Centro Nacional de Aceleradoreshttps://hdl.handle.net/11441/109382024-03-29T15:17:55Z2024-03-29T15:17:55ZDescription of continuum structures in a discrete basis: Three-body resonances and two-nucleon decayshttps://hdl.handle.net/11441/1447012024-02-14T11:31:20Z2020-01-01T00:00:00ZDescription of continuum structures in a discrete basis: Three-body resonances and two-nucleon decays
Weakly bound and unbound three-body nuclei are studied by using the pseudostate
method within the hyperspherical formalism. After introducing the theoretical framework, the method is applied first to the 9Be nucleus, showing a good agreement with the
available data for its low-lying dipole response. Then, recent results on the structure and
decay of the two-neutron emitters 26O and 16Be are presented. In particular, the role of
the n-n correlation in shaping their properties is discussed.
2020-01-01T00:00:00ZA rotary and reciprocating scintillator based fast-ion loss detector for the MAST-U tokamakhttps://hdl.handle.net/11441/1445832024-02-13T22:00:33Z2018-01-01T00:00:00ZA rotary and reciprocating scintillator based fast-ion loss detector for the MAST-U tokamak
The design and unique feature of the first fast-ion loss detector (FILD) for the Mega Amp Spherical
Tokamak - Upgrade (MAST-U) is presented here. The MAST-U FILD head is mounted on an axially and angularly actuated mechanism that makes it possible to independently adapt the orientation
[0◦
, 90◦
] and radial position [1.40 m, 1.60 m] of the FILD head, i.e., its collimator, thus maximizing
the detector velocity-space coverage in a broad range of plasma scenarios with different q95. The 3D
geometry of the detector has been optimized to detect fast-ion losses from the neutral beam injectors.
Orbit simulations are used to calculate the strike map and predict the expected signals. The results show
a velocity-space range of [4 cm, 13 cm] in gyroradius and [30◦
, 85◦
] in pitch angle, covering the entire
neutral beam ion energy range. The optical system will provide direct sight of the scintillator and simultaneous detection with two cameras, giving high spatial and temporal resolution. The MAST-U FILD
will shed light on the dominant fast-ion transport mechanisms in one of the world’s two largest spherical
tokamaks through absolute measurements of fast-ion losses.
2018-01-01T00:00:00ZAccelerator Mass Spectrometry (AMS) in Radioecologyhttps://hdl.handle.net/11441/1429542024-02-13T09:20:21Z2018-01-01T00:00:00ZAccelerator Mass Spectrometry (AMS) in Radioecology
Accelerator Mass Spectrometry (AMS) provides with an excellent sensitivity for the determination of
radionuclides in the environment. In fact, conventional radiometric techniques can hardly compete with
AMS in the solution of many problems involving the measurement of very low levels of radioactivity in
Nature. For that reason, during the last years AMS has become a powerful tool for Radioecology studies.
In this paper a review is done on the evolution of AMS applications to the measurement of environmental
radioactivity and, therefore, its contribution to the understanding of radionuclide behavior in Nature.For that,
the advantages of using AMS to determine key nuclides as 129I, 14C, Pu-isotopes and others in different
natural compartments will be discussed. The content of the paper is illustrated with the contributions to these
studies of the Spanish National Center for Accelerators (CNA) AMS systems.
2018-01-01T00:00:00ZImplications of the Harmonization of [18F]FDG-PET/CT Imaging for Response Assessment of Treatment in Radiotherapy Planninghttps://hdl.handle.net/11441/1342092024-02-14T19:16:46Z2022-01-01T00:00:00ZImplications of the Harmonization of [18F]FDG-PET/CT Imaging for Response Assessment of Treatment in Radiotherapy Planning
The purpose of this work is to present useful recommendations for the use of [18F]FDG-PET/CT imaging in radiotherapy planning and monitoring under different versions of EARL accreditation for harmonization of PET devices. A proof-of-concept experiment designed on an anthropomorphic phantom was carried out to establish the most suitable interpolation methods of the PET images in the different steps of the planning procedure. Based on PET/CT images obtained by using these optimal interpolations for the old EARL accreditation (EARL1) and for the new one (EARL2), the treatment plannings of representative actual clinical cases were calculated, and the clinical implications of the resulting differences were analyzed. As expected, EARL2 provided smaller volumes with higher resolution than EARL1. The increase in the size of the reconstructed volumes with EARL1 accreditation caused high doses in the organs at risk and in the regions adjacent to the target volumes. EARL2 accreditation allowed an improvement in the accuracy of the PET imaging precision, allowing more personalized radiotherapy. This work provides recommendations for those centers that intend to benefit from the new accreditation, EARL2, and can help build confidence of those that must continue working under the EARL1 accreditation.
2022-01-01T00:00:00Z