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This study investigates the response of synchronous dynamic random access memories to energetic electrons and especially the possibility of electrons to cause stuck bits in these memories. Three different memories with different node sizes (63, 72, and 110 nm) were tested. Electrons with energies between 6 and 200 MeV were used at RADiation Effects Facility (RADEF) in Jyvaskyla, Finland, and at Very energetic Electron facility for Space Planetary Exploration missions in harsh Radiative environments (VESPER) in The European Organization for Nuclear Research (CERN), Switzerland. Photon irradiation was also performed in Jyvaskyla. In these irradiation tests, stuck bits originating from electron-induced single-event effects (SEEs) were found, as well as single bit-flips from single electrons. To the best knowledge of the authors, this is the first time that stuck bits from single-electron events have been reported in the literature. It is argued in the article that the single-event bit-flips and stuck bits are caused by the same damage mechanism, which would be large displacement damage clusters, and that the two different fault modes represent different amounts of damage to the memory cell. After a large particle fluence, a rapid increase in the error rate was observed, originating from the accumulation of smaller displacement damage clusters in the memory cells. The 110-nm memory was a candidate component to fly on the European Space Agency (ESA) JUpiter ICy moons Explorer (JUICE) mission, so the SEE cross section as a function of electron energy was compared to the expected electron environment encountered by JUICE to estimate the error rates during the mission.

We investigate, through measurements and simulations, the possible direct ionization impact on the accelerator soft-error rate (SER), not considered in standard qualification approaches. Results show that, for a broad variety of state-of-the-art commercial components considered in the 65-16-nm technological range, indirect ionization is still expected to dominate the overall SER in the accelerator mixed-field. However, the derived critical charges of the most sensitive parts, corresponding to ~0.7 fC, are expected to be at the limit of rapid direct ionization dominance and soft-error increase., This work was supported in part by the European Union’s Horizon 2020 Research and Innovation Program under Grant 721624 and in part by the European Space Agency (ESA/ESTEC) at the University of Jyväskylä under Contract 4000124504/18/NL/KML/zk

The design, integration, testing, and launch of the first Finnish satellite Aalto-1 is briefly presented in this paper. Aalto-1, a three-unit CubeSat, launched into Sun-synchronous polar orbit at an altitude of approximately 500 km, is operational since June 2017. It carries three experimental payloads: Aalto Spectral Imager (AaSI), Radiation Monitor (RADMON), and Electrostatic Plasma Brake (EPB). AaSI is a hyperspectral imager in visible and near-infrared (NIR) wavelength bands, RADMON is an energetic particle detector and EPB is a de-orbiting technology demonstration payload. The platform was designed to accommodate multiple payloads while ensuring sufficient data, power, radio, mechanical and electrical interfaces. The design strategy of platform and payload subsystems consists of in-house development and commercial subsystems. The CubeSat Assembly, Integration & Test (AIT) followed Flatsat -- Engineering-Qualification Model (EQM) -- Flight Model (FM) model philosophy for qualification and acceptance. The paper briefly describes the design approach of platform and payload subsystems, their integration and test campaigns, and spacecraft launch. The paper also describes the ground segment & services that were developed by the Aalto-1 team., 41 pages, 16 figures, accepted to Acta Astronautica, 2021

International audience; Functional verification schemes at a level different from component-level testing are emerging as a cost-effective tool for those space systems for which the risk associated with a lower level of assurance can be accepted. Despite the promising potential, system-level radiation testing can be applied to the functional verification of systems under restricted intrinsic boundaries. Most of them are related to the use of hadrons as opposed to heavy ions. Hadrons are preferred for the irradiation of any bulky system, in general, because of their deeper penetration capabilities. General guidelines about the test preparation and procedure for a high-level radiation test are provided to allow understanding which information can be extracted from these kinds of functional verification schemes in order to compare them with the reliability and availability requirements. The use of a general scaling factor for the observed high-level cross sections allows converting test cross sections into orbit rates.

