摘要
Laser-driven neutron sources could offer a promising alternative to those based on conventional accelerator technologies in delivering compact beams of high brightness and short duration.We examine this through particle-in-cell and Monte Carlo simulations that model,respectively,the laser acceleration of protons from thin-foil targets and their subsequent conversion into neutrons in secondary lead targets.Laser parameters relevant to the 0.5 PW LMJ-PETAL and 0.6–6 PW Apollon systems are considered.Owing to its high intensity,the 20-fs-duration 0.6 PW Apollon laser is expected to accelerate protons up to above 100MeV,thereby unlocking efficient neutron generation via spallation reactions.As a result,despite a 30-fold lower pulse energy than the LMJ-PETAL laser,the 0.6 PW Apollon laser should perform comparably well both in terms of neutron yield and flux.Notably,we predict that very compact neutron pulses,of∼10 ps duration and∼100μm spot size,can be released provided the lead convertor target is thin enough(∼100μm).These sources are characterized by extreme fluxes,of the order of 10^(23) n cm^(−2) s^(−1),and even ten times higher when using the 6 PW Apollon laser.Such values surpass those currently achievable at large-scale accelerator-based neutron sources(∼10^(16) n cm^(−2) s^(−1)),or reported from previous laser experiments using low-Z converters(∼10^(18) n cm^(−2) s^(−1)).By showing that such laser systems can produce neutron pulses significantly brighter than existing sources,our findings open a path toward attractive novel applications,such as flash neutron radiography and laboratory studies of heavy-ion nucleosynthesis.
基金
This work was supported by the European Research Council(ERC)under the European Union’s Horizon 2020 research and innovation program(Grant Agreement No.787539)
It was also supported by Grant No.ANR-17-CE30-0026-Pinnacle from the Agence Nationale de la Recherche
We acknowledge GENCI,France,for granting us access to HPC resources at TGCC/CCRT(Allocation No.A0010506129)
S.N.C.acknowledges support from the Extreme Light Infrastructure Nuclear Physics(ELI-NP)Phase II,a project co-financed by the Romanian Government and the European Union through the European Regional Development Fund-the Competitiveness Operational Programme(1/07 July 2016,COP,ID 1334)
by the project ELI-RO-2020-23 funded by IFA(Romania)
The PETAL laser was designed and constructed by CEA under the financial auspices of the Conseil Régional d’Aquitaine,the French Ministry of Research,and the European Union
The CRACC diagnostic was designed and commissioned on the LMJ-PETAL facility as a result of the PETAL+project coordinated by University of Bordeaux and funded by the French Agence Nationale de la Recherche under Grant No.ANR-10-EQPX-42-01
The LMJ-PETAL experiment presented in this article was supported by the Association Lasers et Plasmas and by CEA
The diagnostics used in the experiment have been realized in the framework of the EquipEx PETAL+via Contract No.ANR-10-EQPX-0048.
