An implanted 4He target for experiments with radioactive beams

Weissman, L.; Raabe, R.; Huýse, M.; Koops, Gej; Pattyn, Hugo; Terwagne, G.; Duppen, P. Van

doi:10.1016/s0168-583x(00)00167-1

Cited by 10 publications

(12 citation statements)

References 24 publications

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“…We do not confirm the suggested loss of helium discussed in Ref. [14]. The aluminum areal density was measured using RBS of the oxygen beam to be 1.40 ± 0.1 × 10 19 atoms/cm 2 , which confirmed the manufacturer's quoted foil thickness of 600 µg/cm 2 .…”

Section: Target Tests and Resultscontrasting

confidence: 78%

“…Note that neglecting to consider the Jacobian = dΩ cm dΩ Lab (Θ) for p + He scattering (of the order of 0.5) led to the wrong conclusion that only 50% of the implanted helium dose is retained in the target [14]. The cross section dσ dΩ cm (Θ) is either the calculated RBS cross section when appropriate, or the measured cross section for p + 27 Al [15,16], p + 3 He [17], or the cross section calculated from the measured phase shifts of the elastic scattering of p + 4 He [18].…”

Section: Target Tests and Resultsmentioning

confidence: 99%

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In beam tests of implanted helium targets

et al. 2006

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Targets consisting of 3,4 He implanted into thin aluminum foils (approximately 100, 200 or 600 µg/cm 2 ) were prepared using intense (a few µA ) helium beams at low energy (approximately 20, 40 or 100 keV). Uniformity of the implantation was achieved by a beam raster across a 12 mm diameter tantalum collimator at the rates of 0.1 Hz in the vertical direction and 1 Hz in the horizontal direction. Helium implantation into the very thin (approximately 80-100 µg/cm 2 ) aluminum foils failed to produce useful targets (with only approximately 10% of the helium retained) due to an under estimation of the range by the code SRIM. The range of low energy helium in aluminum predicted by Northcliffe and Shilling and the NIST online tabulation are observed on the other hand to over estimate the range of low energy helium ions in aluminum. An attempt to increase the amount of helium by implanting a second deeper layer was also carried out, but it did not significantly increase the helium content beyond the blistering limit ( 6 × 10 17 atoms/cm 2 ).The implanted targets were bombarded with moderately intense 4 He and 16 O beams of 50-100 particle nA . Rutherford Back Scattering of 1.0 and 2.5 MeV proton beams and recoil helium from 15.0 MeV oxygen beams were used to study the helium content and profile before, during and after bombardments. We observed the helium content and profile to be very stable even after a prolonged bombardment (up to two days) with moderately intense beams of 16 O or 4 He. Helium implanted into thin (aluminum) foils is a good choice for thin helium targets needed, for example, for a measurement of the 3 He(α, γ) 7 Be reaction and the associated S 34 astrophysical cross section factor (S-factor).

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Section: Target Tests and Resultscontrasting

confidence: 78%

Section: Target Tests and Resultsmentioning

confidence: 99%

In beam tests of implanted helium targets

et al. 2006

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“…The resulting spectroscopic factors were used to put new limits to the contribution of low-energy resonances to the rate of 18 F(p,α) 15 O [45].…”

Section: Further Measurementsmentioning

confidence: 99%

Radioactive ion beam physics at the cyclotron research centre Louvain-la-Neuve

Huyse¹,

Raabe²

2011

J. Phys. G: Nucl. Part. Phys.

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Abstract.The first beam of post-accelerated radioactive ions was realized in 1989 at the Louvainla-Neuve research facility. The method employed two coupled cyclotrons to produce, separate and re-accelerate the species of interest. Several technological challenges were solved in the process, to obtain pure and intense beams for use in nuclear physics research. Similarly, new techniques were developed and refined for the measurement of the nuclear reactions induced by the radioactive beams. The available energy range made the facility particularly suited for nuclear astrophysics studies, and important results were obtained in the determination of stellar reaction rates using beams of 7 Be, 13 N, 18 F, 18,19 Ne. A beam of 6 He ions was extensively used in studies of the nuclear structure (halos, molecular states) and dynamics (the reaction process at energies around the potential barrier).

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“…To overcome this problem, an elegant solution was found for hydrogen targets in the form of polymers as polypropylene or polyethylene . However, in the case of reactions involving radioactive beams and He, as He does not form any chemical compounds, other solutions must be explored.…”

Section: Introductionmentioning

confidence: 99%

“…17 To overcome this problem, an elegant solution was found for hydrogen targets in the form of polymers as polypropylene or polyethylene. 18 However, in the case of reactions involving radioactive beams and He, as He does not form any chemical compounds, other solutions must be explored. The major requirements for a solid He target to be used in nuclear reactions are high He concentration (especially in the case of interaction with exotic nuclei that have very low beam current) and homogeneity versus depth, as well as high stability of the bulk He concentration versus time.…”

Section: ■ Introductionmentioning

confidence: 99%

Characterization and Validation of a-Si Magnetron-Sputtered Thin Films as Solid He Targets with High Stability for Nuclear Reactions

et al. 2016

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In this work, we present our magnetron sputtering based methodology to produce amorphous silicon coatings with closed porosity, as a strategy to fabricate solid helium targets, in the form of supported or self-supported thin films, for nuclear reactions. We show how by changing the He working pressure it is possible to obtain highly porous homogeneous structures incorporating different He amounts. These porous coatings (a-Si:He) are very reproducible from run to run, and the high He amount incorporated makes them excellent candidates for solid He targets. The possibility of producing self-supported films is illustrated here, and its potential use in inverse kinematics experiments with radioactive beams is shown through the dispersion in forward geometry of a stable 6 Li beam. Also the elastic scattering cross-sections for proton from helium were determined using an a-Si:He coating. The results agree well with the ones reported in the literature. These two examples validate our coatings as good candidates to be used as solid He targets in nuclear reactions. The stability of He inside the coatings, fundamental for its use as solid He targets, was investigated, both over time and after irradiation. The coatings proved to be very stable, and the amount of He inside the pores remains unaltered at least 2 years after deposition and after high irradiation fluence (5 × 10 17 particles/cm 2 ; with a dose rate of 5 × 10 12 particles/(cm 2 s)).

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An implanted 4He target for experiments with radioactive beams

Cited by 10 publications

References 24 publications

In beam tests of implanted helium targets

In beam tests of implanted helium targets

Radioactive ion beam physics at the cyclotron research centre Louvain-la-Neuve

Characterization and Validation of a-Si Magnetron-Sputtered Thin Films as Solid He Targets with High Stability for Nuclear Reactions

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