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The fission process still remains a main factor that determines the stability of the atomic nucleus of heaviest elements. Fission half-lives vary over a wide range, 10−19−1024 s. Present experimental techniques for the synthesis of the superheavy elements that usually measure α-decay chains are sensitive only in a limited range of half-lives, often 10−5−103 s. In the past years, measurement techniques for very short-lived and very long-lived nuclei were significantly improved at the gas-filled recoil separator TASCA at GSI Darmstadt. Recently, several experimental studies of fission-related phenomena have successfully been performed. In this paper, results on 254−256Rf and 266Lr are presented and corresponding factors for retarding the fission process are discussed.

An experiment aiming to study the shape coexistence in 193Bi has been performed at the Accelerator laboratory of the University of Jyväskylä, Finland (JYFL). Many new states have been found, hugely extending the previously known level scheme of 193Bi. The Iπ=292+${I^\pi } = {{{29} \over 2}^ + }$ member of the πi13/2 band de-excites also to the previously, only tentatively placed long-lived isomeric state. This link determines the energy of the isomeric state to be 2260(1) keV and suggests a spin and parity of (272+)$\left( {{{{{27} \over 2}}^ + }} \right)$. The half-life of the isomeric state was measured to be 84.4(6) µs. A level structure on top of this isomeric state was constructed. However, transition directly depopulating this state could not be identified. A superdeformed band almost identical to that present in the neighboring isotope 191Bi has been identified.

Excited states in the nuclei 83As and 84,86Se have been studied via prompt γ-ray spectroscopy. The nuclei were produced by the proton-induced fission of a 238U target, at the accelerator of the University of Jyväskylä. The JUROGAM-II array was used to detect prompt γ-rays and a triple-γ coincidence analysis performed. A comparison of the N = 50 nuclei with shell-model calculations reproduces the low-lying states in 83As and 84Se well. The inclusion of particle-hole excitations is necessary to correctly describe the states above ∼ 3.5 MeV.

Prompt γ-ray spectroscopy of neutron-rich cadmium isotopes has been performed. The nuclei of interest have been populated via a 25-MeV, proton-induced fission of the 238U thick target and prompt γ-rays measured using the multi-detector HPGe array JUROGAM II. New high-spin decays have been observed and placed in the level scheme using triple coincidence gates. The experimental results are compared to shell-model calculations and show good agreement.

A nuclear spectroscopy experiment was conducted to study α-decay chains stemming from isotopes of flerovium (element Z=114). An upgraded TASISpec decay station was placed behind the gas-filled separator TASCA at the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt, Germany. The fusion-evaporation reactions ^{48}Ca+^{242}Pu and ^{48}Ca+^{244}Pu provided a total of 32 flerovium-candidate decay chains, of which two and eleven were firmly assigned to ^{286}Fl and ^{288}Fl, respectively. A prompt coincidence between a 9.60(1)-MeV α particle event and a 0.36(1)-MeV conversion electron marked the first observation of an excited state in an even-even isotope of the heaviest man-made elements, namely ^{282}Cn. Spectroscopy of ^{288}Fl decay chains fixed Q_{α}=10.06(1)  MeV. In one case, a Q_{α}=9.46(1)-MeV decay from ^{284}Cn into ^{280}Ds was observed, with ^{280}Ds fissioning after only 518  μs. The impact of these findings, aggregated with existing data on decay chains of ^{286,288}Fl, on the size of an anticipated shell gap at proton number Z=114 is discussed in light of predictions from two beyond-mean-field calculations, which take into account triaxial deformation.

A nuclear spectroscopy experiment was conducted to study α-decay chains stemming from isotopes of flerovium (element Z=114). An upgraded TASISpec decay station was placed behind the gas-filled separator TASCA at the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt, Germany. The fusion-evaporation reactions ^{48}Ca+^{242}Pu and ^{48}Ca+^{244}Pu provided a total of 32 flerovium-candidate decay chains, of which two and eleven were firmly assigned to ^{286}Fl and ^{288}Fl, respectively. A prompt coincidence between a 9.60(1)-MeV α particle event and a 0.36(1)-MeV conversion electron marked the first observation of an excited state in an even-even isotope of the heaviest man-made elements, namely ^{282}Cn. Spectroscopy of ^{288}Fl decay chains fixed Q_{α}=10.06(1)  MeV. In one case, a Q_{α}=9.46(1)-MeV decay from ^{284}Cn into ^{280}Ds was observed, with ^{280}Ds fissioning after only 518  μs. The impact of these findings, aggregated with existing data on decay chains of ^{286,288}Fl, on the size of an anticipated shell gap at proton number Z=114 is discussed in light of predictions from two beyond-mean-field calculations, which take into account triaxial deformation.

