EURISOL DS Progress Meeting T2-03, CEA Saclay, France 27 – 28 October, EURISOL DS PROJECT Task#2: MULTI-MW TARGET DESIGN Adonai Herrera-Martínez & Yacine Kadi on behalf of T2 European Organization for Nuclear Research, CERN CH-1211 Geneva 23, SWITZERLAND

EURISOL DS Progress Meeting T2-03, CEA Saclay, France 27 – 28 October, Overview 1.Baseline Parameters 2.Baseline Design (BLD) vs. Hg Jet (Hg-J) → Intermediate Solution (IS) 3.Comparison of the FLUKA Simulation Results –Primary Particle Flux → Proton Escapes –Neutron Flux and Energy Spectra –Fission Densities → Isotopic Yields –Energy Deposition → Temperature Increase 4.Conclusions

EURISOL DS Progress Meeting T2-03, CEA Saclay, France 27 – 28 October, Sensitivity Study

EURISOL DS Progress Meeting T2-03, CEA Saclay, France 27 – 28 October, Baseline Parameters of the MMW Hg Target ParameterSymbolUnitsNvalRange Converter Target materialZ conv -Hg (liquid)LBE Secondary Target materialZ targ -UC x, BeO Beam particlesZ beam -ProtonDeuteron Beam particle energyE beam GeV1  2 Beam currentI beam mA42 – 5 Beam time structure--dcac 50Hz 1ms pulse Gaussian beam geometrys beam mm15  25, parabolic Beam powerP beam MW4  5 Converter lengthl conv cm45  85 Converter radius (cylinder)r conv cm158 – 20 Hg temperatureT conv ºC150 (tbc)< 357 Hg flow rateQ conv kg/s200 (tbc)< 3000 Hg speedV conv m/s2 (tbc)< 30 Hg pressure dropΔP1ΔP1 bartbc<< 100 Hg overpressureΔ P 2 bartbc<< 100 UC x temperatureT targ ºC – 2500

EURISOL DS Progress Meeting T2-03, CEA Saclay, France 27 – 28 October, MMW Hg Target Configuration BLD: Shape of Hg target optimised for neutron production (neutron balance) 15 mm sigma proton beam, fully contained in the Hg target Possibility of further reduction in Hg target dimensions → Intermediate solution (IS) Hg Target Reflector Target container UCx/BeO Target Protons 73 cm 30 cm Protons Reflector Hg Jet UCx/BeO Target 40 cm 4 cm Hg-J: designed for high-energy neutron fluxes in the U nat C 3 (3 g/cm 3 ) fission target 4 mm sigma proton beam, mostly contained in the 4 cm diameter Hg Jet Use of reflector to improve neutron economy and to shield HE particles Hg Target Reflector Target container UCx/BeO Target Protons 68 cm 16 cm

EURISOL DS Progress Meeting T2-03, CEA Saclay, France 27 – 28 October, Primary Proton Flux Distribution Primary flux (prim/cm 2 /s/MW of beam) 1GeV proton range ~ 46 cm BLD: Beam fully contained inside Hg-J: Important HE primary escapes (~10 13 prim/cm 2 /s/MW of beam), mostly at small polar angles (up to 25% losses)→ Beam dump IS: Some primary escapes through the endcap, mostly contained by the reflector BLD and IS: Beam window suffering ~100 μA/cm 2 /MW (radiation damage limit)

EURISOL DS Progress Meeting T2-03, CEA Saclay, France 27 – 28 October, Neutron Flux Distribution Neutron flux (n/cm 2 /s/MW of beam) Neutron fluxes in the fission target ~10 14 n/cm 2 /s/MW of beam BDL and IS: Partial containment by the reflector of the escaping neutron flux Hg-J: Higher neutron flux in the fission target (~2×10 14 n/cm 2 /s/MW of beam)

EURISOL DS Progress Meeting T2-03, CEA Saclay, France 27 – 28 October, Significantly harder spectrum for the Hg-J, with a peak neutron energy between 1 − 2 MeV, compared to 300 keV for BLD and 700 keV for IS Very low fission cross-section in 238 U below 2 MeV (~10 -4 barns). Optimum energy: 35 MeV Use of natural uranium:  f in 235 U (0.7% wt.): at least 2 barns Further gain if neutron flux is reflected (e.g. BeO) Neutron Energy Spectrum vs Fission Cross-Section in Uranium

