The SKALTA Experiment

Marek Bombara

Many ALICE collaborators are involved in teaching activities at universities. Very often they are the first people who introduce students into elementary particle physics and motivate them to choose this subject for PhD study.

Students interested in physics at high schools, or in their first years of university, are usually not very technically skilled for work in experimental particle physics. On the other hand, this disadvantage is counterbalanced by their enthusiasm. In my experience, high school students wish to discover the Higgs boson or study dark matter ( - and nothing less!). This interest is one we should underpin.

There are many possibilities as how to introduce to students experimental particle physics, even at a high school level, without requiring technical skills. One option could be the masterclasses where students analyse real events from ALICE (or from other LHC experiments) at a very popular level.

A second option could be a simple experiment with cosmic rays, like for example the SKALTA experiment at P.J. ?af?rik University in Ko?ice, Slovakia.

The SKALTA experiment (SlovaKiAn Large-area Time coincidence Array) measures secondary cosmic rays originating from a primary particle with energy more than 1014 eV. The experimental setup has similar architecture as the successful projects ALTA and CZELTA.

The working station is composed of three scintillation detectors, each with the dimensions 60x60 cm, connected in coincidence. The detectors are arranged into a triangle with a side length of 10 metres; the area of the triangle defining a minimal size of the shower and therefore a minimal energy of original primary particle (> 1014 eV).

Using the time difference among the signals from the detectors the point in the sky can be localized - up to a certain resolution - from where the original primary particle came from. By the measuring of the exact time by GPS the data from other workstations (i.e. CZELTA) can be compared and long distance correlations can be studied.

The detectors of the SKALTA experiment are installed on the roof of the Institute of Physical Sciences P. J. ?af?rik University in Ko?ice. The experiment started to collect data at the end of June 2010.

The detectors on the roof of P. J. ?af?rik University in Ko?ice.

The data format consists of a simple text file with numbers. At university level for the data analysis the ROOT framework can be introduced – students will have smoother transition later to the real analysis with AliRoot. An example of a student's work with SKALTA using ROOT is shown below.

Upper part: numbers of events measured by SKALTA per day, lower part: average daily atmospheric pressure at Ko?ice airport in hPa. Even though the distance between the stations is about 7 km nice expected anti-correlation can be seen.

The ALTA and CZELTA projects have also an important educational impact. Most of the workstations are installed on the roofs of high schools – offering the students an opportunity to participate in real scientific measurements.

One of the future goals of the SKALTA project is the installation of workstations on the roofs of selected Slovakian high schools, in order to make the education process more attractive, and to stimulate an interest in physics among students.

Students at the beginning of their university study, or at high school, may not discover the Higgs boson or study dark matter, but they can have a lot of fun in masterclasses or SKALTA-like experiments; with the data analysis potentially raising questions like: why is there no more antimatter? What was matter like within the first microsecond of the Universe's life? Simply, all the questions the LHC was built for.

Alice Matters