1. RIA Summer School 2006 Exotic Beam Production and Facilities II Brad Sherrill, Michigan State University Lecture I The Rare Isotope Accelerator Concept Some history and background The status of exotic beam plans in the USA Lecture II Methods of exotic beam production Production mechanisms (e.g. fragmentation) Current world situation for exotic beams Brad Sherrill, Michigan State University Lecture I The Rare Isotope Accelerator Concept Some history and background The status of exotic beam plans in the USA Lecture II Methods of exotic beam production Production mechanisms (e.g. fragmentation) Current world situation for exotic beams

2. RIA Summer School 2006 Production Mechanisms In-flight Separation ISOL – Isotope Separation On-Line Neutron induced fission (2-step target) In-flight Separation ISOL – Isotope Separation On-Line Neutron induced fission (2-step target) Post Acceleration Driver Accelerator Fragment Separator beam Gas cell catcher/ion source Driver Target/Ion Source Neutrons Post Acceleration Beams used without stopping

3. RIA Summer School 2006 Good Beam quality (  mm-mr vs. 30  mm-mr transverse) Small beam energy spread for fusion studies Can use chemistry (or atomic physics) to limit the elements released 2-step targets provide a path to MW targets High beam intensity leads to 100x gain in secondary ions Good Beam quality (  mm-mr vs. 30  mm-mr transverse) Small beam energy spread for fusion studies Can use chemistry (or atomic physics) to limit the elements released 2-step targets provide a path to MW targets High beam intensity leads to 100x gain in secondary ions Advantages/Disadvantages of ISOL/In-Flight 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 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 In-flight: GSI RIKEN NSCL GANIL ISOL: HRIBF ISAC SPIRAL ISOLDE 400kW protons at 1 GeV is 2.4x10 15 protons/s

4. RIA Summer School 2006 (p,n) (p,nn) etc. o E p < 50 MeV o Used for the production of medical isotopes. o Selective, large production cross sections (100 mb), and intense (500  A) primary beams. o Used at HRIBF(ISOL), LLN (ISOL), ANL (in-flight) and Notre Dame (in-flight), Texas A&M (in-flight) Fusion o Low energy 5-15 MeV/A and “thin” targets o Selective with fairly large production cross sections. o Used at ANL(in-flight), JYFL (Jyväskylä) (p,n) (p,nn) etc. o E p < 50 MeV o Used for the production of medical isotopes. o Selective, large production cross sections (100 mb), and intense (500  A) primary beams. o Used at HRIBF(ISOL), LLN (ISOL), ANL (in-flight) and Notre Dame (in-flight), Texas A&M (in-flight) Fusion o Low energy 5-15 MeV/A and “thin” targets o Selective with fairly large production cross sections. o Used at ANL(in-flight), JYFL (Jyväskylä) Production Methods – Low Energy

5. RIA Summer School 2006 High, specific production cross sections Example: 58 Ni( 3 He,n) 60 Zn, E He = 100 MeV o Production cross section from ALICE: 100  b o 4 g/cm 2 target o Yield of 60 Zn is 3x10 7 /p  A (LBL 88-inch has 10 p  A of 3 He) o Heavier beams can have larger cross sections, but require thinner targets. High, specific production cross sections Example: 58 Ni( 3 He,n) 60 Zn, E He = 100 MeV o Production cross section from ALICE: 100  b o 4 g/cm 2 target o Yield of 60 Zn is 3x10 7 /p  A (LBL 88-inch has 10 p  A of 3 He) o Heavier beams can have larger cross sections, but require thinner targets. Example of production by fusion

