arXiv subjects

M. Rousseau

Publications and source records attributed to M. Rousseau.

At least 19 recordsLinked to original sources

arXiv2022

Design and Commissioning of the first two CYRCé Extension Beamlines

CYRCé is a TR24 cyclotron installed at the Institut Pluridisciplinaire Hubert Curien (IPHC) of Strasbourg operating at energies of 16-25 MeV and at intensities up to 400 $μ$A. The accelerator is used to produce and provide radioelements for PET and for SPECT. In 2015, IPHC started to develop a platform with the aim of performing radiobiological experiments. The PRECy platform foresees to contain three-to-five experimental stations linked to beamlines expanded from the second exit port of the cyclotron. This extension allows devoting one of the beamlines for detector studies within the framework of the CMS project. The design, the development and the commissioning of the first two beamlines are discussed in this paper.

physics.acc-ph↗

arXiv2014

Zero degree measurements of 12C fragmentation at 95 MeV/nucleon on thin targets

During therapeutic treatments using ions such as carbon, nuclear interactions between the incident ions and nuclei present in organic tissues may occur, leading to the attenuation of the incident beam intensity and to the production of secondary light charged particles. As the biological dose deposited in the tumor and the surrounding healthy tissues depends on the beam composition, an accurate knowledge of the fragmentation processes is thus essential. In particular, the nuclear interaction models have to be validated using experimental double differential cross sections which are still very scarce. An experiment was realized in 2011 at GANIL to obtain these cross sections for a 95 MeV/nucleon carbon beam on different thin targets for angles raging from 4 to 43° . In order to complete these data, a new experiment was performed on September 2013 at GANIL to measure the fragmentation cross section at zero degree for a 95 MeV/nucleon carbon beam on thin targets. In this work, the experimental setup will be described, the analysis method detailed and the results presented.

nucl-ex↗

arXiv2013

High-spin structures of 124-131Te: Competition of proton and neutron pair breakings

The 124-131Te nuclei have been produced as fission fragments in two fusion reactions induced by heavy-ions (12C + 238U at 90 MeV bombarding energy and 18O + 208Pb at 85 MeV) and studied with the Euroball array. Their high-spin level schemes have been extended to higher excitation energy from the triple gamma-ray coincidence data. The gamma-gamma angular correlations have been analyzed in order to assign spin and parity values to many observed states. Moreover the half-lives of isomeric states have been measured from the delayed coincidences between the fission-fragment detector SAPhIR and Euroball, as well as from the timing information of the Ge detectors. The behaviors of the yrast structures identified in the present work are first discussed in comparison with the general features known in the mass region, particularly the breakings of neutron pairs occupying the nuh11/2 orbit identified in the neighboring Sn nuclei. The experimental level schemes are then compared to shell-model calculations performed in this work. The analysis of the wave functions shows the effects of the proton-pair breaking along the yrast lines of the heavy Te isotopes.

nucl-ex↗

arXiv2013

High-spin structures of 88Kr and 89Rb: Evolution from collective to single-particle behaviors

The high-spin states of the two neutron-rich nuclei, 88Kr and 89R have been studied from the 18O + 208Pb fusion-fission reaction. Their level schemes were built from triple gamma-ray coincidence data and gamma-gamma angular correlations were analyzed in order to assign spin and parity values to most of the observed states. The two levels schemes evolve from collective structures to single-particle excitations as a function of the excitation energy. Comparison with results of shell-model calculations gives the specific proton and neutron configurations which are involved to generate the angular momentum along the yrast lines.

nucl-ex↗

arXiv2013

Double di ffential fragmentation cross sections measurements of 95 MeV/u 12C on thin targets for hadrontherapy

