by Panos Charitos. Published: 18 December 2012

A.M How did you choose the field of high energy physics? 

Perhaps the choice of our profession is done when we are too young. Over the years, we assimilate that such election will mark the rest of our life and it's influenced by many factors: family, ideals (if not dead), economic status and even the place where you were born.

In my personal case, I wanted to study a profession or occupation for which I feel the pleasure of getting up every day of my entire life and also that allowed me to be independent, to contribute to the growth of my community and over a few years to start a family. I had several careers in my mind: computer science, mathematics (influenced by my father who is a mathematician), political science (influenced by my mother who is a lawyer), dramatic arts and physics. As I didn´t want to work in an area where the arrogance, money and corruption exists, the choice was between physics and mathematics (paradoxically in a world where the science is assumed as devoid of corruption and aim away from vices systems created by ourselves).

In the end I chose physics because it is an area where mathematics loses some of its abstraction to aid understanding of nature. I got my bachelor's degree in Physics at the Faculty of Physics and Mathematics of Autonomous University of Puebla (FCFM-BUAP, MX). Over five years (2001-2006) I was struck by Statistical Physics and Optics (geometrical and optical physics) . In fact, my bachelor's thesis was focused on optical surface reconstruction algorithms based on fuzzy mathematics applied in interferometry.



Mario Rodriguez Cahuantzi did his PhD with ALICE and is currently working with ACORDE Puebla Group.

How long you have been working with ALICE and what has been the subject of your research?

I joined the ALICE Collaboration at the end of the first year of my master studies when I met Arturo Fernández (ALICE-Puebla team leader) who kindly invited me to work with his group in ACORDE. I visited CERN for the first time in 2007 for one month to help with the commissioning and offline tasks for the cosmic ray trigger with the support of HELEN program. Then I had another two stays at CERN with this program (5 and 6 months). At the same time I started working with Eleazar Cuautle (ICN-UNAM).

In 2008, I started my PhD studies at FCFM-BUAP under the supervision of Arturo and Eleazar in close collaboration with Bruno Alessandro (INFN-Torino). The main topic of my PhD thesis was focused in searching high atmospheric muon multiplicity events that reach ALICE and its interpretation with Monte Carlo studies commonly used in cosmic ray physics (such events were reported previously by LEP experiments). Furthermore, during the last year of my PhD. studies; I stayed at CERN with the support of ePlanet program working with Daniel Tapia (one of PAG-UPC conveners) in the analysis of J/psi photoproduction in the forward region of ALICE. Additionally, I was in charge of the DQM of ACORDE. I defended my PhD thesis in August 2012.



ACORDE (The Alice COsmic Ray DEtector) is the main cosmic trigger system in ALICE; it is located on the top of the ALICE magnet.

What is ACORDE and why is a cosmic rays detector needed in a heavy-ion experiment?

ACORDE (The Alice COsmic Ray DEtector) is the main cosmic trigger system in ALICE. It is located on the top of the ALICE magnet. Before the start of LHC operations, ACORDE was used for calibration and alignment of the central detectors. Additionally, the ACORDE trigger has been configured to detect high atmospheric muon multiplicity events. In order to increase the live time of data taking for the cosmic trigger, ACORDE has been included in the p-p data taking runs.

Which were the main challenges in building ACORDE?

The essence of human beings is inherently complicated. Thus, teamwork is a challenging itself. Also, designing and building a detector in Mexico before installing it in the other side of the planet is a huge challenge. This process involves life style, language and work methodology adaptation (which is already well defined inside the research groups at CERN). The experimental particle physics group of Puebla already had the experience of participating in big experiments like Pierre Auger, LAGO and in recent years HAWC and Tatiana (satellite program in collaboration with Russia). Given the importance of LHC, the next step was the addition of some people from Puebla to CERN experiments (besides ALICE, Puebla is an official member of CMS experiment).

What have we learnt from ACORDE?

Conducting cosmic ray physics studies in a heavy ion experiment seem to be difficult and perhaps a little improvised. The pioneers in these studies were LEP experiments. With the inclusion of ACORDE as a cosmic trigger during p-p data taking runs, we proved that it is possible to study different physical phenomena with the same detector at the same time. This is something new that can be exploited by ALICE to make an important contribution to the cosmic ray physics. People of experiments such as KASKADE-Grande, Auger and Emma have been interested in the results obtained by ALICE so far.

What are your future plans regarding your personal career and personal aims?

Something I had not mentioned here before, is that during the second year of my PhD; me, Diana Maya (my wife) along with Diana Yaretzi (my 2 years old daughter) decided to form a special collaboration (we got married). So, now all the personal goals have become in common targets. In the short term we are considering the inclusion of a new family member. For the time being, we continue working with the ACORDE Puebla group. In the mid term, we are looking for a position (in ALICE or another experiment) that will allow us to establish a fixed residence for some years!



Mario Rodriguez and his collaborators:Diana Maya (his wife) and their 2 years old daughter Diana Yaretzi.

And your future plans regarding your collaboration with ALICE especially given the recent endorsement of the ALICE Upgrade Plans?

There are plans to work for the ALICE upgrade (ADA, ACORDE). Also for the analysis of proton-lead data coming at the beginning of the next year and proton-proton analysis in order to understand deeply the hadronic interaction models commonly used in cosmic ray physics. Personally, I would like to continue in ALICE for some more years and then move to another experiment (not necessarily at CERN, diversity is good to keep a fresh mind). I want my period as an ALICE member to be as enriching as possible.