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Alex Murphy

The Future of Nuclear Astrophysics in the UK. Alex Murphy. Nuclear astrophysics http://www.ph.ed.ac.uk/nuclear/. Dark Matter http://hepwww.rl.ac.uk/ukdmc/ukdmc.html/. Outline. Who we are What we do The Future: Three examples Other projects/programmes Summary. Who we are….

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Alex Murphy

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  1. The Future of Nuclear Astrophysics in the UK Alex Murphy Nuclear astrophysics http://www.ph.ed.ac.uk/nuclear/ Cosener's House Dark Matter http://hepwww.rl.ac.uk/ukdmc/ukdmc.html/

  2. Outline • Who we are • What we do • The Future: Three examples • Other projects/programmes • Summary Cosener's House

  3. Who we are… • In virtually every nuclear physics proposal, at some point there are the words ‘…is ofAstrophysical relevance…’ • Significant contributions from many nuclear physicists • It is highly multidisciplinary and interdisciplinary • Specialist groups in the UK are: Edinburgh & York ~6 Academic Staff, +RA.s, +Students Cosener's House

  4. What we do… Aims of Nuclear Astrophysics • An understanding of the origin & evolution of the elements • An understanding of the mechanisms driving astrophysical phenomena Timeliness • Remarkable observations from new telescopes. • New experimental facilities and techniques Our role is to provide the key nuclear inputs that are needed Cosener's House

  5. These are important questions! “How were the elements from iron to uranium made?” Abundance curve of the elements Fe abundance Mass number “The 11 Greatest Unanswered Questions of Physics” National Academy of Science Report, Committee for the Physics of the Universe, 2002 Cosener's House

  6. Crab Nebula SN 1054 Artist’s conception Chandra observation Our Science Objectives: • How were the elements from iron to uranium made? • What leads to the abundances observed in novae? • What governs other explosive phenomena? • What is the role of nuclear physics in stellar evolution? Cosener's House

  7. World Context: The desire to understand astrophysical phenomena is a major motivation for significant investment in new facilities around the world. • Europe: FAIR, REX-ISOLDE upgrade, SPIRAL-II, Eurisol • US:Facility for Rare Isotope Beams • Canada: ISAC-II • Japan: BigRIPS • China: HIRFL (Lanzhou) • … The UK has a strong track record and is well placed to play a major role in these activities Cosener's House

  8. AIDA TACTIC The Future: Three examples… Cosener's House

  9. Advanced Implantation Detector Array (AIDA) Scientific Motivation: The r-process Collaboration: The University of Edinburgh (lead) The University of Liverpool CCLRC DL & RAL Project Manager: Tom Davinson • Further information:http://www.ph.ed.ac.uk/~td/AIDA • Technical Specification: http://www.ph.ed.ac.uk/~td/AIDA/Design/AIDA_Draft_Technical_Specification_v1.pdf Cosener's House

  10. AIDA: Science Case Recent Observations of Metal Poor Stars • [Fe/H] < -3.0 • ‘Unique’ r-process • What is its site? • How does it operate? Cosener's House

  11. R-process studies 132Cd 48 82 R –abundances Details of nuclear properties Z N protons neutrons Key sources of uncertainty are the properties of highly neutron rich nuclei Cosener's House

  12. FAIR GSI today Future facility Cosener's House

  13. AIDA Concept • R-process nuclei implanted into multi-plane, highly segmented DSSD array • Observe subsequent decays: p, 2p, a, b, g,bp, bn … • Measure half lives, branching ratios, decay energies … • Tag interesting events for coincident gamma and neutron detector arrays • Long half-lives, requiring high segmentation •  4096 channels & Application Specific Integrated Circuits Significant advance on present technology Cosener's House

  14. TRIUMF Annular Chamber for Tracking and Identification of Charged particles (TACTIC) Scientific Motivation: Direct measurements of low energy nuclear astrophysical reactions using radioactive beams Collaboration: The University of York (lead) TRIUMF, Canada (ACTAR-EURONS) Project leader: Alison Laird • Further information:http://tactic.triumf.ca/ Cosener's House

