Laser-assisted gamma sources for industrial application

RA4 team, presented by Nikolay Djourelov PhD, Senior ResearcherPositron Group

Outline

• Laser to Gamma Beam (Gamma Beam System)

• Positron source from gamma beam:

• Slow positron beam and spectrometers

• Nondestructive studies with positrons

• Gamma beams nondestructive material inspections:

• Nuclear resonance fluorescence

• Gamma ray attenuation

Extreme Light Infrastructure-Nuclear Physics

(ELI-NP) - Phase II

(γ,α) and (γ,p) reactions

Nuclear Photonics

Photofission

(γ,n) and (γ,γ’) reactions

• Nuclear Resonance Fluorescence (, )

• Nuclear Astrophysics (,p) (,)

• Photonuclear Reactions (,n)

• Photofission & Studies of Exotic Nuclei

Gamma Beam System (EuroGammaS) Narrow bandwidth (≤0.3%) gamma-beams up to 19.5 MeV

~ 4γ2·EL

L

Lee

Le E

mc

Ea

E

220

2

2

41

cos12

Positron Source, Beam Transport & Positron Laboratory Instruments

Moderation to obtain slow e+

• Thin films

• Layered structures

• Buried layers

• Depth profiling

e+

107 e+/s

Positron Spectroscopy Applications for Material Science

PALS (e+ lifetime)

Large positronlifetimedatabase

Basic studies by PALS

• Defect size (type)

• Free volume hole size

• Pore size

• Relative concentration !

• Micro & Meso pores

but not Macro pores

• Open & Closed porosity

CDBS (e- momentum)

or RF clock

C.Hugenschmidt et al., Phys. Rev. B 77, 092105

Gamma beam nondestructive material inspections

Active interrogation –Nuclear resonance fluorescence

Gamma imaging –Radiography and tomography

Aim: Use the gamma beam as a probe to study the structural properties and the elemental composition of industrial objects

Nuclear resonance fluorescence

ELI-NP Array of Detectors

NRF + CT Elemental/isotopic maps

ELIADE

Transmission and scattering NRF setup

Distinguish 238U from 235U by tuningthe gamma beam energy to the NRFtransition energy of 238U (Eγ = 2.176MeV) and using 5 mm of 238U for awitness foil (21 h at ELI-NP).

238U

235U

Transmission NRF NRF/Transmission

NRF used in combination with radiography and tomography at ELI-NP can produce isotope-specific maps at single resonance level

Object

ELI-NP

γ beam

Transmission

detector

Witness foil -238U

ELI-NP beam

Δ E/E = 0.5 %

2.176 MeV

ε= 8 x 0.5 %

3x108 ph/s

Transmission NRF setup

Scattering NRF setup

Energy (a.u)20- 0 20 40 60 80 100

50-

0

50

100

150

200

250

[0]/sqrt(2.0*TMath::Pi())/[2]*exp(-(x-[1])*(x-[1])/2./[2]/[2])-50

Co

un

ts

Co

un

ts

Energy (a.u)

decrease is due to resonant absorption

0 20 40 60 80 100

0

500

1000

1500

2000

[0]/sqrt(2.0*TMath::Pi())/[2]*exp(-(x-[1])*(x-[1])/2./[2]/[2])-10

DE/E ~ 0.5%

LCS beam w/o absorberLCS beam w absorber

resonant absorption (Eγ, ~ meV)

Industrial radiography and tomography at ELI-NP

• Performance estimated based on analytical model and GEANT4 simulations

• Cone-beam and fan-beam CT simulations: • 0.2 mm to 1 mm holes and spacing• Fan beam: 2.5 x 107 ph/s, 1 mrad, 1 MeV• 1 projections/s

Nr ofprojections

Resolutionlimit

33 0.6 mm

66 0.4 mm

100 0.2 mm

Image large and/or complex objects with high resolution: 2D and 3D imaging

Energy (MeV) 2 3.5 9.87 19.5

Source divergence (μrad) 140 100 50 40

Nr of photons within the

FWHM bandwidth 4.0x108 3.7x108 8.3x108 8.1x108

Al(cm) 30 41.2 88.9 104.9

Fe (cm) 10.4 13.5 23.7 24.3

H2O 70.8 100.5 250.1 337.1

Concrete (cm) 33.8 47 106.8 131.6

Rates/macrobunch 1.9x103 2.9x103 3.9x103 3.4x103 *Stainless steel (SS) grid: a = 0.7 mm; f=0.5; RC = 0.7 mm, i.e the beam spot at the sample is as large as a.

Example: Distinguish a 0.7 mm SS wire in an object of 40 cm Al in a 1s exposure

Interactionpoint

Detector

2θ

Main collimator

ELI-NP Team, March 5, 2013

Thank you!

8