Radiation-induced emission of doped sol-gel silica glass samples was investigated under a pulsed 20-MeV electron beam. The studied samples were drawn rods doped with cerium, copper, or gadolinium ions, which were connected to multimode pure-silica core fibers to transport the induced luminescence from the irradiation area to a signal readout system. The luminescence pulses in the samples induced by the electron bunches were studied as a function of deposited dose per electron bunch. All the investigated samples were found to have a linear response in terms of luminescence as a function of electron bunch sizes between 10−5 Gy/bunch and 1.5×10−2 Gy/bunch. The presented results show that these types of doped silica rods can be used for monitoring a pulsed electron beam, as well as to evaluate the dose deposited by the individual electron bunches. The electron accelerator used in the experiment was a medical type used for radiation therapy treatments, and these silica rod samples show high potential for dosimetry in radiotherapy contexts.

Publisher Copyright: © 2021 ESA and CNES We have studied how high-energy electron irradiation (12 MeV, total dose 66 krad(Si)) and long term humidity exposure (75%, 75 °C, 500 hours) influence the induced junction black silicon or planar photodiode characteristics. In our case, the induced junction is formed using n-type silicon and atomic-layer deposited aluminum oxide (Al2O3), which contains a large negative fixed charge. We compare the results with corresponding planar pn-junction detectors passivated with either with silicon dioxide (SiO2) or Al2O3. The results show that the induced junction detectors remain stable as their responsivity remains nearly unaffected during the electron beam irradiation. On the other hand, the SiO2 passivated counterparts that included conventional pn-junction degrade heavily, which is seen as strongly reduced UV response. Similarly, after humidity test the response of the induced junction detector remains unaffected, while the pn-junction detectors passivated with SiO2 degrade significantly, for instance, the response at 200 nm reduces to 50% from the original value. Interestingly, the pn-junction detectors passivated with Al2O3 exhibit no degradation of UV response, indicating that the surface passivation properties of Al2O3 are more stable than SiO2 under the studied conditions. This phenomenon is further confirmed with PC1D simulations suggesting that the UV degradation results from increased surface recombination velocity. To conclude, the results presented here suggest that black silicon photodiodes containing Al2O3-based induced junction are highly promising alternatives for applications that require the best performance and long-term stability under ionizing and humid conditions.

Treatment of brain cancer, glioma, can cause cognitive impairment as a side‐effect, possibly because it disrupts the integrity of the hippocampus, a structure vital for normal memory. Radiotherapy is commonly used to treat glioma, but the effects of irradiation on the brain are still poorly understood, and other biological effects have not been extensively studied. Here we exposed healthy adult male rats to small and moderate‐dose irradiation of the head. We found no effect of irradiation on systemic inflammation, weight gain or gut microbiota diversity, although it increased the abundance of Bacteroidaceae family, namely Bacteroides genus in the gut microbiota. Irradiation had no effect on long‐term potentiation in the CA3‐CA1 synapse or endogenous hippocampal electrophysiology, but it did reduce adult hippocampal neurogenesis and impaired short‐term spatial recognition memory. However, no overall cognitive impairment was observed. To summarize, our results suggest that in adult male rats head irradiation does not compromize health or cognition overall even though the number of new, adult‐born hippocampal neurons is decreased. Thus, the sole effects of head irradiation on the body, brain and cognition might be less harmful than previously thought, and the cognitive decline experienced by cancer patients might originate from physiological and mental effects of the disease itself. Therefore, and to increase the translational value of animal studies, the effects of irradiation should be studied together with cancer, in older animals, using varying irradiation protocols and doses. peerReviewed

International audience; The R2E project at CERN has tested a few commercial SRAMs and a custom-designed SRAM, whose data are complementary to various scientific publications. The experimental data include low- and high-energy protons, heavy ions, thermal, intermediate- and high-energy neutrons, high-energy electrons and high-energy pions.

The advantages of silicon carbide (SiC) power MOSFETs make this technology attractive for space, avionics and high-energy accelerator applications. However, the current commercial technologies are still susceptible to Single Event Effects (SEEs) and latent damages induced by the radiation environment. Two types of latent damage were experimentally observed in commercial SiC power MOSFETs exposed to heavy-ions. One is observed at bias voltages just below the degradation onset and it involves the gate oxide. The other damage type is observed at bias voltages below the Single Event Burnout (SEB) limit, and it is attributed to alterations of the SiC crystal-lattice. Focused ion beam (FIB) and scanning electron microscopy (SEM) were used to investigate the damage site. Finally, a summary of the different types of damage induced by the heavy ion in SiC MOSFETs is given as a function of the ion LET and operational bias., Microelectronics Reliability, 128, ISSN:0026-2714, ISSN:1872-941X

International audience; This paper identifies the failure modes of a commercial 130-nm ferroelectric random access memory. The devices were irradiated with heavy-ion and pulsed focused X-ray beams. Various failure modes are observed, which generate characteristic error patterns, affecting isolated bits, words, groups of pages, and sometimes entire regions of the memory array. The underlying mechanisms are discussed.

