The Underground Laboratory at Boulby: An opportunity for Nuclear ...
The Underground Laboratory at Boulby: An opportunity for Nuclear ...
The Underground Laboratory at Boulby: An opportunity for Nuclear ...
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<strong>The</strong> <strong>Underground</strong> <strong>Labor<strong>at</strong>ory</strong> <strong>at</strong> <strong>Boulby</strong>:<br />
<strong>An</strong> <strong>opportunity</strong> <strong>for</strong> <strong>Nuclear</strong> Astrophysics<br />
Marialuisa Aliotta<br />
School of Physics and Astronomy - University of Edinburgh<br />
Scottish Universities Physics Alliance<br />
<strong>Boulby</strong> mine<br />
ELENA project<br />
a virtual tour<br />
overview<br />
opportunities <strong>for</strong> NA community<br />
CANFRANC Workshop – Barcelona, 19-20 th February 2009
Scientific motiv<strong>at</strong>ion: why underground<br />
<strong>The</strong>rmonuclear Reactions in Stars<br />
take place <strong>at</strong> very low interaction energies (keV)<br />
quantum tunnelling<br />
rare processes small cross sections<br />
(10 -18 barn < σ < 10 -9 barn)<br />
<strong>The</strong>rmonuclear Reactions in the <strong>Labor<strong>at</strong>ory</strong><br />
small cross sections low yields poor signal-to-noise r<strong>at</strong>io<br />
extremely difficult to measure<br />
typical approach: measure cross section<br />
to lowest possible energies<br />
then extrapol<strong>at</strong>e
<strong>Labor<strong>at</strong>ory</strong> measurements<br />
Yield = N projectiles<br />
x N target<br />
x cross section x detection efficiency<br />
maximising the yield requires:<br />
improving “signal” (e.g. high beam currents, high target density, high efficiency)<br />
reducing “noise” (i.e. background)<br />
combin<strong>at</strong>ion of both<br />
Main Sources of Background:<br />
n<strong>at</strong>ural radioactivity (mainly U and Th)<br />
neutrons from (a,n) reactions and fission<br />
cosmic rays<br />
ideal loc<strong>at</strong>ion:<br />
underground + low concentr<strong>at</strong>ion of U and Th
<strong>The</strong><br />
<strong>Boulby</strong> Mine<br />
CANFRANC Workshop – Barcelona, 19-20 th February 2009
<strong>Boulby</strong> Mine<br />
<br />
<br />
<br />
commercial potash and salt mine<br />
Cleveland Potash Ltd<br />
deepest mine in Britain<br />
(850m to 1.3km deep)<br />
Peterlee<br />
Hartlepool<br />
Middlesborough<br />
Newton Aycliffe<br />
Redcar<br />
Inverness<br />
Darlington<br />
Billingham<br />
StocktonMiddlesbrough<br />
Staithes<br />
Edinburgh<br />
Whitby<br />
Belfast<br />
Newcastle<br />
York<br />
Dublin<br />
Liverpool<br />
Birmingham<br />
London<br />
Plymouth<br />
CANFRANC Workshop – Barcelona, 19-20 th February 2009
Proximity of services<br />
Newcastle<br />
Edinburgh<br />
Whitby<br />
York<br />
Manchester<br />
CANFRANC Workshop – Barcelona, 19-20 th February 2009
<strong>The</strong> Mine:<br />
<strong>Underground</strong> facility:<br />
