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PARTICIPANTS
H. Álvarez-Pol (1), L. Audouin (2), Y. Ayyad (1), G. Bélier (3), J. Benlliure (1), G. Boutoux (3),
E. Casarejos (4), A. Chatillon (3), D. Cortina-Gil (1), T. Gorbinet (3), A. Heinz (5), A. Kelic-Heil (6)
B. Laurent (3), J.-F. Martin (3), C. Paradela (1), E. Pellereau (3), B. Pietras (1), D. Ramos (1),
J.L. Rodríguez-Sánchez (1), C. Rodríguez-Tajes (7), D. Rossi (6), H. Simon (6),
J. Vargas (1), and B. Voss (6)
(1) Universidade de Santiago de Compostela, E-15782 Santiago de Compostela, Spain
(2) Institut de Physique Nucléaire d’Orsay, F-91406 Orsay, France
(3) CEA / DAM, F-91297 Arpajon, France
(4) Universidad de Vigo, E-36200 Vigo, Spain
(5) Chalmers University of Technology, SE-412 96 Gothenburg, Sweden
(6) GSI-Helmholtzzentrum für Schwerionenforschung GmbH, D-64291 Darmstadt, Germany
(7) Grand Accélérateur National d’Ions Lourds, F-14076 Caen Cedex 05, France
Date: 27-29 September 2012
PhD student: J.L. Rodríguez Sánchez. https://orcid.org/0000-0002-4702-5294
TECHNICAL INFO
SOFIA and ANDES experiments
The SOFIA (Studies On Fission with Aladin) and ANDES experiments are the first step of the forthcoming generation of fission experiments developed at GSI, which investigate structural and dynamic effects in fission measuring for the first time the charge and the mass of both fission fragments thanks to a magnetic separation and the use of the inverse kinematics technique. For this, a complex experimental setup (see figure) was mounted at the ALADIN-LAND cave at GSI which is constituted by ionization chambers, MWPCs and ToF-Walls . Moreover, we also measured the neutron multiplicities and the light-charged particles (LCP) emitted in coincidence with fission, being the neutrons and the light-charged particles measured by the neutron detector LAND and a segmented plastic-scintillator wall, respectively.
Figure: ANDES setup used to investigate the reaction 208Pb+p in inverse kinematics.
Experimental setup
The experimental setup is divided in two parts, one used to characterize the incoming beam ions and another dedicated to measure the fission fragments. The first part consists of a plastic scintillator detector (start) used to measure the time-of-flight (ToF) of the fragments, a multi-sampling ionization chamber (MUSIC) and a time projection chamber (TPC). These last two detectors provide the beam identification and its position on the target, respectively.
The second part consists of a double multi-sampling ionization chamber (Twin MUSIC), two multiwire proportional counters (MWPCs), a large acceptance dipole magnet (ALADIN) and a ToF Wall. The Twin MUSIC chamber, filled with P25 (74.5% of Argon, 25% of CH4, and 0.5% of CO2) gas, has a central vertical cathode that divides its volume (60 cm long, 20 cm high and 20 cm wide) into two active parts, segmented in ten anodes each. These anodes provide ten independent energy-loss and drift-time measurements, which allow to obtain the atomic numbers with a resolution below 0.43 charge units full width at half maximum (FWHM) and the angles on the plane X-Z with a resolution below 0.6 mrad (FWHM). MWPCs, situated in front and behind the dipole magnet, provide the horizontal (X) and vertical (Y) positions of the fission fragments. The MWPC situated in front of the dipole magnet (20 cm high and 20 cm wide) provides the X and Y positions with a resolution around 200 μm and 1.5 mm (FWHM), respectively, while the MWPC situated behind the dipole magnet (60 cm high and 90 cm wide) provides those positions with a resolution around 300 μm and 2 mm (FWHM), respectively. Both MWPCs were filled with a mixture of Argon (80%) and CO2 (20%). Finally, a ToF Wall (60 cm high and 90 cm wide) made of 28 plastic scintillators (3.2 cm wide, 60 cm long and 0.5 cm thick) allows to measure the ToF of the fission fragments with respect to the start signal provided by the plastic scintillator located at the entrance of the experimental setup with a resolution around 40 ps (FWHM). The ALADIN magnet was set to a magnetic field of 1.6 T and its gap (200 cm long, 50 cm high and 100 cm wide) was filled with helium gas at atmospheric pressure.