During therapeutic treatment with heavy ions like carbon, the beam undergoes nuclear fragmentation and secondary light charged particles, in particular protons and alpha particles, are produced. To estimate the dose deposited into the tumors and the surrounding healthy tissues, an accurate prediction on the fluences of these secondary fragments is necessary. Nowadays, a very limited set of double di ffential carbon fragmentation cross sections are being measured in the energy range used in hadrontherapy (40 to 400 MeV/u). Therefore, new measurements are performed to determine the double di ffential cross section of carbon on di erent thin targets. This work describes the experimental results of an experiment performed on May 2011 at GANIL. The double di ffential cross sections and the angular distributions of secondary fragments produced in the 12C fragmentation at 95 MeV/u on thin targets (C, CH2, Al, Al2O3, Ti and PMMA) have been measured. The experimental setup will be precisely described, the systematic error study will be explained and all the experimental data will be presented.

nucl-ex↗

arXiv2013

High-spin structures of 136Cs

Odd-odd 136Cs nuclei have been produced in the 18O + 208Pb and 12C + 238U fusion-fission reactions and their gamma rays studied with the Euroball array. The high-spin level scheme has been built up to ~ 4.7 MeV excitation energy and spin I ~ 16 hbar from the triple gamma-ray coincidence data. The configurations of the three structures observed above ~ 2 MeV excitation energy are first discussed by analogy with the proton excitations identified in the semi-magic 137Cs nucleus, which involve the three high-j orbits lying above the Z=50 gap, pi g_{7/2}, pi d_{5/2} and pi h_{11/2}. This is confirmed by the results of shell-model calculations performed in this work.

nucl-ex↗

arXiv2013

Comparison of two analysis methods for nuclear reaction measurements of 12C +12C interactions at 95 MeV/u for hadrontherapy

During therapeutic treatment with heavier ions like carbon, the beam undergoes nuclear fragmentation and secondary light charged particles, in particular protons and alpha particles, are produced. To estimate the dose deposited into the tumors and the surrounding healthy tissues, the accuracy must be higher than ($\pm$3% and$\pm$1 mm). Therefore, measurements are performed to determine the double differential cross section for different reactions. In this paper, the analysis of data from 12C +12C reactions at 95 MeV/u are presented. The emitted particles are detected with \DeltaEthin-\DeltaEthick-E telescopes made of a stack of two silicon detectors and a CsI crystal. Two different methods are used to identify the particles. One is based on graphical cuts onto the \DeltaE-E maps, the second is based on the so-called KaliVeda method using a functional description of \DeltaE versus E. The results of the two methods will be presented in this paper as well as the comparison between both.

physics.med-ph↗

arXiv2012

High-spin structures of five N=82 isotones: 136Xe, 137Cs, 138Ba, 139La, and 140Ce

Five N=82 isotones have been produced in two fusion-fission reactions and their gamma-rays studied with the Euroball array. The high-spin states of 139La have been identified for the first time, while the high-spin yrast and near-to-yrast structures of the four others have been greatly extended. From angular correlation analysis,spin values have been assigned to some states of 136Xe and 137Cs. Several cascades involving gamma-rays of 139La have been found to be delayed, they deexcite an isomeric state with T1/2= 315(35) ns located at 1800-keV excitation energy. The excited states of these five N=82 isotones are expected to be due to various proton excitations involving the three high-j subshells located above the Z=50 shell closure. This is confirmed by the results of shell-model calculations performed in this work. In addition, high-spin states corresponding to the excitation of the neutron core have been unambiguously identified in 136Xe, 137Cs, and 138Ba.

nucl-ex↗

arXiv2012

High-spin states with seniority v=4,4,6 in 119-126Sn

The 119-126Sn nuclei have been produced as fission fragments in two reactions induced by heavy ions: 12C+238U at 90 MeV bombarding energy, 18O+208Pb at 85 MeV. Their level schemes have been built from gamma rays detected using the Euroball array. High-spin states located above the long-lived isomeric states of the even- and odd-A 120-126Sn nuclei have been identified. Moreover isomeric states lying around 4.5 MeV have been established in 120,122,124,126Sn from the delayed coincidences between the fission fragment detector SAPhIR and the Euroball array. The states located above 3-MeV excitation energy are ascribed to several broken pairs of neutrons occupying the nu h11/2 orbit. The maximum value of angular momentum available in such a high-j shell, i.e. for mid-occupation and the breaking of the three neutron pairs, has been identified. This process is observed for the first time in spherical nuclei.

