Alex Murphy

22 May 2007 Cosener's House 1

Alex MurphyAlex Murphy

Nuclear astrophysics http://www.ph.ed.ac.uk/nuclear/Dark Matter http://hepwww.rl.ac.uk/ukdmc/ukdmc.html/

The Future of Nuclear Astrophysics in the

UK


Outline

Who we are

What we do

The Future: Three examples

Other projects/programmes

Summary


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


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


abun

danc

e

Mass number

Fe

“The 11 Greatest Unanswered Questions of Physics”National Academy of Science Report, Committee for the Physics of the Universe, 2002

“How were the elements from iron to uranium made?”

These are important questions!

Abundance curve of the elements


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?

Crab Nebula SN 1054

Artist’sconception

Chandra observation


World Context:

Europe: FAIR, REX-ISOLDE upgrade, SPIRAL-II, Eurisol US: Facility for Rare Isotope Beams Canada: ISAC-II Japan: BigRIPS China: HIRFL (Lanzhou) …

The desire to understand astrophysical phenomena is a major motivation for significant investment in new facilities around the world.

The UK has a strong track record and is well placed to play a major role in these activities


The Future: Three examples…

AIDA

TACTIC


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


AIDA: Science Case

[Fe/H] < -3.0 ‘Unique’ r-process What is its site? How does it operate?

Recent Observations of Metal Poor Stars


132Cd 48 82

R – abundances Details of nuclear properties

R-process studies

Z

N 211s

211p

231p

231d

251d

212s

211s

211p

231p

231d

251d

212s

neutrons protons

Key sources of uncertainty are the properties of highly neutron rich nuclei


GSI todayGSI today Future facilityFuture facility

FAIR


AIDA Concept

R-process nuclei implanted into multi-plane, highly segmented DSSD array Observe subsequent decays: p, 2p, p, n … 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



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/

TRIUMF Annular Chamber for Tracking and Identification of Charged particles (TACTIC)


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 -ray array Optimised for 8Li(,n) : But much much more too!

Opens up many new scientific possibilities Radical, adventurous project for UK nuclear physics


Schematic design of TACTIC detector

--

--

----

GEM readout Design: Completed


Construction:

Almost complete

In-beam testing:

Aug 2007

TACTIC: Status


Experimental Low Energy Nuclear Astrophysics (ELENA)


Direct measurements nuclear astrophysical reactions at the Gamow energy

Proposer:

The University of Edinburgh

Marialuisa Aliotta

Technical Specification:

Contact: Marialuisa Aliotta


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


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

Plymouth

London

Birmingham

Liverpool

Newcastle

Edinburgh

Inverness

Belfast

Dublin

Redcar

Hartlepool

Peterlee

Middlesbrough

Billingham

Newton Aycliffe

Stockton

Darlington

Middlesborough

Whitby

Staithes

York

Sylvanite

courtesy: S. Paling

Boulby Mine


Map of excavations

Mine Shafts

Dark Matter Research Areas

Underground science established

1km


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 ~106Salt is low in Uranium & Thorium

Virtually unlimited potential for expansion

Via mine shaft (4m lengths)+ Transport underground

JIF laboratory, CPL Support

Why is Boulby Special?


1400 1600 1800 2000 2200 2400 2600 2800 3000

1E-3

0.01

0.1

1

10

100

1000

coun

ts /h

/keV

E [keV]

Gran Sasso shielded Gran Sasso unshielded Bochum det. shiel. surface Bochum det. unshiel. surface Boulby unshielded

Advantage of salt mine: extremely low background at E < 2-3 MeV

Why is Boulby Special?

Gran Sasso

Boulby


What will be involved?

