| 1. |
- Audouin, L., et al.
(författare)
-
High-precision measurement of isotopic fission yields of 236 U
- 2018
-
Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2101-6275 .- 2100-014X. ; 193
-
Konferensbidrag (refereegranskat)abstract
- We report on the second SOFIA experiment, dedicated to the fission yields of 236U∗, analog to 235U(n,f). The measurement is based on the inverse kinematics method, using a relativistic, secondary beam of 236U. Both fission fragments are identified in mass and charge in the SOFIA recoil spectrometer. The obtained isotopic yields are compared with existing spectroscopy measurements and the elemental yields are used to discuss the treatment of the even-odd effect with energy in nuclear data libraries.
|
|
| 2. |
- Benlliure, J., et al.
(författare)
-
New experimental approaches to investigate the fission dynamics
- 2016
-
Ingår i: AIP Conference Proceedings. - : Author(s). - 1551-7616 .- 0094-243X. - 9780735414112 ; 1753
-
Konferensbidrag (refereegranskat)abstract
- The first ever achieved full identification of both fission fragments, in atomic and mass number, made it possible to define new observables sensitive to the fission dynamics along the fission path up to the scission point. Moreover, proton-induced fission of 208Pb at high energies offers optimal conditions for the investigation of dissipative, and transient effects, because of the high-excitation energy of the fissioning nuclei, its low angular momentum, and limited shape distortion by the reaction. In this work we show that the charge distribution of the final fission fragments can constrain the ground-to-saddle dynamics while the mass distribution is sensitive to the dynamics until the scission point.
|
|
| 3. |
- Chatillon, A., et al.
(författare)
-
Accurate measurements of fission-fragment yields in U-234,U-235,U-236,U-238(gamma,f) with the SOFIA set-up
- 2016
-
Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2101-6275 .- 2100-014X. - 9782759819706 ; 111
-
Konferensbidrag (refereegranskat)abstract
- SOFIA (Studies On Fission with Aladin) is a new experimental set-up dedicated to accurate measurement of fission-fragments isotopic yields. It is located at GSI, the only place to use inverse kinematics at relativistic energies in order to study the (gamma,f) electromagnetic-induced fission. The SOFIA set-up is a large-acceptance magnetic spectrometer, which allows to fully identify both fission fragments in coincidence on the whole fission-fragment range. This paper will report on fission yields obtained in U-234,U-235,U-236,U-238(gamma,f) reactions.
|
|
| 4. |
- Farget, F., et al.
(författare)
-
Transfer-induced fission in inverse kinematics: Impact on experimental and evaluated nuclear data bases
- 2015
-
Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-601X .- 1434-6001. ; 51:12, s. 1-9
-
Tidskriftsartikel (refereegranskat)abstract
- Inverse kinematics is a new tool to study nuclear fission. Its main advantage is the possibility to measure with an unmatched resolution the atomic number of fission fragments, leading to new observables in the properties of fission-fragment distributions. In addition to the resolution improvement, the study of fission based on nuclear collisions in inverse kinematics beneficiates from a larger view with respect to the neutron-induced fission, as in a single experiment the number of fissioning systems and the excitation energy range are widden. With the use of spectrometers, mass and kinetic-energy distributions may now be investigated as a function of the proton and neutron number sharing. The production of fissioning nuclei in transfer reactions allows studying the isotopic yields of fission fragments as a function of the excitation energy. The higher excitation energy resulting in the fusion reaction leading to the compound nucleus Cf-250 at an excitation energy of 45MeV is also presented. With the use of inverse kinematics, the charge polarisation of fragments at scission is now revealed with high precision, and it is shown that it cannot be neglected, even at higher excitation energies. In addition, the kinematical properties of the fragments inform on the deformation configuration at scission.
|
|
| 5. |
- Grente, L., et al.
(författare)
-
The SOFIA experiment: Measurement of 236U fission fragment yields in inverse kinematics
- 2016
-
Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2101-6275 .- 2100-014X. ; 122:01006
-
Konferensbidrag (refereegranskat)abstract
- The SOFIA (Studies On FIssion with Aladin) experiment aims at measuring fission-fragments isotopic yields with high accuracy using inverse kinematics at relativistic energies. This experimental technique allows to fully identify the fission fragments in nuclear charge and mass number, thus providing very accurate isotopic yields for low energy fission of a large variety of fissioning systems. This report focuses on the latest results obtained with this set-up concerning electromagnetic-induced fission of 236U.
|
|
| 6. |
- Martin, J. F., et al.
