GLOBAL RESULTS CHIMERA

1
Heavy ions studies with the detector CHIMERA at
the LNS in Catania Recent achievements and
Perspectives
Angelo Pagano INFN Sezione di Catania
Dipartimento di Fisica ed Astronomia Università
di Catania-Italy- angelo.pagano_at_ct.infn.it
Venezia-NuPECC Meeting18th March 2005
http//www.nupecc.org/misc/communications.html
2
outline

• Introduction
• Fermi Energy domain and existing detection
  systems
• CHIMERA performances
• CHIMERA campaigns on 2000 (REVERSE)
• - CHIMERA FULL 2003 and 2004
• Selected results
• Global Variables
• Isospin contents of Fragments
• Dynamical component of the Fragment production
• Light Fragment (IMF)
• Dynamical Fission(DF)
• LCP
• central collisions
• Isoscaling
• ()Perspectives CHIMERAPS
• RD Digital
  Acquisition

()For CHIMERA/ISOSPIN collaboration
3
FERMI I
Our work concerns with heavy ion collisions (HI)
in the Fermi energy domain 20 MeV/nucleon lt
E/A lt 100 MeV/nucleon In this domain the
reaction experiences the transition from the
dynamics driven by the mean field to the dynamics
dominated by a short mean-free path
nucleon-nucleon interactions. Consequently one
can observe the appearance of new phenomena (
Multifragmentation -Phase transition of finite
systems) A.Bonasera, M. Di Toro and Ch. Gregoire
Nucl. Phys. A 463 (1987) 653 G. Peilert, H.
Stöcker and W. Greiner Rep. Prog. Phys., 57,
(1994) 533.
??
Understanding this transition from binary
reactions (or fusion), most probable at low
energies, to more complex multi-body reactions
becoming dominating at intermediate and high
energies is one of the key activity of the
recent heavy ion research in this energy region.
4
DETECTORS for H.I.reaction studies
Nautilus MSU 4? MINIBALL
(80) INDRA (90) CHIMERA (95)
NIMROD FIASCO FOPI (EgtgtEF)
HERACLES GARFIELD (EltEF) MEDEASOLEM
adapted from N.Le Neindre, R.De Souza, A.P.
contribution at WCI 2005 (USA)
Auxiliary detectors
Heavy-Ions
LASSA,HiRA, MUST(I,II)
4?
Properties of Nuclear matter away from equilibrium
Projectile decay fragmentation
n detection
Light-ion
ORION Superball NIMROD LAND EDEN DEMON
n-walls
ARGOS EOS ALADIN, FAUST, MULTICS FIRST
ISiS, FASA
5
why
I)NUCLEAR FRAGMENTATION ii)DECAY OF EXCITED
SYSTEMS iii) EOS OF THE NUCLEAR MATTER
In recent years, there was an increasing interest
for a) Liquid-phase transition b) Time scale
and kronology of fragments production c) ISOSPIN
physics and Asymmetry energy term of EOS
Exotic beam
6
IDEA(1994)
THE CHIMERA DETECTOR Installed at LNS-Catania
January 2003
beam
176
TARGET
BEAM
30
176
504
688
1192 Si-CsI(Tl)
1
PD 18x18 mm2
A,Z
1m
?4m
300?m 5 ? 12 cm 25cm2 8000?cm
Identification Methods ?E(Si)-E(CsI(tl))
CHARGE, ISOTOPES E(Si) TOF(Si) VELOCITY -
MASS PULSE SHAPE in CsI(Tl) for LCP
EXPERIMENTAL achievements (unique) -HIGH
GEOMETRICAL EFFICIENCY (??/4? ? 95 ) -LOW
DETECTION THRESHOLD (E/A lt 0.3 MeV/A for H.I.)
-HIGH GRANULARITY ( Ncells/ltMgtultiplicity
gt 40 in 4? ) -PARTICLE IDENTIFICATION