Studies of heavy-ion induced single event effect (SEE) on space electronics are necessary to verify the operation of the components in the harsh radiation environment. These studies are conducted by using high-energy heavy-ion beams to simulate the radiation effects in space. The ion beams are accelerated as so-called ion cocktails, containing several ion beam species with similar mass-to-charge ratio, covering a wide range of linear energy transfer (LET) values also present in space. The use of cocktails enables fast switching between beam species during testing. Production of these high-energy ion cocktails poses challenging requirements to the ion sources because in most laboratories reaching the necessary beam energies requires very high charge state ions. There are two main technologies producing these beams: The electron beam ion source EBIS and the electron cyclotron resonance ion source ECRIS. The EBIS is most suitable for pulsed accelerators, while ECRIS is most suitable for use with cyclotrons, which are the most common accelerators used in these applications. At the Accelerator Laboratory of the University of Jyvaskyla (JYFL), radiation effects testing is currently performed using a K130 cyclotron and a 14 GHz ECRIS at a beam energy of 9.3 MeV/u. A new 18 GHz ECRIS, pushing the limits of the normal conducting ECR technology is under development at JYFL. The performances of existing 18 GHz ion sources have been compared, and based on this analysis, a 16.2 MeV/u beam cocktail with 1999 MeV 126 Xe 44 + being the most challenging component to has been chosen for development at JYFL. The properties of the suggested beam cocktail are introduced and discussed.

A new experimental system for precise determination of electronic stopping powers of heavy ions has been set up at the accelerator laboratory of the University of Jyvaskyla. The new setup, combining an established B-ToF system and an array of calorimetric low temperature detectors (CLTDs), has been used for the determination of electronic stopping powers of 0.05–1 MeV/u 131Xe ions in carbon, nickel and gold. Thereby advantage of the improved linearity and energy resolution of CLTDs as compared to the previously used ionization detector was taken to reduce energy calibration errors and to increase sensitivity for the energy loss determination, in particular at very low energies. The total uncertainties of 3–4% for C- and Ni-targets, and 5–7% for Au-targets, respectively, are dominated by the target properties, i.e. thickness determination and inhomogeneities. The results are compared to data from literature and to predictions of different theoretical computer codes. In the high energy part of the examined energy range the results are in good agreement with previously published data, while new stopping power data for very heavy ions in different Z2-materials have been obtained at lower energies. Moreover, unexpectedly strong channeling effects for the transmission of the 131Xe ions in thin, partly polycrystalline nickel and gold target foils have been observed and investigated.

International audience; Stuck and weakened bits in the ISSI 512 Mb SDRAM was investigated in irradiation experiments with a heavy ion microbeam in the GSI facility. Delidded memories were tested in gold and calcium ion beams at 4.8 MeV/u, and stuck bits in the memory from the irradiation were investigated. To study weakened but not fully stuck bits after irradiation, parameters such as the refresh frequency of the memories was varied. The effect on the number of stuck bits from reading and writing the memory was studied, as well as the effect from waiting a time span between writing and reading the memory. These parameters were found to matter in the observed number of errors in the memory. Data on the findings from the microbeam irradiation from tests with different test modes are presented in this paper regarding suck bits and bit upsets. The test modes include dynamic March test and data retention tests with only refresh operations during irradiation.

The stability of black silicon induced junction photodetectors under high-energy irradiation was tested with 11 MeV protons and 12 MeV electrons using fluence of 1 ⋅ 10 10 protons/cm2 and dose of 67 krad(Si) for protons and electrons, respectively. The energies and dose levels were selected to test radiation levels relevant for space applications. The degradation was evaluated through dark current and external quantum efficiency changes during (within 1 h after each step) and after (some days after) full irradiation sequences. Furthermore, the black silicon photodetectors were compared to planar silicon induced junction and planar silicon pn-junction photodetectors to assess the contribution from both black silicon and semiconductor junction characteristics. The calculated radiation damage factors of all types of studied detectors were in agreement with values previously published in literature. The external quantum efficiency results demonstrated that the combination of black silicon surface and aluminum oxide induced junction provides a good radiation hardness against the used proton and electron doses showing degradation only in the near infrared region due to bulk damage. The pn-junction photodetectors with silicon dioxide passivation exhibited significant degradation also in the ultraviolet responsivity after electron irradiation.

