Rare Isotope Beam Production with Proton Beam Target

Rare Isotope Beam Production with Proton Beam: Target Consideration Frederique Pellemoine Target Systems Group Leader This material is based upon work supported by the U. S. Department of Energy Office of Science under Cooperative Agreement DE-SC 0000661, the State of Michigan and Michigan State University. Michigan State University designs and establishes FRIB as a DOE Office of Science National User Facility in support of the mission of the Office of Nuclear Physics.

Outline § Rare Isotope Production Mechanics § Rare Isotope Production Techniques • ISOL and In-Flight § ISOL Target Requirements and Material challenges § Examples of ISOL Target Concepts using Proton Beams • Multi-disk target • Molten metal/salt target • 2 step target § Examples of other Rare Isotope Production Target Concepts F. Pellemoine, February 29 2016 Proton Driver Efficieny Workshop, Slide 2

Rare Isotope Production Mechanisms § There a variety of nuclear reaction mechanisms used to add or remove nucleons • Spallation • Fragmentation • Coulomb fission (photo fission) • Nuclear induced fission • Light ion transfer • Fusion-evaporation (cold, hot, incomplete, …) • Fusion-Fission • Deep Inelastic Transfer • Charge Exchange § There is no best method F. Pellemoine, February 29 2016 Proton Driver Efficieny Workshop, Slide 3

Production Mechanisms at High Energy § Fragmentation (FRIB, RIBLL Lanzhou, NSCL, GSI, RIKEN, GANIL, ISOLDE…) • Projectile fragmentation of high energy (>50 Me. V/A) heavy ions • Fragmentation of a target with high energy protons or heavy ions. Could have the fragmentation of the projectile with heavy ion beams. § Fission (HRIBF, ARIEL, ISAC, JYFL, BRIF, ISOLDE…) • Induced fission into roughly equivalent mass products » Medium range mass region • The fissioning nuclei can be the target (HRIBF, ISAC) or the projectile (GSI, NSCL, RIKEN, FAIR, FRIB) § Spallation (ISOLDE, TRIUMF-ISAC, EURISOL, SPES, …) • Products distributions peaks few mass units lighter than target F. Pellemoine, February 29 2016 Proton Driver Efficieny Workshop, Slide 4

Rare Isotope Production Techniques § In-flight method • GSI, RIKEN, NSCL, FRIB, GANIL, ANL, RIBBAS • Provides beams with energy near that of the primary beam » For experiments that use high energy reaction mechanisms » Luminosity (intensity x target thickness) gain of 10, 000 » Individual ions can be identified • Efficient, Fast (100 ns), chemically independent separation • Production target is relatively simple § Isotope Separator On Line (ISOL) method • HRIBF, ISAC, SPIRAL, ISOLDE, SPES, EURIOSOL, CARIBU • Good Beam quality (π mm-mr vs. 30 π mm-mr transverse) • Small beam energy spread for fusion studies • Can use chemistry (or atomic physics) to limit the elements released • High beam intensity leads to 100 x gain in secondary ions • Not adapted for short life time isotope production F. Pellemoine, February 29 2016 Proton Driver Efficieny Workshop, Slide 5

Facility for Rare Isotope Beams in the world TRIUMF-ISAC 500 Me. V – 100 µA EURISOL 1 Ge. V – 100 µA SPES 40 Me. V – 20 µA IGISOL 30 Me. V – 100 µA ISOL@MYRRHA 600 Me. V – 4 m. A ISOLDE 1. 4 Ge. V– 2 µA HIE-ISOLDE 1. 4 Ge. V– 6 µA IBS RISP 70 Me. V- 1 m. A SARAF 40 Me. V – 5 m. A In-flight production ISOL production using proton beam (In operation – upgrade or construction – project) F. Pellemoine, February 29 2016 Proton Driver Efficieny Workshop, Slide 6

ISOL Method Target Projectile Source Spectrometer Production Diffusion Effusion Ionisation 3. 6 1012 pps 36 Ar 18+ 590 pps 32 Ar 7+ Selection Post Accelerator Acceleration 176 pps 32 Ar 7+ § Determining the correct target material, target geometry and ion source for a particular beam requires careful development and study Path of an atom travelling out of a foil target to the ion source (RIBO code, (Santana-Leitner, 2005)) F. Pellemoine, February 29 2016 Proton Driver Efficieny Workshop, Slide 7

