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This work aims at measuring prompt-fission neutrons at different excitation energies of the nucleus. Two independent techniques, the 2E-2v and the 2E techniques, are used to map the characteristics of the mass-dependent prompt fission neutron multiplicity, 7(A), when the excitation energy is increased. The VERDI 2E-2v spectrometer is being developed at JRC-GEEL. The Fission Fragment (FF) energies are measured using two arrays of 16 silicon (Si) detectors each. The FFs velocities are obtained by time-of-flight, measured between micro-channel plates (MCP) and Si detectors. With MCPs placed on both sides of the fission source, VERDI allows for independent timing measurements for both fragments. Cf-252(sf) was measured and the present results revealed particular features of the 2E-2v technique. Dedicated simulations were also performed using the GEF code to study important aspects of the 2E-2v technique. Our simulations show that prompt neutron emission has a non-negligible impact on the deduced fragment data and affects also the shape of 17(A). Geometrical constraints lead to a total-kinetic energy-dependent detection efficiency. The 2E technique utilizes an ionization chamber together with two liquid scintillator detectors. Two measurements have been performed, one of Cf-252(sf) and another one of thermal-neutron induced fission in U-235(n,f). Results from Cf-252(sf) are reported here.

The neutrons for science (NFS) facility is a component of SPIRAL-2, the new superconducting linear accelerator built at GANIL in Caen (France). The proton and deuteron beams delivered by the accelerator will allow producing intense neutron fields in the 100 keV-40 MeV energy range. Continuous and quasi-mono-kinetic energy spectra, respectively, will be available at NFS, produced by the interaction of a deuteron beam on a thick Be converter and by the Li-7(p, n) reaction on thin converter. The pulsed neutron beam, with a flux up to two orders of magnitude higher than those of other existing time-of-flight facilities, will open new opportunities of experiments in fundamental research as well as in nuclear data measurements. In addition to the neutron beam, irradiation stations for neutron-, proton- and deuteron-induced reactions will be available for cross-sections measurements and for the irradiation of electronic devices or biological cells. NFS, whose first experiment is foreseen in 2018, will be a very powerful tool for physics, fundamental research as well as applications like the transmutation of nuclear waste, design of future fission and fusion reactors, nuclear medicine or test and development of new detectors.

Data on fission yields and isomeric yield ratios (IYR) are tools to study the fission process, in particular the generation of angular momentum. We use the IGISOL facility with the Penning trap JYFLTRAP in Jyvaskyla, Finland, for such measurements on Th-232 and U-nat targets. Previously published fission yield data from IGISOL concern the Th-232(p,f) and U-238(p,f) reactions at 25 and 50 MeV. Recently, a neutron source, using the Be(p,n) reaction, has been developed, installed and tested. We summarize the results for (p,f) focusing on the first measurement of IYR by direct ion counting. We also present first results for IYR and relative yields for Sn and Sb isotopes in the 128-133 mass range from U-nat(n,f) based on gamma-spectrometry. We find a staggering behaviour in the cumulative yields for Sn and a shift in the independent fission yields for Sb as compared to current evaluations. Plans for the future experimental program on fission yields and IYR measurements are discussed.

The investigation of the dynamics of the nuclear fission process has been a standing research topic at the JRC-Geel during the past decades. Recently the focus was put on the de-excitation of fission fragments through the emission of prompt neutrons and gamma-rays. To this end new detector systems were developed at JRC-Geel, e.g. a position sensitive ionization chamber used in conjunction with the neutron scintillator array SCINTIA. The array has been tested using the spontaneous fission of Cf-252. The goal is to study correlations of fission fragments with prompt neutron emission in the resolved resonance region. No strong fluctuations of the average prompt neutron multiplicity for the strongest resonances in U-235 were observed. From the present data the mass-dependent neutron multiplicity, v(A), was generated. The v(A) distribution shows a more pronounced dip around the doubly magic mass A = 132 and at very low masses around A similar to 80 compared to the literature. In addition, a steeper slope for v(TKE) is observed. Cross checking with fragment data clearly shows a narrower mass and total kinetic energy (TKE) distribution. The 2E-2v spectrometer VERDI (VElocity foR Direct mass Identification) became operational. For Cf-252(sf) superior mass resolution is observed compared to a twin Frisch-grid ionization chamber. For post-neutron mass distributions still some issues need to be solved and v(A), being the difference of pre- and post-neutron mass distributions, is still deviating from literature data. Eventually, VERDI will provide a complementary measurement technique to assess v(A) and v(TKE). In addition, an experimental campaign to measure v(A) as a function of incident neutron energy for different actinides has been started. First tests show promising results.

