271 research outputs found
Enhancing the energy resolution of resonant coherent excitation using the cooled U 89+ beam extracted from the ESR
Synopsis We report on the resonant coherent excitation (RCE) of the 2 s -2 p 3/2 transition in Li-like U 89+ with an enhanced energy resolution, which was achieved by reducing the projectiles momentum spread. The kinetic temperature of the beam was decreased by electron cooling in the ESR, and the collisional momentum broadening in the target was suppressed by the use of thin crystal (1.0 and 2.5 μm-thick). The resonance width was observed to be ∼1.4 eV in FWHM, which is three-times narrower than that from the previous work
Electron gas polarization effect induced by heavy H-like ions of moderate velocities channeled in a silicon crystal
We report on the observation of a strong perturbation of the electron gas
induced by 20 MeV/u U ions and 13 MeV/u Pb ions channeled in
silicon crystals. This collective response (wake effect) in-duces a shift of
the continuum energy level by more than 100 eV, which is observed by means of
Radiative Electron Capture into the K and L-shells of the projectiles. We also
observe an increase of the REC probability by 20-50% relative to the
probability in a non-perturbed electron gas. The energy shift is in agreement
with calculations using the linear response theory, whereas the local electron
density enhancement is much smaller than predicted by the same model. This
shows that, for the small values of the adiabaticity parameter achieved in our
experiments, the density fluctuations are not strongly localized at the
vicinity of the heavy ions
A 560 yr summer temperature reconstruction for the Western Mediterranean basin based on stable carbon isotopes from <i>Pinus nigra</i> ssp. <i>laricio</i> (Corsica/France)
The Mediterranean is considered as an area which will be affected strongly by current climate change. However, temperature records for the past centuries which can contribute to a better understanding of future climate changes are still sparse for this region. Carbon isotope chronologies from tree-rings often mirror temperature history but their application as climate proxies is difficult due to the influence of the anthropogenic change in atmospheric CO<sub>2</sub> on the carbon isotope fractionation during photosynthetic CO<sub>2</sub> uptake. We tested the influence of different correction models accounting for plant response to increased atmospheric CO<sub>2</sub> on four annually resolved long-term carbon isotope records (between 400 and 800 yr) derived from Corsican pine trees (<i>Pinus nigra</i> ssp. <i>laricio</i>) growing at ecologically varying mountain sites on the island of Corsica. The different correction factors have only a minor influence on the main climate signals and resulting temperature reconstructions. Carbon isotope series show strong correlations with summer temperature and precipitation. A summer temperature reconstruction (1448–2007 AD) reveals that the Little Ice Age was characterised by low, but not extremely low temperatures on Corsica. Temperatures have been to modern temperatures at around 1500 AD. The reconstruction reveals warm summers during 1480–1520 and 1950–2007 AD and cool summers during 1580–1620 and 1820–1890 AD
SPARC Collaboration: New Strategy for Storage Ring Physics at FAIR
SPARC collaboration at FAIR pursues the worldwide unique research program by
utilizing storage ring and trapping facilities for highly-charged heavy ions.
