 0,0000001 0,000001 0,00001 0,0001 0,001 0,01 0,1 1 10 100 1000 1,E-15 1,E-14 1,E-13 1,E-12 1,E-11 1,E-10 1,E-09 1,E-08 1,E-07 1,E-06 1,E-05 1,E-04 1,E-03 1,E-02 1,E-01 Average Dose Rate with 10 Hz [µSv/h] Half Response Dose [nSv] Accelerator Pulse-, Burst Duration [s]

continuous radiation

1 ms 1 ns 1 fs 1 ps 1 µs

FLASH full train 1 ms XFEL XFEL

measured value

Scintillator Pulse Width 20 ns LAOLA Plasma 10 fs FLASH single bunch 0,2 ps Scintillator Response 100 MeV (pile-up) Scintillator Response 1 MeV Scintillator passage @ speed of light

Delta-Burst- Response

Dark Dose

natural background

  • 28. April 2014

Recovery Time after Saturation

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SLIDE 23

Detector – Concept: Separated Responses

Type of Radiation

Low - energy < 20 MeV

Neutrons

High - energy > 20 MeV

Continuous Time Structure Bursts

Scintillator

Pulse height > MIP Recoil Protons

3He Counter

Scintillator: 12C(n,p)12B

3He Counter: 12C(n,x)9Li 3He Counter: TOF

Scintillator: TOF capt. γ

Total response, no pile-up Delayed response only

0,0001 0,001 0,01 0,1 1 10

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20 40 60 80 100 120 140 Counts per burst [1/ms] Time after burst [ms]

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SLIDE 24

Separation of Prompt from Delayed Response

0,01 0,1 1 10 100 1000 10000 0,01 0,1 1 10 100 1000 10000 response burst dose [nSv] reference burst dose [nSv] Pulsed response: delayed B-12 decay Total response: energy deposition from hadrons ReferenceDose 0,0001 0,001 0,01 0,1 1 10

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20 40 60 80 100 120 140 Counts per burst [1/ms] Time after burst [ms]

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SLIDE 25

Definition of Pulsed Radiation

The Half-Response-Dose depends on the burst duration. Delta-Burst-Response * Repetition Rate < Continuous Half-Response-Dose. Time between Bursts (inverse repetition rate) > Recovery time after saturation

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The radiation is regarded as pulsed if

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