In addition, two pipes, also filled with helium gas at atmospheric pressure, were mounted in front of the Twin MUSIC chamber and behind the dipole magnet ALADIN. The pipes were sealed by windows made of aluminized-mylar foils with a thickness of 35 μm and 50 μm, respectively. In all the cases, the helium gas was employed to reduce the energy and angular straggling of the fission fragments.
Finally, light-charged particles emitted in coincidence with fission fragments were identified by using a ToF wall detector (ToF of LCPs), placed in front the Twin MUSIC chamber. This detector consists of two detection planes of segmented plastic-scintillators (50 cm long, 6 cm wide and 1 cm thick), one with six horizontal paddles and another with six vertical paddles, which leave a square hole (12.5 × 12.5 cm2) in the center for the transmission of the fission fragments.
Figure : Top schematic view of the experimental setup. Sizes are not to scale.
MUSIC
M. Pfüzner et al., Nucl. Instrum. Methods Phys. Res., Sect. B 86, 213 (1994).
MUSIC manual (PDF file)
TPC
R. Janik et al., Nucl. Instrum. Methods Phys. Res., Sect. A 640, 54-57 (2011).
The liquid hydrogen target (LH2)
P. Chesny et al., Safety report SPALADIN target. IRFU (2007).
Twin MUSIC
MWPCs
C. Finck et al., J. Phys.: Conf. Ser. 50, 397 (2006).
ToF Wall
A. Ebran et al., Nucl. Instrum. Methods Phys. Res., Sect. A 728, 40 (2013).
Large Area Neutron Detector (LAND)
Data acquisition
Location of lmd files:
At Santiago:
- One external hard drive of 1 TB (currently at J.Luis' desk)
- Cluster in /data4/joseluis/andes_lmds
At GSI:
- /d/land1/andes
Simulation
MAIN RESULTS
Dissipative effects in fission investigated in complete kinematics measurements
J.L. Rodríguez-Sánchez, J. Benlliure, H. Alvarez-Pol, D. Cortina-Gil et al., 2017)
Fission dynamics at high excitation energies investigated in complete kinematics measurements
J.L. Rodríguez-Sánchez, J. Benlliure, H. Alvarez-Pol, D. Cortina-Gil et al., 2017)
Accurate isotopic fission yields of electromagnetically induced fission of 238U measured in inverse kinematics at relativistic energies
E. Pellereau et al., Phys. Rev. C 95, 054603 (2017)
Spallation-induced fission reactions
J. Benlliure and J.L. Rodríguez-Sánchez, Eur. Phys. J. Plus 132, 120 (2017)
Presaddle and postsaddle dissipative effects in fission using complete kinematics measurements
J.L. Rodríguez-Sánchez, J. Benlliure, H. Alvarez-Pol, D. Cortina-Gil et al., Phys. Rev. C 94, 061601(R) (2016)
Light charged particles emitted in fission reactions induced by protons on 208Pb
J.L. Rodríguez-Sánchez, J. Benlliure, C. Paradela, H. Alvarez-Pol, Y. Ayyad, E. Casarejos, D. Cortina-Gil, B. Pietras, D. Ramos, J. Vargas et al., Phys. Rev. C 94, 034605 (2016)
New experimental approaches to investigate the fission dynamics
J. Benlliure, J.L. Rodríguez-Sánchez, H. Alvarez-Pol, Y. Ayyad, E. Casarejos, D. Cortina-Gil, C. Paradela, B. Pietras, D. Ramos, J. Vargas et al., AIP Conf. Proc. 1753, 030014 (2016)
Dissipative effects in fission investigated with proton-on-lead reactions
