High-resolution experiments on nuclear fragmentation at the FRS at GSI
M. Valentina Ricciardi
GSI Darmstadt, Germany
Outline
CHARMSCollaboration 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)
PART 1
CHARMSCollaboration for High-Accuracy experiments on nuclear
Reaction Mechanisms with magnetic Spectrometers
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 behind the CHARMS collaboration
The idea: to study spallation and fragmentation reactions in inverse
kinematics
x2, x4 Bt2, t4 velocity
flight path
x2, t2
x4, t4
beam monitor
target
scintillator
scintillator
ionisationchamber
ionisationchamber
beam
2ZΔE
A/Z from time and position:
Z from IC:
βγ
Bρ
Z
A
cm
e
0
Once mass and charge are identified (A, Z are integer numbers) the velocity is measured from B:
BZ
Ac
0m
e
Our tool: the high-resolution magnetic spectrometer FRS
Resolution:34 1052AA40Z105 ./.B/ΔB
very precise measurement
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 Z=15N=16x
con
sta
nt
see talk of P
aolo 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.
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
Measured cross sections
Measured velocities
evaporation residues
fission fragments
Example: 1 A GeV 238U on 1H
Data accuracy:
Statistic: below 3%
Systematic: 9 - 15 %
About 15,000 production cross sections and velocity distributions for spallation, fragmentation and fission products measured!
Experimental data available at: www.gsi.de/charms/data.htm
Projectile Target Energy [A GeV]56Fe 1,2H , Ti 0.3, 0.5, 0.75, 1, 1.5112,124Sn 112,124Sn 1136,124Xe 1,2H, Ti, Be, Pb 0.2, 0.5, 1
197Au 1H , Ti, Be, Au 0.5, 0.8, 1208Pb 1,2H, Ti, Be 0.5, 1238U 1,2H, Ti, Be, Pb 1 see talk of Sylvie Leray
Performed experiments
Research performed by CHARMS
Basic research:Nuclide production in fission, spallation, fragmentationStructural effects in fission and fragmentationMore on fission: dynamics, evolution of channels Nuclear EOS (momentum dependence of the mean field)Nuclear phase transitions (isospin thermometer)
Applications to other fields in physics:Fission barriers in nuclear astrophysics-resonance and quasi-elastic scattering in charge-exchange
reactions
Applications to nuclear technology:Transmutation of nuclear wasteNuclear safetyProduction of secondary beams (secondary-beam facilities)
code ABRABLA
code INCL+ABLA
Basic research:Nuclide production in fission, spallation, fragmentationStructural effects in fission and fragmentationMore on fission: dynamics, evolution of channels Nuclear EOS (momentum dependence of the mean field)Nuclear phase transitions (isospin thermometer)
Applications to other fields in physics:Fission barriers in nuclear astrophysics-resonance and quasi-elastic scattering in charge-exchange
reactions
Applications to nuclear technology:Transmutation of nuclear wasteNuclear safetyProduction of secondary beams (secondary-beam facilities)
code ABRABLA
code INCL+ABLA
PART 2
High-resolution experiments on nuclear fragmentation: two results on the properties of nuclear matter
1
Profiting of the full A, Z identification of the fragments to investigate the liquid-
gas coexistence
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?
Which signature can we expect from the liquid component?
E ~ 27 MeV A
Espectator ~ 27 MeV A
3 MeV/nucleon
Most of the nuclides belong to the plateau
E* ~ AFO
E* = length of evaporation path. The evaporation path gets shorter and shorter and shifts the initial N/Z This is our "potential"
signature
Note: the attractor line is always on the left of the stability line
Sequential evaporation: is washing out all?
attractor line
attra
ctor
line
if the final fragments fall on the attractor line every indication of the liquid-gas coexistence is lost
Yes, we can profit of the full A, Z identification to investigate the liquid-gas coexistence
This is the "footprint" of a caloric curve !
<N>/Z in full nuclear charge range
Residue corridor not reached: Residue corridor not reached: Cold residues preserve memory Cold residues preserve memory on the initial on the initial NN//ZZ over the whole Z range (high excitation energies) over the whole Z range (high excitation energies)
136Xe
124Xe
124Xe+Pb 1 A GeV 136Xe+Pb 1 A GeV
D. Henzlova
"SYMMETRY ENERGY OF FRAGMENTS PRODUCED IN MULTIFRAGMENTATION"D. Henzlova et al., arXiv nucl-ex/0507003
The isospin thermometer method
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
abrasion
break- up
evaporation
“attractor line”
experimentaldata
E*=ATFO2
E*=27A MeV
abrasionevaporation
break- up
M. V. Ricciardi
T. Enqvist
2
Profiting of the precise measurement of the velocity of the fragments
to get information on the momentum dependence of the nuclear mean field
Morrissey systematic
D. J. Morrissey, Phys. Rev. C 39 (1989) 460
124Sn +124Sn Tlab= 800 MeV/u b = 5 fmBUU calculations of mid-peripheral nucleus-nucleus collisions
L. Shi, P. Danielewicz, R. Lacey, PRC 64 (2001) 034601
The spectators response to the participant blast
Experimental evidence of the spectators response to the participant blast
M. V. Ricciardi
T. Enqvist
Fission events excluded
Velocity spectra
Fission and fragmentation can be disentangled !
see talk of P
aolo Napolitani
V. Henzl
197Au + 197Au 197Au + 27Al
1 A GeV 238U + Pb
V. HenzlT. Enqvist
C.M. momentum seems to be selectively sensitive to the momentum dependence of the nuclear force
Note: in exp b estimated only for Afrag>60
quantitative discrepancy between experiment and BUU
1 A GeV 196Au + 196Au
PART 3
Applications to nuclear technology
238U + p at 1 A GeV
Experimental data taken at the FRS at GSI
Calculation: ABRABLA code (GSI)
Prediction based on the ABRABLA and EPAX codes, GSI.
K.-H. Schmidt, 2001.
Prediction of RIB production rates at FAIR
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.
Acceleratorof electrons
Detectorsof photons and neutrons
Probingphotons
Schematic of the nuclear material detection system
Non-destructive characterisation of weapon grade materials or nuclear waste
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