Projectile Projectile Fragmentation at Fragmentation at
the Fragment the Fragment SeparatorSeparator
Andreas HeinzAndreas HeinzWright Nuclear Structure Laboratory, Wright Nuclear Structure Laboratory,
Yale UniversityYale University
for the for the CHARMSCHARMS CollaborationCollaboration
Symposium on 30 Years of Projectile Fragmentation, ACS meeting, San Francisco, September 10-11, 2006
CHARMSCHARMSCCollaboration for ollaboration for HHigh-igh-AAccuracy Experiments on Nuclear ccuracy Experiments on Nuclear RReaction eaction
MMechanisms with Magnetic echanisms with Magnetic SSpectrometerspectrometersP. ArmbrusterP. Armbruster11, A. , A. BacquiasBacquias11, , L. GiotL. Giot11, V. Henzl, V. Henzl1,121,12, D. Henzlova, D. Henzlova1,121,12, A. Keli, A. Kelićć11, S. , S. LukićLukić11, , R. R.
PleskaPleskačč11, M.V. Ricciardi, M.V. Ricciardi11, , K.-H. SchmidtK.-H. Schmidt11, O. Yordanov, O. Yordanov11, J. Benlliure, J. Benlliure22, J. Pereira, J. Pereira2,122,12, E. Casarejos, E. Casarejos22, , M. FernandezM. Fernandez22, T. Kurtukian, T. Kurtukian22, C.-O. Bacri, C.-O. Bacri33, M. Bernas, M. Bernas33, L. Tassan-Got, L. Tassan-Got33, L. Audouin, L. Audouin33, C. St, C. Stééphanphan33, ,
A. BoudardA. Boudard44, S. Leray, S. Leray44, C. Volant, C. Volant44, C. Villagrasa, C. Villagrasa44, B. Fernandez, B. Fernandez44, J.-E. Ducret, J.-E. Ducret44, J. Ta, J. Taïïebeb55, C. , C. SchmittSchmitt66, B. Jurado, B. Jurado77, F. Reymund, F. Reymund88, P. Napolitani, P. Napolitani88, D. Boilley, D. Boilley88, A. Junghans, A. Junghans99, A. Wagner, A. Wagner99, A. , A.
KuglerKugler1010, V. Wagner, V. Wagner1010, A. Krasa, A. Krasa1010, A. Heinz, A. Heinz1111, P. Danielewicz, P. Danielewicz1212, L. Shi, L. Shi1212, T. Enqvist, T. Enqvist1313, K. , K. HelariuttaHelariutta1414, A. Ignatyuk, A. Ignatyuk1515, A. Botvina, A. Botvina1616
11GSI, Darmstadt, GermanyGSI, Darmstadt, Germany22Univ. Santiago de Compostela, Sant. de Compostela, SpainUniv. Santiago de Compostela, Sant. de Compostela, Spain
33IPN Orsay, Orsay, FranceIPN Orsay, Orsay, France44DAPNIA/SPhN, CEA Saclay, Gif sur Yvette, FranceDAPNIA/SPhN, CEA Saclay, Gif sur Yvette, France
55DEN/DMS2S/SERMA/LENR, CEA Saclay, Gif sur Yvette , FranceDEN/DMS2S/SERMA/LENR, CEA Saclay, Gif sur Yvette , France66IPNL, Universite Lyon, Groupe Materie Nucleaire 4, Villeurbanne, FranceIPNL, Universite Lyon, Groupe Materie Nucleaire 4, Villeurbanne, France
77CENBG, Bordeau-Gradignan, FranceCENBG, Bordeau-Gradignan, France88GANIL, Caen FranceGANIL, Caen France
99Forschungszentrum Rossendorf, Dresden, GermanyForschungszentrum Rossendorf, Dresden, Germany1010Nuclear Physics Institute, Rez, Czech RepublicNuclear Physics Institute, Rez, Czech Republic
1111Wright Nuclear Structure Laboratory, Yale University, New Haven, USAWright Nuclear Structure Laboratory, Yale University, New Haven, USA1212NSCL and Physics and Astronomy Department, Michigan State University, East Lansing, USANSCL and Physics and Astronomy Department, Michigan State University, East Lansing, USA
1313CUPP Project, Pyhasalmi, FinlandCUPP Project, Pyhasalmi, Finland1414Univeristy of Helsinki, Helsinki, FinlandUniveristy of Helsinki, Helsinki, Finland
1515IPPE Obninsk, RussiaIPPE Obninsk, Russia1616Institute for Nuclear Research, Russian Academy of Sciences, Moscow, RussiaInstitute for Nuclear Research, Russian Academy of Sciences, Moscow, Russia
TopicsTopics
Basic researchBasic research:: Momentum dependence of the nuclear mean field (Talk of Momentum dependence of the nuclear mean field (Talk of
V. Henzl)V. Henzl) Thermal instabilities of nuclear matter (Talk of D. Thermal instabilities of nuclear matter (Talk of D.