roadways & cavern excav<strong>at</strong>ed<br />
in potash & rock salt layer<br />
over 40kms of tunnel dug<br />
each year (now > 1000kms in total)<br />
1000m 2 lab space, workshops, cranes,<br />
power, communic<strong>at</strong>ions, air conditioning<br />
& filtr<strong>at</strong>ion<br />
CANFRANC Workshop – Barcelona, 19-20 th February 2009
Surface facilities<br />
<strong>The</strong> John Barton Building<br />
Surface facilities<br />
~200m 2 : admin & support facility<br />
office space - computing<br />
facilities – workshop - loading<br />
bay – showers – kitchen – laundry<br />
- conference room - remote<br />
monitoring of underground<br />
courtesy: S. Paling
CPL support & services<br />
Cleveland Potash Facilities<br />
Shaft and Tunnel Maintenance<br />
Ventil<strong>at</strong>ion<br />
Health and Safety<br />
Emergency rescue<br />
Surface & <strong>Underground</strong> transport<br />
Mechanical / Electrical workshops<br />
Clean rooms<br />
Chemical handling facilities<br />
Electrical Supply
Why <strong>Boulby</strong><br />
why is <strong>Boulby</strong> ideal <strong>for</strong> <strong>Nuclear</strong> Astrophysics<br />
deep mine 1100 m (2800 m.w.e.)<br />
salt environment low in U/Th<br />
no space constraints<br />
easy access <strong>for</strong> equipment<br />
mine management support<br />
~10 6 reduction in CR<br />
+ uni<strong>for</strong>m shielding<br />
lower n- and γ-background<br />
no interference issues<br />
vertical shafts<br />
+ underground transport<br />
infrastructure & services<br />
CANFRANC Workshop – Barcelona, 19-20 th February 2009
Background comparison<br />
10000<br />
1000<br />
100<br />
γ-ray background comparison<br />
Gran Sasso<br />
<strong>Boulby</strong> surface lab<br />
surface Gran Sasso<br />
<strong>Boulby</strong><br />
counts /h/keV<br />
10<br />
1<br />
0.1<br />
0.01<br />
5-30x lower<br />
(lower U & Th)<br />
10 2 -10 3 x lower<br />
1E-3<br />
1000 2000 3000 4000 5000 6000 7000 8000<br />
E γ<br />
[keV]<br />
CANFRANC Workshop – Barcelona, 19-20 th February 2009
<strong>The</strong> Physics
key open questions<br />
f<strong>at</strong>e of massive stars (supernovae explosions)<br />
carbon burning [ 12 C+ 12 C] in advanced stages of stellar evolution<br />
Crab Nebula SN 1054<br />
where and how are heavy elements produced<br />
neutron sources [ 13 C(α,n) 16 O and 22 Ne(α,n) 26 Mg] <strong>for</strong> s-process<br />
AGB stars nucleosynthesis, Novae ejecta, Galaxy composition<br />
Ne, Na, Mg and Al nucleosynthesis [(p,γ) and (p,α) reactions]
L<strong>at</strong>e stages of stellar evolution<br />
12<br />
C+ 12 C<br />
importance:<br />
astrophysical energy:<br />
minimum measured E:<br />
evolution of massive stars<br />
1 – 3 MeV<br />
2.1 MeV (by γ-ray spectroscopy)<br />
Crab Nebula SN 1054<br />
Strieder, J. Phys. G35 (2008) 14009<br />
extrapol<strong>at</strong>ions differ by<br />
3 orders of magnitude<br />
10 18 Spillane et al.<br />
Aguilera et al.<br />
Becker et al.<br />
High and Cujec<br />