An upgraded TASISpec setup, with the addition of a veto DSSD and the new Compex detector-germanium array, has been employed with the gas-filled recoil separator TASCA at the GSI Helmholtzzentrum für Schwerionenforschung Darmstadt, to study flerovium (element 114) decay chains. The detector upgrades along with development of new analytical techniques have improved the sensitivity of the TASISpec setup for measuring α-photon coincidences. These improvements have been assessed with test reactions. The reaction 48Ca+206,207Pb was used for verification of experimental parameters such as transmission to implantation DSSD and target-segment to α-decay correlations. The reaction 48Ca+ nat Hf was used to produce several short-lived nuclei with multiple-α decay chains to investigate pile-up event deconvolution.

The heaviest currently known nuclei, which have up to 118 protons, have been produced in Ca48 induced reactions with actinide targets. Among them, the element tennessine (Ts), which has 117 protons, has been synthesized by fusing Ca48 with the radioactive target Bk249, which has a half-life of 327 d. The experiment was performed at the gas-filled recoil separator TASCA. Two long and two short α decay chains were observed. The long chains were attributed to the decay of Ts294. The possible origin of the short-decay chains is discussed in comparison with the known experimental data. They are found to fit with the decay chain patterns attributed to Ts293. The present experimental results confirm the previous findings at the Dubna Gas-Filled Recoil Separator on the decay chains originating from the nuclei assigned to Ts.

The heaviest currently known nuclei, which have up to 118 protons, have been produced in Ca48 induced reactions with actinide targets. Among them, the element tennessine (Ts), which has 117 protons, has been synthesized by fusing Ca48 with the radioactive target Bk249, which has a half-life of 327 d. The experiment was performed at the gas-filled recoil separator TASCA. Two long and two short α decay chains were observed. The long chains were attributed to the decay of Ts294. The possible origin of the short-decay chains is discussed in comparison with the known experimental data. They are found to fit with the decay chain patterns attributed to Ts293. The present experimental results confirm the previous findings at the Dubna Gas-Filled Recoil Separator on the decay chains originating from the nuclei assigned to Ts.

In the boreal region, peatlanda forests are a significant resource of timber. Under pressure from a growing bioeconomy and climate change, timber harvesting is increasingly occurring over unfrozen soils. This is likely to cause disturbance in the soil biogeochemistry. We studied the impact of machinery-induced soil disturbance on the vegetation, microbes, and soil biogeochemistry of drained boreal peatland forests caused by machinery traffic during thinning operations. To assess potential recovery, we sampled six sites that ranged in time since thinning from a few months to 15 years. Soil disturbance directly decreased moss biomass and led to an increase in sedge cover and a decrease in root production. Moreover, soil C[O.sub.2] production potential, and soil C[O.sub.2] and C[H.sub.4] concentrations were greater in recently disturbed areas than in the control areas. In contrast, C[O.sub.2] and C[H.sub.4] emissions, microbial biomass and structure, and the decomposition rate of cellulose appeared to be uncoupled and did not show signs of impact. While the impacted properties varied in their rate of recovery, they all fully recovered within 15 years covered by our chronosequence study. Conclusively, drained boreal peatlands appeared to have high biological resilience to soil disturbance caused by forest machinery during thinning operations. Key words: peat, drained peatlands, harvesting, PLFA, microbial biomass, roots, decomposition, soil C[O.sub.2], C[H.sub.4] and [N.sub.2]O concentrations, soil C[O.sub.2] and C[H.sub.4] emissions. En region boreale, les forets de tourbiere constituent une importante ressource en bois. Soumise a la pression d'une bioeconomie croissante et du changement climatique, la recolte de bois s'etend de plus en plus sur des sols degeles. Cela risque de perturber la biogeochimie du sol. Nous avons etudie l'impact de la perturbation du sol causee par la machinerie sur la vegetation, les microorganismes et la biogeochimie du sol dans les forets de tourbiere boreale drainee due a la circulation de la machinerie lors des operations d'eclaircie. Afin d'evaluer le potentiel de recuperation, nous avons echantillonne six stations ou le temps ecoule depuis l'eclaircie variait de quelques mois a 15 ans. La perturbation du sol a directement reduit la biomasse de la mousse et entraine une augmentation du couvert de carex et une diminution de la production de racines. De plus, la production potentielle de dioxyde de carbone (C[O.sub.2]) dans le sol et les concentrations de C[O.sub.2] et de methane (C[H.sub.4]) dans le sol etaient plus elevees dans les zones recemment perturbees que dans les zones temoins. Par contre, les emissions de C[O.sub.2] et de C[H.sub.4], la structure et la biomasse microbiennes ainsi que le taux de decomposition de la cellulose semblaient decouples et ne montraient aucun signe d'impact. Tandis que le taux de recuperation des proprietes qui avaient ete affectees variait, elles ont toutes recupere pendant les 15 annees couvertes par la chronosequence que nous avons etudiee. Les tourbieres boreales drainees semblent definitivement posseder une grande resilience biologique face aux perturbations du sol causees par la machinerie lors des operations d'eclaircie. [Traduit par la Redaction] Mots-cles : tourbe, tourbieres drainees, recolte, acides gras phospholipidiques (PLFA), biomasse microbienne, racines, decomposition, concentrations de C[O.sub.2], de C[H.sub.4] et d'oxyde de diazote ([N.sub.2]O) dans le sol, emissions de C[O.sub.2] et de C[H.sub.4] provenant du sol., 1. Introduction Forested peatlands are widespread in the boreal zone; approximately 24% of the total boreal forest area is classified as peatlands (Wieder et al. 2006). A large portion of [...]

