1. M. Valentina Ricciardi GSI Darmstadt, Germany New London, June 15-20, 2008 Fragmentation Reactions: Recent Achievements and Future Perspective

2. Motivation and Outlook I. Recall old results and features of fragmentation reactions Initial motivations: Radioactive-ion-beams production Astrophysics Many data were measured in the last decades: the major features of fragmentation products were determined in the past II. Recent achievements How recent experimental results confirm (or not) the validity of our picture How recent results can be exploited for fundamental physics or applications Recent results brought new important motivations to study fragmentation. III. How is the future of fragmentation?

3. impact parameter fragmentation / spallation multifragmentation vaporisation (fireball) deep-inelastic transfer incomplete fusion multifragmentation multifragmentation High-energy nucleus-nucleus reactions impinging energy P R O D U C T I O N O F R I B s 40 A MeV 1 A GeV

4. Collision: removal of nucleons in quasi-free nucleon-nucleon collisions. Thermalisation: formation of a compound nucleus Deexcitation: Highly excited fragments loose additional mass and cool down. Cold residual nucleus: Gamma decay and structural effects came into the game Experimental observables indicate the existence of these sequential stages fast slow de-excitation cold fragment thermalisation collision Understanding of fragmentation reactions

5. Fragmentation reactions Data: Courtesy of ALADIN, GSI Z of the 2 nd heaviest fragment 197 Au + 197 Au at 1 A GeV V. Henzl, PhD Thesis (Univ. Prague, Czech Republic, 2006) Z of the heaviest fragment 197 Au + 197 Au at 1 A GeV

6. Main features of fragmentation reactions Mass yields – dependence on available energy asymptotic behavior

7. evaporation attractor line N/Z of the final fragments Main features of fragmentation reactions R. J. Charity, PRC 58 (1998)

8. systematic behavior D. J. Morrissey, Phys. Rev. C 39 (1989) 460 Kinematical features Main features of fragmentation reactions D. E. Greiner et al., PRL 35 (1975) 152 10 Be 2.1 A GeV 12 C + Be R. Pfaff et al., Phys. Rev. C 51 (1995) 1348 Morrissey's systematic

9. Previous understanding of fragmentation reactions Asymptotic behaviors: in mass distributions in N/Z (attractor line) Systematics in kinematics ( D. J. Morrissey, Phys. Rev. C 39 (1989) 460 ) The idea behind limiting fragmentation and in the semi-empirical code EPAX (K. Sümmerer and B. Blank, PRC 61 (2000) 034607 NIM B 204 (2003) 278 ) Can we confirm this nowadays? J. Hüfner, Phys. Reports 125, 1985 "Can we expect a simple description of a complicated process like fragmentation? I think yes. A simple description works because the process is extremely complicated and phase space dominates over dynamics."

10. Recent achievements What did come up in the last years? Use of high resolution magnetic spectrometers: - Full isotopic identification of the reaction residues over the whole mass range - High precision velocity measurements MARS recoil separator at Texas A&M University (Fermi energies) A1900 fragment separator at MSU, East Lansing (above Fermi energies) FRS magnetic spectrometer at GSI, Darmstadt (relativistic energies)

11. Very precise production cross-sections on the entire production range Beautiful data 136,124 Xe on Pb at 1 A GeV D. Henzlova, submitted to PRC 58,64 Ni on Be at 140 A MeV M. Mocko et al., Phys. Rev. C 74 (2006) 054612 ISOSCALING (dedicated talks)

12. Memory of the past Westfall (1979), Porile (1964), Ku (1977), J. Reinhold et al., PRC 58 (1998) 247 R. Pfaff et al., PRC 53 (1996) 1753 78 Kr on Ni at 75 A MeV

13. evaporation corridor not reached D. Henzlova et al., submitted to PRC Memory of the past cold residues preserve memory on the initial N/Z over the whole nuclear charge range  1 A GeV 238 U on Pb  1 A GeV 238 U on Ti K.-H. Schmidt et al., NPA 710 (2002) 157

14. Isospin thermometer The "memory effect" can be explained if break-up is included The temperature can be measured by tracing back evaporation K.-H. Schmidt et al., NPA 710 (2002) 157

15. superfluid liquid coexistence gas E/MeV 5 7010300 A  25 0.5 T/MeV Nuclear superfluidity: it vanishes at about E*~10 MeV  valid only for low-energy-reaction residues Footprints of a superfluid

16. A. M. Poskanzer et al., Phys. Rev. C 3 (1971) 882 C. N. Knott et al., Phys. Rev. C 53 (1996) 347 5500 MeV protons on 238 U + protons Footprints of a superfluid C. Zeitlin et al., PRC 77 (2008) 034605

17. Footprints of a superfluid 1 A  GeV 238 U  Ti Even-odd fluctuations are produced at the end of the evaporation cascade  Structural effects are restored in the end products of hot decaying nuclei (transition from normal liquid to superfluid)  For heavy fragments gamma emission becomes competitive to particle decay Yields from highly excited nuclei reflect the transition from liquid to superfluid M. V. Ricciardi, Nucl. Phys. A 733 (2004) 299 ● N=Z ■ N=Z+2 ▲ N=Z+4  N=Z+6 ● N=Z+1 ■ N=Z+3 ▲ N=Z+5

18. cold fragmentation A. Stolz et al., PRC 65 (2002) 064603 J. Benlliure et al., NPA 660 (1999) 87 M. De Jong et al., NPA 628 (1998) 479 K.H. Schmidt et al., NPA 542 (1992) 699 Exploiting the large statistical fluctuations in N/Z two-step scheme (dedicated talk) Radioactive Ion Beams Measuring neutron separation energies far from stability W. A. Friedmann, M. B. Tsang, PRC 67 (2003)

19. Exploiting the production cross sections of n-rich nuclei Mocko et al., EPL 79 (2007) 12001 M. B. Tsang et al., Phys. Rev. C 76, 067601 (2007) exponential dependence determination of nuclear binding energies

20. Morrissey systematic indicates: - a "slowing down" for small mass losses, attributed to friction - a chaotic behavior for large mass-losses Mean longitudinal velocity Morrissey systematics D. J. Morrissey, Phys. Rev. C 39 (1989) 460 Experimental evidence of the effects of the participants on the spectators M. V. Ricciardi et al., PRL 90 (2003) 212302 Theoretical prediction: "Spectator response to the participant blast" L. Shi, P. Danielewicz, R. Lacey Phys. Rev. C 64 (2001) 034601

21. V. Henzl, PhD thesis, University of Prague, 2006 Mean longitudinal velocity M. Notani et al., PRC 76 (2007) 044605

22. Mean longitudinal velocity A. Bacquias, PhD thesis, University of Strasbourg, 2008 Friction in abrasion: can we learn something about in-medium nucleon-nucleon cross sections? work in progress !

23. Longitudinal momentum width A. Bacquias, PhD thesis, University of Strasbourg, 2008 Morrissey analytical formula The effects of abrasion + break-up + coulomb expansion + evaporation are considered

24. Future perspectives

25. Measure: A, Z Fission fragments n, p, gammas velocity R3B @FAIR - Germany Exclusive experiments AND high resolution

26. Accurate and extensive data show that systematic and asymptotic behaviors are not respected Our understanding of the fragmentation process had to be revisited Three different phases can be accessed by fragmentation reactions Dynamical effects (in the collision?) are visible Important fundamental physical issues can be studied with fragmentation reactions Fragmentation reactions: a path through phase-transitions where dynamical effects are important Conclusion and Discussion