1. 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 2nd SPES Workshop, Legnaro, May 2014

2. 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 2nd SPES Workshop, Legnaro, May 2014

3. 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 2nd SPES Workshop, Legnaro, May 2014

4. 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 2nd SPES Workshop, Legnaro, May 2014

5. 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 2nd SPES Workshop, Legnaro, May 2014

6. 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, (2008)
courtesy of V. Zagrebaev
W. Królas , IFJ 2nd SPES Workshop, Legnaro, May 2014

7. 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 2nd SPES Workshop, Legnaro, May 2014

8. 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 2nd SPES Workshop, Legnaro, May 2014

9. 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 2nd SPES Workshop, Legnaro, May 2014

10.
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 2nd SPES Workshop, Legnaro, May 2014