Experimental determination of elastic constants of anisotropic composite laminates in all orthogonal directions is generally a complex process. In this paper a simple direct technique to determine a broad set of elastic moduli is presented based on compression testing of a prism sample. Digital image correlation is used to measure the full-field deformations that allow the determination of Young's moduli and all six Poisson's ratios for the three orthogonal directions based on a single sample. Finite element model is used in evaluation of the effect of friction on the measured properties. In addition to quantitative characterization of the material properties, local strain mapping is used in qualitative evaluation of the sample structures. acceptedVersion

A new data acquisition system, ToF-DAQ, has been developed for a ToF-ERDA telescope and other ToF-E and ToF-ToF measurement systems. ToF-DAQ combines an analogue electronics front-end to asynchronous time stamped data acquisition by means of a FPGA device. Coincidences are sought solely in software based on the timestamps. Timestamping offers more options for data analysis as coincidence events can be built also in offline analysis. The system utilises a National Instruments R-series FPGA device and a Windows PC as a host computer. Both the FPGA code and the host software were developed using the National Instruments LabVIEW graphical programming environment. Up to eight NIM ADCs can be handled by a single FPGA. The host computer and the FPGA can process total continuous count rates of over 750000 counts/s with a timestamping resolution of 8.33 ns. peerReviewed

This work presents experimental Single Event Gate Rupture (SEGR) data for Metal–Insulator–Semiconductor (MIS) devices, where the gate dielectrics are made of stacked SiO2–Si3N4 structures. A semi-empirical model for predicting the critical gate voltage in these structures under heavy-ion exposure is first proposed. Then interrelationship between SEGR cross- section and heavy-ion induced energy deposition probability in thin dielectric layers is discussed. Qualitative connection between the energy deposition in the dielectric and the SEGR is proposed. peerReviewed

Calorimetric low temperature detectors (CLTD’s) have been included in a B-ToF setup, that has already been used several times to perform energy loss measurements at the accelerator laboratory of the University of Jyvaskyla. The new experimental setup enabled a precise determination of stopping power data for 0.05–1 MeV/u $$^{131}$$ Xe ions in carbon, nickel and gold. The results are presented and compared to data from literature and theoretical predictions. As a by-product, due to the excellent energy resolution of CLTD’s for heavy ions at low energies, an observation of channeling effects in very thin polycrystalline targets and a determination of the channeling energy loss for 0.1–0.5 MeV/u $$^{131}$$ Xe-ions in Ni- and Au-absorbers was possible.

We study the effects of high-energy electrons on advanced NAND Flash memories with multi-level and single-level cell architecture. We analyze the error rate in floating gate cells as a function of electron energy, evaluate the impact of total ionizing dose, and discuss the physical origin of the observed behavior.

Four pulsed-laser single-event effects systems, differing in wavelength and pulse width, were used to generate single event transients in a large-area silicon photodiode and an operational amplifier (LM124) to determine how transient amplitude and charge collection varied among the different systems. The optical wavelength and the focused spot size are the primary factors influencing the resultant charge density profile. In the large-area photodiode the transients can be distorted by high charge-injection densities that occur for tightly focused, higher energy optical pulses. When the incident laser-pulse energies are corrected for reflection losses and photon efficiency, with collection depth as a floating parameter (to account for diffusion), the photodiode data for all four devices lie on a single curve. The LM124 response varies with the specific transistor irradiated; similar transient shapes are measured for the different pulse wavelengths, with some deviations in the case of R1. These results reiterate that there is no single, optimum pulsed-laser system for SEE studies; that choice depends on the device to be tested, the intended application of that device, the goals of the test, and availability. For the specific devices evaluated here, any of the four laser systems would be sufficient for most tests.