6. RIA Summer School 2006 Transfer reactions o Significant cross section between 10 - 50 MeV/A (this energy range implies thin targets, mg/cm 2 ) o High production of nuclei near stability. o Multi-nucleon reactions can be used to produce rare or more neutron rich nuclei, e.g. GSI mass separator had a program to study neutron rich f-p shell nuclei using neutron transfer. Deeply inelastic reactions o Deep inelastic - much of the KE of the beam is deposited in the target. o Was used to first produce many of the light neutron rich nuclei o Is used to study neutron rich nuclei since the products are “cooler” and fewer neutrons are evaporated than in fusion reactions. Transfer reactions o Significant cross section between 10 - 50 MeV/A (this energy range implies thin targets, mg/cm 2 ) o High production of nuclei near stability. o Multi-nucleon reactions can be used to produce rare or more neutron rich nuclei, e.g. GSI mass separator had a program to study neutron rich f-p shell nuclei using neutron transfer. Deeply inelastic reactions o Deep inelastic - much of the KE of the beam is deposited in the target. o Was used to first produce many of the light neutron rich nuclei o Is used to study neutron rich nuclei since the products are “cooler” and fewer neutrons are evaporated than in fusion reactions. Low Energy - Continued

7. RIA Summer School 2006 Fragmentation (NSCL, GSI, RIKEN, GANIL) o Projectile fragmentation of high energy (>50 MeV/A) heavy ions o Target fragmentation of a target with high energy protons or light HIs. In the heavy ion reaction mechanism community these are called intermediate mass fragments. Spallation (ISOLDE, TRIUMF-ISAC) o Name comes from spalling or cracking-off of target pieces. o One of the major ISOLDE mechanisms, e.g. 11 Li made from spallation of Uranium. Fission (technically not only high energy) o There is a variety of ways to induce fission (photons, protons, neutrons (thermal, low, high energy) o The fissioning nuclei can be the target (HRIBF) or the beam (GSI/MSU/RIKEN). Coulomb Breakup o At beam velocities of 1 GeV/n the equivalent photon flux as an ion passes a target is so high the GDR excitation cross section is many barns. Fragmentation (NSCL, GSI, RIKEN, GANIL) o Projectile fragmentation of high energy (>50 MeV/A) heavy ions o Target fragmentation of a target with high energy protons or light HIs. In the heavy ion reaction mechanism community these are called intermediate mass fragments. Spallation (ISOLDE, TRIUMF-ISAC) o Name comes from spalling or cracking-off of target pieces. o One of the major ISOLDE mechanisms, e.g. 11 Li made from spallation of Uranium. Fission (technically not only high energy) o There is a variety of ways to induce fission (photons, protons, neutrons (thermal, low, high energy) o The fissioning nuclei can be the target (HRIBF) or the beam (GSI/MSU/RIKEN). Coulomb Breakup o At beam velocities of 1 GeV/n the equivalent photon flux as an ion passes a target is so high the GDR excitation cross section is many barns. Production Mechanisms – High Energy

8. RIA Summer School 2006 Fission Cross Sections Low energy fission can lead to higher yields for certain nuclides. This is the basis of the electron driver upgrade of the HRIBF. Low energy fission can lead to higher yields for certain nuclides. This is the basis of the electron driver upgrade of the HRIBF.

9. RIA Summer School 2006 HRIBF eBeam Upgrade Bremsstrahlung from the electron beam induces photo- fission in a uranium carbide target system with a thickness of ~35 g/cm 2 A 50 kW, 100 MeV electron beam incident on such a target would generate a total uranium fission rate 25 times greater than a 20 μA, 50 MeV proton beam. In addition, the yield of neutron-rich species is shifted much farther from stability than for proton induced fission. This would result in a factor of 1,000 to 10,000 increase in beam intensities at HRIBF Bremsstrahlung from the electron beam induces photo- fission in a uranium carbide target system with a thickness of ~35 g/cm 2 A 50 kW, 100 MeV electron beam incident on such a target would generate a total uranium fission rate 25 times greater than a 20 μA, 50 MeV proton beam. In addition, the yield of neutron-rich species is shifted much farther from stability than for proton induced fission. This would result in a factor of 1,000 to 10,000 increase in beam intensities at HRIBF http://www.phy.ornl.gov/hribf/initiatives/electrons/

