Study of secondary muons detected within the tunnels of the Cholula pyramid

E. MORENO-BARBOSA1*, J.E. ESPINOSA-ROSALES1 , J. COTZOMI-PALETA1 , B DE CELIS-ALONSO1 , M. CRUZ-SÁNCHEZ2 , E. MERLO-JUÁREZ2 , P. TREJOGARCÍA1 , A. LIMA-FLORES1 , R. PALOMINO-MERINO1

1 Facultad de Ciencias Físico Matemáticas, Benemérita Universidad Autónoma de Puebla, Avenida San Claudio y 18 Sur, Col. San Manuel, Ciudad Universitaria, Puebla, Puebla. C.P. 72570, México.

2 Instituto Nacional de Antropología e Historia , Delegación Puebla, Zona Arqueológica de Cholula, 8 norte núm. 2, colonia centro , San Andrés Cholula, Puebla, C.P. 72760, México

*Email: emoreno@fcfm.buap.mx

Abstract 

The pyramid of Cholula was built at the beginning of 100 B.C. and during of period of 500 years it was finished, had several new constructions, based on the previous constructions. The primarily material of construction is the adobe. Early in 1931 archaeological excavations began with the intention of exploring the interior of the pyramid, excavations were stopped in 1971, and to date no further excavations have been carried out. This work shows the first measurements of muons, particles that are very penetrating, these are generated by primary cosmic rays that was incoming in the atmosphere and these generates a rain of secondary particles, among them the muons. To measure this kind of particles was implemented a detector system, it is formed by a scintillator plastic coupled to a tube photomultiplier; the signals were acquired by mean of an oscilloscope. The detector was collocated near of the center of the pyramid; the location belongs to the maxima concentration in mass over the detector. Graphs of the charge distribution, maximum amplitude and characteristic rise times of the generated pulses in a plastic scintillator are shown, this is scintillator was synthesized in the materials laboratory of the FCFM-BUAP. In addition the optical characterization of the same was realized.

DOI: https://doi.org/10.15415/jnp.2017.51005

LINK:http://dspace.chitkara.edu.in/jspui/bitstream/1/865/1/51005_JNP_Moreno%20-%20Palomino.pdf

Multiphoton Ionization of Uracil at 355 nm

E. PRIETO1 , A. GUERRERO1 , D. MARTÍNEZ1 , I. ÁLVAREZ1 , AND C. CISNEROS1*

1 Instituto de Ciencias Físicas-UNAM, Av. Universidad 1001, Chamilpa, 62210 Cuernavaca, Mor.

*Email: carmen@fis.unam.mx

Abstract We present the experimental results from ionization and dissociation by multiphoton absorption (MPI) of uracil and a mixture of uracil with Ar using a Reflectron time of flight spectrometer along with radiation from 355 nm at pulsed Nd:YAG laser . We focus on the light ions production. The MPI mass spectra show that the presence and intensity of the resulting ions depend on the density power of the laser. The resulting ions in the mass spectra are identified and found similar behavior in the case of H+ and C+ as when multiple charged ions are used. Different results were found in contrast with those, recently reported, when electrons or photons of other wavelength were used. The number of 355nm absorbed photons was calculated accordingly to Keldysh theory and similar results were fond using pure uracil or uracil-Ar mixture. Our results are compared with those obtained in other laboratories under different experimental conditions, some of them show only partial agreement and differences are discussed. 

DOI: https://doi.org/10.15415/jnp.2017.51004

LINK: http://dspace.chitkara.edu.in/jspui/bitstream/1/864/1/51004_JNP_Prieto%20-%20Cisneros.pdf

X-Ray Fluorescence Analysis of Ground Coffee

MARÍA CRISTINA HERNÁNDEZ1 , DARÍO ROMERO1 , HUMBERTO TORRES1 , JAVIER MIRANDA2,3*, AND A. ENRIQUE HERNÁNDEZ-LÓPEZ2

1 Facultad de Ciencias, Universidad Nacional Autónoma de México, Circuito Exterior, 04510, Coyoacán, Cd. Mx., MEXICO

2 Instituto de Física, Universidad Nacional Autónoma de México, Apartado Postal 20- 364, 01000 Álvaro Obregón, Cd. Mx., MEXICO 3 Centro de Ciencias de la Atmósfera, Universidad Nacional Autónoma de México, Circuito Investigación Científica, 04510, Coyoacán, Cd. Mx., MEXICO

*Email: miranda@fisica.unam.mx

Abstract :

