Se presenta los resultados del análisis estadístico de los promedios ponderados y años de permanencia en la Universida de los graduados en Física de la Facultad de Ciencias Físicas de San Marcos, durante el periodo 1985-1997. Sobre una muestra de 175 expedientes de graduados aprobados hasta octubre de 1998, se obtiene un promedio general de 12.66/20, con una desviación estándar de 0.58/20, en aprovehamiento y 7,74 años de permanencia promedio, con una desviación estándar de 2,67 años. Además, la tendencia de la correlación entre el aprovechamiento y la permanencia ha pasado de ser ligeramente positiva durante los primeros años a ligeramente negativa hacia el final de este periodo, con un valor de -0,21. Se hace una comparación del aprovechamiento de los graduados con su rendimiento en estudios de postgrado y con la tabla de conversión de la escala vegisimal a la escala li...

The energy dependent transport equation for X- and gamma radiation in a uniform medium is formulated. This medium contains trace amounts of an isotopic species capable of absorbing and emitting gamma radiation resonantly thanks to the Mössbauer effect. This equation is solved exactly for the case of an infinite medium and approximately for the case of a flat foil. These results are applied to the case of a radiactive Co-57 Mössbauer source in a metallic matrix to determine the spectral characteristics of self-absorption in the source matrix.

A theoretical model is presented to calculate the energy and relative intensity of escape peaks corresponding to the characteristic X-rays present in an energy dispersive X-ray fluorescence (EDXRF) spectrum. The escape peaks of elements present in high concentration in a sample interfere with the identification of characteristic X-rays of elements present in low concentration. The results of this analysis have been used to simulate with good results the presence of the escape peaks in a sample of wood ashes with high concentration of K and Ca.

Spectral analysis has been applied to time series of monthly mean values of D, H and Z components of the geomagnetic field recorded at the Huancayo Observatory (HMO). The maximum entropy spectral analysis technique, according to the algorithm by J.P. Burg, was used to calculate the coefficients for the errorprediction filter, and Akaike's criteria was used to obtain the length of the error prediction filter. The technique of fast Fourier transform as also applied to the same data with the porpose of comparison with the results obtained with the maximum entropy technique. Polynomials of second and third degrees were fitted to the D and H time series respectively by the least squares method, and a Fourier series with 30 harmonics was fitted to the Z time series. After removal of the tendency, which explains much of the secular variation of internal origin, the residual variations exhibit f...

We report the results of the study of a meteorite that impacted an inhabited zone in the neighborhood of the town of Carancas, Puno Region, about 1,300 km south of Lima. The analysis carried out by X ray diffractometry, transmission Mössbauer spectroscopy (at room temperature and at 4,2 K), and by energy dispersive X ray fluorescence reveal the presence in the meteorite simple of magnetic sites assigned to the Fe-Ni and troilite (Fe,S) phases, and of 3 paramagnetic doublets, two of them assigned to Fe2+, one associated to olivine and the other to pyroxene, and the third one due to a site occupied by Fe3+, which can be associated to oxides in a superparamagnetic state and/or by an Fe hydroxide. The soil samples from the crater reveal a composition that consists mainly of quartz, albite and impactites such as coesite and stishovite (SiO2). The occurrence of these phases with a high conten...

The existence of electric currents aligned with the magnetic field at low latitudes has been inferred using the methods of Gettemy [1] and Fukushima [2] applied to the magnetic data recorded in Peru during the International Geophysical Year (IGY) and the International Equatorial Electrojet Year (IEEY). The representation of the solar quiet daily magnetic variation, Sq, using magnetic contour maps of the D, H, and Z components of the magnetic field recorded at the Huancayo Magnetic Observatory (OMH) for the two time periods(1957 - 1958 and 1990 - 1991) was designed to visualize the seasonal changes in the daily variation. The maps obtained in this work are similar to the ones obtained by Gettemy [1] for the Magnetic Observatory at Koror (OMK) at the Palao Islands (Pacific Ocean) during IGY. The magnetic contour maps for the components of the magnetic field recorded at the Observatory of A...

