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In a preliminary study, in vivo skull measurements and in vitro urine measurements of 210 Pb and nat U have been performed to find out the individual, chronic exposure to waterborne natural radionuclides of a small group of Finnish people. For their domestic water, the studied individuals use water from drilled wells containing elevated concentrations of natural uranium and its daughter nuclides ( 234,235,238 U, 222 Rn, 226,228 Ra, 210 Po, 210 Pb). Enhanced 210 Pb and 235 U activities were observed in several people. A positive correlation is observed between the U concentration in urine (μg d -1 ) and the number of counts (cpm) in the gamma ray energy peaks originating from the decay of 235 U and 234 Th respectively. Calibration of the detector setup and the determination of background sources are in progress.

In vivo skull measurements of Pb-210 have been performed to assess the individual, chronic intakes of natural radionuclides of five members of a family (two adults and three descendants), living in Turku, Finland. The family derives its household water from a drilled well since 16 years. The well water contains high amounts of Rn-222 and other radionuclides of the U-238 decay chain. The cumulative uptake of Pb-210 into the body was assessed for each single person by using the biokinetic model of ICRP 67, taking into account the results of water measurements. A fairly good agreement between model and measurement was achieved for all persons of the family, with exception of the father, who showed a skull activity, which is a factor of 10 lower than expected. It is assumed that he is drinking much less well water, as he stated in a personal interview, but this assumption could not be confirmed with absolute confidence.

In vivo skull measurements of 210Pb have been performed to assess the individual, chronic exposures of two persons living for 28 years in a house with a distinctly enhanced radon concentration of more than 10,000 Bq/m3. A partial body counter consisting of 4 HPGe detectors, which were placed close to parietal positions of the head, was used in the study. The lower limit of detection of 210Pb activity in the skeleton was found to be 40 Bq. Lead-210 activities of up to 152 Bq were found in the test persons, whereas no activity could be measured in an unexposed control person. The cumulative uptake of 210Pb into the body was assessed for each single test person by using the ICRP respiratory tract and the biokinetic models. A fairly good agreement (within a factor of 2) between in vivo measurements and model was achieved for these two test persons. The technique used in the study may be a useful tool to evaluate assumptions, which have to be made for the reconstruction of individual, cumulative exposures to high radon concentrations.

An individual in vivo monitor using seven Germanium detectors with a total area of 24,000 mm2 was prepared for 210Pb skull measurements. System calibration with anthropomorphic head phantoms and a straightforward efficiency estimation yielded a minimum detectable activity (MDA) of 6.7 Bq and a lower limit of detection (LLD) of 14 Bq (CL: 95%). Two selected persons were measured for 1 h each to reconstruct their cumulative radon exposure. From the added pulse height spectrum a 210Pb activity in the skull of 3.1±7.2 Bq (result with 95%-CL) was estimated, but clear conclusions on their radon exposure using a new metabolism model of lead in man could not be drawn. Further improvements in the selection of highly exposed persons as well as head calibration and Lackground reduction are necessary using this attempt for retrospective exposure reconstruction.

Cumulative and independent fission product yields of the reaction197Au(d,f) were determined at a beam energy of 80 MeV at the Julich isochronous cyclotron. Off-beamγ-ray measurements applying a catcher foil technique and chemical separation, and in inbeam kinetic energy measurements of fission products were performed. The complete yield distribution of post neutron emission fission fragments is represented by a single function, consisting of the product of two Gaussians. The mass distribution is characterized by the widthσ A =12.5amu. The width of theZ-distribution for eachA-chain is given byσ Z =0.63amu.

Mossbauer absorption experiments on 57 Fe of deoxygenated myoglobin crystals and on K 4 57 Fe(CN) 6 dissolved in the water of metmyoglobin crystals were performed over a large temperature range. At low temperatures the mean square displacements, 〈 x 2 〉, of the iron indicate solid-like behaviour of the whole system, whereas at higher temperatures protein-specific modes of motion contribute to 〈 x 2 >. The protein dynamics are correlated with the mobility of the water within the protein crystals. A Brownian oscillator is used to model the protein-specific modes of motion measured at the 57 Fe nucleus. Three modes are necessary for understanding the Mossbauer spectrum. Two of them correspond to an extremely overdamped Brownian oscillator. The third mode can be understood as quasi-free diffusion. Whereas the protein molecule is frozen in conformational substates in the low temperature regime, it reaches transition states with a finite probability in the high temperature regime. The surface water mediates a possible trigger mechanism that switches on protein dynamics within a narrow temperature interval. Results from Mossbauer spectroscopy and from X-ray structure analysis are compared.

