The Future of Nuclear Astrophysics in the UK

The Future of Nuclear Astrophysics in the UK Alex Murphy Nuclear astrophysics http: //www. ph. ed. ac. uk/nuclear/ 22 May 2007 Cosener's House Dark Matter http: //hepwww. rl. ac. uk/ukdmc. html/ 1

Outline n Who we are n What we do n The Future: Three examples n Other projects/programmes n Summary 22 May 2007 Cosener's House 2

Who we are… n In virtually every nuclear physics proposal, at some point there are the words ‘…is of Astrophysical relevance…’ n Significant contributions from many nuclear physicists n It is highly multidisciplinary and interdisciplinary n Specialist groups in the UK are: Edinburgh & York ~6 Academic Staff, +RA. s, +Students 22 May 2007 Cosener's House 3

What we do… Aims of Nuclear Astrophysics n An understanding of the origin & evolution of the elements n An understanding of the mechanisms driving astrophysical phenomena Timeliness n Remarkable observations from new telescopes. n New experimental facilities and techniques Our role is to provide the key nuclear inputs that are needed 22 May 2007 Cosener's House 4

These are important questions! “How were the elements from iron to uranium made? ” abundance Abundance curve of the elements Fe Mass number “The 11 Greatest Unanswered Questions of Physics” National Academy of Science Report, Committee for the Physics of the Universe, 2002 22 May 2007 Cosener's House 5

Our Science Objectives: n n n How were the elements from iron to uranium made? What leads to the abundances observed in novae? Artist’s conception What governs other explosive phenomena? Crab Nebula SN 1054 n What is the role of nuclear physics in stellar evolution? 22 May 2007 Cosener's House Chandra observation 6

World Context: The desire to understand astrophysical phenomena is a major motivation for significant investment in new facilities around the world. n n n Europe: FAIR, REX-ISOLDE upgrade, SPIRAL-II, Eurisol US: Facility for Rare Isotope Beams Canada: ISAC-II Japan: Big. RIPS China: HIRFL (Lanzhou) … The UK has a strong track record and is well placed to play a major role in these activities 22 May 2007 Cosener's House 7

The Future: Three examples… AIDA TACTIC 22 May 2007 Cosener's House 8

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 n n 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_v 1. pdf 22 May 2007 Cosener's House 9

AIDA: Science Case Recent Observations of Metal Poor Stars n n 22 May 2007 Cosener's House [Fe/H] < -3. 0 ‘Unique’ r-process What is its site? How does it operate? 10

R-process studies R – abundances Details of nuclear properties 132 Cd 48 82 Z N neutrons protons Key sources of uncertainty are the properties of highly neutron rich nuclei 22 May 2007 Cosener's House 11

FAIR GSI today 22 May 2007 Future facility Cosener's House 12

AIDA Concept § § § R-process nuclei implanted into multi-plane, highly segmented DSSD array Observe subsequent decays: p, 2 p, , 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 22 May 2007 Cosener's House 13

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 n Further information: http: //tactic. triumf. ca/ 22 May 2007 Cosener's House 14

Why TACTIC? n Allows exploration of previously impossible-to-access reactions n n n Gas targets Low energies Tracking Particle ID Direct measurements Large solid angle / High efficiency Radiation Hard Can be complemented with -ray array Optimised for 8 Li( , n) : But much more too! Opens up many new scientific possibilities Radical, adventurous project for UK nuclear physics 22 May 2007 Cosener's House 15

Schematic design of TACTIC detector - - - - GEM readout 22 May 2007 Cosener's House n Design: Completed 16

TACTIC: Status n n 22 May 2007 Construction: Almost complete In-beam testing: Aug 2007 Cosener's House 17

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 22 May 2007 Cosener's House 18

ELENA Motivation n Cosmic ray induced backgrounds hamper rare event searches n Key astrophysical important reactions would be much better studied in a cosmic ray free environment n There exists an underground science laboratory in the UK at Boulby Proposal n An underground low energy accelerator for nuclear astrophysics 22 May 2007 Cosener's House 19

Boulby Mine Ø Ø a working potash and salt mine Cleveland - North East England the deepest mine in Britain (850 m to 1. 3 km deep) Middlesborough Staithes Whitby York Sylvanite 22 May 2007 Cosener's House 20 courtesy: S. Paling

Underground science established 1 km Mine Shafts Dark Matter Research Areas Map of excavations 22 May 2007 Cosener's House 21

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) 2805 mwe attenuates CR by ~106 Salt is low in Uranium & Thorium Plenty of Laboratory space Virtually unlimited potential for expansion Easy access for equipment Via mine shaft (4 m lengths) + Transport underground Good infrastructure + facilities JIF laboratory, CPL Support 22 May 2007 Cosener's House 22

Why is Boulby Special? Advantage of salt mine: extremely low background at E < 2 -3 Me. V Gran Sasso Boulby 22 May 2007 Cosener's House 23

What will be involved? Ion (charge state) Particles per second H+ 5. 0 x 1014 He+ 5. 0 x 1013 He 2+ 1. 0 x 1013 Xe 17+ 2. 9 x 1012 Kr 15+ 4. 1 x 1011 Ar 11+ 5. 6 x 1011 Ne 6+ 1. 0 x 1012 Fe 11+ 5. 7 x 1011 (estimated) Ni 11+ 5. 7 x 1011 (estimated) Ø 3 MV single-ended machine (e. g. NEC, Pelletron) Ø ECR source (e. g. for high intensity (~500 m. A) 12 C beam at high charge states) Ø Beam-lines + detection systems (gamma, neutron, charged particles) 22 May 2007 Cosener's House 24