The main focus is laid on the exploration of the physics at strong, ultra-short
electromagnetic fields including the fundamental interactions between electrons
and heavy nuclei as well as on the experiments at the border between nuclear
and atomic physics. Very recently SPARC worked out a realization scheme for
experiments with highly-charged heavy-ions at relativistic energies in the
High-Energy Storage Ring HESR and at very low-energies at the CRYRING coupled
to the present ESR. Both facilities provide unprecedented physics opportunities
already at the very early stage of FAIR operation. The installation of CRYRING,
dedicated Low-energy Storage Ring (LSR) for FLAIR, may even enable a much
earlier realisation of the physics program of FLAIR with slow anti-protons.Comment: IX International Workshop on "APPLICATION OF LASERS AND STORAGE
DEVICES IN ATOMIC NUCLEI RESEARCH", Recent Achievements and Future Prospects,
May 13 - 16, 2013, Pozna\'n, Polan
Дендрокліматологічні дослідження сосни звичайної в насадженні Лівобережного лісостепу України
Purpose of this research was to detect influence of climatic change on pine radial increment in stand in the Left-bank Forest-steppe of Ukraine as example 100-years-old stand at State Enterprise 'Kharkiv forest scientific research station’. Methods. Dendrochronological. Method of correlation function and multiple regressions (response function) were used to analyze the influence of climatic factors on tree radial increment. For this purpose computer program RESPO was used. Results. Tree ring series were built and were used for correlation analysis between climatic factors and pine radial increment for two periods: 1960-1988 and 1988-2016.Years of minimum (1933, 1942, 1956, 1972, 1976, 1976, 1987, 1992, 2002, 2006 та 2012) and maximum (1933, 1942, 1956, 1972, 1975, 1976, 1979, 1979, 1979, 1987, 1992, 2002 та 2012) of radial increment were detected. Depressions of pine radial increment were as a result of negative weather conditions: low and high winter and early-spring temperature, droughts during vegetation period. Maximums of radial increments were depended on favorable weather conditions for pine radial growth. Correlation and Response analysis for two periods showed that increase of temperature and precipitation, excluding winter precipitation, changed response of forest ecosystems to climatic change: if in first period (1960-1988) radial increment limited by April temperature and together July temperature positively influenced on radial growth, in second period (1988-2016) June temperature negatively infuenced on radial increment. Slight increase precipitation during vegetation period could not soften impact if high temperature during vegetatation period on tree radial increment. Conclusions. At comparison 1960-1988 and 1988-2016 it was detected that during first period positive influence of summer temperature on radial growth was distinctive and for second period one started to limit increment (negative influence) were detected. Slight increase of precipitation for vegetation period in second period significantly didn’t influence on pine radial growth. In second period increase of winter temperature and number of thaws negatively influenced on soil moisture, decreased of tree ring widths.Цель. Выявление влияния изменений климата на радиальный прирост сосны в Левобережной степи Украины на примере 100-летнего соснового насаждения ГП «Харьковская лесная научно-исследовательская станция». Методы. Дендрохронологические. Результаты. Созданы древесно-кольцевые хронологии для установления связей между климатическими показателями и радиальным приростом сосны за два периода: 1960-1988 та 1988-2016 гг. Корреляционный анализ и функция отклика за два периода показали, что при увеличении температур и количества осадков (исключением стали зимние осадки) изменилась реакция лесных екосистем на вариации условий природной среды. Так, если в первом периоде (1960-1988 гг.) радиальный прирост ограничивали апрельские температуры, в то же время на прирост положительно влияли летние (июльские) температуры, то во втором периоде летние температуры (июнькие) стали негативно влиять на прирост деревьев. Незначительное увеличение количества осадков за вегетационный период не смогло смягчить влияние высоких температур вегетационного периода на радиальный прирост. Выводы. При сравнении 1960-1988 и 1988-2016 гг. выявлено, что для первого периода характерно положительное влияние летних температур на радиальный прирост, однако для второго периода они начинают ограничивать прирост деревьев. Незначительное увеличение количества осадков за вегетационный период не смогло смягчить влияние высоких температур вегетационного периода на радиальный прирост.Мета. Виявлення впливу змін клімату на радіальний приріст сосни в Лівобережному степу на прикладі 100-річного соснового насадження ДП «Харківська лісова науково-дослідна станція». Методи. Дендрохронологічні. Результати. Створено деревно-кільцеві хронології, які використано у встановленні зв’язків між кліматичними чинниками та радіальним приростом сосни за два періоди: 1960-1988 та 1988-2016 рр. Кореляційний аналіз та функція відгуку за два періоди показали, що при збільшенні температур та кількості опадів (виняток – зимові опади) змінилася реакція лісових екосистем на зміни клімату: так, якщо в першому періоді (1960-1988 рр.) радіальний приріст обмежували квітневі температури, водночас позитивно впливали липневі температури, то у другому періоді (1988-2016 рр.) червневі температури вже негативно впливали на приріст. Незначне збільшення кількості опадів за вегетаційний період не змогли пом’якшити вплив високих температур вегетаційного періоду на радіальний приріст. Висновки. При порівнянні 1960-1988 та 1988-2016 рр. виявлено, що якщо для першого періоду характерний позитивний вплив літніх температур на радіальний приріст, то для другого періоду вони починають обмежувати приріст. Незначне збільшення кількості опадів за вегетаційний період у другому періоді не змогло пом’якшити вплив високих температур на радіальний приріст дерев.
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