  15. Why TACTIC? • Allows exploration of previously impossible-to-access reactions • Gas targets • Low energies • Tracking • Particle ID • Direct measurements • Large solid angle / High efficiency • Radiation Hard • Can be complemented with g-ray array • Optimised for 8Li(a,n) : But much much more too! • Opens up many new scientific possibilities • Radical, adventurous project for UK nuclear physics Cosener's House

  16. Schematic design of TACTIC detector • Design: Completed - - - - - - - - GEM readout Cosener's House

  17. TACTIC: Status • Construction: Almost complete • In-beam testing: Aug 2007 Cosener's House

  18. Experimental Low Energy Nuclear Astrophysics (ELENA) Scientific Motivation: Direct measurements nuclear astrophysical reactions at the Gamow energy Proposer: The University of Edinburgh Marialuisa Aliotta Technical Specification: Contact: Marialuisa Aliotta Cosener's House

  19. ELENA Motivation • Cosmic ray induced backgrounds hamper rare event searches • Key astrophysical important reactions would be much better studied in a cosmic ray free environment • There exists an underground science laboratory in the UK at Boulby Proposal • An underground low energy accelerator for nuclear astrophysics Cosener's House

  20. Middlesborough Staithes Whitby York Boulby Mine • a working potash and salt mine • Cleveland - North East England • the deepest mine in Britain • (850m to 1.3km deep) Sylvanite Cosener's House courtesy: S. Paling

  21. Mine Shafts Dark Matter Research Areas Map of excavations Underground science established 1km Cosener's House

  22. Why is Boulby Special? Requirements for an underground lab... • Low Backgrounds • Deep (to shield from cosmic rays) • Low background rock/lab • (and/or adequate shielding) • Plenty of Laboratory space • Easy access for equipment • Good infrastructure + facilities 2805 mwe attenuates CR by ~106 Salt is low in Uranium & Thorium Virtually unlimited potential for expansion Via mine shaft (4m lengths) + Transport underground JIF laboratory, CPL Support Cosener's House

  23. Why is Boulby Special? Advantage of salt mine: extremely low g background at Eg < 2-3 MeV Gran Sasso Boulby Cosener's House

  24. What will be involved? • 3 MV single-ended machine (e.g. NEC, Pelletron) • ECR source (e.g. for high intensity (~500 mA) 12C beam at high charge states) • Beam-lines + detection systems (gamma, neutron, charged particles) Cosener's House

  25. Is there a role for ELENA? Only other comparison is LUNA at the Gran Sasso • …a 400 kV machine • Limited to acceleration of H and He beams • Only direct kinematics studies are possible • beam-induced background on target impurities a problem • Reactions producing neutrons are not allowed • Space limited Key studies: • Carbon burning in advanced stages of stellar evolution • Neutron sources for s-process • Ne, Na, Mg and Al nucleosynthesis in AGB stars Cosener's House

  26. ELENA • Statement of Interest has been submitted to STFC • Background level ~ factor 10-30 lower than at GS • No space constraints (no interference with other experiments) • Existing support and safety facilities • Opportunities for involvement at various level Workshop planned inEdinburgh July 2007 Cosener's House

  27. Not enough time to mention… Cosener's House

  28. TIGRESS-SHARC • York contribution to TIGRESS • Light ion transfer reactions • E.g. 59,60Fe(d,p) to determine supernova (n,g) rates • New silicon barrel and Bragg detector Cosener's House

  29. ERAWAST Exotic Radionuclides from Accelerator Waste for Science and Technology • See next month’s Nuclear Physics News. • Aim is to make use of long lived radionuclides that have built up from irradiation of the PSI beam dumps • E.g. 44Ti (t½ = 60 yr) • 44Ti(a,p), relevant to 44Ti abundance in SNe • Rate is needed to allow comparison of g-ray observation of 44Ti with core collapse models • Unique diagnostic of the collapse mechanism Cosener's House

