Characterisation of natural and enriched oxygen targets in lithium carbonate foils

Papka, P.; Kheswa, N. Y.; Msimanga, M.; Pineda-Vargas, C.A.; Soić, N.

doi:10.1007/s10967-015-4046-0

Cited by 3 publications

(7 citation statements)

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“…The 510µg/cm 2 -thick nat Li 2 CO 3 target was prepared on a 50µg/cm 2 -thick 12 C backing. The total Li content was approximately 50-µg/cm 2 [12]. The solid-angle acceptance of the spectrometer (3.83 msr) was defined by a circular collimator with an opening angle ±2 • .…”

Section: Referencementioning

confidence: 99%

“…Such states should exist particularly at excitation energies near the separation energies to these clusters, as described by the Ikeda diagram [1]. The Hoyle state, the 0 + 2 state at E x = 7.654 MeV in 12 C, is considered the archetype of a state that exhibits α-particle structure, with one option being a 3α gas-like structure similar to a Bose-Einstein condensate consisting of three α-particles all occupying the lowest 0S state [2].…”

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confidence: 99%

“…The 0 + 6 state obtained from the calculation is 2 MeV above the four α-particle breakup threshold (S 4α = 14.437 MeV) and has a large radius of 5 fm, indicating a dilute density structure. Ohkubo and Hirabayashi showed in a study of α+ 12 C elastic and inelastic scattering [5] that the moment of inertia of the 0 + 6 state is drastically reduced, which suggests that it is a good candidate for the 4α cluster condensate state. Calculations performed with the Tohsaki-Horiuchi-Schuck-Röpke (THSR) α-cluster wave function [6] also support this notion with an estimated total width of 34 keV for the 0 + 6 state [7], much smaller than the experimentally determined value of 166(30) keV [8].…”

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confidence: 99%

“…(c): The raw (i), background subtracted (ii) and instrumental background inclusive excitation spectra (iii) from the Li2CO3 target. Spectrum (iv) is the background subtracted inclusive excitation spectrum from the 12 C target, normalised to spectrum (b) through the 9.641 (5) MeV resonance in 12 C. The linear fit of spectrum (c), used for background subtraction, is drawn in red. (d): The coincident matrix of silicon energy versus the excitation energy of the recoil nucleus for decay particles detected within the angular range: 156 • < θ lab < 163 • (two strips within the array).…”

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Characterization of the proposed 4−α cluster state candidate in O16

Neveling

Adsley

et al. 2017

Phys. Rev. C

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The16 O(α,α ′ ) reaction was studied at θ lab = 0• at an incident energy of E lab = 200 MeV using the K600 magnetic spectrometer at iThemba LABS. Proton decay and α decay from the natural parity states were observed in a large-acceptance silicon strip detector array at backward angles. The coincident charged-particle measurements were used to characterize the decay channels of the 0 Table I). The 0 the four-α-particle breakup threshold and has a large radius of 5 fm, indicating a dilute density structure. Ohkubo and Hirabayashi showed in a study of α + 12 C elastic and inelastic scattering [9] that the moment of inertia of the 0 + 6 state is drastically reduced, which suggests that it is a good candidate for the 4-α cluster condensate state. Calculations performed with the Tohsaki-Horiuchi-Schuck-Röpke (THSR) α-cluster wave function [10] also support this notion with an estimated total width of 34 keV for the 0 + 6 state [11], much smaller than the experimentally determined value of 166(30) keV [12].Recent unsuccessful attempts to measure particle decay widths of the 0 + 6 state in 16 O[17,18] highlighted the need for an experiment that combines α-particle decay measurements with a high-energy-resolution experimental setup and a reaction capable of preferentially populating 0 + states. In contrast to transfer reaction measurements, inelastic α-particle scattering at zero degrees has the advantage that it predominantly excites low-spin natural parity states. A measurement of the 16 O(α,α ′ ) reaction at zero degrees, coupled with coincident observations of the 16 O decay products, was performed at the iThemba Laboratory for Accelerator-Based Sciences (iThemba LABS) (7) 162 (

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confidence: 99%

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confidence: 99%

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Characterization of the proposed 4−α cluster state candidate in O16

