1. Past and Future Insights from Neutron Scattering Collin Broholm * Johns Hopkins University and NIST Center for Neutron Research  Virtues and Limitations of Neutron Scattering  New Sources and Instrumentation  Capabilities of New Instrumentation  Conclusions * supported by NSF DMR-0074571

2. Fisk Fest 8/15/01 Zachary Fisk and Neutron Scattering  More than 70 papers on neutron scattering:  Heavy Fermion Systems  Kondo Insulators  Valence Fluctuating systems  High T C superconductors  Neutrons used to probe  Magnetic order and Fluctuations  Structure and sample quality  Thermal Expansion  Phonons

3. Fisk Fest 8/15/01 Spin Fluctuations in U 2 Zn 17 Broholm et al. PRL (1987)

4. Fisk Fest 8/15/01 Structure of YbInCu 4 d-spacing (A) Intensity (10 3 counts/  s) Lawrence et al PRB (1996) Contrast between elements with similar Z Sensitivity to light atoms in heavy matrix Contrast between elements with similar Z Sensitivity to light atoms in heavy matrix a probe of sample quality Flux-grown crystal

5. Fisk Fest 8/15/01 Magnetic Structure of CeRhIn 5 Bao et al PRB (2000)

6. Fisk Fest 8/15/01 Probing Spin Density Distribution UPt 3 U 5f, 6d, and -7f spin polarization Pt polarized as well U 5f, 6d, and -7f spin polarization Pt polarized as well UBe 13 Only U polarized Neumann, Brown, et al. Physica B (1991)

7. Fisk Fest 8/15/01 Electronic Interactions in La 2 CuO 4 Coldea et al PRL (2001)

8. Fisk Fest 8/15/01 What makes it hard  150 MeV thermal energy per neutron (fission)  a factor Z 2 less than X-ray scattering  Limitations of current instrumentation  dynamics in samples < 1 mm 3  dynamics in nano-structured solids  Lateral surface structure  complex materials with weak signals  Signals from impurities at low concentration  Spatial and temporal resolution  Pressure above 25 GPa

9. Fisk Fest 8/15/01 Expanding Applicability of a Powerful Probe  Increase source brightness  Increase spectral brightness by cooling neutrons  Increase temporal brightness in pulsed neutron source  Improve beam delivery system  Match solid angle to wave vector resolution requirements  Match bandwidth to energy resolution requirements  Increase solid angle of detection system  Position sensitive detectors  Crystal analyzer arrays

10. Fisk Fest 8/15/01 New Instrumentation and Sources  NIST cold source and instrument upgrade 2002-4  HFIR cold source and instrument upgrade 2002  LANSCE source and instrument upgrade 2002  US Spallation Neutron Source 2006  German high flux research reactor 2004  Australian high flux research reactor 2005  Japanese Spallation Neutron Source 2006  European Spallation Neutron Source ?  Chinese Advanced Research reactor ?

11. InstrumentBegin  E (meV) Condensed Matter Science Enabled FANS19991-3Phonon Density of States Spin Echo200010 -5 Flux lattice dynamics Dynamic Correlations in Glasses Back Scattering199910 -3 Critical Phenomena Quantum Tunelling Disc Chopper200110 -2 -1Quantum Critical phenomena Phonon density of states MACS200410 -2 -1Structure of fluctuating systems Impurity dynamics Inelastic Scattering from small samples New Instruments for CMP at NIST

12. Fisk Fest 8/15/01 Intensity from Focusing 1428 cm 2 PG(002) MC Simulation Qiu and Broholm (2001) MACS monochromator

13. Fisk Fest 8/15/01 Upgraded Neutron Scattering Facilities at HFIR, ORNL

14. Upgraded Neutron Scattering Facilities at LANSCE

15. Fisk Fest 8/15/01

16. May 2001 Aug 7 2001

17. Instruments for CMP at SNS

18. Fisk Fest 8/15/01 Neutrons in the 21 century  Chemical and magnetic structure at the interfaces of nano- scale artificially structured systems  Excitations in materials patterned on the nano-scale  Protein structure (including D-positions) and dynamics  Complete 4 D Q-E mapping of dynamic correlation function for spin and lattice in large single crystals 0<E<100 meV  Systematic access to order parameters of weak or complex broken symmetry phases  Inelastic neutron scattering as a super-susceptometer for screening new materials  Parametric and complete information about structure of matter under extreme conditions

19. Fisk Fest 8/15/01 Conclusions  Neutrons are great but we don’t have enough yet  New sources and instrumentation should produce a renaissance for the technique  New facilities must be easily accessible to non- neutron-experts to broaden the science program