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!