Los compuestos de hierro (Fe) son muy comunes en la naturaleza. En el caso de suelos, se presenta en forma de sesquióxidos de hierro, tales como óxidos, hidróxidos y oxihidróxidos, así como cationes de sustitución en arcillas. Estos minerales se presentan en estado cristalino y amorfo. Por ser isotópicamente selectiva, la espectroscopía Mössbauer (resonancia gamma nuclear) permite identificar los minerales que contienen Fe aún cuando éstos están presentes en muy bajas concentraciones y en estado amorfo. En este trabajo reportamos los resultados preliminares del estudio que se viene realizando de muestras de suelos colectadas de la zona de Chinchero, Cusco. Los datos experimentales se obtuvieron por espectroscopía Mössbauer y difracción de rayos x; estos datos se complementaron con datos reportados por otros investigadores. En la preparación de las muestras se utilizó pro...

Herein, it is introduced the analysis of a meteoritic specimen discovered in the Peruvian Amazonia. According to the analysis by dierent physical techniques carried onto a fragment of it, this meteorite belongs to the ordinary chondrites. Specifically, we have used transmission Mössbauer spectroscopy and energy dispersive X-ray fluorescence.The results with these techniques show that the samples have relatively large amounts of Si, Al and Fe. Likewise, since transmission Mössbauer spectroscopy is an isotopically more selective technique, we have observed the presence of magnetic sites assigned to the taenite (Fe,Ni) and troilite (Fe,S) phases. We also realized the presence of three paramagnetic doublets assigned to Fe2+: one associated with olivine (Fe,Mg)2SiO4;other, to pyroxene (Fe,Mg)SiO3; and third doublet, to one Fe3+ site.

In this paper we study the mineralogical characterization of the clay fraction of two samples of agricultural soils from Vertisols from the Valle de San Lorenzo, Piura Region, using analytical techniques such as energy dispersion X-ray fluorescence (XRF), X-ray difractometry (XRD) and transmission Mössbauer spectroscopy (TMS). Prior to their mineralogical characterization, the samples were subjected to physicochemical analysis such as measuring their pH, removal of organic matter and textural analysis. In this work we have used two samples, which have been referred to as M1 and M2 and drawn two different calicatas at a depth of 50 cm and 150 cm respectively. Mössbauer spectra were taken at room temperature. Analysis of both samples by XRF indicated that both samples have approximately the same concentration of Fe, which was approximately 3,5% and 3,9% for M1 and M2 respectively. It als...

We report our results on compositional characterization of a ceramic sample from the site of Huacramarca, located in the Ancash region (Peruvian North-Central Highlands). ese results are based don XRD, XRF AND Mössbauer Espectroscopy analyses. Previous identication of compositional variability (based on macroscopical observations) suggest a pattern between dierent kinds of tempers and clay sources. Such patterns are strongly correlated with the variability identied through the outlined techniques, which allowed to go further and consider that alternative pottery-making processes were responsible for the Huacramarca assemblage. is suggests the possibility of dierent groups of people co-habiting in the settlement during the early part of the Late Intermediate Period.

We report our results on compositional characterization of a ceramic sample from the site of Huacramarca, located in the Ancash region (Peruvian North-Central Highlands). ese results are based don XRD, XRF AND Mössbauer Espectroscopy analyses. Previous identication of compositional variability (based on macroscopical observations) suggest a pattern between dierent kinds of tempers and clay sources. Such patterns are strongly correlated with the variability identied through the outlined techniques, which allowed to go further and consider that alternative pottery-making processes were responsible for the Huacramarca assemblage. is suggests the possibility of dierent groups of people co-habiting in the settlement during the early part of the Late Intermediate Period.

This paper reports the preliminary results of the mineralogical characterization of soils from the Chancay River Valley, Lambayeque, by X ray diffractometry (XRD) and transmission Mössbauer spectroscopy (TMS). The studied soil sample, SI53, belongs to one of the two horizons of a selected soil profile from the area of Sialupe, located in the Chancay River Valley. The XRD allowed the identification of crystalline mineralogical phases in the such as found sample, at a depth of 30 cm, such as quartz, montmorillonite, clinochlore, amphibole and albite; these same minerals, except amphibole, appear also in its corresponding clay fraction. The TMS allowed the identification , in the such as found sample, of a sextet assigned to hematite and a central doublet that can be assigned to an iron oxide in the super paramagnetic state or to kaolinite; the other doublets are assigned to montmorillonit...