nucl-ex↗

arXiv2010

Clusters in Light Nuclei

A great deal of research work has been undertaken in the alpha-clustering study since the pioneering discovery, half a century ago, of 12C+12C molecular resonances. Our knowledge of the field of the physics of nuclear molecules has increased considerably and nuclear clustering remains one of the most fruitful domains of nuclear physics, facing some of the greatest challenges and opportunities in the years ahead. In this work, the occurence of "exotic" shapes in light N=Z alpha-like nuclei is investigated. Various approaches of superdeformed and hyperdeformed bands associated with quasimolecular resonant structures are presented. Results on clustering aspects are also discussed for light neutron-rich Oxygen isotopes.

nucl-ex↗

arXiv2010

Cluster Model For Reactions Induced By Weakly Bound And/Or Exotic Halo Nuclei With Medium-Mass Targets

An experimental overview of reactions induced by the stable, but weakly-bound nuclei 6Li, 7Li and 9Be, and by the exotic, halo nuclei 6He, 8He, 8B, and 11Be on medium-mass targets, such as 58Ni, 59Co or 64Zn, is presented. Existing data on elastic scattering, total reaction cross sections, fusion processes, breakup and transfer channels are discussed in the framework of a CDCC approach taking into account the breakup degree of freedom.

nucl-ex↗

arXiv2009

Binary reaction decays from 24Mg+12C

Charged particle and gamma decays in 24Mg* are investigated for excitation energies where quasimolecular resonances appear in 12C+12C collisions. Various theoretical predictions for the occurence of superdeformed and hyperdeformed bands associated with resonance structures with low spin are discussed within the measured 24Mg* excitation energy region. The inverse kinematics reaction 24Mg+12C is studied at E_lab(24Mg) = 130 MeV, an energy which enables the population of 24Mg states decaying into 12C+12C resonant break-up states. Exclusive data were collected with the Binary Reaction Spectrometer in coincidence with EUROBALL IV installed at the VIVITRON Tandem facility at Strasbourg. Specific structures with large deformation were selectively populated in binary reactions and their associated gamma decays studied. Coincident events associated with inelastic and alpha-transfer channels have been selected by choosing the excitation energy or the entry point via the two-body Q-values. The analysis of the binary reaction channels is presented with a particular emphasis on 24Mg-gamma, 20Ne-gamma and 16O-gamma coincidences. New information (spin and branching ratios) is deduced on high-energy states in 24Mg and 16O, respectively.

nucl-ex↗

arXiv2008

Reaction mechanisms in 24Mg+12C and 32S+24Mg

The occurence of "exotic" shapes in light N=Z alpha-like nuclei is investigated for 24Mg+12C and 32S+24Mg. Various approaches of superdeformed and hyperdeformed bands associated with quasimolecular resonant structures with low spin are presented. For both reactions, exclusive data were collected with the Binary Reaction Spectrometer in coincidence with EUROBALL IV installed at the VIVITRON Tandem facility of Strasbourg. Specific structures with large deformation were selectively populated in binary reactions and their associated $γ$-decays studied. The analysis of the binary and ternary reaction channels is discussed.

nucl-ex↗

arXiv2006

Strong Deformation Effects in Hot Rotating 46Ti

Exotic-deformation effects in 46Ti nucleus were investigated by analysing the high-energy gamma-ray and the alpha-particle energy spectra. One of the experiments was performed using the charged-particle multi-detector array ICARE together with a large volume (4"x4") BGO detector. The study focused on simultaneous measurement of light charged particles and gamma-rays in coincidence with the evaporation residues. The experimental data show a signature of very large deformations of the compound nucleus in the Jacobi transition region at the highest spins. These results are compared to data from previous experiments performed with the HECTOR array coupled to the EUROBALL array, where it was found that the GDR strength function is highly fragmented, strongly indicating a presence of nuclei with very large deformation.