10. RIA Summer School 2006 Projectile Fragment Spallation Product Intermediate Mass Fragment/ Target Fragment Terminology for High Energy Reactions The fragment could emit nucleons (fragmentation) and/or fission See the lectures of D Bazin ABRABLA - A. R. Junghans, K.-H. Schmidt et al, Nucl. Phys. A 629 (1998) 635

11. RIA Summer School 2006 Overview of the In-Flight Technique Wedge location D = 5 cm/% R = 2500 p/  p 100 pnA 86 Kr 5 kW Beam power 8 msr  p = 5% Example: The NSCL Coupled Cyclotron Facility 65% of the 78 Ni is transmitted Morrissey and Sherrill: Euroschool Lectures

12. RIA Summer School 2006 Multiple stages of separation H. Geissel et al. NIM B Higher energy provides cleaner separation.

13. RIA Summer School 2006 LISE++ Simulation Code The code operates under Windows and provides a highly user-friendly interface. It can be downloaded freely from the following internet address: http://www.nscl.msu.edu/lise O. Tarasov et al.

14. RIA Summer School 2006 Facility Specifications 78 Ni from 86 Kr No secondary reactions Tony Nettleton

15. RIA Summer School 2006 Fragmentation at 400MeV/u Angles ≤ ± 20 mrad Momentum ± 3 - 8 % Relatively ‘easy’ due to small phase space Momentum distrib. 100 Sn 200 W M. Hausmann, T. Nettleton

16. RIA Summer School 2006 In-Flight Fission at 400 MeV/u Angles ± 40 - 60 mrad Rigidity ± 6 - 10 % Plus correlations due to fission kinematics More challenging due to larger phase space 132 Sn 76 Ni M. Hausmann, T. Nettleton

17. RIA Summer School 2006 NSCL Coupled Cyclotron Project Experimental Areas Cyclotrons – up to  MeV/u ECR Operational – will study N=82 nuclei and nuclei along the neutron drip line up to mass 30.

18. RIA Summer School 2006 Particle Identification

19. RIA Summer School 2006 Beams Produced with CCF/A1900

20. RIA Summer School 2006 GSI Current RNB Facility Production of 100 Sn and 78 Ni Hundreds of new masses and isotopes, …

21. RIA Summer School 2006 Cold Fragmentation Studied at GSI 197 Au + Be at 950 A MeV J. Benlliure, K.-H. Schmidt, et al. Nuclear Physics A 660 (1999) 87 5

22. RIA Summer School 2006 The GSI FAIR Facility Layout from J. Nolen ANL

23. RIA Summer School 2006 RIKEN Radioactive Ion Beam Factory from J. Nolen ANL

24. RIA Summer School 2006 RIKEN RIBF Heavy-ion accelerator system An ion source current of 32 p-μamps is required to reach uranium beam goal.

25. RIA Summer School 2006 Targets and Production Mechanisms from J. Nolen ANL

26. RIA Summer School 2006 I =  I b T useable  diff  des  eff  is_eff  accel_eff H. Ravn   - production cross section ·I b - beam intensity ·T useable - usable target thickness   diff – diffusion efficiency   des – desorption efficiency   eff – effusion efficiency   is_eff - ionization efficiency   accel_eff - acceleration efficiency   - production cross section ·I b - beam intensity ·T useable - usable target thickness   diff – diffusion efficiency   des – desorption efficiency   eff – effusion efficiency   is_eff - ionization efficiency   accel_eff - acceleration efficiency Production is only one part of the equation target

27. RIA Summer School 2006 ISOLDE http://isolde.web.cern.ch/ISOLDE/ CERN PSB 1 GeV protons 2 mA Intensities up to 10 11 pps CERN PSB 1 GeV protons 2 mA Intensities up to 10 11 pps Accelerate to 3.0 MeV/u