The double-energy double-velocity (2E-2v) method allows assessing fission-fragment mass yields prior to and after prompt neutron emission with high resolution. It is, therefore, considered as a complementary technique to assess average prompt neutron multiplicity as a function of fragment properties. We have studied the intrinsic features of the 2E-2v method by means of event-wise generated fission-fragment data and found short-comings in the method itself as well as in some common practices of application. We find that the 2E-2v method leads to large deviations in the correlation between the prompt neutron multiplicity and pre-neutron mass, which deforms and exaggerates the so-called “sawtooth” shape of nubar(A). We have identified the treatment of prompt neutron emission from the fragments as the origin of the problem. The intrinsic nature of this deficiency risks to render 2E-2v experiments less interesting. We suggest a method to correct 2E-2v data that can even be applied on existing measurements.

The nuclear de-excitation process of fission fragments (FF) provides fundamental information for the understanding of nuclear fission and nuclear structure in neutron-rich isotopes. The variation of the prompt-neutron multiplicity, ν(A), as a function of the incident neutron energy (En) is one of many open questions. It leads to significantly different treatments in various fission models and implies that experimental data are analyzed based on contradicting assumptions. One critical question is whether the additional excitation energy (Eexc) is manifested through an increase of ν(A) for all fragments or for the heavy ones only. A systematic investigation of ν(A) as a function of En has been initiated. Correlations between prompt-fission neutrons and fission fragments are obtained by using liquid scintillators in conjunction with a Frisch-grid ionization chamber. The proof-of-principle has been achieved on the reaction 235U(nth,f) at the Van De Graff (VdG) accelerator of the JRC-Geel using a fully digital data acquisition system. Neutrons from 252Cf(sf) were measured separately to quantify the neutron-scattering component due to surrounding shielding material and to determine the intrinsic detector efficiency. Prelimenary results on ν(A) and spectrum in correlation with FF properties are presented.

VERDI (VElocity foR Direct particle Identification) is a fission-fragment spectrometer recently put into operation at JRC-Geel. It allows measuring the kinetic energy and velocity of both fission fragments simultaneously. The velocity provides information about the pre-neutron mass of each fission fragment when isotropic prompt-neutron emission from the fragments is assumed. The kinetic energy, in combination with the velocity, provides the post-neutron mass. From the difference between pre- and post-neutron masses, the number of neutrons emitted by each fragment can be determined. Multiplicity as a function of fragment mass and total kinetic energy is one important ingredient, essential for understanding the sharing of excitation energy between fission fragments at scission, and may be used to benchmark nuclear de-excitation models. The VERDI spectrometer design is a compromise between geometrical efficiency and mass resolution. The spectrometer consists of an electron detector located close to the target and two arrays of silicon detectors, each located 50 cm away from the target. In the present configuration pre-neutron and post-neutron mass distributions are in good agreement with reference data were obtained. Our latest measurements performed with spontaneously fissioning 252Cf is presented along with the developed calibration procedure to obtain pulse height defect and plasma delay time corrections.

