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Accueil > Recherche & Enseignement

M. Rémi Bougault

Chercheur CNRS


Groupe : Dynamique et thermodynaique nucléaire


bougault lpccaen.in2p3.fr


Tel : +33 2 31 45 25 46


PUBLICATIONS

[in2p3-01348951] New semi-automatic method for reaction product charge and mass identification in heavy-ion collisions at Fermi energies

3 février 2017

This article presents a new semi-automatic method for charge and mass identification of charged nuclear fragments using either ∆E − E correlations between measured energy losses in two successive detectors or correlations between charge signal amplitude and rise time in a single silicon detector, (...)

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[in2p3-01345974] Reaction and fusion cross sections for the near-symmetric system $^{129}$Xe+$^{nat}$Sn from $8$ to $35$ $AMeV$

20 octobre 2016

item[Background]Heavy-ion reactions from barrier up to Fermi energy. \item[Purpose]Reaction and fusion cross sections determination. Fusion reactions induced by $^129Xe$ projectiles on $^natSn$ targets for energies ranging from $8$ A.MeV to $35$ A.MeV were measured with the INDRA (...)

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[in2p3-01100158] Signals of Bose Einstein condensation and Fermi quenching in the decay of hot nuclear systems

6 juin 2016

We report experimental signals of Bose-Einstein condensation in the decay of hot Ca projectilelike sources produced in mid-peripheral collisions at sub-Fermi energies. The experimental setup, constituted by the coupling of the INDRA 4$\pi$ detector array to the forward angle VAMOS magnetic (...)

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[in2p3-01300455] Signals of Bose Einstein condensation and Fermi quenching in the decay of hot nuclear systems

11 avril 2016

We report on first experimental observations of nuclear fermionic and bosonic components displaying different behaviours in the decay of hot Ca projectile-like sources produced in mid-peripheral collisions at sub-Fermi energies. The experimental setup, constituted by the coupling of the INDRA (...)

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[in2p3-01120218] Low-temperature technique of thin silicon ion implanted epitaxial detectors

4 juillet 2015

A new technique of large-area thin ion implanted silicon detectors has been developed within the R&D performed by the FAZIA Collaboration. The essence of the technique is the application of a lowtemperature baking process instead of high-temperature annealing. This thermal treatment is (...)

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[hal-00347268] Isospin diffusion in semi-peripheral $^{58}Ni$+$^{197}Au$ collisions at intermediate energies (I): Experimental results

3 juillet 2015

Isospin diffusion in semi-peripheral collisions is probed as a function of the dissipated energy by studying two systems $^58Ni$+$^58Ni$ and $^58Ni$+$^197Au$, over the incident energy range 52-74\AM. A close examination of the multiplicities of light products in the forward part of phase space (...)

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[in2p3-01110422] Production cross sections for intermediate mass fragments from dynamical and statistical decay of projectile-like fragments in $^{124}$Sn + $^{64}$Ni and $^{112}$Sn + $^{58}$Ni collisions at 35 A MeV

3 juillet 2015

Background: In heavy-ion collisions at intermediate energies the production of light charged particles and intermediate mass fragments (IMFs) is due to different reaction mechanisms and different time scales, ranging from fast dynamical processes to statistical emission from the equilibrated (...)

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[hal-00008456] Estimate of average freeze-out volume in multifragmentation events

3 juillet 2015

An estimate of the average freeze-out volume for multifragmentation events is presented. Values of volumes are obtained by means of a simulation using the experimental charged product partitions measured by the 4pi multidetector INDRA for 129Xe central collisions on Sn at 32 AMeV incident (...)

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[hal-00737435] Nuclear multifragmentation time-scale and fluctuations of largest fragment size

3 juillet 2015

Distributions of the largest fragment charge, Zmax, in multifragmentation reactions around the Fermi energy can be decomposed into a sum of a Gaussian and a Gumbel distribution, whereas at much higher or lower energies one or the other distribution is asymptotically dominant. We demonstrate the (...)

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[hal-00008225] Multifragmentation of very heavy nuclear systems (III): fragment velocity correlations and event topology at freeze-out.

3 juillet 2015

Kinetic energy spectra and fragment velocity correlations, simulated by means of stochastic mean-field calculations, are successfully confronted with experimental data for single multifragmenting sources prepared at the same excitation energy per nucleon in 32 AMeV 129Xe+natSn and 36 AMeV (...)

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[hal-00345772] Bimodal behavior of the heaviest fragment distribution in projectile fragmentation

3 juillet 2015

The charge distribution of the heaviest fragment detected in the decay of quasi-projectiles produced in intermediate energy heavy-ion collisions has been observed to be bimodal. This feature is expected as a generic signal of phase transition in non-extensive systems. In this paper we present (...)

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[in2p3-00024252] Time sequence and time scale of intermediate mass fragment emission

3 juillet 2015

Semiperipheral collisions in the $^124$Sn+$64Ni reaction at 35 MeV/nucleon were studied using the forward part of the Charged Heavy Ion Mass and Energy Resolving Array. Nearly completely determined ternary events involving projectilelike fragments (PLF), targetlike fragments (TLF), and (...)

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[in2p3-01066044] In-medium effects for nuclear matter in the Fermi energy domain

3 juillet 2015

We study nuclear stopping in central collisions for heavy-ion induced reactions in the Fermi energy domain, between $15$ and $100$ A\,\textrmMeV. Using the large dataset of exclusive measurements provided by the $4\pi$ array \emphINDRA, we determine the relative degree of stopping as a function (...)

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[in2p3-00118535] Comparisons of statistical multifragmentation and evaporation models for heavy-ion collisions

3 juillet 2015

The results from ten statistical multifragmentation models have been compared with each other using selected experimental observables. Even though details in any single observable may differ, the general trends among models are similar. Thus, these models and similar ones are very good in (...)

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[in2p3-00023603] Isotopic Scaling and the Symmetry Energy in Spectator Fragmentation

3 juillet 2015

Isotopic effects in the fragmentation of excited target residues following collisions of $^12$C on $^112,124$Sn at incident energies of 300 and 600 MeV per nucleon were studied with the INDRA 4$\pi$ detector. The measured yield ratios for light particles and fragments with atomic number $Z (...)

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[in2p3-00023600] Directed and elliptic flow in $^{197}$Au+$^{197}$Au at intermediate energies

3 juillet 2015

Directed and elliptic flow for the Au + Au system at incident energies between 40 and 150 MeV per nucleon has been measured using the INDRA 4 pi multi-detector. For semi-central collisions, the elliptic flow of Z = 2 particles switches from in-plane to out-of-plane enhancement at around 100 MeV (...)

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[hal-00335974] Fragment properties of fragmenting heavy nuclei produced in central and semi-peripheral collisions.

3 juillet 2015

Fragment properties of hot fragmenting sources of similar sizes produced in central and semi-peripheral collisions are compared in the excitation energy range 5-10 AMeV. For semi-peripheral collisions a method for selecting compact quasi-projectiles sources in velocity space similar to those of (...)

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[in2p3-00025576] Bimodality: a possible experimental signature of the liquid-gas phase transition of nuclear matter

3 juillet 2015

We have observed a bimodal behaviour of the distribution of the asymmetry between the charges of the two heaviest products resulting from the decay of the quasi-projectile released in binary Xe+Sn and Au+Au collisions from 60 to 100 MeV/u. Event sorting has been achieved through the transverse (...)

