by Mihai Petrovici. Published: 31 August 2016

Ultimate questions have been addressed by human beings since ancient times. As it is well known by now, the study of relativistic and ultra-relativistic hadrons and heavy-ion collisions has a strong impact on astrophysics, as this is the only way to create in laboratory conditions phenomena supposed to have occured in the very first moments of the Universe expansion (Big Bang) or in the core of neutron stars. Therefore these phenomena have a high potentiality to contribute to the answer of some of the ultimate questions. The high complexity of the accelerators, experimental devices and computing infrastructures, specific to this field of research, significantly enhanced the world-wide scientific collaborations. Although the big scientific centres are created around large-scale experimental facilities, bringing together international research groups of experimentalists and theorists, the construction and operation of such facilities are strongly based on the contributions coming from participating national laboratories and universities from different countries. This is where part of the complex detection and identification devices, associated electronics, software packages and theoretical models are designed, developed and constructed. Thus, the small centres remain a permanent resource of young talents, specialists and leaders in the field, if the local infrastructures are maintained at a level of international competitiveness and excellence.

Our group started its activities in the field of heavy-ion collisions 40 years ago. From studies of molecular type resonances we went to dissipative heavy-ion collisions bellow and around Fermi energies, and to relativistic heavy-ion collisions at SIS18-GSI within FOPI Collaboration. Our experience and achievements were strong arguments to join the ALICE Collaboration in 1999. We got involved in the research and development activities for the ALICE Transition Radiation Detector (TRD). The first prototype was tested at GSI and we had an essential contribution in designing the analog chip for the TRD frontend electronics. In the same period we started a local investment in setting up the appropriate infrastructure for a modern department. A general view of the department and some of its main facilities can be seen bellow. 

The Hadron Physics Department (HPD) of the National Institute for Physics and Nuclear Engineering (IFIN-HH) in Bucharest

The Hadron Physics Department - Detector construction, tests and chips bonding laboratories

Based on this infrastructure and local expertise, 24% of the ALICE-TRD chambers were assembled and tested in our Hadron Physics Department (HPD). Finalized in October 2008, this is the most important contribution which Romania has ever made within a large international collaboration.

The ALICE-TRD barrel equipped with TRD chambers produced in HPD

Members of the HPD actively participated in the installation of TRD supermodules inside ALICE and since the autumn of 2009 they have been helping in running the experiment, calibration and tracking for the TRD subdetector and data analysis.

The very high computing requirements for the simulation, calibration and analyses of the experimental information triggered the GRID activities initiated in our group in the early 2000. By November 2002, with the Computing Cluster of NIHAM, the first international GRID application in Romania was implemented within the ALICE GRID. Presently the NIHAM GRID site, with more than 2000 cores and 1.8 PB storage capacity, is one of the most efficient ALICE GRID Tier2 sites.

Top: Yellow-orange colour - NIHAM data centre, component of ALICE GRID. Bottom: jobs done in the last nine years by the Tier2 centres of ALICE GRID

Our group is involved in the analysis of transverse momentum (pT) distributions of charged particles and identified charged hadrons as a function of charged particle multiplicity and event shape aiming to evidence the production of deconfined matter and collective type phenomena in proton-proton collisions at LHC energies.

It is worth mentioning that within the ALICE upgrade programme, we are involved in the assembling and testing of 50% of the Outer ReadOut Chambers (OROC) of the ALICE-TPC, based on GEM technology.

A few international ALICE-related events were organized in Romania, as shown in the posters below:

Another segment of our activities is the research and development activity for a new generation of detectors and frontend electronics required for high intensity/luminosity future experiments. In this contest we performed a significant number of in-beam tests at the Proton Synchrotron (PS) and the Super Proton Synchrotron (SPS) at CERN, essential in studying the performance of high counting rate TRDs and Resistive Plate Chamber (RPC) prototypes developed by us in close-to-real conditions. The arrangement used to test our prototypes in the last year in-beam tests at SPS can be seen in the photo bellow – right side arm.

The new architectures of the TRD and RPC prototypes developed by us give access, besides the Particle Identification (PID) and very good time resolution, respectively, also to 2D position information with very good position resolution. This is highly required not only for the detectors in our experimental configurations but also by some applied research or technological transfer, as is demonstrated in the two representations below:  

The HPD acronym cutout in a copper tape illuminated by a 55Fe X-ray source seen by our TRD

A Monte Carlo generation of two gammas emitted by a 22Na positron source distributed as in the figure up-left and reconstructed by a RPC barrel with the time and position information corresponding to the RPC prototypes, bottom right.

The HPD is organizing Summer Student programmes, coordinates diploma, master and PhD theses and is hosting frequent visits of gymnasium and high-school pupils, students, foreign delegations, representatives of different embassies in Bucharest and from the Romanian Ministry of Education.

Now that Romania is a CERN member state, we really hope that the necessary conditions to enhance the synergy with real benefits on both sides will be created. The Romanian scientific community has the chance to become more coherent, competitive and visible within the ongoing and future collaborations at different experiments and other research activities carried on at CERN. This should be based on existing and future strong local infrastructures in Romania where most of the activities will take place and the new generation of scientists is formed. The access of all CERN facilities on equal footing, as a member state, will have a significant impact on the efficiency and motivation of many researchers or young talented students who are going to join this field of research in Romania. Last but not least, a smooth, long-range proper financing of the Romanian activities related to CERN, foreseen to happen being a member state, will have a strong impact on the expected results. Not speaking of other segments as technological and industrial sectors which, with a proper knowledge, dissemination and lobbying could have a real benefit.  

Professor Mihai Petrovici - head of the Hadron Physics Department