  30. Ongoing programmes of research Louvain-la-Neuve • Pioneering radioactive nuclear beams. • LEDA – Pioneering large segmented Si • Measuring nuclear properties relevant to novae & XRBs Cosener's House

  31. Ongoing programmes of research TRIUMF TUDA Cosener's House

  32. Other ongoing/planned activities Plus, unique needs of certain experiments require activity at other locations, e.g. • ANL • REX-ISOLDE • GANIL • Orsay • ORNL • ANU • … Cosener's House

  33. Exciting Science New Ideas New Scientific Opportunities Use of Many Experimental Techniques Summary Cosener's House

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  40. 25,26Al(p,)26,27Si reactions influence predicted flux of the cosmic γ-ray emitter 26Al Cosener's House

  41. (p,) (,) (,p) (p,) (b+) some key reactions: 14O(a,p)17F 18Ne(a,p)21Na 21Na(p,g)22Mg 15O(a,g)19Ne 19Ne(p,g)20Na 20Na(p,g)21Mg 18F(p,a)15O 26Al(p,g)27Si 27Si 28Si 27Al 24Al 25Al 26Al rp-process onset 21Mg 22Mg 23Mg 24Mg 25Mg 26Mg 23Na 20Na 21Na 22Na NeNa cycle HCNO breakout 18Ne 19Ne 20Ne 21Ne 22Ne 17F 18F 19F 14O 15O 16O 17O 18O HCNO 13N 14N 15N stable 13C 12C unstable Cosener's House

  42. Hot CNO Cycle T~3*108 K r~ 103 gm.cm-2 T1/2=1.7s 3a flow Key unknown reaction rates are dominated by resonance reactions 17F(p,g)18Ne, 14O(a,p)17F, 18F(p,a)15O Experiments require intense radioactive beams ~1 MeV/u Cosener's House

  43. For X-ray bursters a similar scenario prevails although in this case material accretes onto the surface of a neutron star rather than a white dwarf Consequently higher T and r can result in breakout from the hot CNO cycles breakout processing beyond CNO cycleafter breakout via: T8≥ 3 15O(a,g)19Ne T8≥ 6 18Ne(a,p)21Na 3a flow Cosener's House

  44. Crab Nebula SN 1054 Aguilera et al. PRC 73 (2006) 64601 Spillane et al PRL 98 (2007) 122501 a channel p channel 12C+12C importance: evolution of massive stars Gamow region: 1 – 3 MeV min. measured E: 2.1 MeV (by g-ray spectroscopy) passive lead & concrete shielding 12C(12C,a)20Ne and12C(12C,p)23Na channels Major improvements expected for measurementsunderground! Cosener's House

  45. 13C(,n)16O importance: s-process in AGB stars Gamow region: 130 - 250 keV min. measured E: 270 keV M. Heil, PhD Thesis - Karlsruhe, 2002 Contributions from sub-threshold states? Mainly hampered by cosmic background  good case for underground investigation Cosener's House

  46. Jaeger PRL 87 (2001) 202501 22Ne(,n)25Mg importance: s-process in AGB stars Gamow region: 400 - 700 keV min. measured E: ~550 keV mainly hampered by cosmic background  good case for underground investigation reaction rate still uncertain by orders of magnitude uncertain nucleosynthesis predictions Similar considerations apply also to 22Ne(a,g)25Mg reaction Cosener's House Karakas et al ApJ 643 (2006) 471

  47. Abundances of Ne, Na, Mg, Al, … in AGB stars and nova ejecta affected by many (p,g) and (p,a) reactions Iliadis et al. ApJ S134 (2001) 151; S142 (2002) 105; Izzard et al A&A (2007) submitted !! new measurements undergroundare very much needed !! Cosener's House

  48. The Playground M.S. Smith and K.E. Rehm, Ann. Rev. Nucl. Part. Sci, 51 (2001) 91-130 The vast majority of reactions encountered in these processes involve UNSTABLE species Cosener's House

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