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Surrogate neutron-capture studies with fission detection in inverse kinematics at the ESR storage ring

Bogusław Włoch, Camille Berthelot, Guy Leckenby, Beatriz Jurado, Jerome Pibernat, Manfred Grieser, Jan Glorius, Yuri Litvinov, Laurent Audouin, Bertram Blank, Klaus Blaum, Lucas Bégué--Guillou, Alex Cobo Zarzuelo, Sophia Florence Dellmann, Marc Dupuis, Oliver Forstner, Alexis Francheteau, David Freire Fernández, Miki Fukutome, Mathias Gerbaux, Jérôme Giovinazzo, Alexandre Gumberidze, Andreas Heinz, Ana Henriques, Regina Hess, Indu Jangid, Anton Kalinin, Wolfram Korten, Sergey Litvinov, Bernd Lorentz, Antonio Moro, Nikolaos Petridis, Ulrich Popp, Gregory Potel, Diego Ramos, Mathieu Roche, Mohammad Shahab Sanjari, Michele Sguazzin, Ragandeep Singh Sidhu, Uwe Spillmann, Markus Steck, Thomas Stoehlker, Takayuki Yamaguchi

Abstract

The NECTAR (Nuclear rEaCTions At storage Rings) experiment at the ESR heavy-ion storage ring at GSI Darmstadt is dedicated to surrogate reaction studies of neutron-induced reactions on heavy nuclei in inverse kinematics. In this work, we report on the implementation and performance of a newly developed fission-fragment detection system integrated into the NECTAR experimental setup. The upgraded detector configuration enables, for the first time in a surrogate experiment, the simultaneous detection of \(γ\)-decay residues, multi-neutron-emission residues, and fission fragments. The full setup was used for the first time in an experiment where a stored beam of bare \(^{238}\)U\(^{92+}\) ions at 17.24~MeV/u interacted with a gaseous deuterium target, populating excited \(^{238}\)U and \(^{239}\)U nuclei via the \(^{238}\)U(d,d') and \(^{238}\)U(d,p) reactions. We describe the fission detector geometry, design constraints, and simulation-based efficiency determination. The target-like particle identification and beam-like residue spectra demonstrating the performance of the complete setup are also shown.

Surrogate neutron-capture studies with fission detection in inverse kinematics at the ESR storage ring

Abstract

The NECTAR (Nuclear rEaCTions At storage Rings) experiment at the ESR heavy-ion storage ring at GSI Darmstadt is dedicated to surrogate reaction studies of neutron-induced reactions on heavy nuclei in inverse kinematics. In this work, we report on the implementation and performance of a newly developed fission-fragment detection system integrated into the NECTAR experimental setup. The upgraded detector configuration enables, for the first time in a surrogate experiment, the simultaneous detection of -decay residues, multi-neutron-emission residues, and fission fragments. The full setup was used for the first time in an experiment where a stored beam of bare U ions at 17.24~MeV/u interacted with a gaseous deuterium target, populating excited U and U nuclei via the U(d,d') and U(d,p) reactions. We describe the fission detector geometry, design constraints, and simulation-based efficiency determination. The target-like particle identification and beam-like residue spectra demonstrating the performance of the complete setup are also shown.
Paper Structure (7 sections, 1 equation, 5 figures)

This paper contains 7 sections, 1 equation, 5 figures.

Table of Contents

  1. Introduction
  2. Experimental setup
  3. Target-like particle telescope
  4. Fission-fragment detection system
  5. Beam-like residue detector
  6. Beam-like residue identification spectra
  7. Conclusions

Figures (5)

  • Figure 1: Schematic overview of the ESR storage ring and the NECTAR experimental setup. The red, pink, blue and green arrows represent the trajectories of the target-like residues, fission fragments and heavy residues formed after $\gamma$ and neutron emission, respectively.
  • Figure 2: $\Delta E$--$E$ spectrum from the target-like particle telescope (vertical strip 13), demonstrating separation of protons and deuterons.
  • Figure 3: Cross section of the 3D model of the experimental chamber showing the integration of the fission detectors. The target-like detector (not visible) would be on the side of the viewer.
  • Figure 4: Comparison of measured (top) and simulated (bottom) fission-fragment hit distributions on the side detector. The energy of the fragments is represented as a function of their horizontal position measured with the vertical strips of the detector.
  • Figure 5: Beam-like detector identification spectra. The horizontal axis represents the horizontal position of beam-like residues after $^{238}$U(d,p) reaction. The vertical axis is the excitation energy of the compound nucleus.