Supernovae and Neutrinos

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The Future of Nuclear Astrophysics in the UK
Alex Murphy
Nuclear astrophysics http//www.ph.ed.ac.uk/nuclea
r/
Dark Matter http//hepwww.rl.ac.uk/ukdmc/ukdmc.htm
l/
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Outline

• Who we are
• What we do
• The Future Three examples
• Other projects/programmes
• Summary

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Who we are

• In virtually every nuclear physics proposal, at
  some point there are the words is of
  Astrophysical 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
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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

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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
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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?

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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
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The Future Three examples
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Advanced Implantation Detector Array (AIDA)
Scientific Motivation The r-process Collabora
tion 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/AI
  DA
• Technical Specification
• http//www.ph.ed.ac.uk/td/AIDA/Design/AIDA_Draft_
  Technical_Specification_v1.pdf

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AIDA Science Case
Recent Observations of Metal Poor Stars

• Fe/H lt -3.0
• Unique r-process
• What is its site?
• How does it operate?

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R-process studies
R abundances
Details of nuclear properties
Z
N
neutrons
protons
Key sources of uncertainty are the properties of
highly neutron rich nuclei
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FAIR
GSI today
Future facility
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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

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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/

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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

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Schematic design of TACTIC detector
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• Design Completed

GEM readout
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TACTIC Status

• Construction
• Almost complete

• In-beam testing
• Aug 2007

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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
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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

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Boulby Mine

• a working potash and salt mine
• Cleveland - North East England
• the deepest mine in Britain
• (850m to 1.3km deep)

Sylvanite
courtesy S. Paling
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Underground science established
1km
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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
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Why is Boulby Special?
Advantage of salt mine extremely low g
background at Eg lt 2-3 MeV
Gran Sasso
Boulby
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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)

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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

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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 in Edinburgh
• July 2007

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• Not enough time to mention

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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

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ERAWAST
Exotic Radionuclides from Accelerator Waste for
Science and Technology

• See next months 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

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Ongoing programmes of research

• Louvain-la-Neuve

• Pioneering radioactive nuclear beams.
• LEDA Pioneering large segmented Si
• Measuring nuclear properties relevant to novae
  XRBs

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Ongoing programmes of research

• TRIUMF

TUDA
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Other ongoing/planned activities

• Plus, unique needs of certain experiments require
  activity at other locations, e.g.
• ANL
• REX-ISOLDE
• GANIL
• Orsay
• ORNL
• ANU

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Summary
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• Extra slides

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25,26Al(p,?)26,27Si reactions influence predicted
flux of the cosmic ?-ray emitter 26Al
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some key reactions 14O(a,p)17F 18Ne(a,p)21Na
21Na(p,g)22Mg 15O(a,g)19Ne 19Ne(p,g)20Na 2
0Na(p,g)21Mg 18F(p,a)15O 26Al(p,g)27Si
27Si
28Si
25Al
24Al
26Al
27Al
rp-process onset
21Mg
22Mg
23Mg
24Mg
25Mg
26Mg
21Na
22Na
20Na
23Na
NeNa cycle
HCNO breakout
18Ne
20Ne
19Ne
21Ne
22Ne
17F
18F
19F
15O
14O
16O
17O
18O
HCNO
13N
14N
15N
stable
12C
13C
unstable
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Hot CNO Cycle
T3108 K r 103 gm.cm-2
T1/21.7s
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
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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
18Ne(a,p)21Na
T8 6
3a flow
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12C12C
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 and 12C(12C,p)23Na channels
Major improvements expected for measurements
underground!
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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
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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
Karakas et al ApJ 643 (2006) 471
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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 AA (2007) submitted
!! new measurements underground are very much
needed !!
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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