(författare)
-
Studies on fission with ALADIN Precise and simultaneous measurement of fission yields, total kinetic energy and total prompt neutron multiplicity at GSI
- 2015
-
Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-601X .- 1434-6001. ; 51:12, s. 1-8
-
Tidskriftsartikel (refereegranskat)abstract
- A novel technique for fission studies, based on the inverse kinematics approach, is presented. Following pioneering work in the nineties, the SOFIA Collaboration has designed and built an experimental set-up dedicated to the simultaneous measurement of isotopic yields, total kinetic energies and total prompt neutron multiplicities, by fully identifying both fission fragments in coincidence, for the very first time. This experiment, performed at GSI, permits to study the fission of a wide variety of fissioning systems, ranging from mercury to neptunium, possibly far from the valley of stability. A first experiment, performed in 2012, has provided a large array of unprecedented data regarding the nuclear fission process. An excerpt of the results is presented. With this solid starter, further improvements of the experimental set-up are considered, which are consistent with the expected developments at the GSI facility, in order to measure more fission observables in coincidence. The completeness reached in the SOFIA data, permits to scrutinize the correlations between the interesting features of fission, offering a very detailed insight in this still unraveled mechanism.
|
|
| 7. |
- Ramos, D., et al.
(författare)
-
Dependence of Fission-Fragment Properties On Excitation Energy For Neutron-Rich Actinides
- 2016
-
Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2101-6275 .- 2100-014X. - 9782759819706 ; 111
-
Konferensbidrag (refereegranskat)abstract
- Experimental access to full isotopic fragment distributions is very important to determine the features of the fission process. However, the isotopic identification of fission fragments has been, in the past, partial and scarce. A solution based on the use of inverse kinematics to study transfer-induced fission of exotic actinides was carried out at GANIL, resulting in the first experiment accessing the full identification of a collection of fissioning systems and their corresponding fission fragment distribution. In these experiments, a U-238 beam at 6.14 AMeV impinged on a carbon target to produce fissioning systems from U to Am by transfer reactions, and Cf by fusion reactions. Isotopic fission yields of Cf-250, Cm-244, Pu-240, Np-239 and U-238 are presented in this work. With this information, the average number of neutrons as a function of the atomic number of the fragments is calculated, which reflects the impact of nuclear structure around Z=50, N=80 on the production of fission fragments. The characteristics of the Super Long, Standard I, Standard II, and Standard III fission channels were extracted from fits of the fragment yields for different ranges of excitation energy. The position and contribution of the fission channels as function of excitation energy are presented.
|
|
| 8. |
- Ramos, D., et al.
(författare)
-
Experimental evidence of the effect of nuclear shells on fission dissipation and time
- 2023
-
Ingår i: Physical Review C. - 2469-9985 .- 2469-9993. ; 107:2
-
Tidskriftsartikel (refereegranskat)abstract
- Nuclear fission is still one of the most complex physical processes we can observe in nature due to the interplay of macroscopic and microscopic nuclear properties that decide the result. An example of this coupling is the presence of nuclear dissipation as an important ingredient that contributes to drive the dynamics and has a clear impact on the time of the process. However, different theoretical interpretations, and scarce experimental data make it poorly understood. In this Letter, we present the first experimental determination of the dissipation energy in fission as a function of the fragment split, for three different fissioning systems. The amount of dissipation was obtained through the measurement of the relative production of fragments with even and odd atomic numbers with respect to different initial fission energies. The results reveal a clear effect of particular nuclear shells on the dissipation and fission dynamics. In addition, the relative production of fragments with even and odd atomic numbers appears as a potential contributor to the long-standing problem of the time scale in fission.
|
|
| 9. |
- Ramos, D., et al.
(författare)
-
Fission Yields of Minor Actinides at Low Energy Through Multi-nucleon Transfer Reactions of 238U on 12C
- 2015
-
Ingår i: Acta Physica Polonica, Series B.. - 1509-5770 .- 0587-4254. ; 46:3, s. 443-446
-
Tidskriftsartikel (refereegranskat)abstract
- First preliminary results of fragments distribution as a function of the excitation energy for different fissioning systems from U to Cm and Cf-250 are presented. A new method based on inverse kinematics to study transfer-induced fission of minor actinides was carried out in GANIL in 2008, and again in 2011. In these experiments, a U-238 beam at 6.1 A MeV impinged on a carbon target to produce fissioning systems by multi-nucleon transfer reactions, resulting in the first experiments accessing the full identification of a collection of fissioning systems and their corresponding fission fragments distribution. The excitation energy is deduced from the detection of the recoil nucleus in an angular DE-E stripped silicon telescope, and the identification of the fragments is made possible by the VAMOS spectrometer.
|
|
| 10. |
- Ramos, D., et al.
(författare)
-
Insight into excitation energy and structure effects in fission from isotopic information in fission yields
- 2019
-
Ingår i: Physical Review C. - 2469-9985 .- 2469-9993. ; 99:2
-
Tidskriftsartikel (refereegranskat)abstract
- The use of the inverse kinematics technique and a magnetic spectrometer permits the simultaneous measurement of proton and neutron content of full fission fragment distributions. This paper reports new measurements of five fissioning systems - U238,Np239,Pu240,Cm244, and Cf250 - produced in inelastic scattering, transfer, and fusion reactions at different excitation energies. As a result, isotopic, elemental, and isotonic fission yields are presented. The contribution of the different fission modes and the proton even-odd effect are studied. Structure effects are investigated by means of the neutron excess and the total neutron multiplicity as a function of the fragment atomic number.
|
|
