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K Lagergren

Publications and source records attributed to K Lagergren.

6 recordsLinked to original sources
PubMed2006

Observation of 54Ni: cross-conjugate symmetry in f7/2 mirror energy differences.

Gamma decays from excited states up to Jpi=6+ in the N=Z-2 nucleus 54Ni have been identified for the first time. Level energies are compared with those of the isobars 54Co and 54Fe and of the cross-conjugate nuclei of mass A=42. The good but puzzling f7/ cross-conjugate symmetry in mirror and triplet energy differences is analyzed. Shell model calculations reproduce the new data but the necessary nuclear charge-dependent phenomenology is not fully explained by modern nucleon-nucleon potentials.

Journal Article↗
PubMed2006

Discovery of 109Xe and 105Te: superallowed alpha decay near doubly magic 100Sn.

Two new alpha emitters 109Xe and 105Te were identified through the observation of the 109Xe --> 105Te --> 101Sn alpha-decay chain. The 109Xe nuclei were produced in the fusion-evaporation reaction 54Fe(58Ni,3n)109Xe and studied using the Recoil Mass Spectrometer at the Holifield Radioactive Ion Beam Facility. Two transitions at Ealpha = 4062 +/- 7 keV and Ealpha = 3918 +/- 9 keV were interpreted as the l = 2 and l = 0 transitions from the 7/2+ ground state in 109Xe (T1/2 = 13 +/- 2 ms) to the 5/2+ ground state and a 7/2+ excited state, located at 150 +/- 13 keV in 105Te. The observation of the subsequent decay of 105Te marks the discovery of the lightest known alpha-decaying nucleus. The measured transition energy Ealpha = 4703 +/- 5 keV and half-life T1/2 = 620 +/- 70 ns were used to determine the reduced alpha-decay width delta2. The ratio delta105Te(2)/delta213Po(2) of approximately 3 indicates a superallowed character of the alpha emission from 105Te.

Journal Article↗
PubMed1976

Visible and non-visible EEG changes demonstrated by spectral parameter analysis.

A change of the heart rate in patients with complete AV-block and externally controllable cardiac pace-makers was earlier shown to influence cerebral function, as measured by psychological tests. To determine whether this influence manifests itself in the EEG, 9 patients aged 43-83 years were examined, all having complete AV-block and externally controllable pace-makers. Their EEGs were recorded at different heart rates between 40 and 100/min at rest and during a mental arithmatic test. The EEG record was evaluated visually and analysed by means of Spectral Parameter Analysis (SPA), introduced by Zetterberg (1969). The changes in the spectral parameters in relation to the heart rates were analysed statistically, In several cases significant changes appeared but the interindividual variations were large. Certain typical patterns could, however, be observed and their importance as a measure of cerebral function due to changes in the cerebral blood flow are discussed. These EEG changes revealed through SPA did not correspond to any visually observable changes in the EEG records. Differences in the spectral parameters between rest and test situations were analysed. Some of the differences found could easily be observed by visual inspection of the EEG. The advantage with SPA was that the changes could be described both qualitatively and quantitavely because SPA separates the spectral properties of the signals into components corresponding to well-known components of the EEG signal.

Adult↗