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Science with MoNA – Exploring the Unknown

Science with MoNA – Exploring the Unknown. Many nuclei (isotopes) have never been observed The quest for the unknown. Nuclear landscape is largely unexplored. Fundamental Physics. Rocks Crystals Molecules Atoms Nuclei

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Science with MoNA – Exploring the Unknown

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  1. Science with MoNA – Exploring the Unknown • Many nuclei (isotopes) have never been observed • The quest for the unknown • Nuclear landscape is largely unexplored

  2. Fundamental Physics Rocks Crystals Molecules Atoms Nuclei Nucleons Quarks

  3. From Simplicity to Complexity

  4. Limits of Nuclear Stability Heavy Elements? Known Nuclei Predicted Nuclei Never observed Terra Incognita

  5. Valley of Stability

  6. Method of Discovery

  7. Discovery of the Isotopes

  8. Identified Isotopes of Elements 62 Elements 1664 Isotopes

  9. Countries

  10. Fusion evaporation Projectile fragmentation WWII First accelerators Mass spectroscopy Radioactivity

  11. Limits of Nuclear Stability Heavy Elements? Known Nuclei Fission Limit? Proton Drip Line? Neutron Drip Line? Neutron-bound: T1/2 > ms Neutron-unbound: T1/2 < 10-20 s

  12. Lifetimes/Decay-Widths

  13. “Nuclei” in the Chart of Nuclei “The value of Z and N for which the last nucleon is no longer bound and for which the nucleus decays on the timescale of 10-22 s or faster defines the dripline.”

  14. Borromean Nucleus: 11Li Neutron Neutron 9Li

  15. Brunnian Links Robert Scharein Department of Computer Science University of British Columbia http://www.cs.ubc.ca/nest/imager/contributions/scharein/brunnian/brunnian.html http://www.cs.ubc.ca/nest/imager/contributions/scharein/brunnian/brun6-rem3.mpg

  16. National Superconducting Cyclotron Laboratory

  17. NSCL/Coupled Cyclotron Facility • 429 Employees • Faculty of 36 physicists, chemistsand engineers • 65 graduate and 65 undergraduate students • Over 700 outside users • Nuclear physics graduate program ranked #1 in nation

  18. Projectile Fragmentation hot participant zone projectile fragment projectile target Random removal of protonsand neutrons from heavy projectile in peripheral collisions Cooling by evaporation. projectile fragment

  19. Fragmentation Reaction t = -10-22 sec d = -10 fm .00000000000039’’ 18O beam 9Be target t = -5x10-23 sec d = -5 fm 18O 80 MeV/nucleon 40% speed of light 278,000,000 mph 9Be

  20. Production of 11Li t = 0 sec d = 0 fm t = 10-22 sec d = 10 fm 11Li

  21. Production Probability ~10pnA 18O 80 MeV/nucleon ~10,000 9Li ~100 11Li  ~1000 10Li

  22. Example Beyond the Dripline: 25O 25O – 26O are “unbound” 25O decays within 10-21s into 24O and a neutron 26O decays into 24O and two neutrons

  23. Nuclear Physics or Mechanics 26F 25O 40% speed of light 9Be p 9Be p 24O 9Be 24O p n 9Be n

  24. MoNA – Sweeper Setup 9Be(26F,25O)X Secondary Beam neutrons fragments

  25. Sweeper Magnet • Superconducting dipole magnet • central Bρmax 4Tm • 43o deflection angle • 14cm vertical gap • Detectors • two x/y CRDCs • ion chamber • thin and thickplastic scintillators Constructed at the NHMFL at Florida State University

  26. MoNA – Modular Neutron Array An NSF funded collaboration of 10 colleges and universities. • 144 elements arranged in 9 layers of 16 bars • 2m by 1.6m by .9m • Flight paths from 8m to 14m • Time resolution <1ns • Position resolution of 7.5cm

  27. The Modular Neutron Array at the NSCL T. Feder, Physics Today March 2005, p.25 “That’s what NSF is about” (Bob Eisenstein, NSF Assistant Director in 2001)

  28. Construction

  29. Public Relation ‘Dr. Physics’ puts Concordia on the map Luther receives grant from the National Science Foundation IUSB students help build neutron detector

  30. Continued Collaboration • Yearly Meetings at Beaver Island (Central Michigan University) • Collaboration Website (Concordia College) • FPGA programming/ElectronicsData analysis coordination (Hope College) • Data storage (Indiana University at South Bend) • Public relation (Marquette University) • Data analysis code checks (Wabash College) • Cosmic-rays calibration (Westmont College)

  31. Previous Setup MoNA – Sweeper Setup

  32. The Move

  33. New Location MoNA – Sweeper Setup

  34. Particle Identification 29Na 26F Z = 8 24O

  35. 25O Resonant decay spectrum Decay 820(20) keV Width 90(30) keV ħ =   = 710-21 s

  36. Results for 25O 1.5 1.0 Decay Energy 0.5 25O 0.0 24O + n Exp. Result Continuum Shell Model A. Volya and V. Zelevinsky, PRL. 94, 052501 (2005)

  37. Two-Neutron Decay of 26O En = -981 keV 24O 25O 26O 26O bound !? T1/2 = 0.4 fs En = 820 keV

  38. 25O Experimenters C. Hoffman, T. Baumann, D. Bazin, J. Brown, G. Christian,P. DeYoung, J. Finck, N. Frank, J. Hinnefeld, R. Howes,P. Meers, E. Mosby, S. Mosby, J. Reith, B. Rizzo,W. Rogers, G. Peaslee, W. Peters, A. Schiller,M. Scott, S. Tabor, P. Voss, T. Williams

  39. Our present view of the nucleus is limited… Some Basic Nuclear Property

  40. In the future we will greatly expand our horizons

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