LIEBE Design optimisation of the irradiation release chambers

Motivation Main Results Summary Context; LIEBE Project Current liquid targets at CERN-ISOLDE Motivation … 172 Hg 231 μs … 176 Hg 177 Hg 20. 3 ms 118 ms … 196 Hg STABLE … 30 -60 k. V Loop-type target concept proposed in EURISOL DS effusion Protons 2 Hg 177 118 ms diffusion § Slow release of Hg isotopes 10 s § Heat dissipation CERN-ISOLDE < 6 k. W EURISOL 100 k. W Copyright © 2016 SCK • CEN

Motivation Main Results Summary Irradiation volume Objectives Hg 177 118 ms § Complete evacuation of the irradiated LBE into droplets within 100 ms § Uniform distribution of droplet formation along the length of the target § Formation of small droplets (r ~ 100 μm) Methodology 3 § Initial basic geometries § CFD analysis LBE flow in irradiation volume § Progressive geometrical adjustments Results l Parallelepiped-shape feeder volume D. Houngbo et al. , NIMA 777 (2015) 202 -210 l Prism-shape feeder volume Copyright © 2016 SCK • CEN

Motivation Main Results Summary Context; LIEBE Project Current liquid targets at CERN-ISOLDE Loop-type target concept proposed in EURISOL DS Hg 177 118 ms 30 -60 k. V effusion Protons 4 diffusion § Slow release of Hg isotopes 10 s § Heat dissipation CERN-ISOLDE < 6 k. W EURISOL 100 k. W Copyright © 2016 SCK • CEN

Motivation Main Results Summary The release model Results Objective § Assessment of the release efficiency for short lived Hg isotopes Methodology l Effusion model developed l Simplifications required to deal with the complex geometry l Analytical release model developed l Validated on ISOLDE data (static-bath targets) Diffusion Effusion Overall delay time distribution [a. u. ] Evacuation Time [s] 5 Copyright © 2016 SCK • CEN

Motivation Main Results Summary The release model – Method validation Results Objective l Hg out of a liquid Pb bath target § Validation of the methodology used to derive the release model § Comparison between computed and experimental results l Li out of a solid Ta target L. Egoriti, S. Boeckx, L. Ghys, D. Houngbo, L. Popescu, NIM 832 (2016) 202 -207 6 Copyright © 2016 SCK • CEN

Motivation Main Results Summary Release volume - Optimization Results Objectives Hg 177 118 ms § Study of the influence of several design parameters on this release efficiency § Identification of more efficient designs for the release volume 2. 02 % Methodology § Application of the model to predict release efficiencies of 177, 178 Hg in initial geometry § Study separately the geometrical design parameters 9. 6 % § Application of the model to the resulting geometry 7 Copyright © 2016 SCK • CEN

Motivation Main Results Summary Shock-wave analysis Heat Deposition [Ge. V/cm 3. p] Max ∆T

Motivation Main Results Summary l Optimized geometries for irradiation & release volume Hg 177 118 ms l Some of the findings incorporated in the LIEBE prototype Irradiation volume Release volume l Prototype under offline testing at CERN-ISOLDE 9 Copyright © 2016 SCK • CEN