EURISOL DS Progress Meeting T2-03, CEA Saclay, France 27 – 28 October, Fission Density Distribution in U nat C 3 Fission density (fissions/cm 3 /s/MW of beam) High-energy fissions in Hg → Radioactive isotopes in Hg BLD: fiss/cm 3 /s/MW, homogenously distributed Hg-J: High and anisotropic fission density (~4×10 11 fiss/cm 3 /s/MW) IS: 2×10 11 fiss/cm 3 /s/MW, homogenously distributed → ~10 15 fissions/s for 4 MW of beam and a 1 litre U nat C 3 (3 g/cm 3 ) fission target

EURISOL DS Progress Meeting T2-03, CEA Saclay, France 27 – 28 October, HE Fission Density Distribution in U nat C 3 Non-homogenous HE fissions in all cases BLD: ~10% of the fissions are HE (>20 MeV), compared to ~20% in IS and ~40% in Hg-J HE fission density (fissions[>20 MeV]/cm 3 /s/MW of beam)

EURISOL DS Progress Meeting T2-03, CEA Saclay, France 27 – 28 October, LE Fission Density Distribution in U nat C 3 LE fission density (fissions[<20 MeV]/cm 3 /s/MW of beam) BLD: LE fissions account for 90% of the radial fissions BDL and IS: Important effect of the reflector ← More LE fissions in the outside surface of the fission target Hg-J: Stronger anisotropy in the LE fissions and lack of containment for LE neutrons

EURISOL DS Progress Meeting T2-03, CEA Saclay, France 27 – 28 October, Maximum energy deposition in the first 10 cm beyond the interaction point, in Hg BLD and IS, maximum power density in Hg: ~2 kW/cm 3 /MW of beam Hg-J, maximum power density in Hg: ~22 kW/cm 3 /MW of beam! Power density in the U nat C 3 target: ~3 W/cm 3 /MW of beam in the BLD and ~5 W/cm 3 /MW the IS, homogenously distributed in both ~20 W/cm 3 /MW of beam U nat C 3 target for the Hg-J, following the fission density distribution → Strongly anisotropic Power Densities (1) Power density (W/cm 3 /MW of beam)

EURISOL DS Progress Meeting T2-03, CEA Saclay, France 27 – 28 October, Power Densities (2) Hg Beam Window More than one order of magnitude difference between the free surface Hg-J (~22 kW/cm 3 /MW) and the confined Hg targets (BLD, ~2 kW/cm 3 /MW) BDL and IS: Beam window suffering important power densities (~1 kW/cm 3 /MW → extra cooling plus radiation resistant material needed)

EURISOL DS Progress Meeting T2-03, CEA Saclay, France 27 – 28 October, Power Densities (3) Increasing  beam from 15 to 25 mm or taking parabolic beam of at least 45 mm radius → reduce  T in Hg by a factor Doubling the flow rate (~2 m/s) will reduce  T by factor 2 →  T ~ ºC

EURISOL DS Progress Meeting T2-03, CEA Saclay, France 27 – 28 October, Radioisotope Yields in U nat C 3 Target (1) Harder neutron spectrum for the Hg Jet → more high-energy neutron induced fissions → large increase in the symmetrical fission products Small differences in terms of asymmetrical (low energy) fission fragments

EURISOL DS Progress Meeting T2-03, CEA Saclay, France 27 – 28 October, Radioisotope Yields in the U nat C 3 (1) 28-Ni (A)Baseline designIntermediate solutionHg Jet 701.7E+052.9E E E+052.3E E E+052.9E E Ni isotopic yields (Ions/cm 3 /s/MW of beam) and ratio over BLD 31-Ga (A)Baseline designIntermediate solutionHg Jet 733.7E+059.8E E E+062.1E E E+062.8E E E+065.1E E E+076.2E E E+071.0E E E+077.4E E E+077.7E E Ga isotopic yields (Ions/cm 3 /s/MW of beam) and ratio over BLD

