Rare Isotope Accelerator RIA Opportunities & Challenges. Richard C. York October 2004 MIT

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1 Rare Isotope Accelerator RIA Opportunities & Challenges Richard C. York October 2004 MIT 1

2 RIA Status Strong Nuclear Science community support Nuclear Science Advisory Committee Long Range Plan (April 2002) RIA highest priority new facility The Rare Isotope Accelerator (RIA) is our highest priority for major new construction Tied for third position for near term priorities in DOE 20-year plan (November 2003) RIA CD-0 done early 2004 RIA RFP expected?? 2

3 DOE 20-Year Facilities Outlook Near-Term Priorities 1. ITER 2. UltraScale Scientific Computing Capability 3. Tie for 3 Joint Dark Energy Mission Linac Coherent Light Source Protein Production & Tags Rare Isotope Accelerator (RIA) 7. Tie for 7 Characterization & Imaging of Molecular Machines 8. CEBAF 12 GeV Upgrade Energy Sciences Network (ESnet) Upgrade National Energy Research Scientific Computing Center Upgrade 11. Transmission Electron Achromatic Microscope 12. BTeV 3

4 RIA Benefits Important benefits for basic & applied science Study properties of a large number of isotopes that heretofore only existed in cosmos Quantitative information for theories of stellar evolution & formation of elements in cosmos Support space-based astronomical observations by providing quantitative comparisons with theoretical predictions of stellar evolution Experimental data to refine theories for predicting properties of nuclei with unusual neutron-to-proton ratios 4

5 RIA Benefits - cont d Support stockpile stewardship Only way to obtain important reaction cross sections on unstable isotopes & to improve theoretical models Improved diagnostic tools via isotopic analysis of materials from underground nuclear tests Produce almost any isotope for radio-medical research Materials Science & other applications Implantation for wear & corrosion studies Space radiation effect studies Material modifications doping & annealing techniques 5

6 RIA Scale RIA project cost (in FY2001 dollars) TEC = ~$695 M ($550 M w/o contingency) TPC (TEC + Pre-ops, etc) = ~885 M$ over ~7-8 years Operations - ~80 M$/year similar to JLab 6

7 Production of Rare Isotopes at Rest Target Fragmentation 1. Random removal of protons and neutrons from heavy target nuclei by energetic light projectiles (preequilibrium and equilibrium emissions). 2. Extraction of rare isotopes by diffusion; ionization and acceleration: beams of high quality. 7

8 Radioactive ion beam Classical ISOL Facility Concept Excellent beam quality and low beam energies are possible Limited to longer lifetimes (τ > 1s) Isotope extraction and ionization efficiency depend on chemical properties of element: difficult, element-specific development paths The most neutron-rich isotopes will have too low intensities and too short lifetimes to be suitable for re-acceleration Transfer tube Ion source Production accelerator Thick, hot target Production beam Isotope / isobar separator Postaccelerator Experiment 8

9 Production of Rare Isotopes in Flight Projectile Fragmentation 1. Random removal of protons and neutrons from heavy projectile in peripheral collisions. hot participant zone projectile fragment projectile target 2. Cooling by evaporation. radioactive beam projectile fragment 9

10 Schematic of a Projectile Fragmentation Facility High-energy beams (E/A > 50 MeV) of modest beam quality Physical method of separation, no chemistry Suitable for short-lived isotopes (τ > 10-6 s) Low-energy beams are difficult Solution stop in gas cell & reaccelerate Heavy ion accelerator Thin production target Fragment separator Radioactive ion beam Experiment 10

11 Example Fragment Separation Technique (NSCL) 100 pna 86Kr 5 kw Beam power 8 msr p = 5% Wedge location D = 5 cm/% R = 2500 p/ p 65% of the 78Ni is transmitted 11

12 The Rare Isotope Accelerator (RIA) Concept Combines advantages of projectile & target fragmentation techniques Use all tools developed for rare isotope research worldwide 12

