Entry distributions for fragments produced in deep-inelastic collisions with stable and radioactive beams For the PARIS collaboration W. Królas, M. Kmiecik, P. Bednarczyk, B. Fornal, A. Maj, M. Ciemała, M. Ziębliński Institute of Nuclear Physics PAN, Kraków, Poland F. Crespi, A. Bracco, S. Leoni, F. Camera, G. Benzoni, O. Wieland, B. Million University of Milano and INFN, Italy F. Azaiez, J. Wilson, IPN Orsay, France Ch. Schmitt, GANIL, O. Dorvaux, IPHC Strasbourg We propose to study the entry distributions in angular momentum and excitation energy plane for fragments produced in deep-inelastic collisions as a function of energy, mass and isospin asymmetry of the colliding ions The PARIS multidetector array made of LaBr3-NaI phoswich scintillators will be used for high efficiency measurements of the sum energy and multiplicity of  rays emitted from the fragments PARIS can be coupled to a magnetic spectrometer for isotopic identification of fragments or to the Recoil Filter Detector for selection of products of binary reactions W. Królas , IFJ PAN @ 2nd SPES Workshop, Legnaro, May 2014

final fragment entry region Entry distributions (I) In compound nucleus reactions: In quasi-elastic reactions: selective population of relatively low spin states For fragments produced in DIC a long distribution of high-spin states observed in gamma-ray spectroscopy experiments Full understanding of the entry distribution in angular momentum and excitation energy for fragments produced in DIC is missing, even though this aspect is very important for application to spectroscopy A possible dependence of the entry distribution on the mass and isospin asymmetry of the colliding system is of special interest spin excitation energy Yrast line discrete transitions particle emission g transitions statistical primary entry region final fragment entry region Sn spin Since the limits of stability in spin and excitation energy are defined by the fission barrier it may well be that the entry distribution for fragments produced in collisions involving exotic, very neutron rich isotopes, differ from those of stable systems. W. Królas , IFJ PAN @ 2nd SPES Workshop, Legnaro, May 2014

Entry distributions (II) The entry distributions are sensitive to small entrance channel effects as demonstrated for reaction leading to formation of heaviest Z > 100 nuclei: Strong effect in the entry distribution observed for a slight adjustment in the reaction energy 208Pb(48Ca, 2n)254Nb ELAB = 215 MeV ELAB = 219 MeV Since the limits of stability in spin and excitation energy are defined by the fission barrier it may well be that the entry distribution for fragments produced in collisions involving exotic, very neutron rich isotopes, differ from those of stable systems. P. Reiter et al., Phys. Rev. Lett. 84, 2542 (2000) GAMMASPHERE & FMA measurement, 101 single Ge detectors used for sum energy and multiplicity W. Królas , IFJ PAN @ 2nd SPES Workshop, Legnaro, May 2014

PARIS4SPES Detectors (I) The 2p PARIS array (2017) will be composed of 12 clusters of 108 phoswich detectors Each cluster is 3 x 3 phoswich detectors Each phoswich is 2”x2”x2” LaBr3 coupled to 2”x2”x6” NaI(Tl) coupled to a common photomultiplier High overall efficiency, also for high energy gamma-rays Good energy resolution of ~2% Very good timing characteristics High granularity Modular design Best instrument to measure sum energy vs. multipilicity with one set of detectors W. Królas , IFJ PAN @ 2nd SPES Workshop, Legnaro, May 2014

PARIS4SPES coupled to … Detectors (II) The PRISMA spectrometer Large solid angle magnetic spectrometer based on trajectory reconstruction, full identification of fragments The GALILEO Ge detectors and the Recoil Filter Detector (RFD) Fragment tagging with RFD will lack isotopic ID but will have larger solid angle / efficiency Possible g gating to select narrow parts of population Will allow to select specific fragments populated in the reaction at different collision energies GALILEO RFD PRISMA (optionally VAMOS at GANIL) 2p PARIS W. Królas , IFJ PAN @ 2nd SPES Workshop, Legnaro, May 2014

