Analysis and characterization of neutron scattering of a Linear Accelerator (LINAC) on medical applications.

A. LIMA FLORES1 , R. PALOMINO-MERINO1 , E. ESPINOSA1 , V.M. CASTAÑO2 , L. GUZMÁN-GATICA3 AND G. ESPINOSA4

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

2 Centro de Física Aplicada y Tecnología Avanzada, Universidad Nacional Autónoma de México, Boulevard Juriquilla 3001, Santiago de Querétaro, Querétaro C.P.76230, México

3 Servicios de Salud del Estado de Puebla, Antiguo Camino a Guadalupe Hidalgo 11350, Puebla C.P. 72490, México

4 Instituto de Física, Universidad Nacional Autónoma de México, Circuito de la Investigación Científica, Ciudad Universitaria, México D.F. C.P.04510, México

*Email: jaflores8630@gmail.com

Abstract 

In several theoretical and experimental studies, the topic of the undesirable generation of photoneutrons in rooms where a linear accelerator (LINAC) operates has been discussed. When energies above 10 MeV are used to produce X-rays and give radiotherapy treatment to patients resulting in additional radiation to patients. Accordingly, an analysis and characterization of the neutron scattering distribution on different zones in a treatment room contributes to evaluate the radiological health risk to patients, technical and other workers involved in treatment. For the evaluation, a device developed at the PAD-IFUNAM formed by a CR-39 detector enclosed by two 3mm thick acrylic plates was employed. To avoid environmental contamination, the CR-39 and the acrylics plates are enclosed in a round plastic box. Sixteen of these devices were settled in different places inside the treatment room, where a linear accelerator is used. The results show a significant concentration of neutron scattering in areas near the head of irradiation. The recommendation will be to evaluate the neutron scattering concentration in all rooms that’s operates a LINAC in order to verify the radiological health risk and to mitigate the neutron scattering when concentration levels are to high like those in our case, in order to avoid unnecessary exposition to patients and personnel in general. 

DOI: https://doi.org/10.15415/jnp.2017.51007

LINK: http://dspace.chitkara.edu.in/jspui/bitstream/1/867/1/51007_JNP_Lima-Flores%20Buap.pdf

Study of H2/N2Mixture Plasma Treatment on the AISI 1045

E. PARDO L.1*, J.G. GONZÁLEZ- RODRÍGUEZ1 , B CAMPILLO2 , F. CASTILLO2 , O. FLORES2 AND H. MARTINEZ2

1 Center of Research in Engineering and Applied Science, FCQeI UAEM., Av. Univ. 1001 Col., Chamilpa 62209, Cuernavaca Mor., Mexico

2 Institute of Physical Sciences, Autonomous National University of Mexico, P.O. Box 48-3, Av. Universidad s/n, Col. Chamilpa 62210, Cuernavaca Mor., Mexico

*Email: esteban.pardo@uaem.mx

Abstract:
 In the present work, we analyzed the effect of the plasma treatment of 80% H2 /20% N2 mixture plasma over the AISI 1045 steel. To produce the plasma, an AC discharge of 0.1 A at 350 V was produced at a total pressure of 3.0 Torr. The mixture plasma was analyzed using optical emission spectroscopy (OES), in the wavelength range of 200 to 1100 nm. The principal species observed in the plasma were NH, N2 , N2 +, H2 , and Hα. The electron temperature and ion density have been measured using a double Langmuir probe. The samples of steel were treated by plasma at different discharge times, between 3 and 12 h, at the same pressure and AC parameters (0.1 A and 350 V). The treated samples were characterized using X-ray analysis, finding the phases gamma and epsilon of iron nitride. The thickness of the nitrided layers was measured using a scanning electron microscope (SEM). From the images obtained, it is possible to appreciate the interphase between the nitrided layer and the steel matrix. The relationship between the morphology of the surface of nitrided steel and the wetting was analyzed by measuring the contact angle between the surface and a drop of 5 µL of distilled water. The contact angle of the drop increased with the increase of plasma treatment time. The control sample without treatment presented a smaller angle, and after the treatment the surfaces of the steel became hydrophobic. This may be related to the morphology change of the steel surface produced by plasma treatment.

DOI: https://doi.org/10.15415/jnp.2017.51006

LINK: http://dspace.chitkara.edu.in/jspui/bitstream/1/866/1/51006_JNP_Pardo%20-%20Fermin.pdf

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