EURISOL DS Progress Meeting T2-03, CEA Saclay, France 27 – 28 October, Radioisotope Yields in the U nat C 3 (2) Ga isotopic yields (Ions/cm 3 /s/MW of beam) and ratio over BLD 31-Ga(A)Baseline designIntermediate solutionHg Jet 827.4E+063.1E E E+061.6E E E+068.9E E E+052.3E E Kr (A)Baseline designIntermediate solutionHg Jet 841.9E+065.4E E E+073.5E E E+071.2E E E+084.8E E E+091.8E E E+093.4E E E+094.8E E E+093.8E E E+092.4E E Kr isotopic yields (Ions/cm 3 /s/MW of beam) and ratio over BLD

EURISOL DS Progress Meeting T2-03, CEA Saclay, France 27 – 28 October, Radioisotope Yields in the U nat C 3 (3) Kr isotopic yields (Ions/cm 3 /s/MW of beam) and ratio over BLD 36-Kr (A)Baseline designIntermediate solutionHg Jet 935.5E+089.6E E E+083.8E E E+076.6E E E+075.3E E E+062.0E E E+064.0E E E+047.9E E Sn isotopic yields (Ions/cm 3 /s/MW of beam) and ratio over BLD 50-Sn (A)Baseline designIntermediate solutionHg Jet E E E E E E E E E E E E

EURISOL DS Progress Meeting T2-03, CEA Saclay, France 27 – 28 October, Radioisotope Yields in the U nat C 3 (4) Sn isotopic yields (Ions/cm 3 /s/MW of beam) and ratio over BLD 50-Sn (A)Baseline designIntermediate solutionHg Jet E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E+096.0

EURISOL DS Progress Meeting T2-03, CEA Saclay, France 27 – 28 October, Conceptual Design of the MMW Hg Target Conclusions The Intermediate Solution brings us closer to the ideal performance of a Hg Jet in terms of fission density and relevant isotopic yields, additionally reducing the particle escapes and power densities in Hg The Hg Jet presents important technical issues regarding Hg cooling, radiation damage to the nearby structures and radiation shielding Need to clearly establish the beam requirements (i.e. CW vs. pulsed, beam frequency and beam shape) and fission target configuration

EURISOL DS Progress Meeting T2-03, CEA Saclay, France 27 – 28 October, The End (... or The Beginning)

EURISOL DS Progress Meeting T2-03, CEA Saclay, France 27 – 28 October, times more fissions with U nat C compared to U nat C 3 (proportional to density) With 238 UC less isotropic distribution and fission yield reduced by factor 3 Fission Density Distribution: U nat C vs 238 UC U nat C 238 UC

EURISOL DS Progress Meeting T2-03, CEA Saclay, France 27 – 28 October,  At high masses it is characterized by the presence of three peaks corresponding to (i) the initial target nuclei, (ii) those obtained after evaporation below and (iii) those obtained after acivation above (A+1)  Three very narrow peaks corresponding to the evaporation of light nuclei such as (deuterons, tritons, 3 He and a) ïAn intermediate zone corresponding to nuclei produced by high-energy fissions (symmetric distr.) ï At higher proton energy nuclei from evaporation and multi-fragmentation (ligth nuclei) are more abundant Residual Nuclei Distributions in Hg

EURISOL DS Progress Meeting T2-03, CEA Saclay, France 27 – 28 October,  At high masses it is characterized by the presence of acivation products (Pu239 !!) ==> dominates over fission !!  Three very narrow peaks corresponding to the evaporation of light nuclei such as (deuterons, tritons, 3 He and  ) ==> very few ïAn intermediate zone represented double humped distribution corresponding to nuclei produced by low- energy fissions ï twice as much fission in radial position Radioisotope yields in UC x targets

EURISOL DS Progress Meeting T2-03, CEA Saclay, France 27 – 28 October,  5 times less fissions with U238 overall but…  equal amount of high- energy neutron induced fissions (sym. distribution) Radioisotope yields in UC x targets (2)

EURISOL DS Progress Meeting T2-03, CEA Saclay, France 27 – 28 October, Radioisotope yields in UC x targets (3)  harder neutron spectrum along the beam axis with 2 GeV protons ==> more high-energy neutron induced fissions and few evaporations  no differences radially

EURISOL DS Progress Meeting T2-03, CEA Saclay, France 27 – 28 October, Radioisotope yields in BeO target  aim for 2x He at/s