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[hal-00277843] Multifragmentation threshold in $^{93}Nb+${nat}Mg collisions at 30 MeV/nucleon

3 juillet 2015

We analyzed the $^93Nb$ on $^natMg$ reaction at $30$ MeV/nucleon in the aim of disentangling binary sequential decay and multifragmentation decay close to the energy threshold, i.e. $\simeq 3$ MeV/nucleon. Using the backtracing technique applied to the statistical models GEMINI and SMM we (...)

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[hal-00001474] Model-independent tracking of criticality signals in nuclear multifragmentation data

3 juillet 2015

We look for signals of criticality in multifragment production in heavy-ion collisions using model-independent universal fluctuations theory. The phenomenon is studied as a function of system size, bombarding energy, and impact parameter in a wide range of INDRA data. For very central (...)

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[in2p3-00171092] Yield scaling, size hierarchy and fluctuations of observables in fragmentation of excited heavy nuclei

3 juillet 2015

Multifragmentation properties measured with INDRA are studied for single sources produced in Xe+Sn reactions in the incident energy range 32-50 A MeV and quasiprojectiles from Au+Au collisions at 80 A MeV. A comparison for both types of sources is presented concerning Fisher scaling, Zipf law, (...)

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[in2p3-00024320] Dynamical fission in $^{124}$Sn+$^{64}$Ni collision at 35A MeV

3 juillet 2015

Some properties of fast, nonequilibrium splitting of projectiles in the $^124$Sn+$^64$Ni reaction at 35A MeV were determined using the 4$\pi$ CHIMERA detector system. In particular the charge distributions, in- and out-of-plane angular distributions, and relative velocities of projectilelike (...)

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[in2p3-01067158] Quasiprojectile and intermediate velocity isotopic ratios for light fragments emitted in the Ar 36 +Ni 58 and Ni 58 +Ni 58 reactions between 32A and 84A MeV

3 juillet 2015

Isotopic ratios for light fragments (Z≤4 ) emitted by the quasiprojectile (QP) and the mid-rapidity (MR) sources are investigated by the use of a slightly asymmetric system (Ar 36 +Ni 58 ) and a symmetric one (Ni 58 +Ni 58 ) for six energies between 32A and 84A MeV and three semiperipheral (...)

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[in2p3-00023886] Neutron to proton ratios of quasiprojectile and midrapidity emission in the ${58}$Ni-${58}$Ni reaction at 52 MeV/Nucleon

3 juillet 2015

By combining data from a charged particle $^58$Ni+$^58$Ni experiment at 52 MeV/nucleon with an $^36$Ar+$^58$Ni experiment at 50 MeV/nucleon for which free neutrons have been detected, an increase in the neutron to proton ratio of the whole nuclear material at midrapidity has been experimentally (...)

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[hal-00454499] New scalings in nuclear fragmentation

3 juillet 2015

Fragment partitions of fragmenting hot nuclei produced in central and semiperipheral collisions have been compared in the excitation energy region 4-10 MeV per nucleon where radial collective expansion takes place. It is shown that, for a given total excitation energy per nucleon, the amount of (...)

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[hal-00821065] Constrained caloric curves and phase transition for hot nuclei

3 juillet 2015

Simulations based on experimental data obtained from multifragmenting quasi-fused nuclei produced in central $^129$Xe + $^nat$Sn collisions have been used to deduce event by event freeze-out properties in the thermal excitation energy range 4-12 AMeV [Nucl. Phys. A809 (2008) 111]. From these (...)

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[in2p3-00118543] Calorimetry

3 juillet 2015

Methods for determining the heat content E */A of hot nuclei formed in energetic nuclear reactions are discussed. The primary factors involved in converting raw data into thermal physics distributions include: 1) design of the detector array, 2) constraints imposed by the physics of the (...)

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Exploring reaction mechanisms and their competition in 58Ni+48Ca collisions at E = 25 AMeV

2 juillet 2014

Latest results concerning the study of central collisions in 58Ni+48Ca reactions at Elab(Ni)=25 AMeV are presented. The experimental data, collected with the CHIMERA 4π device, have been analyzed in order to investigate the competition among different reaction mechanisms for central collisions (...)

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[in2p3-00986921] Competition between fusion-evaporation and multifragmentation in central collisions in 58Ni+48Ca at 25A MeV

5 mai 2014

The experimental data concerning the Ni-58+Ca-48 reaction at E-lab(Ni)=25A MeV, collected by using the CHIMERA 4 pi device, have been analyzed in order to investigate the competition among different reaction mechanisms for central collisions in the Fermi energy domain. As a main criterion for (...)

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Isospin effects and symmetry energy studies with INDRA

27 mars 2014

The equation of state of asymmetric nuclear matter is still controversial, as predictions at subsaturation as well as above normal density widely diverge. We discuss several experimental results measured in heavy-ion collisions with the INDRA array in the incident energy range 5-80AMeV. In (...)

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[in2p3-00966956] The FAZIA project in Europe: R&D phase

27 mars 2014

The goal of the FAZIA Collaboration is the design of a new-generation 4π detector array for heavy-ion collisions with radioactive beams. This article summarizes the main results of the R&D phase, devoted to the search for significant improvements of the techniques for charge and mass (...)

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Isospin transport in 84Kr + 112;124 Sn collisions at Fermi energies with the FAZIA detector

3 mars 2014

Isotopically resolved fragments up to Z 20 have been studied in a test experiment by the FAZIA Collaboration with a three-stage telescope. The reactions 84Kr+112Sn (n-poor) and 84Kr+124Sn (n-rich) at 35 MeV/nucleon were measured. The telescope was located near the grazing angle, so the detected (...)

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[in2p3-00951103] Energy measurement and fragment identification using digital signals from partially depleted Si detectors

24 février 2014

A study of identification properties of a Si-Si DE-E telescope exploiting an underdepleted residual-energy detector has been performed. Five different bias voltages have been used, one corresponding to full depletion, the others associated with a depleted layer ranging from 90% to 60% of the (...)

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[in2p3-00875063] Isospin effects and symmetry energy studies with INDRA

21 octobre 2013

The equation of state of asymmetric nuclear matter is still controversial, as predictions at subsaturation as well as above normal density widely diverge. We discuss several experimental results measured in heavy-ion collisions with the INDRA array in the incident energy range 5-80 MeV/nucleon. (...)

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[in2p3-00868032] N and Z odd-even staggering in Kr + Sn collisions at Fermi energies

1er octobre 2013

The odd-even staggering of the yield of final reaction products has been studied as a function of proton (Z) and neutron (N) numbers for the collisions 84 Kr+112 Sn and 84 Kr+124 Sn at 35 MeV/nucleon, in a wide range of elements (up to Z ~ 20). The experimental data show that staggering effects (...)

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Coulomb chronometry to probe the decay mechanism of hot nuclei

30 septembre 2013

In $^129$Xe+$^nat$Sn central collisions from 12 to 25 MeV/A, the three-fragment exit channel occurs with a significant cross section. We show that these fragments arise from two successive binary splittings of a heavy composite system. The sequence of fragment production is unambiguously (...)