The Li-6(n,alpha)t reaction cross-section is an established standard due to its relatively high crosssection as well as its high Q-value. However, it is only considered a neutron standard up to 1 MeV, because in the neutron energy region 1-3 MeV there exist discrepancies of several per cents between recent measurements [1,2] and evaluated data files [3]. It has been speculated [4] that neglecting of the particle leaking effect might be part of the explanation why there is a disagreement in this region. Based on R-matrix calculations, in the region around 2 MeV, one also expects three excitation levels of Li-7 to significantly influence the cross section [5]. In order to resolve these discrepancies, we perform measurements at the GELINA facility at JRC-Geel with two Frisch-gridded ionisation chambers. The Li-6(n,alpha)t cross section is measured relative to the U-235(n,f) standard. In order to solve previous encountered problems [6], the setup has been modified and moved to a new flight path station. In this proceeding we show that several problems have been eliminated and discuss possible solutions to newly arisen problems, due to the changed experimental conditions. Preliminary results from new data taken during 2016 with the updated setup are presented., Updated setup from result 2016, DOI: 10.1051/epjconf/201612208006.

Numerous domains, in fundamental research as well as in applications, require the study of reactions induced by neutrons with energies from few MeV up to few tens of MeV. Reliable measurements also are necessary to improve the evaluated databases used by nuclear transport codes. This energy range covers a large number of topics like transmutation of nuclear waste, design of future fission and fusion reactors, nuclear medicine or test and development of new detectors. A new facility called Neutrons For Science (NFS) is being built for this purpose on the GANIL site at Caen (France). NFS is composed of a pulsed neutron beam for time-of-flight facility as well as irradiation stations for cross-section measurements. Neutrons will be produced by the interaction of deuteron and proton beams, delivered by the SPIRAL-2 linear accelerator, with thick or thin converters made of beryllium or lithium. Continuous and quasi-mono-energetic spectra will be available at NFS up to 40 MeV. In this fast energy region, the neutron flux is expected to be up to 2 orders of magnitude higher than at other existing time-of-flight facilities. In addition, irradiation stations for neutron-, proton- and deuteron-induced reactions will allow performing cross-section measurements by the activation technique. After a description of the facility and its characteristics, the experiments to be performed in the short and medium term will be presented.

Neutron-induced fission cross sections of 235U and 238U are widely used as standards for monitoring of neutron beams and fields. An absolute measurement of these cross sections at an absolute scale, i.e., versus the H(n,p) scattering cross section, is planned with the white neutron beam under construction at the Neutrons For Science (NFS) facility in GANIL. The experimental setup, based on PPACs and ΔE-ΔE-E telescopes containing Silicon and CsI(Tl) detectors, is described. The expected uncertainties are discussed.

With the Ion Guide Isotope Separator On-Line (IGISOL) facility, located at the University of Jyväskylä, products of nuclear reactions are separated by mass. The high resolving power of the JYFLTRAP Penning trap, with full separation of individual nuclides, capacitates the study of nuclides far from the line of stability. For the production of neutron-rich medium-heavy nuclides, fissioning of actinides is a feasible reaction. This can be achieved with protons from an in-house accelerator or, alternatively, with neutrons through the addition of a newly developed Be(p,xn)-converter. The hereby-obtained fission products are used in nuclear data measurements, for example fission yields, nuclear masses, Q-values and decay spectroscopy. Prior to separation, the ionized reaction products are stopped in a helium-filled gas cell, referred to as the ion-guide. In this work we present simulations of the stopping of fission products in an ion guide developed for neutron-induced fission. The production and extraction rates are evaluated and compared against experimental values.

An investigation of the stopping efficiency of fission products, in the new ion guide designed for ion production through neutron-induced fission at IGISOL in Jyväskylä, Finland, has been conducted. Our simulations take into account the new neutron converter, enabling measurements of neutron-induced fission yields, and thereby provide estimates of the obtained yields as a function of primary proton beam current. Different geometries, targets, and pressures, as well as models for the effective charge of the stopped ions were tested, and optimisations to the setup for higher yields are suggested. The predicted number of ions stopped in the gas lets us estimate the survival probability of the ions reaching the downstream measurements stations.

