Double electron capture in 156Dy, 162Er and 168Yb

The double electron capture half-lives of 156Dy, 162Er and 168Yb are evaluated using the pseudo SU(3) model, which describes ground and excited bands as well as their B(E2) and B(M1) transition strengths in remarkable agreement with experiment. The best candidate for experimental detection is the decay 156Dy -> 156Gd, with tau{1/2} (0+{gs} --> 0+{gs}) = 2.74 E22 yrs and tau{1/2} (0+{gs} --> 0+{1}) = 8.31 E24 yrs.Comment: 7 pages, 1 figure. Physics Letters B, in pres

Investigation of Polar Mesosphere Summer Echoes in Northern Scandinavia

This PhD thesis deals with phenomena which are closely related to the unique thermal structure of the polar summer mesosphere, namely Polar Mesosphere Summer Echoes (PMSE). PMSE are strong radar echoes commonly observed by VHF MST radars from thin layers in the 80-90 km altitude interval at high latitudes during summer. They follow a seasonal pattern of abrupt appearance in late May and a gradual disappearance in mid-August. This period corresponds roughly to the time between the completion of the summer time cooling of the polar mesopause to the time of reversal of the mesospheric circulation to autumn condition. In this connection, PMSE are associated with the extremely low temperatures, i.e. below 140 K, which are unique to the polar summer mesopause. Traditional theories of radar (partial) reflection and scattering have been unable to explain the PMSE and the exact mechanism for their occurrence remains unclear despite the steadily increasing interest in them over the past 20 years. Currently accepted theories regarding the mechanism giving rise to PMSE agree that one of the conditions needed for enhanced radar echoes is the presence of low-mobility charge carries such as large cluster ions and ice aerosols which capture the ambient electrons. It has been established that the PMSE are in some way associated with noctilucent clouds (NLC), layers of ice crystals, which constitute the highest observed clouds in the earth’s atmosphere. PMSE occurrence and dynamics are also found to be closely connected with the planetary and gravity waves. Observations of PMSE presented in this thesis have been carried out by the Esrange MST radar (ESRAD) located at Esrange (67°56’N, 21°04’E) just outside Kiruna in northernmost Sweden. The radar operates at 52 MHz with 72 kW peak power and a maximum duty cycle of 5%. The antenna consists of 12x12 array of 5-element Yagis with a 0.7l spacing. During the PMSE measurements the radar used a 16-bit complementary code having a baud length of 1mS. This corresponds to height resolution of 150 m. The sampling frequency was set at 1450 Hz. The covered height range was 80-90 km. The presence of PMSE was determined on the basis of the radar SNR (signal-to-noise ratio). The PMSE measurements have been made during May-August each year since 1997. PMSE seasonal and diurnal occurrence rates as well as dynamics have been studied in connection with tidal winds, planetary waves, temperature and water vapor content in the mesosphere (Papers I, IV and VI). Simultaneous and common-volume observations of PMSE and noctilucent clouds have been performed by radar, lidar and CCD camera (Paper V). Correlation between variations in PMSE and variations in extra ionization added by precipitating energetic electrons or high-energy particles from the Sun has been examined (Papers II and III). Possible influence of transport effects due to the electric field on PMSE appearance has been studied during a solar proton event (Paper III)

The APTAS student CubeSat Mission: A case study for reflective practitioner in education and student teams

Despite the growing number of educational CubeSat projects, there is a lack of available literature related to analysis of good practices and lessons learned associated with learning environment of such university student projects, their internal organisational, and management issues. Difficulties arise when international standards, procedures and practices from professional satellite development projects must be adopted by student teams to their local projects. This paper discusses educational, organisational, and human factors that contribute to the success of the master student space projects at Luleå University of Technology, Kiruna Space Campus. The authors focus on project structure, management, working, and learning environment of the ongoing student CubeSat project APTAS and analyse problems and difficulties encountered in relation to the other actual student space projects at LTU. The result of quantitative and qualitative analysis of questionnaires, interviews, reflections and observations of the national and international master students is presented, and provides practical advice for university student teams and their supervisors.Validerad;2023;Nivå 2;2023-08-07 (hanlid)</p

Development of a Competence Ecosystem for the Future Space Workforce: Strategies, Practices and Recommendations from International Masterprograms in Northern Sweden