(p,d,t,3He,.6,7Li,.) -ISOTOPE IDENTIFICATION
for IMF 3 lt Zlt 10 (E/Agt 10 MeV/nucleon)
7
Large scattering chamber
MAGNEX
CATANA
aa
CHIMERA
MEDEA
LNS-CATANIA
8
REALITY 0
beam
Si
CsI
(Tl)
1997 (III) Coupling CHIMERA with INDRA
1-2.5
2000-2002 PULSE SHAPE
R. Bougault Nouvelles du Ganil n.60 1997
G.Lanzalone Thesis Università Catania (1998)
J.C. Steckmeyer et al. BORMIO 2002 L.Manduci
Thesis Universitè Caen (2004) J.C. Steckmeyer PRL
submitted (2004)
R.Bassini et al. INFN-MI
9
(No Transcript)
10
REALITY I
The Forward part 2000 REVERSE experiment
CICLOPE Reaction Chamber at LNS
beam
1
11
REVERSE Campaign 2000
The experiments were started by using the FORWARD
part of the apparatus covering the angular range
1lt ? lt 30 , 0 lt f lt 2?
100 projectile fragmentation (? gt 1) ? 70
(LPC) , ? 90(IMF) central collisions
Items CLUSTER (Spoke A.P. ) Transition
mechanism in the production of intermediate mass
fragment ( IMF ) 124Sn 64Ni 25 A.MeV-35
A.MeV 124 Sn 27Al ISOSPIN (Spoke A.P. )
(isospin degree of freedom) 112,124Sn 58,64Ni
35 A.MeV
() A. Pagano et al., Nucl. Phys. A681, 331
(2001). A. Pagano et al., Nucl. Phys. A734,
504 (2004).
12
FORWARD RESULTS
1lt ? lt 30 REVERSE
Z50
Z
Z,A
N.Le Neindre et al , NIM A490 (2002) 251
HF OR
A
?t?700psec ?E/E 0.5 (E.S.)
M.Alderighi et al , NIM A489 (2002) 257
13
REALITY II
The Sphere Of CHIMERA December 2002
176
30
beam
14
Backward results ?gt30
Z8
Alt10
15
4?
REVERSE 1999 2000 ISOSPIN 2002-2003
November 2002
30
1
16
DAQ
GENERAL ARCHITECTURE OF THE SYSTEM
FDL link
Experimental Room
F D L
F D L
F D L
VME 9U
VME 9U
VME 9U
Crate 1
Crate 2
Crate 5
CAMAC 1
NIM 1
V C C
F D L
F I C
V I C
F I C
CAMAC 2
NIM 2
Readout VME 6U
Setup VME 6U
V C C
CAMAC 10
NIM 13
V C C
RS232/486
?s
Ethernet Link
?s
?s
CONSOLLE
Acquisition Room
storage
PC-DSP on line calculation and control
PC Database setup
PC - NIM remote control
UNIX WORKSTATIONS on line analysis and
17
CHIMERA Campaign 2003
2003 EXPERIMENTS ISOSPIN (A.Pagano-Sez.Catania)
124Sn 58,64Ni 25 MeV/A 124Sn 27Al
25 MeV/A 124Sn 58,64Ni 35
MeV/A 112Sn 58,64 Ni 35 MeV/A 124Sn
124,112Sn 35 MeV/A TEST SEMIPERIPHERAL(G.Pogg
i-Sez. Firenze) 112Sn 112Sn 35
MeV/A DISSIPATION (J.Wilczynski-Otwock,A.Pagano-Se
z. Catania) 197Au 197Au 15 MeV/A 197Au 12C
15 MeV/A LIMITING(G.Cardella-Sez.
Catania) 40 Ca 48,40Ca 25 MeV/A 40 Ca
46Ti 25 MeV/A ALPHACLUSTER(B.Borderie-Orsay)
40 Ca 12C 25 MeV/A CHIMERAPS(A.Pagano
G.Politi-Sez.Catania) 58Ni 27Al 25
MeV/A THERMO(M.Bruno-Sez. Bologna) 58Ni 40,48Ca
25 MeV/A
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CHIMERA Campaign 2004
2004 EXPERIMENTS MID-VELOCITY (A.Olmi/G.Poggi-Sez
. Firenze) 58 Ni 58Ni , 112Sn 35,45
MeV/A 112 Sn 58Ni , 112Sn 35
MeV/A CHIMERAPS(A.Pagano-G.Politi Catania) 20 Ne
27 Al 21 MeV/A CECIL (U.Schroeder-Rochester
A.Pagano Catania) 112Sn 112Sn 35,45
MeV/A ISO-EOS (B.Lynch-MSU) 124Sn 112,124Sn
35 MeV/A DIPROTON (G.Cardella,G.Raciti-Catania,LN
S) 20Ne 45 MeV/A CALIBRATION BEAMS(A.Pagano CT)