28. RIA Summer School 2006 SPIRAL at GANIL http://www.ganil.fr/spiral/index.html

29. RIA Summer School 2006 GANIL SPIRAL-2 Completion ~2011 Completion ~2011

30. RIA Summer School 2006 ISAC Radioactive Beam Facility - ISOL Beams are produced by 500 MeV protons from TRIUMF cyclotron. 2x10 9 22 Na/s ISAC-II underway

31. RIA Summer School 2006 ISAC-2 overview ISAC has a fixed 500- MeV proton beam driver with 50-kW power.

32. RIA Summer School 2006 Texas A&M Upgrade Project http://cyclotron.tamu.edu/ Radioactive beams to 50 MeV/u Difficult isotopes from the ion-guide Radioactive beams to 50 MeV/u Difficult isotopes from the ion-guide

33. RIA Summer School 2006 EURISOL 5 MW Proton LINAC http://www.ganil.fr/eurisol/index.html

34. RIA Summer School 2006 Overview of the RIA Concept

35. RIA Summer School 2006 A combination of forces working together is required to obtain Fast extraction times over the full volume High efficiency over the full volume Tolerance to high intensity A combination of forces working together is required to obtain Fast extraction times over the full volume High efficiency over the full volume Tolerance to high intensity Forces in gas catcher system from J. Nolen ANL

36. RIA Summer School 2006 Momentum Compensation Diagram: H. Weick et al., NIM B 164-165 (2000) 168 FWHM = 32 atm-m 4 He FWHM = 0.93 atm-m 4 He Above: Range compression of 350 Mev/u 130 Cd produced from 500 MeV/u 136 Xe (MOCADI simulation) 130 Cd Range FWHM (atm-m) Resolving Power 350 MeV/u 130 Cd range width M. Amthor

37. RIA Summer School 2006 beam from A1900 9.4 T Penning trap system mass measurements Many systematic studies: L. Weissman et al., NIM A522 (2004) 212, NIM A531 (2004) 416, Nucl. Phys. A746 (2004) 655c, NIM A540 (2005) 245. T 1/2 = 440 ms R = 2  10 6  m/m < 10 -8 First nuclear physics experiment with thermalized beams from fast beam fragmentation LEBIT project 92 MeV/U 38 Ca/ 37 K Degrader thickness  m efficiency Gas Stopping in use at the NSCL

38. RIA Summer School 2006 GSI experiment S258 Savard(ANL), Scheidenberger (GSI) et al. GSI experiment S258 Savard(ANL), Scheidenberger (GSI) et al. Bragg peak from 56 Ni beam Bragg peak from 54 Co beam Bragg peak from 52 Fe beam 54 Co 52 Fe ~ 50 % of radioactive ions stopped in the gas catcher were extracted as a radioactive ion beam! ANL, GSI, KUL, MSU, RIKEN, … RIA prototype gas catcher tested at GSI

39. RIA Summer School 2006 ANL Upgrade based on 252 Cf Fission Guy Savard, ANL

40. RIA Summer School 2006 ANL ATLAS upgrade: CARIBU

41. RIA Summer School 2006 Yields from the ANL Upgrade Guy Savard, ANL

42. RIA Summer School 2006 SRIM & PIC calculation by M.Facina 0100200300400 500 60 80 100 120 140 160 radial dimension (mm) axial dimension (mm) He + Stopping volume  75 cm 3 Ionization  1.7 x 10 6 IP/ion He + created by a 100 pps 38 Ca beam in 760 Torr

43. RIA Summer School 2006 Cyclotron Gas Stopper Concept Gas-filled weakly-focusing cyclotron magnet w/ RF guiding techniques at end-of-range Low gas pressure  long stopping path  fast drift & extraction Separate He + from rare ions  minimal space-charge Exotic atom studies in a cyclotron trap for antiprotons, pions, and muons L.M. Simons, Hyperfine Interactions 81 (1993) 253 Proposal for a cyclotron ion guide with RF carpet I. Katayama, M. Wada, Hyperfine Interactions 115 (1998) 165 A Study of Gas-Stopping of Intense Energetic Rare Isotope Beams G. Bollen, D.J. Morrissey, S. Schwarz, NIM A550 (2005) 27 Features/Expectations:

