Department of Physics

Servicing of T0 frontend electronics inside of the ALICE detector

Servicing of T0 frontend electronics inside of the ALICE detector.

Instruments and Methods in Nuclear, Particle, and Astroparticle Physics

Conceptual drawing of Fast Interaction Trigger for ALICE upgrade.

The scope of activities of the group spans from cosmic ray experiment EMMA to T0 and FIT fast timing detectors for ALICE experiment at CERN, and Nuclear Reaction studies at the K130 cyclotron at JYFL. R&D on neutrino detectors is presented in the Neutrino Physics section.

Contact person: Wladyslaw Trzaska

  • Group members »
    • Wladyslaw Henryk Trzaska, senior scientist
    • Kai Loo, doctoral student
    • Maciej Slupecki, doctoral student
    • Johannes Hissa, doctoral student (Oulu University)
    • Yerzhan Mukhamejanov, doctoral student (Almaty University, Kazakhstan)
    • Antto Virkajärvi, student (Lappeenranta Technical University)
    • Jukka Sorjonen, MSc student
    • Roope Sarala, MSc student
    • Katja Karppinen, MSc student (Oulu University), 01.09.-31.12.2015
    • Patryk Edyko, summer student, 01.06.-31.08.2015
    • Konrad Cierluk, summer student, 01.06.-31.08.2015
    • Zofia Frątczak, summer student, 01.06.-31.08.2015
    • Przemysław Sędzicki, summer student, 01.06.-31.08.2015
    • Joni Ollikainen, summer student, 01.06.-31.08.2015
    • Jordan Koulikovski, summer student, 01.06.-30.09.2015
    • Grigori Tiurin, visiting researcher (Radium Institute, Russia)
  • Recent research
    • EMMA experiment »

      EMMA experiment, together with other scientific activities at the Center of Underground Physics in Pyhäsalmi, were evaluated in May 2015 by the Scientific Advisory Board (SAB) consisting of Anatoly Erlykin, Andreas Haungs (chair), and Jacek Szabelski. The SAB judged our team to be very active and highly motivated, with young researchers and students working seamlessly together. SAB was impressed by the quality and scientific content of the delivered presentations and discussions. Good progress was maintained despite absence of any direct funding for EMMA in 2015. To continue data taking and maintenance of the setup, our group accepted additional activities funded through a European Horizon 2020 application. They include involvement in an open-call for CALLIO-LAB, design and construction of a new laboratory space at 1430 m level and measurements of C14 contamination of liquid scintillators. In September the progress of our work was presented during the TAUP 2015 conference in Torino, Italy.

      EMMA team at Pyhäjärvi
      The Finnish team of the EMMA Collaboration together with 2015 summer students. Photo taken in Pyhäjärvi.

    • ALICE T0 and FIT detectors »

      In October 2015 the second phase of in-beam tests of the prototypes of the Fast Interaction Trigger (FIT) for the upgrade of ALICE experiment were conducted. The first test beam period was in June. Throughout the year FIT has reached several key R&D milestones achieving new time resolution records obtained with the modified prototypes. Our T0+ module consisting of Cherenkov radiator coupled to a MCP-PMT sensor clocked 22/18 ps with a broad/narrow beam and the V0+ scintillator module has, for the first time, reached 200 ps resolution. By modifications to the PMT-MCP light sensor we have significantly reduced the electronic crosstalk and increased the output amplitude without changing of the amplification. In 2015 the number of institutes participating in FIT has increased from 9 to 14.

      2015 has marked the end of the Long Shutdown 1 and the start of the LHC Run 2. The upgrade has increased the collision energy to Ös = 13 TeV for pp, and to ÖsNN = 5.02 TeV for the PbPb collisions. Throughout the 2015 running period T0 has performed flawlessly. 0TVX – the main trigger signal generated by T0 remained very clean, free from after-pulses, and not sensitive to the events resulting from the beam-gas collisions. The time resolution throughout the pp run was ~40 ps and in PbPb run, better than 25 ps! Despite the increase in luminosity, by so far, no signs of PMT ageing were detected. 0TVX served as the main luminometer for pp data taking. We have also prepared 0TSC – a new semi-central trigger requested by the trigger coordination. It provides a very clean signal, free from after-pulses and with reduced sensitivity to the electromagnetic component making it suitable for PbPb luminosity measurement.

      FIT team
      Fast Interaction Trigger (FIT) team photographed in October 2015.

    • Nuclear reactions »

      In 2015 the nuclear reactions team has continued the study of inelastic scattering and multi-nucleon transfer reactions measuring angular distributions of the differential cross sections for the 9Be (α, α') 9Be*, 9Be (α, 3He) 10Be, 9Be (α, t) 10B, 9Be (3He, 6Li) 6Li, and 9Be (3He, 7Be) 5He reactions. The information on the cluster structure of the reaction products was obtained and analyzed in the framework of the optical model, coupled channels, and distorted-wave Born approximation. An attempt was made to estimate the relative strengths of different configurations in 9Be. We have confirmed our previous result that the first excited state of 9Be (½+, 1.68 MeV), located only 20 keV above the decay threshold and playing an important role in nucleosynthesis, has a neutron halo structure. The cluster (α + 5He) configuration is more compact and the (3He + 6He) one is significantly suppressed.

      Nuclear reactions team
      Nuclear reactions team.