Simulations (I) 208Pb + 85Rb at 1.2 and 1.5 x VCoulomb Looking at entry distributions for Br (-2p) and Po (+2p) fragments Br projectile-like Po target-like The Zagrebaev-Greiner model to calculate charge, mass and energy distributions of multi-nucleon transfer reaction fragments ECM = 362 MeV The model uses the sliding friction approach for dissipation of relative motion angular momentum into the rotation of nuclei At each of the two energies the entry distributions have well defined, strong maxima, especially in angular momentum Can we measure this with PARIS? ECM = 450 MeV V. Zagrebaev and W. Greiner, J. Phys. G (London) 34, 1 (2007) Phys. Rev. Lett. 101, 122701 (2008) courtesy of V. Zagrebaev W. Królas , IFJ PAN @ 2nd SPES Workshop, Legnaro, May 2014

Simulations (II) 208Pb + 85Rb at 1.2 x VCoulomb Calculated H-K plots for both Br (-2p) and Po (+2p) fragments (sum measurement) The PARIS response calculated using: GEMINI++ code for deexcitation: emission of particles (neutrons), statistical and discrete gamma-rays GEANT4 for detector response in the 2p, 108 segment configuration M. Ciemała et al., Acta Phys.Pol. B44, 611 (2013) Is it possible to resolve contributions to the „sum” H-K plots from the light and heavy fragments? ECM = 362 MeV courtesy of M. Ciemała W. Królas , IFJ PAN @ 2nd SPES Workshop, Legnaro, May 2014

Simulations (III) 208Pb + 85Rb at 1.2 x VCoulomb 210Po 85Br Is it possible to resolve contributions to the „sum” H-K plots from the light and heavy fragments? Depends on the correlation in the excitation of fragments If, within one event, the PLF fragment is highly excited but the TLF has only low excitation energy, this should give a clear separation on the H-K plot Can gating on specific g transitions or bands be used to enhance selectivity? Sum of 85Br and 210Po responses emission not simultaneous (g ’s from either 85Br or 210Po in one event) 85Br and 210Po emissions (simultaneous) in every event 210Po 85Br W. Królas , IFJ PAN @ 2nd SPES Workshop, Legnaro, May 2014

Much needed ancillary detectors readily available: Why SPES ? The beams A large choice of stable and radioactive beams covering long isotopic chains For instance, for Day 1 experiment: Rb beams on heavy 208Pb or 198Pt targets Stable 85Rb and 87Rb beams Radiactive Rb beams up to 98Rb, e.g. 90Rb and 96Rb at ~10^7 ions/sec Possible to explore beams of one element with large N/Z spread (1.29, 1.42 and 1.59) The detectors PARIS4SPES 2p array of phoswich scintillators with excellent characteristics to measure both sum energy and multiplicity Much needed ancillary detectors readily available: PRISMA magnetic spectrometer (isotopic ID) GALILEO Ge detectors array RFD for high efficiency recoil tagging (no ID) energy isospin W. Królas , IFJ PAN @ 2nd SPES Workshop, Legnaro, May 2014

http://paris.ifj.edu.pl W. Królas, M. Kmiecik, P. Bednarczyk, B. Fornal, A. Maj, M. Ciemała, M. Ziębliński et al. Institute of Nuclear Physics PAN, Kraków, Poland F. Crespi, A. Bracco, S. Leoni, F. Camera, G. Benzoni, O. Wieland, B. Million et al. University of Milano and INFN, Italy F. Azaiez, J. Wilson, IPN Orsay, France Ch. Schmitt, GANIL, O. Dorvaux, IPHC Strasbourg For coupling of PARIS to a spectrometer or the GALILEO and Recoil Filter Detector: collaboration with the PRISMA spectrometer group at Laboratori Nazionali di Legnaro and/or collaboration with the gamma spectroscopy group at Legnaro and the RFD Kraków is much needed: looking forward to opinions and discussion… PARIS4SPES W. Królas , IFJ PAN @ 2nd SPES Workshop, Legnaro, May 2014