Challenges for RIB Production with ISOL Method Production Diffusion Effusion Ionisation Beam stopped in the target: manage power deposition and cool down the target. Target container has to dissipate the power from target to an external power sink Need to keep the target material uniformly at high temperature: need to heat the target Target material sintering leads to large grain formation, not good for fast diffusion release Depends on RIB, need of high surface temperature of the transfer line or cold temperature pipe (for a good selectivity) Target material evaporation lead to high pressure, not good for ion source Maximize the range in the target Multi disk target (but increase Compact target size) Need to minimize distance target-ion source Refractory metal, carbide, oxides Oxide has usually lower operating temperature Container material needs to be compatible with target material Target material evaporation lead to high pressure, not good for ion source If water cooling, risk of sudden oxidation of target at high temperature when crack formation F. Pellemoine, February 29 2016 Proton Driver Efficieny Workshop, Slide 8

ISOL Target Requirements to Maximize the Production § Criteria for target material • Production rate » Large cross section • Physical properties » Low density » Diffusion coefficient » Highest possible operating temperature » High emissivity and thermal conductivity » High permeability to the effusion of the isotopes produced • Chemical properties § Target geometry • Multi-disk target » Target temperature must be uniform over the whole target » Thin disks help for diffusion • Molten metal/salt target » Higher density but need to manage higher power density in the target » Fast evacuation of irradiated molten metal (t~100 ms) to minimize decay losses of short lived Isotopes • 2 step target F. Pellemoine, February 29 2016 Proton Driver Efficieny Workshop, Slide 9

ISOL Target Limited lifetime § Thermo-mechanical challenge • High power density High thermo-mechanical stress • High temperature Creep and material evaporation/sublimation/sintering • Pulsed beams / rotating targets / rotating beams Fatigue, thermal shocks and shock waves in material • Molten metal/salt target Corrosion and Cavitations § Radiation damage challenge • Irradiations induce changes of physical properties and decrease target performance » Thermo-mechanical properties thermal conductivity, tensile and flexural strength » Electronic properties Resistivity » Structural properties microstructure and dimensional changes, swelling » Radiation enhance creep and corrosion § Need to have reliable system and deliver a constant intensity over time F. Pellemoine, February 29 2016 Proton Driver Efficieny Workshop, Slide 10

ISOL Target Improving lifetime § Development of new material is necessary to sustain increasing power deposition in target and radiation damage Si. C § Very few target materials can sustain high power deposition § Best target material are: • Refractory metals (Ta, Nb, Mo, W) • Carbides • Oxides, have lower operating temperature § RIB production demands for other type of target material • Na, Mg and Al isotopes production for nuclear astrophysics experiments demand high proton intensity on carbide target material, Si. C • U target > 50% of the RI beam time. § Need to improve the target material properties NIMB 317 (2013) 385 UCx • Example : overall thermal conductivity » Composite target http: //www. lnl. infn. it/~spes_target F. Pellemoine, February 29 2016 Proton Driver Efficieny Workshop, Slide 11

Target concepts for RIB Solid Multi-disk Target Concept § TRIUMF-ISAC (Si. C, Ti. C, Zr. C, UC, Ta, Nb, Ni. O, Nb 5 Si 3, Al 2 O 3) § ISOLDE (UC 2, Si. C, Pb, Ta, Ti, Mg. O, Ca. O, . . . ) § HIE-ISOLDE (UC 2, Si. C, Pb, Ta, Ti, Mg. O, Ca. O, . . . ) § SPES (Ucx) § IBS-RISP (UC 2) F. Pellemoine, February 29 2016 Proton Driver Efficieny Workshop, Slide 12

Solid Multi-disk Target Design Study and Validation § Target concept validated with prototype and off-line test http: //www. lnl. infn. it/~spes_target/ENG/the-target-1. php F. Pellemoine, February 29 2016 Proton Driver Efficieny Workshop, Slide 13