The front end of the IGISOL facility was upgraded in 2003 by increasing its pumping capacity and by improving the radiation shielding. This marked the birth of IGISOL 3. In late 2005, the traditional conical skimmer electrode of the mass separator was permanently replaced by a radiofrequency sextupole ion beam guide, SPIG, which further improved the mass separator efficiency almost an order of magnitude. The IGISOL 3 facility is described here such as it appeared after all the improvements had been installed.

The proton stopping power of liquid water was, for the first time, measured in the energy range 4.7-15.2 MeV. The proton energies were determined by the time-of-flight transmission technique with the microchannel plate detectors, which were especially developed for timing applications. The results are compared to the literature values (from ICRU Report 49 (1993) and Janni's tabulation (1982 At. Data Nucl. Data Tables 27 147-339)) which are based on Bethe's formula and an agreement is found within the experimental uncertainty of 4.6%. Thus, earlier reported discrepancy between the experimental and literature stopping power values at lower energies was not observed at the energies considered in this experiment.

A Penning trap-based purification process having a resolution of about 1 ppm is reported. In this context, we present for the first time a production method for the most complicated and crucially important nuclear weapons test signature, 133mXe. These pure xenon samples are required by the Comprehensive Nuclear-Test-Ban Treaty Organization to standardize and calibrate the worldwide network of xenon detectors.

The heavy-ion induced electron/hole charge yield in silicon-oxide versus electric field is presented. The heavy-ion charge yield was determined by comparing the voltage shifts of MOSFET transistors irradiated with 10-keV X-rays and several different heavy ions. The obtained charge yield for the heavy ions is in average nearly an order of magnitude lower than for the X-rays for the entire range of measured electric fields.

Radiation tolerance of small-sized CsI (Tl) crystals coupled to silicon photodiodes was studied by using protons. Irradiations up to the fluence of 1012 protons/cm2 were used. Degradation of light output by less than 5% was achieved.

Experimental linear energy transfer values of heavy ions in silicon are presented with comparison to estimations from different semi empirical codes widely used among the community. This paper completes the experimental LET data for the RADEF cocktail ions in silicon.

We report of the radiation hardness measurements that were performed in the developing work of a particle detector on-board ESA's forthcoming BepiColombo spacecraft. Two different high- Z semiconductor compounds, cadmium telluride (CdTe) and mercuric iodide (HgI 2 ), were irradiated with 22 MeV protons in four steps to attain the estimated total dose of 10 12 p / cm 2 for the mission time. The performance of the detectors was studied before and after every irradiation with radioactive 55 Fe source Mn K α 5.9 keV emission line. We studied the impact of the proton beam exposure on detector leakage current, energy resolution and charge collection efficiency (CCE). Also the reconstructive effect of annealing on radiation induced damage was tested for CdTe detector.

Angular and energy distributions of neutrons produced by the interaction of deuterons of 40 MeV in carbon, light- and heavy-water targets, in which they are stopped, have been measured by the activation method. A discrepancy with a time-of-flight measurement for d + C has been found. The results are compared with a Monte-Carlo calculation and are discussed in the frame of building a deuteron-to-neutron converter for the SPIRAL2 radioactive ion-beam facility.

The reference SEU Monitor system designed and presented in 2005 (R. H. SOslashrensen, F.-X. Guerre, and A. Roseng ldquoDesign, testing and calibration of a reference SEU monitor system,rdquo in Proc. RADECS, 2005, pp. B3-1-B3-7) has now been used by many researchers at many radiation test sites and has provided valuable calibration data in support of numerous projects. As some of these findings and results give new insight into improved inter-facility calibrations and provide additional inputs into ongoing SEE research, a few of the more interesting cases are presented. Furthermore the dasiadetector elementpsila, the Atmel AT60142F SRAM, now in a hybrid configuration, will form the key detector element in the Technology Demonstration Module (TDM) to be flown on-board the PROBA-II satellite, to be launched at the beginning of 2009. This flight opportunity extends the Reference SEU Database with both ground and space data, taken on the same device under identical operating conditions. Additionally, the Reference SEU Monitor concept is employed as the basis for the new Reference SEL Monitor system, currently under characterization and preparation for integration on the TDM. Ground SEU/SEL characterization of this latch-up experiment is also presented as well as the basic concept of the TDM, the PROBA-II Radiation Monitor module.

