Experimental Nuclear Physics Research

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Experimental Nuclear Physics Research
_at_ INP / NCSR Demokritos
INP is one of the 8 institutes of the National
Centre for Scientific Research Demokritos. It
was established in 1987 by merging the Nuclear
with the Particle Physics groups. The Nuclear
Physics group was already formed in the early
70s around a 5 MV Tandem Accelerator Lab.

• Basic Research Directions
• Nuclear Astrophysics and Reactions
• Nuclear Structure (abroad)
• Ion-Beam interactions with mater
• X-ray Physics
• Scientific Outcome (last 5 years)
• 120 papers in refereed journals
• 13 Ph.D. theses submitted,
• 1 Ph.D. in progress
• Current Scientific Personnel (7/2007)
• 6 researchers (2 in nuclear theory)
• 2 post docs, 3 Ph.D. students,
• 3 undergraduates (diploma theses)
• 3 retirements (not yet replaced )

Collaborators in Greece NTU Athens, NKU Athens,
Univ. of Ioannina, Aristotle Univ. Thessaloniki,
Univ. Crete Inst. of Material Science/NCSR
Demokritos International Collaborations
GSI, U. Cologne, U. Bochum, U. Stuttgart,
BESSY-II, TU-Berlin, JYFL, LN-Legnaro,
LNS-Catania, CSNSM-Orsay, ULB-Brussels,
CRC/Louvain-la-Neuve, OCL-Oslo,
Jozef Stefan Inst.-Ljubljana ...
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The 5.5 MV VdG Tandem Accelerator Laboratory
_at_ INP / NCSR Demokritos
The existing laboratory is the successor of a
small accelerator lab. established in 1962
around a 400 kV VdG accelerator donated by the
IAEA. The first Greek nuclear physics papers
published in 1964 came from this lab. The 5.5 MV
VdG Tandem delivered the first beams in 1974.
Sources, 300 inflector and LE tube
Tank (HV Generator)
HE tube and Analyzer magnet
Sources Sputter Duoplasmatron
Operation (no PAC)
2500 hrs/year,
65 external users
Basic Research (60)
Nuclear Astrophysics
Neutron Physics
Nuclear Reactions on light
systems Applied Research (40)
Materials, Archaeometry,
Environmental studies
Accelerated beams Source Current (max)
p 40 ?A
d 20 ?A
4He 2 ?A
Li 0.5 ?A
C 15 ?A
O 15 ?A
F 1 ?A
Ti, V, .. Os 0.5 ?A
THE ONLY ACCELERATOR FACILITY EXISTING IN GREECE
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The 5.5 MV VdG Tandem Accelerator Laboratory
_at_ INP / NCSR Demokritos
BASIC EXPERIMENTAL TOOLS
4-axis Goniometer Accuracy of 0.01o in detector
and target positioning (RBS, Channelling, NRA)
Station for analytical methods
d beam on Ti-tritiated target
En (MeV) 16 20.5 3H (d,n)4He Fn 105
n/cm2sec
Particle detectors Surface barrier detectors

?-ray detectors 4 HPGe (80, 60, 30,
20), various small-size NaI
crystals (33 and 66)
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Nuclear Astrophysics
(program launched in the early 90s)

• Until 2000
• Studies of nuclear reactions relevant to
• inhomogeneous big-bang nucleosynthesis, CNO and
  MgAl cycles.
• the group contributed to the installation of
• PAPAP 250 kV high current accelerator at
  CSNSM-Orsay, France.
• the group participated in two large Nuclear
  Astrophysics Networks
• NATO SCIENCE Network Program SC1-0065
  (1990-1993)
• NACRE Network supported by the HCP Programme
  (1995-1999)
• 1999-2001 Exp. studies of the 12C(a,?)16O
  reaction in stellar helium burning
• Realized at the Dynamitron accelerator of the
  University of Stuttgart, Germany, within a wide
• European collaboration (CSNSM, IReS, Stuttgart,
  Tübingen, Demokritos, KVI, Budapest).
• gt First implementation of a multi-detector array
  (EUROGAM) in Nuclear Astrophysics.
• since 1995 Strong collaboration with RU Bochum
  in various projects