Target concepts for RIB Liquid Metal target Concept § Direct target using proton beam • ISOLDE » Slow diffusion process significant decay losses for short-lived isotopes (~ ms) » Difficult heat management when increasing beam power • EURISOL » LIEBE Target: Liquid Eutectic Lead Bismuth Loop Target for EURISOL • Improved diffusion efficiency (LBE spread in a shower of small droplets) • Loop-type design with HEX good heat management • Capability to operate at high beam-powers (~ 100 k. W) » Requirements • Fast evacuation of irradiated liquid metal to minimize decay losses of short lived isotopes • Small droplets (r~100 µm) to reduce diffusion length • Sufficient fall time to increase overall diffusion efficiency • ISOL@MIRRHA F. Pellemoine, February 29 2016 Proton Driver Efficieny Workshop, Slide 14

Liquid metal Target Design Study and Validation § LIEBE Target: Liquid Eutectic Lead Bismuth Loop Target for EURISOL § Target concept optimized through CFX simulation and will be tested with prototype at CERN-ISOLDE D. Houngbo et al. , “Development of a liquid Pb. Bi target for high-power ISOL facilities”, NIMB 2016, available on line 4 Feb 2016, doi: 10. 1016/j. nimb. 2016. 01. 021 Release by diffusion is maximized for spherical shape (droplets) of 100 μm radius F. Pellemoine, February 29 2016 Proton Driver Efficieny Workshop, Slide 15

Target concepts for RIB Increasing RIB Intensity § Two step target using neutron induced fission • Less power deposition inside the production target material when using neutron as secondary particles • Separate the cooling issues of the converter and the production target » Production target can operate at its optimum temperature • RIB production with indirect ISOL target is limited mainly to fission products • Key experiments (fundamental symmetries, EDM, …) are requesting RIB species that are not produced using fission mechanism! Need direct target production! • 2 -step targets provide a path to MW targets § Types of “converter” target are envisaged: • Rotating wheel target • Stationary cooled target » ISOLDE • Liquid metal target (Li, LBE, Hg, …) » SARAF • LILIT target » EURISOL F. Pellemoine, February 29 2016 Proton Driver Efficieny Workshop, Slide 16

Two Step Target using Neutron Induced Fission § Advanced proton-to-neutron converter at ISOLDE-CERN A. Gottberg et al. , Experimental tests of an advanced proton-to-neutron converter at ISOLDE-CERN, NIMB 336 (2014) 143 -148 Fig. 7. Efficiency ε=εrel·εo for Rb isotopes as a function of the isotope half-lives. The experimental release parameters used in the approximation are: αα = 0. 471, λfλf = 1. 82 s-1, λs = 0. 140 s− 1 and λrλr = 57. 8 s− 1. F. Pellemoine, February 29 2016 Proton Driver Efficieny Workshop, Slide 17

Proton Beams are not the Unique Beams to Produce RIB (1) § From heavy ion beams • Used In-Flight or ISOL methods and direct target • Used fragmentation and fission processes of both projectile and target • GANIL-SPIRAL, NSCL-FRIB, GSI-FAIR, RIKEN-RIPS § Types of “direct” target are developed: • Fixed conical target @ GANIL (1. 5 k. W) • Single slice rotating target @ GSI (7 k. W) and RIKEN (22 k. W) • Multi slice rotating target @ FRIB (100 k. W) watercooled disk double-piped shaft SPIRAL Air-press. Box Big-RIPS Target vacuum chamber Super FRS F. Pellemoine, February 29 2016 Proton Driver Efficieny Workshop, Slide 18

Proton Beams are not the Unique Beams to Produce RIB (2) § Multi slice rotating graphite target @ FRIB • High power capability » Up to 100 k. W in a ~ 0. 3 - 8 g/cm² » ~ 20 - 60 MW/cm³ Shield block Motor Target disk / heat exchanger module • High temperature » Maximum temperature at 1900 ºC » High thermo-mechanical stress • Rotating target: 5000 rpm » Temperature variation • Fatigue • Stress wave through the target • Modal analyses and vibration studies Multi-slice target / heat exchanger F. Pellemoine, February 29 2016 Proton Driver Efficieny Workshop, Slide 19

