Sergio P Ratti

2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) persistence in the Seveso (Milan, Italy) soil.

Preliminary results of a new study on TCDD environmental persistence at Seveso (Milan, Italy) are presented. For this study, the most contaminated territory, Zone A, was divided into areas to fractionate the available TCDD levels in soil into data sets with reduced value spreads. In addition, various time subsets were defined for each area. Selected data were fitted with the exponential model y = y0.e-k.1. It was estimated that at least 1.2 kg TCDD was present in Zone A shortly after the accident. On average, a considerable portion (23%) of this amount lay on vegetation; TCDD which was not photodegraded or volatilized before the heavy rains of fall 1976, was later washed off and transferred to ground by water action. From this study, mean analytical underestimations affecting January 1977 and March 1978 contamination map data were on the order of 30 and 24%. All the above figures are considered optimistic. A few years after the accident, mean TCDD half-life in soil appeared to be 9.1y (t1/2-95% CLs, 6.2-17y).

Recovery yields of early analytical procedures to detect 2,3,7,8-tetrachloro-dibenzo-p-dioxin (TCDD) in soil samples at Seveso, Italy

Abstract Tetrachlorodibenzo-p-dioxin (TCDD) levels and distribution in soil over a vast area at Seveso (Milan, Italy) have been investigated several times since accidental release of the chemical at the Givaudan-Hoffman-La Roche Plant on July 10, 1976. Analytical factors markedly biased the data obtained from 1976 to 1978. Hence, this paper examines and estimates the systematic analytical errors in early TCDD determinations with a specific focus on soil assay. The absolute mean analytical recovery from late 1979 onward is used as a reference (yield, 75–80%). No TCDD loss is assumed to have occurred over time. Under these assumptions, relative mean recoveries for January 1977 and March 1978 map data are shown to be as low as

Fractal and multifractal approach to environmental pollution

A few case studies will be presented involving both radioactive and chemical pollution at small, medium, and large space-time scales. Reported are recent advances in the field of environmental pollution involving the use of fractals and multifractals. The mathematical tools proposed here may offer new perspectives for investigating many of the problems of nonlinear variability which commonly arise when dealing with pollutants, such as the presence of outliers and the sparseness of the sampling networks. They may also lead to a simplification of the models adopted for studying natural phenomena, thanks to a scaling approach. Finally, they may provide parameters whose values are directly related to the nonlinear dynamics involved in the pollutant distribution in the environment which, in turn, may be relevant for computer simulation and epidemiological or risk assessment purposes.

Multifractal objective analysis of seveso ground pollution

We analyse the Dioxin (TCDD) pollution of the Seveso (Milan, Italy) territory, seeking to statistically parametrize it in terms of Universal Multifractals. The data set contains the measurements collected from 1976 up to 1981. We apply the Double Trace Moment (DTM) technique in order to estimate both α (the degree of multifractality) and C 1 (the codimension of the mean field) and (with the help of spectral analysis) we also calculate H (the degree of non‐conservation of the process). We then discuss the effects introduced by statistical undersampling and network sparseness and provide a way to statistically correct for these effects. We conclude that the ground distribution of Dioxin shows clear multifractal features and can be classified as an unconditionally hard universal multifractal process.

Universal multifractal approach to intermittency in high energy physics

A new stochastic approach to intermittency in high energy physics is proposed. It yields to intermittency exponents defined independently of phase-space dimensions; their role in the calculation of generalized moments is discussed. A straightforward application of universal multifractals is suggested and a new parametric technique for phase-space analysis is provided.

NEUTRON-INDUCED SINGLE EVENT UPSET ON THE RPC FRONT-END CHIPS FOR THE CMS EXPERIMENT

Neutrons from a reactor and from a cyclotron have been used to characterise the CMS Resistive Plate Chambers (RPCs) front-end chip to neutron-induced damaging events. Single Event Upset (SEU) cross-sections have been measured up to for different chip thresholds. Tests at a reactor were done with an integrated fast () neutron fluence of and a thermal neutron fluence of . High-energy neutrons from a cyclotron were used up to a fluence of . Data indicate the existence of a chip SEU sensitivity already at thermal energy and a saturated SEU cross-section from 3 to . Values of the SEU cross-sections from the thermal run well agree with those obtained by another CMS group that uses the same technology ( BiCMOS) though with different architecture. Cross-sections obtained with fast neutrons (from to about ) are consistently higher by one order of magnitude compared to the thermal one. The average time between consecutive SEU events in each chip of the CMS barrel RPCs can be estimated to be 1 h.

Light Quark Photoproduction at Fermilab

This analysis is based on approximately 900,000 quasi-exclusive π+ π- pairs recorded with the E687 spectrometer during the 1990/91 fixed target runs [1] at high energy (7.5 < \(\sqrt s\) < 17.0). Exclusive final states are selected based on the total number of charged tracks seen in the spectrometer and by requiring no visible energy in our electromagnetic calorimeters. Most of the data (≈98%) has been taken with a Beryllium target (a small part of the date were taken with A1 and Pb targets to prove that our samples are indeed diffractive by relating the highest t-slope to the size of the nucleus).

Behaviour of semi-inclusive sphericity distributions and a two-component uncorrelated cascade model

A simple two component uncorrelated cascade model is proposed which reproduces the semi-inclusive Sphericity distributions observed in lowpT hadron-hadron collisions. It is pointed out that if α is an exponential parameter inserted into the quark-quark structure function, theS dependence of the semi-inclusive sphericity distribution for multiplicityn goes as exp (−α/nS). This conclusion agrees extremely well with the experimental data.

Misure di insiemi frattali

Un’introduzione ai multifrattali piu impegnata, rispetto a quella intuitiva di considerarli come insiemi dipendenti da un parametro cosicche una misura dell’insieme puo avere dimensione D = D(h) funzione del parametro h (per esempio l’altitudine), richiede di procedere secondo una metodica piu rigorosa, e nello stesso tempo una breve introduzione illustrativa.

I frattali geometrici

Una definizione matematica chiara ed esaustiva di frattale che sia universalmente accettata non esiste ancora. Lo stesso Mandelbrot, da tutti considerato il padre dei frattali, nel corso degli anni ha proposto almeno tre definizioni: una forma o una figura frammentata, spezzata, fortemente discontinua (1978); un insieme per il quale la dimensione secondo Hausdorff e Besicovitch eccede rigorosamente la dimensione topologica (1982); una forma fatta di parti che sono in qualche modo simili al tutto (1986). La prima definizione e sicuramente valida intuitivamente ma troppo ingenua, qualitativa e non matematica per un personaggio come Mandelbrot; la seconda e troppo limitata e restrittiva non comprendendo alcuni dei frattali usati in fisica, mentre la terza e decisamente astratta e oscura. Definire un frattale non e semplice e nemmeno facile.