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Nuclear Astrophysics
CONCLUSION With an overall accuracy of
4 for the absolute cross section of 13C(a,n)16O
one can subtract reliably this background in
KamLAND and thus the discovery of geo-neutrinos
appears achievable
cross section values from 0.8 to 8 MeV
with an overall accuracy of 4.
(previous accuracy 30 )
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Nuclear Astrophysics
(p-process nucleosynthesis)
Motivation Investigation of nuclear physics
uncertainties affecting the modelling of the p
process. The large discrepancies between observed
and calculated p-nuclei abundances could be the
result of unreliable cross-section
predictions. Task Systematic cross-section
measurements of proton and a-capture reactions at
sub-Coulomb energies in the Gamow window, to test
the reliability of the statistical-model
calculations at astrophysics-relevant energies.
Improve existing models of nuclear properties
entering the statistical model, i.e. Nuclear
Level Densities (NLD) and Optical Potentials
(OP). Goal Derive global (microscopic) models of
NLD and OMP for large-scale abundance
calculations. In collaboration with


Bochum (C.
Rolfs, H.W. Becker), theory group of
INP-Demokritos (P. Demetriou)
IAA/ULB (M. Arnould, S. Goriely), Stuttgart
(W. Hammer), Debrecen (E. Somorjai),
Cologne (A. Dewald) Recently
PAC-approved proposals at


JYFL (R. Julin), GANIL (F. de Oliveira Santos)
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Nuclear Astrophysics - p process
(MOTIVATION)
pathways for heavy-element nucleosynthesis p
nuclei
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Nuclear Astrophysics - p process
(MOTIVATION)
p-process reaction network
seed abundances s process
p-nuclei abundances p process
more than 20000

(?,n), (?,p), (?,?), n-, p-, ?-captures,
?-decays, e-captures
HAUSER-FESHBACH THEORY Optical Model Potentials
- Nuclear Level Densities

?-ray strength functions (32Z83 , 36N131)
NEED FOR GLOBAL MODELS OF
OMP, NLD,
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Nuclear Astrophysics - p process
(MOTIVATION)
Impact of nuclear physics uncertainties on
p-nuclei abundances
S. Goriely, ESF Workshop on p process, Vravron,
Greece, 2002, and M. Arnould and S. Goriely
Phys. Rep. 384, 1 (2003)
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Nuclear Astrophysics - p process
89Y(p,?)90Zr experiment vs. HF predictions
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Nuclear Astrophysics - p process
Proton capture reaction cross-section systematics
36 (p,?) reactions
Conclusions based on (p,?) measurements In most
cases, uncertainties affecting nuclear input
(OMP, NLD) give
rise to at most 30-40 uncertainties in the
reaction rates.
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Nuclear Astrophysics - p process
Typical (p,?) and (a,?) spectra from Ge-arrays
MINIBALL _at_ IKP/Cologne
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The 89Y(p,?)90Zr reaction cross sections from
angle-integrated ?-fluxes (the 4p ?-summing
method)
_at_ INP-Demokritos
S. Harissopulos PROCON07, Lisbon, June 17-23,
2007
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The 89Y(p,?)90Zr reaction cross sections from
angle-integrated ?-fluxes (the 4p ?-summing
method)
_at_ INP-Demokritos
_at_ DTL-Bochum
S. Harissopulos PROCON07, Lisbon, June 17-23,
2007
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The 89Y(p,?)90Zr reaction cross sections from
angle-integrated ?-fluxes (the 4p ?-summing
method)

GEANT sim.
Y
?(Y/?)(1/?)(A/NA)
sTOT (A/NA) (YTOT / ?)
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DG2 A global a-optical model potential
Nucl. Phys. A. 707, 253 (2002)
U Vc V iW ?V

• Imag. part W Woods-Saxon type
• Volume Surface (ratio, damping C)
• geometry rW, aW
• Fermi-type energy dependence
  of imaginary potential
  depth fitted
  to el. scattering reaction data at Elt 20 MeV

Correction ?V dispersive relations
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DG2 A global a-optical model potential ?
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Impact of HF uncertainties in p-process abundance
calculations
up to 2 orders of magnitude
up to 40
3-5
S. HARISSOPULOS Nuclear physics aspects of
p-process nucleosynthesis

Workshop on Level Density
and Gamma Strength in Continuum, Oslo, May 21 -
24, 2007
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Nuclear Astrophysics - p process