Proton Beams are not the Unique Beams to Produce RIB (3) § From electron using photofission • ARIEL (Advanced Rare Isotope Laboratory) • 2 step targets: production by bremsstrahlung-induced fission of a uranium target § Rotating water-cooled wheel, Pb and Ta converter and UC 2/C target • 274 k. W in the converter, 120 k. W in HS • 66 k. W in the target. F. Pellemoine, February 29 2016 Proton Driver Efficieny Workshop, Slide 20

In-Target Production Yield Example with 132 Sn § Studies of neutron-rich nuclei beyond the doubly magic 132 Sn are of key importance to investigate the single particle structure above the N=82 shell closure and find out how the effective interaction between valence nucleons behaves far from stability TRIUMFISAC CERNISOLDE IBS-RISP LNL-SPES EURISOL ARIEL FRIB p p p e- U Energy [Me. V] 500 1000 -1400 70 40 1000 50 47600 Intensity [µA] 100 2. 5 1, 000 200 10, 000 5, 000 Power in target [k. W] 50 3 70 8 100 50 90 5 e 10 to 1. 5 e 11 for 10 μA ~1 e 10 (6 e 8 delivered) ~2 e 9 1. 6 e 9 3 e 11 @ 0. 5 Ge. V 3. 9 e 9 1. 4 e 7* 5 e 9 to 1. 5 e 10 4 e 9 2 e 6 8 e 6 3 e 9 3. 9 e 5 3 e 3 * In-target Production yield 132 Sn [pps] Normalized in target production yield [pps/µA] * Already accelerated! F. Pellemoine, February 29 2016 Proton Driver Efficieny Workshop, Slide 21

Summary § Each facilities have their own specificities and are complementary § Contrary to other high power target, the ISOL targets have to operate at the optimum temperature to speed the release of isotopes • Temperature must be uniform over the whole target, • Target is couple to the ion source, must avoid pressure overload, • Cold transfer tube for volatile species only help. § New techniques were developed to reach high power beam on ISOL target • Target material capable of operating at very high power deposition § Indirect ISOL target method allows to separate the cooling problem of the converter and the ISOL target • Can reach higher power using secondary neutrons » But radioactive ion beams limited to fission products § New target concepts for high power direct ISOL are being proposed • Liquid metal, LBE, salt • Powder flow § In-flight method and other primary beams could provide high intensity RIB F. Pellemoine, February 29 2016 Proton Driver Efficieny Workshop, Slide 22

Thank you for your attention F. Pellemoine, February 29 2016 Proton Driver Efficieny Workshop, Slide 23

Backup Slides F. Pellemoine, February 29 2016 Proton Driver Efficieny Workshop, Slide 24

F. Pellemoine, February 29 2016 Proton Driver Efficieny Workshop, Slide 25

High Power Target Technology Rotating single-slice targets FRIB - 400 k. W Rotating multi-slice targets FRIB PSI Static targets Liquid Li targets RIKEN F. Pellemoine, February 29 2016 Proton Driver Efficieny Workshop, Slide 26

Target concepts for RIB New proposal facilities § EURISOL • Final Report of the EURISOL Design Study (2005 -2009) A DESIGN STUDY FOR A EUROPEAN ISOTOPESEPARATION-ON-LINE RADIOACTIVE ION BEAM FACILITY November 2009, Edited by John C. Cornell Published by GANIL B. P. 55027, 14076 Caen cedex 5, France September, 2009 F. Pellemoine, February 29 2016 Proton Driver Efficieny Workshop, Slide 27

Target concepts for RIB New proposal facilities § ISOL@MIRRHA • MYRRHA: Multi-purpose Hybrid Reactor is conceive as an accelerator driven system (ADS). Use fast neutron spectrum from spallation • Accelerator » Superconducting proton LINAC » High power LINAC: 600 Me. V: 4 m. A: CW » Ideal for isotopes production on-line • To verify the sub-criticality of the reactor, short proton beam interruption (200 μS). » ISOL@MYRRHA can utilize 100 to 200 μA proton beam in ~ CW » Possible extension of the ISOL@MYRRHA proton beam energy to 1. 0 Ge. V F. Pellemoine, February 29 2016 Proton Driver Efficieny Workshop, Slide 28

Target concepts for RIB IBS-RISP F. Pellemoine, February 29 2016 Proton Driver Efficieny Workshop, Slide 29