P<strong>at</strong>terson et al.<br />
10 17<br />
Jiang et al.<br />
Gasques et al.<br />
Caughlan and Fowler<br />
PA<br />
KNS<br />
large uncertainties<br />
in astrophysical models<br />
of stellar evolution<br />
and nucleosynthesis<br />
[MeV b]<br />
S * tot<br />
10 16<br />
10 15<br />
10 14<br />
1 2 3 4 5 6 7 8<br />
E cm<br />
[MeV]
wh<strong>at</strong> improvements <strong>at</strong> <strong>Boulby</strong><br />
exploit lower γ-ray background γ-ray measurements<br />
12 C+ 12 C p + 23 Na * 23 Na + γ E γ = 440 keV<br />
α + 20 Ne * 20 Ne + γ<br />
E γ = 1.63 MeV<br />
expected background <strong>at</strong> least 100x lower than on surface<br />
lowest energy achievable E cm<br />
~1.5 MeV<br />
gre<strong>at</strong>ly improved precision (~ 10-15%, i.e. 10x lower than present)<br />
astrophysical impact<br />
constrain/discrimin<strong>at</strong>e between extrapol<strong>at</strong>ions<br />
determine ignition temper<strong>at</strong>ure <strong>for</strong> 12 C+ 12 C fusion<br />
show if lower-mass stars end up as supernovae<br />
solve current discrepancy on mass estim<strong>at</strong>es of SN progenitors
Neutron sources <strong>for</strong> heavy elements<br />
13<br />
C(α,n) 16 O<br />
importance:<br />
neutron source <strong>for</strong> s-process in AGB stars<br />
astrophysical energies: 130 - 250 keV<br />
minimum measured E: 270 keV<br />
(s-process = slow neutron-capture <strong>for</strong> heavy elements nucleosynthesis)<br />
current st<strong>at</strong>us<br />
improvements <strong>at</strong> <strong>Boulby</strong><br />
neutron detection<br />
expected n-background ~ 50x lower<br />
lowest energy achievable E cm ~200 keV<br />
gre<strong>at</strong>ly improved precision (~15%)<br />
astrophysical impact<br />
neutron density <strong>for</strong> s-process<br />
nucleosynthesis p<strong>at</strong>hs & abundances<br />
options <strong>for</strong> improvements of surface measurements: exhausted
Neutron sources <strong>for</strong> heavy elements<br />
22<br />
Ne(α,n) 25 Mg<br />
current st<strong>at</strong>us<br />
importance:<br />
astrophysical energies:<br />
minimum measured E:<br />
s-process in AGB stars<br />
400 - 700 keV<br />
~550 keV<br />
improvements <strong>at</strong> <strong>Boulby</strong><br />
neutron detection<br />
upper limits<br />
increased sensitivity ~ 100x<br />
lowest energy achievable E cm ~ 537 keV<br />
gre<strong>at</strong>ly improved precision (~ 15%)<br />
astrophysical implic<strong>at</strong>ions<br />
alter nucleosynthesis p<strong>at</strong>hs<br />
change elemental abundances<br />
options <strong>for</strong> improvements of surface measurements: exhausted
Other examples<br />
abundances of Ne, Na, Mg, Al, … in AGB stars and nova ejecta<br />
affected by many (p,γ) and (p,α) reactions<br />
shaded areas indic<strong>at</strong>e order of magnitude(s) uncertainties<br />
Iliadis et al. ApJ S134 (2001) 151; S142 (2002) 105; Izzard et al A&A (2007)<br />
!! underground measurements are necessary !!