3 MV single-ended machine (e.g. NEC, Pelletron) ECR source (e.g. for high intensity (~500 A) 12C beam at high charge states) Beam-lines + detection systems (gamma, neutron, charged particles)

Ion (charge state) Particles per second

H+ 5.0x1014

He+ 5.0x1013

He2+ 1.0x1013

Xe17+ 2.9x1012

Kr15+ 4.1x1011

Ar11+ 5.6x1011

Ne6+ 1.0x1012

Fe11+ 5.7x1011 (estimated)

Ni11+ 5.7x1011 (estimated)


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


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


Not enough time to mention…


TIGRESS-SHARC

York contribution to TIGRESS Light ion transfer reactions E.g. 59,60Fe(d,p) to determine supernova (n,) rates New silicon barrel and Bragg detector


ERAWAST

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(,p), relevant to 44Ti abundance

in SNe Rate is needed to allow comparison

of -ray observation of 44Ti with core collapse models

Unique diagnostic of the collapse mechanism

Exotic Radionuclides from Accelerator Waste for Science and Technology


Ongoing programmes of research

Louvain-la-Neuve

Pioneering radioactive nuclear beams. LEDA – Pioneering large segmented Si Measuring nuclear properties relevant to

novae & XRBs


Ongoing programmes of research

TRIUMF

TUDA


Other ongoing/planned activities

Plus, unique needs of certain experiments require activity at other locations, e.g.

ANL REX-ISOLDE GANIL Orsay ORNL ANU …


Summary

ExcitingScience

New Ideas

New Scientific Opportunities

Use of Many Experimental Techniques


Extra slides







25,26Al(p,)26,27Si reactions influence predicted flux of the cosmic γ-ray

emitter 26Al


12C

13N 14N

15O14O

15N

13C

16O 17O 18O

unstable

stable

HCNO

23Mg21Mg 22Mg

25Al24Al

24Mg 25Mg

26Al

26Mg

27Al

27Si 28Si

rp-processonset

17F 18F

18Ne 20Ne19Ne

21Na 22Na20Na

19F

21Ne 22Ne

23Na

HCNO breakout

NeNacycle

(,)(p,)

(+)(p,)

(,p)

some key reactions:

14O(,p)17F

18Ne(,p)21Na

21Na(p,)22Mg

15O(,)19Ne

19Ne(p,)20Na

20Na(p,)21Mg

18F(p,)15O

26Al(p,)27Si


3 4 5 6 7 8

9 10

11 12 13

14

C (6) N (7)

O (8) F (9)

Ne (10)Na (11)

M g (12)

T1/2=1.7s

3 flow

T~3*108 K

gm.cm-2

Hot CNO Cycle

Key unknown reaction rates are dominated by resonance reactions

17F(p,Ne, 14O(p)17F, 18F(p,

Experiments require intense radioactive beams ~1 MeV/u


breakout

processing beyond CNO cycle

after breakout via:

T8 ≥ 3 15O(,)19Ne

18Ne(,p)21NaT8 ≥ 6

3 4 5 6 7 8

9 10

11 12 13

14

C (6) N (7)

O (8) F (9)

Ne (10)Na (11)

M g (12)

3 flow

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 can result in breakout from the hot CNO cycles


12C+12Cimportance: evolution of massive starsGamow region: 1 – 3 MeV min. measured E: 2.1 MeV (by -ray spectroscopy)

passive lead & concrete shielding

Major improvements expected for measurements underground!

Crab Nebula SN 1054

Aguilera et al. PRC 73 (2006) 64601

Spillane et al PRL 98 (2007) 122501

channel

p channel

12C(12C,)20Ne and 12C(12C,p)23Na channels


13C(,n)16O

Contributions from sub-threshold states?

Mainly hampered by cosmic background good case for underground investigation

importance: s-process in AGB starsGamow region: 130 - 250 keV min. measured E: 270 keV

M. Heil, PhD Thesis - Karlsruhe, 2002


Similar considerations apply also to 22Ne(,)25Mg reaction

Jaeger PRL 87 (2001) 202501

22Ne(,n)25Mgimportance: s-process in AGB starsGamow 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

Karakas et al ApJ 643 (2006) 471


Abundances of Ne, Na, Mg, Al, … in AGB stars and nova ejectaaffected by many (p,) and (p,) reactions

Iliadis et al. ApJ S134 (2001) 151; S142 (2002) 105; Izzard et al A&A (2007) submitted

!! new measurements underground are very much needed !!


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

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