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Coulomb chronometry to probe the decay mechanism of hot nuclei

27 septembre 2013

In $^129$Xe+$^nat$Sn central collisions from 12 to 25 MeV/A, the three-fragment exit channel occurs with a significant cross section. We show that these fragments arise from two successive binary splittings of a heavy composite system. The sequence of fragment production is unambiguously (...)

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Isospin transport in 84Kr+112,124Sn reactions at Fermi energies

10 septembre 2013

Isospin transport phenomena in dissipative heavy ion collisions have been investigated at Fermi energies with a beam of 84Kr at 35AMeV. A comparison of the /Z of light and medium products forward-emitted in the centre of mass frame when the beam impinges on a n-poor 112Sn and a n-rich 124Sn (...)

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The european FAZIA initiative: a high-performance digital telescope array for heavy-ion studies

6 septembre 2013

The european Fazia collaboration aims at building a new modular array for charged product identification to be employed for heavy-ion studies. The elementary module of the array is a Silicon-Silicon-CsI telescope, optimized for ion identification also via pulse shape analysis. The achievement (...)

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Effects of irradiation of energetic heavy ions on digital pulse shape analysis with silicon detectors

29 août 2013

Detected energy, charge rise-time and pulse shape identfication capabilities of nTD silicon detectors under prolonged irradiation by energetic heavy ions have been studied. Sizeable effects on the amplitude and the risetime of the charge signal have been found for detectors irradiated with (...)

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The Fazia initiative: more powerful detectors for a more detailed investigation on the origin and the decay of charged fragments

29 août 2013

The main results of the R&D program of the FAZIA collaboration are described. The objective was to improve particle identication capabilities from solid-state telescopes made of Silicon detectors and CsI(Tl) scintillators in view of a new large acceptance apparatus to be used for heavy-ion (...)

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Constrained caloric curves and phase transition for hot nuclei

7 mai 2013

Simulations based on experimental data obtained from multifragmenting quasi-fused nuclei produced in central $^129$Xe + $^nat$Sn collisions have been used to deduce event by event freeze-out properties in the thermal excitation energy range 4-12 AMeV [Nucl. Phys. A809 (2008) 111]. From these (...)

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[in2p3-00782509] Effects of irradiation of energetic heavy ions on digital pulse shape analysis with silicon detectors

29 janvier 2013

The next generation of 4π detector arrays for heavy ion studies will largely use Pulse Shape Analysis to push the performance of silicon detectors with respect to ion identification. Energy resolution and pulse shape identification capabilities of silicon detectors under prolonged irradiation by (...)

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[in2p3-00778551] Isospin transport in 84Kr + 112,124Sn collisions at Fermi energies

21 janvier 2013

Isotopically resolved fragments with Z =20 have been studied with high resolution telescopes in a test run for the FAZIA collaboration. The fragments were produced by the collision of a 84Kr beam at 35 MeV/nucleon with a n-rich (124Sn) and a n-poor (112Sn) target. The fragments, detected close (...)

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[in2p3-00772111] A single-chip telescope for heavy-ion identification

10 janvier 2013

A ΔE-E telescope exploiting a single silicon chip for both ΔE measurement and scintillation light collection has been tested. It is a Si-CsI(Tl) telescope tailored for mass identification of light charged particles and intermediate mass fragments. A procedure based on two different shaping (...)

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[in2p3-00753651] Comparison of charged particle identification using pulse shape discrimination and ΔE−E methods between front and rear side injection in silicon detectors

22 novembre 2012

The response of silicon-silicon-CsI(Tl) telescopes, developed within the FAZIA collaboration, to fragments produced in nuclear reactions 84Kr+120-124Sn at 35 A MeV, has been used to study ion identification methods. Two techniques are considered for the identification of the nuclear products in (...)

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Nuclear multifragmentation time-scale and fluctuations of largest fragment size

1er octobre 2012

Distributions of the largest fragment charge, Zmax, in multifragmentation reactions around the Fermi energy can be decomposed into a sum of a Gaussian and a Gumbel distribution, whereas at much higher or lower energies one or the other distribution is asymptotically dominant. We demonstrate the (...)

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[in2p3-00736381] New isospin effects in central heavy-ion collisions at Fermi energies

28 septembre 2012

Isospin e ffects on multifragmentation properties were studied thanks to nuclear collisions between di fferent isotopes of xenon beams and tin targets. It is shown that, in central collisions leading to multifragmentation, the mean number of fragments and their mean kinetic energy increase with (...)

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Chemistry of nuclear particle production in 32 A MeV 136,124Xe+124,112Sn reactions and nuclear symmetry energy

11 septembre 2012

Nuclear particle production from peripheral to central events is presented. N/Z gradient between projectile and target is studied using the fact that two reactions have the same projectile+target N/Z and so the same neutron to proton ratio for the combined system and the impact parameter size (...)

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Status and performances of the FAZIA project

31 août 2012

FAZIA is designed for detailed studies of the isospin degree of freedom, extending to the limits the isotopic identification of charged products from nuclear collisions when using silicon detectors and CsI(Tl) scintillators. We show that the FAZIA telescopes give isotopic identification up to (...)

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The behaviour of constrained caloric curves as ultimate signature of a phase transition for hot nuclei

25 juillet 2012

Simulations based on experimental data obtained from multifragmenting quasifused nuclei produced in central 129Xe + natSn collisions have been used to deduce event by event freeze-out properties on the thermal excitation energy range 4-12 AMeV. From these properties and temperatures deduced (...)

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[in2p3-00704236] Correlations between emission timescale of fragments and isospin dynamics in $^{124}$Sn+$^{64}$Ni and $^{112}$Sn+$^{58}$Ni reactions at 35 AMeV

5 juin 2012

We present a new experimental method to correlate the isotopic composition of intermediate mass fragments (IMF) emitted at mid-rapidity in semi-peripheral collisions with the emission timescale: IMFs emitted in the early stage of the reaction show larger values of $$ isospin asymmetry, stronger (...)

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Asymmetric fission in 78Kr+40Ca reactions at 5.5 MeV/nucleon

14 février 2012

Decay modes of excited nuclei formed in the 78,82Kr+40Ca reactions at 5.5 AMeV are investigated by means of exclusive measurements using the INDRA detector at GANIL. Light‐charged particles in coincidence with fragments show that, in the mechanism of asymmetric fission, the light partner (with (...)

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Particle identification using the (DELTA)E-E technique and pulse shape discrimination with the silicon detectors of the FAZIA project

4 janvier 2012

The response of silicon-silicon-CsI(Tl) and silicon-CsI(Tl) telescopes to fragments produced in nuclear interactions has been studied. The telescopes were developed within the FAZIA collaboration. The capabilities of two methods are compared: (a) the standard ΔE-E technique and (b) the digital (...)

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[in2p3-00656422] Particle identification using the (DELTA)E-E technique and pulse shape discrimination with the silicon detectors of the FAZIA project

4 janvier 2012

The response of silicon-silicon-CsI(Tl) and silicon-CsI(Tl) telescopes to fragments produced in nuclear interactions has been studied. The telescopes were developed within the FAZIA collaboration. The capabilities of two methods are compared: (a) the standard ΔE-E technique and (b) the digital (...)