Neveling

Adsley

et al. 2017

Phys. Rev. C

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“…The excited states in 16 O were identified using the focal plane detector system of the K600 magnetic spectrometer [8] and the coincident charged-particle decay was detected using a double-sided silicon strip detector (DSSSD) array known as the Coincidence Array for K600 Experiments (CAKE) [9] (see Figure 1). A 510-µg/cm 2 -thick nat Li 2 CO 3 target was used [10]. The target was prepared on a 50-µg/cm 2 -thick 12 C backing and the total Li content was approximately 50-µg/cm 2 .…”

Section: Experimental Methodsmentioning

confidence: 99%

Refuting The Nature Of The Sixth 0+ Hoyle-analogue State Candidate In 16O

Li¹,

Adsley²,

Neveling³

et al. 2017

Proceedings of the 26th International Nuclear Physics Conference — PoS(INPC2016)

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+ 6 state, previously observed at E x = 15.097(5) MeV. This state is identified by several theoretical cluster calculations to be a good candidate for the 4-α cluster state, analogous to the Hoyle state in 12 C. Whilst much theoretical work has been performed to reconcile a calculated α-cluster state with this resonance, the experimental information on this state remained very scarce. To investigate this state, the 16 O(α, α ) reaction was studied at θ lab = 0 • at an incident energy of E lab = 200 MeV using the K600 magnetic spectrometer at iThemba LABS. For the first time, the decay channels of the E x = 15.097(5) MeV state were isolated using a large acceptance silicon-strip detector array at backward angles. The lineshapes of the states were analysed within a phenomenological R-matrix framework. Results indicate the presence of a resonance at E x ≈ 15 MeV which does not exhibit a J π = 0 + nature.

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Deuterium retention in co-deposition with lithium in Magnum-PSI: experimental analysis and comparison with SOLPS-ITER

Morbey,

Gonzalez,

Arnoldbik

et al. 2024

Nucl. Fusion

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The vapor-box is a liquid metal based design to cope with the demanding conditions of the divertor. This design relies on the recirculation of lithium by evaporation and condensation. An issue to this approach is the safety risks of Li-D/T formation and co-deposition on both the vapor-box walls - leading to possible recirculation impedance- and on the first wall leading to unacceptable tritium retention. Additively manufactured tungsten Capillary Porous Structure (CPS) samples filled with Li were exposed to high heat flux D plasmas in the linear plasma device Magnum-PSI and Li-D co-deposition was measured as a function of substrate temperature, estimated to be in the range 200-428 ${^\circ}$C and distance between 25-85 mm to the plasma beam center. The D:Li ratio was determined via in-situ ion beam diagnostics (NRA and EBS) and the spectra analyzed simultaneously to maximise the precision of the measurement. The experimental results approach close to the theoretical maximum at 40:60 D:Li ratio and the thickness of the deposited films was 0.02 - 3.2 $\mu$m. For witness plate temperatures above 400 ${^\circ}$C Li films under 150 nm in thickness were deposited and show lower D:Li ratios, as low as 5:95 D:Li ratio. At these temperatures the evaporation rate from the WPs is close to the deposition rate, and the decomposition pressure for LiD becomes comparable to the operational pressure in the vessel during the discharge. SOLPS-ITER simulations were also conducted to complement the experimental data. The results were used to narrow the range of CPS surface temperature to between $650-700$^{\circ}$C and determined that the D$^{+}$ plasma is largely replaced by Li$^{+}$ plasma close to the target surface. Further, the redeposition ratio of the lithium on the CPS surface is determined to be around 80$\%$, which matches well with the value determined from a quartz crystal microbalance. Due to limitations in the modeling of neutral interactions with Li coated surfaces, the SOLPS-ITER modeling does not well recreate the observed Li and D deposition layers on the WPs, indicating that this aspect of the modeling in Eirene needs improvement to accurately model plasmas containing significant quantities of Li. However, SOLPS-ITER simulations should be extended to include LiD molecules and improve the accuracy of heat flux towards the target to improve the comparison with experimental data.

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Characterisation of natural and enriched oxygen targets in lithium carbonate foils

Cited by 3 publications

References 8 publications

Characterization of the proposed 4−α cluster state candidate in O16

Characterization of the proposed 4−α cluster state candidate in O16

Refuting The Nature Of The Sixth 0+ Hoyle-analogue State Candidate In 16O

Deuterium retention in co-deposition with lithium in Magnum-PSI: experimental analysis and comparison with SOLPS-ITER

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