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CASE 1 GLOBAL-reconstruction REVERSE
No gamma and neutrons included
1lt ? lt 30
124Sn64Ni 35A.MeV
ZCN
ZProj
Ztarg.
bad
20
CASE 2 Isospin contents
See for example S.Pirrone et al. NBL
Lipari(2001) E.DeFilippo et al. IWM2001 Catania
(2002) A.P. SCI 2002 ,ORLANDO (USA)
124Sn64Ni 124Sn27Al 112Sn58Ni
1.40 1.18
Calculations by M.Colonna(LNS) In progress
Nucl. Phys.A703(2002)603-632
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Fragment production
UNIQUE ANALYSIS WITH CHIMERA
Recent results relevant reaction mechanisms
General The multiplicity and the role of
fragments of intermediate mass (IMF) increase
with increasing bombarding energy and centrality
of the collision around 100A.MeV. At higher
energies vaporisation of the nuclear system in
nucleons and particles assumes a dominant role.
Central idea At the Fermi energies, expansion of
the participant zone in nearly central collisions
leads to abounding production of IMFs. Their
energy spectra and production cross sections
provide valuable information on the nuclear
equation of state and dynamical properties of hot
nuclear matter().
In the following we start with the analysis of
semi-peripheral reactions in which one can
observe the onset of IMF production in ternary
events. Ternary splitting is the precursor of the
most dissipative multifragmentation process
observed for central collisions. () see for
example B. Borderie, J. Phys. G Nucl. Part.
Phys. 28 R217 (2002). P. Chomaz, M. Colonna, and
J. Randrup, Phys. Rep. C 389 263 (2004).
22
TERNARY EVENTS SELECTION Dynamical analysis
Z1
Z3
Z2
23
properties
e-?z
30
BNV
V. Baran, M. Colonna, and M. Di Toro, Nucl.
Phys. A 730, 329 (2004).
24
Interpretation-IMF
Ternary events have been the object of different
investigations. Neck breaking mechanisms have
been suggested triggered by transport model
simulations M.Colonna et al., Prog. Part. Nucls.
(1992), 30-17. C.P. Montoya et al. PRL73, (1994)
3070. J.F. Lecolley et al., PL B354, (1995)
202-207. J.Toke et al, PRL 75,2920(1995) M.Colonn
a et al. NPA A589 160(1995) W.G.Lynch, NPA 583,
471 (1995) J.F.Dempsey et al., PRC 54,1710
(1996) J.Lukasik et al, PRC 55, 1906 (1997) L.
Sobotka, et al., PRC 55 (1997) 2109 R.Nebauer and
J.Aichelin, NPA 650,65(1999) E.Plagnol et al, PRC
61, 014606 (2000) T.Lefort et al., NPA662, (2000)
397-422 D.Doré et al., PRC 63, 034612
(2001) P.Milazzo et al. PLB 509B (2001)
204 G.Poggi, NPA 685, 296c (2001) A.S. Botvina
and I.N. Mishustin, PRC 63, 061601
(2001) S.Piantelli et al, PRL 88, 052701
(2002) P.M. Milazzo et al., NPA 703, 603
(2002) V.Baran et al., NPA 703,603 (2002)
B.David et al., PRC 65, 064614(2002) J.Lukasik
et al. arXivnucl-ex/0301018 v1 28Jan 2003 See
also L.G.Moretto et al, PRL 69, 18
(1992) W.Bauer et al., PRL 69, 467(1992) A.A.Stefa
nini et al., Z. Phys. A 351, 167 (1995) F.Bocage
et al. , NPA 676, 391 (2000) J.Colin., PRC 67,
064603 (2003)
25
Wilczynski-2Plot
Stochastic BNV Calculation
1
1
Vr2
Definitive Time scale evaluated by Wilczynski
(E.De Filippo et al. PRC In press)
First preliminary evaluation presented at
WCI2004 LNS - A. P. (January 2004)-
26
TIME SCALE
The majority of IMFs are produced within 100
fm/c after the system starts to re-separate.
On the average, lighter IMFs are produced
earlier than heavier fragments. In order to form
a heavier IMF in the neck region, the system has
to expand to a larger distance, of about 20 fm.
Consequently, these heavy IMFs are produced in
sequential rather than prompt mechanism.
27
Co-linearity
()
28
We have shown that the majority of light IMF's
are produced within 40-80 fm/c after the system
starts to reseparate. On the average, lighter
IMF's are produced earlier than heavier fragments
(kronology). We found that heavy fragments of Z
12 ? 18 are formed at times of about 120 fm/c