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Recent results from INDRA

27 octobre 2011

We present an overview of recent results & advances within the INDRA collaboration

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Decay of excited nuclei produced in $^{78,82}$Kr + $^{40}$Ca reactions at 5.5 MeV/nucleon

20 avril 2011

Decay modes of excited nuclei are investigated in $^78,82$Kr + $^40$Ca reactions at 5.5 MeV/nucleon. Charged products were measured by means of the $4\pi$ INDRA array. Kinetic-energy spectra and angular distributions of fragments with atomic number 3 $\le Z \le$ 28 indicate a high degree of (...)

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[in2p3-00587476] Decay of excited nuclei produced in $^{78,82}$Kr + $^{40}$Ca reactions at 5.5 MeV/nucleon

20 avril 2011

Decay modes of excited nuclei are investigated in $^78,82$Kr + $^40$Ca reactions at 5.5 MeV/nucleon. Charged products were measured by means of the $4\pi$ INDRA array. Kinetic-energy spectra and angular distributions of fragments with atomic number 3 $\le Z \le$ 28 indicate a high degree of (...)

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Description of current pulses induced by heavy ions in silicon detectors (II)

20 avril 2011

Current pulses induced in a silicon detector by 10 different heavy ion species at known energies around 10 AMeV have been sampled in time at high frequency. Their individual average shapes are quite well reproduced by a fit procedure based on our recent charge carrier collection treatment which (...)

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[in2p3-00587352] Description of current pulses induced by heavy ions in silicon detectors (II)

20 avril 2011

Current pulses induced in a silicon detector by 10 different heavy ion species at known energies around 10 AMeV have been sampled in time at high frequency. Their individual average shapes are quite well reproduced by a fit procedure based on our recent charge carrier collection treatment which (...)

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Test of FAZIA prototypes at LNS.

31 janvier 2011

The response of a few silicon-silicon-CsI(Tl) and silicon-silicon telescopes with high quality detectors developed within the FAZIA collaboration [1] is tested in this work. The silicon detectors were manufactured from “random cut” wafers to avoid channeling effects and are characterized by a (...)

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[in2p3-00560905] Test of FAZIA prototypes at LNS.

31 janvier 2011

The response of a few silicon-silicon-CsI(Tl) and silicon-silicon telescopes with high quality detectors developed within the FAZIA collaboration [1] is tested in this work. The silicon detectors were manufactured from “random cut” wafers to avoid channeling effects and are characterized by a (...)

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Hierarchy effects in light framents at mid-velocity emission

31 janvier 2011

Intermediate mass fragments (IMF) emitted with multiplicity MIMF ≥ 3 at mid-velocity in semi-central reactions induced by 124Sn projectile (35 A.MeV) on 64Ni target have been studied. The results show a clear correlation between the fragment sizes and the corresponding transverse velocities. We (...)

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[in2p3-00560901] Hierarchy effects in light framents at mid-velocity emission

31 janvier 2011

Intermediate mass fragments (IMF) emitted with multiplicity MIMF ≥ 3 at mid-velocity in semi-central reactions induced by 124Sn projectile (35 A.MeV) on 64Ni target have been studied. The results show a clear correlation between the fragment sizes and the corresponding transverse velocities. We (...)

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New scalings in nuclear fragmentation

1er septembre 2010

Fragment partitions of fragmenting hot nuclei produced in central and semiperipheral collisions have been compared in the excitation energy region 4-10 MeV per nucleon where radial collective expansion takes place. It is shown that, for a given total excitation energy per nucleon, the amount of (...)

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New scalings in nuclear fragmentation

1er septembre 2010

Fragment partitions of fragmenting hot nuclei produced in central and semiperipheral collisions have been compared in the excitation energy region 4-10 MeV per nucleon where radial collective expansion takes place. It is shown that, for a given total excitation energy per nucleon, the amount of (...)

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Strong enhancement of dynamical emission of heavy fragments in the neutron-rich 124Sn+64Ni reaction at 35A MeV

22 juin 2010

A quantitative comparison is made between the absolute cross sections associated with statistical and dynamical emission of heavy fragments in the 124Sn+64Ni and 112Sn+58Ni collisions experimentally investigated at 35A MeV beam energy using the multidetector CHIMERA. The result shows that the (...)

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[in2p3-00494236] Strong enhancement of dynamical emission of heavy fragments in the neutron-rich 124Sn+64Ni reaction at 35A MeV

22 juin 2010

A quantitative comparison is made between the absolute cross sections associated with statistical and dynamical emission of heavy fragments in the 124Sn+64Ni and 112Sn+58Ni collisions experimentally investigated at 35A MeV beam energy using the multidetector CHIMERA. The result shows that the (...)

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Study of Nuclear Stopping in Central Collisions at Intermediate Energies

22 juin 2010

Nuclear stopping has been investigated in central nuclear collisions at intermediate energies by analyzing kinematically complete events recorded with the help of the 4π multidetector INDRA for a large variety of symmetric systems. It is found that the mean isotropy ratio defined as the ratio of (...)

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[in2p3-00494230] Study of Nuclear Stopping in Central Collisions at Intermediate Energies

22 juin 2010

Nuclear stopping has been investigated in central nuclear collisions at intermediate energies by analyzing kinematically complete events recorded with the help of the 4π multidetector INDRA for a large variety of symmetric systems. It is found that the mean isotropy ratio defined as the ratio of (...)

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Influence Of The Neutron Richness On Binary Decays

9 mars 2010

The influence of the neutron richness on binary decays is investigated in 78,82Kr+ 40Ca reactions at 5.5 MeV/A incident energy. Kinetic energy distributions and angular distributions of fragments with atomic number 6 ≤ Z ≤ 28 were measured using the 4π-INDRA array. Global features are compatible (...)

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Influence Of The Neutron Richness On Binary Decays

9 mars 2010

The influence of the neutron richness on binary decays is investigated in 78,82Kr+ 40Ca reactions at 5.5 MeV/A incident energy. Kinetic energy distributions and angular distributions of fragments with atomic number 6 ≤ Z ≤ 28 were measured using the 4π-INDRA array. Global features are compatible (...)

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Multifragmentation and phase transition for hot nuclei

5 mars 2010

Recent important progress on the knowledge of multifragmentation and phase transition for hot nuclei, thanks to the high detection quality of the INDRA array, is reported. It concerns i) the radial collective energies involved in hot fragmenting nuclei/sources produced in central and semi- (...)

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Multifragmentation and phase transition for hot nuclei

5 mars 2010

Recent important progress on the knowledge of multifragmentation and phase transition for hot nuclei, thanks to the high detection quality of the INDRA array, is reported. It concerns i) the radial collective energies involved in hot fragmenting nuclei/sources produced in central and semi- (...)

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THE PROMINENT ROLE OF THE HEAVIEST FRAGMENT IN MULTIFRAGMENTATION AND PHASE TRANSITION FOR HOT NUCLEI

5 mars 2010

The role played by the heaviest fragment in partitions of multifragmenting hot nuclei is emphasized. Its size/charge distribution (mean value, fluctuations and shape) gives information on properties of fragmenting nuclei and on the associated phase (...)

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THE PROMINENT ROLE OF THE HEAVIEST FRAGMENT IN MULTIFRAGMENTATION AND PHASE TRANSITION FOR HOT NUCLEI

5 mars 2010

The role played by the heaviest fragment in partitions of multifragmenting hot nuclei is emphasized. Its size/charge distribution (mean value, fluctuations and shape) gives information on properties of fragmenting nuclei and on the associated phase (...)