44. RIA Summer School 2006 Initial Stopping Calculations degrader 100 MeV/A Br [ 2.6 mm Al ]  610 MeV Br Field B max = 2 T, n = 0.2 10 mbar He Beam simulations of ions in gas-filled weak-focusing magnet by Bollen High space-charge and stopped-ion regions are separated ! Intensity limits > 10 8 /s High space-charge and stopped-ion regions are separated ! Intensity limits > 10 8 /s Energy loss or Ionization density Stopped-ion distribution lies inside dashed circle Top view

45. RIA Summer School 2006 NSCL Stopping Cyclotron (Under Design) Superconducting magnet system B max = 2 T, n = 0.2, r inj = 0.7 m High Energy Beam D.Lawton, A.Zeller (NSCL)

46. RIA Summer School 2006 Beam Simulation including Injection One Trajectory in ‘real’ field Energy vs. Position degrader 100 MeV/A 79 Br on 2.6mm Al  610 MeV 78 Br F. Marti (NSCL)

47. RIA Summer School 2006 Minimizing extraction time Simulations of ion motion on RF carpets in 2 Tesla field Low gas pressure (10 mbar compared to 200 - 1000 mbar in present systems) Time for collection onto carpet and transport out of gas stopper < 5 ms ! Low gas pressure (10 mbar compared to 200 - 1000 mbar in present systems) Time for collection onto carpet and transport out of gas stopper < 5 ms ! RF 400V; 1.5MHz DC gradient 20V/cm Spacing 1 mm, 0.5 mm thick

48. RIA Summer School 2006 NSCL Reacceleration Stage Options Reaccelerated beam area Stage I: 3 MeV/u Stage II: 12 MeV/u

49. RIA Summer School 2006 You ask: Should I switch fields? Construction of a 1 B$ facility in the US in the next 5 years is unlikely There are positive signs (3 rd on the DOE list of facility priorities; congressional mandate of RIA; highest NSAC priority) that something on the scale of 600 M$ will happen This is a very active field world-wide NSCL, TRIUMF, HRIBF, ANL, T A&M, etc. Upgrades at NSCL, ANL, HRIBF Large scale international facilities: FAIR, RIBF, SPRIRAL II, EURISOL, … There are exciting, important questions to answer Construction of a 1 B$ facility in the US in the next 5 years is unlikely There are positive signs (3 rd on the DOE list of facility priorities; congressional mandate of RIA; highest NSAC priority) that something on the scale of 600 M$ will happen This is a very active field world-wide NSCL, TRIUMF, HRIBF, ANL, T A&M, etc. Upgrades at NSCL, ANL, HRIBF Large scale international facilities: FAIR, RIBF, SPRIRAL II, EURISOL, … There are exciting, important questions to answer

50. RIA Summer School 2006 Additional Material

51. RIA Summer School 2006 RIA White Papers One of the best places to find out more information regarding RIA is the RIA users web site. Overall info: http://www.orau.org/ria/ White papers: http://www.orau.org/ria/pubs.htm One of the best places to find out more information regarding RIA is the RIA users web site. Overall info: http://www.orau.org/ria/ White papers: http://www.orau.org/ria/pubs.htm

52. RIA Summer School 2006 Universality of Production Cross Sections Na isotopes

53. RIA Summer School 2006 The production yield of residues saturates with a total beam energy of a few GeV. Limiting Fragmentaton H. Ravn - “The saturation cross-section for more exotic species may well first be reached beyond 5 GeV.” Kaufman and Steinberg, PRC 22 (80) 167. Limiting Fragmentation

54. RIA Summer School 2006 Moretto and Wozniak, Ann. Rev. 45 (93) p + Xe at 48.5 degrees Limiting Fragmentation continues to high energy