The main objective of the NordMin WASCIOUS project was to develop a technology concept for water conscious mining, where innovative water and tailings treatment technologies provide good-quality water for recycling and discharge and enable safe disposal or utilization of tailings. The work included a survey on current practices and requirements in Nordic mines and laboratory and pilot scale development of several technologies. Computational simulations of water treatment and recycling practices were performed for a feasibility study of some technology alternatives and technologies for dewatering of tailings were evaluated. As an important outcome of the project, a future Nordic research platform was established related to environmental issues in mining for the Nordic region, enabling exchange of ideas and collaboration in future project calls, and facilitating ideas for future projects.

This paper presents the ongoing analysis of two fission experiments. Both projects are part of the collaboration between the nuclear reactions group at Uppsala and the JRC-IRMM. The first experiment deals with the prompt fission neutron multiplicity in the thermal neutron induced fission of U-235(n,f). The second, on the fission fragment properties in the thermal fission of U-234(n,f). The prompt fission neutron multiplicity has been measured at the JRC-IRMM using two liquid scintillators in coincidence with an ionization chamber. The first experimental campaign focused on U-235(nth,f) whereas a second experimental campaign is foreseen later for the same reaction at 5.5 MeV. The goal is to investigate how the so-called saw-tooth shape changes as a function of fragment mass and excitation energy. Some harsh experimental conditions were experienced due to the large radiation background. The solution to this will be discussed along with preliminary results. In addition, the analysis of thermal neutron induced fission of U-234(n,f) will be discussed. Currently analysis of data is ongoing, originally taken at the ILL reactor. The experiment is of particular interest since no measurement exist of the mass and energy distributions for this system at thermal energies. One main problem encountered during analysis was the huge background of U-235(nth, f). Despite the negligible isotopic traces in the sample, the cross section difference is enormous. Solution to this parasitic background will be highlighted.

The Li-6(n,alpha) reaction cross-section is commonly used as a reference cross section. However, it is only considered a neutron standard up to 1 MeV. For higher energies, there are discrepancies of several per cents between recent measurements and evaluated data files. In order to extend and establish Li-6 (n,alpha) as a neutron standard above 1 MeV these discrepancies must be resolved. Our measurement at the GELINA facility at JRC-IRMM in Geel, Belgium is ongoing. We are using a double twin Frisch-grid setup to detect both a-particles from two Li-6 targets and fission products from two U-235 reference targets. Our targets have thick backings but are employed in pairs, one forward facing and one backward facing. In this way we still cover, in principle, a solid angle of 4 pi. We present some preliminary results showing that the existing cross-section data is well reproduced around the resonance at 240 keV. The final data taking will start in the beginning of 2016, when the GELINA facility goes online again after a few months of shut down.

This paper highlights some of the main activities related to fission of the nuclear reactions group at Uppsala University. The group is involved for instance in fission yield experiments at the IGISOL facility, cross-section measurements at the NFS facility, as well as fission dynamics studies at the IRMM JRC-EC. Moreover, work is ongoing on the Total Monte Carlo (TMC) methodology and on including the GEF fission code into the TALYS nuclear reaction code. Selected results from these projects are discussed.

At the Jyväskylä Ion Guide Isotope Separator On-Line (IGISOL) facility, independent fission yields are measured employing the Penning-trap technique. Fission products are produced, e.g. by impinging protons on a uranium target, and are stopped in a gas-filled chamber. The products are collected by a flow of He gas and guided through a mass separator to a Penning trap, where their masses are identified. This work investigates how fission-product properties, such as mass and energy, affect the ion stopping efficiency in the gas cell. The study was performed using the Geant4 toolkit and the SRIM code. The main results show a nearly mass-independent ion stopping with regard to the wide spread of ion masses and energies, with a proper choice of uranium target thickness. Although small variations were observed, in the order of 5%, the results are within the systematic uncertainties of the simulations. To optimize the stopping efficiency while reducing the systematic errors, different experimental parameters were varied; for instance material thicknesses and He gas pressure. Different parameters influence the mass dependence and could alter the mass dependencies in the ion stopping efficiency.