Is there a role for ELENA? Only other comparison is LUNA at the Gran Sasso n …a 400 k. V machine n n Limited to acceleration of H and He beams Only direct kinematics studies are possible n n n beam-induced background on target impurities a problem Reactions producing neutrons are not allowed Space limited Key studies: n n n Carbon burning in advanced stages of stellar evolution Neutron sources for s-process Ne, Na, Mg and Al nucleosynthesis in AGB stars 22 May 2007 Cosener's House 25

ELENA n n n Statement of Interest has been submitted to STFC Background level ~ factor 1030 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 in Edinburgh July 2007 22 May 2007 Cosener's House 26

Not enough time to mention… 22 May 2007 Cosener's House 27

TIGRESS-SHARC n n York contribution to TIGRESS Light ion transfer reactions E. g. 59, 60 Fe(d, p) to determine supernova (n, ) rates New silicon barrel and Bragg detector 22 May 2007 Cosener's House 28

ERAWAST Exotic Radionuclides from Accelerator Waste for Science and Technology n n n 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. 44 Ti (t½ = 60 yr) 44 Ti( , p), relevant to 44 Ti abundance in SNe Rate is needed to allow comparison of -ray observation of 44 Ti with core collapse models Unique diagnostic of the collapse mechanism 22 May 2007 Cosener's House 29

Ongoing programmes of research Louvain-la-Neuve § Pioneering radioactive nuclear beams. § LEDA – Pioneering large segmented Si § Measuring nuclear properties relevant to novae & XRBs 22 May 2007 Cosener's House 30

Ongoing programmes of research TRIUMF TUDA 22 May 2007 Cosener's House 31

Other ongoing/planned activities Plus, unique needs of certain experiments require activity at other locations, e. g. n ANL n REX-ISOLDE n GANIL n Orsay n ORNL n ANU n … 22 May 2007 Cosener's House 32

Summary Exciting Science New Ideas New Scientific Opportunities Use of Many Experimental Techniques 22 May 2007 Cosener's House 33

n Extra slides 22 May 2007 Cosener's House 34

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25, 26 Al(p, )26, 27 Si reactions influence predicted flux of the cosmic γ-ray emitter 26 Al 22 May 2007 Cosener's House 40

some key reactions: 14 O( , p)17 F 27 Si 18 Ne( , p)21 Na(p, )22 Mg 28 Si 27 Al 24 Al 15 O( , )19 Ne rp-process onset 25 Al 26 Al 25 Mg 21 Mg 22 Mg 23 Mg 24 Mg 20 Na 19 Ne(p, )20 Na 21 Na 22 Na 23 Na 20 Na(p, )21 Mg Ne. Na cycle HCNO breakout 18 F(p, )15 O 26 Mg 18 Ne 20 Ne 17 F 26 Al(p, )27 Si 19 Ne 18 F 21 Ne 22 Ne 19 F (p, ) 14 O 15 O 16 O 13 N 14 N 15 N 12 C 13 C 17 O 18 O ( , p) (p, ) HCNO 22 May 2007 Cosener's House ( , ) (b+) stable unstable 41

Hot CNO Cycle T~3*108 K T 1/2=1. 7 s r~ 103 gm. cm-2 3 a flow Key unknown reaction rates are dominated by resonance reactions 17 F(p, )18 Ne, 14 O( , p)17 F, 18 F(p, )15 O Experiments require intense radioactive beams ~1 Me. V/u 22 May 2007 Cosener's House 42

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 cycle after breakout via: T 8 ≥ 3 15 O( , )19 Ne T 8 ≥ 6 18 Ne( , p)21 Na 3 a flow 22 May 2007 Cosener's House 43

12 C+12 C importance: Gamow region: min. measured E: evolution of massive stars 1 – 3 Me. V 2. 1 Me. V (by -ray spectroscopy) passive lead & concrete shielding 12 C(12 C, )20 Ne and 12 C(12 C, p)23 Na channels Crab Nebula SN 1054 Spillane et al PRL 98 (2007) 122501 channel Aguilera et al. PRC 73 (2006) 64601 p channel Major improvements expected for measurements underground! 22 May 2007 Cosener's House 44

13 C( , n)16 O importance: Gamow region: min. measured E: s-process in AGB stars 130 - 250 ke. V 270 ke. V M. Heil, Ph. D Thesis - Karlsruhe, 2002 Contributions from sub-threshold states? Mainly hampered by cosmic background good case for underground investigation 22 May 2007 Cosener's House 45

22 Ne( , n)25 Mg importance: Gamow region: min. measured E: s-process in AGB stars 400 - 700 ke. V ~550 ke. V Jaeger PRL 87 (2001) 202501 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 22 May 2007 22 Ne( , )25 Mg Cosener's House reaction Karakas et al Ap. J 643 (2006)46 471

Abundances of Ne, Na, Mg, Al, … in AGB stars and nova ejecta affected by many (p, ) and (p, ) reactions Iliadis et al. Ap. J S 134 (2001) 151; S 142 (2002) 105; Izzard et al A&A (2007) submitted !! new measurements underground are very much needed !! 22 May 2007 Cosener's House 47

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 22 May 2007 Cosener's House 48