13 General Comments Technical Risks No Show Stoppers but significant challenges ~5 years - significant efforts on the driver linac - Optimization strategies & detailed considerations Relatively less activity on the target and experimental areas Recently these arenas have seen dramatic increase in focus Significant challenges and issues recognized 13

14 RIA Layout Driver linac straight or folded (shown) decision based on optimization 14

15 RIA at MSU Over 5000 acre campus potential sites within 5 minutes of classroom Next generation scientists & multi-discipline synergies North 15

16 Driver Linac Sample Beam List Design goal - Constant beam power 100 kw minimum 400 kw if ion source capable Multiple charge state acceleration for >Xe Ion A Z Final Energy (MeV/u) H He D O Ar Kr Xe U

17 Comparison of Rare Isotope Intensities Approximate Intensity Gains of RIA over NSCL proton number neutron number possible location of neutron dripline stable isotope 10: comparable ,000 larger than 10,000 17

18 Driver Linac Front End 18

19 Superconducting Driver Linac Design driven by 400 MeV/nucleon uranium 28+ & 29+ U injected into SC linac at 292 kev/u Segment I Accelerated to ~12 MeV/u & stripped Segment II 5 charge states (73±2) accelerated to ~90 MeV/u Segment III Stripped and 3 charge states (88 ±1) accelerated to 400 MeV/u I II III Fold point 19

20 Superconducting Structures Legnaro MSU Tested 2003 Exceeded Specs. MSU ß opt = MHz MSU/JLAB ß opt = MHz SNS ß opt = MHz SNS ß opt = MHz ß opt = MHz ß opt = MHz 20

21 Superconducting Segments 6 cavity types Cavity f T Linac # Of βopt Type (MHz) (K) Segment Cavities λ/ I 18 λ/ I 104 λ/ II 208 Ellip III 68 Ellip III 64 Ellip III 32 Total

22 Driver Linac Stripping Chicanes High symmetry good higher-order corrections Positioned to support longitudinal matching at frequency changes 1 st Stripping Chicane X Entrance Y Z X Exit Y Z 22

23 Transit Time Factors & Energy Gain Stripping locations U H 23

24 NSCL SRF Facility Layout 24

25 NSCL SRF Chemistry Facility BCP Pumping System Temperature <15 C Heat Exchanger 5 kw Filtration 4 microns Speed 8 gpm 25

26 NSCL SRF R&D Facility 26

27 Isolated vacuum Segments I & II Cryostats Superconducting solenoid focusing 27

28 Low-β Cryomodule Prototype 0.6 T Quadrupole QWR, ß opt = T Solenoid HWR, ß opt =

29 Segment III Cryostats Two-cavity β=0.49 prototype Tested Spring

30 βopt=0.49 elements Tuner He Vessel Power Coupler 30

31 β= 0.49 Prototype Systems Test Support Link Top Plate He Supply Ti Rails He Return Tuner Power Coupler 31

32 Natural Modes/Mechanical Resonances 42 Hz 72 Hz 121 Hz 142 Hz 32

33 Cavity and microphonics circuit Q ext, fixed 1x10 7 Q ext, transformer 10 5 to 4x

34 RIA Layout - BSY Beam Switch Yard 34

35 Time Driver Linac Switch Yard Baseline provide two beams (of same isotope) to two targets simultaneously (µ-bunch) Voltage

36 RIA Layout - Target Area Target Area 36

37 ISOL Target Area Concepts 400 kw beam power Many R&D Issues ~10x existing designs - major technical challenge for ISOL targets Infrastructure proposed suitable for ultimate 400 kw Three (possibly staged) ISOL target stations proposed Redundancy & beam development & R&D to higher powers target stations with pre-separator and focal-plane switchyard to stopped beam area high-resolution separators from gas stopping station < 400 kw primary beam ECR beam transport matrix to postaccelerator 37

38 ISOL Target Layout To high resolution separators Pre-separator Target Plug Hot cell Crane Service Transfer area Plug Storage Target service docks Tele manipulator stations Remote control room 38