nucl-ex↗

arXiv2006

Deformation Effects in Hot Rotating 46Ti Probed by the Charged Particle Emission and GDR gamma-Decay

The 46Ti* compound nucleus, as populated by the fusion-evaporation reaction 27Al+19F at the bombarding energy of E_lab=144 MeV, has been investigated by charged particle spectroscopy using the multidetector array ICARE at the VIVITRON tandem facility of the IReS (Strasbourg). The light charged particles and high-energy gamma-rays from the GDR decay have been measured in coincidence with selected evaporation residues. The CACARIZO code, a Monte Carlo implementation of the statistical-model code CASCADE, has been used to calculate the spectral shapes of evaporated alpha-particles which are compared with the experimental coincident spectra. This comparison indicates the signature of large deformations (possibly superdeformed and hyperdeformed shapes) present in the compound nucleus decay. The occurrence of the Jacobi shape transition is also discussed in the framework of a newly developed rotating liquid drop model.

nucl-ex↗

arXiv2004

Study of Deformation Effects in the Charged Particle Emission from 46Ti

The 46Ti compound nucleus, as populated by the fusion-evaporation reaction 27Al + 19F at the bombarding energy of 144 MeV, has been investigated by charged particle spectroscopy using the multidetector array ICARE at the VIVITRON tandem facility of the IReS (Strasbourg). The light charged particles have been measured in coincidence with evaporation residues. The CACARIZO code, a Monte Carlo implementation of the statistical-model code CASCADE, has been used to calculate the spectral shapes of evaporated alpha-particles which are compared with the experimental spectra. This comparison indicates the possible signature of large deformations of the compound nucleus.

nucl-ex↗

arXiv2004

How does breakup influence near-barrier fusion of weakly bound light nuclei ?

The influence on the fusion process of coupling to collective degrees of freedom has been explored. The significant enhancement of he fusion cross setion at sub-barrier energies was understood in terms of the dynamical processes arising from strong couplings to collective inelastic excitations of the target and projectile. However, in the case of reactions where breakup becomes an important process, conflicing model predictions and experimental results have been reported in the literature. Excitation functions for sub- and near-barrier total (complete + incomplete) fusion cross sections have been measured for the $^{6,7}$Li + $^{59}$Co at the Vivitron facility and at the 8UD Pelletron tandem facility using standard $γ$-ray techniques. The data extend to medium-mass systems previous works exploring the coupling effects in fusion reactions of both lighter and heavier systems. Results of continuum-discretized coupled channel (CDCC) calculations indicate a small enhancement of total fusion for the more weakly bound $^{6}$Li at sub-barrier energies, with similar cross sections for both reactions at and above the barrier. A systematic study of $^{4,6}$He induced fusion reactions with the CDCC method is in progress. The understanding of the reaction dynamics involving couplings to the breakup channels requires th explicit measurement of precise elastic scattering data as well as yields leading to the breakup itself. Recent coincidence experiments for $^{6,7}$Li + $^{59}$Co are addressing this issue. The particle identification of the breakup products have been achieved by measuring the three-body final-state correlations.

nucl-ex↗

arXiv2003

Search for 12C+12C molecule in 24Mg* populated by 24Mg+12C

The gamma-decay properties of 24Mg excited states are investigated in the inverse reaction 24Mg+12C at E(24Mg) = 130 MeV. At this energy the direct inelastic scattering populates a 24Mg* energy region where 12C+12C breakup resonances can occur. Very exclusive data were collected with the Binary Reaction Spectrometer (BRS) in coincidence with EUROBALL installed at the VIVITRON Tandem facility of the IReS at Strasbourg. The experimental detection system is decribed and preliminary results of binary reaction coincid data are presented.

nucl-ex↗