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The 1st Nuclear Spectroscopy Laboratory Seminar
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Lecturer:
Ms. Julie-Fiona Martin (CEA)
Title:SOFIA : Fisson studies at GSI
Date & Time:March 25th (Tuesday), 13:30-15:00
Place: RIBF Hall, RIBF building, RIKEN Wako Campus
Language:English
Abstract:
The experiment is led at the heavy-ion accelerator GSI in Darmstadt, Germany. This facility provides relativistic radioactive secondary beams, which are sorted and identied through the FR-S (FRagment Separator) and sent to Cave-C for the fission experiment itself. At the entrance of the experimental area, the seconday beam is excited by Coulomb interaction when flying through an inert target; the de-excitation process involves low-energy fission. The most has been made of the high-acceptance dipole ALADIN, and a high-resolution recoil spectrometer has been implemented around this magnet by the SOFIA collaboration to reach for unprecedented measurement resolutions. The combination of the measurements of each fragment's energy loss, time-of-flight [1] and deviation in the magnet enables an unambiguous identication of both fragments.
During the rst SOFIA experiment, in August 2012 [2], a twofold goal waspursued:
- Actinides for the applications: three days were dedicated to actinidesof interest for the applications (U; Np). High statistics were recorded,and complete isotopic yields as well as precise kinetic energy measurement were extracted.
- Lighter neutron-decient nuclei, to hunt for fission modes transitions : the remaining time has been devoted to browsing thenuclear landscape, with about 75 fissionning systems ranging from 184Hg to 230Th. These isotopes' fission was recorded with lower statistics;yet this is sucient to observe transitions from symmetric to asymmetric fission.
First results on the fission of actinides (U, Np) would be presented. Interesting features include the even-odd effect on nuclear charges and neutron number yields, and scission conguration's signature on yields and total kinetic energy.
[1] A. Ebran et. al., NIM A 728, 40-46 (2013)
[2] G. Boutoux et. al., Phys. Proc. 47, 166-171 (2013)