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Isospin diffusion in 58Ni-induced reactions at intermediate energies

4 mars 2010

Isospin diffusion is probed as a function of the dissipated energy by studying two systems $^58$Ni+$^58$Ni and $^58$Ni+$^197$Au, over the incident energy range 52-74\AM. Experimental data are compared with the results of a microscopic transport model with two different parameterizations of the (...)

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Isospin diffusion in 58Ni-induced reactions at intermediate energies

4 mars 2010

Isospin diffusion is probed as a function of the dissipated energy by studying two systems $^58$Ni+$^58$Ni and $^58$Ni+$^197$Au, over the incident energy range 52-74\AM. Experimental data are compared with the results of a microscopic transport model with two different parameterizations of the (...)

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Multifragmentation and phase transition for hot nuclei: recent progress

23 février 2010

Recent important progress on the knowledge of multifragmentation and phase transition for hot nuclei, thanks to the high detection quality of the INDRA array, is reported. It concerns i) the radial collective energies involved in hot fragmenting nuclei/sources produced in central and (...)

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Multifragmentation and phase transition for hot nuclei: recent progress

23 février 2010

Recent important progress on the knowledge of multifragmentation and phase transition for hot nuclei, thanks to the high detection quality of the INDRA array, is reported. It concerns i) the radial collective energies involved in hot fragmenting nuclei/sources produced in central and (...)

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Isospin effects in projectile-like dynamical fission for 112,124Sn+58,64Ni reactions at 35 AMeV

16 novembre 2009

A quantitative comparison regarding absolute cross sections associated to Statistical and Dynamical Fission processes in the 124Sn+64Ni and 112Sn+58Ni collisions experimentally investigated at 35 AMeV beam energy using multi-detector CHIMERA is presented. It results that Dynamical Fission (...)

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Isospin effects in projectile-like dynamical fission for 112,124Sn+58,64Ni reactions at 35 AMeV

16 novembre 2009

A quantitative comparison regarding absolute cross sections associated to Statistical and Dynamical Fission processes in the 124Sn+64Ni and 112Sn+58Ni collisions experimentally investigated at 35 AMeV beam energy using multi-detector CHIMERA is presented. It results that Dynamical Fission (...)

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Bimodal behavior of the heaviest fragment distribution in projectile fragmentation

9 juillet 2009

The charge distribution of the heaviest fragment detected in the decay of quasi-projectiles produced in intermediate energy heavy-ion collisions has been observed to be bimodal. This feature is expected as a generic signal of phase transition in non-extensive systems. In this paper we present (...)

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Bimodal behavior of the heaviest fragment distribution in projectile fragmentation

9 juillet 2009

The charge distribution of the heaviest fragment detected in the decay of quasi-projectiles produced in intermediate energy heavy-ion collisions has been observed to be bimodal. This feature is expected as a generic signal of phase transition in non-extensive systems. In this paper we present (...)

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Influence of crystal-orientation effects on pulse-shape-based identification of heavy-ions stopped in silicon detectors

19 juin 2009

Current and charge signals have been collected for Se ions at 408 MeV, S at 160 MeV and Ni at 703 MeV, all stopped in silicon detectors. Some detectors were cut 0ring operator off the View the MathML source axis and some off the View the MathML source axis. Important effects on the shape of the (...)

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[in2p3-00397120] Influence of crystal-orientation effects on pulse-shape-based identification of heavy-ions stopped in silicon detectors

19 juin 2009

Current and charge signals have been collected for Se ions at 408 MeV, S at 160 MeV and Ni at 703 MeV, all stopped in silicon detectors. Some detectors were cut 0ring operator off the View the MathML source axis and some off the View the MathML source axis. Important effects on the shape of the (...)

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Dynamical Signals in Fragmentation Reactions: Time Scale Determination from Three Fragments Correlations by Using the 4$\pi$ CHIMERA Multidetector

15 mai 2009

For fragments emitted in the reactions 124Sn + 64Ni and 112Sn + 58Ni at 35 AMeV, isotopic composition and velocity correlations have been studied as a function of the centrality of the collision, using the 4\pi Chimera multidetector. We have investigated the time scale for fragments formation, (...)

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Dynamical Signals in Fragmentation Reactions: Time Scale Determination from Three Fragments Correlations by Using the 4$\pi$ CHIMERA Multidetector

15 mai 2009

For fragments emitted in the reactions 124Sn + 64Ni and 112Sn + 58Ni at 35 AMeV, isotopic composition and velocity correlations have been studied as a function of the centrality of the collision, using the 4\pi Chimera multidetector. We have investigated the time scale for fragments formation, (...)

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Multifragmentation and spinodal decomposition of finite nuclear systems

28 avril 2009

A bulk effect in multifragmentation of very heavy fused systems has been experimentally evidenced. Such an effect is very well reproduced by a complete dynamical simulation of collisions in which multifragmentation occurs through the growth of density fluctuations in the unstable spinodal (...)

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Multifragmentation and spinodal decomposition of finite nuclear systems

28 avril 2009

A bulk effect in multifragmentation of very heavy fused systems has been experimentally evidenced. Such an effect is very well reproduced by a complete dynamical simulation of collisions in which multifragmentation occurs through the growth of density fluctuations in the unstable spinodal (...)

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Physics with the CHIMERA detector at LNS CATANIA methodology-experimental results - Future development

28 avril 2009

he new Charged Heavy Ion Mass and Energy Resolving Array CHIMERA was designed to significantly contribute to Multifragmentation studies in Heavy Ion collisions at Fermi energy (20A.MeV < E < 100A.MeV). The multi detector is presently being set up at LNS in Catania. On April 2000 the (...)

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Physics with the CHIMERA detector at LNS CATANIA methodology-experimental results - Future development

28 avril 2009

he new Charged Heavy Ion Mass and Energy Resolving Array CHIMERA was designed to significantly contribute to Multifragmentation studies in Heavy Ion collisions at Fermi energy (20A.MeV < E < 100A.MeV). The multi detector is presently being set up at LNS in Catania. On April 2000 the (...)

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New digital techniques applied to A and Z identification using pulse shape discrimination of silicon detector current signals

27 avril 2009

Extending pulse shape discrimination (PSD) to digitized signals is one of the most promising methods to identify particles stopped in a detector. Using the CIME accelerator in the GANIL laboratory, a measurement campaign was done to collect data corresponding to different charges, masses and (...)

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[in2p3-00363510] New digital techniques applied to A and Z identification using pulse shape discrimination of silicon detector current signals

27 avril 2009

Extending pulse shape discrimination (PSD) to digitized signals is one of the most promising methods to identify particles stopped in a detector. Using the CIME accelerator in the GANIL laboratory, a measurement campaign was done to collect data corresponding to different charges, masses and (...)

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Influence of the N/Z ratio on Disintegration Modes of Compound Nuclei

16 avril 2009

Investigations into the role of the N/Z ratio on the decay modes of compound nuclei are presented. Characteristics of fragments with atomic number 6$\leq$Z$\leq$28 and light charged particles emitted in 78,82Kr+40Ca at 5.5 MeV/A reactions were measured at the GANIL facility using the (...)

