Ultraviolet-dosis kaarten van Europa ; Een Remote Sensing/GIS toepassing voor onderzoek naar volksgezondheid en milieu

In een proefproject werden remote sensinggegevens van de atmosfeer gebruikt ten behoeve van een studie naar de effecten van veranderingen in de hoeveelheid ultraviolette straling (UV) aan het aardoppervlak en de daaruit resulterende extra risico's voor mens en milieu. Het gepresenteerde model berekent de maandgemiddelde hoeveelheid UV als functie van de ozonkolomdikte, bewolkingsgraad en hoogte boven zeeniveau met hoge ruimtelijke resolutie. De kennis over de verandering in de hoeveelheid UV vormt de basis voor een studie naar veranderingen in risico's van UV blootstelling.In a pilot project remote sensing observations of the atmosphere were used for studying the effects of changing budgets of ultraviolet radiation (UV) on the surface of the earth and the resulting extra risks for humans and the environment. A model is presented to calculate the monthly mean UV budget with high spatial resolution taking thickness of the ozone column, cloudiness and altitude into account. The knowledge on the changes in the UV budget will form the basis of a study to explore the changes in risk related to UV exposure.National User Support Programm

ESCAPE AND SPREADING WIDTHS OF THE ISOBARIC ANALOG STATES OF SN AND TE ISOTOPES

The escape widths for direct proton decay from isobaric analog states in Sb and 1 nuclei have been obtained by combining calculated single-particle widths with experimental spectroscopic information for neutron pickup reactions on the respective Sn and Te target nuclei. They display a pronounced odd-A/even-A staggering effect with very small widths for the even-A isotopes due to the lower proton decay energies. Only data for odd-A nuclei are available, and there is good agreement. Combining the calculated escape widths with the known experimental total widths yields values for the spreading widths. As expected, and in agreement with theoretical predictions, the spreading widths are essentially constant and dependent only weakly on neutron excess. interestingly, the spreading widths are independent of whether statistical isospin-violating neutron decay is energetically possible or not, as is the case for the isobaric analog states of the light Sn isotopes with A <116. The branching ratios for the isospin-forbidden neutron decays from the isobaric analog states average about 95% for the heavier even-A Sb isotopes, and about 60% for the odd-A isotopes. Gamma-ray deexcitation and direct and statistical proton decay compete in the decays of the IAS of the light Sn isotopes, and a branching ratio of about 90% for gamma-ray deexcitation is expected for the IAS in 112Sb

Effectieve UV-straling in Nederland

In dit rapport worden de meetresultaten en eerste analyses van de spectrale UV-metingen gepresenteerd, zoals die zijn verkregen met de bij het RIVM ontwikkelde spectrale UV-meetsysteem, dat sedert april 1993 operationeel is. De spectrale meetgegevens zijn in dit rapport geanalyseerd met betrekking tot effecten van variaties van de dikte van de ozonlaag, bewolking en aerosolen. Metingen zijn vergeleken met modelberekeningen van de UV-transfer voor onbewolkte situaties en een empirische methode is ontwikkeld en toegepast voor de analyse van de invloeden van bewolking en aerosolen. Bewolking en aerosolen reduceren de effectieve UV jaardosis met circa 35%. De methoden zijn gebruikt voor het berekenen van de effectieve UV jaardoses in de periode van 1991-1994. De resultaten zijn vergeleken met een referentie jaarsom, gebaseerd op gemiddelde ozonwaarden in de periode van 1972-1993 en een gemiddelde reductie door bewolking en aerosolen. Vergeleken met de referentie jaarsom is de voor bewolking en aerosolen gecorrigeerde berekende jaardosis in 1991 3% lager, de jaardosis in 1992 5% hoger en in 1993 12% hoger. De voor bewolking en aerosolen gecorrigeerde jaardosis in 1994 was ruim 8% hoger dan de referentie jaarsom, hetgeen inhoudt dat de sterke opwaartse trend van 1992 en 1993, die mogelijk is beinvloed door de vulkaanuitbarsting van de Pinatubo in 1991, niet wordt voortgezet. Niettemin is de jaardosis in 1994 beduidend hoger dan de jaardosis in 1991 en de referentie dosis.This report presents the observations and first analysis of the spectral and effective UV-irradiance levels in the Netherlands (at 52o N) obtained with the UV-monitoring system developed at RIVM and operational since April 1993. The spectral data have been analysed with respect to effects of variations of thickness of the ozone layer, cloud cover and aerosols. Measurements were compared with UV-transfer model calculations for cloudless situations. An empirical method is developed and applied for the evaluation of cloud and aerosol effects on atmospheric UV-transfer. Clouds and aerosols were found to reduce the yearly effective UV dose by 35% compared to clear sky estimates. The method is used to analyse yearly effective UV doses in the Netherlands in the period 1991-1994. The results are compared to a reference yearly UV dose, based on average ozone values over 1972-1993, and average cloud and aerosol reductions. Compared to the reference yearly dose the cloud and aerosol corrected yearly doses in 1991 were 3% lower, the doses in 1992 5% higher, and in 1993 12% higher. The cloud and aerosol corrected yearly dose for 1994 was 8% higher than the reference yeardose. Thus the sharp upward trend observed in 1992 and 1993, which might have been influenced by the volcanic eruption of the Pinatubo in 1991, has not been continued. Nevertheless, the 1994 estimates are consistently higher than the 1991 values and the reference dose.DGM/SVS/SN

PHOTONS IN THE PROTON-INDUCED REACTION WITH IN AT E(P)=50-MEV

Photon emission in proton-induced reactions at 50 MeV with In-115 was studied. Analyses of the measured photon spectrum show that the GDR couples to the compound states as well as to pre-equilibrium states. The centroid and width of the GDR strength function were determined as E(GDR) = 15.4 +/- 0.7 MeV and GAMMA(GDR) = 6.2 +/- 0.5 MeV. From the measured gamma-ray yield above E(gamma) = 30 MeV, a value of (7.1 +/- 1.4) x 10(-5) for the hard-photon emission probability per single proton-neutron collision is inferred

Excitation of the isovector GDR by inelastic α-scattering as a measure of the neutron skin of nuclei

The cross section of the isovector giant dipole resonance (GDR) has been measured in the Sn-116, Sn-124(alpha, alpha'gamma0), 150Nd(alpha, alpha'gamma0) and Pb-208(alpha, alpha'gamma0) reactions at E(alpha) = 120 MeV and 0-degrees less-than-or-equal-to THETA(alpha') less-than-or-equal-to 3-degrees. The results are compared with DWBA calculations performed with nuclear GDR form factors that depend on the relative difference between the radii of proton and neutron distributions (DELTAR(PN)/R0). Taking a linear combination of form factors provided by the Gold-haber-Teller and Steinwedel-Jensen models in a ratio that fits the GDR systematics, the DELTAR(PN) Values for Sn-116, 124Sn and Pb-208 were deduced by comparing measured and calculated cross sections to be 0.02 +/- 0.12 fm, 0.21 +/- 0. 11 fm, and 0. 19 +/- 0.09 fm, respectively. For the deformed 150Nd, the neutron-skin thickness along and perpendicular to the symmetry axis was found to be 0.22 +/- 0.16 and 0.50 +/- 0.15 fm, respectively, yielding beta2n/beta2p = 0.92 +/- 0.08