Wednesday, March 25, 2015

Cosmic Rays

Why do we study cosmic rays?

Earth based accelerators, cannot give us all the reasons behind particle interactions. I remember that my UCSB thesis advisor, Robert L. Sugar told me in 1973, to look into the expanding proton phenomenon.  Cosmic ray physics had shown us, that the probability for protons to collide INCREASES, as the energy increases beyond certain point. I was, and still am, very intrigued.

Taken from arXiv

Without cosmic ray observations we would've not known that. In fact the probability for two protons to collide DECREASED with energy, up to certain energies.

The results of my research are here.

The first job in my life, was  as a laboratory assistant, at the Mexican Nuclear Energy Commission in 1970. I was then a senior, at the department of Communications, and Electronics Engineering, at Escuela Superior de Ingeniería Mecánica y Eléctrica, of the Instituto Politécnico Nacional (IPN) in Mexico City. I worked at the Plasma Physics Laboratory. My boss, Mario Vázquez Reyna, under the direction of Manuel Sandoval Vallarta, a pioneer in Cosmic Ray Physics in Mexico, had built electronic detectors. I studied plasma magnetic confinement at the laboratory. During that year, I decided to study Physics instead of electronics. I did not want to build detectors for others, I wanted to propose the needed observations, to prove ideas in Physics.

The opportunity came along, in the field of cosmic rays, with the invitation to join the Pierre Auger Observatory in 1994. I was on a sabbatical leave from the Autonomous University of Puebla, at the Fermi National Laboratory in Batavia, Illinois, My professor Arnulfo Zepeda Domínguez, was invited, by the Nobel laureate James Cronin, from the University of Chicago, to join this international collaboration; and professor Zepeda invited me. The university in Puebla had very good conditions to join this effort. I was working at the Escuela de Ciencias Físco Matemáticas, which was started by professor Luis Rivera Terrazas, precisely to join  international efforts in modern physics. There were  Physics, Mathematics, Electronics, and Computer Science departments.

As soon as I went back to Puebla, I talked with my friend Alberto Cordero Dávila. With his experience at the Instituto Nacional de Astrofísica Óptica y Electrónica in the nearby town of Tonantzintla, he immediately proposed the kind of instrument to use for the light collecting part of the observatory, the Schmidt Camera, which was adopted by the collaboration.

There is a surface detector part of the Auger Observatory, working together with the optical one mentioned above. Here my friend, Humberto Salazar Ibargüen, took the initiave. Professor Salazar obtained his Ph.D. working at the General Relativity Group of professor Jerzy Plebanski, at the Centro de Investigación y de Estudios Avanzados of IPN. He addressed the many technical problems, to build water tank detectors, with Cherenkov phototubes.

Eventually this work led to its inclusion, in the list of top ten best science breakthroughs of 2007 in Science Magazine.

I am happy to report news: There is a  a bigger step forward for Mexican Cosmic Ray Physics, which owes a lot to my friend Humberto.

The HAWC experiment is actually in Puebla.

We can read from the link above.

The High Altitude Water Cherenkov Experiment or High Altitude Water Cherenkov Observatory (also known as HAWC) is a gamma-ray observatory located on the flanks of the Sierra Negra volcano in the Mexican state of Puebla at an altitude of 4100 meters, at 18°59′41″N 97°18′30.6″W. HAWC is the successor to the Milagro gamma-ray observatory in New Mexico, which was also a gamma-ray observatory based around the principle of detecting gamma-rays indirectly using the water Cherenkov method.

I am humbled by the work done by my friends in Mexico.

Arnulfo Zepeda told me that Manuel Sandoval Vallarta, conveyed to him, his wish, that Cosmic Ray Physics in Mexico must continue.

Professor Eduardo Piña Garza spent some time with us at Puebla. He had studied the motion of electrically charged particles in the Earth's magnetic field; continuing the work of Carlos Graef Fernández. I can attest to the high caliber of professor Piña, because I was fortunate to publish an article with him.

Mario Vázquez Reyna, and Manuel Sandoval Vallarta, would've been as happy as I am, for the Mexican contribution to Cosmic Ray Physics. 

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