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Influence of the N/Z ratio on Disintegration Modes of Compound Nuclei

16 avril 2009

Investigations into the role of the N/Z ratio on the decay modes of compound nuclei are presented. Characteristics of fragments with atomic number 6$\leq$Z$\leq$28 and light charged particles emitted in 78,82Kr+40Ca at 5.5 MeV/A reactions were measured at the GANIL facility using the (...)

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Isospin diffusion in semi-peripheral $^{58}Ni$+$^{197}Au$ collisions at intermediate energies (I): Experimental results

15 décembre 2008

Isospin diffusion in semi-peripheral collisions is probed as a function of the dissipated energy by studying two systems $^58Ni$+$^58Ni$ and $^58Ni$+$^197Au$, over the incident energy range 52-74\AM. A close examination of the multiplicities of light products in the forward part of phase space (...)

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Isospin diffusion in semi-peripheral $^{58}Ni$+$^{197}Au$ collisions at intermediate energies (I): Experimental results

15 décembre 2008

Isospin diffusion in semi-peripheral collisions is probed as a function of the dissipated energy by studying two systems $^58Ni$+$^58Ni$ and $^58Ni$+$^197Au$, over the incident energy range 52-74\AM. A close examination of the multiplicities of light products in the forward part of phase space (...)

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Fragment properties of fragmenting heavy nuclei produced in central and semi-peripheral collisions.

31 octobre 2008

Fragment properties of hot fragmenting sources of similar sizes produced in central and semi-peripheral collisions are compared in the excitation energy range 5-10 AMeV. For semi-peripheral collisions a method for selecting compact quasi-projectiles sources in velocity space similar to those of (...)

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Fragment properties of fragmenting heavy nuclei produced in central and semi-peripheral collisions.

31 octobre 2008

Fragment properties of hot fragmenting sources of similar sizes produced in central and semi-peripheral collisions are compared in the excitation energy range 5-10 AMeV. For semi-peripheral collisions a method for selecting compact quasi-projectiles sources in velocity space similar to those of (...)

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N/Z influence on disintegration modes of compound nuclei.

10 octobre 2008

Investigations on the influence of the neutron enrichment on the decay channels of excited nuclei are presented. Characteristics of fragments with charge 6 Z 28 emitted in 78,82Kr+40Ca at 5.5 MeV/A reactions were measured at the GANIL facility. Data are compatible with an emission process from (...)

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N/Z influence on disintegration modes of compound nuclei.

10 octobre 2008

Investigations on the influence of the neutron enrichment on the decay channels of excited nuclei are presented. Characteristics of fragments with charge 6 Z 28 emitted in 78,82Kr+40Ca at 5.5 MeV/A reactions were measured at the GANIL facility. Data are compatible with an emission process from (...)

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Multi-particle correlation function to study short-lived nuclei

8 octobre 2008

Unstable 10C nuclei are produced as quasi-projectiles in 12C+24Mg collisions at E/A = 53 and 95 MeV. The decay of their short-lived states is studied with the INDRA multidetector array via multi-particle correlation functions. The obtained results show that heavy-ion collisions can be used as a (...)

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[in2p3-00310864] Multi-particle correlation function to study short-lived nuclei

8 octobre 2008

Unstable 10C nuclei are produced as quasi-projectiles in 12C+24Mg collisions at E/A = 53 and 95 MeV. The decay of their short-lived states is studied with the INDRA multidetector array via multi-particle correlation functions. The obtained results show that heavy-ion collisions can be used as a (...)

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Influence of neutron enrichment on disintegration modes of compound nuclei

22 août 2008

Cross sections, kinetic energy and angular distributions of fragments with charge 6$\le$Z$\le$28 emitted in $^78,82$Kr+$^40$C at 5.5 MeV/A reactions were measured at the GANIL facility using the INDRA apparatus. This experiment aims to investigate the influence of the neutron enrichment on the (...)

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Influence of neutron enrichment on disintegration modes of compound nuclei

22 août 2008

Cross sections, kinetic energy and angular distributions of fragments with charge 6$\le$Z$\le$28 emitted in $^78,82$Kr+$^40$C at 5.5 MeV/A reactions were measured at the GANIL facility using the INDRA apparatus. This experiment aims to investigate the influence of the neutron enrichment on the (...)

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Freeze-out properties of multifragmentation events

30 juin 2008

Freeze-out properties of multifragmentation events produced in central 129Xe+natSn collisions at different beam energies (32, 39, 45 and 50 AMeV) were estimated by means of a simulation based on the experimental data collected by the 4π INDRA multidetector. A rapid increase (between 32 and 45 (...)

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[in2p3-00291789] Freeze-out properties of multifragmentation events

30 juin 2008

Freeze-out properties of multifragmentation events produced in central 129Xe+natSn collisions at different beam energies (32, 39, 45 and 50 AMeV) were estimated by means of a simulation based on the experimental data collected by the 4π INDRA multidetector. A rapid increase (between 32 and 45 (...)

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Multifragmentation threshold in $^{93}Nb+${nat}Mg collisions at 30 MeV/nucleon

7 mai 2008

We analyzed the $^93Nb$ on $^natMg$ reaction at $30$ MeV/nucleon in the aim of disentangling binary sequential decay and multifragmentation decay close to the energy threshold, i.e. $\simeq 3$ MeV/nucleon. Using the backtracing technique applied to the statistical models GEMINI and SMM we (...)

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Multifragmentation threshold in $^{93}Nb+${nat}Mg collisions at 30 MeV/nucleon

7 mai 2008

We analyzed the $^93Nb$ on $^natMg$ reaction at $30$ MeV/nucleon in the aim of disentangling binary sequential decay and multifragmentation decay close to the energy threshold, i.e. $\simeq 3$ MeV/nucleon. Using the backtracing technique applied to the statistical models GEMINI and SMM we (...)

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Centrality dependence of isospin effect signatures in $^{124}$Sn+$^{64}$Ni and $^{112}$Sn+$^{58}$Ni reactions

23 janvier 2008

Signatures of isospin effects were investigated for neutron-rich (124Sn+64Ni) and neutron-poor (112Sn+58Ni) systems at 35 MeV/nucleon for noncentral collisions. The centrality dependence of these signatures was tested for several impact parameter estimators. Our main observations are (i) the (...)

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[in2p3-00213448] Centrality dependence of isospin effect signatures in $^{124}$Sn+$^{64}$Ni and $^{112}$Sn+$^{58}$Ni reactions

23 janvier 2008

Signatures of isospin effects were investigated for neutron-rich (124Sn+64Ni) and neutron-poor (112Sn+58Ni) systems at 35 MeV/nucleon for noncentral collisions. The centrality dependence of these signatures was tested for several impact parameter estimators. Our main observations are (i) the (...)

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R & D FAZIA : une nouvelle méthode d'identification des ions pour la physique avec les noyaux radioactifs

6 décembre 2007

Un programme de Recherche et Développement (R-D FAZIA) dédié à de nouveaux concepts d'identification en Masse (A) et Charge (Z) des produits de réactions nucléaires a été entrepris depuis plusieurs années et fait l'objet d'un programme soutenu par l'Agence Nationale de la Recherche pour 2006 et 2007. (...)