Two man-made wooden objects, called here a “boat” and an “outrigger”, were found above one another in 2004 and 2006 in Kuusamo, Finland. A layer of shore front mud and turf covered them entirely. With partial excavations, samples were taken for age determination and structural studies from both of the items. As measured by the radiocarbon method with a probability of 95.4 %, the items appear to be from periods 5480 – 5300 CalBC and 5025 – 4770 CalBC for the boat and the outrigger, respectively.

In retrospective radon measurements, the 22-y half life of (210)Pb is used as an advantage. (210)Pb is often considered to be relatively immobile in glass after alpha recoil implanted by (222)Rn progenies. The diffusion of (210)Pb could, however, lead to uncertain wrong retrospective radon exposure estimations if (210)Pb is mobile and can escape from glass, or lost as a result of cleaning-induced surface modification. This diffusion was studied by a radiotracer technique, where (209)Pb was used as a tracer in a glass matrix for which the elemental composition is known. Using the ion guide isotope separator on-line technique, the (209)Pb atoms were implanted into the glass with an energy of 39 keV. The diffusion profiles and the diffusion coefficients were determined after annealing at 470-620 degrees C and serial sectioning by ion sputtering. In addition, the effect of surface cleaning on diffusion was tested. From the Arrhenius fit, the activation enthalpy (H) was determined, which is equal to 3.2 +/- 0.2 eV, and also the pre-exponential factor D(0), in the order of 20 m(2)s(-1). This result confirms the assumption that over a time period of 50 y (209)Pb (and (210)Pb) is effectively immobile in the glass. The boundary condition obtained from the measurements had the characteristic of a sink, implying loss of (209)Pb in the topmost surface at high temperatures.

The tendency to reduce the spacecraft mass covers nowadays all components of the spacecraft. One potential target is to reduce the mass of electronics and its housings. The use of composite materials, especially CFRP is a well known and vastly used approach to mass reduction. In cost reduction the use of standard (non-space qualified) electronics has increased. These commercial circuits and other components cannot tolerate as high radiation levels as space qualified components. Therefore the use of standard electronics components poses challenge in terms of the radiation protection capability of the ADPMS housings. The main goal of this study is to give an insight on the radiation shielding protection produced by different configurations of CFRP wolfram laminates of epoxies and cyanate esters and then to compare them to the protection given by the commonly used laminates of aluminium. For a spacecraft operating in LEO and MEO orbits the main components of the space radiation environment are energetic electrons and protons, therefore in our study we will compare the experimental and simulation results of the radiation attenuation of different types of laminates for those particles. At the same time the experimental data has been used to validate the Geant4 model of the laminates, which can be used for future optimizations of the laminate structures.

Researchers performing radiation testing on electronic components often rely on semi-empirical prediction codes for determining the linear energy transfer (LET) (or electronic stopping force) of ions, without paying much attention to their reliability. However, it is seen that estimations calculated with different codes can have over 10% discrepancies, especially in the case of heavy ions with higher LET (e.g., xenon). As a consequence of the modern component fabrication techniques this has become an important issue when studying the radiation durability of electronics. In order to clarify this inconsistency, LET measurements for 131Xe and 82Kr in silicon have been undertaken and obtained results are presented, discussed and compared with earlier predicted data.

Angular and energy distributions of neutrons produced by the interaction of protons of 20, 25 and 40 MeV in 13C targets, in which they are stopped, have been measured by time-of-flight and activation methods. Neutron yields are compared with a Monte-Carlo based model prediction and with the experimental neutron yields of proton and deuteron beams impinging on natural carbon thick targets. The gain with respect to p + 12C is only sizeable at the lowest proton energies. The neutron yield curve of p + 13C versus proton energy is definitely lower than the one of d + 12C, in contrast to the suggestion by an earlier published measurement at 30 MeV.

International audience; Various failure scenarios may occur during irradiation testing of SRAMs, which may generate different characteristic Multiple Cell Upset (MCU) error patterns. This work proposes a method based on spatial and temporal criteria to identify them.

Prompt $ \gamma$ -rays from 191Bi have been studied by means of the recoil-decay-tagging technique. Two superdeformed rotational bands have been observed and interpreted as signature partners originating from the $ 1/2[651]$ Nilsson orbital. This is the lightest Bi isotope where superdeformation has been observed. The two previously observed oblate strongly coupled bands feeding the isomeric $ 13/2^{+}$ state and the $ 9/2^{-}$ ground state were extended to higher spins. The bands built on the $ 1/2^{+}$ intruder state were investigated in detail, showing signs of a more deformed prolate or triaxial shape in 191Bi compared to 193Bi .