after the reseparation, or later. These results
are extremely important for determining basic
ingredients (as for examples Asy-EOS,
?n-n(?)..) for microscopic-transport theory
()
Time distributions of the probability of
formation of the neck remnants (IMF's) predicted
with the stochastic BNV transport model() for
different impact parameters.
() V. Baran, M. Colonna, and M. Di Toro, Nucl.
Phys. A 730, 329 (2004).
29
upgrading
Motivations ISOSPIN Physics at Fermi energy
with CHIMERA , possible applications for Exotic
beams
Charge identification by Pulse Shape for
particles stopped in the n-type large area
silicon detector(2005-2007)
Results for 40Ar12C 20 A.MeV LNS Catania
Method Double Constant Fraction Discrimination
(30-90)
TDC
CFD30 Start
Si PA Amp Split
T
E
CFD90 Stop
QDC
Fig. - a) Kinetic-energy/rise-time
identification matrix. Rise time is obtained by
the Double-CFD method (Rise Time T90-T30)
-b) Zoom of Fig. 2 a), obtained with additional
requirement that the particles are stopped in the
silicon detector.
30
Digitalizzazione II
Only Preamplifier
Work in progress (Milano-Catania collaboration)
31
papers
Dynamical analysis A.Pagano et al., Nucl.
Phys. A734, 504 (2004). E. De Filippo et al., in
press (2004) E.De Filippo et al. Submitted
(2004)
Central collision and ISOSPIN analysis A.Pagano
et al., Nucl. Phys. A681, 331 (2001) E. Geraci et
al., Nucl. Phys. A732, 173 (2004)
Experimental methods S. Aiello et al., Nucl.
Phys. A583, 461 (1995) S.Aiello et al. Nucl.
Instr. Meth. A369, 50 (1996) S.Aiello et al.
Nucl.Instr. Meth. A400, 469 (1997). M. Alderighi
et al., Nucl. Instr. Meth. A489, 257 (2002). N.
Le Neindre et al., Nucl. Instr. Meth. A490, 251
(2002). M. Alderighi et al. Nuclear Physics A 734
(2004) E88E91 M.Alderighi et al. IEEE Trans.
Nucl. Sci., 51, no. 4, pp. 1475-1481
(2004) M.Alderighi et al. IEEE Trans. Nucl. Sci.,
in press M.Alderighi et al. IEEE Trans. Nucl.
Sci., in press
22 Conferences proc. and Inv. Talk n.8 Thesis
University (Catania and Milano) n.6 PhD Thesis
University (Catania and Milano)
32
Conclusions
CHIMERA is a very efficient detector recently
installed at LNS in Catania for
Multifragmentation studies at the medium Fermi
energies. The experimental results prove its very
high capability in detecting fragments as well as
light charged particles created in
nucleus-nucleus interactions. Different
contributions in the field of reaction analysis
as well as detection method have been produced in
recent years. As an example of unique physical
analysis performed with CHIMERA, we have shown
ternary reactions involving emission of IMFs in
a wide range of atomic numbers, up to Z 20. In
all these reactions the IMFs are emitted
preferentially with velocities intermediate
between those of the PLF and TLF as expected for
a neck fragmentation between projectile and
target at the early stage of the reaction. The
time scale and the time sequence of the process
have been established in a model independent way.
The CHIMERA apparatus will be upgraded by Pulse
shape Methods on Si detector (2005-2007) for
ISOSPIN applications We think also extremely
important to progress in the direction of ISOSPIN
physics and Exotic nuclei
33
Collaboration
The CHIMERA/REVERSE/ISOSPIN COLLABORATION
INFN, Sezione di Catania and Dipartimento di
Fisica e Astronomia, Università di Catania, Italy
INFN, Laboratori Nazionali del
Sud and Dipartimento di Fisica e Astronomia,
Università di Catania, Italy INFN,
Gruppo Collegato di Messina and Dipartimento di
Fisica, Università di Messina, Italy INFN,
Sezione di Milano and Instituto di Fisica
Cosmica, CNR, Milano,Italy INFN, Sezione di
Milano and Dipartimento di Fisica Università di
Milano, Italy
Institute for Physics and Nuclear Engineering,
Bucharest, Romania
Institute of Physics,
University of Silesia, Katowice, Poland

