Brent Fultz Prof. Materials Science and Applied Physics California Institute of Technology

1. Science and Project History • Instrument Characteristics • Project Risks in 2001 and 2004 • -Technical • -Management • Cost and Schedule Highlights • Software Brent Fultz Prof. Materials Science and Applied Physics California Institute of Technology Doug Abernathy Instrument Scientist Spallation Neutron Source Kevin Shaw Engineer Spallation Neutron Source

3. (incoherent, inelastic) vs. (coherent, inelastic)

4. Inelastic

5. Magnetic Excitations • Energy of the excitations can be large, often beyond • the spectrum from reactor sources. • d- and f-electron form factors are large in r, small in k • For small Q and high Ei, forward detector coverage • must be good.

6. Examples of Magnetic Excitations • KCuF3 – a 1D • Heisenberg antiferromagnet • quantized excitations in • spin chain • calculated by field theory: • sharp dispersive modes • continuum from • free spinons (not FD or BE)

7. Phonon Scattering Thermodynamics of materials T = 0 all internal coordinates in ground state. T > 0 creates excitations. Degeneracy of excitations gives entropy S = k lnW. F = E – TS favors different structures of materials. (Parallel thermodynamics for magnetic scattering.)

9. Everybody wants More Flux! • No inelastic neutron scattering experiment has ever • suffered from excessive flux • SNS source and p steradian detector coverage • will give ARCS new capabilities in practice: • 1. Parametric studies • Present -- compare A vs. B. Future -- A(T,H) vs. B(T,H) • 2. Single crystals • 3. Small quantities of new materials • 4. Sample environments

10. Multipurpose ARCS (mid-2001)

11. Bifurcation of ARCS (early 2002) • Full instrument had no contingency funds • Canadian CFI program prompted interest in a • second high-energy chopper instrument • International class facility should have a general • purpose and a magnetism instrument

13. ARCS Main Components Conventional Facilities Shutter Guides Software Choppers Sample Isolation System Detector Array Scattering Tank Shielding

15. McStas Simulations of Beams on Sample ARCS source Chopper: 63 meV 250 meV 0.5 mm slits 600 Hz

16. McStas Simulation of Diffraction (1) ARCS source Chopper: 63 meV 1.14A 3mm slits, 480 Hz Perfect crystal (selects neutrons of incident angle) (004) diamond, 2q=79.6 deg ARCS detector Horiz = tube spacing Vert = measured resolution

17. McStas Simulation of Diffraction (2) McStas Result: DQhoriz = 1.6% DQvert = 1.1% (improves with 2q) Get trend from calculations assuming: 0.5 deg detector spacing DE/E = 0.02

18. Flux on Sample at 63 meV

19. Flux on Sample at 250 meV

20. ARCS

21. 2001/2002 2004 Project Risks Sample Isolation Shielding Background Detectors in Vacuum Shielding (with SEQUOIA) Single Crystal Capabilities Fermi Chopper Sample Isolation Management Technical SNS/Caltech Interactions Project Controls Budget (balance: hardware vs. engineering) Schedule

22. ARCS Project Budget Proposed Hardware: 10 M$ (spent/committed 0 M$) Contingency: 2 M$ (20% of remaining) Software: 2.9 M$ (spent/committed 0 M$) Present Hardware: 11 M$ (spent/committed 3.6 M$) Contingency: 1 M$ (14% of remaining) Software: 2.9 M$ (spent/committed 1.3 M$) Software effort is 0.58 M$/year for postdoctoral fellows, professionals, graduate students, and a relatively small amount for hardware

23. Tech Risk #1Detector Tubes in Vacuum Modules with 8 detectors,analog and some digital electronics, readout card operated inside the instrument vacuum tank.

24. Test Program for Detector Tubes in Vacuum • Modules operated 3 months with no problem • Highest temperatures 10-15 C above ambient • No outgassing problems or contamination of high potential surfaces • Noise figures unchanged (2 counts/minute over all 8 tubes) • Tests ongoing.

25. Tech Risk #2: Shielding • Biological shield effectiveness (we can meet the 0.25 mR/hr) • Crosstalk between instruments (heavy T_0 choppers) • Background (difficult to calculate well)

26. Tech Risk #2: Shielding Design MCNPX Calculations E. Iverson, D. Abernathy Dose rates outside beamline 0.1 mrem/hr Optimization possible blue: steel yellow: HD concrete red borated poly turquoise: regular concrete

27. Tech Risk #2: Background? Neutron dose rates: with steel sample, choppers open without sample, Fermi chopper closed

28. Tech Risk #2: Background? Neutron count rates: with steel sample, choppers open without sample, Fermi chopper closed

29. Tech Risk #3 3-Axis Cryogenic Goniometer Sumitomo cryocooler Kohzu components Designed for first operations on Pharos instrument at LANL 180o 10o 10o Heavy copper Litz wire Sample Thermal isolator

30. Tech Risk #4 Fermi Chopper System • Moveable Fermi choppers • Two independent control units • Can move while spinning if accelerations and jerk are low • Open beam also

31. Tech Risk #4 Fermi Chopper System • Finite element stress calculations in elastic range • All material below yield stress

32. Tech Risk #5 Sample Isolation System

33. Tech Risk #5 Sample Insertion (Pharos)

34. Tech Risk #5 Sample Isolation System opening closed main vacuum

35. Tech Risk #5 Sample Isolation System

36. Mgmt. Risk #1 - SNS/Caltech Interactions • MOA (signed in 1 day by Caltech Provost) • Visitor Status of Doug Abernathy • Purchasing through Caltech - small items: office staff - evaluated procurements: buyers and lawyers • Project communications adequate

37. Mgmt. Risk #2 - Project Controls • Data reporting with project plan started working at Argonne • New system at ORNL -- follow the SING instruments • Today’s review kick-started the ORNL project controls support.

38. DOE BES Engineering [FY] Installation [FY] Hardware Software [various] ANL Caltech ORNL WFO WFO Mgmt. Risk #3 - Funding Channels

39. 1 yr Target Bldg. Ready for Equipment: 9/1/03 Beneficial Occupancy: 6/1/04 Beneficial Occupancy: March 05 Budget Profiles 2001/2002 Aug. 2004

40. Major Procurements - Highlights Completed or Contract Issued • Detector tubes • Fermi Choppers • Core vessel insert and shutter insert • Guide in shutter • Shielding (poured in place) Request for Proposals Imminent (specs under review) • Main guide • Sample isolation system • Vacuum tank/pumping system • T0 chopper Engineering Underway • Shielding around tank • Sample hutch

41. Software Roadmap v. 1.0

42. Data Reduction • Third generation code for polycrystalline samples • First generation for single crystal data reduction. Needs data from real experiments. • Visualization needs attention (commercial packages?) Data Modeling • Full suite of phonon dynamics codes • Classical magnetics dynamics Full Simulations • McStas bindings for Pyre framework underway.

43. Software Milestones Software Baseline Design January, 2003 Software First Build July, 2004 Software Beta Release March, 2005 Software Release 1.0 February, 2006 End ARCS Project September, 2006

44. DANSE • NSF has funded 1 yr design ($ 985,000) • Construction proposal in preparation

45. Summary • Cost (comfortable) • Schedule (tight but possible) • What it will be in Sept. 2006: - Working instrument (parameters essentially as promised, but energy resolution depends on moderator modeling) - Probably with a complete detector array - More than basic data reduction and visualization - Some single crystal capability - Limited time to minimize background

46. End of Presentation