Brazilian physicists should increase participation in CERN

The assessment was made by participants in the High Energy Physics experiments at ALICE and CMS.

By Elton Alisson

Agência FAPESP – Brazilian researchers have contributed significantly to the scientific impact of the international collaborative experiments in High Energy Physics underway at the European Organization for Nuclear Research’s (CERN) Large Hadron Collider (LHC) in Switzerland. Nevertheless, the country’s scientists need to broaden activities at the site to benefit from both the scientific and technological opportunities afforded by participation in the projects.

This assessment was made by representatives of the A Large Ion Collider Experiment (ALICE) and Compact Muon Solenoid (CMS) collaborations during two workshops held by FAPESP on August 21 and 28 at the Foundation’s headquarters in São Paulo.

The objective of the meetings was to discuss the contribution and ways of increasing the participation of researchers from São Paulo State in ALICE and CMS, which are two of the four largest collaborations in Experimental Nuclear Physics underway at the LHC, the other two being the Toroidal LHC Apparatus (Atlas) and the Large Hadron Collider Beauty (LHCb).

“We want to understand a little more about the science conducted by ALICE and CMS, the participation of São Paulo researchers in these collaborations, the role these researchers could play in the future and how their work will contribute to the scientific and technological development of the state. This will give us greater knowledge and will help us make decisions about funding, organizing and supporting for these projects,” said Carlos Henrique de Brito Cruz, scientific director at FAPESP, at the opening of the first workshop.

According to the ALICE and CMS spokespeople present at the event, Brazilian researchers have played an important role mainly in the physical analysis and data processing of experiments conducted through these collaborations. These researchers are promoting, however, a more active participation in other critical areas of the projects, such as the development of scientific instrumentation to conduct the experiments.

“The Brazilian presence in ALICE has grown rapidly and has made a great impact in physics thanks in large part to the experience of very talented young Brazilian scientists,” commented Paolo Giubellino, an Italian national and a spokesperson for the collaboration that began in 2009.

“Now, however, Brazilian researchers are increasing their impact on the development of scientific initiation based on accumulated experience and have expanded their interaction with engineering groups involved in the collaboration,” he affirmed.

Brazilian participation in ALICE

According to Giubellino, ALICE was projected to study collisions of heavy ions – like those of iron – that occur in the collider at temperatures 100,000 higher than those registered at the Sun’s center.

The researchers hope that during the collision the heavy ions will be dismantled into a particle mixture called a quark-gluon plasma, which is believed to have existed in the first 20 to 30 microseconds after the beginning of the Universe.

“Based on this detailed study of the particles produced in nuclear collisions, it will be possible to infer the properties and behavior of matter in extreme conditions in addition to the evolution of the universe during the first microseconds of its birth with the big bang,” explained Giubellino.

According to the researcher, the collaboration involves more than 1,000 physicists from 132 universities and research institutions from 35 countries. Among them are researchers from the São Paulo Physics Institute at Universidade de São Paulo (USP) and the Gleb Wataghin Physics Institute at Universidade Estadual de Campinas (Unicamp). These researchers’ participation has mostly been concentrated on obtaining data and physical analysis of the phenomena observed during the experiments.

“We have participated in all stages of the physical analysis of the experiments conducted by ALICE,” commented Jun Takahashi, professor at IFGW-Unicamp, during the workshop. “We need to make efforts to participate in projects to update the detector and to have greater computing power to consolidate our contributions to the experiment,” stated the researcher, who currently participates in the ALICE experiments through a FAPESP-funded project.

The goal of researchers from the two São Paulo universities is to participate in the development of scientific instruments that will be incorporated in the next few years into the detector utilized by ALICE, which, like the detectors used in other collaborations, will be perfected for the experiments planned through 2023.

Beginning in 2015, the intensity of the proton beams will increase from 8 teraelectronvolts (TeV) to 14 TeV in the LHC. Particle collisions are expected to increase under this higher energy.

Consequently, scientists must improve the systems for reading, tracking, identifying and acquiring the data of the detectors to retain the capacity to identify and analyze the particles generated in the collisions and increase the precision of the measurements.

USP and Unicamp researchers intend to develop some of the devices to be utilized in these systems. Among them is an integrated circuit (microchip) that can be used for signal detection through ALICE’s Time Projection Chamber (TPC) – one the detector’s main pieces of equipment, which examines and reconstitutes the trajectory of particles – and a muon tracker – a device that uses sensors to identify these negatively charged particles, which are 200 times heavier than the electrons that pass through the detector.

To this end, the scientists intend to use their experience in the development of a series of Low Energy Physics projects for the Pelletron ion accelerator at the USP Physics Institute for the Relativistic Heavy Ion Collider (RHIC) and the Alternating Gradient Synchrotron (AGS) – both located at the Brookhaven National Laboratory in the United States.

“We have broad experience in the development of scientific instrumentation for Nuclear Physics and particles through a series of projects supported by FAPESP,” commented Marcelo Gameiro Munhoz, professor at the USP’s Nuclear Physics Department.

“We believe that Brazilian participation in scientific instrumentation for collaboration at ALICE has major potential and represents an excellent opportunity for the technological development and transferal of knowledge for companies in São Paulo State that offer support and at the same time benefit from the projects,” he evaluated.

Participation in CMS

Brazilian participation in the ALICE experiment is restricted to São Paulo State, with the teams from Unicamp and USP’s Physics Institute. The CMS collaboration, on the other hand, includes researchers from other Brazilian states, such as Rio de Janeiro.

Also founded in 2009, CMS has the objective of detecting and measuring subparticles released during collisions. The collaboration was responsible for the discovery of the Higgs Boson in July 2012 alongside the ATLAS collaboration.

CMS brings together more than 3,000 scientists from 40 different nationalities and 180 universities and research institutions the world over. Among them are researchers from Universidade Estadual Paulista (Unesp), the Universidade Federal do Rio de Janeiro (URFJ) and the Brazilian Center for Physics Research (CBPF), also in Rio de Janeiro.

The group of researchers from Unesp is part of the São Paulo Research and Analysis Center (SPRACE), created in 2003 through FAPESP funding. Through SPRACE, Brazilian researchers operate a processing network and participate in analysis of the data produced by CMS.

The cluster of SPRACE computers is also part of the LHC’s Worldwide Computing Grid (WLCG), which connects 100,000 processors in 34 countries, including Brazil, that transfer high speed data.

“The group of Unesp researchers is well integrated and visibly contributes to the success of CMS through computing,” comments João Varela, a Portuguese national and spokesperson for the collaboration.

“The experiments planned in the next few years and the improvements to the detector to carry them out create prospects for developing the scientific instrumentation group, which will be crucial for the success of the collaboration,” he stressed.

Recently, SPRACE joined a work group launched two years ago by the French National Centre for Scientific Research (CNRS) and Fermilab (U.S.) in collaboration with computer simulation specialists at CERN.

The group of researchers at SPRACE contributed to feasibility and performance studies on the detector utilized by CMS and comparative tests based on different data processing platforms.

“SPRACE should contribute to the development of one of the most crucial and challenging pieces of the CMS experiment, the detector’s signal tracker, and could extend and take advantage of its participation in the collaboration to gain experience in computer development and software tool usage in partnership with companies,” said Aurore Savoy-Navarro, professor at Paris-Diderot University and participant in the project.

According to the ALICE and CMS representatives, the system for developing the scientific instrumentation for the detectors utilized at LHC is “glocal” (global+local). The components are designed and built locally at the institutions participating in the collaborations and are later taken to CERN, where after approval they are added to other solutions developed by other countries.