M. Smoluchowski Institute of
Physics, Jagellonian University, Cracow,
Poland Institute de Physique Nucleaire,
IN2P3-CNRS and Université Paris-Sud, Orsay,
France LPC,
ENSI Caen and Université de Caen, France

INFN, Sezione di
Bologna and Dipartimento di Fisica, Università di
Bologna, Italy Saha Institute of Nuclear Physics,
Kolkata, India

GANIL, CEA, IN2P3-CNRS, Caen, France,

H.
Niewodniczanski Institute of Nuclear Physics,
Cracow, Poland
DAPNIA/SPhN,CEA-Saclay, France


IPN, IN2P3-CNRS and Université Claude
Bernard, Lyon, France
Institute of
Modern Physics, Lanzhou, China

Institute of
Experimental Physics, Warsaw University, Warsaw,
Poland
INFN, Sezione Napoli and
Dipartimento di Fisica, Università di Napoli

Institute for Nuclear Studies, Swierk/Warsaw,
Poland
34
Future?
III generation detector should satisfy to main
requirements (upgrading of existing devices
specific modules??) A)MANDATORY! Integrate
performances of II generation devise n flexible
and transportable device stability of the
detector electronics for Exotic beam
application B)MANDATORY! Improve Data analysis
and calibration full digitalisation of the
signal Digital Signal processing Neural
approaches? Implement computation?? MOTIVATIONS
necessity of Z and A identification up to about
Z ? 30 atomic charge unit this kind of
experiments for isoscaling in both pheriperal
and central collisions Isospin realaxation Memory
effects in projectile fragmentation Calorimetry
and source reconstruction precise measurements
of flow neck fragmentation Asymmetry term in
nuclear EOS Space time correlation with relative
momentum resolution lt few MeV/c This kind of
experiments are important for Spatial Size and
density of emitting source Time sequences
Imaging Isospin relaxation
35
DF
36
CASE 3 DALITZ
Charge distribution-Dalitz Plotfor complete
events Ztotgt 40
124Sn64Ni 35A.MeV
Mclt 7
VP/2 VP
7 ltMclt12
VCM
Mcgt12
37
ISOSCALING
ISOSCALING
H. Xu et al, PRL 85, 716 (2000).
Work in progress E. De Filippo et al., to be
published
38
Fragment Charge and multiplicity
Y(Z)
1 2 3
As conventional (useful) classification

• Peripheral
• Semi-peripheral
• central

39
CENTRAL
Isoscaling in central collisions
E. Geraci et al. / Nuclear Physics A 732 (2004)
173201
Summary E. Geraci et al., Nucl. Phys. A732, 173
(2004).
40
LCP
Ratio of isotope yield for Z1 charge as a
function of the total multiplicity
1 2 3 4
1 2 3 4
Increasing ratios with increasing Mc L.G.Sobotka,
PRC 50,(1994) M.Di Toro et al.NPA
681,(2000) ..
Comparison with the results on isotopic behaviour
at midrapidity for fragments for the reaction
114Cd98Mo at 50 A.MeVH. Xu et al. Phys. Rev.
C65, 061602, 2002
41
SIS3301 - 8 channel VME Fast Sampling ADC by SIS
SIS Struck Innovative System, Hamburg,
Germany
42
TIME SCALE evaluation
The time scale of the IMF emission is estimated
in a very simple one-dimensional calculation. It
is assumed that in a semiperipheral collision of
a projectile P and a target T, the primary binary
system P T starts to re-separate along the
beam direction having at the time t 0 a given
relative velocity Vrel
A sequential decay scenario is assumed The IMF
is emitted either from the projectile primary
fragment P at the separation time tsep PT
?PT, (separation from the projectle) P ?
PLFIMF, or from the target primary fragment .
Starting from t 0, till asymptotic values are
reached, all the fragments move in the mutual
Coulomb repulsion field. In our simplified
calculation we assume that the fragment IMF is
formed from the matter of both, projectile and
target, proportionally to their initial masses
and charges.
E.De Filippo et al. to be published
43
Digitalizzazione I
Exp.LNS 2002-3 CHIMERAPS