The isotopic distribution of nuclei produced in the 50Ti + 249Cf reaction has been studied at the gas-filled recoil separator TASCA at GSI Darmstadt, which separates ions according to differences in magnetic rigidity. The bombardment was performed at an energy around the Bass barrier and with the TASCA magnetic fields set for collecting fusion-evaporation reaction products. Fifty-three isotopes located “north-east” of 208Pb were identified as recoiling products formed in non-fusion channels of the reaction. These recoils were implanted with energies in two distinct ranges; besides one with higher energy, a significant low-energy contribution was identified. The latter observation was not expected to occur according to kinematics of the known types of reactions, namely quasi-elastic, multi-nucleon transfer, deep-inelastic collisions or quasifission. The present observations are discussed within the framework of two-body kinematics passing through the formation of a composite system.

The isotopic distribution of nuclei produced in the 50Ti + 249Cf reaction has been studied at the gas-filled recoil separator TASCA at GSI Darmstadt, which separates ions according to differences in magnetic rigidity. The bombardment was performed at an energy around the Bass barrier and with the TASCA magnetic fields set for collecting fusion-evaporation reaction products. Fifty-three isotopes located “north-east” of 208Pb were identified as recoiling products formed in non-fusion channels of the reaction. These recoils were implanted with energies in two distinct ranges; besides one with higher energy, a significant low-energy contribution was identified. The latter observation was not expected to occur according to kinematics of the known types of reactions, namely quasi-elastic, multi-nucleon transfer, deep-inelastic collisions or quasifission. The present observations are discussed within the framework of two-body kinematics passing through the formation of a composite system.

Forestry-drained peatlands occupy approximately 15 million ha in boreal and temperate zones. In Finland, they represent almost one-fourth of the total forest area. They are subjected to the same harvesting operations as upland forests. Although the soil deformation caused by timber harvesting is well documented in upland forests, the knowledge on the soil disturbance induced by the harvesting machinery on peat soils is still lacking. To address this, we collected soil samples from six peatland sites that were thinned using a harvester-forwarder combination. Peat samples were taken from the trails formed by the machinery and outside the trails to a depth of 10 cm. To assess the recovery of soil properties after the disturbance, we sampled sites along a chronosequence with respect to time since harvesting. Soil deformation under the machinery appeared to increase the bulk density and field capacity of peat and decrease its total porosity; however, disturbed plots and control plots started to resemble each other in their soil properties within 15 years. The results imply that peat soil is sensitive to disturbance but has a high recovery potential. Key words: drained peatlands, forest harvesting, bulk density, water retention, pore size distribution. Les tourbieres drainees pour l'exploitation forestiere occupent environ 15 millions d'hectares en regions boreale et temperee. En Finlande, elles representent presque 25 % de la superficie forestiere totale. Elles sont soumises aux memes operations forestieres que les forets en milieu sec. Bien que la deformation du sol causee par l'exploitation forestiere soit bien documentee dans les forets en milieu sec, les connaissances sur la perturbation du sol causee par la machinerie forestiere sur les sols tourbeux sont encore deficientes. Pour aborder cette question, nous avons collecte des echantillons de sol dans six tourbieres eclaircies en utilisant une combinaison d'abatteuse et porteur. Des echantillons de tourbe ont ete preleves dans les sentiers crees par la machinerie et a l'exterieur des sentiers jusqu'a une profondeur de 10 cm. Pour evaluer la recuperation des proprietes du sol a la suite de la perturbation, nous avons echantillonne des stations le long d'une chronosequence representant le temps ecoule depuis la recolte. La deformation du sol sous la machinerie semblait augmenter la masse volumique apparente et la capacite au champ de la tourbe et diminuer sa porosite totale. Cependant, les proprietes du sol des parcelles perturbees et temoins ont commence a se ressembler apres moins de 15 ans. Les resultats indiquent que les sols tourbeux sont sensibles aux perturbations mais qu'ils ont un potentiel de recuperation eleve. [Traduit par la Redaction] Mots-cles: tourbieres drainees, exploitation forestiere, masse volumique apparente, retention d'eau, distribution de la dimension des pores., 1. Introduction Sustainable forest management aims at the utilization of forests in a way that maintains and enhances the long-term health and productivity of the forest ecosystem (Schanz 2004). Soil [...]