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R & D FAZIA : une nouvelle méthode d'identification des ions pour la physique avec les noyaux radioactifs

6 décembre 2007

Un programme de Recherche et Développement (R-D FAZIA) dédié à de nouveaux concepts d'identification en Masse (A) et Charge (Z) des produits de réactions nucléaires a été entrepris depuis plusieurs années et fait l'objet d'un programme soutenu par l'Agence Nationale de la Recherche pour 2006 et 2007. (...)

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Source shape determination with directional fragment-fragment velocity correlations

12 novembre 2007

Correlation functions, constructed from directional projections of the relative velocities of fragments, are used to determine the shape of the breakup volume in coordinate space. For central collisions of 129Xe + natSn at 50 MeV per nucleon incident energy, measured with the 4pi multi-detector (...)

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[in2p3-00186887] Source shape determination with directional fragment-fragment velocity correlations

12 novembre 2007

Correlation functions, constructed from directional projections of the relative velocities of fragments, are used to determine the shape of the breakup volume in coordinate space. For central collisions of 129Xe + natSn at 50 MeV per nucleon incident energy, measured with the 4pi multi-detector (...)

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Signals of dynamical multifragmentation as seen by CHIMERA detector

4 octobre 2007

Using 4[PI] CHIMERA multi detector we have studied the event by event impact parameter depen- dence of the fragment-fragment relative velocities correlation for the three heaviest fragments which were selected according to their charge and parallel velocity along the beam (...)

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Signals of dynamical multifragmentation as seen by CHIMERA detector

4 octobre 2007

Using 4[PI] CHIMERA multi detector we have studied the event by event impact parameter depen- dence of the fragment-fragment relative velocities correlation for the three heaviest fragments which were selected according to their charge and parallel velocity along the beam (...)

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Yield scaling, size hierarchy and fluctuations of observables in fragmentation of excited heavy nuclei

13 septembre 2007

Multifragmentation properties measured with INDRA are studied for single sources produced in Xe+Sn reactions in the incident energy range 32-50 A MeV and quasiprojectiles from Au+Au collisions at 80 A MeV. A comparison for both types of sources is presented concerning Fisher scaling, Zipf law, (...)

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Yield scaling, size hierarchy and fluctuations of observables in fragmentation of excited heavy nuclei

13 septembre 2007

Multifragmentation properties measured with INDRA are studied for single sources produced in Xe+Sn reactions in the incident energy range 32-50 A MeV and quasiprojectiles from Au+Au collisions at 80 A MeV. A comparison for both types of sources is presented concerning Fisher scaling, Zipf law, (...)

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Dynamical multi-breakup processes in the $^{124}$Sn+$^{64}$Ni system at 35 MeV/nucleon

5 septembre 2007

Multi-breakup processes for the $^124$Sn+$^64$Ni system at 35 MeV/nucleon have been studied with the forward part of the CHIMERA detector. An extensive comparison between experimental data corresponding to almost complete ternary events and constrained molecular dynamics (CoMD-II) calculations (...)

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[in2p3-00169801] Dynamical multi-breakup processes in the $^{124}$Sn+$^{64}$Ni system at 35 MeV/nucleon

5 septembre 2007

Multi-breakup processes for the $^124$Sn+$^64$Ni system at 35 MeV/nucleon have been studied with the forward part of the CHIMERA detector. An extensive comparison between experimental data corresponding to almost complete ternary events and constrained molecular dynamics (CoMD-II) calculations (...)

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A preliminary study on ternary fission in the $^{124}$Sn + $^{64}$Ni reaction at 35 MeV/A

22 août 2007

The projectile-like fragmentation in the $^124$Sn + $^64$Ni reaction at 35 MeV/A is investigated in the frame of ternary emission. With a very selective analysis of our data, we found consistency of our results with the concept of a ternary emission mechanism in heavy ions collisions at (...)

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A preliminary study on ternary fission in the $^{124}$Sn + $^{64}$Ni reaction at 35 MeV/A

22 août 2007

The projectile-like fragmentation in the $^124$Sn + $^64$Ni reaction at 35 MeV/A is investigated in the frame of ternary emission. With a very selective analysis of our data, we found consistency of our results with the concept of a ternary emission mechanism in heavy ions collisions at (...)

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Universal fluctuations: a new approach to the study of phase transitions in intermediate energy heavy ion collisions

15 janvier 2007

The universal theory of order parameter fluctuations (D-scaling laws) is applied to a wide range of intermediate energy heavy-ion collision data obtained with INDRA. This systematic study confirms that the observed fragment production is compatible with aggregation scenarios for in- or (...)

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Universal fluctuations: a new approach to the study of phase transitions in intermediate energy heavy ion collisions

15 janvier 2007

The universal theory of order parameter fluctuations (D-scaling laws) is applied to a wide range of intermediate energy heavy-ion collision data obtained with INDRA. This systematic study confirms that the observed fragment production is compatible with aggregation scenarios for in- or (...)

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Directed and elliptic flow in $^{197}$Au+$^{197}$Au at intermediate energies

5 janvier 2007

Directed and elliptic flow for the $^197$Au+$^197$Au system at incident energies between 40 and 150 MeV per nucleon has been measured using the INDRA 4$\pi$ multi-detector. For semi-central collisions, the excitation function of elliptic flow shows a transition from in-plane to out-of-plane (...)

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[in2p3-00122885] Directed and elliptic flow in $^{197}$Au+$^{197}$Au at intermediate energies

5 janvier 2007

Directed and elliptic flow for the $^197$Au+$^197$Au system at incident energies between 40 and 150 MeV per nucleon has been measured using the INDRA 4$\pi$ multi-detector. For semi-central collisions, the excitation function of elliptic flow shows a transition from in-plane to out-of-plane (...)

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Evaluation of excitation energy and spin from light charged particles multiplicities in heavy-ion collisions

5 janvier 2007

A simple procedure for evaluating the excitation energy and the spin transfer in heavy-ion dissipative collisions is proposed. It is based on a prediction of the GEMINI evaporation code : for a nucleus with a given excitation energy, the average number of emitted protons decreases with (...)

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Evaluation of excitation energy and spin from light charged particles multiplicities in heavy-ion collisions

5 janvier 2007

A simple procedure for evaluating the excitation energy and the spin transfer in heavy-ion dissipative collisions is proposed. It is based on a prediction of the GEMINI evaporation code : for a nucleus with a given excitation energy, the average number of emitted protons decreases with (...)

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Evolution of the fusion cross-section for light systems at intermediate energies

5 janvier 2007

Ar + Ni and Ni + Ni collisions are investigated between 32 and around 100A MeV incident energy with the 4π multidetector INDRA. Fusion cross-sections are found to decrease from ˜ 180mb at 32A MeV to zero above 50A MeV. Other experimental results, for light systems, are compared. Moreover, (...)

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[in2p3-00072508] Evolution of the fusion cross-section for light systems at intermediate energies

5 janvier 2007

Ar + Ni and Ni + Ni collisions are investigated between 32 and around 100A MeV incident energy with the 4π multidetector INDRA. Fusion cross-sections are found to decrease from ˜ 180mb at 32A MeV to zero above 50A MeV. Other experimental results, for light systems, are compared. Moreover, (...)

