A digital twin for 64Cu production with cyclotron and solid target system

Abstract

One method for finding reliable and cost-effective solutions for designing radioisotope production systems is represented by the "digital twin" philosophy of design. Looking at cyclotron solid targets, uncertainties of the particle beam, material composition and geometry play a crucial role in determining the results. The difference between what has been designed and what can be effectively manufactured, where processes such as electroplating are poorly controllable and generate large non-uniformities in deposition, must also be considered. A digital twin, where the target geometry is 3D scanned from real models, can represent a good compromise for connecting "ideal" and "real" worlds. Looking at the ⁶⁴Ni(p,n)⁶⁴Cu reaction, different Unstructured-Mesh MCNP6 models have been built starting from the 3D solid target system designed and put into operation by COMECER. A characterization has been performed considering the designed ideal target and a 3D scan of a real manufactured target measured with a ZEISS contact probe. Libraries and physics models have been also tested due to limited cross-section data. Proton spectra in the target volume, 3D proton-neutron-photon flux maps, average energies, power to be dissipated, shut-down dose-rate, ⁶⁴Cu yield compared with various sources of experimental data and beam axial shifting impact, have been estimated. A digital twin of the ⁶⁴Ni(p,n)⁶⁴Cu production device has been characterized, considering the real measured target geometry, paving the way for a fully integrated model suitable also for thermal, structural or fluid-dynamic analyses.

Figure 1

Panel (A), irradiation unit (PTS). Panel (B), TADDEO-PRF. Panel (C), coupling with two different PTS and a reference cyclotron. Panel (D), EDS. Panel (E), cooling system.

Figure 2

Panel (A), real target scanning results. Panel (B), Above, shuttle prospective view. Below, target’s planar view. Left, ideal model. Center, 3d scan of the effective target, showing also the irregular pattern, as transferred to the Monte Carlo Model (with some computational limits on the discretization of the geometric domain). Right, real target.

Figure 3

MCNP geometry details. Above, center: MCNP model of the whole PTS unit. Above, left: magnification of the coupling parts between the beamline extraction channel and the PTS (water cooling circuits and the so-called honeycomb supporting structure are visible together with the degrader foil). Above, right, shuttle hosting the target. Below, from left to right: ideal and real target as modeled in MCNP. Cut plane at the proton beamline and target axis is shown.

Figure 4

Proton spectra in the target volume. Y axis, intensity [a.u.], X axis, energy [MeV]. As it can be seen, from the ideal and the real target, the tallied spectra remain coherent between models and cross sections.

Figure 5

Panel (A), cut view along the proton beamline (See Fig. 2 for details of the 3D model and the cut plane). Panel (B), proton flux, arbitrary units. CEM03.03 model only taken as reference. Left, ideal target; Right, real target. Planar and PTS relevant section views are displayed. Panel (C), axial misalignment sensitivity analysis and comparison with a typical COMECER paper burn experimental result. The honeycomb supporting structure shadow is clearly visible (see also Supplementary Figure S1 and Fig. 3 for details).

Figure 6

Panel (A), photon flux, arbitrary units. CEM03.03 model only taken as reference. Left, ideal target; Right, real target. Above, PTS relevant parts section; Below, zoom around the target region. Panel (B), neutron flux, arbitrary units. CEM03.03 model only taken as reference. Left, ideal target; Right, real target. Above, PTS relevant parts section; Below, zoom around the target region.

Figure 7

Left, ⁶⁴Cu yield estimated with cross sections and model physics for ideal and real targets. Red band indicates the values experimentally found by COMECER with the ALCEO system mounted on cyclotron beam ports (the higher the color intensity, the higher the frequency of the experimentally found activity; color band centered on the 2.5 value). The green band instead is referred to a PTS device directly interfaced with the beam line. Right, experimental data obtained by COMECER. Chart showing results for beam line (blue) and beam port (orange) together with experimental values (dots), mean (cross), local minimum and maximum (horizontal rays) and the rectangle showing median and 25th-75th percentiles as in the usual “Box and Whisker” representation. Y axis, mCi μA⁻¹ h⁻¹.

Figure 8

Normalized shut-down dose-rate from the end of beam up to 72 h. Red, ideal target. Yellow, real target. Y-scale in arbitrary units. X axis, time [h].