munich-centre for advanced photonics a pixel detector system for laser-accelerated ion detection...

Munich-Centre for Advanced Photonics

A pixel detector system for laser-accelerated ion detection

Sabine Reinhardt

Fakultät für Physik, Ludwig-Maximilians-Universität München, Germany

Instrumentation for Diagnostics and Control of Laser-Accelerated Proton (Ion) Beams: 2nd Workshop, Paris, France07.-08.06.2012


Detection of laser-accelerated proton (ion) beams:

• Ultra-short (<= ns) highly intense (> 107 ions/cm2) ion pulses

• EMP presence

• Mixed radiation background

• Large energy spread of ions

g Challenge for any electronic online detector



108 particles / cm²

=

1 particle / µm²

A, N constA

NΦ 1/4 A g 1/4 N

Pixel detector as online detector in Thomson spectrometer:

• real time measurement

• excellent spatial resolution

• good energy resolution

Investigated detector systems:

• Kappa DX-4 (commercial system)

• Timepix (scientific system)

collaboration with IAEP CTU Prague

• RadEye (commercial system)



Munich 14 MV Tandem accelerator

• Electrostatic accelerator

• protons: 8- 25 MeV

• 3 irradiation modes:

single particle

continuous

pulsed

107 protons /cm2/ ns

g similar to laser ion pulse

Unique possibilities to test detector response



Kappa DX-4

• Kodak CCD sensor KAI 1020

• 7.4 mm x 7.4 mm pixel size

• 2 mm depletion depth

• commercial system

• integrating detector



Summary

+ Dynamic range:

1 - 106 p/cm2/pulse

+ Linear response

+ Radiation hardness

(20 MeV, 107p/cm2):

1000 shots

- Charge sharing effects

- Small sensitive area

No choice for detector system



Timepix (in collaboration with IAEP CTU Prague)

• Medipix collaboration (CERN)

• hybrid detector system

• 300 mm Si-sensor

• 256 x 256 pixel (50 x 50 mm2)

• 3 different read-out modes:

• Medipix mode (counting)

• Timepix mode (time)

• TOT mode (energy)

Single event

Double event

cluster = adjacent pixel above threshold



No choice for detector system

+ Single particle response

+ Linear response

+ Good energy resolution

65 keV @ 5239 keV

- Large charge sharing effects

- Small sensitive area

- - Saturation and non-linear effects

2.5 . 105 p/cm2 /pulse

Summary



Rad Eye detector system

• RadEye 1 sensor

• Si-photodiode array

• 48 mm x 48 mm pixel size

• 2 mm depletion depth

• large sensitive area:

25 mm x 50 mm

• commercial system

• integrating detector




• continuous beam

• 15 MeV protons

• ~ 104p/cm2/s

No charge sharing effects observed

Single and double hits can be distinguished

Cluster distribution:

Cluster pixel distribution:

single hit double hit

Single proton sensitivity




• pulsed beam

• 20 MeV protons

• 104 - 107 p/cm2/ns

c d

a b

Good agreement to continuous measurements

No saturation observed




• continuous + pulsed beam

• 20 MeV protons

• <= 6 .1010 p/cm2

Lifetime n 90% residual dynamic range

3000 shots

(20 MeV, 107p/cm2)

Radiation hardness

System ready for laser-ion-acceleration experiment !



MPQ Atlas laser

• 2.5 J, 30 fs,

• focal spot 3 mm (FWHM)

• 5-10 nm DLC foils

• wide angle spectrometer

dipole set 2 x 0.5 T

entrance slit 0.3 x 140 mm2

• Eproton > 1 MeV

RadEye-System

DLC foil Entrance slit

dipole set Al- foillaser



Pixel value spectrum:

Peak position n Energy loss

Peak content n Average number of proton hits per pixel



Sensor “C” Sensor “D”

g Good agreement with Tandem calibration



SRIM 2008:

Energy loss simulation

Energy conversion:

1.11 +/- 0.09 ADU/keV

Test with with a-source:

g good agreement



MPQ Atlas laser

• 400 mJ, 30 fs

• 20-40 nm DLC foils

• small angle spectrometer

only dipole 0.5 T

pinhole 2.5 mm

• Eproton > 4 MeV



Compact integrated system “RE4PC”

Stand alone system

computer control and read-out

electronics

Compact size: 30 x 25 x 25 cm3

Parallel read-out of 4 RadEye detectors



Astra Gemini laser

• 4-6 J, 50 fs

• focal spot: 3 mm (FWHM)

• target: 75 nm plastic foil

• p > 3.7 MeV

• C > 20 MeV

p

??

6+C



Conclusion

RadEye-Detector Single proton sensitivity Limited energy resolution Sufficient radiation hardness Linear pulse dose response up to 107 p/cm2

No problems with EMP in laser-environment

RE4PC Compact pixel detector system based on RadEye sensor developed Sensitive area as large as 100 x 50 mm2

Extension of functionality planned (trigger, read-out speed, ...)

RE4PC in routine use for laser accelerated proton and carbon ion detection



Many thanks to

Wolfgang Draxinger, and Walter Assmann

Klaus Allinger, Jianhui Bin, Wenjun Ma and Jörg Schreiber

Carlos Granja and Frantisek Krejci

Thanks for your attention!

munich-centre for advanced photonics a pixel detector system for laser-accelerated ion detection...

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