In recent years there has been increasing interest in radio-epidemiological techniques to retrospectively measure the radon dose exposure by determining the activity of 210Pb, the longest-lived 222Rn progeny, in glass surface layers. In this study the diffusion of 39 keV 209Pb+ ions implanted into glass using the IGISOL facility has been studied under conditions that mimic the recoil implantation of 210Pb from 222Rn. The resulting depth distributions of 209Pb were then measured after heat treatment in vacuum at different temperatures by a sputter erosion technique. The diffusion coefficient could be described by an Arrhenius equation D = D0exp(−H/kT) where D 0 = 0.30 - 0.24 + 1.14 m 2 s - 1 and H = 2.81 ± 0.11 eV. No statistically significant loss of 209Pb from the sample was observed for annealing between 470 and 600 °C.

An in-beam study of the transfermium nucleus 252No has been performed using the JUROSPHERE II array of germanium detectors coupled to the gas-filled recoil separator RITU. A new technique of recoil-fission tagging was used to extract tagged γ-ray data. Having significant spontaneous fission and α-decay branches, 252No is an ideal candidate for a comparative study. In a similar manner to α-decay tagging the fission events can be used to obtain γ-ray data. The recoil-fission tagged γ-ray spectrum showed a similar structure to the α-decay tagged γ-ray spectrum. By comparing the α-tagged and fission-tagged spectra and decay curves, it was shown that the spontaneous fission originates from the same initial state as the α decay. This extension of the tagging method allows in-beam spectroscopic data to be obtained from heavy nuclei with significant spontaneous-fission branches.

Evidence for the decay of non-yrast states in 254No has been observed for the first time in an experiment performed at the University of Jyvaskyla. The experiment employed the JUROGAM array of germanium detectors coupled to the gas-filled recoil separator RITU and the focal-plane spectrometer GREAT. The ground-state rotational band has been tentatively extended up to a spin of 24ℏ and has a smoothly behaving dynamical moment of inertia. It is speculated that the observation of high-energy γ-rays is due to the decay of a K = 3 band-head state.

The exploitation of the recoil-decay tagging (RDT) technique has reinvigorated experimental investigations of the shape coexistence phenomenon in heavy neutron-deficient nuclei. In a recent experiment using the JUROGAM and GREAT spectrometers in conjunction with the RITU gas-filled separator, excited states have been investigated in the light platinum isotopes. In addition to extending the yrast sequences in 170Pt and 172Pt, the first observation of excited states in the odd-N isotopes, 169Pt and 173Pt, is reported. The bands are discussed in terms of trends in level excitation energies as a function of neutron number.

An experiment has been performed in Jyvaskyla, Finland, using Jurogam in conjunction with RITU and GREAT. This experiment populated several extremely neutron-deficient nuclei around the mass-140 region of the nuclei chart, using the 92Mo(54Fe, α2n) reaction at 245 MeV. Analysis of these data has revealed several previously unobserved isomeric states, in several nuclei. One of these has been assigned to 143Dy with a half-life of 1.2 ± 0.3 µs. The energies of the prompt γ rays in the band built upon the isomer are in agreement with those previously observed.

In recent years, the exploitation of the iecoil-decay tagging (RDT) technique with,large arrays of germanium detectors has revealed much information about the structure of heavy nuclei approaching the proton drip line. The yrast bands of the N

The conversion-electron spectrometer SACRED has been redesigned for use in conjunction with the RITU gas-filled recoil separator. The system allows in-beam recoil-decay-tagging (RDT) measurements of internal conversion electrons. The performance of the system using standard sources and in-beam is described.

Prompt and delayed gamma-ray spectroscopy of very neutron-deficient bismuth isotopes 187, 189Bi has been performed using the recoil decay tagging method. A rotational band has been observed in 189Bi and is interpreted as a complete decoupling of a single proton from the deformed lead core. The results for 187Bi suggest a similar structure and coupling scheme. This study gives the first evidence for a prolate band in a light bismuth nucleus and confirms the prolate character of the low-lying rotational band observed in the core nuclei 188Pb and 186Pb.