Laser-driven particle and photon beams and some applications

Outstanding progress has been made in high-power laser technology in the last 10 years with laser powers reaching petawatt (PW) values. At present, there are 15 PW lasers built or being built around the world and plans are afoot for new, even higher power, lasers reaching values of exawatt (EW) or even zetawatt (ZW) powers. Petawatt lasers generate electric fields of 10(12) Vm(-1) with a large fraction of the total pulse energy being converted to relativistic electrons with energies reaching in excess of 1 GeV. In turn these electrons result in the generation of beams of protons, heavy ions, neutrons and high-energy photons. These laser-driven particle beams have encouraged many to think of carrying out experiments normally associated with conventional nuclear accelerators and reactors. To this end a number of introductory articles have been written under a trial name `Laser Nuclear Physics' (Ledingham and Norreys 1999 Contemp. Phys. 40 367, Ledingham et al 2002 Europhys. News. 33 120, Ledingham et al 2003 Science 300 1107, Takabe et al 2001 J. Plasma Fusion Res. 77 1094). However, even greater strides have been made in the last 3 or 4 years in laser technology and it is timely to reassess the potential of laser-driven particle and photon beams. It must be acknowledged right from the outset that to date laser-driven particle beams have yet to compete favourably with conventional nuclear accelerator-generated beams in any way and so this is not a paper comparing laser and conventional accelerators. However, occasionally throughout the paper as a reality check, it will be mentioned what conventional nuclear accelerators can do

Strongly enhanced Li + D reaction in Pd observed in deuteron bombardment on PdLi with energies between 30 and 75 keV

Thick target yields of α particles emitted in the 6,7Li(d,α)4,5He reactions in PdLix and AuLix were measured as a function of the bombarding energy between 30 and 75 keV. It was found that the reaction rate in Pd at lower energies is enhanced strongly over the one predicted by the cross section for the reaction with bare nuclei, but no enhancement is observed in Au. A screening energy is introduced to reproduce the excitation function of the thick target yield for each metal. The deduced value for Pd amounts to 1500±310 eV, whereas it is only 60±150 eV for Au. The enhancement in the Pd case cannot be explained by electron screening alone but suggests the existence of an additional and important mechanism of screening in metal

Neutron-induced reactions contributing to the background in γ-ray astrophysics missions

Nuclear reactions induced by neutrons lead to the delayed emission of γ rays contributing to the instrumental background in γ-ray astrophysics missions in space. The cross sections for the reactions 27Al(n,2p)26Na, 27Al(n,α)24Na, and 56Fe(n,p)56Mn were measured up to a neutron energy of 50 or 65 MeV. A simple model was developed that allows one to extrapolate cross sections to higher energies. The magnitude of the instrumental background lines induced in the detectors of ESA's future INTEGRAL mission is deduced from our measurements.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Measurement of cross-sections for the 9Be(n,3n)7Be and 56Fe(n,p)56Mn reactions producing background lines in γ-ray astrophysics

The reactions 9Be(n,3n)7Be and 56Fe(n,p)56Mn were measured between 28 and 68 MeV and at 28 MeV, respectively. These reactions lead to the emission of γ-rays (478, 847, 1811 keV) that may be disturbing in γ-ray astrophysics missions. Consequences regarding the induced background in detectors are drawn. © 1998 Elsevier Science B.V. All rights reserved.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Measurement of the 13N +12,13C elastic scattering

info:eu-repo/semantics/publishe

Neutron induced background in the γ-ray lines of astrophysical interest

Neutrons produced close to the Ge detectors of SPI can induce nuclear reactions, leading to the emission of β-delayed γ-rays, which is a possible cause of background in the γ-ray lines of astrophysical interest © 1999 OPA (Overseas Publishers Association) N.V. Published by license under the Gordon and Breach Science Publishers imprint.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Measurement of resonance widths in 20Na using the 19Ne + p elastic scattering

info:eu-repo/semantics/publishe

One-step energy scanning of wide low-lying 1- resonances in 13C+p and 13N+p scattering

Thick polyethylene targets have been bombarded with 8.2 MeV 13C and 13N beams accelerated by a cyclotron, i.e. having a relatively large energy spread of about 200 keV. Recoil protons have been detected in order to observe the Jπ=1- wide resonances at E*=8.06 and 5.17 MeV in the 14N and 14O compound nuclei, respectively. It is shown that accurate values of the energy, width and spin of the resonant states can be obtained under experimental conditions which, at first glance, may seem inappropriate. The method is well suited for resonance studies using radioactive beams. The measured width of the 14N resonance (Λ=33.7±1.0 keV) disagrees with a recent measurement (Λ=23 keV). The energy of the 14O resonance was determined to be Ec.m.=526±3 keV instead of 545±10 keV as quoted in the literature. A new paramater-free microscopic calculation was undertaken to solve an apparent discrepancy between the experimental proton width and a previous calculation. © 1992.info:eu-repo/semantics/publishe

Measurement of the 13N + 12,13C elastic scatterings

info:eu-repo/semantics/publishedNucleus-Nucleus Collisions, Taormina, Italy, 30 May - 4 June 1994, edited by Massimo Di Toro, Emilio Migneco and Paolo Piattell

Production, acceleration and use of radioactive ion beams at Louvain-la-Neuve

The production and acceleration of radioactive beams using two cyclotrons coupled by an electron cyclotron resonance ion source is described. Pure beams of 13N(T 1 2 = 9.96 min) and 19Ne(T 1 2 = 17 s) with an energy around 1 MeV/amu are obtained with intensities larger than 50 ppA. As an example, cross section measurements using a 13N beam on hydrogen and deuteron targets are presented. Finally, the ARENAS3 project, a future plan for the production of radioactive beams in Belgium, is described. © 1992.SCOPUS: ar.jinfo:eu-repo/semantics/publishe