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Project List » Photofission studies with the ELIGANT-TN instrument - Technique Developement

Photofission studies with the ELIGANT-TN instrument - Technique Developement
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Acronym: GANT-PhotoFiss
Contracting Authority: Institutul de Fizica Atomica (IFA)
Number / Date of the contract: ELI-RO 14 / 2020-10-16
PN-III-P5/Subprogramul 5.1
Project Manager: Dr. Dan Mihai Filipescu
Partners: University of Bucharest
Starting date / finishing date: 2020-10-16 / 2023-10-15
Project value: 750000 RON
Abstract: The mission of the GANT-PhotoFiss project has been to develop a new technique for simultaneous photofission and photoneutron cross section measurements with the ELI-NP Gamma Above Neutron Threshold Thermal Neutrons (ELIGANT-TN) detection setup, along with the associated LCS gamma-ray beam diagnostics procedures.
The project has been led by Dr. Dan Mihai Filipescu at the Nuclear Physics Department of the Horia Hulubei National Institute for R&D in Physics and Nuclear Engineering, in partnership with Prof. Dr. Anabella Tudora at the Nuclear Physics Department of the Faculty of Physics, University of Bucharest. The GANT-PhotoFiss project was allocated 750.000 RON funding to provide staff positions for three years as well as the necessary equipment, logistics and travels.
Up to 2020, only Fission Fragment detection experiments had been planned in the photofission programme at ELI-NP, providing information on photofission cross-sections and mass, charge, angular, and kinetic energy distributions. Although the foreseen scientific output is highly interesting for describing the process of nuclear fission, the current ELI-NP photofission programme includes no investigation on the Prompt Fission Neutron (PFN) emission - critical nuclear data required by nuclear applications.
Project GANT-PhotoFiss has developed a method for measuring photofission cross sections and PFNs multiplicity distributions and PFNs average energy spectra by using the Flat Efficiency Detector ELIGANT-TN. The ELIGANT-TN instrument was initially developed by the ELIGANT group for photoneutron measurements and it is currently fully functional and commissioned. We have produced a ready to use algorithm for combined photofission and photoneutron Day 1 experiments at the ELI-NP Gamma Beam System.
The algorithm has been applied for validation on 238U and 232Th photofission data sets measured in the Giant Dipole Resonance region at the NewSUBARU Laser Compton Scattering gamma-ray beam facility. Within the GANT-PhotoFiss project, we have obtained precise 238U and 232Th experimental values for:
- the total photoabsorption cross section (g,abs);
- the photoneutron (g,n), (g,2n), (g,3n) and photofission (g,F) cross sections;
- the parameters of the prompt fission neutron multiplicity distribution: mean number of prompt neutrons per fission act, and the width of the neutron multiplicity distribution;
- the average energy of the prompt fission neutrons and for the photoneutrons emitted in the (g,n), (g,2n) si (g,3n) reactions;
- the cross sections for the first (g,f) and second (g,nf) photofission chances, along with their contributions to the total number of prompt neutrons per fission act.
The experimental results have been reproduced by statistical model calculations with the EMPIRE code and with prompt fission emission calculations in the frame of the Los Alamos model.
A main outcome of the project has been the training of local man-power with know-how on the associated neutron multiplicity sorting technique, Laser Compton Scattering gamma-ray beam diagnostics and necessary theoretical modelling (one PhD studen). Within the GANT-PhotoFiss project, we have developed a mode for simulating LCS gamma-ray beam sources, model which has been integrated in the eliLaBr simulation code available on the GitHub repository: https://github.com/dan-mihai-filipescu/eliLaBr

Objectives:

Train man power and gain local know-how for future photofission experiments at ELI-NP

Develop a neutron multiplicity sorting method for distinctly extracting the photofission (γ, f) and photoneutron (γ, xn) cross sections

Improve gamma beam diagnostics methods and develop a new energy unfolding technique for determining the energy spectrum of the incident LCS γ-ray beam.

Apply the methods on NewSUBARU photofission data for ²³⁸U and ²³²Th. Produce the experimental cross sections for the photofission and photoneutron cross sections in the 6 to 20 MeV excitation energy. Solve discrepancies between existing data sets of Livermore and Saclay.

Produce a new and reliable statistical model evaluation for the photon induced reactions on ²³⁸U and ²³²Th.

THE STAGES OF THE PROJECT AND DELIVERY DATES
1. Preliminary stage of 238U and 232Th photofission data analysis and modeling of prompt neutron emission (2020-12-31) Results
2. Preliminary stage of 238U and 232Th photofission data analysis and modeling of prompt neutron emission (2021-12-31) Results
3. Photofission data analysis-method development and validation on 238U and 232Th data (2022-12-31) Results
4. Statistical model evaluations of photon induced reactions on 238U and 232Th (2023-10-15) Results
RESULTS [Project Activity Report]
PUBLISHED ARTICLES
RESEARCH TEAM

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