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Effect of the intermediate velocity emissions on the quasi-projectile properties for the Ar + Ni system at 95 A.MeV

4 janvier 2007

The quasi-projectile (QP) properties are investigated in the Ar+Ni collisions at 95 A.MeV taking into account the intermediate velocity emission. Indeed, in this reaction, between 52 and 95 A.MeV bombarding energies, the number of particles emitted in the intermediate velocity region is related (...)

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Effect of the intermediate velocity emissions on the quasi-projectile properties for the Ar + Ni system at 95 A.MeV

4 janvier 2007

The quasi-projectile (QP) properties are investigated in the Ar+Ni collisions at 95 A.MeV taking into account the intermediate velocity emission. Indeed, in this reaction, between 52 and 95 A.MeV bombarding energies, the number of particles emitted in the intermediate velocity region is related (...)

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Comparisons of statistical multifragmentation and evaporation models for heavy-ion collisions

6 décembre 2006

The results from ten statistical multifragmentation models have been compared with each other using selected experimental observables. Even though details in any single observable may differ, the general trends among models are similar. Thus, these models and similar ones are very good in (...)

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Calorimetry

5 décembre 2006

Methods for determining the heat content E */A of hot nuclei formed in energetic nuclear reactions are discussed. The primary factors involved in converting raw data into thermal physics distributions include: 1) design of the detector array, 2) constraints imposed by the physics of the (...)

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Multifragmentation of a very heavy nuclear system (I): selection of a single-source events

10 juillet 2006

A sample of `single-source' events, compatible with the multifragmentation of very heavy fused systems, are isolated among well-measured $^155$Gd+$^nat$U 36AMeV reactions by examining the evolution of the kinematics of fragments with Z>=5 as a function of the dissipated energy and loss of (...)

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Multifragmentation of a very heavy nuclear system (II) bulk properties and spinodal decomposition

10 juillet 2006

The properties of fragments and light charged particles emitted in multifragmentation of single sources formed in central 36AMeV Gd+U collisions are reviewed. Most of the products are isotropically distributed in the reaction c.m. Fragment kinetic energies reveal the onset of radial collective (...)

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Response of CsI(Tl) scintillators over a large range in energy and atomic number of ions (Part I) : recombination and $\delta$-electrons

7 juillet 2006

A simple formalism describing the light response of CsI(Tl) to heavy ions, which quantifies the luminescence and the quenching in terms of the competition between radiative transitions following the carrier trapping at the Tl activator sites and the electron-hole recombination, is proposed. The (...)

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Bimodality: a possible experimental signature of the liquid-gas phase transition of nuclear matter

7 février 2006

We have observed a bimodal behaviour of the distribution of the asymmetry between the charges of the two heaviest products resulting from the decay of the quasi-projectile released in binary Xe+Sn and Au+Au collisions from 60 to 100 MeV/u. Event sorting has been achieved through the transverse (...)

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Liquid-Gas Coexistence Region in Central Xe+Sn Reactions

18 octobre 2005

Charge partitions and distributions of fragments emitted in multifragmentation of fused systems produced in central collisions are studied over the incident energy range 32-50 MeV per nucleon. Most of the charged products are well identified thanks to the high performances of the INDRA 4pi (...)

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Evidence for Spinodal Decomposition in Nuclear Multifragmentation

18 octobre 2005

Multifragmentation of a ``fused system\'\' was observed for central collisions between 32 MeV/nucleon 129Xe and natSn. Most of the resulting charged products were well identified thanks to the high performances of the INDRA 4pi array. Experimental higher-order charge correlations for fragments (...)

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Estimate of average freeze-out volume in multifragmentation events

5 septembre 2005

An estimate of the average freeze-out volume for multifragmentation events is presented. Values of volumes are obtained by means of a simulation using the experimental charged product partitions measured by the 4pi multidetector INDRA for 129Xe central collisions on Sn at 32 AMeV incident (...)

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Multifragmentation of very heavy nuclear systems (III): fragment velocity correlations and event topology at freeze-out.

26 août 2005

Kinetic energy spectra and fragment velocity correlations, simulated by means of stochastic mean-field calculations, are successfully confronted with experimental data for single multifragmenting sources prepared at the same excitation energy per nucleon in 32 AMeV 129Xe+natSn and 36 AMeV (...)

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Evolution of Fragment Distributions and Reaction Mechanisms for the Ar+Ni System from 32 to 95 A.MeV

24 juin 2005

Within the framework of flow and multifragmentation study, the 36Ar+58Ni experiment has been performed at seven incident energies from 32 to 95 A.MeV with the INDRA detector at GANIL. After a brief description of the experimental set-up, the main trends as well as the evolution of fragment (...)

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Bimodality and negative heat capacity in multifragmentation

24 mars 2005

This contribution addresses the question of the possible link between multifragmentation and the liquid-gas phase transition of nuclear matter. Bimodality seems to be a robust signal of this link in the sense that theoretical calculations indicate that it is preserved even if a sizeable (...)

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A panorama of phase transition signals and influence of collision-induced correlations

24 mars 2005

The presented results will show the richness of nuclear heavy-ion physics where data are accumulated as a succession of independent events. The different reaction mechanisms can provide for 39 A.MeV Ta+Au, 40 and 80 A.MeV Au+Au peripheral collisions a set of data almost free of entrance channel (...)

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A study of nuclear stopping in central symmetric nuclear collisions at intermediate energies

14 mars 2005

Nuclear stopping has been investigated in central symmetric nuclear collisions at intermediate energies. Firstly, it is found that the isotropy ratio, Riso, reaches a minimum near the Fermi energy and saturates or slowly increases depending on the mass of the system as the beam energy (...)

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Isotopic Scaling and the Symmetry Energy in Spectator Fragmentation

17 février 2005

Isotopic effects in the fragmentation of excited target residues following collisions of $^12$C on $^112,124$Sn at incident energies of 300 and 600 MeV per nucleon were studied with the INDRA 4$\pi$ detector. The measured yield ratios for light particles and fragments with atomic number $Z (...)

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Directed and elliptic flow in $^{197}$Au+$^{197}$Au at intermediate energies

11 février 2005

Directed and elliptic flow for the Au + Au system at incident energies between 40 and 150 MeV per nucleon has been measured using the INDRA 4 pi multi-detector. For semi-central collisions, the elliptic flow of Z <= 2 particles switches from in-plane to out-of-plane enhancement at around (...)

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Liquid-gas phase transition in hot nuclei: correlation between dynamical and thermodynamical signals

11 janvier 2005

The dynamics and thermodynamics of phase transition in hot nuclei are studied through experimental results on multifragmentation of heavy systems (A$geq$200) formed in central heavy ion collisions. Different signals indicative of a phase transition studied in the INDRA collaboration are (...)

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Correlations between signals of the liquid-gas phase transition in nuclei

6 décembre 2004

Finite systems such as atomic nuclei present at phase transition specific features different from those observed at the thermodynamic limit. Several characteristic signals were found in samples of events resulting from heavy ion collisions at and above the Fermi energy. The concomitant (...)

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Model-independent tracking of criticality signals in nuclear multifragmentation data

6 septembre 2004

We look for signals of criticality in multifragment production in heavy-ion collisions using model-independent universal fluctuations theory. The phenomenon is studied as a function of system size, bombarding energy, and impact parameter in a wide range of INDRA data. For very central (...)

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