Fission yield measurements at IGISOL

S. Pomp,V. Simutkin,D. Gorelov,M. Lantz,A. Solders,V. Rakopoulos,S. Rinta-Antila,A. Al-Adili,V.S. Kolhinen,The Igisol Group ,A.V. Prokofiev,A. Jokinen,H. Penttilä,A. Mattera,I. Moore

doi:10.1051/epjconf/201612201008

S. Pomp, V. Simutkin + Show 13 more

Open Access

https://doi.org/10.1051/epjconf/201612201008

Copy DOI

Abstract

The fission product yields are an important characteristic of the fission process. In fundamental physics, knowledge of the yield distributions is needed to better understand the fission process. For nuclear energy applications good knowledge of neutroninduced fission-product yields is important for the safe and efficient operation of nuclear power plants. With the Ion Guide Isotope Separator On-Line (IGISOL) technique, products of nuclear reactions are stopped in a buffer gas and then extracted and separated by mass. Thanks to the high resolving power of the JYFLTRAP Penning trap, at University of Jyvaskyla, fission products can be isobarically separated, making it possible to measure relative independent fission yields. In some cases it is even possible to resolve isomeric states from the ground state, permitting measurements of isomeric yield ratios. So far the reactions U(p,f) and Th(p,f) have been studied using the IGISOL-JYFLTRAP facility. Recently, a neutron converter target has been developed utilizing the Be(p,xn) reaction. We here present the IGISOL-technique for fission yield measurements and some of the results from the measurements on proton induced fission. We also present the development of the neutron converter target, the characterization of the neutron field and the first tests with neutron-induced fission.

Highlights

The Ion Guide Isotope Separator On-Line (IGISOL) facility at University of Jyväskylä has for several decades been used for experiments with exotic nuclei far from the valley of β stability
IGISOL is an acronym for Ion Guide Isotope Separator On-Line and is a technique that has been developed in Jyväskylä since the early 1980’s [3]
At IGISOL-JYFLTRAP fission yield experiments have been performed with 25 MeV protons on Th [10] and 238U [11], measuring the isobaric chains for more than 20 different elements

Summary

Introduction

The IGISOL facility at University of Jyväskylä has for several decades been used for experiments with exotic nuclei far from the valley of β stability. The fissioning nuclei are so far from stability that their fission yields have to be calculated based on theoretical models To improve these models, accurate experimental data on the fission of reachable nuclei, such as 238U, is needed. For nuclear energy applications good knowledge of neutron induced fission product yields is crucial in many aspects, including criticality and reactivity calculations for reactor design, dosimetry and fission gas production for reactor safety and improved burn-up predictions. Good knowledge of the composition of the spent fuel is required for the management of the nuclear waste, i.e. depositories, reprocessing, transmutation and so on. It is needed for Generation IV reactor concepts, including fast reactors where fast neutrons change the fission yield distribution compared to thermal neutrons.

Experimental method of IGISOL

Proton and deuteron induced fission yields

Isomeric yield ratios

Neutron induced fission yields

Status and outlook