Highresolution experiments on nuclear fragmentation at the FRS at GSI

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High-resolution experiments on nuclear
fragmentation at the FRS at GSI M. Valentina
Ricciardi GSI Darmstadt, Germany
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Outline
CHARMS Collaboration for High-Accuracy
experiments on nuclear Reaction
Mechanisms with magnetic Spectrometers (15 min)
High-resolution experiments on nuclear
fragmentation two results on
properties of nuclear matter (15min)
Applications to nuclear technology (5min)
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PART 1 CHARMS Collaboration for High-Accuracy
experiments on nuclear Reaction
Mechanisms with magnetic Spectrometers
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The idea behind the CHARMS collaboration
Collaboration for High-Accuracy experiments on
nuclear Reaction Mechanisms with magnetic
Spectrometers At GSI, Darmstadt, availability
of - ion beams at relativistic energy (SIS) -
high-resolution magnetic spectrometer (FRS)
The idea to study spallation and fragmentation
reactions in inverse kinematics
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Our tool the high-resolution magnetic
spectrometer FRS
Z from IC
A/Z from time and position
Once mass and charge are identified (A, Z are
integer numbers) the velocity is measured from
B?
very precise measurement
Resolution
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The high-quality experimental outcomes
- full identification (A, Z) ? extremely precise
production cross-sections - absolute velocity
from B? ? extremely precise velocity spectra
136Xe(1 A GeV)Pb
Z15 N16
x constant
see talk of Paolo Napolitani

• Limited acceptance
• in magnetic rigidity combine several B?
  settings to cover all A/Z and velocities
• in angle only a part of the real production is
  measured.

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Example 1 A GeV 238U on 1H
Measured velocities
Measured cross sections
evaporation residues
fission fragments
Taïeb et al., NPA 724 (2003) 413 Ricciardi et al,
PRC 73 (2006) 014607 Bernas et al., NPA 765
(2006) 197 Bernas et al., NPA 725 (2003) 213
Armbruster et al., PRL 93 (2004) 212701
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Performed experiments
see talk of Sylvie Leray
About 15,000 production cross sections and
velocity distributions for spallation,
fragmentation and fission products measured!

• Data accuracy
• Statistic below 3
• Systematic 9 - 15

Experimental data available at
www.gsi.de/charms/data.htm
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Research performed by CHARMS
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PART 2 High-resolution experiments on nuclear
fragmentation two results on
the properties of nuclear matter
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1 Profiting of the full A, Z identification of
the fragments to
investigate the liquid-gas coexistence
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Evidence of phase-transition from the caloric
curve
Evidence based on the yields of very light
isotopes
Is there some
equivalent signature in heavy residues?
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Which signature can we expect from the liquid
component?
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Sequential evaporation is washing out all?
attractor line
attractor line
Note the attractor line is always on the left of
the stability line
? if the final fragments fall on the attractor
line every indication of the liquid-gas
coexistence is lost
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Yes, we can profit of the full A, Z
identification to
investigate the liquid-gas coexistence
This is the "footprint" of a caloric curve !
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ltNgt/Z in full nuclear charge range
136Xe

• 136XePb 1 A GeV

• 124XePb 1 A GeV

124Xe
D. Henzlova
Residue corridor not reached Cold residues
preserve memory on the initial N/Z over the whole
Z range (high excitation energies)
"SYMMETRY ENERGY OF FRAGMENTS PRODUCED IN
MULTIFRAGMENTATION"D. Henzlova et al., arXiv
nucl-ex/0507003
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The isospin thermometer method
M. V. Ricciardi T. Enqvist
The idea the mean N/Z-ratio of the final
elements can be used in combination with
statistical-model codes in order to deduce the
freeze-out temperature after break up
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2 Profiting of the precise measurement
of the velocity of the fragments
to get information on the momentum
dependence of the nuclear mean field
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Morrissey systematic
D. J. Morrissey, Phys. Rev. C 39 (1989) 460
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The spectators response to the participant blast
124Sn 124Sn Tlab 800 MeV/u b 5
fm BUU calculations of mid-peripheral
nucleus-nucleus collisions L. Shi, P.
Danielewicz, R. Lacey, PRC 64 (2001) 034601
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Experimental evidence of the spectators response
to the participant blast
Fission events excluded
M. V. Ricciardi T. Enqvist
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Velocity spectra
see talk of Paolo Napolitani
Fission and fragmentation can be disentangled !
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197Au 197Au 197Au 27Al
V. Henzl
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1 A GeV 238U Pb
T. Enqvist
V. Henzl
C.M. momentum seems to be selectively sensitive
to the momentum dependence of the nuclear force
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1 A GeV 196Au 196Au
quantitative discrepancy between experiment and
BUU
Note in exp ?b? estimated only for Afraggt60
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PART 3 Applications to nuclear technology
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238U p at 1 A GeV
Experimental data taken at the FRS at
GSI Calculation ABRABLA code (GSI)
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Prediction of RIB production rates at FAIR
Prediction based on the ABRABLA and EPAX codes,
GSI. K.-H. Schmidt, 2001.
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Non-destructive characterisation of weapon grade
materials or nuclear waste
D. Ridikas et al. 2004
Detection sensitivity. 0.1 g of nuclear material
per ton of container
Needed delayed-neutron yields, fission fragments
A and Z distributions.
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Conclusions
The CHARMS group and collaboration fission,
spallation and fragmentation reactions at
relativistic energies www.gsi.de/charms Ion beams
High-resolution magnetic spectrometer ?
two observables production cross sections
for all nuclei and velocity spectra Examples of
research
Fragmentation cross sections of heavy
fragments can give indication on the liquid-gas
phase transition Velocity
of fragmentation residues as an observable to
study the nuclear mean field The longitudinal
momentum is measurable with the required
precision with high-resolution magnetic
spectrometers RIB, Nuclear safety, nuclear waste
and other potential applications