For nuclear modelling and improved evaluation of nuclear data, knowledge of fluctuations of the prompt neutron multiplicity as a function of incident neutron energy is requested for the major actinides 235U and 239Pu. Experimental investigations of the prompt fission neutron emission in resonance-neutron induced fission on 235U are taking place at the GELINA facility of the IRMM. The experiment employs an array of scintillation detectors (SCINTIA) in conjunction with a newly designed 3D position-sensitive twin Frisch-grid ionization chamber. In addition, the mass-dependent prompt neutron multiplicity, (A), has attracted particular attention. Recent, sophisticated nuclear fission models predict that the additional excitation energy, brought into the fission system at higher incident neutron energies, leads to an increased neutron multiplicity only for heavy fragments, as observed in the 237Np(n,f) reaction. A first feasibility study has been performed at the JRC-IRMM VdG accelerator to measure nu(A) for 235U(n,f).

The aim of this study is to consider the possibilities in reasonable and efficient water usage and high water recycling rate in mining and mineral processing industry. Wastewater treatment technologies for different mineral industry wastewaters are described and the basic chemistry behind the processes explained. The thesis also describes the reasons for water use in mineral extraction processes, the wastes formed in the processing of ore and minerals, the common reagents used in mineral processing and the best available techniques considering mining activities. Water is widely used in mining and minerals industry: for processing and transporting of ore and waste, minerals separation, dust suppression, washing of equipment, smelter refractory cooling systems and human consumption. Both economic and environmental considerations make the recycling and re-use of water an absolute necessity. The industry has made much progress in developing close-circuit approaches that maximize water conservation, and responsible management of water is a key ingredient in ensuring that mining companies’ contribution to sustainable development is positive over the long term. Factors that have led to increasing recycle of the used process water are following: water use of the mineral processing plants may represent a large proportion of the local water resources, the production and transportation of fresh water are usually expensive and the effluents from the processing operations are potentially harmful to the environment. Common characteristic of mineral processing water is the presence of ions and chemical compounds with a high pollution potential. One of the most satisfactory ways of dealing with this problem is the total recycling of reject waters, but several technical aspects influence the extent to which recycling can be performed. The chemistry of the system could affect the process efficiency, which applies especially to flotation which is principally governed by the chemistry, Työn tavoitteena on edistää kohtuullista ja tehokasta veden käyttöä ja veden kierrätystä kaivos- ja mineraaliteollisuudessa mahdollisimman ympäristöystävällisiä ja taloudellisia menetelmiä hyödyntäen. Työssä kuvaillaan erilaisille mineraaliteollisuuden jätevesille sopivia jäteveden käsittelyteknologioita sekä käsittelyyn ja kierrätykseen liittyvää kemiaa. Työ tarkastelee myös vedenkäytön syitä mineraaliteollisuudessa, malmin ja mineraalien prosessoinnissa syntyviä jätteitä, yleisimpiä reagensseja sekä parhaita mahdollisia teknologioita kaivosteollisuudessa. Vettä käytetään kaivos- ja mineraaliteollisuudessa laajasti: malmin ja jätteen prosessointiin ja kuljetukseen, mineraalien erotukseen, pölynestoon, laitteistojen pesuun, sulattojen jäähdytysjärjestelmiin ja ihmisten käyttöön. Veden uudelleenkäyttö ja kierrätys ovat välttämättömiä niin taloudellisista kuin ympäristöllisistäkin syistä. Teollisuudenala onkin edistynyt suuresti suljetun prosessin kehittämisessä. Veden vastuullinen käsittely on avainasemassa tarkasteltaessa kaivosyritysten vaikutusta kestävään kehitykseen pitkällä aikavälillä. Lisääntyneeseen prosessiveden kierrätykseen ovat vaikuttaneet useat tekijät. Mineraalien prosessointilaitosten vedenkäyttö voi edustaa suurta osaa paikallisista vesiresursseista, makean veden tuottaminen ja kuljettaminen on yleensä kallista, ja lisäksi prosessien jätevedet ovat mahdollisesti haitallisia ympäristölle. Mineraaliteollisuuden prosessivedet sisältävät yleensä saastumista aiheuttavia ioneja ja kemiallisia yhdisteitä. Jätevesien täydellinen kierrätys on yksi parhaimpia keinoja tämän ongelman ratkaisemiseksi, mutta useat tekniset näkökulmat vaikuttavat saavutettavaan kierrätysasteeseen. Systeemin kemialliset ominaisuudet voivat vaikuttaa prosessin tehokkuuteen, mikä pätee erityisesti vaahdotukseen, jota malmin kemialliset ominaisuudet pääasiassa säätelevät. Jokaisella prosessivaiheella on tietty veden kemiallinen koostumus, jolla prosessia voidaan ongelmitta operoida. V

