WCI 2004 session 3: DATA SORTING
Can we extract mechanism?
Can we extract sources in space-time?
What are the differences between p-A and A-A collisions?
WCI 2004: 3- SORTING
Catania
January 2004
SORTING : Why? Two complementary philosophies
1- Global overview of data versus collision violence, energy,
global comparison with models :
IPS = geometry (e.g. Mtot,ET,ET12,ZTOT,TKEL…)
 IPS do not allow to select mechanisms.
 IPS = impact parameter mixing around Fermi energy
OR
2 – Select a given mechanism, an emission source :
Use several global variables, statistical techniques.
 « Physics of the sorting » ? Check what you select
 Mechanism  impact parameter (large fluctuations E 100 AMeV)
SORTING IS DETECTOR DEPENDENT
WCI 2004: 3- SORTING
Catania
January 2004
Impact parameter selector and detector response
Central collisions : upper 10%
of IPS distributions
Correlations between
NIMF and IPS is
Detector dependent
 Nc  ET
 ZMR  Zdet
 NH  ZLCP
Llope et al. PRC 51(1995) 1325
WCI 2004: 3- SORTING
A powerful detector gives
closer variances and
normalised variances of IMF
distributions whatever
the IPS (but also lower
mean values for IPS based on
lcp )
INDRA
Catania
January 2004
IPS : event mixing
IPS = transverse energy
Experimental data
Doré et al. (INDRA) PLB491(2000) 15
DYWAN simulation
(wavelets)
Jouault et al. NPA 628(1998) 119
De la Mota &Sébille EPJA 12 (2001) 479
Verify IPS range data/model
Treat both in same way
WCI 2004: 3- SORTING
Catania
January 2004
IPS : Disentangle QP and MR emissions
Get proportions and properties of both types of emissions
(sources ?), which may differently depend on b
See Olmi
Most peripheral collisions b0.6 bmax . IPS=TKEL
Results depend on assumption for QP emission
(isotropic or not)
WCI 2004: 3- SORTING
Catania
January 2004
Coulomb proximity decay: evaporation from PLF
Hudan et al. Nucl-ex/0308031

Simulation : inv in j for emitting j from
PLF parameterised as j(E) = R2fj(1-Uc/E)
Modified Uc=ZfZj/Rfj + ZTLFZj/RTLFj
+ ZTLFZf/RTLFf - ZTLFZ/RTLFPLF
Lower B  emission favoured between PLF
and TLF in early emission :
RTLFPLF =30-70 fm (t250 fm/c)
Data 50 AMeV Cd+Mo:
 from PLF (E22 MeV)
Including early emission increases
APLF and * from 2.3 to 4 MeV.
Influence on mid-rapidity « source ».
WCI 2004: 3- SORTING
Catania
January 2004
Data sorting: Identify mechanisms
use complete events (QP or single source)
 see M. Bruno, Srivastava, INDRA
Peripheral collisions
select events with minimum MR emission :
velocity, momentum criteria (Bruno, Bougault)
Charge density (INDRA)
Remove preequilibrium Au+C (Srivastava)
Central collisions:
 Complete events and event shape (flow) (Bruno, INDRA)
 Multidimensional analyses (INDRA)
WCI 2004: 3- SORTING
Catania
January 2004
Data sorting:
from pure binary events
to single source
2.5mb
Tool: charge density vs
c.m. velocity along event axis
36Ar+58Ni
95 AMeV
Complete events:
80% of total charge and
linear momentum detected
(semi-central and central
collisions) - 145 mb (5.2% R)
E. Galichet PhD thesis,
and NIM A 441 (2000) 517
WCI 2004: 3- SORTING
0.7 mb
Parallel velocity
Catania
January 2004
Data sorting: selection of central events
Au+C, Au + Cu, Au + Au
Well detected
>90% Ap+T
and spherical events
θflow > 60o
Central collisions
25 AMeV Au+C
Au+Cu Au+Cu
*=1.5
*=3
*=4.5
Some percent of the
measured
cross section
Au+Au 35 AMeV
*=7 A.MeV
ISOTROPY
WCI 2004: 3- SORTING
Nucl. Phys. A 724 (2003) 455
Catania
January 2004
Selection of compact single source:
complete events and flow angle
INDRA
J.D. Frankland et al.
NPA 689 (2001)
Flow angle
Calculated with
Fragments only
(Z  5)

WCI 2004: 3- SORTING
lcp properties
show evolution
from binary to
fusion collisions
Catania
January 2004
Sorting :Statistical techniques
 Work in multidimensional space
 Project on a discriminant plane, or axis
Principal Component Analysis
Chimera variable
Discriminant Analysis
Neuronal Network
Enlarge the samples
Their properties must be
carefully verified
INDRA central collisions
See N. Le Neindre
WCI 2004: 3- SORTING
Catania
January 2004
Data sorting is equivalent to creating a
statistical ensemble
Characterize
The pertinent variables
The type of statistical ensemble
See Francesca Gulminelli
WCI 2004: 3- SORTING
Catania
January 2004
Space-time extent of sources
Can we disentangle space and time ?
Interferometry
New technique to partly avoid space and time mixing
Imaging (B. Lynch)
Velocity correlations (lcp-IMF, IMF-IMF)
(Geraci, De Souza, Natowitz)
WCI 2004: 3- SORTING
Catania
January 2004
Bill
Lynch
WCI 2004: 3- SORTING
Catania
January 2004
p-A versus A-A
Similarities and differences between reactions
F-F emission time vs E* (Beaulieu PRL84(2000)5971)
Similar above 4-5 AMeV : Multifragmentation region
Nautilus
Ar+Au & Kr+Au
WCI 2004: 3- SORTING
Catania
January 2004
In p-A reactions
• single source – no neck emission
• simplest case for thermal effects
• negligible deformation, angular momentum effects
• formation of hot residue in a dilute state
• no compression
• entropy per nucleon reaches maximum very rapidly
• residues formed over full range of E* with one beam
• limited maximum E*/A due to transparency effects
V. Viola
See Karnaukhov
WCI 2004: 3- SORTING
Catania
January 2004
MF: more or less compression in central HI collisions
Depends on entrance channel
asymmetry
2 systems, 1 th (same partitions)
Different KE of fragments
1 asymmetric system, 2 th.
Same KE of fragments
Bellaize et al. (INDRA) NPA709 (2002) 367
WCI 2004: 3- SORTING
Catania
January 2004
p-A and A-A at high excitation
KE : Coulomb
Zs=59 th 6.5MeV
MIMF  /ZS  =0.065
Beaulieu et al (ISiS) PRC64 (2001)
th and ZS from SMM (backtr)
Zs=75 th  6.5 MeV
MIMF  /ZS  0.095
Bellaize et al. (INDRA)
O. Lopez (INDRA)
Zs=68 th  6.2 MeV
MIMF  /ZS  0.10
In p-A vs central A-A for th  6. MeV : less fragments,
and similar fragment KE.
Uncertainties on th ? On ZS? Detector efficiencies on MIMF
WCI 2004: 3- SORTING
Catania
January 2004