Henzlova)Henzlova) Dissipation in Nuclear Matter Dissipation in Nuclear Matter Very asymmetric fissionVery asymmetric fission Structure effects in fission and fragmentationStructure effects in fission and fragmentation Nuclide production in fragmentation and fission (Talk of J. Nuclide production in fragmentation and fission (Talk of J.
Benlliure)Benlliure)
ApplicationsApplications:: Nuclear astrophysicsNuclear astrophysics Spin, alignment and polarisation in fragmentationSpin, alignment and polarisation in fragmentation Transmutation of nuclear wasteTransmutation of nuclear waste Nuclear safetyNuclear safety Production of secondary beams (RIA, FAIR)Production of secondary beams (RIA, FAIR)
The Heavy-Ion Synchrotron at The Heavy-Ion Synchrotron at GSIGSI
Beams from p to 238U Energies of 1-2 A GeV
The FRagment Separator FRSThe FRagment Separator FRS
Z / Z 200
A / A 400
()/ 5·10-4
M.V. Ricciardi, PhD thesis
238U+Ti at 1 A GeV
Two “natural” observables:
Momentum distributions
Cross sections
Projectile FragmentationProjectile FragmentationTwo different time scales for abrasion and ablation →
(at least) a two-step process!
Abrasion
Ablation
Abrasion of nucleons in a peripheral collision produces excited CN Abrasion of nucleons in a peripheral collision produces excited CN (prefragment).(prefragment). high <E*> high <E*> 27 MeV per abraded nucleon 27 MeV per abraded nucleon
De-excitation through particle evaporation (n,p,De-excitation through particle evaporation (n,p,) or fission) or fission (relatively) low angular momenta (relatively) low angular momenta (listen tomorrow to Z. Podolyak)(listen tomorrow to Z. Podolyak)
Break-up
Momentum DistributionsMomentum DistributionsBi208-193
83
A. Kelić et al., PRC 70, 064608 (2004)
Two components can be distinguished:- Quasi-elastic scattering (p replaces n in 208Pb)- (1232) excitation (e.g. n 0 p + -)Probability for excitation and energy in the nuclear medium can be deduced.
Nucleon excitation in projectile fragmentation1H(208Pb,208Bi)x at 1 A GeV
2H(208Pb,208Bi)x at 1 A GeV
Velocity of 208Bi in the frame of the 208Pb projectile.
Measured Nuclide Production in Measured Nuclide Production in Fragmentation and In-flight FissionFragmentation and In-flight Fission
Excellent basis for model developmentData available at: http://www-w2k.gsi.de/charms/data.htm
For heavy projectile fission opens up as a decay channel → knowledge of the fission properties of unstable heavy nuclei is necessary
ExperimentExperiment
Charge distribution
Total Kinetic Energy (TKE) distribution
Two Reaction Two Reaction MechanismsMechanisms
Plastic: only nuclear-induced fission
Pb: nuclear and electromagnetic-induced fission
Nuclear: ZCN = Z1 + Z2
Electromagnetic: ZCN = Z1 + Z2
→ trigger for low excitation energies!