From Mossbauer spectra of the 36.2keV and 69.5keV gamma rays of189Os, isomer shifts and electric quadrupole interactions for a number of chemical compounds of osmium in the oxidation states +8, +6, +4, +3, and +2 were obtained. The results show that the dependence of the isomer shifts on the oxidation state of Os follows the general pattern established for other transition elements like Ru and Ir. A comparison of the isomer shift data with electron densities at the Os nuclei resulting from relativistic self-consistentfield calculations for free Os ions yieldsΔ 〈r2〉 [36 keV]=−2.0 · 10−3 fm2 andΔ 〈r2〉 [69 keV]=−0.13 · 10−3 fm3 for the changes of the mean-square nuclear charge radius of189Os. These values are in qualitative agreement with an interpretation of the low-energy level scheme of189Os in terms of two rotational bands.

Mossbauer transmission experiments with the 137, 155, 69 and 187 keV gamma rays of186, 188, 189, 190Os, respectively, yielded the electric quadrupole splitting of these gamma resonance lines in OsO2 and OsP2. From the results the following ratios of quadrupole moments were derived:Q2+(186Os, 137 keV):Q2+(188Os, 155keV):Q2+(190Os, 187 keV):Q3/2−(189Os, g.s.)=(+1.100±0.020): 1.0:(+0.863±0.051): (−0.586±0.011) andQ5/2−(189Os, 69 keV)/Q3/2−(189Os, g.s.)=−0.735 ±0.012. The ratios for180, 188, 190Os are, within their limits of error, in agreement with the expectation of the rotational model, indicating that the pairing-plusquadrupole model calculations of Kumar and Baranger predict too rapid a transition form rotational to vibrational nuclei. Applying this argument to186Os in particular and using the measured ratios, one obtains a set of values for the quadrupole moments themselves, namelyQ2+ (186Os)=−(1.50 ± 0.10)b,Q2+(188Os)=−(1.36± 0.09) b,Q2+ (190Os)=−(1.18 ± 0.08) b,Q3/2−(189Os)=+ (0.80 ± 0.06) b, andQ5/2− (189Os)=− (0.59 ± 0.05) b. For the electric field gradient at Os nuclei in Re metal a value ofVzz=−(3.3 ± 0.6) · 1017 V/cm2 was found. A measurement with a magnetically split source yielded δ=+ 0.685 ± 0.025 for theE2/M1 mixing parameter of the 69 keV transition of189Os,g5/2−/g3/2−=0.895 ± 0.006 for the ratio of theg-factors of the 69 keV state and the groundstate, andHi=−(1135 ± 20) kOe for the hyperfine field at Os nuclei in an iron matrix.

The spectroscopic quadrupole moments and the magnetic dipole moments of the lowest 2+ states in186Os (137 keV) and188Os (155 keV) have been determined by Mosbauer transmission experiments. The electric quadrupole momentsQ2+(Os 186)=− (1.80±0.22) b andQ2+(Os 188)=−(1.81±0.24) b as well as their ratioQ2+(Os 188)/Q2+(Os 186)=1.00±0.07 within the limits of error agree withB(E2) data, if a comparison on the basis of the rotational model is made. For the g-factors and their ratio g2+(Os 186)=0.281±0.008, g2+(Os 188)=0.305±0.015 andg2+(Os 188)/g2+(Os 186)=1.08±0.05 was obtained. All results are compared with recent model calculations.

The 69.6-keV level with spin 5/2− in189Os was investigated by the recoilless resonance absorption technique. Its magnetic moment was found to beμ (5/2)=(0.977±0.014)μN. From the measured ratio of the excited and ground-state electric quadrupole moments,Q(5/2)/Q(3/2)=−0.79±0.09, the excited-state quadrupole momentQ(5/2)=−(0.72±0.11)b could be derived. TheE2/M1 mixing parameter of the 69.6-keV ground-state transition was found to beδ=+0.69±0.10. The results are interpreted in terms of two low-energy rotational bands with strong Coriolis mixing.

Mössbauer spectra of human deoxyhemoglobin and hemochrome frozen solutions, selectively enriched with 57Fe in either the alpha chains or the beta chains, were measured from 4.2 to 250 K. The Lamb-Mössbauer factor, ln f = 4II2 [x2]gamma/lambda 2, was calculated from these spectra and gives the structural dynamics of the iron atom (heme). Large differences in the mean-squared displacement, [x2]gamma, of the heme between hemochrome and deoxyhemoglobin at temperatures above 210 K were observed, demonstrating that when iron is bound to a rigid part of the protein (i.e., distal histidine in hemochrome), motions of the heme are suppressed (i.e., the dynamics are decreased). Comparison of the motions of these two hemoglobins proves that molecular diffusion can be neglected in an analysis of the dynamics below approximately 250 K.

Measurements of Mossbauer isomer shifts of the 36.2 keV and 69.6 keV γ -rays of 189 Os in OsO 4 , K 4 Os(CN) 6 and K 2 OsCl 6 yield δ 〈 r 2 〉 [36.2 keV]/ δ 〈 r 2 〉 [69.6 keV] = 16.6 ± 1.3, which supports the notion of Coriolis-coupled rotational bands in 189 Os.