39 ISOL Target Station to prevacuum line vacuum pumps Isolated HG feedthroughs HV - electrical feedthroughs to HV platforms ` 1 m beam lines Laser beams service channels for Hg, gas, water, electric power and instrimentation vacuum duct focal plane beam switchyard electrical wires mounted on insulators ` Hg loop pipes mounted on insulators Target ion source unit Hg spill tank Slit system + beam diagnostics + optics ` pre-separator dipole magnet 39 Ion optics inflatable seals

40 ISOL Hot Cell & Service Gallery Target area service gallery Services Access plugs Remote Control Room Target shielding 40

41 Facility Classification Category 1 Potential for significant off-site consequences Category 2 Potential for significant on-site consequences Category 3 Potential for localized consequences 1.E+09 Spallation of UC2 Target 1836 MeV 3He, 100 kw, Stopping Target 7-Day Irradiation, 1-Day Cool LAHET+MCNP+ORIHET Cat 2 Cat 3 1.E+08 1.E+07 1.E+06 Activity (Ci) 1.E+05 1.E+04 1.E+03 1.E+02 Calculation DOE Cat. 2 Thresh DOE Cat. 3 Thresh 1.E+01 1.E+00 1.E-01 1.E Fragment Mass (A) 41

42 Fragmentation Production Area Targets R&D challenge High power density - ~ 500 kw/cm 3 (400 kw primary beam) Small spot size reduce geometric aberrations ~20% of beam power lost in target Heavy ions have high de/dx Pre-separator concept Begin to isolate downstream system from very high radiation environment High performance & radiation resistant magnets required R&D challenge 42

43 Pre-Separator Dipole Quad-Triplet NSCL Wedge Isotope Slits Beam Target Beam Dump 43

44 PHITS 1.69 Neutron Heating Calculation 400 kw beam Iron heat load = 9 kw Coil heat load = 130 W Beam Coil dose ~ 1 MGy/year Organic dose ~200 MGy/year 44

45 RIA Layout Low Energy Area Low Energy Area 45

46 Low-energy Experimental Area Important to make design compatible with very different types of targets Mass separators with beam cooling may be better & cheaper R&D Required Post accelerator ( 10 MeV/u for A up to 240, 20 MeV/u for A<60) 46

47 RIA Layout High Energy Area High Energy Area 47

48 Fragment Separators High acceptance design feeding helium gas stopping station 10 T-m, 12% momentum acceptance, 10 msr High resolution design feeding fast beam area 10 T-m, 6% momentum acceptance, 8 msr Similar to NSCL design Pre-separator segment Remove primary beam & most of unwanted fragments R&D Challenge Optical design with radiation resistant magnets and beam interception elements 48

49 Fragmentation Separation Area Layout Gas Cell 49

50 Gas Stopping Station Layout Provides beam from gas stopping to low-energy area Allows use of fragment separator to send beam to high-energy area Good R&D progress made with NSCL gas cell Shown ~20-50% incident ion implanted Shown range-compression technique workable Outstanding R&D questions remain What is system efficiency? What is rate limitation? 50

51 Gas Stopping at the NSCL Beam Gas cell RFQ 1 RFQ 2 RFQ 3 Acceleration optics To from A1900 buncher Degraders Entrance window Nozzle Supersonic gas jet Skimmer Orifice Pressure (He): ~1 bar ~ 0.1 mbar ~10-3 mbar < 10-6 mbar Stopping/extractions of radioactive isotopes works Systematic studies of intensity limits Optimized ion guiding schemes and geometries Substantial R&D still required 51

52 Gas Stopping Efficiency Total efficiency decreases with implantation rate P/P 0.5 %, gas_cell_1.2_50 Known implantation rate of ions [ 38 Ca]. Measured stopping fractions: Glass thickness (µm) 18 k pps 6 k pps 2 k pps 0.4 k pps 0.04 k pps gas-equivalent stopping /

53 High Energy Experimental Area 53

54 Summary Fully general RIA facility accommodating baseline and future capabilities has been developed Driver linac with beam transport Relatively detailed design Beam transport flexibility increase remains a challenge Target and experimental areas General designs defined & issues identified Provides for large range of possibilities for future capabilities R&D priorities identified 54