Experimental Information Experimental Information on Fission at low Eon Fission at low E**
E*-Bf < 10 MeV
E. Konecny et al., Proc. Third IAEA Symp. Phys. Chem. Fission Vol 2, 1974, p. 3
A lot of new data!
Transition from Symmetric Transition from Symmetric to Asymmetric Fissionto Asymmetric Fission
Data resulted in:
o improved models for yield calculations
o better understanding of low-energy fission: evolution of fission channels, influence of pairing, …
GSI code ABLA - Examples low-energy GSI code ABLA - Examples low-energy reactionsreactions
Excitation function and A- and Z- distributions:
Dissipation Dissipation and Nuclide and Nuclide Production Production
J. Taïeb et al.
Collective motion converts into “heat” due to friction
Potential difference
Junior researcher
Dissipation and Nuclear Dissipation and Nuclear FissionFission
What does this have to do with nuclear fission?
Collective motion
Deformation
Energy
Compound Nucleus
Saddle point
Scission
Ground state
τCN-Saddle
τSaddle-Scission
Fiss
ion
barr
ier
Dissipation and the Dissipation and the Saddle Point Saddle Point TemperatureTemperature
Deformation
En
er
gy
Compound Nucleus
Saddle point
Ground state
τCN-Saddle
τSaddle-Scission
ΔE
Reminder: the connection between temperature and excitation energy
a
ETnuc
*
Level density parameter
If there is any dissipation τneutron < τfission → mneutron and ΔE get larger
→ Tsaddle is smaller
Charge Width as a Charge Width as a ThermometerThermometer
Asymmetric mass splitSymmetric mass
splitAsymmetric mass split
From: Bjornholm, Lynn; Rev. Mod. Phys. 52, 725 (1980)
Mass asymmetry η
Pote
nti
al Populatio
n
2
2
2
2
2
fissA
saddle
fiss
fissZ
dVd
T
A
Z
238U @ 1 A GeV on 9Be
First Results
Model description fails for deformed projectiles
→ influence of “initial” deformation on dissipation in nuclear fission
Spherical
Deformed
Caution when interpreting nuclide yields with thermodynamic approaches without nuclear structure!
Fine structure in residue yields after violent nuclear
collisions
M.V. Ricciardi et al., NPA 733, 299 (2004)
GSI code ABLA – Examples for high-GSI code ABLA – Examples for high-energy reactionsenergy reactions
Experiment
Calculation
The Future: RThe Future: R33BB
Measure:
Charge AND Mass of projectile and fission fragments
Neutrons
Gammas
Cross sections
Exclusive experiments AND high resolution
Future (Part II): Electron-Ion Future (Part II): Electron-Ion scattering in a Storage Ring (eA scattering in a Storage Ring (eA
Collider) Collider) ELISeELISe• 125-500 MeV electrons • 200-740 MeV/u RIBs
• achievable luminosity: 1025-1029 cm-2s-1 depending on ion species
- spectrometer setup at the interaction zone
- detection system for RI in the arcs of the NESR (see EXL)
ConclusionsConclusions A lot of progress in the understanding of projectile A lot of progress in the understanding of projectile
fragmentation.fragmentation. Heavy beams and high resolution spectrometers are Heavy beams and high resolution spectrometers are
excellent tools.excellent tools. Don’t forget the influence of nuclear structure and Don’t forget the influence of nuclear structure and
nucleonic exciations.nucleonic exciations. A wealth of new data from projectile fragmentation, A wealth of new data from projectile fragmentation,
spallation, in-flight fission and fission of secondary spallation, in-flight fission and fission of secondary beams allowed for the development of realistic beams allowed for the development of realistic models with predictive power.models with predictive power.
Applications in accelerator driven systems, nuclear Applications in accelerator driven systems, nuclear astrophysics, ...astrophysics, ...
The future looks bright!The future looks bright!
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