AGB Stars’ nucleosynthesis<br />
Current Uncertainties<br />
r<strong>at</strong>e change implic<strong>at</strong>ions:<br />
conversion of 22 Ne to 23 Na (up to a factor ~40)<br />
factor 2 uncertainty in 26 Al abundance<br />
20% vari<strong>at</strong>ion in abundances of most isotopes
<strong>The</strong> Project<br />
Experimental Low-Energy <strong>Nuclear</strong> Astrophysics<br />
European <strong>Labor<strong>at</strong>ory</strong> <strong>for</strong> Experimental <strong>Nuclear</strong> Astrophysics<br />
CANFRANC Workshop – Barcelona, 19-20 th February 2009
Overview<br />
<strong>The</strong> ELENA Project<br />
Stage I: Feasibility Study & Design<br />
(dur<strong>at</strong>ion: 24 months, cost: £410k)<br />
neutron & γ-ray background measurements <strong>at</strong> <strong>Boulby</strong><br />
infrastructure design (by engineering company)<br />
acceler<strong>at</strong>or and beam tests<br />
Stage II: Construction, Commissioning, Exploit<strong>at</strong>ion<br />
(dur<strong>at</strong>ion: ~24 months (C,C) + 60 months (E); cost: ~ £6M)<br />
construction of labor<strong>at</strong>ory infrastructure<br />
commissioning of acceler<strong>at</strong>or + ion source facility<br />
initial scientific exploit<strong>at</strong>ion (5 years)
ELENA - Stage I<br />
Feasibility Study and Design<br />
PI: Marialuisa Aliotta* University of Edinburgh UK<br />
Co-I: Wilfried Galster* University of Str<strong>at</strong>hclyde UK<br />
Co-I: Sean Paling $ University of Sheffield UK<br />
Frank Strieder* $ Ruhr-Universität Bochum Germany<br />
Lucio Gialanella* INFN, Naples Italy<br />
Cristina Bordeanu* HH-NIPNE<br />
Romania<br />
Nigel Smith $ Ruther<strong>for</strong>d Appleton Lab UK<br />
David Pybus Cleveland Potash Ltd, <strong>Boulby</strong> UK<br />
PDRA* $ University of Edinburgh UK<br />
(*) expertise in <strong>Nuclear</strong> Astrophysics<br />
($) expertise in <strong>Underground</strong> Science<br />
+ strong support from RAL & CPL
Work Breakdown Structure<br />
ELENA-I Workpackages<br />
WP1: Background measurements<br />
WP2: Acceler<strong>at</strong>or & ion source tests<br />
WP3: Scientific equipment & requirements<br />
WP4: <strong>Labor<strong>at</strong>ory</strong> design<br />
WP5: Health & Safety<br />
identific<strong>at</strong>ion of site <strong>for</strong> infrastructure<br />
Overall Objectives<br />
acceler<strong>at</strong>or specific<strong>at</strong>ions<br />
experimental requirements<br />
labor<strong>at</strong>ory design and specific<strong>at</strong>ions<br />
total cost and timescale estim<strong>at</strong>es<br />
Intern<strong>at</strong>ional Workshop to establish financial/scientific contributions<br />
to “ELENA – Stage II” from (inter)n<strong>at</strong>ional NA community
Wh<strong>at</strong> facility<br />
the acceler<strong>at</strong>or<br />
expected beams currents<br />
Ion (charge st<strong>at</strong>e)<br />
Particles per second<br />
H +<br />
He + 5.0x10 14<br />
5.0x10 13<br />
Xe 17+ 2.9x10 12<br />
Kr 15+ 4.1x10 11<br />
Ar 11+ 5.6x10 11<br />
Ne 6+ 1.0x10 12<br />
Fe 11+ 5.7x10 11 (estim<strong>at</strong>ed)<br />
Ni 11+<br />
5.7x10 11 (estim<strong>at</strong>ed)<br />
3 MV single-ended machine (e.g. Pelletron by NEC)<br />
ECR source (e.g. <strong>for</strong> high intensity (~500 µA) 12 C beam <strong>at</strong> high charge st<strong>at</strong>es)<br />
Beam-lines + detection systems (gamma, neutron, charged particles)<br />
allow <strong>for</strong> measurements over extended energy range<br />
studies possible both in direct and inverse kinem<strong>at</strong>ics
Current St<strong>at</strong>us<br />
Proposal <strong>for</strong> ELENA – Stage I submitted to STFC in December 2008<br />
Very positive Referees’ reports<br />
Present<strong>at</strong>ion made to STFC PPRP Panel meeting on February 4 th 2009<br />
STFC Executive meeting on Thursday, February 19 th 2009<br />
decision on funding expected soon<br />
Opportunities <strong>for</strong> <strong>Nuclear</strong> Astrophysics community<br />
unique facility worldwide<br />
complement & extend beyond current capabilities <strong>at</strong> LUNA<br />
further strengthen Europe’s leadership in the field
Contact: m.aliotta@ed.ac.uk
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