Coffee is becoming one of the most popular beverages in Mexico. In the present work, X-ray Fluorescence (XRF) was used to determine the contents of several elements (with atomic numbers between 11 and 38) in 11 samples of commercial ground coffee, comparing with another one of soluble coffee and two of used ground coffee. Samples were dried at room temperature and pelletized. XRF analyses were carried out using a spectrometer based on an Rh X-ray tube, registering the characteristic x-rays with a Silicon Drift Detector. The system detection calibration and accuracy check was performed through the analysis of NIST certified reference materials 1547 (peach leaves), 1570a (spinach leaves), 1573a (tomato leaves), and 1571 (orchid leaves). As a general rule, the elemental concentrations measured are similar in all samples of coffee, in values not exceeding toxic levels. However, the differences among the elemental concentrations are shown.

DOI: https://doi.org/10.15415/jnp.2017.51003

LINK: http://dspace.chitkara.edu.in/jspui/bitstream/1/863/1/51003_JNP_Miranda.pdf

Radiation Induced Oxidation Reactions of Ferrous Ions: An Agent-based Model

A.L. RIVERA1,2,*, A.S. RAMOS-BERNAL1 , A. NEGRÓN-MENDOZA

1 Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México. Circuito Exterior S/N, Ciudad Universitaria, Coyoacán, 04510 Ciudad de México, México.

2 Centro de Ciencias de la Complejidad, Universidad Nacional Autónoma de México.

*E-mail: ana.rivera@nucleares.unam.mx

Abstract:
Chemical Fricke dosimeter in the laboratory can be submitted to gamma radiation at low temperatures to study the evolution of oxidation reactions induced by radiation, a key process to understand the formation of complex molecules. Products generated by the interaction of the different elements under radiation can be determined through a mathematical model that considers chemical reactions as coupled nonlinear ordinary differential equations involving the mass balance of all the species in the reaction. In this paper is implemented an alternative way of solving this system of equations, species’ concentrations are calculated through an agent-based model implemented in Python. The model is a modified version of the prey-predator model where each chemical specie involved is considered as an agent that can interact with other specie with known reaction rates leading to production (source terms) and to destruction (sink terms). Here, the radiation is a factor that affects product formation while the bath temperature modifies the reaction speed. This model can reproduce experimental concentrations of products and the consumption of ferrous ions from a laboratory reaction of irradiation of iron salt solutions at 3 different temperatures (dry ice, liquid nitrogen, and room temperature).

DOI: https://doi.org/10.15415/jnp.2017.51002

LINK: http://dspace.chitkara.edu.in/jspui/bitstream/1/862/1/51002_JNP_%20RIVERA%20-%20NEGRON.pdf

Atomic Multiplet and Charge Transfer Effects in the Resonant Inelastic X-Ray Scattering (RIXS) Spectra at the Nickel L2,3 Edge of NiF2

J JIMÉNEZ-MIER,1,* P OLALDE-VELASCO,2 P DE LA MORA,3 W-L YANG,4 AND J DENLINGER4

1 Instituto de Ciencias Nucleares, UNAM, 04510 Ciudad de México, México
2 Instituto de Física, Benemérita Universidad Autónoma de Puebla, Puebla, A. Postal J-48 Puebla,         Puebla 72750, Mexico
3 Facultad de Ciencias, UNAM, 04510 Ciudad de México, México
4 The Advanced Light Source, Lawrence Berkeley Laboratory, Berkeley, CA 94720, USA

 *Email: jimenez@nucleares.unam.mx

Abstract Resonant inelastic x-ray scattering (RIXS) is used to study the electronic structure of NiF2 , which is the most ionic of the nickel compounds. RIXS can be viewed as a coherent two-steps process involving the absorption and the emission of x-rays. The soft x-ray absorption spectrum (XAS) at the metal L2,3 edge indicate the importance of atomic multiplet effects. RIXS spectra at L2,3 contain clearly defined emission peaks corresponding to d-excited states of Ni2+ at energies few eV below the elastic emission, which is strongly suppressed. These results are confirmed by atomic multiplet calculations using the Kramers-Heisenberg formula for RIXS processes. For larger energy losses, the emission spectra have a broad charge-transfer peak that results from the decay of hybridized Ni(3d)-F(2p) valence states. This is confirmed by comparison of the absorption and emission spectra recorded at the nickel L and fluorine K edges with F p and Ni d partial density of states using LDA + U calculations. Keywords: Core-level spectroscopies. RIXS, Nickel difluoride, Electronic structure

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http://dspace.chitkara.edu.in/jspui/bitstream/1/861/1/51001_JNP_JIMENEZ.pdf