Requirements from the global labor market have substantially changed in recent years. Graduate and post-graduate students with excellent subject knowledge, deep understanding of modern working methods, technicaland higher-order thinking, engineering intuition and problem-solving skills are in great demand. They should also have professional skills such as well-developed abilities in communication and teamwork, usually in an international work environment. This review discusses the advantages of multidisciplinary study environment, educational strategies such as student-oriented teaching, project-based learning with its applicability to a“real-world” setting, active learning techniques, development of entrepreneurial skills, lessons learned and best practices from the international Master Program in Spacecraft Design and the Joint Master Program in SpaceScience and Technology – SpaceMaster at Luleå University of Technology in northern Sweden. The importance of complementarity between formal, informal and non-formal learning methods for science and engineering studentshas been specifically highlighted. Connections to the world of work, through active industry involvementin the education in a systematic way, e.g. External Advisory Board, shared services and facilities, joint projectsand supervision of Master and PhD students, is recognised as a key success factor for professional training. A structural combination of modern pedagogical tools, strategic partnership with industry, business entities, academic partners and up-to-date multidisciplinary labs creates the conceptual framework for a CompetenceEcosystem for fostering a new generation of space scientists and engineers.Validerad;2022;Nivå 2;2022-06-16 (hanlid)</p

Development of a competence ecosystem for the future space workforce: strategies, practices and recommendations from international master programs in northern Sweden

Requirements from the global labor market have substantially changed in recent years. Graduate and post-graduate students with excellent subject knowledge, deep understanding of modern working methods, technicaland higher-order thinking, engineering intuition and problem-solving skills are in great demand. They should also have professional skills such as well-developed abilities in communication and teamwork, usually in an international work environment. This review discusses the advantages of multidisciplinary study environment, educational strategies such as student-oriented teaching, project-based learning with its applicability to a“real-world” setting, active learning techniques, development of entrepreneurial skills, lessons learned and best practices from the international Master Program in Spacecraft Design and the Joint Master Program in SpaceScience and Technology – SpaceMaster at Luleå University of Technology in northern Sweden. The importance of complementarity between formal, informal and non-formal learning methods for science and engineering studentshas been specifically highlighted. Connections to the world of work, through active industry involvementin the education in a systematic way, e.g. External Advisory Board, shared services and facilities, joint projectsand supervision of Master and PhD students, is recognised as a key success factor for professional training. A structural combination of modern pedagogical tools, strategic partnership with industry, business entities, academic partners and up-to-date multidisciplinary labs creates the conceptual framework for a CompetenceEcosystem for fostering a new generation of space scientists and engineers.Validerad;2022;Nivå 2;2022-06-16 (hanlid)</p

Large-Scale Sea Ice Divergence and Convergence Monitoring in the Arctic Ocean during Spring 2018

This study investigates sea ice motion in the Arctic Ocean during the year 2018 to detect areas of ice deformation. We aim to improve the current understanding of large-scale sea ice circulation by examining ice convergence/divergence during the early melt-season. OSISAF sea ice drift data provided by EUMETSAT were used for the analysis during the months of March and April. Daily ice drifting speed and deformation parameters showed a strong correlation throughout the observed interval, while a local-scale analysis revealed different patterns for ice divergence and convergence in areas of enhanced ice drift.Finansiär: Arctic Challenge for Sustainability (ArCS)</p

ESRAD observations of lee waves and associated atmospheric structures

International audienc

1997: MST radar observations of lee waves in the Kiruna area: A complement to optical measurements of polar stratospheric clouds

International audienc

Wind profiling with ESRAD, the Esrange radar

International audienc

Polar Mesosphere Winter Echoes and their relation to infrasound

Polar Mesosphere Winter Echoes (PMWE) are radar echoes that originate from the mesosphere at 50-80 km altitude and are observed with VHF radars during equinox and winter seasons. Strong PMWE are relatively rare phenomena, in most cases they are observed when the lower ionosphere displays high ionisation. Interpretations of observational results concerning PMWE are controversial and the origin of the echoes is still under debate. Especially intriguing is that in some cases of strong PMWE, the measured horizontal speeds of the radar reflecting structures can exceed 300 m/s. Radar reflection (scattering) by infrasound waves at frequencies below about 2 Hz was suggested in order to explain these observations. We will give recent examples of PMWE events of high horizontal speed as observed with the 52 MHz MST radar (ESRAD) located at Esrange (68°N, 21ºE) in northern Sweden. Together with this we will analyse infrasound measurements made at ground-based stations near Kiruna (67.5°N, 20.13ºE) and at the infrasound station IS37 (69°N, 18ºE) in Norway during these events. We discuss prospective relations between PMWE and the microbaroms that are generated by ocean swell in the North Atlantic