Measurement of the absolute cross section of the 3He(4He, γ)7Be reaction at Ec.m. = 525 keV

doi:10.1016/0375-9474(84)90229-X

Nuclear Physics A

Volume 427, Issue 3, 15 October 1984, Pages 526-544

https://doi.org/10.1016/0375-9474(84)90229-X Get rights and content

Abstract

The cross section for the radiative capture reaction ³He(⁴He, γ)⁷Be has been measured at 525 keV in the centre-of-mass by detection of prompt capture γ- rays. The targets were ³He-implanted Nb foils that allowed us to circumvent the experimental difficulties inherent in the use of extended gas cells for absolute measurements. The results give an inferred zero-energy cross-section factor of S₃₄(0) = 0.47 ± 0.04 keV · b. The present result is compared with results from previous capture γ-ray yield and ⁷Be-activity methods of measuring the cross-section factor.

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Citation Excerpt :
The achievable target thickness (the number of target atoms per unit area) is limited by the maximum number of implanted atoms the backing can hold (e.g., due to the blistering effect [22]). The determination of the target thickness is rather difficult and care must be taken to preserve the target stability under beam bombardment [3]. This problem is especially severe for noble gas atoms which can diffuse out easily from the backing [23].
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Citation Excerpt :
One could therefore consider self-supporting targets comprised of binary compounds such as CdS, AgS, HgS or SbS, although natural isotopic sulfur abundances would be the norm. Noble gases cannot typically be used in a solid target geometry at room temperature unless they are embedded in a suitable host; for example, 3He has been successfully implanted at 35 keV to a large fluence (3 μg/cm2) into bulk Nb (foil thickness ∼125 μm) to investigate the 3He(4He,γ)7Be reaction [9]. Obviously for absolute cross section measurements, the implanted ion (i.e. target) areal density should be as large as possible in order to simulate the experimental situations normally encountered with elemental (or binary compound) films.
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^∗: On leave from GSI, D-61 Darmstadt, Federal Republic of Germany.

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Nuclear Physics A

Abstract

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Activation measurement of the he3(α,γ)be7 reaction cross section at high energies

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Thin-window gas cell target for activation cross-section measurements relevant for nuclear astrophysics

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