Liquid targets for positron production - ???

1. Liquid targets for positron production - ??? Jerry Nolen Physics Division, Argonne National Laboratory POSIPOL Workshop Argonne National Laboratory September 6, 2013 This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357.

2. Argonne has a well-established, experienced liquid alkali group based in the Nuclear Engineering Division • This group and the Physics Division have collaborated for several years on the development of liquid lithium technology for use in nuclear physics • Targets in the cm thickness range and in the ~10 micron thinkness range have been developed and tested with high power densities • A summary of these developments will be given in this talk, and some initial consideration of this technology for the LC positron production will be presented • Previous work on this subject has been done with detailed consideration of the various beam time structures options and these studies will not be reviewed here • The point of this talk is to show that appropriate technologies exist to support the necessary engineering studies of this option Liquid metal targets

3. Liquid lithium stripper loop and ion source for beam test Liquid metal targets

4. Views of the proton ion source borrowed from LANL and pictures of the proton beam stopping in a lithium film Liquid metal targets

5. Proton Beam Stopped in Lithium Liquid Film: 200 MW/cm3 Link to thin film beam on target video: http://www.ne.anl.gov/facilities/lal/beam-on/ Liquid metal targets

6. FRIB technical report on the results of the stripper test Liquid metal targets

7. Recent presentation by the Argonne liquid lithium group Thin liquid lithium targets for high power density applications: heavy ion beam strippers and beta beam production Presented at 4th High Power Targetry Workshop May 2nd to May 6th 2011 Hilton Malmö City Claude Reed, Jerry Nolen, Yoichi Momozaki, Jim Specht, Dave Chojnowski, Ron Lanham, Boni Size, and Richard McDaniel Nuclear Engineering Division and Physics Division Liquid metal targets

8. 20 kW beam on Target Thick target and thin target development JInst 4:P04005 (2009) Liquid metal targets

9. Side view 20 kW beam on Target nozzle Li jet beam spot Flow @ 8 m/s Li jet is confirmed stable in vacuum with a U beam equivalent thermal load. Top view nozzle 10 mm 5 mm beam to viewport 20o High Power Test of a Liquid-Lithium Fragmentation Target A 20 kW electron beam produces the same thermal load as a 200 kW U beam on the windowless liquid Li target. Power density is 8 MW/cm3 @ 400 kW beam power at 200 MeV/u.

10. Thermal Design Analysis for Liquid Metal Windowless Targets Y. Momozaki, J. A. Nolen, C. B. Reed, J. Bailey, and P. Strons The Third High-Power Targetry Workshop by Paul Scherrer Institut September10 to 14, 2007 Bad Zurzach, Switzerland

11. 20 kW E-beam-on-Target Test at ANL Background • MCNPX by I.C. Gomes: for RIA, 200-kW uranium beam on Li peak energy deposition = 4 MW/cm3 1MeV, 20 mA, 1mm  e-beam on Li deposited in the first 4 mm • Test Objectives: Using this equivalence, demonstrate that power densities equivalent to a 200kW RIA uranium beam: • Do not disrupt the Li jet flow • Li T (across beam spot) is modest (~ 180º C) • Li vapor pressure remains low • Overall Objective: To show that 4 MW/cm3, deposited in the first 4 mm of the flowing lithium jet, can be handled by the windowless target • }

12. What Experiment Indicates: power density for 1-MeV, 20-kW e-beam • Thermal analysis • 3D Results (using Star CD) 2.5 mm • Estimated maximum temperature in the Li target is 872 K. • No perturbation of the lithium flow was seen even when velocity reduced from 8 m/s to 1 m/s. e-beam 10 mm

13. Thermal Design Analysis for a liquid tin beam dump for uranium beams • Sn beam-dump for AEBL, ANL, USA Beam center at 0.02 m,  = 0.015 m • Estimated maximum temperature in the target is 912 K (Psat ~ 1.810-7 Pa for Sn).

14. Liquid metal pumps are available commercially for a wide variety of metals

15. Liquid lead technology: Pavel Logachev, Budker Adapts truck immersion oil pumps for operation with liquid lead Liquid metal targets

16. Compare Ti and NaK, for example • Using numbers from the LLNL paper: 1 msec macro pulse with 1 kJ per pulse • Assume 50 m/s liquid velocity as we use for the stripper • Specific heat per gram of NaK is 2x Ti, hence at half the velocity, ΔT will be the same • ΔT of NaK within the 1 msec pulse will be ~150K, well within the vapor pressure range • Caution: in the presence of a transverse magnetic field Eddy current forces may deflect the stream; mitigation with a side wall may be implemented • Caution: shock wave effects may disrupt the stream between pulses; this may not be serious since the stream should recover before the next pulse Liquid metal targets

17. Summary • Liquid metal production targets may be useful for positron production • Could be used with either the gamma production or direct electron production • May not be compatible with transverse magnetic field; possible mitigation with a side wall if necessary • Shock waves may disrupt flow between macro-pulses, but recovery probably possible before next pulse Liquid metal targets