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Aug 19, 2023 475 likes •658 views

Characterization of photo-neutrons produced by laser- plasma accelerated electrons impinging on high Z-metallic targets for developing high brightness and pulsed neutron source El-Tayeb El-Saady & Mostafa M. Alashmawy Nuclear and

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Characterization of photo-neutrons produced by laser- plasma accelerated electrons impinging on high Z-metallic targets for developing high brightness and pulsed neutron source

El-Tayeb El-Saady & Mostafa M. Alashmawy Nuclear and Radiological Regulatory Authority

N. Hafz

Key Laboratory for Laser Plasmas, Shanghai Jiao Tong University, China

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Ob Objecti ectives ves

♦ Generation of 1.2 GeV and 150 MeV electrons by laser Wakefield acceleration (LWFA). ♦ Electron charge measurements ♦ Plasma density measurements by plasma interferometer. ♦ Generation of pulsed neutrons from 1.2 GeV and 150 MeV electrons by photo-nuclear reaction. ♦ MCNP calculations of Neutron yield, Angular distribution, Energy spectrum and Nuclear Temperature

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Fission reaction
Conventional Accelerators
Radioactive sources
Fusion reactions
Laser plasma accelerators

Neutro tron So Sources rces

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Las aser r wak ake fi field ac acceler elerat ation

n (LWFA

FA)

ultra-intense laser used to excite plasma wave (wake fields)

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a tabletop 200 TW, 10Hz, Ti: Sapphire 30 fs laser
4-mm-long supersonic nozzle gas-jet target N&He
Integrating current transformer (ICT) for electron

Charge measurement

Fluorescent screen and a 14-bit CCD camera for

imaging the spatial profile of the accelerated electron beams Sh Shan angha hai i Jia iao

Ton
ng Las

aser r fa facil ilit ity

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laser er plasm sma a experim iment ent at KEY laborato atory, y, Shang anghahi ahi Jiao Tong g Uni.

EXP.1 1.2 GeV electron is produced from under dense plasma Charge 10pC/p the plasma density (ne) 3.35×1018 cm -3 (Mach-Zehnder interferometer) Pulse duration 30 fs Pulse repetition 10Hz Energy spread 5%

EXP. 2

150 MeV electron is produced from dense plasma the plasma density (ne) 4.0×1019 cm -3 Charge 22pC/p Pulse duration 30fs Energy spread 1%

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0.4 0.8 1.2 1.6 8 16 Charge Density

Electron Energy (GeV)

7.1%

FWHM

A C

Divergence (mrad)  (10-4 pC/MeV)

15 15 Electron Energy (GeV) 0.53 0.2 0.8 0.3 1.15

(A) Simulation result using OSIRIS code showing the evolution of the laser pulse electric field (red) and the wake wave’s pseudo-potential difference (black). (B) False-color ICCD image of 1.2 GeV electron beam

n the florescent screen after a calibrated magnet spectrometer. This electron beam was generated by

focusing 120 TW laser pulse on a 1.8 ×1018 cm-3 plasma of helium gas mixed with low traces of nitrogen

gas. (c) The deconvoluted energy spectrum of the image in (B).

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MCNP Code de Validation

♦ Monte Carlo MCNP calculations depend sensitively on the simulation geometry ♦ To check the photonuclear physics contained in the code ♦Cylindrical lead target (Pb-207) (thickness 1.68 cm and radius 3 cm), for which measured data are available (IAEA TR-188, 1979) ♦ Show good agreement with the published data

1.E+09 1.E+10 1.E+11 1.E+12 1.E+13 5 10 15 20 25 30 35 40 45 Incident Electron Energy (MeV) Photoneutron Yield (N S-1 kW-1) MCNP IAEA 188 Petwal V. C. et al

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Neutron Yield

0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 20 40 60 80 100 120 140 160 Thickness (g/cm

Neutron Yield (neutrons/e -) W Ta Pb 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 20 40 60 80 100 120 140 160 Thickness (g/cm

Neutron Yield (neutrons/e -) 1GeV 150 MeV

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Max. Yields

Target Electron beam energy

Max. Yield

(neutrons/e-) Optimized thicknes s (g/cm2) Optimized thickness (cm)

Tungsten Z=74, D=19.24 1GeV 3.47.10-1 140 7.28 150MeV 5.23 .10-2 100 5.2 Tantalum Z=73, D=16.4 1GeV 3.2 .10-1 140 8.5 Lead Z=82, D=11.34 1GeV 2.98 .10-1 140 12.35

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Accelerator Type Electron beam energy electron-neutron conversion factor (photons/e-) electron fluence (electrons/s)

Max. Neutrons

Yield (neutrons/s) laser plasma Acc. 1GeV 3.47.10-1 0.624. 10 9 2.2 . 10 8 150MeV 5.23.10-2 1.37 . 10 9 0.72 . 10 8

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Angular distribution

0.01 0.02 0.03 0.04

10 30 50 70 90 Angles (degree) Neutron Fluence ((neutrons-Sr-1)/e-) 1 GeV 150 MeV

♦ Giant dipole resonance (GDR), neutrons are produced by photons with energies from threshold energy to 30 MeV ♦ Quasi-deuteron effect (QD) 30 < E < 140 MeV ♦ Photo-pion production above 140 MeV

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Energy Spectrum

      − = T E T E dE dN

n n n

exp

Energy distribution of neutrons produced from 1 GeV electrons incidents on 60g/cm2 thickness of different targets; circles represent simulation data while solid lines represent fittings of such data using Eq

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Mean energy of neutrons

0.00E+00 1.00E-02 2.00E-02 3.00E-02 4.00E-02 5.00E-02 6.00E-02 7.00E-02 8.00E-02 2 4 6 8 10 12 Thickness (cm) Neutron Fluence((neutron-cm-2)/e-) W Ta Pb

0.00E+00 1.00E-02 2.00E-02 3.00E-02 4.00E-02 5.00E-02 6.00E-02 7.00E-02 8.00E-02 9.00E-02 1.00E-01 2 4 6 8 10 12 Thickness (cm) Neutron Energy Fluence((MeV-cm-2)/e-) W Ta Pb

target Electron beam energy neutron Mean energy (MeV) Tungsten (W) Z=74, D=19.24 1GeV 1.64 150MeV 1.58 Tantalum (Ta) Z=73, D=16.4 1GeV 1.41 Lead (Pb) Z=82, D=11.34 1GeV 2.24

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Calculated Nuclear Temperature T.

Target Nuclear Temperature T (MeV) Tungsten (W) 0.44 Tantalum (Ta) 0.57 Lead (Pb) 0.98

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Conclusion

♦ GeV class Plasma accelerators can deliver pulsed Neutrons higher than 150 MeV electrons (2.2 Χ 10 8) neutrons/s. ♦ Tungsten (W) is the best target for neutron production. ♦ Neutrons mean energy ranged from 1.4 - 2.24 MeV ♦ Over 23% in forward direction from the peaked forward angular distribution ♦ The Ultra Short Pulsed Neutrons (tens femto second) can be used in lab scale TOF for elemental and isotopic identification with minimum signal to noise Ratio ♦The peak forward angular distribution can support linear design of TOF unit

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