At the IGISOL-JYFLTRAP facility, fission mass yields can be studied at high precision. Fission fragments from a U target are passing through a Ni foil and entering a gas filled chamber. The collected fragments are guided through a mass separator to a Penning trap where their masses are identified. This simulation work focuses on how different fission fragment properties (mass, charge and energy) affect the stopping efficiency in the gas cell. In addition, different experimental parameters are varied (e. g. U and Ni thickness and He gas pressure) to study their impact on the stopping efficiency. The simulations were performed using the Geant4 package and the SRIM code. The main results suggest a small variation in the stopping efficiency as a function of mass, charge and kinetic energy. It is predicted that heavy fragments are stopped about 9% less efficiently than the light fragments. However it was found that the properties of the U, Ni and the He gas influences this behavior. Hence it could be possible to optimize the efficiency.

The Neutrons For Science (NFS) facility is a component of SPIRAL-2 laboratory under construction at Caen (France). SPIRAL-2 is dedicated to the production of high intensity Radioactive Ions Beams (RIB). It is based on a high-power linear accelerator (LINAG) to accelerate deuterons beams in order to produce neutrons by breakup reactions on a C converter. These neutrons will induce fission in U-238 for production of radioactive isotopes. Additionally to the RIB production, the proton and deuteron beams delivered by the accelerator will be used in the NFS facility. NFS is composed of a pulsed neutron beam and irradiation stations for cross-section measurements and material studies. The beams delivered by the LINAG will allow producing intense neutron beams in the 100 keV-40 MeV energy range with either a continuous or quasi-mono-energetic spectrum. At NFS available average fluxes will be up to 2 orders of magnitude higher than those of other existing time-of-flight facilities in the 1 MeV - 40 MeV range. NFS will be a very powerful tool for fundamental physics and application related research in support of the transmutation of nuclear waste, design of future fission and fusion reactors, nuclear medicine or test and development of new detectors. The facility and its characteristics are described, and several examples of the first potential experiments are presented.

The Medley detector setup is planned to be moved to and used at the new neutron facility NFS where measurements of light-ion production and fission cross-sections are planned at 1-40 MeV. Medley has eight detector telescopes providing Delta E-Delta E-E data, each consisting of two silicon detectors and a CsI(Tl) detector at the back. The telescope setup can be rotated and arranged to cover any angle. Medley has previously been used in many measurements at The Svedberg Laboratory (TSL) in Uppsala mainly with a quasi-mono-energetic neutron beam at 96 and 175 MeV. To be able to do measurements at NFS, which will have a white neutron beam, Medley needs to detect the reaction products with a high timing resolution providing the ToF of the primary neutron. In this paper we discuss the design of the Medley upgrade along with simulations of the setup. We explore the use of Parallel Plate Avalanche Counters (PPACs) which work very well for detecting fission fragments but require more consideration for detecting deeply penetrating particles.

We have measured double-differential cross sections for 175 MeV quasi-monoenergetic neutrons on oxygen. The detector setup used in MEDLEY consists of eight Si-Si-CsI telescopes designed to detect light ions (up to A=4), with a low-energy threshold and over an angular domain ranging from 20 degrees to 160 degrees, in steps of 20 degrees. The Delta E - E technique is used to identify the light ions. Suppression of events induced by neutrons in the low-energy tail of the neutron field is achieved by time-of-flight techniques. The data are normalised relative to elastic np scattering measured in one of the telescopes at 20 degrees. We present preliminary double-differential production cross sections for protons, deuterons and a particles and compare them with theoretical reaction model calculations.