J.L. Rodríguez-Sánchez, J. Benlliure, H. Alvarez-Pol, Y. Ayyad, E. Casarejos, D. Cortina-Gil, C. Paradela, B. Pietras, D. Ramos, J. Vargas et al., EPJ Web of Conferences 117, 08017 (2016)
Studies on fission with ALADIN
J.-F. Martin et al., Eur. Phys. J. A 51, 174 (2015)
Constraining the level density using fission of lead projectiles
J.L. Rodríguez-Sánchez, H. Alvarez-Pol, Y. Ayyad, J. Benlliure, E. Casarejos, D. Cortina-Gil, C. Paradela, B. Pietras, D. Ramos, J. Vargas et al., Phys. Rev. C 92, 044612 (2015)
Complete characterization of the fission fragments produced in reactions induced by 208Pb projectiles on proton at 500A MeV
J.L. Rodríguez-Sánchez, H. Alvarez-Pol, Y. Ayyad, J. Benlliure, E. Casarejos, D. Cortina-Gil, C. Paradela, B. Pietras, D. Ramos, J. Vargas et al., Phys. Rev. C 91, 064616 (2015)
A sample of the results of the first SOFIA experiment
T. Gorbinet, Y. Ayyad, J. Benlliure, M. Caamaño, E. Casarejos, D. Cortina-Gil, B. Fernández-Domínguez, C. Paradela, J.L. Rodríguez-Sánchez, J. Vargas et al., Phys. Procedia 64, 101 (2015)
Transient effects in fission investigated with proton-on-lead reactions in complete kinematic measurements
J.L. Rodríguez-Sánchez, H. Alvarez-Pol, Y. Ayyad, J. Benlliure, E. Casarejos, D. Cortina-Gil, C. Paradela, B. Pietras, D. Ramos, J. Vargas et al., Phys. Procedia 64, 157 (2015)
Proton-induced fission cross sections on 208Pb at high kinetic energies
J.L. Rodríguez-Sánchez, H. Alvarez-Pol, Y. Ayyad, J. Benlliure, E. Casarejos, D. Cortina-Gil, C. Paradela, B. Pietras, D. Ramos, J. Vargas et al., Phys. Rev. C 90, 064606 (2014)
SOFIA, a Next-Generation Facility for Fission Yields Measurements and Fission Study. First Results and Perspectives
L. Audouin et al., Nuclear Physics and Gamma-Ray Sources for Nuclear Security and Nonproliferation, Chapter 26. December 2014. ISBN: 978-981-4635-44-8.
THEORY-3: Scientific Workshop on Nuclear Fission dynamics and the Emission of Prompt Neutrons and Gamma Rays
16-18 September 2014, Opatija, Croatia
Identification and Reconstruction of Fission Fragments for Proton-Induced
Fission of 208Pb at 500 MeV in Inverse Kinematics
J.L. Rodriguez-Sánchez et al., GSI Scientific Report 2013
Total Fission Cross Sections for Proton-Induced Fission of 208Pb
J.L. Rodriguez-Sánchez et al., GSI Scientific Report 2013
SOFIARoot: Simulation of the SOFIA/ANDES Setup
J.L. Rodriguez-Sánchez et al., GSI Scientific Report 2013
Fission of highly excited nuclei investigated in complete kinematic measurements
J.L. Rodriguez-Sánchez et al., EPJ Web of Conferences 62, 07009 (2013)
SOFIA: An innovative setup to measure complete isotopic yield of fission fragments
E. Pellereau et al., EPJ Web of Conferences 62, 06005 (2013)
Fission2013
Château de Caen, France, 05/2013
The SOFIA experiment
G. Boutoux et al., Physics Procedia 47, 166-171 (2013)
Fission Dynamics at High Excitation Energy in Complete Kinematics Measurements of the Reaction 208Pb at 500A MeV
J.L. Rodriguez-Sánchez et al., GSI Scientific Report 2012
Euroschool on exotic beams 2012
Athens, Greece, 09/2012
Master thesis: Simulation of the SOFIA experiment at GSI for studies of fission in inverse kinematics, 07/2012