WCI 2004: 3- SORTING Catania January 2004 WCI 2004 session 3: DATA SORTING Can we extract mechanism? Can we extract sources in space-time? What are the

WCI 2004: 3- SORTING Catania January 2004

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?


SORTING : Why? Two complementary philosophies1- 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

SORTING IS DETECTOR DEPENDENT

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)

OR


Impact parameter selector and detector response

Llope et al. PRC 51(1995) 1325 INDRA

Correlations between NIMF and IPS isDetector dependent

A powerful detector givescloser variances and normalised variances of IMFdistributions whateverthe IPS (but also lower mean values for IPS based on lcp )

Central collisions : upper 10%of IPS distributions

Nc ET

ZMR Zdet

NH ZLCP


IPS : event mixing

DYWAN simulation (wavelets) Jouault et al. NPA 628(1998) 119De la Mota &Sébille EPJA 12 (2001) 479

Experimental dataDoré et al. (INDRA) PLB491(2000) 15

IPS = transverse energy

Verify IPS range data/modelTreat both in same way


IPS : Disentangle QP and MR emissions

Get proportions and properties of both types of emissions (sources ?), which may differently depend

on bSee Olmi

Most peripheral collisions b0.6 bmax . IPS=TKEL

Results depend on assumption for QP emission(isotropic or not)


Coulomb proximity decay: evaporation from PLF

Simulation : inv in j for emitting j from PLF parameterised as j(E) = R2

fj(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 (t250 fm/c)

Data 50 AMeV Cd+Mo: from PLF (E22 MeV)

Including early emission increases APLF and * from 2.3 to 4 MeV.Influence on mid-rapidity « source ».

Hudan et al. Nucl-ex/0308031


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)


Data sorting: from pure binary events to single source

Tool: charge density vs c.m. velocity along event axis

36Ar+58Ni 95 AMeVComplete 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

Parallel velocity

2.5mb

0.7 mb


Data sorting: selection of central events

Central collisionsAu+C Au+Cu Au+Cu Au+Au*=1.5 *=3 *=4.5 *=7 A.MeV

Nucl.Phys.A 724 (2003) 455

25 AMeV 35 AMeVCentral collisions

Au+C Au+Cu Au+Cu Au+Au*=1.5 *=3 *=4.5 *=7 A.MeV

Nucl.Phys.A 724 (2003) 455

Central collisionsAu+C Au+Cu Au+Cu Au+Au*=1.5 *=3 *=4.5 *=7 A.MeV

Nucl.Phys.A 724 (2003) 455

25 AMeV 35 AMeV

Au+C, Au + Cu, Au + Au

Nucl. Phys. A 724 (2003) 455

ISOTROPY

Well detected >90% Ap+T

and spherical events θflow > 60o

Some percent of the measured cross section


Selection of compact single source: complete events and flow angle

Flow angle Calculated withFragments only(Z 5)

INDRAJ.D. Frankland et al.NPA 689 (2001)

lcp propertiesshow evolution from binary to fusion collisions


Sorting :Statistical techniques

Work in multidimensional space Project on a discriminant plane, or axis

Principal Component AnalysisChimera variableDiscriminant AnalysisNeuronal Network

Enlarge the samplesTheir properties must be carefully verified

INDRA central collisionsSee N. Le Neindre


Data sorting is equivalent to creating a statistical ensemble

Characterize The pertinent variables The type of statistical ensemble

See Francesca Gulminelli


Space-time extent of sources

InterferometryNew technique to partly avoid space and time mixing

Imaging (B. Lynch)

Velocity correlations (lcp-IMF, IMF-IMF)(Geraci, De Souza, Natowitz)

Can we disentangle space and time ?


BillLynch


p-A versus A-A

Similarities and differences between reactions

Ar+Au & Kr+Au

Nautilus

F-F emission time vs E* (Beaulieu PRL84(2000)5971)

Similar above 4-5 AMeV : Multifragmentation region


• 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

In p-A reactions

V. ViolaSee Karnaukhov


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


p-A and A-A at high excitation

Zs=75 th 6.5 MeVMIMF /ZS 0.095

Zs=68 th 6.2 MeV MIMF /ZS 0.10

th and ZS from SMM (backtr)

Zs=59 th 6.5MeVMIMF /ZS =0.065

Bella

ize e

t al. (IN

DR

A)

O. Lo

pez (IN

DR

A)

Beaulieu et al (ISiS) PRC64 (2001)

KE : Coulomb

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

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WCI 2004: 3- SORTING Catania January 2004 WCI 2004 session 3: DATA SORTING Can we extract mechanism? Can we extract sources in space-time? What are the